DENVER – Pregnant women should avoid pumping their own gasoline or painting the nursery to get it ready for the baby, among other activities, based on the results from a study at the Medical College of Wisconsin in Milwaukee.
The advice comes from Dr. Gail McCarver, a professor of pharmacology and toxicology there and the lead author on a study that found that exposure to ethylbenzene and trichloroethylene during pregnancy is associated with an increased risk of congenital heart disease (CHD).
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A study has shown a fourfold increase in risk for congenital heart disease among white infants who had fetal exposure to ethylbenzene, an organic compound found in gasoline vapors, vehicle exhaust, tobacco smoke, varnish, insecticides, and some paints.
Sources of ethylbenzene, a volatile organic compound, include gasoline vapors, vehicle exhaust, tobacco smoke, varnish, adhesives, inks, insecticides, and some paints and cleaning agents.
It was two metabolites of trichloroethylene – trichloroacetic (TCA) and dichloroacetic (DCA) acids – that the researchers linked to congenital heart disease.
Trichloroethylene is found in degreasing agents, adhesives, typewriter correction fluid, dry cleaning solvents, rug cleaners, and paint and varnish removers, among other sources.
The findings, which were reported at the annual meeting of the Pediatric Academic Societies, come from meconium analysis of 135 infants with CHD and 432 control infants without CHD. Fetal exposure to ethylbenzene and the metabolites were significantly more common among infants with CHD.
"What we saw was about a fourfold increase in CHD risk among [white] infants who had fetal exposure to ethylbenzene documented in meconium" after adjustment for race and CHD family history. "We could not document the same observation in African Americans," Dr. McCarver said.
It’s a novel finding. Ethylbenzene has not been associated with CHD until now.
The presence of the trichloroethylene metabolites was associated with a twofold increase in CHD risk in white infants and an eightfold increase in black infants.
Regarding the racial differences, "I don’t think it’s implausible that different racial groups could have different risk factors. There are racial differences in the enzymes that handle these kinds of compounds," said Dr. McCarver, who is also codirector of the birth defects research center at the Medical College of Wisconsin.
The results mean that pregnant women should avoid exposure as much as possible. "What I would tell [a pregnant woman] is, don’t pump your own gasoline; don’t smoke; don’t use cleaners if you don’t have to, [especially] cleaners that have warning labels that say use a respirator," she said.
Pregnancy isn’t a good time to paint the nursery or refinish the floors, either. "Young women are doing these kinds of things even early in pregnancy" when CHD develops, Dr. McCarver said.
In general, there are four to seven CHD cases per 1,000 live births. Previously established risk factors include smoking or heavy drinking during pregnancy, family history, and white race. Infants with diabetic mothers or chromosomal abnormalities – two additional risk factors – were excluded from the study.
When the compounds were included in the statistical analysis, "maternal obesity, smoking, illicit drugs, alcohol intake, vitamin use, other solvent exposures, and the genetic variants" dropped out as significant risk factors, the researchers said.
Because smoking in particular dropped out, Dr. McCarver and her colleagues speculated that it’s the ethylbenzene in smoke that’s responsible for prior reports linking CHD and smoking.
"If you were to say to me, ‘Which is worse, ethylbenzene or smoking?’ I’d say ethylbenzene," Dr. McCarver said.
Dr. McCarver said she had no relevant financial disclosures. The study was funded by the National Institute of Environmental Health Sciences.