Sting in the tail

Pregnant women are warned against using insect repellents.

15:26 05 August 2009

New advice is warning parents of young children and mothers-to-be against using holiday insect repellents.

The alert has come amid recent research findings, which have linked the use of products containing DEET – found in most repellents – with causing damage to the nervous system.

Tropical strength insect sprays contain up to 50% of the chemical DEET (or N,N-diethyl-m-toluamide), including top brands Autan and Jungle Formula, as well as many own-brand products.

French scientists identified the health risks posed by the powerful chemical, after studies showed it to be a neurotoxin.

The damage caused by DEET to the nervous system could potentially lead to fits in children. Pregnant women have also been advised not to use products containing the substance, as they are likely to be more vulnerable to harm.

DEET-based repellents have long been heralded as the gold standard and so have been a popular choice for holidaymakers. The chemical can also be bought neat to apply to wristbands, mosquito nets and clothes for total protection from the tiny menacing vampires. It is estimated that 200 million people worldwide use them each year.

Researchers from the University of Angers, France, who conducted the study, found that DEET blocked the action of the enzyme acetylcholinesterase in cockroaches and rats. This enzyme is key to the health of the nervous system and disturbing its activity could potentially lead to fits.

A relationship between the chemical and seizures in children has been reported previously. However, this the first study to identify direct harm done to the nervous system, according to reports in the BMC Biology journal. Researcher Dr. Vincent Corbet insists that urgent studies are now needed to assess DEET's safety for people.

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Until then, he recommends that children aged under six and pregnant women stay away from any products containing DEET, while adults should avoid using formulas containing more than 50% and should not apply repellents more than three times a day.

"I am not saying that DEET in normal use kills people but to be very careful as to the concentration, time of application and the target people," Dr. Corbet said.

Currently in Britain, some sprays state that they are not recommended for use by children under six-years-old, but others say they can be used on babies from the age of six months.