State health officials say residents on public water in Merrimack and Bedford have been exposed to perfluorochemicals, or PFCs, at rates higher than the general population, but lower than in some other exposed communities.
Blood tests from more than 200 residents in the two towns found levels of the chemical known as PFOA were roughly double what's found in the general population.
The contamination is thought to have come from a nearby Saint-Gobain performance plastics plant.
The levels were lower than people who were exposed in Bennington, Vermont, and in Hoosick Falls, New York – two towns that are also near a Saint-Gobain facility.
Ben Chan is the state epidemiologist.
“The difference that we have seen I think is understandably going to raise concern amongst people that consumed the water. And yet, we don’t know what, if any, health impacts may come from that difference.”
Chan says a national health study on PFCs and human health is needed to better understand the risks.
Some studies have linked PFOA to several health problems, including certain types of cancer.