Sir: The recent decision, based on "prudence" and the precautionary principle, to place the headlice treatment carbaryl on prescription-only sale is to be welcomed ("Cancer link leads to ban on sale of headlice remedies", 8 November). Carbaryl was first synthesised in 1953 and reports about its carcinogenic effects appeared in 1970. Other information about possible mutagenicity, reproductive, neurological and immunological effects of carbaryl has been available for at least a decade. It seems strange that the new policy had to be triggered by more evidence from the manufacturers about carcinogenicity tests in laboratories and not by our regulators acting on existing data and knowledge of data gaps.
What will now happen to those agricultural, horticultural and public- health workers who still use carbaryl on crops and for various pest-control purposes?
In the US data sheets on carbaryl do indicate the substance may cause mutations and may present reproductive hazards. Users there have some form of informed consent about which pesticides they choose to purchase. At the very least similar labels should be attached to the product in the UK for all its uses. This has not led to the cries of scaremongering referred to by your newspaper in the UK. If people are better informed about potential and known hazards, if they are told that the science is often unclear or contradictory, they are less likely to be "scared" and more likely to find out about hazards and accept the tentative advice of experts.
Centre for Occupational and
Environmental Health Policy
De Montfort University