Sydney: Researchers on the basis of a new study have revealed that pregnant women who are exposed to high levels of pesticide have fair chances of delivering babies who have lower IQs.

The study was concluded on the basis of three separate studies, two were conducted in New York City and a third in Salinas, a farming area in northern California.

The studies spanned nearly a decade, tracking levels of pesticide in expectant mothers and testing nearly 1,000 children up to age nine, a daily reported Thursday.

Researchers studied a family of pesticides known as organophosphates that are commonly used on fruit and vegetable crops. The findings were published in the journal Environmental Health Perspectives.

A total of 392 children were involved in the California study. 'Researchers found that every tenfold increase in measures of organophosphates detected during a mother's pregnancy corresponded to a 5.5 drop in overall IQ in the seven-year-olds,' the study said.

The differences held even after researchers accounted for factors such as education, family income and exposure to other environmental contaminants, it said.

Researchers at Mount Sinai, New York, measured 400 women and their children from 1998 onward. They found that 'exposure to organophosphates negatively impacted perceptual reasoning, a measure of non-verbal problem-solving skills' between the ages of six and nine, according to the newspaper.

The third study was carried out by researchers at New York's Columbia University who focused on the chlorpyrifos pesticide, which was widely used to kill cockroaches and termites until it was banned from residential use in 2001.

In the sample of 265 children born before the ban took effect, higher prenatal exposure was linked to lower intelligence scores and poorer memory.

Even though the studies were carried out independently of each other, the similarity in results raises concern; the newspaper said quoting the lead author of the California study, Maryse Bouchard.

'It is very unusual to see this much consistency across populations in studies, so that speaks to the significance of the findings,' she said.

Most of the modern-day exposure to such chemicals would likely be through eating food treated with the pesticides. Experts recommend washing produce with running water and rubbing it to remove residue.

(Agencies)