But, as Kim Sengupta discovers, at least 50 health authorities continue to recommend the use of malathion in some form.
More than a million bottles of shampoo containing the organophosphate malathion are sold by pharmacists every year.They are being used to control an head-lice infection sweeping through schools in Britain. Yet new research claims its repeated use can be highly dangerous, and may cause damage to the nervous system.
Organophosphates (OPs) were developed by the Nazis as a weapon and later used as agricultural pesticides. Over-exposure to the chemicals have been linked to potentially serious illness including nerve damage, birth defects, and cancer.
Tests carried out at the Government's Health and Safety Laboratories in Sheffield showed the amount of OP sabsorbed by anyone using malathion shampoo was five to ten times higher than safety limits. Dr Kerr Wilson, at the laboratory, said that if similar levels had been found on pesticide workers, "we would alert our colleagues in the health and safety executive to this finding, and they would take appropriate action".
Granada TV's World in Action programme, which is to broadcast the research findings on ITV tonight, discovered that out of 75 health authorities, 50 list malathion for use against head lice.
Dr Martin Regan, at Liverpool Health Authority, stated: "Our policy at the moment is to recommend malathion ... to kill the bugs". Dr John Maunder at East Norfolk Health Authority said: "Our current treatment is malathion lotions, and if that fails then Carabyl, but that would be on prescription only. And Dr Roger Buttery, at Cambridge Health Authority, said: "We have a three-year programme - we are currently recommending the three products that use malathion."
Other authorities supporting the use of malathion shampoos include Suffolk, North West Anglia, Bedfordshire, North and East Devon, Sheffield, Northamptonshire, and Buckinghamshire.
Dr Goran Jamal, at Glasgow University's Department of Neurology, who had researched OP poisoning, said that the shampoo should be used with extreme caution. He pointed out that although a single application of the delousing lotion was unlikely to cause damage to a child's health, repeated application, which can take place because of the risk of reinfection, could be dangerous.
He continued: "People forget that the reasons OPs make good pesticides is that they are extremely poisonous. Claims by manufacturers that we know everything about them and they are entirely safe are total nonsense."
Dr Vyvyan Howard, director of the Foetal and Infant Toxicopathology at Liverpool University, said the daily safety level of absorption were being exceeded by four or five times. He added: "The most worrying aspect of our findings is the problem of repeat applications of malathion shampoo because there is a delayed toxicity to nerve cells associated with OP compounds and that really is the thing that needs to be avoided, particularly with young children."Reuse content