To the Editor: "Chop-chop" tobacco is illicit tobacco that has been grown and clandestinely distributed by farmers and wholesalers and sold on without government intervention or taxation. There is no quality control over this illicit substance, which may be adulterated or "bulked up". It is sold illegally "under the counter" by weight for rolled cigarettes by unscrupulous tobacconists and grocers. This type of tobacco, which has been roughly chopped up (hence "chop-chop"), is very cheap compared with legally produced manufactured cigarettes.

The prevalence of the use of chop-chop in the smoking community is unknown. However, the Australian Taxation Office (ATO) has a keen interest in the distribution of this substance, and estimates that many millions of dollars are lost in revenue from the illegal sale of chop-chop. Arrests and fines initiated by the ATO have so far occurred primarily in Queensland and Victoria.

Results of analysis of chop-chop vary from batch to batch, but samples have been shown to contain nicotine (Professor G Starmer, Department of Pharmacology, and Mr B Tattam, Mass Spectrometry Unit, Department of Pharmacy, University of Sydney, personal communication). It may also be fumigated with bleach and may be bulked up to add weight (M Rushton, ATO, personal communication). Although most people smoke it because it is cheap, many have misguided beliefs, for which there is no evidence, that it is "better" than other forms of tobacco.

A retrospective survey was carried out to assess the prevalence of and attitudes towards illicit tobacco smoking among patients attending the Smokers' Clinics of the Central Sydney Area Health Service (approved by the CSAHS Ethics Committee, June 2002). Patients were routinely asked the type of tobacco they smoked and their beliefs regarding this type of tobacco. The results are shown in the Box.

Many of the patients attending the Smokers' Clinics (dedicated exclusively to patients who smoke and have chronic obstructive pulmonary disease [COPD]) smoke this type of illegal tobacco. Several patients volunteered that smoking chop-chop precipitated an acute exacerbation of their COPD. Four patients have recently presented to a hospital emergency department for exacerbation of COPD after smoking chop-chop. Although smokers are loath to volunteer their use of this illegal tobacco, smokers and clinicians should be warned that smoking chop-chop does not constitute a positive health move, is not less harmful, and may be quite dangerous. Quitting smoking altogether is the best health move.