Environmental health

The new guidelines should be useful to all medical practitioners and fair to patients Driving a motor vehicle is a complex task involving perception, good judgement, adequate response time and reasonable physical capability. A range of medical conditions, as well as certain treatments, can impair any of these factors. Such impairment may adversely affect driving ability, possibly resulting in a crash causing injury or death (Box). Case report An eight-year-old girl was walking with her family on a footpath. A car driven by a driver who had poorly controlled diabetes and was suffering a hypoglycaemic episode mounted the kerb, killed the girl, and injured members of her family. The coroner was critical of the driver who failed to take responsibility for his condition, failed to attend medical appointments and education as requested, ignored the obvious risk of his continuing to drive, and deliberately sought to retain his driver licence by “doctor shopping”. The various doctors involved in the driver’s treatment were also criticised for the lack of clarity and consistency of information given to the driver regarding driving restrictions and the lack of action in response to “red flags”. They were also criticised for not notifying the driver licensing authority of concerns about the person’s continued driving.1 Although South Australia differs from most states and territories in explicitly requiring a medical practitioner to notify the authorities of patients who have conditions likely to impair driving, the issue has ethical resonances for the profession nationwide: doctors have significant medicolegal responsibilities regarding their patients and safe driving, and should act accordingly; although doctors must respect patient confidentiality, nearly all states and territories provide indemnity for a doctor to notify the driver licensing authority if an unsafe patient cannot be persuaded to self-notify and continues to drive; and conditional licences may be recommended for patients if certain treatment, compliance, response and review criteria are met. This helps ensure the quality of life for the patient. Doctors should be aware of these options. The newly published Assessing fitness to drive 20032 gives guidance to healthcare practitioners faced with various clinical situations. It also provides specific guidance on conducting medical examinations required by the licensing authorities. The overall intent of these national guidelines is to help clinicians: identify and manage patients who may not be capable of adequately controlling a vehicle (and who are thus a risk to public safety); counsel patients regarding the impact of their condition on their driving ability; inform patients of their legal obligations to report long-term or permanent illnesses or injuries likely to affect their driving to the driver licensing authority; and if needed, because of inaction by the driver and immediate concerns about public safety, advise the driver licensing authority regarding the patient’s fitness to drive. The new publication replaces the existing booklets Medical examinations for commercial vehicle drivers (1997)3 and Assessing fitness to drive (2001) for private vehicle drivers,4 and combines both these booklets into one reference for ease of use. The medical criteria for commercial drivers are more stringent than those for private vehicle drivers, reflecting their extensive time on the roads and the likelihood of more serious consequences of loss of control of, say, a petrol tanker or bus compared with a domestic car. These different criteria are set out in colour-coded format throughout the new book. In addition to combining the standards for commercial and private vehicle drivers, the content has been extensively revised to reflect advances in diagnosis, treatment, and prognosis of various conditions affecting driving ability. For example, increasing recognition of the importance of fatigue and sleep disorders in accidents5 has led to inclusion of the Epworth Sleepiness Scale as a screening tool in the health questionnaire,6 and the more accurate and cross-culturally validated AUDIT questionnaire has replaced the CAGE questionnaire for alcohol dependency screening.7 Similarly, advances in treatment of diabetes, epilepsy, and psychiatric disorders have been incorporated. Much attention has been given to “conditional licences”, whereby a person who does not meet the medical criteria may be supported in retaining a driving licence that is conditional on supplementary criteria relating to compliance and response to treatment, possible driving restrictions, and a detailed plan for monitoring the patient’s condition. This should help in rehabilitation of patients with various conditions, and address concerns about disability discrimination and equal employment opportunity issues. Several legal and ethical issues are also identified in the guidelines. The book emphasises the legal responsibility of drivers to notify the driver licensing authority if they have any permanent or long-term condition likely to affect their driving ability. The relevant state legislation in this regard is included as an appendix. The legislation relating to reporting by healthcare practitioners is also summarised in the book. Most states (with the exception of South Australia and the Northern Territory, where legislation is under review) do not require mandatory reporting by healthcare professionals. However, there remains a duty of care in cases where the healthcare practitioner is aware of the patient’s continuing driving and there is a definite risk to public safety.8 Practitioners who are unsure about confidentiality and notification should consult their medical defence organisation or state driver licensing authority regarding their legal position. The introduction of privacy legislation in most states has also been a consideration, and has led to clarification of the information to be recorded and kept by the practitioner (and to be readily available to the patient/driver), as distinct from the medical information to be provided on a “need to know” basis to the licensing authority. The exception is information required to be provided to the authority under law. This has led to new forms and procedures to guide practitioners. Although overall there is a move to uniformity of licensing procedures in the different states and territories, there are still some important differences. Tables set out these differences for easy reference. In summary, Assessing fitness to drive 2003: outlines clear medical criteria for driver capability, based on available evidence and expert medical opinion; clearly differentiates national minimum standards for licensing drivers of commercial and private vehicles; outlines the legal obligations for medical practitioners and drivers; provides medical examination proformas to help guide the assessment process; provides a reporting template to guide reporting to the licensing authority if required; and provides links to supporting and substantiating information. The new guidelines have been developed through extensive consultation with the medical profession, the licensing authorities, the trucking industry and unions, and lay groups. The development of the book is one of a series of initiatives by the National Road Transport Commission to create uniformly efficient and safe transportation in Australia.9 In recognition of its importance, the book has been signed into force by the ministers of transport of all states and territories. The book has been assessed by general practitioners and found to offer clear clinical and procedural advice for various situations. It is intended the new guidelines will be useful to all practitioners, be fair to patients, and contribute to road safety. Copies of the new guidelines are being distributed to all GPs, and may also be obtained free of charge from state driver licensing authorities. The guidelines are also accessible online from the Austroads website (www.austroads.com.au), and an online tutorial package is being developed to support implementation.

Bruce Hocking FAFOM, FAFPHM, FRACGP · Fiona Landgren B Pharm, Grad Dip Hosp Pharm

Andrew B Black,* Sam F Berkovic† * Neurologist, The Queen Elizabeth Hospital, Woodville, SA; and Chair, Driving Committee, Epilepsy Society of Australia. † Neurologist, Austin and Repatriation Medical Centre, West Heidelberg, VIC; and President, Epilepsy Society of Australia. Correspondence: Dr A B Black, Ashford Specialist Centre, 57–59 Anzac Highway, Ashford, SA 5035. abblackATchariot.net.au To the Editor: Seizure disorders are often the most scrutinised medical conditions in relation to road accidents.1 Epileptologists internationally have reached some consensus on the role best played by treating doctors: ensuring patients receive proper medical care; advising on assessed risk and its minimisation; and reporting (if necessary, without patient consent) when a patient becomes a risk yet continues to drive.2 In a recent editorial on sleep disorders and driving,3 McEvoy also emphasises the essential role of first establishing the therapeutic relationship, and refers to the impending release by the National Road Transport Commission of new medical standards for all vehicle types.4 Australian neurologists and the Epilepsy Society of Australia find that the new guidelines are imprecise in defining the role played by doctors and Driver Licensing Authorities (DLAs), and are excessively detailed with cumbersome processes that are open to confusion. The instructions for using four separate forms (3.3) are complex and imprecise, giving no indication about discretion in their use or non-use. Moreover, it is not the role of doctors to define specific restrictions for holders of conditional licences (3.3.1), but that of the DLA. Demands on doctors for surveillance and enforcement are excessive, and by interfering with the maintenance of proper rapport may prove counter-productive. The roles for consultants are not clearly defined. A more desirable model is one in which the DLA takes responsibility for all legally enforceable decisions and does not expect treating doctors to decide on fitness-to-drive. A treating doctor may provide factual information, but is not expected to give an opinion on licensing questions. This model, used in the United Kingdom,5 is simple, well understood and respected. The DLA there obtains independent medical advice in deciding borderline cases, an optional mechanism given little attention in the Australian review. Doctors in the UK are well aware of their common law duty to report patients if their actions are endangering. We are drifting away from this simpler and ethically and medicolegally more satisfactory model at our peril. We should re-engage our DLA colleagues to establish a more effective relationship, in which they ensure their licence holders are well informed of their obligations, while we provide the expert care and management of our patients which will best encourage a safer driving environment.

