PFAS levels in ground and air could be higher than expected, research suggests
Background levels of toxic PFAS “forever chemicals” in the ground and air may be much higher than previously thought, federal testing of spatially random soil samples from across New Hampshire suggests.
The analysis found high levels of PFAS in all 100 shallow soil samples, which were taken from undisturbed land not close to known polluters. The chemicals are thought to largely have gotten there through the air, and the study, along with recent EU research, suggests similar levels of soil and air contamination throughout the world.
The findings are “pretty disturbing” and raise fresh questions about contamination of food and water, said Mindi Messmer, a former New Hampshire state representative who advocates for stronger PFAS bans.
“However it got here, it’s there and it is widespread,” she added. “It’s the fault of decades of regulatory inaction.”
PFAS are a class of about 15,000 chemicals often used to make thousands of products resistant to water, stains and heat. The compounds are ubiquitous, and linked at low levels of exposure to cancer, thyroid disease, kidney dysfunction, birth defects, autoimmune disease and other serious health problems. They are called “forever chemicals” because of their longevity in the environment.
PFAS are thought to be contaminating drinking water for more than 200 million Americans. Multiple studies have found rain to contain high PFAS levels and the chemicals have been discovered in ice near the globe’s poles. Regulatory efforts to date have largely focused on addressing water, but researchers have increasingly turned their attention to soil and air contamination, which are linked to water pollution.
The US Geological Survey testing in New Hampshire found PFAS in all samples checked in up to 6in of depth, and largely at levels between .1 part per billion (ppb) and 15 ppb. No limits on PFAS in soil exist federally or in New Hampshire, but the levels are millions of times higher than the US Environmental Protection Agency advisory drinking water threshold for some common PFAS compounds.
Many of the contaminated sites would trigger remediation in Massachusetts, New Hampshire’s southern neighbor, which set limits for individual compounds in soil between .3 and 2 ppb.
More broadly, research led by Stockholm University found global soils are being “ubiquitously contaminated” by four PFAS compounds, and at levels that were often above Dutch limits proposed in 2018.
“In many areas inhabited by humans, the planetary boundary for PFAS has been exceeded based on the levels in rainwater, surface water and soil, with all of these media being widely contaminated,” the paper’s authors wrote.
The Netherlands revised its soil limits upwards after about 70% of building projects at the time were halted because soil remediation was required and builders protested the thresholds, the Stockholm paper noted.
The soil contamination sources are impossible to pinpoint. New Hampshire is home to several major industrial polluters, including the military and fabric producer Saint Gobain. Some of its farms also spread sewage sludge typically contaminated with even higher levels of PFAS as a fertilizer alternative, and the levels may be slightly higher near Saint Gobain, but the chemicals can also travel long distances through the atmosphere, meaning some compounds in New Hampshire’s soil could be from anywhere.
“It is well known that PFAS transport atmospherically and there is long range transport of the chemicals, so there might be some influence of local sources – but what proportion of PFAS we found is local is not known,” said Andrea Tokranov, a research hydrologist with the USGS and study co-author.
The climbing ambient PFAS levels worldwide are the result of the chemicals’ properties, widespread use for over 50 years, and lax regulation, advocates say. Until recent decades, the chemical industry claimed PFAS would be diluted to non-dangerous levels in oceans.
But the chemicals do not break down once they are in the ocean, and instead cycle through the world’s hydrosphere, moving among soil, ground waters, surface waters, oceans, sea spray, the atmosphere and rain. As more PFAS end up in the environment, background levels will continue to climb and exceed limits set by regulators.
“The cycling of [PFAS] in the world’s hydrosphere means that levels of [PFAS] in rainwater will be practically irreversible,” the Stockholm paper’s authors wrote.
Though it is unclear how much of a direct impact the levels found in New Hampshire has on drinking water, it, rain and soil are all part of the same system as rain percolating through soil recharges the groundwater, Tokranov noted.
“Soils are an underlooked category because there’s been a huge emphasis on water … but we have a lot more to learn about environmental levels of PFAS across the country,” she said.
The high background levels may also have an impact on the world’s food supply. Crops can take up PFAS from the soil, or the chemicals end up in beef when cattle eat contaminated food and drink contaminated water.
Though the end impacts on drinking water and food are not totally clear from the New Hampshire study, the direction the findings point is “disconcerting”, Messmer said.
“There is widespread contamination of PFAS chemicals because we’ve had decades of pollution from manufacturers and inaction from a regulatory perspective, and this is the result of that inaction – it’s not OK,” she said.