Children have lower IQs if their mothers have been exposed to pesticides during pregnancy, three US studies* have found. The studies, published in the peer-reviewed journal Environmental Health Perspectives, monitored pregnant women for exposure to organophosphate (OP) pesticides and tested their children’s IQs.
The studies varied in that they looked at women in rural and urban settings, different ethnic groups, and dietary and environmental exposure. Two of the studies tested the IQs of seven-year-olds, while one study tracked children to the age of nine. All found evidence of an association between OP exposure and negative impacts on mental development.
“These studies are very significant because they all reach similar conclusions,” says Jo Immig, co-ordinator of Australia’s National Toxics Network.
The studies showed that low doses of prenatal OP exposure might be harmful, Immig says. “This is extremely concerning because it is very difficult to control low-dose exposures in the environment when organophosphates are widely used around homes, workplaces and also in agriculture. These findings illustrate the need for a total overhaul of the pesticides regulatory system in Australia to ensure that dangerous pesticides are removed from use.”
Organophosphates are nerve poisons that were developed as pesticides and chemical weapons in Germany before and during World War II. They became widely used in agriculture from the 1950s.
Australia has about 25 registered OP pesticides (down from 40), of which about 15 are under review, says Dr Simon Cubit of the Australian Pesticides and Veterinary Medicines Authority. They are applied to crops including vegetables, fruit, grains, legumes, cotton, pastures and turf, and are also used domestically in products such as cockroach baits and termite treatments.
Dr Cubit says the long-term trend is for OPs to be replaced by newer chemicals.
“ They have a high inherent toxicity and our management prescriptions have to be tight and careful ”
However, because the studies concerning children’s IQs were epidemiological (data-based) rather than laboratory-based, they did not warrant a regulatory response, Dr Cubit says.
By: Simon Webster
First published: October 2011