Andrew B Black · Sam F Berkovic

Disease prevention, access to services, and continuity of care are the important areas Health inequities are systematic differences in health status between different groups in the population, and may or may not be changeable. Health inequity is taken here to mean inequalities that “are unnecessary, avoidable, unfair and unjust”.1 Inequities in health usually relate to socioeconomic position, ethnicity or sex. Examples associated with chronic disease in Australia include: Higher mortality rates from cardiovascular disease, diabetes, and renal disease among Aboriginal and Torres Strait Islander populations;2 Higher mortality rates from coronary heart disease, stroke, and chronic respiratory conditions among lower socioeconomic groups;3 and Higher mortality rates from vascular diseases, suicide and accidental death, and lower survival from cancer among people with mental illness.4 One estimate of the size of this effect is that, if disease and injury incidence and mortality in all areas were reduced to the level in the least disadvantaged quintile, the potential savings in lost years of “healthy” life would be 17% of the total disease burden.5 Only some inequalities in mortality are potentially avoidable through the activities of the health and related sectors; analysis of these can indicate opportunities to reduce health inequities. Interventions against potentially avoidable mortality can be divided into three levels: primary (preventing a condition from developing; eg, by treating hyperlipidaemia), secondary (preventing the worsening of a condition at an early stage; eg, screening for and treating early disease), and tertiary (curing disease or extending life through treatment).6 An analysis of trends in avoidable deaths in New South Wales from 1980 to 2000 showed: The burden of potentially avoidable mortality decreased overall and across all socioeconomic status (SES) groups during the 20 years; however, the rate of reduction was higher in the highest SES group than in both the lowest SES group and the rest (middle 60%) of the population. Ischaemic heart disease, lung cancer and colorectal cancer contributed most to this burden in 2000. About half the potentially avoidable deaths are preventable through primary prevention, a quarter through secondary prevention (mainly ischaemic heart disease, stroke, and colorectal cancer), and a quarter through tertiary prevention and rehabilitation (mainly ischaemic heart disease). The proportion of primary preventable causes rose slightly, indicating a relatively greater reduction in causes associated with secondary and tertiary interventions during the period.7 Information on inequities other than mortality is not extensive in Australia, owing to lack of suitable data collections. One study suggests timely and effective ambulatory care (encompassing preventive care and early disease management) may reduce the risk of hospitalisation by preventing an illness, controlling an acute episodic illness, or managing a chronic condition.8 Hospitalisation rates in NSW and Victoria for conditions potentially avoidable through ambulatory care were similar (6.2% and 7%, respectively).7,8 The five most common such conditions were angina; asthma; chronic obstructive pulmonary disease; convulsions and epilepsy; and ear, nose and throat infections. Targeting disease preventionPotential health system responses to health inequities include health promotion, higher treatment levels for targeted populations, more effective treatment (eg, given earlier, or with better compliance) and improved use of resources through better coordination and information sharing.9 The data above indicate that, although a multi-pronged approach will be necessary, the largest population benefit will be through making prevention programs more effective. Well-documented differences in chronic disease risk behaviours include higher prevalence of smoking, obesity, and high blood pressure in low SES groups.3 How prevention strategies can be more effective among low SES groups is the subject of much controversy and little systematic research. Many authors believe that traditional approaches to health promotion will not be effective because the capacity to make “healthy” choices is strongly linked to environmental and social factors that accompany poverty and disadvantage. Determinants of health can be considered at upstream (social, physical, economic and environmental), midstream (psychosocial and health behaviour), and downstream (individual) levels.10 Health promotion within clinical services has traditionally focused on the individual level, although public health preventive activities have generally had the most effect when implemented at upstream levels. Given the limitations of the existing evidence for reducing socioeconomic health inequities, interventions that have been effective with other health problems are a good starting point.11 Targeting access inequitiesAustralian data on potential differential access to services are limited and largely confined to geographic access for people in rural and remote areas. There is no whole-of-population dataset that systematically looks at the quality and effectiveness of care for chronic disease in groups experiencing health inequities. However, studies suggest there is much room for improvement. For example, in 98 000 general practitioner encounters, holders of healthcare cards (who are on aged, disability, unemployment or other low-income pensions) were more likely to have chronic diseases and fewer preventive measures (such as Pap smears).12 At the tertiary care level, patients of lower SES had less access to invasive procedural treatments following admission for coronary heart disease in Queensland.13 As our healthcare system is oriented to acute care, chronic care treatments that reduce disability (eg, joint replacement surgery) are likely to have lower priority and therefore be more difficult to access. Such inequities of access may be greater for dental care, physiotherapy, speech therapy, dietetics and podiatry, which are not subsidised outside public hospitals. Thus, in redistributing resources for health problems where inequities exist, it is important to ensure that the investment is made where the effect is likely to be greatest. Targeting continuity of careAchieving continuity of care across healthcare sectors is a major problem in the care of people with chronic disease, especially those disempowered by way of income, language, or culture. Delivery of care and support services by multiple professionals and agencies compounds the problem. Appropriate rationalisation of such arrangements and good coordination of care can lead to better outcomes. Any attribute of our healthcare system that impairs any health outcome will be compounded for people who are poor or otherwise disadvantaged. Indeed, it will be difficult to redress health inequities for people with chronic disease without addressing the broader problems in the system. However, without specific attention to health inequities in research, planning and policy (see Box), the current differences will not go away, and may even increase. Requirements for addressing health inequities in the care of people with chronic disease Better data on health inequities across the continuum of care, to produce key indicators for regular monitoring. The available data already indicate that a high priority should be given to prevention and management of cardiovascular disease. Appropriate use of data in decision making. The National Health and Medical Research Council (NHMRC) has recognised the potential for clinical practice guidelines to affect health inequities both positively and negatively, and has produced a guide on how to use socioeconomic evidence when developing guidelines.14 Greater investment in prevention, with particular attention to disadvantaged groups. Funding for programs needs to recognise the lack of primary healthcare infrastructure to deliver prevention in many disadvantaged communities and the need to make longer-term funding commitments (5–10 years) for such programs. Local or regional initiatives to ensure active coordination of all care. Funding mechanisms that provide better access to non-medical therapies such as podiatry and dietetics.

Andrew J Wilson PhD, FRACP · Alan D Lopez MSc, PhD · Brian F Oldenburg BA, PhD

It is time for debate to become policy Recognition is growing worldwide that chronic, non-communicable disorders (often, but not exclusively, associated with ageing) and hidden disability are acting in concert with burgeoning technologies to make healthcare more expensive. As communicable diseases are controlled, and social and economic conditions develop to support longer life expectancy, the challenge of preventing and managing chronic disease grows greater. A recent report of the Australian Institute of Health and Welfare confirms that Australia is facing an increasing economic and social burden because of chronic diseases and their associated risk factors.1 Twelve chronic diseases and conditions accounted for an estimated 42% of the total disability-adjusted life years (DALYs) lost in Australia in 1996, and all such diseases and conditions accounted for about 80% of DALYs.2 The report noted the difficulties of defining chronic disease, and concluded that “. . . though open-ended, it is usually defined by a minimum duration (for example diseases lasting 3 or 6 months, continuously or intermittently, may be termed chronic)”.2 Illustrating the semantic divide, a recent report of the United States Institute of Medicine focused on the inadequacy of care of chronic conditions, and defined a chronic condition as one which “. . . requires ongoing medical care, including monitoring, treatment, and coordination among multiple providers, limits what one can do; and is likely to last longer than 1 year.”3 In the mid-1990s, the National Health Target strategies were developed by the Australian government, following the Better Health Commission’s report in 1987. Since then, much more has been written on the need for more efficient and better-coordinated policies for preventing and managing chronic conditions in Australia. A range of viewpoints, disease targets and high-level overviews have emerged in proposals by the National Health Priority Action Council, the National Public Health Partnership, the Department of Health and Ageing Sharing Care Initiative in the 1999–2000 Budget, the Rural Chronic Disease Initiative, the Strategic Research Development Committee of the National Health and Medical Research Council, and advisers forging the next Australian Health Care Agreements.4 US leaders in the development and evaluation of integrated models of care for people with chronic illness, such as Kaiser Permanente, and Group Health Cooperative of Puget Sound, have shown that the burden of chronic disorders can be reduced by informed primary care practitioners and patients working together, supported by evidence from modern information technology.5 Yet in 2003, when other nations have moved beyond talk into detailed proposals for reforming the prevention and management of chronic conditions, Australian governments still debate.3 Gaps in our health policy research into preventing chronic illness and managing and financing chronic care are wide, confirming the lament of a recent editorial in this Journal.6 Three of these gaps deserve special mention. First, while some prevalence rates and use of hospital resources have been estimated, accurate data are lacking about how the total direct costs of managing chronic conditions vary with age, number of risk factors or number of comorbidities. Recent US research provides the first indications of the increases in direct costs as the number of risk factors increases. The increased costs are pronounced for prescribed drugs, and less so for hospital and medical services.7 Disability is a major driver of the direct and indirect costs in an ageing population.8,9 Five conditions (mood disorders, diabetes, heart disease, hypertension and asthma) accounted for 49% of direct healthcare costs in the United States in 1996, and for 42% of illness-related indirect costs.10 To obtain more accurate projections of future care costs, we need new coding systems that measure comorbidities, and linked data sets provided by all care providers and payers. Second, better data about the costs of the prevalent risk factors listed in the Australian Institute of Health and Welfare report1 are essential. The World Health Organization has laid out the empirical rationale for such a campaign against risk factors.11 With these cost data, the economic case for their prevention can be opened to public debate. Economic incentives to the community to reduce their risk and look after their health have not been conspicuous in Australia. Health economists have generally argued against investments in public education and information that might modify demand for healthcare in favour of government regulation of the supply side. They may wish to adapt their arguments in the light of evidence on the impact of demand-side strategies in US chronic disease management trials.12 Third, there is no clear evidence of the success of initial attempts to organise and pay more efficiently for the management of chronic conditions. The first trials of coordinated care in Australia were not designed, managed or funded adequately to demonstrate significant achievements in health and functional status, or cost reductions compared with usual care. The findings from the evaluations of these trials reflect these limitations13 and contrast with the results of the US Medicare Coordinated Care Demonstration14 and with US evaluations of integrated care models, such as the Program of All-Inclusive Care (PACE) for the frail elderly,15 a small subset of the chronically ill. In Australia, the second set of trials of coordinated care is under way. Unfortunately, private health insurers are not much involved. In fact, there is no incentive in the current Reinsurance Pool for private health insurers to provide coordinated care for their members with chronic disorders. This pool reimburses funds whose members receive high cost, lengthy hospital care, while extracting payments from funds with lower cost members. Some state governments, most notably the New South Wales government through the work of the NSW Health Council, have declared an interest in managing several chronic conditions, such as diabetes, chronic respiratory disorders and heart failure. Regrettably, current funding mechanisms and political timidity prevent anything as radical as cashing out all federal payments to allow the states to implement risk-rated capitation funding allocated to the continuum of care needed by chronically ill people. It is time to bring the private healthcare sector into the policy review process. The recent report of the US Institute of Medicine identified the need to make best use of all resources, public and private, in a mix of new types of care, using adequately funded demonstration projects that had the appropriate mix of information technology, evidence-based clinical practice guidelines, coordination of care by multidisciplinary teams, and linkage of universities into the learning process.3 The US government policy review strategy for coordinated care differs markedly from the Australian strategy in one other respect. In July 2000, the lead US government agency sought public comment on both the contents of its proposals and the design features of the proposed demonstrations of coordinated care before it announced awards for 15 new trials in 2002. Most comments identified how the fee-for-service payment system of US Medicare would thwart the program objectives, and, as a result, the payment system for the new trials is a monthly all-inclusive rate covering coordination with community-based services, transportation, drugs, non-covered home visits and medical equipment.13 In Australia, we have achieved reductions in heart disease mortality since the mid-1960s with a combination of prevention and treatment. This should inspire us to believe that we can do well in the future care of patients with chronic disease. Tobacco control, nutrition policies, cancer screening and preventive treatment for those with established cardiovascular disease are examples of what we have achieved to date. We now need larger injections of political will. The early prevention and better coordinated management of chronic conditions will require changes in the methods of financing and paying for healthcare, inspired and supported by strong leadership from our politicians.

Paul F Gross BE, MEngSc, MPA · Stephen R Leeder PhD, FRACP, FFAPHM · Milton J Lewis MA, PhD

Children in the new millennium. Environmental impact on health Geneva: World Health Organization, 2002 (vi + 141 pp). ISBN 92 807 2065 1. On World Health Day 2003, the World Health Organization called for “concerted action to protect three of our greatest assets: children, the environment and health”1. Dr Gro Harlem Brundtland, stated: “The biggest threats to children’s health lurk in the places that should be safest — home, school and community. Every year, over 5 million children aged 0–14 die, mainly in the developing world, from diseases related to their environments”. Children in the new millennium. Environmental impact on health presents these issues with disturbing clarity. The volume can be downloaded free from www.who.int and this site also contains a link to the Healthy Environments for Children Alliance (www.who.int/heca/en/). In just 141 pages we are presented with a depressingly pervasive summary of the key environment issues of our day, and children, especially poor children, suffer a disproportionate burden of this litany: Unsafe drinking water — two thirds of the world will live in “water-stressed” conditions by 2025. Poor hygiene and sanitation — diarrhoeal diseases have killed more children in 10 years than has armed conflict in 50 years. Catastrophic degradation of lands and fisheries — nearly 1 billion of us depend on fish for protein. Indoor and outdoor air pollution. Toxic chemicals — lifelong exposure to pesticides often starts in the womb. Warming habitats that favour insect vectors of killers such as malaria and dengue. This compendium of facts will be useful to teachers of public or environmental health. For each environmental threat the authors summarise proven remedies that can be applied at household, community, national and international levels. I would have liked more detail on the nitty gritty of negotiating multilateral environmental agreements, which must represent our best hope for their implementation. Most sobering is the realisation that nearly all of these harmful legacies bestowed on our children have their origins in human society — conflict, inequality, or our excessive and wasteful consumption. Christopher J MorganCentre for International Health Macfarlane Burnet Institute for Medical Research and Public HealthMelbourne, VIC 1. www.who.int/mediacentre/statements/2003/statement6/en/ accessed Apr 2003.

