Challenges to Demonstrating Chronic Health Effects Associated with PFAS
Demonstrating causal links between chemicals and chronic health conditions is challenging; some capitalize on the inherent complexities to confuse conclusions.
2023 is an action-packed year for PFAS in the US. Citing new data on human health effects of PFAS, the EPA is in the process of finalizing tough new controls of PFAS levels in drinking water. Meanwhile, one of the country’s biggest class action lawsuits (currently > 4000 plaintiffs) is scheduled to kick off in June: City of Stuart vs 3M etal. Some cost estimates associated with 3M’s PFAS litigation alone range past $30 billion.
Though certainly a major player, 3M isnt the only defendant in the PFAS litigation. Spokespeople for both 3M and Chemours have tried to influence the court of public opinion claiming the concerns surrounding the impact of “forever chemicals” on human health “lack a sound scientific basis” (3M) and are based on “bad science” (Chemours).
Science is a scaffold - a provisional framework built to support all the data we have at one time. As we learn more, the scaffold changes, becoming more robust to accommodate known data. Sometimes, it gets torn down and redesigned to accommodate a new finding. Science is active: expanding, failing, rebuilding, connecting. There is an expectation in science that, with good data, any conclusion can be questioned or challenged and, if data can be produced to justify it, adjusted.
That science is dynamic is not a fallibility. It is the essence of why it works so well.
Claiming that the science is fallible is a tactic often employed by industry to create doubt where, scientifically, little exists. This tactic is especially effective when it comes to evaluating chronic health risks, an effort that is incredibly complicated, especially when it comes to PFAS, given the global contamination of these many compounds. Here are a few specifics that complicate the study of chronic health effects associated with the persistent, globally-distributed, “forever chemicals”:
Because PFAS contamination is so widespread, it’s virtually impossible to identify uncontaminated humans to use as a control group. Ideally, any scientific evaluation has a control group, in this case, a group of humans that have not been exposed to PFAS. The Center for Disease Control and Prevention estimates that 97% of Americans have PFAS in their blood, making it virtually impossible to identify an unexposed control group to use when evaluating health effects.
There are many different PFAS in most humans, thus it’s nearly impossible to characterize the health effects of a single one. Similar to 1), widespread contamination complicates interpretation of health effects associated with a single PFAS compound…there’s always more than one. Recent studies have characterized up to twenty-six different PFAS compounds in drinking water. Over 65% of all the drinking water sampled evidenced some PFAS contamination, and researchers identified more than 25 different PFAS compounds. The CDC monitors only a subset of PFAS compounds and has indicated that at least three are present in the blood of the vast majority of Americans at levels > one part per billion.
PFAS health effects can be additive or can complicate other health conditions. Although there is evidence that certain PFAS have health effects in humans by themselves, the reality may be much more challenging to untangle. For example, a recent study investigated the link between PFOS and prostate cancer. Researchers found that risk between PFOS and prostate cancer is increased if the subject eats a high fat (aka American) diet. While the link between PFAS and prostate cancer is alarming, it becomes even more so when you consider the risk magnification that is likely relevant to many exposed Americans who eat an average American diet.
At exposure levels relevant to the American public, the effects of PFAS are not acute but chronic, complicating characterization of long-term, life changing health effects. Chronic health effects, including cancer, liver disease, and high cholesterol are inherently harder to study because there are so many potential uncontrolled variables. It is complex, scientifically, to observe a health effect that develops over time and that may have many potential sources or influencers. For example, a recent study indicates a link between elevated exposure to PFAS and increased weight gain. The study was based on data collected from several hundred people covering different genders, ages and diets and tried to address differences in the various lifestyles of participants. The conclusions are scientifically sound, but the data required to develop the correlation is extensive and complex and a causal relationship is not yet fully demonstrated. In one of the largest epidemiological studies ever conducted, scientists concluded there is a “probable link” between PFOA and 2 types of cancer, thyroid disease, ulcerative colitis, pregnancy-induced hypertension and high cholesterol. Despite the extensive data collected in this massive study, Dupont, the defendant in legal actions around the community hosting the study, continues to challenge claims.
It appears that PFAS will be in the headlines throughout 2023. Hopefully the public will be able to sort through the inevitable diversions and the intentional misdirection tactics to consider the science and the data relevant to protecting the health of our families and communities.
