Drinking water contaminations have affected water piped to more than 49 million Americans since 2004, according to an exhaustive study just completed by The New York Times. And while the government is aware of the violations, it has rarely fined or punished the violators.

PCE is a commonly used solvent and frequent contaminant of drinking water supplies. So, should you worry about it?

The answer is yes, according to a study published in the open access journal Environmental Health in September. The study tracked the infants of pregnant women exposed to the chemical inadvertently by PCE coating inside water piping used on Cape Cod between 1969 and 1983.

But the EWG study team discovered significant levels of exposure to four toxins, in reviewing EPA data. It found that dacthal, a herbicide, contaminated water served to 486,000 people in six states. In addition the study found significant exposures to aldrin, a neurotoxic form of dieldrin, and to soil fumigant 1,3-dichloropropene.

“High” exposure to byproducts of chlorination consisted of trihalomethanes measured at a level above 20 ig/L. Exposure at this high level increased the risk of these birth defects from 50 to 100 percent as compared with the “low” level below 5 ig/L.