Faulty Risk Assessment Has Real-Life Consequences

PFAS, the “forever chemicals,” provides a perfect example of how faulty risk assessment can lead to real-world consequences that destroy people’s lives. This happens when federal agencies do not consider relative risk in their analyses and are blinded to the real-world implications of their actions.

A recent article discusses how finding PFAS contamination on a farm in Maine has caused a nightmare scenario for a young couple who can no longer drink their water or sell the crops they produce. The soil of their organic farm and its water are contaminated by PFAS that were present in municipal sludge used to fertilize the farm years before the young couple purchased it. This nightmare scenario is occurring more and more across rural areas in America, threatening to ruin the lives of countless farmers and others dependent on the food they produce.


PFAS, the acronym for per- and polyfluoroalkyl substances, are a large group of approximately 4,700 chemicals that contain linked chains of carbon and fluorine. They are sometimes called “forever chemicals” because they take a long time to break down in the body and the environment.

As discussed in my previous article PFAS are being blamed for every health problem imaginable. Media reports have linked them to cancer, kidney malfunction, immune system suppression, lower birth weight, and many other health effects.  However, the scientific data does not support these claims.

In June 2022, the EPA lowered the levels it considers safe for two PFAS, perfluorooctanoic acid (PFOA) and perfluorooctane sulfonic acid (PFOS), in drinking water health advisories to levels that are so low that the vast majority of laboratories can’t detect them. The FDA has not determined a safe level for PFAS in food, such as milk and meat, so some states have set their own safe levels for PFAS based on the EPA’s risk assessment for safe levels in drinking water.  

Health Advisories

Health Advisories are guidance from the EPA as to safe levels of chemicals in drinking water. They are NOT regulations. They are not required to be subject to the necessary cost-benefit analysis for major regulations. However, as shown by those poor farmers in Maine, their impact can have severe economic consequences. In a manner reminiscent of the effects of the 2016 CDC Opioid Guidelines, states have increasingly adopted health advisories as enforceable levels and set standards for additional areas besides drinking water, such as food and soil.

The Subversion of Risk Assessment

The EPA uses risk assessment to set safe levels for chemicals in the air, water, and soil, including the health advisories for PFOA and PFOS. Risk assessment was designed to be a data-driven, scientific means to determine the relative risk of a chemical harming human health.

It is well established that lead adversely affects children's brains and central nervous systems. A risk assessment would examine all the relevant studies, determine at what level these effects were noted, and then add an extra margin of safety in setting a safe level. 

The problem with the risk assessment for PFOA and PFAS is that there is no evidence that these chemicals harm human health. According to the most extensive government documentation, the recent Department of Health and Human Services (DHHS) Toxicological Profile on Perfluoroalkyls,

“Although a large number of epidemiological studies have examined the potential of perfluoroalkyls to induce adverse health effects, most of the studies are cross-sectional in design and do not establish causality. The available epidemiological studies suggest associations between perfluoroalkyl exposure and several health outcomes; however, cause-and-effect relationships have not been established for these outcomes” [emphasis added]

Among the outcomes of concern were:

  • Pregnancy-induced hypertension
  • Increases in liver enzymes
  • Increases in cholesterol
  • Decreased antibody response to vaccines
  • Small decreases in birth weight

The EPA chose to base its risk assessment upon decreased antibody response to vaccines because it enabled them to calculate a very low safe level for PFOA and PFAS. But this was an outcome that, in their words, had not demonstrated a “cause-and-effect relationship.” Let’s consider the underlying study.

The Science of the PFOA and PFOS Health Advisory

EPA selected a study examining 656 births in the Faroe Islands from 1997-2000 with follow-up in 2008, correlating the long-term antibody response to immunizations with blood levels of PFAS in the children and mothers.

PFAS levels were measured in maternal blood at 32 weeks of pregnancy and age 5 for the children. The children received boosters for diphtheria and tetanus at age 5. [1] Antibodies against tetanus and diphtheria toxins were measured four weeks after their boosters and again at age 7.

Children with the highest levels of PFAS in their blood at ages 5 and 7 had significantly lower antibodies after vaccines for diphtheria and tetanus than children with lower levels of PFAS.  

EPA used a series of calculations to determine a health advisory “safe level” of 0.004 nanograms per liter (ng)/(L) for PFOA and 0.02 ng/L for PFOS. [2] These health advisory levels are 100 to 1000 times lower than the minimum reporting level - the lowest level the vast majority of laboratories in the U.S. can detect, four ng/L.

Although this study found that higher levels of PFOA and PFOS in the blood correlated with lower antibody responses to vaccines for diphtheria and tetanus, other studies have not seen this effect. Studies examining an antibody response to other vaccines, including mumps, measles, flu, and rubella, have not shown an association with PFOA or PFOS levels.

As we have all learned from COVID-19, antibody levels are highly individual and appear to be affected by genetics and other factors that are poorly understood. Using antibody levels in a small group of children as the basis for setting a national safe drinking water level seems problematic. Finally, if this PFOA exposure were more generalized to many antibodies, it would be expected that PFOA exposure would be associated with a higher number of colds and other diseases. However, this is not the case. According to the Department of Health and Human Services,

“No consistent associations were found between serum PFOA and disease resistance, as measured by episodes of the common cold, fever, or hospitalization for infectious disease.”

SCOTUS, West Virginia, and the EPA

The Supreme Court recently ruled in West Virginia vs. EPA that EPA did not have the statutory authority under the Clean Air Act to control greenhouse gas emissions, particularly because these emission controls have a widespread impact on the economy.  This ruling is now cited as the basis for challenging other EPA rules and guidance, including EPA’s health advisories. Chemours recently challenged the EPA health advisory for another PFAS, hexafluoropropylene oxide dimer acid, citing flawed science and the Supreme Court decision that the EPA had overstepped its statutory authority by issuing health advisories that are not mandated by the Safe Drinking Water Act but having a significant impact on the economy.

When the government sets guidance or regulations, it must be based on scientific data showing real effects. This was not done in the case of PFAS. Nor were the economic consequences considered in a risk-benefit analysis. I hope that this issue will cause EPA to review their risk assessment procedure and reform it so that this does not happen again.  

[1] The children had initially been vaccinated at three months of age.

[2] A nanogram is a billionth of a gram, and a nanogram per liter is equivalent to parts per trillion (ppt).

Sources: EPA Drinking Water Health Advisory: Perfluorooctanoic Acid (PFOA) CASRN 335-67-1

EPA Drinking Water Health Advisory: Perfluorooctane Sulfonic Acid (PFOS) CASRN 1763-23-1