Is Perfection the Enemy of the Good?

By Susan Goldhaber MPH — Sep 13, 2021
For regulatory science, from Covid-19 to environmental regulations, today’s mantra is to “follow the science.” If only we had more and better science, they exclaim, we would know the correct answers and better protect public health. But “more” and “better science” often result in the opposite effect – i.e., less protection of public health. By trying to do “perfect science,” we often get in the way of good results in the protection of public health.
Image by David Mark from Pixabay

What is PFOA?

As discussed previously, PFOA is one chemical in a larger group, polyfluoroalkyl substances (PFAS), characterized by containing linked chains of carbon and fluorine. These chemicals have been nicknamed “forever chemicals” because they persist in the body and environment.

PFOA first came to the public’s attention in 2001 after it was found in drinking water in Ohio and West Virginia in a DuPont facility used in the manufacture of Teflon. Next, even though PFOA was not actually in Teflon, came scary stories about the health effects of Teflon. PFOA is used in fire-fighting foams and several household products, such as stain- and water-repellant fabrics and cleaning products. 

PFOA have been found in groundwater and drinking water supplies across the country, primarily from its use in fire-fighting foams found at military bases and airports where fire-fighting training occurs.      

Government Action

EPA has been studying PFOA for over 20 years and has prepared several comprehensive health assessment documents on the chemical.  

  • In 2005 (16 years ago!), EPA issued its first Draft Human Health Risk Assessment of PFOA - a summary of all the relevant studies published on the health effects and exposure to the chemical. 
  • In 2009, EPA issued a preliminary drinking water health advisory [1] for PFOA of 0.4 ppb, (parts per billion)
  • In 2016, the drinking water health advisory level was further reduced to 0.07 ppb

However, EPA never issued a drinking water regulation for PFOA. A federal drinking water regulation is more than just a number used by water utilities to remove the chemical. States use it to clean up waste sites and other places of contamination. Without a federal drinking water regulation, States, including California, New Jersey, and New York, are forced to develop their own number or forego clean-up initiatives. 

Executive Inaction Leads to Legislative Reaction

Congress is fed up with the length of time it is taking EPA to set a drinking water standard for PFOA. On July 21, 2021, the House of Representatives passed the PFAS Action Act of 2021, which aims to crack down on PFAS contamination by requiring the EPA to take a series of actions, including requiring the listing of PFOA as hazardous substances. The Senate has not yet approved the bill, but the Biden Administration has indicated that the president is likely to sign the legislation if it reaches his desk.

More importantly, the Bill will force EPA to set a drinking water standard and requirements for clean-up of PFOA. The toxicity of PFOA is not the issue. PFOA is not a very toxic chemical. No effects have been noted in humans who have consumed water containing the chemical, and animal studies have shown some effects, but only at very high doses. Congress acted because PFOA has been found in sites all over the country, and they are hearing from their constituents that they want it out! 

The search for “perfect” science

To regulate a contaminant under the Safe Drinking Water Act, EPA must first set a non-enforceable health goal at a level “at which no known or anticipated health effects will occur.” Since EPA issued a Health Advisory for PFOA in 2009 and revised it in 2016, why didn’t it use these numbers as the basis for its health goal and drinking water regulation? A three-word answer, Scientific Advisory Panels

The EPA uses Scientific Advisory Panels to review scientific documents, such as those PFOA Human Health Risk Assessments, to form the basis for their Health Advisories. Most environmental laws do not require that the EPA use Scientific Advisory Panels; it is more a misguided belief that more science will result in better public health protection.  

Every time a document undergoes a review, the panel scientists request more information that the EPA feels obliged to provide. Risk assessment procedures have changed over the years. Determining safe levels in the early 2000s consisted of searching the available literature for the available studies on the chemical, determining the lowest level where a critical effect was noted, and dividing the value by an uncertainty factor. It was a relatively simple, straightforward, quickly completed procedure. 

As the 2000s progressed and computer power got cheaper and available to all, models entered the picture. Models require inputs, such as half-life information (see below), that require years of study and are still unsettled science today. In the search for perfect science, EPA is not content using health advisory values based on empiric research. Today, risk assessment has become a battle of the models.

“Old fashioned” risk assessment, while not as refined as models, was good enough to set safe levels that have been protecting public health for generations. Also, since safe levels, usually in the parts per billion  or trillion (ppt) levels, are intended to be benchmarked, not bright-line safe/unsafe values, the difference between levels derived by models and old-fashioned risk assessment is meaningless.   

What are the issues brought up by the Scientific Advisory Panels?

  • What is the half-life of PFOA?  Half-life data [2] is used in the newest models setting safe levels of PFOA. There has been a great deal of disagreement over its half-life. Current research indicates PFOA’s half-life values range between 0.5 and 1.5 years, rather than the currently used values of more than two years.

There is a certain irony in these results as it turns out that the “forever” chemicals may not actually last forever in the body. In addition, using a half-life in this range in the models could result in raising the existing safe levels calculated by various States and organizations

  • Does PFOA cause cancer? As with other chemicals, this too is an area of disagreement among scientists. Most of the studies in humans have not seen an increase in cancer from PFOA exposure. Two studies in rats showed an increase in liver tumors, but many scientists believe how PFOA causes the liver tumors are not relevant for humans. EPA has classified PFOA as having “suggestive evidence of carcinogenic potential” in humans. 
  • What is the critical effect of exposure to PFOA? The critical effect is a harmful effect seen at the lowest dose and is used to calculate a chemical's “safe” level. But differing critical effects can result in very different safe levels.  The critical effects used by various agencies for PFOA are: 
    • The developing fetus in mice exposed during pregnancy (EPA)
    • The immune system in animals and humans (European Food Safety Authority (EFSA))
    • Kidney cancer in humans (California)

Conclusions – A Bird in the hand, or two in the bush?

Today, the EPA is constantly falling down the rabbit hole of competing models and endless Science Advisory Panels and proclaiming, “I’m late, I’m late.” Is the public better served by imperfect knowledge now or perfect knowledge in some distant time. Congress does not think so, nor do I. The EPA should base safe levels on today’s best available science. Perhaps the EPA should set a time limit on the duration of Science Advisory Panel meetings – there is nothing like a deadline to focus your efforts.   

[1] Health advisories are “reasonable, health-based hazard concentrations above which action should be taken to reduce exposure to unregulated contaminants in drinking water.”

 [2] Half-length is the time required for a concentration of a substance to decrease to half its starting dose.     

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