Blog by Tom Bruton
I recently attended a Society of Environmental Toxicology and Chemistry North America meeting focused entirely on per- and polyfluoroalkyl substances (PFAS). To a casual observer, it might have seemed like just another scientific conference. Powerpoint talks, coffee break, powerpoint talks, poster session, repeat. But below the surface, the meeting was the latest battlefield in an escalating fight over environmental liabilities that could have multibillion dollar consequences for chemical manufacturers.
PFAS are a large class of fluorinated organic chemicals that don’t break down in the environment. Some are known to be linked to cancer and other serious health harms, but many haven’t been studied. Industry prizes PFAS for their usefulness—the chemicals have been used for decades in firefighting foam, manufacturing, and consumer products like clothing and cosmetics. Because of their persistence and widespread use, scientists can now detect PFAS nearly everywhere on the planet and in nearly every person studied.
PFAS manufacturers have paid hundreds of millions of dollars in recent years in settlements for pollution near their production plants. The companies now face a slew of new lawsuits over drinking water contamination caused by firefighting foam. The firefighting foam sites are numerous, and the costs of providing clean drinking water and remediation will be steep. But liability for cleaning up these sites would become even more serious if PFAS are designated hazardous substances under the Superfund law. And Congress has been threatening to do just that.
Against this backdrop, researchers, regulators and risk assessors from around world came to the meeting to discuss the state of the science on PFAS. The most controversial discussion surrounded a proposal to revise the way that water guidelines are calculated for one notorious PFAS called PFOA. Michael Dourson, a toxicologist with strong industry ties, proposed using a small study in which terminal cancer patients were administered extreme doses of PFOA to revise estimates of the lifetime of the chemical in the human body. The very low drinking water limits that some states have proposed for PFOA are driven in large part by PFOA’s persistence in the human body. Lowering estimates of the chemical’s lifetime would result in higher limits, triggering fewer site cleanups and less liability for industry.
After Dourson’s talk, a long line of scientists politely but firmly raised objections to his proposal. Some pointed out that an unfortunate group of dying cancer patients dosed with very high levels of PFOA is not a reasonable population on which to base health guidelines for low environmental exposures. Others noted that PFOA’s persistence in the body is settled science, grounded in large scale studies performed in communities with contaminated water. Others called into question the ethics of the cancer study.
The discussions from the meeting will be summarized in a series of peer-reviewed journal articles. As Dourson was co-chair of the session in which he spoke, some worried that he would present his own conclusions as group consensus. By the close of the meeting that seemed less likely, but the summary paper will still need scrutiny. There is a lot riding on it.