In Pennsylvania, 3.5 million people are served by private well systems, according to Penn State Extension. To better understand potential contamination of the groundwater feeding these systems, a team of researchers from Penn State conducted a novel three-year citizen science study of per- and poly-fluoroalkyl substances (PFAS) - often referred to as forever chemicals - in 167 private wells across Pennsylvania.
Their study, available online and scheduled for publication in the July issue of the Journal of Environmental Management, revealed that 18%, or 30 out of 167, of private wells sampled exceeded maximum contaminant levels for drinking water set by the U.S. Environmental Protection Agency. Overall, they reported, 65%, or 108 out of 167, of the private wells tested had detectable PFAS concentrations, with each of the 20 tested compounds detected at least once. Several of the compounds were detected in nearly half of the wells.
"My immediate reaction when I saw all the data combined was a little bit of relief, because none of the numbers were as high as I feared they could be," said team leader and senior author of the study Heather Preisendanz, professor of agricultural and biological engineering in the College of Agricultural Sciences. "We were happy that most of the numbers we saw were within the drinking water standards. Only 18% of the wells had levels that were higher than the federal standards, but they weren't thousands of times higher than the drinking water standards, as we have seen in other places. The levels that we saw were relatively low and are treatable with pretty simple technologies that people can use in their households."
However, Preisendanz pointed out that that these results may not be representative of PFAS levels in all private wells, and that concerned residents are encouraged to test their water.
The researchers reported that the highest concentrations of total measured PFAS were detected in private wells in the southeastern region of Pennsylvania. Many of the wells in which PFAS was not detected were in the central or western regions of the state.
The team found that wells near developed land, defined in the study as having "constructed materials and impervious surfaces," were more likely to contain PFAS, and for wells sampled multiple times, PFAS levels were found to vary significantly. Finally, the researchers found that the socioeconomic status of private well owners was associated with PFAS in wells - but not in the way one might expect.
The connection between socioeconomic status and PFAS in wells was counter intuitive, according to study first author Kelly Kosiarski, graduate student in the Department of Agricultural and Biological Engineering. Contrary to expectations, she noted, the socioeconomic analysis of well owners showed no clear correlation between poverty and PFAS levels - in fact, just the opposite.
"One might assume that people who live in lower income areas with higher levels of poverty or lower socioeconomic score would have elevated exposure to environmental contaminants like PFAS, due to factors such as proximity to industrial sites, but we didn't find that to be true in the PFAS study data," Kosiarski said. "Among all the socioeconomic factors we considered, poverty was the most consistently significant - exhibiting an inverse relationship with PFAS in private wells. This negative association suggests that wealthier areas may have higher PFAS concentrations."
Significantly, researchers also did not find any correlation between proximity of wells contaminated by PFAS and agricultural areas that received applications of sewage sludge or biosolids. The terms refer to solids separated from domestic sewage and refined into a material dense with nutrients that can be used as a fertilizer for crops.
"This study was originally conceived to answer the question of whether or not biosolids applications were putting people at higher risk of PFAS in their drinking water," Preisendanz said. "And so, the participants we selected early in the study were chosen due to their proximity to biosolids application sites."
Private well owners participating in the study were recruited through Penn State Extension's Master Well Owner Network, which currently comprises more than 900 volunteers who are formally trained by Penn State Extension regarding best practices for well management and water sampling and who, in turn, have educated more than 60,000 other private well owners on proper construction, testing and maintenance of private wells, springs and cisterns. Participants acted as community scientists, sampling their water prior to any in-home treatment.