Christopher J Morgan

Objective: To determine the rate of handheld mobile telephone use among motor vehicle drivers.Design and setting: Observational study of motor vehicle drivers at three times (10:00–11:00; 14:00–15:00; 17:00–18:00) on three consecutive Fridays in October 2002 at 12 highway sites in metropolitan Melbourne.Main outcome measures: Rates of mobile phone use overall and by sex and age group, highway site (major metropolitan road, central business district, freeway exit ramp) and time of day (morning, afternoon, evening).Results: 315 of 17 023 drivers were observed using mobile phones (18.5 users/1000 drivers; 95% CI, 16.5–20.6). Men had a slightly higher rate of use (19.0; 95% CI, 16.5–21.6) than women (17.5; 95% CI, 14.1–20.9), but the difference was not significant. Older drivers (50 years or more) had a significantly lower rate (4.8; 95% CI, 2.5–7.0) than middle-aged (21.9; 95% CI, 18.8–25.1) or young drivers (23.2; 95% CI, 18.9–27.5). Central business district drivers had a slightly, but not significantly, higher rate (20.5; 95% CI, 16.8–24.3) compared with those on major metropolitan roads (16.7; 95% CI, 13.3–20.2) or freeway exit ramps (18.2; 95% CI, 14.8–21.6). The rate of mobile phone use was significantly higher in the evening (23.5; 95% CI, 19.8–27.3) compared with the morning (16.0; 95% CI, 12.6–19.4) and afternoon (15.2; 95% CI, 11.9–18.4).Conclusion: Mobile phone use is common among Melbourne metropolitan drivers despite restrictive legislation. This issue needs to be further addressed by Victoria Police and public health and education agencies. Similar research is indicated to determine the extent of mobile phone use in other states.

David McD Taylor MD, FACEM · Dianne M Bennett RN, BA · Michael Carter · Devinder Garewal

Andrew G Marsden Occupational Physician, Unit 6, 125 Melville Parade, Como, WA 6152. To the Editor: Modern air travel lends itself to aerosol transmission of viral infection. Infected individuals in modern aircraft represent a significant risk for other travellers during long journeys. In September 1999, a person with an influenza-like illness joined other workers returning by aircraft to an isolated mine in north-western Australia. He was identified as unwell by a mine supervisor in the airport lounge but was allowed to board the BAe 146 aircraft (a 75-seat passenger jet aircraft). The flight lasted 3 hours 20 minutes. On landing in the evening, most workers were transported to their quarters in a 10-minute bus trip, but some, including the affected worker, travelled independently. They then went to their individual rooms. The next day, the affected worker reported sick immediately on going to his work site and did not work for 4 days. The other workers undertook 12-hour shifts operating machinery or in offices, relatively isolated from other people. However, they may have mixed socially. Over the next 3–4 days, 15 other workers presented with an acute influenza-like illness, with fever, cough, nasal congestion, anorexia and prostration. No serological tests were undertaken because of the remoteness of the mine. All other workers on the flight were contacted by telephone 6 days after the flight. Five more were identified who had significant upper respiratory tract symptoms and were taking simple analgesics, but had continued to work. The airline reported that no staff from the aircraft had reported sick over the next week or so. The seating positions of the affected workers on the aircraft, which was full, are shown in the Box. The index patient sat in seat 11G. Most of the other affected workers appeared to sit in a “plume” around him. The only affected workers who sat further away were the supervisor who assessed the index patient in the airport lounge (seat 3A) and a person who conducted a raffle during the flight and walked the length of the aircraft collecting money and ticket stubs (seat 1F). In aircraft such as the BAe 146, air is circulated and filtered, entering the passenger compartment through continuous vents just beneath the overhead lockers, circulating downwards and exiting from continuous vents under the seats. Air therefore tends to flow in two contrarotating circles, from ceiling to floor on either side of the aircraft. Infection could well have been transmitted by aerosol droplets to passengers behind the index patient, as he coughed and sneezed throughout the flight. The immunisation status of the passengers was not recorded; most were aged 20–45 years. This outbreak was relatively confined, as the passengers were in an isolated community, and those affected were managed in their rooms. However, the implications for the spread of airborne infection in passenger aircraft and into the wider community are obvious. It must be stressed to the travelling public that people with this type of illness should not fly. Airport authorities at passenger check-ins should be encouraged to identify and formally assess potentially infected individuals, and should have the authority to take precautions against spread. Aircraft seat allocations of index patient and affected passengers I = index patient. F = passenger developed influenza-like illness. M = passenger developed mild upper respiratory tract illness.

Andrew G Marsden

The multisector approach to reducing smoking may be a good model for tackling physical activity Over the past year, the signals that physical activity is a critical community issue in Australia have become overwhelming. The increasing obesity of Australians has attracted the attention of our politicians and spawned obesity summits in New South Wales and Victoria; these both recognised that the energy expenditure imbalance (physical activity versus diet) is key to the obesity epidemic.1 Related to obesity is an inexorable increase in the prevalence of type 2 diabetes. The recent seminal Diabetes Prevention Program trial demonstrated that physical activity and dietary modification are effective lifestyle strategies for curbing this problem.2 In the area of cancer control, a notable event in the past year was the Eat and Run Conference hosted by the New South Wales Cancer Council, where evidence was presented that regular physical activity contributes to preventing colon and breast cancer.3 The past year has also seen reports that reinforce the benefits of regular physical activity in preventing coronary heart disease4 and falls in the elderly,5 and in reducing depression.6 Thus, physical activity is a pivotal public health issue, contributing to the prevention and management of at least six of Australia's seven current national health priorities: cardiovascular disease, cancer, mental health, diabetes, injury and musculoskeletal problems. However, the prevalence of inactivity in our communities is high and increasing. In 2000, 42% of Australian men and 44% of women did not partake in the levels of physical activity recommended by the National Physical Activity Guidelines (30 minutes of moderate-intensity activity, accumulated in bouts as short as 10 minutes, on most days of the week, or 20 minutes of vigorous-intensity activity on at least three days).7 These data revealed an increase in the prevalence of inactivity from 1997, when it was 37% among men and 39% among women.7 Over the past decade, there have been numerous calls for general practitioners to address physical activity and other behavioural risk factors. Along with these calls have come an increasing number of studies evaluating physical-activity interventions delivered in primary care. The National Institute of Clinical Studies (NICS) in Australia funded a systematic review of published studies, which was completed late in 2002 and included 20 studies.8 While most interventions entailed verbal advice and written information materials, they differed in scope (some targeting physical activity only, others addressing multiple risk factors); intensity (brief advice through to more intensive counselling with multiple contacts); method of delivery (physicians, nurses, health educators or exercise scientists); and target audience (all adults, older people only, interested volunteers or whole patient populations). The review concluded that there is evidence that interventions in primary care can increase physical activity in the short term. Notably, brief interventions appeared to be as likely to succeed as intensive interventions, although there was insufficient evidence to identify other attributes of successful interventions. The NICS review is one of several recent reviews that support the contribution that GP interventions can make to promoting physical activity.9,10 A notable dissenting opinion came from the recent United States Preventive Services Task Force review of clinician counselling to promote physical activity,11 but this review included only eight studies published since 1994. Overall, the level of supporting evidence for GP interventions offers encouragement. However, much still needs to be done to promote greater attention to physical activity in general practice, given that lack of time and a perceived lack of patient interest are major barriers reported by GPs.12 The NICS review offers a practical way forward in light of these barriers. It recommended brief physical-activity interventions specifically for patients with risk factors or health conditions that could be modified by increased activity. This approach should not require a major investment of time from already busy GPs and, by directing interventions to patients with current health problems that could be alleviated by physical activity, is more likely to be well received by patients. Despite the growing evidence about general practice-based physical-activity counselling, until recently there had been no efforts to disseminate intervention materials or protocols for GPs to use. However, agencies like the National Heart Foundation and the Victorian Council on Physical Activity and Health have been working with health authorities in several states to develop tools to help GPs to promote physical activity. An example of these is the Active Prescription protocol disseminated by the National Heart Foundation in NSW.13 It provides a format for delivering brief advice to patients about physical activity and also serves as a written record of this advice for doctors and patients. An electronic version has been included in the latest version of the Medical Director clinical management software (Health Communication Network, Sydney, NSW). These efforts are promising and require continued support, together with continued research on the effectiveness of the interventions, as well as dissemination strategies. Numerous social and environmental factors lead to physical inactivity in Australia. Thus, addressing this public health priority will require the sustained involvement of a range of sectors in addition to primary healthcare (eg, transport, urban development, education, sport and recreation). We can look to the past three decades of efforts to reduce smoking as an example of an integrated, multisector approach that has significantly reduced population levels of smoking. As with smoking, GPs — the preferred source of health information for most Australians — have a key role to play in promoting physical activity.

Ben J Smith PhD · Elizabeth G Eakin PhD · Adrian E Bauman PhD, FAFPHM

Objectives: To determine whether infection with human immunodeficiency virus (HIV), hepatitis B virus (HBV) or hepatitis C virus (HCV) occurred after two potential episodes of exposure through needle- and syringe-sharing in Australian prisons, and to examine use of post-exposure prophylaxis (PEP) against HIV infection in the prison setting.Design: Cohort study of potential contacts of two prisoners infected with HIV, HBV and HCV ...

