With summer fast approaching and the spectre of evening barbecues dogged by mosquitoes, it is interesting to note that a recent US study confirms that personal repellents containing N,N-diethyl-3-methylbenzamide (DEET) are still the best available in that country. Fifteen volunteers tested 16 products three times each (a total of 720 tests) using the “arm-in-cage” technique. DEET-based products provided complete protection for 88.4 to 301.5 minutes, depending on their concentration. Citronella-based products protected for 2.8 minutes (0.5%) to 18.9 minutes (10%, combined with other botanical oils) and a 2% soybean oil product (marketed for children) protected for 94.6 minutes. Wrist bands impregnated with either DEET or citronella were completely ineffective. For those of you who swear by a popular bath oil, this failed the test after 9.6 minutes. Interestingly, a product containing eucalyptus oil came onto the US market just as the study finished. Testing on six subjects ended in a skin reaction in one and a mean complete protection time of 120 minutes in the other five.
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