Both self-reported exposure and urine samples supported the link between the chemicals and newborn malformations such as cleft palate and limb deformities, they report in the journal Epidemiology.

Specifically, urine breakdown products pointed to bleach-containing solvents and glycol ethers - a group of solvents common in paints, cleaning products and cosmetics - as potential culprits.

Concentrated fumes from both types of chemicals are toxic to humans, and glycol ethers in particular cause birth defects and developmental problems in animals.

A U.S. study published earlier this year also found a link between occupational exposure to solvents during pregnancy and several kinds of congenital heart defects.

Still, the new research is not ironclad proof the substances are to blame, and earlier research findings have been mixed. What's more, the overall risk is not huge, with less than three percent of the more than 3,000 pregnant women in the study giving birth to children with deformities.

Based on questionnaires filled out by the pregnant women, 45 percent of those whose babies had major malformations reported "regular" exposure to solvents at work. These women were typically nurses, chemists, cleaners, hairdressers or beauticians.

By contrast, of the women who had babies without birth defects, only 28 percent had been in regular contact with solvents at work.

The researchers, led by Sylvaine Cordier of the National Institute of Health and Medical Research in Rennes, France, said earlier studies had not looked at urine samples.

While that part of their research is limited by low detection rates and the study's size - one in five women had urine tests - it bolstered women's self-reported solvent exposure with objective evidence.

"These results identify work situations that require further investigation," Cordier and colleagues conclude.

SOURCE: bit.ly/SqkmkC Epidemiology, September 21, 2012.

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