Insecticides used in head lice treatment linked to behavioural disorders in children

A team of French researchers have found that children with high levels of pyrethroid, an insecticide commonly found in head lice treatment, are around three times more likely to display abnormal behaviour.

Scientists analysed the urine samples of 287 pregnant women and their children's urine samples six years later, and found a link between pyrethroids and behavioural disorders in children. The Sydney Morning Herald reports that researchers identified an ingredient called permethrin, which is part of the pyrethroid family and found in many head lice and scabies treatments, is associated with a greater risk of aggressive and defiant behaviour in children. The study also found that higher levels of pyrethroid in the urine samples of mums-to-be was linked with an increased risk of 'internalising' behaviours in their six-year-old children, such as being anxious and socially withdrawn. Apart from head lice treatments, pyrethroids are found in products such as scabies creams, mosquito repellents and animal flea treatments. However, Dr David Goddard, a lecturer in occupational medicine, says there are some weaknesses in the research,

"A reasonable public health outcome based on this study would be that exposure to insecticides should not be greater than is required to control their intended pest target, but the study does not provide a firm enough basis to restrict use of pyrethroids."

Professor Ian Rae, a chemicals expert at the University of Melbourne, also questioned if the link between pyrethroids and behaviour was significant enough to cause concern,

"We are all exposed to them and live with traces in our tiny bodies of as many as several hundred substances produced by the chemical industry and used in domestic, industrial or agricultural settings. Were the pesticides to blame in this case? Who can tell? Even the researchers admit that there could be 'reverse causality', that is, that children with behavioural problems - such as hyperactivity -might be somehow more exposed to pesticides."

The newspaper reports that Australia's Therapeutic Goods Administration, the authority responsible for regulating medicines, have said they will review the new research to determine if any action is required. Join the conversation on Twitter @HerFamilydotie