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Dr. Dourson
This essay is about the “forever” chemical, per-fluoro-octano-ate, also known as PFOA, and similar chemicals. You have likely read about “forever” chemicals in the news or heard about these chemicals or saw the movie Dark Waters, where excess exposures to these chemicals were alleged to cause a number of significant health problems in people and farm animals. PFOA is one member of a group of chemicals that all have a fluorine atom attached to a carbon atom.
Such an attachment does not often occur in nature. The reason that this attachment is naturally infrequent and why we humans find it so very useful, is that this attachment is super strong. So strong that our bodies cannot break the attachment; so strong that foods cooked in a pan coated with a combination of PFOA-like chemicals do not stick; so strong that clothing treated with these chemicals are water resistant; so strong that food wrappings treated with these chemicals keep out bacteria, so strong that electrical and oil fires are more easily extinguished using fire fighting foams; and so strong that drugs made with this attachment allow our medicines to stay in our body longer to help us fight diseases. And the list of uses goes on and on. For example, the American Chemistry Council, lists these chemicals as:
“a large and diverse chemical family that makes possible products that power our lives – the cellphones, tablets and telecommunications we use every day; aircraft; alternative energy sources; and even medical equipment.”
So if these chemicals are so very useful, why is everyone so concerned about excess exposures? Well, it turns out that some of the chemicals with this carbon-fluorine attachment, PFOA in particular, and perhaps a few others, like to hang around quite a bit in our bodies, mainly because PFOA resembles something else that also hangs around---fat! Seriously? Yes, PFOA can also be referred to as a fluorinated fatty acid. Its natural counterpart is referred to as caprylic acid and it has a number of beneficial uses in addition to being a nutrient found in many foods (like coconuts!) that our bodies use for energy. So why does PFOA hang around? Because our kidneys think that this is a valuable chemical and so they pull most of the PFOA back out of our urine.1 Unfortunately, our bodies cannot use PFOA directly although it has been used for cancer treatment in at least one study.
Is the level of fluorinated chemicals in our bodies that are otherwise not medicine a concern? The quick answer is that this could be a problem if we have too much PFOA in our system when compared with the value set by a safety assessment. Since PFOA likes to hang around and not break down, we should not be surprised that governments all across the globe have done safety assessments for PFOA. Problem is these safety assessment values don’t agree, and they don’t agree in a very big way.
Risk scientists do not get concerned when disagreements are small. Small here means about 3 fold---yes, such differences are not small when talking about money, but this is biology and very imprecise. However, PFOA differences in these safety assessments are over 100,00 fold. Folks, I have been doing safety assessment for over 40 years, and NOTHING even comes close to the size of this disagreement. And the size of this disagreement, as you can imagine, leads to problems on whether to rely on one institution to provide the best analysis in setting safe levels or another.
You may know that the usual process of safety assessment for a chemical is for toxicologists to study the toxicity of a chemical in experimental animals, find the level that does not cause toxicity, and then toxicologists specializing in risk use safety factors and other adjustments to estimate a safe level in sensitive groups of humans (these scientists normally do not worry about estimating a safe dose for more resistant folks). PFOA is only modestly toxic in experimental animals, with amounts of about 30 micro-grams in a mouse causing effects (this is a little less than about one sugar grain from a pack of sugar).
Most governments agree in this range of toxicity. However, then these groups have to choose one study out of many, and then use safety factors and other adjustment to complete the safety assessment and arrive at a safe value. This is where large differences have occurred. For example, the Environmental Protection Agency’s (EPA) safety assessment of PFOA in drinking water is 0.004 ppt2 (part per trillion –one sugar granule in 1 liter of water is 50,000 ppt) and is much lower than others, for example Australian/New Zealand is at 560 ppt. EPA used a human study that other groups do not think is a good basis for a safety assessment. Although using a human study seems better than using animal studies, sometimes they are not. For example, many years ago society depended on a flawed human study linking vaccines to autism. This study was so badly done and presented so many issues that it was abandoned, but not before causing havoc in the medical community regarding public safety.
One would think the EPA and Australian/New Zealand would be communicating about this large difference in safety assessment values, and hopefully they are. But when I was “down under” last September for two weeks, the Australians were quite perplexed (a polite word), actually incensed, at the EPA safety assessment, and folks I spoke with did not indicate that any discussions with EPA were happening. It would seem such collaboration would not only be helpful but necessary.
The World Health Organization (WHO) also recently reviewed much of the same data as EPA, Australian, and New Zealand and concluded that the scientific uncertainties, readily demonstrated by the 100,000-fold difference, were too large to do a safety assessment. Instead, the WHO made a management decision of 100 ppt in drinking water for PFOA. An unfunded international collaboration appears to be heading in the same direction as the WHO. WHO’s guidance is followed by many countries.