Belinda G O'Sullivan MPH, GradDipAppEpi · Michael H Levy MB MS, MPH · Sharon G Barton DipApplSc · Kate A Dolan PhD · John M Kaldor PhD · Andrew E Grulich PhD · Jeffrey J Post FRACP · Dominic E Dwyer MD, FRACP, FRCPA

Differences in kava extraction methods may affect hepatotoxicity In this issue of the Journal, Gow and colleagues (page 442) report the first Australian case of fulminant hepatic failure attributed to a herbal product containing kava,1 while Moulds and Malani (page 451) note the cultural and economic importance of kava for Pacific island nations, and provide a balanced overview on kava safety and availability.2 For centuries kava has been widely consumed in Pacific island countries as a ceremonial beverage and for its mood-altering and stress-relieving properties. It is prepared as an aqueous emulsion of the crushed fresh or dried roots or lower stems of the kava shrub Piper methysticum ("intoxicating pepper").3 Pharmacological properties, such as anxiolytic activity, are attributed to a poorly characterised group of compounds termed kavalactones.3,4 In 1982, kava was introduced to some Arnhem Land Aboriginal communities from Pacific island countries, in part to reduce the harmful effects of alcohol.5 Kava use continued to rise during the 1980s and 1990s, supplied by a lucrative black market. Concerns about adverse health, social and economic effects of widespread heavy consumption resulted in the Northern Territory Kava Management Act in May 1998, which made the possession of more than 2 kg of kava illegal unless in accordance with a licence. However, an illegal trade continued, with profiteering by those distributing kava imported from several Pacific island countries. In October 2000, the Kava Management Act was amended to incorporate harm reduction objectives and a system of licensed kava supply, controlled by local Aboriginal community organisations. Over the last decade, there has been an expanding global market for herbal preparations made in Western countries and containing kava extracts.4 These products have been marketed for the treatment of anxiety, insomnia, premenstrual syndrome and stress, and sold over the counter as complementary medicines or dietary supplements.6 Since 1999, cases of severe hepatic toxicity in people using kava-containing herbal products have been reported from Europe and the United States.6,7 Subsequently, kava-based herbal products have been banned in some European countries, including the United Kingdom. In Australia, a practitioner alert and consumer advice were issued in February 2002 by the Therapeutic Goods Administration (TGA) concerning hepatotoxicity possibly related to kava-containing products. By late 2002, eight cases of liver transplantation after hepatic failure associated with use of kava-containing products had been reported from Europe, and two from the United States.6 The patient reported by Gow et al died soon after liver transplantation.1 As a result of this case, the TGA initiated a voluntary recall of all complementary medicines containing kava extracts on 15 August 2002.8 The TGA has 87 products containing kava on its Australian Register of Therapeutic Goods.8 Although details are sketchy for many of the at least 68 cases of suspected kava hepatotoxicity,4 with the herbal products sometimes containing additional ingredients, the increasing number of well documented cases1,6,7 make it likely that kava extracts are responsible for occasional severe progressive hepatotoxicity. However, the mechanism of this toxicity remains to be determined. Histological examination has shown portal inflammation with lymphocytes and eosinophils,6,7,9 and an idiosyncratic immune response to a reactive metabolite has been suggested as a possible cause.9 In two patients, phenotyping of the activity of cytochrome P450 isoform CYP2D6 showed that they were "poor metabolisers", and it was postulated that genetic differences in liver metabolism of kavalactones may be important.9 Moulds and Malani discuss the paradox that fulminant hepatic failure has not been documented with traditional kava use in Pacific countries.2 Kavalactones in herbal products are usually extracted with ethanol or acetone,6 and may differ critically from the aqueously extracted kavalactones used in Pacific countries and Aboriginal communities. Of note is an early study of the health effects of kava use in Aboriginal communities, which documented consistent abnormalities in liver function tests in heavy kava drinkers.5 A recent study in Arnhem Land has confirmed these findings, with abnormal serum levels of γ-glutamyl transferase (GGT) and alkaline phosphatase (ALP) in 61% and 50% of kava users, respectively.10 However, serum levels of alanine aminotransferase (ALT) were not raised in any kava drinkers. Furthermore, the abnormalities in liver function usually return to normal within 1–2 months of stopping kava use.10 The raised GGT and ALP levels combined with normal ALT levels in Aboriginal kava users do not suggest acute inflammation and are not consistent with the changes documented in the cases of hepatotoxicity associated with herbal products, where aminotransferase levels are especially high.1,6,7 Clinical surveillance in the Northern Territory over 20 years has not documented any cases of fulminant hepatic failure attributable to kava use. This is despite Aboriginal kava drinkers consuming kavalactones in doses estimated to be 10–50 times the recommended therapeutic doses for herbal products.3 However, the recent study confirmed adverse effects of kava, such as kava dermopathy and lymphocytopenia,10 which were documented in the 1980s.5 Although a rigorous systematic review found kava to be an effective symptomatic treatment option for anxiety,4 herbal preparations should not be used until the mechanism for hepatic toxicity is clearly ascertained. The abnormal but reversible GGT and ALP levels seen in heavy kava drinkers does not reflect the same pathological process. Whether the apparently idiosyncratic fulminant hepatic failure documented with herbal kava preparations can also occur with traditional aqueous extracts requires further surveillance. Close monitoring for this and other potential adverse effects of kava use in Aboriginal communities and Pacific countries is recommended, in addition to initiatives encouraging moderation in consumption.

Bart J Currie FRACP, DTMTH · Alan R Clough MSc

The overarching cause is energy imbalance The health and wellbeing of Australia's children and adolescents, now and in the future, is under threat. In 2002–2003, the most prevalent child health issues affecting children are preventable: obesity, dental disease, emotional and behavioural problems, bullying and learning delays. These problems often present as comorbidities. Overweight and obesity affect about 23% of Australian children and adolescents, with 6% being obese.1 These are conservative estimates, as there has been no systematic monitoring of the prevalence of overweight and obesity in Australian children and adolescents since 1995. However, over the previous decade, the prevalence of overweight children almost doubled, and the prevalence of obese children more than tripled.1,2 There is no reason to believe that the rapid rise in prevalence rates has not continued. Studies of historical datasets have also revealed that the prevalence of overweight and obesity in children and adolescents doubled over the period 1985–1997, a far greater rate of increase than in the preceding 16 years.3 Health inequalities related to overweight and obesity are evident. There is a higher incidence of overweight and obesity in children of parents of particular backgrounds,3 and maternal education is the strongest social determinant of overweight and obesity in childhood.4 Although there are limited national data, and combined New South Wales, Victorian and National Nutrition datasets1 failed to find a rural/urban difference, Victorian epidemiological data show a statistically significant, higher proportion of overweight and obese boys in metropolitan areas, but this difference was not found for girls (Ms K Hesketh, NHMRC PhD Scholar, Centre for Community Child Health, Melbourne, VIC, personal communication). The health consequences of overweight and obesity are substantial, although Australian data remain unclear in certain areas.5 At least in the United States, obesity carries more stigma in children than any physical disability, and this is evident across all socioeconomic and ethnic groups.6 Issues of social acceptance, athletic competence and physical appearance are well known to obese children and affect their sense of social and psychological wellbeing. Obese children with decreasing self-esteem are more likely to smoke and drink alcohol compared with those whose self-esteem increases or remains the same.7 Obese children and adolescents may also have a range of medical conditions including hypertension, dyslipidaemia, and even type 2 diabetes. Other problems, such as musculoskeletal discomfort, obstructive sleep apnoea, heat intolerance, asthma and shortness of breath, greatly affect their lifestyle.8 Implications for the future can be gathered from longitudinal studies. Combined cohort studies indicate that relative body weight is sustained from childhood to adulthood, and, once children or adolescents are overweight or obese, their weight is unlikely to track backwards.5 If this is not sufficient reason for concern, reflect that these studies (of the long-term consequences of child and adolescent obesity) were all performed before the worldwide obesity epidemic developed. What, then, will be the outcome, in 10 or 20 years' time, of large numbers of children and adolescents entering adulthood, already with abdominal obesity and well established risk factors for cardiovascular disease and type 2 diabetes? Focusing on children highlights their contribution to contemporary society and future populations. Addressing the determinants of health and wellbeing for children and adolescents will improve population health and wellbeing overall. The overarching cause of the obesity epidemic is energy imbalance — a relative increase in energy intake (food intake) together with a decrease in energy expenditure (decreased physical activity and increased sedentary behaviour). Identifying the most important predictive determin-ants of each of these behaviours, as well as the most effective and sustainable remedial strategies, is complex and involves parental education and employment; housing environments; play, recreation and physical activity; food and nutrition; accessible active transport; and child-friendly physical and social environments.9 Some simple trends suggest relatively amenable remedies. Children's fruit and vegetable consumption has decreased over the past 20 years. Their physically active time has also decreased, while time spent in sedentary activities such as television watching and computer games has increased. Finally, consumption of energy-dense foods (including sweet soft-drinks and snack bars with a high sugar content) has increased. Possible remedies include: parental education strategies regarding healthy food choices, activity options, obesity trends, as well as supportive behavioural change strategies; supportive policies and environments in the places children and families spend their time (child care, school, workplaces, home, local neighbourhoods); and prioritisation of free time for physical activities. Evidence from controlled trials (although these trials are heterogeneous as regards the age groups and settings studied) highlights the potential for school-based programs that promote physical activity, modify dietary intake and reduce sedentary behaviours. However, recent qualitative research indicates that differences in outcomes will only be achieved if sustainable changes involve all generations, tackle the widely held beliefs regarding eating and activity,10 involve population-wide health promotion messages, and dispel myths such as children's overweight being just "puppy fat". Further, there are environmental aspects that are well beyond an individual family's ability to modify, including: regulation of marketing of unhealthy food choices for children; provision of safe, cheap and accessible public transport; and urban planning initiatives that give priority to child-friendly and pedestrian-friendly environments. The latter options are more controversial, and vested interests may seek to cloud the community's perceptions of factors driving the overweight epidemic. We need to actively involve industry in partnerships for environmental change. Health practitioners working in the community, child and family nurses and general practitioners are crucial in any comprehensive strategies, as they provide a widely available service to families and can tailor specific strategies for individual families.11,12

Elizabeth B Waters MPH, DPhil · Louise A Baur PhD, FRACP

Objective: To measure the prevalence of obesity in Australian adults and to examine the associations of obesity with socioeconomic and lifestyle factors.Design: AusDiab, a cross-sectional study conducted between May 1999 and December 2000, involved participants from 42 randomly selected districts throughout Australia.Participants: Of 20 347 eligible people aged > 25 years who completed a household interview, 11 247 attended the physical examination at local survey sites (response rate, 55%).Main outcome measures: Overweight and obesity defined by body mass index (BMI; kg/m2) and waist circumference (cm); sociodemographic factors (including smoking, physical activity and television viewing time).Results: The prevalence of overweight and obesity (BMI > 25.0 kg/m2; waist circumference > 80.0 cm [women] or > 94.0 cm [men]) in both sexes was almost 60%, defined by either BMI or waist circumference. The prevalence of obesity was 2.5 times higher than in 1980. Using waist circumference, the prevalence of obesity was higher in women than men (34.1% v 26.8%; P < 0.01). Lower educational status, higher television viewing time and lower physical activity time were each strongly associated with obesity, with television viewing time showing a stronger relationship than physical activity time.Conclusions: The prevalence of obesity in Australia has more than doubled in the past 20 years. Strong positive associations between obesity and each of television viewing time and lower physical activity time confirm the influence of sedentary lifestyles on obesity, and underline the potential benefits of reducing sedentary behaviour, as well as increasing physical activity, to curb the obesity epidemic.

