Rural women exposed to DDT - sprayed to reduce malaria - are likely to give birth to boys with urogenital birth defects (UGBD), say researchers.
The research led by the University of Pretoria in South Africa showed that women who stayed at home in sprayed villages, rather than being a student or working, had 41 per cent more baby boys with UGBDs, such as missing testicles or problems with their urethra or penis.
The authors suggest this is because they spent more time in homes where domestic DDT-based sprays are still commonly used to kill the mosquitos that cause malaria, even in areas where organised mass spraying no longer takes place.
"If women are exposed to DDT, either through their diet or through the environment they live in, this can cause the chemical to build up in their body," said lead author Professor Riana Bornman from the University's Department of Urology.
"DDT can cross the placenta and be present in breast milk and studies have shown that the residual concentration in the baby's umbilical cord are very similar to those in maternal blood.
"It has been estimated that if DDT exposure were to cease completely, it would still take ten to 20 years for an individual who had been exposed to the chemical to be clear of it.
"Our study was carried out on boys born between 2004 and 2006, five to nine years after official records showed that their mothers had been exposed to spraying.
"Although most countries have now banned the use of DDT, certain endemic malarial areas still use indoor residual spraying with DDT to decrease the incidence and spread of the disease, which is caused by mosquitoes," Bornman added.
The research team suggests that educating people living in the DDT-sprayed communities about ways of protecting themselves from undue DDT exposure needs to be carried out as a matter of extreme urgency.
"We are now carrying out further research to find out how indoor spraying using DDT-based products affects humans and how this risk can be reduced," said Bornman.
The study appears online in UK-based urology journal BJUI.