Well, what to make of all this? We have drinking water health advisories of 0.004 ppt for EPA, 100 ppt for WHO and 560 ppt for Australian/New Zealand. Good scientists often make different safety assessments. This is well known and not unexpected, and, in general, differences in the range of 3-fold are of no concern as already mentioned. Differences of about 10-fold are likely to raise eyebrows (well at least among risk scientists). In these cases the usual reason for the differences is that one evaluation is older and where the underlying science has improved. In the case for PFOA, however, all of these evaluations are contemporary. Differences of 30 to 100- fold are cause for grave concern. The public’s health may not be protected when using the higher safety assessment, or a large amount of money may be spent needlessly when using the lower safety assessment. And a difference of over 100,000 fold you ask? Nothing short of a breakdown in one or more group’s critical thinking.
PFOA and PFOS were used early on to solve a problem in protecting human life. The problem? In 1967, a fire occurred aboard the USS Forrestal during combat operations. Firefighting foams used on the US ships at the time were made from proteins and were ineffective. As a result 134 sailors died and 161 were injured. PFOA/PFOS was later put into the foam with remarkably protective results.
Success in fighting such fires with PFOA/PFOS foam continues to this day. For example, an uncontrollable oil fire in 2019 at Deer Park, Texas released 200,000 pounds of chemicals per hour into the air for over 50 hours –over 10,000,000 pounds of contaminants– before fire- fighting foam with PFOA and PFOS were used to put the fire out in 13 hours. Many of these contaminants are associated with respiratory and heart diseases. So an obvious risk was avoided to folks living around this area with the use of the PFOA/PFOS foam that quickly put out an otherwise uncontrollable fire. What was the trade-off? PFOA/PFOS put out a fire in 13 hours and contaminated the environment to a low level that might not be harmful, versus adding more than 10 million pounds of air emissions at concentrations that are known to cause toxicity.
Yes, PFOA/PFOS foams are very good at putting out fires and have been used extensively in the past. Unfortunately, at present, there is no alternative to fluorinated fire-fighting foams that maintains the superior performance characteristics as the current versions. You don’t have to take my word for it. Here are three expert statements:
But the lack of good fire-fighting foams is not the only problem, and even though the lack of these foams is likely to result in more deaths, it may not even be the biggest problem. The U.S. District Court for the Southern District of Ohio ordered class status for “individuals subject to the laws of Ohio, who have 0.05 parts per trillion (ppt) of PFOA (C-8) and at least 0.05 ppt of any other PFAS in their blood serum.” As previously mentioned, one sugar granule from a package of sugar is about 50,000 ppt in a liter of water. So the court’s judgment of 0.05 ppt is 1,000,000 times smaller than one sugar granule. So does this judgment means that Ohio residents with small amounts of “forever chemicals” in their blood can be sued for donating blood to save someone’s life? Hmm…
And, unfortunately, the litigation does not stop there. The city of Mansfield, Ohio is suing a number of organizations over low levels of PFOA and related chemicals in the surface water, groundwater and soil of the Mansfield Lahm Regional Airport. In Maine, organic farmers are being sued for levels of PFOA and related chemicals in their soils. Underwear manufacturers are being sued for PFOA and related chemicals in their products. The number of lawsuits is voluminous and in many areas. Where will this all end? I’m afraid it’s not going to because we have such widespread, low-level contamination. The question we need to consider before spending billions of dollars on litigation is whether this low level contamination is a health risk, and for this we need to get the correct safe dose, as mentioned above.
So what can we all do? Write, call or email your congressman/woman and/or representative, both national and local, and insist that the US EPA (contact: Mr. Pigott Bruno: pigott.bruno@epa.gov; 202-564-5700) work with international organizations, such as New Zealand, Australia, Canada, and the European Food Safety Authority, or with an existing international collaboration, to get the right safe dose.
Your help is not only welcomed, it is needed. Otherwise, litigation on this chemical is likely to go on “forever.”
1 These chemicals are referred to as “forever” chemicals because some estimates have them staying in our bodies for well over 4 years, although a recent international collaboration shows that these estimates may be much shorter.
2 This value is EPA's Health Advisory, akin to it Maximum Contaminant Level Goal (MCLG). Recently EPA proposed a Maximum Contaminant Level (MCL) of 4 ppt.
Dr. Michael L. Dourson has a PhD in Toxicology from the University of Cincinnati, College of Medicine, and is a board-certified toxicologist (i.e., DABT) with over 40 years of experience in Environmental Risk Assessment. Dr. Dourson's specialized knowledge of the issues and pitfalls involved in the research and development of human health risk assessments along with his cutting-edge toxicology expertise allows him to provide state-of-the-art science assessments for attorneys representing plaintiff and defense.
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