PCE-Contaminated Drinking Water Increases Risk of Stillbirth
Residents of Massachusetts and Rhode Island were exposed to the solvent PCE (tetrachloroethylene) in drinking water from 1968 through the early 1990s, after it was used to apply a vinyl liner to hundreds of miles of new drinking water mains. The Environmental Protection Agency discovered the source of the contamination in 1980 and ordered the water suppliers to flush the pipes repeatedly until PCE levels dropped below 40 parts per billion—the EPA’s established threshold at the time, eight times higher than the current threshold.
Now, a new study led by School of Public Health researchers finds that pregnant women who drank the PCE-contaminated water were up to twice as likely to have a stillbirth.
The study, published in Environmental Health, found women with any PCE exposure had a 1.7-fold increased odds of stillbirth due to placental abruption or placental insufficiency, and those with the highest level of exposure had a 1.9-fold increased odds.
“We were surprised to find an increased risk for low exposure levels because we have not seen that for other health effects,” says lead author Ann Aschengrau, professor of epidemiology. “We need to ensure that government regulations for drinking water contaminants take into account vulnerable populations such as pregnant women. We must ensure that our drinking water supplies are safe for all to consume.”
PCE is a known neurotoxin and “probable carcinogen,” according to the EPA, and previous studies, including several led by Aschengrau, have found a range of health consequences from this period of drinking water contamination, from birth defects to neuropsychological issues. Two smaller Massachusetts studies in Woburn and Cape Cod have also suggested an association with a moderate increase in the risk of stillbirth.
For the new study, the researchers looked at 296 stillbirths between 1968 and 1995 among women who lived in 28 Massachusetts and Rhode Island cities and towns with some affected water mains, and a control group of 783 live-born infants who were delivered in the same time period and geographic area. The researchers limited stillbirth cases to those attributed to placental abruption and/or placental insufficiency, which they had found to have the strongest association with PCE-contaminated water in their previous study. They then gathered data on other variables from vital records and from questionnaires answered by the women who had had stillbirths and live births. A woman’s degree of PCE exposure was estimated using a leaching and transport model integrated into water system software.
The researchers found pregnant women with any PCE exposure had a 1.7-fold increase in the odds of placenta-related stillbirth compared to unexposed mothers after adjusting for other variables. The adjusted odds ratio increased as a woman’s exposure level increased, with a 1.5-fold increased risk for the least-exposed women, a 1.7-fold increased risk for moderate exposure, and a 1.9-fold increase for the highest level of exposure (the 90th percentile).
The researchers also found a similar pattern when they divided the PCE-exposed women into only two groups: those whose exposure was estimated at above or below 40 parts per billion, which was the threshold that the EPA originally considered high enough to warrant taking action. The women with exposures below the threshold had a 1.5-fold increased odds of stillbirth, while those above the threshold had a 2.6-fold increased odds compared to unexposed women.
Although PCE contamination from vinyl-lined pipes is no longer a problem in Massachusetts and Rhode Island, the authors wrote that the solvent continues to be a common contaminant in drinking water throughout the United States because of improperly disposed waste from PCE use in textile processing, metal degreasing, and dry cleaning. “The latest drinking water assessment from the US Geological Survey detected PCE in 7 percent of surface water samples and 24 percent of groundwater samples,” the authors wrote.
The study was co-authored by: Lisa G. Gallagher, former assistant professor of epidemiology; Michael Winter, associate director of statistical programming at the Biostatistics & Epidemiology Data Analytics Center; environmental health doctoral candidate Lindsey J. Butler; M. Patricia Fabian, research assistant professor of environmental health; and Veronica M. Vieira, adjunct associate professor of environmental health.