Adrian J Cameron MPH · Paul Z Zimmet MD, FRACP, FAFPHM · David W Dunstan PhD · Marita Dalton GradDipEpidemiol · Jonathan E Shaw MD, MRCP · Timothy A Welborn MB BS, PhD · Neville Owen PhD · Jo Salmon PhD · Damien Jolley MSc

Objective: To determine whether warming or rubbing adult diphtheria tetanus (ADT) vaccine immediately before administration affects its temperature and reduces the incidence of pain.Design: Double-blind, randomised controlled trial and in-vitro temperature study.Setting: Emergency department (ED) of a regional hospital between April and December 2001.Patients: Convenience sample of 150 patients aged 16 years or over who presented to the ED requiring ADT booster vaccination.Intervention: Patients were randomised to receive vaccine that was "cold" (no deliberate warming), "rubbed" between the palms for 1 minute, or "warmed" in a 37°C incubator; vaccine was administered as recommended in Australian guidelines.Main outcome measures: Incidence of pain and pain score on McGill Present Pain Intensity Questionnaire at 5 minutes, 24 hours and 48 hours after injection; and temperature of vaccine after preparation for simulated administration.Results: The "cold" vaccine had significantly lower temperature (mean, 19.1°C; 95% CI, 17.5–20.7°C) than the "warmed" vaccine (mean, 28.9°C; 95% CI, 28.4–29.4oC) and "rubbed" vaccine (mean, 26.9°C; 95% CI, 24.5–29.3°C). There was no significant difference in incidence of pain between the groups who received vaccine prepared in different ways at any follow-up (5 min: P = 0.62; 24 h: P = 0.58; 48 h: P = 0.61) or overall (P = 0.99). Among those who completed follow-up, incidence of pain at any time was 77/138 (56%); there was no difference in their time-averaged pain scores (P = 0.63) or peak pain scores (P = 0.60).Conclusions: Warming or rubbing ADT vaccine does not reduce the incidence of pain after administration. Regardless of how ADT vaccine is prepared, its temperature approaches ambient by the time it is injected.

Matthew J Maiden BSc, BM BS, DRANZCOG · Gregory N Benton RN, CCRN · Russell A Bourne MB BS(Hons), FANZCA

To the Editor: Figures from the Australian Bureau of Statistics show that Australians make about 3.3 million overseas departures each year.1 Few data are published on the extent to which Australian travellers seek pre-travel health advice, what vaccinations they receive, and what risks they are exposed to during travel. A series of surveys of travellers examining these questions has been conducted under the auspices of the Travel Health Advisory Group, a coalition of Australian travel and medical organisations. Surveys were conducted in 1996, 1997, 2000, 2001 and 2002. On each occasion, a market research company telephoned people from mainland capitals using numbers randomly selected from the telephone directory. This process continued until 500 people aged 18 or over who had travelled overseas in the previous two years had been interviewed. In the 2002 survey, about 10 000 calls were made to complete the interviews. The questions on vaccinations focused on hepatitis A and B, two of the most common vaccine-preventable diseases associated with travel.2 Results from the 2002 survey are shown in the Box. A minority of people (31%) reported seeing a doctor or travel clinic for pre-travel health advice. Of those who saw a doctor or travel clinic, 31% did so two weeks or less before departure. Over the series of surveys, there has been an increase in travel to destinations with high- or intermediate-risk for hepatitis A infection, from 40% of travellers in 1996 to 58% in 2002. Despite this increase, only a minority of travellers could recall ever being vaccinated for this illness. Travellers were informed about how they might be exposed to hepatitis A and B and asked if they believed that they could have been at risk during their most recent overseas trip. Substantial numbers recalled a risk (34% and 16% for hepatitis A and B, respectively) and some of these could not recall being vaccinated (18% and 7%, respectively) (Box). These surveys have methodological limitations, including lack of information on the consent rate and potential recall bias. However, the results suggest that substantial numbers of travellers do not seek pre-travel health advice and are at risk of vaccine-preventable diseases during travel. Not only does this have implications for individual travellers, it also creates public health risks, as travellers can introduce hepatitis A and B into their home communities. These results suggest more public education is needed about the importance of pre-travel health advice and appropriate vaccination. Results of 2002 survey of Australian travellers overseas Variable No. of travellers (n = 500) Age (years) 18–29 156 (31%) 30–49 188 (38%) ≥ 50 153 (31%) Not stated 3 (0.6%) Male sex 205 (41%) Hepatitis A risk in country visited* High 226 (45%) Intermediate 62 (12%) Low 212 (42%) Sought pre-travel health advice from doctor or travel clinic Doctor 135 (27%) Travel clinic 20 (4%) No professional advice 345 (69%) Believed could have been at risk of hepatitis on most recent trip Hepatitis A 168 (34%) Hepatitis B 79 (16%) Vaccinated against hepatitis Hepatitis A 195 (39%) Hepatitis B 197 (39%) Believed at risk of hepatitis on most recent trip and not vaccinated or unsure Hepatitis A 91 (18%) Hepatitis B 36 (7%) Hepatitis A risk in country visited* among those not vaccinated for hepatitis A or unsure High 123 (25%) Intermediate 40 (8%) Low 142 (28%) * As defined by the United States Centers for Disease Control and Prevention, 2000.3 Destinations for the cohort of 500 were Asia (45%), northern Europe (28%), southern Europe (14%), North America (15%), Oceania (14%), eastern Europe (3%), Africa (3%), Middle East (2%), South America (1%) and Central America (1%), with some having more than one destination.

Nicholas A Zwar

The anti-smoking crusade in Australia is in a sorry state, say the leaders of California's Tobacco Control Program Fear comes in many forms. At the turn of the 20th century, our grandparents were terrified by tuberculosis and polio (to mention only a few of the hideous communicable diseases that plagued the human race). We pulled out all the stops and gladly spent millions to "conquer" the responsible infective agents, at least in the resource-rich nations. As a result, the "plagues" which now terrorise the industrialised world are cardiovascular disease and cancer. These two categories of disease alone are responsible for a majority of all deaths, illnesses, disabilities and the lion's share of medical care costs. The leading responsible agent for these is tobacco. Yet, we tolerate this agent, subsidise it with government funds, and passively accept the tobacco industry argument that our societal ethos accepts its use (that is, it's "normal" and "expected"), and those who oppose its use are, by implication, "intolerant" and "puritanical". There are few examples of so deadly an error in human history. We need to recognise that this problem is caused by an agent (tobacco) as virulent as the tubercule bacillus or the poliovirus. Furthermore, this agent is being skilfully marketed by an industry which is, sans hyperbole, an immensely profitable organisation that has grown by strategically buying social and political influence. An egregious example of this is the relationship between the big tobacco lobbyists and most of the major political parties in Australia.1 Tobacco use remains the single largest underlying preventable cause of death in Australia. The tragic irony is that these deaths are so very preventable. Yet tobacco control measures in Australia have stalled, primarily due to a monumental paucity of funds and political will. Sadly, the Australian crusade is actually a non-crusade. Because of complacency, you are falling far short of what could be achieved if you were once again to become global leaders in tobacco control. Needless to say, tobacco companies are constantly and very effectively working behind the scenes to diminish the gains that have been made to date. Tobacco use in Australia will probably fail to decline, and could even increase, unless a proactive campaign to regenerate your flagging efforts is undertaken. To that end the Cancer Council of New South Wales invited us to visit in November 2002 to transfer some of the California Tobacco Control Program's expertise, irreverence, passion and technology to our Australian counterparts. From 1988 (the year before the California program was launched) to 2001, annual per capita consumption of cigarettes in California declined by 60% to 50 packs per capita. During the same period, annual per capita consumption in the entire nation (including California) declined by only 34%, to just over 100 packets per capita (twice the rate in California).2 The comparable statistic for Australia is currently derived to be about 75 packs per capita annually. From 1988 to 1997, the decline in lung and bronchial cancer rates in California was five times the rate of the decline in the rest of the nation.3 Furthermore, prevalence rates of youth tobacco use in California declined 47% (from 11.2% in 1997 to 5.9% in 2001).4 What worked in California will also work in Australia. The California experience demonstrates that a comprehensive approach designed to change social norms and expectations around tobacco use will reduce both its use and tobacco-related morbidity and mortality. This approach involves media-supported advocacy for laws and voluntary policies that discourage tobacco use, especially at the community level. The objective of this approach is to change the social environment in such a way as to make tobacco use less desirable, less acceptable, and less accessible to adults and youth. The four broad priority areas, or policy themes, of the California program are: Protecting people from exposure to secondhand tobacco smoke; Exposing and countering tobacco industry influences in Californian communities; Reducing the availability of tobacco by regulating tobacco retailers; and Providing support for smoking cessation services. Having studied the dynamics of your political and governmental system, we identified four areas for Australia to work on. Firstly, the insidious influence of the tobacco industry on both sides of your parliamentary aisle is a huge drawback. The fact that a former premier of New South Wales is currently the chairman of your biggest tobacco company says it all. Secondly, your allocation of funds to tobacco control is ludicrous. Our largest State, California, has spent over US$1 billion in 12 years to achieve these results. In your largest State, New South Wales, you spent less than US$2 million last year. Thirdly, your governmental bureaucracy needs to be infinitely more agile and aggressive. Throughout our trip, we were complacently assured by government officials that some of these interventions "would not work" in Australia. We used to hear the same arguments in California. We just ignored them and pushed ahead aggressively to become the first major governmental organisation to take this "legally constituted tobacco industry" head on, by publicly ridiculing them for their falsehoods (as to the addictive, atherogenic, mutagenic and carcinogenic properties of tobacco smoke) and questioning their amoral marketing practices. You must give the leaders of your tobacco control program permission to be caustically critical of the tobacco industry and its surrogates as an official government policy. Lastly, your constituency of anti-tobacco control advocates is too civil by far. Even as we enjoyed success after success, we were continuously and usefully criticised, prodded and even pilloried by an ever-vigilant anti-tobacco constituency to do more and more, to good avail. In expressing these criticisms, we speak as respectful co-labourers in the field of tobacco control. Our own efforts were inspired by Australia's pioneering initiatives in tobacco control 20 years ago. Australia has had phenomenal success in the implementation of certain measures like advertising bans and point-of-sale restrictions (price and pack warnings being good examples of these), but none of these is a fundamental threat to the operation of the industry. Thus, having seen your once-proud effort diminished considerably, we have ventured to speak frankly in the hope that this may contribute to restoring your tobacco control efforts to their former glory. Our best advice? The allocation of funds to tobacco control in Australia is negligent, bordering on the farcical. At a minimum, you have to spend $50 million per year in New South Wales and well over twice that for all of Australia. This could fund an aggressive tobacco control program capable of producing a sea change in community norms around tobacco use. Your focus should be on increasing the tax on all tobacco products, as well as promulgating a total ban on smoking in all indoor venues, including bars, pubs and clubs. Smoking bans are, contrary to the tobacco industry's propaganda, good for health reasons, good for business, and good politics, as has been amply illustrated in California.5-7 A key point to remember is that a good adult campaign is also a good youth campaign. There is a clear divide between your political leaders "cosying up to" the tobacco industry and the preferences of your population, as expressed by polling and survey data.8-10 During our visit, we were repeatedly confronted with the question as to why your political leaders were not responding to these expressed needs. In conclusion, we do not delude ourselves that this will be easy to achieve given the organised opposition of the monolithic tobacco industry behemoth and its front groups and political influence in Australia. However, there is no shortage of anti-tobacco control expertise in Australia, where some of the world's leading tobacco control experts reside. You have the talent and technical expertise for an effective program. So, why are Australian authorities emulating the ostrich and sticking their heads in the sand? The anti-tobacco constituency needs to sound the clarion call: "In tobacco control in Australia: what aren't we doing and why aren't we doing it?".

