27 Oct 2014

Chemical level 'too high' in repellents

12:40 pm on 27 October 2014

Levels of the neuro-toxic substance DEET in insect repellents is too high, according to a Southland pharmacist.

George Batchelor said insect repellents containing 80 percent of the compound as the active ingredient are currently available in this country, despite the US Centers for Disease Control and Prevention (CDC) recommending just 30-50 percent as the highest level necessary for protection.

The origins of the insect repellent compound DEET origins go back to World War II.

The origins of the insect repellent compound DEET origins go back to World War II. Photo: AFP / USDA

In its Yellow Book on travelers' health, the CDC said studies suggested concentrations of DEET above about 50 percent did not offer a marked increase in protection time against mosquitoes.

It said DEET efficacy against mosquitos, ticks and other insects tends to plateau at a concentration of approximately 50 percent.

The World Health Organisation recommendation is a maximum of 40 percent.

Developed by the US Army in 1946 for soldiers involved in jungle warfare, the compound was found to have toxic effects in mammals in a 2009 study published in BioMed Central Biology, acting like nerve-paralysing gases used in war.

The Te Anau-based pharmacist said there should be a review of levels of the compound in products sold here, as there had been in some other countries.

In Canada, DEET levels for products used on adults are capped at 30 percent for adults and 10 percent for children, he said.

"When there are products available with up to 80 percent Deet in them, people often assume they should buy the highest percentage for better protection," said Mr Batchelor.

He said products containing the active ingredient Picaridin were becoming a popular alternative.

Get the new RNZ app

for ad-free news and current affairs