Two new studies suggest that occupational exposure to certain chemicals may increase a person’s odds of having an infant with a birth defect.

Father were the focus of one report. Birth defects among babies were linked to father who held jobs  ranging from mathematicisns, physicians and computer scientists to artists, photographers, food service workers, landscapers and hairdressers were  

"Our study provides additional evidence of exposures or risk factors among men that can increase the risk of birth defects in their offspring," said lead researcher Tania Desrosiers, from the Center for Birth Defects Research and Prevention at the University of North Carolina, in Chapel Hill. "In general, most of the associations we observed between occupations and birth defects were modest."

For example, children of photographers and photo-processing workers were about three times as likely to have congenital glaucoma as offspring of men who worked in other occupations, Desrosiers said.

"Although this increased risk may sound alarming, primary congenital glaucoma in the general population is actually quite rare, with approximately one in 10,000 infants affected," she said.

The report was published online July 17 in the journal Occupational and Environmental Medicine.

Some jobs appeared to be linked to specific birth defects: artists (problems with the mouth, eyes and ears, gut, limbs, and heart); photographers and photo processors (cataracts, glaucoma, insufficient eye tissue); drivers (glaucoma and insufficient eye tissue); and landscapers and gardeners (gut abnormalities).

"We don't advise men to change jobs, but it may be prudent to avoid unnecessary exposure to chemicals and other potentially dangerous agents in the workplace," Desrosiers said. "One way to reduce exposure is to wear personal protective equipment."

What causes this association isn't clear. More research is needed to identify whether specific exposures, such as exposure to organic solvents or pesticides, for example, might account for the observed relationship between particular jobs and birth defects, she said.

How this might happen is unclear, said Dr. Michael Katz, interim medical director of the March of Dimes. "Is it the exposure of the father that might affect sperm?" he said. "Is it exposure to the mother from clothing brought into the house? Is it something they transmit to their partners?"

"I find it extremely hard to figure out why being a mathematician would have any sort of influence, because mostly what they do is think," he said.

These papers will evoke other, more comprehensive studies, Katz said.

In the second report, also published in Occupational and Environmental Medicine, researchers found exposure to organic solvents at work seem to be associated with several types of heart defects at birth.

"We are not ready to say solvents cause heart defects, but there seems to be some suggestion that occupational exposure to solvents is a risk factor for some heart defects," said researcher Suzanne Gilboa, an epidemiologist with the U.S. Centers for Disease Control and Prevention.

This is not a definitive finding, and needs to be validated in other studies, she added.

Exposure to these solvents could increase the risk of having a baby with a heart defect by 60 percent to 70 percent, Gilboa said. The absolute risk, however, is low.

Organic solvents are used for dissolving or dispersing things like fats, oils and waxes, and in chemical manufacturing. They are found in paints, varnishes, adhesives, degreasing/cleaning agents, dyes, polymers, plastic, synthetic textiles, printing inks and agricultural products, according to the report.

Most of these solvents are highly volatile and can be breathed in or absorbed through the skin or mouth.

While they studies uncovered an association between parents' occupations and birth defects, they did not prove a cause-and-effect relationship.

SOURCES: Tania Desrosiers, Ph.D., M.P.H., Center for Birth Defects Research and Prevention, University of North Carolina Gillings School of Global Public Health, Chapel Hill; Suzanne Gilboa, Ph.D., epidemiologist, U.S. Centers for Disease Control and Prevention, Atlanta; Michael Katz, M.D., interim medical director, March of Dimes; July 17, 2012, Occupational and Environmental Medicine, online