Dileep G Bal MD, MS, MPH · Donald O Lyman MD, DT, DTPH · David F Veneziano MPA

To the Editor: A recent MJA article by Kjellstrom et al1 correctly lists home heating using wood as a major cause of air pollution in Australia. It is therefore surprising to read in their optimistic view of "Circa 2100" that, whereas coal will be burnt in superefficient and clean-burning electric power stations, more wood will be burnt to heat houses. When the Irish government banned the sale of coal in Dublin, there were substantial decreases in smoke pollution and mortality from respiratory and cardiovascular causes.2 If any evidence is needed that similar benefits can be expected from banning domestic wood heaters, it is to be found in recent research on the emission of fine particles and a wide range of toxic compounds by wood heaters, old and modern.3 The reason given by Kjellstrom et al for regarding wood-burning for home heating as desirable is that it would cause less global warming. But this reason is not convincing, as the potential "benefit" would be outweighed by the immediate harm inflicted by wood smoke on public health. People are unlikely to agree that we have to accept death and disease now in order to save the planet a few decades hence. It is commonly claimed that the burning of wood is "greenhouse-neutral". This is not true if the burning takes place in home heaters, which emit methane and soot particles — both powerful greenhouse agents. When global emission rates and global warming potentials are both taken into account, the probable ranking of the three most important greenhouse agents is (first) carbon dioxide, (second) soot particles, and (third) methane.4 As almost everything in greenhouse science is fraught with high uncertainty, it is not possible to say what percentage of the potential greenhouse advantage of wood heaters is cancelled by their emission of soot particles and methane. What can be said is that firing superefficient and clean-burning electric power stations with plantation timber is the best way to burn wood, using the greenhouse advantage without the toxic hazard.

Louis A du Plessis

Photograph courtesy Ray Sherman To the Editor: I read with interest the entry in "In other Journals" entitled "Beware the zebra".1 It described a study in the United States (reported in JAMA)2 which found that elderly people were more likely to be struck by a motor vehicle when crossing at a marked crossing than at an unmarked site! Personal observation after a year of living and working in the States has led me to be no longer surprised by such a report. There is what I believe to be a culturally different attitude to road safety here. There seems to be a general belief by pedestrians that cars will stop if they walk out on to the road — often without looking. This is more so at marked crossings, where I can attest to the findings of the article that "nearly 40% of pedestrians incorrectly believed that traffic must stop for a pedestrian who is on the curb waiting to cross at a marked crosswalk." I believe that this perception may have been ingrained from an early age — US school buses have stop signs which appear when the bus stops, so that traffic behind the bus, alongside and in the opposing lanes has to stop while children are getting on or off the bus and then crossing the road. There is little attempt by the schoolchildren to "look both ways", as we were taught when growing up. This, I think, leads to a misperception that traffic will stop for all pedestrians, who may feel even more entitled at a marked crossing to cross without looking. Since the report may have horrified some readers, I thought it might be worth providing a little local experience on the subject!

Pedita S Rowe

Despite the risks to unvaccinated children, compulsory vaccination is not the answer In a pluralistic society, there are many views on what constitutes acceptable child-rearing. In Australia and other Western societies, parental discretion is limited primarily by legislation against abuse or neglect. In treatment decisions, the legal starting point is that the united view of both parents is correct in identifying the child's welfare. A court will usually only override the parents' decision if the judge is convinced the child's life is endangered, such as when a child needs transfusion.2 Administration of a vaccine is never immediately life-saving in this sense, except in the case of post-exposure rabies vaccine,3 but vaccination satisfies ethical criteria for preventive interventions in children: it is effective, minimally invasive, and associated with significant societal benefits.3 Indeed, the highly favourable benefit-to-risk ratio of childhood vaccination is so well documented that healthcare professionals are understandably frustrated when faced with what seems to be an irrational decision by parents to refuse vaccination. This is especially so when this decision has resulted in failure to prevent a life-threatening illness, as in the tetanus case presented by Goldwater et al (page 175).4 This case raises issues for both the clinician and society. How do healthcare professionals understand and best respond to a conscious decision not to vaccinate? In a highly immunised population, what is the balance of risks and benefits to individual children and their contacts from refusal to vaccinate? Should a case such as this propel us towards compulsory vaccination? In Australia, vaccination is not compulsory, but various incentives and reminders aim to promote it. First, payment of the maternity allowance at 18 months and the childcare benefit requires up-to-date vaccination according to the Australian Childhood Immunisation Register (ACIR),5 unless a medical practitioner has notified the ACIR of a contraindication or serologically confirmed immunity, or has discussed conscientious objection with a parent. Second, at school entry, documentation of full vaccination is required in most Australian jurisdictions, with children who do not have such documentation or serological proof of immunity to specific diseases, such as measles, able to be excluded from school attendance if suspected cases occur. Although the United States is often quoted as having laws for mandatory vaccination, the practical effect of these laws is also limited to exclusion of unvaccinated children from school during outbreaks, although preschool attendance for such children can be barred altogether.6 Italy is one of a few countries where there is compulsory vaccination, but only for diphtheria, tetanus, polio and hepatitis B. However, this has not been enforced for many years.7 To find examples of truly compulsory vaccination, it is necessary to go back to the 19th century. In England, the Vaccination Act of 1853 made smallpox vaccination compulsory for all infants in the first three months of life, on pain of fine or imprisonment. Its enactment spawned riots in several towns and an active anti-vaccination movement. In 1898, a new Vaccination Act removed these penalties and introduced the concept of "conscientious objector" into English law.8 In present-day Australia, most parents whose children are not fully vaccinated are not conscientious objectors, but rather face practical barriers such as recurrent minor illness, work commitments, large family size or social disadvantage.9,10 Parents who are strongly opposed to vaccination comprise a much smaller group. Of a large sample of 1779 Melbourne children in childcare in 1997, only 13 (0.7%) had not received any vaccines.10 This is similar to the proportion of all children Australia-wide registered with Medicare for whom there is a registered conscientious objection.5 In general, such parents tend to be well educated, older, female and of Anglo-Saxon background.11,12 Qualitative data suggest that conscientious objectors fear possible but unknown, especially long term, adverse effects of vaccines, believe that lifestyle measures to improve general immunity are viable alternatives to protection from vaccines, and often mistrust the motives of healthcare providers.9,12 This limits the ability of healthcare professionals to present pertinent counterarguments. Indeed, there is some evidence that parents philosophically opposed to vaccination may have their objections reinforced by factual information about risks and benefits, because these facts do not accord with their beliefs about health and illness.13 In contrast, parents who are merely doubtful about vaccination are much more likely to be amenable to presentation of relevant factual information.9 Healthcare professionals communicating with such doubtful parents need to have their facts well prepared and be sure that they have ascertained the parents' specific concerns, particularly whether these arise from personal or family experience. This is all potentially achievable within a realistic timeframe for a standard consultation, using readily available material specific to Australia.14 In the current Australian environment of high immunisation rates, does refusal of vaccination pose risks to either the individual or the community? In the case of tetanus, the risk is limited to the individual, as the disease is not transmissible. The risk to the individual is highlighted by the US experience, where, with very high immunisation rates, 15 reported cases of childhood tetanus occurred between 1992 and 2000.15 Children unvaccinated because of their parents' beliefs accounted for 9/11 cases in school-aged children,15 although objecting families represent only 0.6% of families with children attending school in the US.16 For other transmissible vaccine-preventable diseases, such as measles, pertussis and poliomyelitis, the risk goes beyond the individual. In Colorado, schools with a higher percentage of objectors were more likely to have a pertussis outbreak, and at least 11% of vaccinated children in measles outbreaks acquired measles from contact with an unvaccinated child of objecting parents. In addition, there was a 22-fold (measles) and sixfold (pertussis) increased risk for the individual unvaccinated child.16 Similarly, in Germany, almost all cases of Hib meningitis occur in unvaccinated children of objecting parents.17 In closed communities of vaccination objectors, such as certain religious groups, very high levels of morbidity from diseases not present in the general community can occur, such as in polio outbreaks in the Netherlands.18 Although there are few such communities in Australia, there is a tendency for conscientious objectors to cluster in certain geographic areas, so the risk of transmission is amplified. Measles cases in Australia now arise exclusively from imported strains and the unvaccinated children of conscientious objectors have recently been highlighted as at risk.19 Parents should be made aware that a decision not to vaccinate, made on their children's behalf, exposes their child to significant risks, even in 2003. Persuasion, at both the clinical level14 and the societal level,5 is appropriate, but truly compulsory vaccination is not an option, either in Australia or in other comparable countries.6,7

Peter B McIntyre FRACP, FAFPHM · Alison H Williams MB BS, FRACGP · Julie E Leask RM, MPH

Re the article "Water and the environment: a natural resource or a limited luxury?", by Karin Leder, Martha I Sinclair and John J McNeil in the 2/16 December issue of the Journal (Med J Aust 2002; 177: 609-613). Due to a software error, the affiliation of the authors was incorrectly given as the National Centre for Epidemiology and Population Health, Australian National University, Acton, ACT. The correct affiliation and contact details are: Department of Epidemiology and Preventive Medicine, Monash University – Central and Eastern Clinical School, Alfred Hospital, Melbourne, VIC. Karin Leder, FRACP, MPH, DTHM, Head of Infectious Disease Epidemiology; Martha I Sinclair, PhD, Senior Research Fellow; John J McNeil, FRACP, PHD, FAFPHM, Head of Department. Correspondence: Dr Karin Leder, Department of Epidemiology and Preventive Medicine, Monash University – Central and Eastern Clinical School, Alfred Hospital, Commercial Road, Melbourne, VIC 3004. karin.lederATmed.monash.edu.au The html and pdf versions of the article available on this website have been corrected.

