Pregnant women with frequent exposure to solvents at work may be at a higher risk of having babies with birth defects, French researchers have found.
Urine samples supported the link between the chemicals and newborn malformations, such as cleft palate and limb defects, as reported in the journal Epidemiology.
Specifically, urine breakdown of products points to bleach-containing solvents and glycol ethers, a group of solvents common in paints, cleaning products and some cosmetics, as potential culprits.
Concentrated fumes from both types of chemicals become toxic to humans and glycol ethers, in particular, cause birth defects and developmental problems in animals.
The study published last month in the medical journal Epidemiology, found that pregnant women with high amounts of chemicals that contain bleach and glycol ethers in their urine, were more likely to give birth to a child with a cleft palate, cleft lip or other malformation.
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, new research is not definite proof that the substances are to blame and earlier research findings have been mixed. Even more, the overall risk is not huge, less than 3 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 report “regular” exposure to solvents at work. These women were typically nurses, chemists, cleaners or hairdressers. This is compared to the women who had babies without birth defects. Only 28 percent of these women 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. The researchers said they found a close-response relationship between occupational solvents and the rate of the birth defects, especially those including oral cleft, urinary tract malformations and male genital malformations.
The problem is that only 1 out of 5 women in the study gave urine samples and the rest filled out the questionnaires. The study was small in size and the findings call for further investigation.
The women who worked in semiconductor fabrication rooms from 1986 through the mid 1990s are potentially at risk for a higher incidence of birth defects from exposure to solvents.
The semiconductor industry used many toxic chemicals to manufacture parts used in building a computer, including hard drives, disk drives, circuit boards, video display adapters, and silicon chips; the basic parts necessary for computer devices. However, the toxic materials necessary to make the silicon chips include highly corrosive hydrochloric acid; metals such as arsenic, cadmium and lead; volatile solvents, such as methyl chloroform, toluene, benzene, acetone and trichloroethylene; and toxic gases such as arsine. Many of these chemicals are known to cause birth defects.
“This is a forgotten group of workers,” says Dr. Joseph LaDou, director of the International Center for Occupational Medicine at the University of California at San Francisco, who has studied the industry ever since large-scale semiconductor manufacturing began in the 1970s. In the U.S., nearly 300,000 people work in semiconductor plants; one fourth of them routinely perform tasks that put them in contact with the toxic chemicals used to produce the chips. Worldwide, the total number of semiconductor workers is approximately one million.
There is one step in particular that puts these women at an increased risk of inhaling solvents; creating the detailed patterns on the silicon layers. The technique is called photolithography. The clean room workers involved in this process work with the solvents for many hours each day, directly inhaling the toxic solvents.
In the mid 1990s, the industry began phasing out the use of glycol ethers. Still, many other chemicals linked to reproductive health problems, including xylene, trichloroethylene, phenols and acetone remain in use. In 1991, a Canadian study of pregnant women exposed to workplace solvents, much like those used in clean rooms, found that 13 out of 125 women had given birth to children with major congenital malformations, as compared to only 1 out of 125 in jobs involving no solvents.
The industry’s high rate of reproductive health problems is particularly alarming, researchers say, because semiconductor manufacturing has increasingly become women’s work.
Breathing in fumes is a serious concern for pregnant women. Oil-based paint contains solvents and requires turpentine or mineral spirits for cleanup. Over the years, some studies show exposure to solvents may increase the risk of having a miscarriage and heavy continued solvent exposure may raise the risk of birth defects and learning problems—so using oil-based paint or being around fumes during pregnancy is generally not recommended.
These toxic products should contain warning labels for pregnant women. For women who have to work at jobs where there are harmful solvents, there should be warnings posted.
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