Karin Leder FRACP, MPH, DTHM · Martha I Sinclair PhD · John J McNeil FRACP, PHD, FAFPHM

In reply: The support for my study1 is pleasing, especially the letter from Martin. I agree with Hockey and Pitt that including Queensland data would have enhanced my study, as Queensland is the only other Australian State with a substantial injury database like South Australia's and Victoria's. However, when I analysed the Queensland data only around 1% of baby-walker injuries could be classified as "proximity", compared with 20%–25% in Adelaide and Melbourne. Surveillance collection can very easily miss critical details. The SA questionnaire asks "What was the victim doing at the time of the injury?", then "What went wrong?" and, finally, "How exactly was the injury caused?". As an example, "a child in a baby walker accesses the fireplace and burns her hand". If one or two of the above questions are left out, or the coder does not capture all the detail, this narrative easily becomes "child burns hand on fireplace" and the detail that the baby walker facilitated the child's access to the fireplace is lost. In 1995, after the Victorian Injury Surveillance System moved to a "minimum" dataset, their "proximity" component dropped to just 1%, the same as for Queensland. Analysts at the Victorian Injury Surveillance System recommended that these post-1995 data not be used for my study. In my opinion the Queensland system has the same systematic problem, and discussions with Hockey suggest that this is a possibility (Richard Hockey, Senior Data Analyst, Queensland Injury Surveillance Unit, personal communication). My assertion — that the data I used are largely representative of baby walker injury events in metropolitan Australia — is justified, as any variations in "proximity" rates (even if they do exist) caused by different architectural styles in Queensland would represent only a very small proportion of the events Australia-wide. The presence of additional steps and higher steps would only explain a higher proportion of these types of injuries, and possibly increased severity, but not the almost total absence of "proximity" injuries, as there is no association between them. The recent finding by the US Consumer Product Safety Commission2 that steps and stairs injuries still occur with new-style walkers confirms the need to discontinue the proposed mandatory regulations and instigate an immediate ban. The letter from Beard is disturbing in its attitude. Inadequate supervision is another name for victim blaming, and an unsafe environment is a perfect description of a baby walker. Moreover, to suggest that the ban would include any form of purpose-designed apparatus, including a commercial baby walker, to assist disabled children is nonsense.

Peter G Thompson

The US strain of West Nile virus could enter Australia, but we may be protected by the already present Kunjin virus Australia needs to consider the implications of the recent emergence and spread of West Nile virus in the United States, including the possibility of its spread to Australia. This development also raises questions about Kunjin virus, a subtype of West Nile virus, which already occurs widely in Australia. West Nile virus, a mosquito-borne flavivirus, was known to have a wide geographic range, extending from Africa through the Middle East to southern and eastern Europe and western Asia. The initial outbreak in New York city and adjacent counties in August 1999 resulted in 62 human infections and seven deaths of elderly patients.1,2 Genetic evidence suggests that the virus came from the Middle East. Over the next three years, it spread rapidly in the US, first in the north-east and then more widely, causing disease and deaths in humans, horses and birds.3 Birds, especially crows, were found to be responsible for both spread and maintenance of the virus in a natural cycle with culicine mosquitoes.3,4 By late November 2002, the virus had been detected in 43 states spanning the mainland US, with 3735 reported clinical cases and 215 deaths, almost all among the elderly.5 The virus had also spread to five provinces in Canada, with around 140 cases and two deaths. The speed of its spread was undoubtedly due to the presence of competent mosquito species and a large number of susceptible birds, and especially to a greatly increased propensity to spread in a virgin ecosystem. Before 1996, West Nile virus was known to cause high fever, chills, malaise, headache, backache, arthralgia, myalgia and retro-orbital pain, and, in about 50% of cases, a maculopapular rash,6 but neurological symptoms were uncommon. Since then, severe neurological illness, including encephalitis and meningitis, has been reported more frequently,6,7 together with an acute flaccid paralysis syndrome.6,8 Fatalities have generally been in the elderly. Although human acquisition is nearly always through the bite of an infected mosquito, unusual modes of transmission via organ transplantation,9 blood transfusion9,10 and possibly breastfeeding11 have recently been described in the US. West Nile virus is closely related antigenically and genetically to other members of the Japanese encephalitis serological group of flaviviruses, including Japanese encephalitis, Murray Valley encephalitis (MVE), and St Louis encephalitis viruses, and is almost identical genetically and immunologically to Kunjin virus.12 Kunjin virus, reclassified as a subtype of West Nile virus in 2000, is the most common flavivirus in Australia, occurring widely across northern Australia. Most infections with this virus are asymptomatic, but it causes occasional, mild febrile illness, similar to that traditionally described for West Nile virus, and rare cases of non-fatal encephalitis.13 It is closely related genetically to the West Nile strain in North America,1,2 both being members of West Nile lineage 1. However, unlike Kunjin virus, some recently isolated members of West Nile lineage 1 are known to cause fatal encephalitis in elderly patients,3,6,7 fatal disease in wild birds (in North America)3,14 and domestic geese (in Israel),15 and severe epizootics in horses, with significant mortality.7,13,14 In addition, recent experimental evidence has shown that the New York strain of West Nile virus is considerably more neuroinvasive than Kunjin virus.16 Could Kunjin virus mutate to be as virulent as recent West Nile strains seen in Europe and the US? Kunjin virus has been in our ecological system for many years without any apparent increase in virulence. Several mutations may be required to increase virulence substantially, and there seems little pressure to select for such mutations. Alternatively, could a more pathogenic strain of West Nile virus spread to Australia and, if it did, would it be able to establish itself in competition with Kunjin virus? West Nile virus has been isolated in Sarawak, Malaysia, and is endemic in western India; thus, it could conceivably spread slowly through the region. The virus is believed to have reached New York through carriage on an aircraft of an infected mosquito or an infected traveller with sufficient viraemia to infect a mosquito on arrival in the US. Similar mechanisms could allow its importation into Australia from the US, Europe or Africa. Although current disinsection procedures for aircraft are believed to minimise the first possibility, there is concern that an infected human traveller arriving in Australia might have sufficient viraemia to infect Australian mosquitoes. More information is urgently needed on viraemia levels during infection so that this risk can be properly assessed. Other routes of entry seem less likely. Although a horse infected with West Nile virus was recently imported into Australia from North America, viraemia levels in horses are believed to be insufficient to infect mosquitoes. Introduction of virus through migratory birds is doubtful because of the route and length of migration. Even if West Nile virus is introduced into Australia, it would have to compete with Kunjin virus for vertebrate hosts and vectors. Experience with other members of the Japanese encephalitis serogroup of flaviviruses suggests that they do not interfere with each other's ability to spread,12 despite the induction of cross-reacting antibodies. Thus, West Nile and Japanese encephalitis viruses coexist in western India, and MVE and Kunjin viruses coexist in Australia, while West Nile and St Louis encephalitis viruses appear to coexist in North America, and Japanese encephalitis and MVE viruses appear to coexist in Papua New Guinea. However, antibodies to Kunjin virus neutralise West Nile virus (and vice versa), and Kunjin virus is widely distributed over much of Australia, so it may prove more difficult for West Nile virus to find the susceptible vertebrate hosts it needs to become established or to spread rapidly. There is no treatment or vaccine available for West Nile infection, but people with prior exposure to Kunjin virus should be protected. Similarly, those exposed to other members of the Japanese encephalitis serological group, especially Japanese encephalitis and MVE viruses, may have limited protection against West Nile disease. The current Japanese encephalitis vaccine is unlikely to protect, although more research is needed to confirm this.17,18 Finally, could Japanese encephalitis virus spread in Australia as West Nile virus has done in the US? Japanese encephalitis virus has occurred in the Torres Strait of northern Australia nearly every year since 1995, and entered the Australian mainland in 1998.19,20 As Australia has the appropriate mosquitoes and avian and porcine vertebrate hosts for natural transmission cycles,20 it is likely that Japanese encephalitis virus will eventually become established here. However, the narrow range of bird species used by Japanese encephalitis virus as maintenance hosts (generally herons and egrets), the need for pigs as amplifier hosts, as well as the Australian ecosystem, climate and arid interior, would suggest that Japanese encephalitis virus is unlikely to match the spread of West Nile virus in North America. Migratory birds, wind-blown insects and rapid air transport of infected humans, animals and insects could all bring exotic pathogens into Australia. Identifying potential threats, maintaining aircraft disinsection and mosquito surveillance around major airports, as well as good internal surveillance, are important parts of the protection of human and animal health in this country.

John S Mackenzie BSc, PhD · Roy A Hall BSc, PhD · David W Smith FRCPA

Australia is one of the healthiest countries in the world, although we have a long way to go before the health of Indigenous Australians matches that of the population as a whole. In 1999–2000, the Commonwealth Government spent 8.5% of GDP on healthcare, ranking our health spending among the highest in the world. By contrast, many people living in our region are burdened by emerging epidemics, such as HIV/AIDS, diseases associated with economic and industrial development, and problems of communicable disease and nutritional deficiencies. For decades, many Australians have been working towards improving health in these developing countries by providing their knowledge and expertise. While the financial resources for healthcare are largely the responsibility of individual national governments, the international system plays an important role in assisting developing countries to improve their health standards. From our own experiences of working with AusAID and the World Health Organization on two projects to eradicate iodine-deficiency disorders in China and Tibet, we illustrate how health professionals can work with international aid agencies to deliver healthcare and make a difference to the lives of people in developing countries.

Mu Li PhD, MHSM · Creswell J Eastman AM, MD, FRACP

We can no longer ignore human-induced climate changes that are likely to affect our health There is wide agreement among climatologists internationally that human-induced climate change is now under way.1 Global climate change is one of various large-scale, unprecedented environmental perturbations occurring in today's world. These environmental changes reflect the rapid increase in human domination of the biosphere as human numbers increase and as economic activities intensify.2,3 This process has, apparently, now passed certain critical points. Indeed, one recent environmental analysis showed that humankind has been operating in ecological deficit since the 1970s: we now consume and deplete Earth's natural environmental capital faster than it is being replenished and restored.4 These changes — climate change, stratospheric ozone depletion, loss of biodiversity, worldwide land degradation, fresh water depletion, disruption of elemental nitrogen and sulfur cycles, and global dissemination of persistent organic pollutants — have enormous potential consequences for the sustainability of ecological systems, food production, economic activities and the health of human populations. This may have sounded farfetched to "linear optimists" a decade ago. With the passage of each year, and continued global environmental trends, it now seems increasingly plausible. This issue of the Journal, meanwhile, features an ensemble of articles highlighting the current health effects of environmental exposures in five key areas: air,5 food,6 soil,7 water8 and ultraviolet radiation.9 Last year the United Nations Intergovernmental Panel on Climate Change (IPCC), in its Third Assessment Report, documented a coherent pattern of recent changes in various physical and biological systems.1 This included glacier retreat, sea-ice diminution, earlier bird-nesting, earlier flowering, altered timing of insect migration, and so on. While one swallow does not make a summer, the IPCC pointed out that the overall pattern points to the incipient impact of global warming. Where and when, therefore, might we see effects on human health? The answer is complex. First, most health outcomes are multicausal, and inevitably various non-climate causal factors are also changing over time. Second, climate change affects local environments differently, according to characteristics of local geography. Further, the vulnerability of each human population varies as a function of locality, level of material resources, technological assets and type of governance. For example, the small Pacific Island states are likely to feel the effect of climate-induced sea-level rise in the next 20–50 years. The resulting impairment of agriculture and freshwater resources is a particular concern, along with the health consequences of population displacement. Several recent reports have suggested that we may now be seeing some early impacts of climate change on infectious diseases. For example, tickborne (viral) encephalitis in Sweden appears to have increased in response to a succession of warmer winters over the past two decades,10 and there is some, though still inconclusive, evidence of malaria ascending to higher altitudes in the eastern African highlands in association with local warming.11 Meanwhile, the intensification of the El Niño Southern Oscillation (ENSO) over the past quarter-century, a likely consequence of global climate change, has been accompanied by a strengthening interannual association of the ENSO index with rates of diarrhoeal disease in Bangladesh.12 Of course, the health prospects are not all bad. Some impacts would be beneficial. For example, milder winters would reduce the seasonal winter-time mortality peak in temperate countries, and a further increase in temperatures in currently hot regions might impair mosquito survival. Overall, however, scientists have consistently predicted that most effects of climate change on health would be adverse.13 The impacts mostly entail changes in the frequency or severity of familiar health risks — such as the effects of floods, storms and fires; the mortality toll of heatwaves; the range and seasonality of infectious diseases; changes in local agro-ecosystem productivity and its nutritional consequences; the impact on health of changes in fresh water supplies; and the many repercussions of economic dislocation and population displacement. Studies in Australia are beginning to give us a better information base for estimating the impact of changes in climatic means and variability. For example, the dependence of Ross River virus disease on climate variation and its viral repercussions is becoming clearer.14,15 Various other studies have been reported on the climatic influences on Murray Valley encephalitis and on mortality from thermal stress.16 Hall et al (page 614) describe the relationship between temperature and the occurrence of food-poisoning.6 This year, the Federal Government funded its first formal assessment of the effects of climate change on health in Australia over the coming decades (soon to be published). Meanwhile, even as average global surface temperatures gradually rise, it is likely that we will face an increase in climatic variability, including extreme weather events.1 Indeed, many scientists now consider that human health and safety are more endangered by an impending increase in extreme and anomalous weather events than by changed average climatic conditions.17 The human species, because of its social organisation and cultural practices, is better buffered against environmental stressors than many other plant and animal species. Hence, Homo sapiens is likely to be affected less soon and less sensitively than most other species. Not surprisingly, therefore, there is little empirical evidence to date that climate change is already affecting human health. However, invoking the precautionary principle, we can recognise that adverse impacts are both likely and, in many cases, potentially serious. By thinking more ecologically about the large-scale influences on population health and disease, we could apply a more anticipatory approach.3 Society's ultimate objective should not be to generate wealth and increase consumption for its own sake, but to maximise the wellbeing, health and survival of its people. Indeed, the growing recognition of the links between ecological infrastructure, social conditions and health is beginning to highlight population health as a criterion of "sustainable development".18 We and our governments need to move beyond the narrow, short-term vision of the UN World Summit on Sustainable Development, held in Johannesburg in August 2002. The outcome of the Summit was constrained by preoccupations with achieving continuing economic growth, the needs and responsibilities of transnational corporations, and the alleviation of poverty — primarily by the creation, not redistribution, of wealth. Much of the debate was distorted by recriminations between rich and poor countries, and by self-interested US power-play tactics to minimise various international collaborative commitments. There was relatively little recognition of the damage that humankind is now doing to Earth's life-support systems, and its consequences for humans. Considerations of health in relation to ecological sustainability received little attention. One positive, late-breaking development at Johannesburg was the commitment made by Russia and China to comply with the international Kyoto Protocol on greenhouse gas emissions. Indeed, that initiative left Australia looking even more aberrant on this great modern environmental issue than it did before the Summit. The topic of climate change and health will evolve rapidly during this decade. Researchers are increasingly coming to grips with this and related issues. The point of such research is to enrich the information base for farsighted decision-making. As Rene Dubos, the eminent microbiologist, might have said if he were alive today, "Think future, act now."

Anthony J McMichael MB BS PhD · Rosalie E Woodruff BA MPH

We need imaginative city planning which redirects spending on roads to public transport, footpaths and cycleways The classic divisions of environmental health by the vectors food, air and water lend themselves to studies of the causes of disease, but the best approach when looking for environmental health interventions is to focus on the organised areas of human activity that have the greatest impact on the environment — housing, employment, manufacturing and transport. Of all these, transport provides perhaps the greatest potential for health gain, at least in First World countries. The choices we make in transport bear directly on the health of the population. During 2001, an average of 159 597 vehicles crossed the Sydney Harbour Bridge daily in both directions. This compares with an approximate average of 10 900 vehicles crossing the Bridge daily when it was opened in 1932 (Mr Barry Armstrong, Traffic Data Analyst, Traffic Information Group, Traffic and Transport Directorate, NSW Roads and Traffic Authority, August 2002, personal communication). The most familiar risk to health in our car-dominant transport system is road-accident death and injury. In 1999, road accidents resulted in 509 deaths and 12 000 injuries in New Zealand,1 and, in Australia, 1759 deaths1 and an estimated 30 000 injuries requiring hospital treatment.2 About a third of the deaths occurred among children and adults under 25 years of age.1 In fact, these figures reflect recent declines in road accident fatalities in Australia and New Zealand, and one of the public health success stories of the second half of the 20th century. In both countries, fatality rates more than halved between 1970 and 2000. Road accidents are frequently attributed to speeding, carelessness and risk-taking, but changes in the behaviour of road users do not explain the drop in the road toll: more important factors have been better vehicle design (including seat belts), safer roads and fewer vulnerable road users (such as pedestrians, bicyclists and motorcyclists).3 By the standards of most OECD countries, however, our rates of road-accident deaths and injuries are still high. In 1999, road deaths per 100 000 were 13.3 (NZ) and 9.3 (Australia), compared with 9.7 (Canada), 6.6 (Sweden) and 6.0 (Britain).1 Furthermore, current patterns of industrialisation worldwide suggest that road accidents will become more prominent as a cause of death and injury. Already, more people are killed on the roads each year worldwide than die from malaria (2.3% v 1.9% of the global population).4 By 2020 road accidents are predicted to rank third among the causes of global disability-adjusted life-years lost, after cardiovascular disease and depression, and ahead of cancer. Road accidents are nevertheless just the tip of the transport and health iceberg. The effects of vehicle emissions on public health have been considerably under-rated. New data on the relation between exposure to fine airborne particles and mortality suggest that the burden of disease attributable to traffic pollution may be at least as great as that caused by road accidents. In Europe, the number of premature deaths among adults caused by vehicle emissions was estimated to be more than twice the number of deaths from road accidents, albeit with rather fewer years of life lost.5 Using the same approach, in New Zealand we have estimated that about 400 deaths per year can be attributed to traffic pollution.6 By comparison, about 960 deaths per year in Sydney in 1989–1993 have been attributed to exposure to particulate pollution from all sources.7 Not counted in these analyses are the effects of global air pollution as a result of vehicles, roadbuilding and fuel production. The transport sector is a major contributor to climate change. Transport emissions — already responsible for 28% of total greenhouse emissions in New Zealand8 and 16% in Australia9 — are increasing more rapidly in both countries than those from any other sector (see also the article by McMichael and Woodruff [page 590] on climate change and health10). Perhaps the most serious public health implication of our car-dependent societies is the unprecedented level of sedentariness that this lifestyle encourages. In cities, where the majority of Australians and New Zealanders now live, the proportion of trips made by walking, cycling or using public transport has plummeted. In the past 10 years, the proportion of New Zealanders cycling to school and work has fallen by more than 20%.11 In New Zealand and Australian cities, fewer than 5% of workers commute by bicycle, compared with 15%–20% in European cities.12 Fifty years ago, in New Zealand, there were 13 cars per 100 people; now, in both New Zealand and Australia, there are close to two cars for every three people. Some of the consequences of declining physical activity, such as increasing bodyweight and cardiovascular disease risk, are well known. Others, such as the dominating influence of trends in physical activity on the diabetes epidemic, are just becoming apparent.13 The evidence that lack of physical activity is strongly linked with certain cancers (colon and breast cancer, in particular) suggests that motor cars should be included in any up-to-date list of cancer-causing agents.14 A recent assessment of risk factors in Victoria suggested that lack of physical activity was outranked only by tobacco as a cause of ill-health.15 The Mount Victoria Tunnel connects the eastern suburbs of Wellington, NZ, with the city centre. When it was built in 1934, it was used each day by about 4000 vehicles and 2000 pedestrians. In 2001 there were about 34 000 (Health and safety aspects of the Mt Victoria Tunnel. 5th year medical student project. Wellington: Department of Public Health, Wellington School of Medicine and Health Sciences, 2001). Current transport patterns in Australia and New Zealand are firmly entrenched. For almost every aspect of daily life — recreation, socialising, employment — we depend on using a private motor vehicle. As a result it is difficult to avoid trade-offs that make sense at the individual level, but in the broad scheme of things only make the problem worse. We have all heard self-justifying comments such as: "If everyone else goes shopping in a four-wheel-drive then I feel much safer in one too", or "I need to drive the kids to school because the roads are too busy for them to walk". How can we change this? There are plenty of options that would result in benefit to the environment, the economy and human health. Examples include more fuel-efficient vehicles, and a better public transport system. Governments need to promote active transport strategies, such as supervised walking groups of schoolchildren ("walking school buses"), and workplace incentives to reduce car travel, such as public transport vouchers instead of company cars, and changing rooms and showers for cyclists. But major gains will require serious attention to the underlying structural factors that have produced our current high level of car-dependence12 and made walking and cycling more difficult and hazardous. These include removing economic subsidies that hide the true costs of roads and parking facilities, and limiting the urban sprawl that, to a large extent, dictates the use of cars. We need to think more imaginatively about how people can be helped to live close to the facilities they value. This means challenging many of the assumptions on which car-dependent city planning is based (such as the need for segregated land use and low-density housing). To achieve these goals there must be substantial redirection of transport spending from roads to other means of getting around, including public transport, footpaths and cycleways. Examples of positive changes that are now occurring include a less car-dominated National Transport Strategy in New Zealand, and initiatives such as New South Wales/Sydney Action for Transport 2010. We recognise the extreme difficulty of making these changes — there are many powerful reasons why society is car-dependent, including perceived comfort, convenience and security. But the negative health aspects of our present transport system have been under-rated. As Peter Newman, Professor of City Policy at Murdoch University, has pointed out,12 the changes that have to be made require a critical change in mindset, from the privatised world of the motor car and the remote, car-dependent suburb, to the public realm of common spaces, community interests and a global environment that we all share, and on which our public health depends.

Alistair Woodward PhD · Simon Hales PhD · Sarah E Hill MB ChB

While excessive exposure to ultraviolet radiation (UVR) is a significant cause of disease burden in Australia and the Western Pacific region, there are well documented beneficial as well as adverse effects of UVR exposure. Ambient UVR levels do not translate directly to personal UVR dose and thus to biological effect — each person's sun-exposure behaviour and pigmentation also play a role. Exposure in childhood may be more important than exposure in adulthood for both beneficial and adverse effects. Stratospheric ozone depletion increases ambient UVR in the UVB wavelength, possibly the most important wavelength for both beneficial and deleterious health effects. There is ongoing research examining the effects of UVR exposure on immune function, including an examination of the possible role of lack of UVR exposure in the aetiology of multiple sclerosis and type 1 diabetes mellitus.

Robyn M Lucas MB, ChB, MPH · Anne-Louise Ponsonby MB BS, PhD, FAFPHM