IARC Strikes Again, Misguidedly

By Susan Goldhaber MPH — Dec 12, 2023
In a move that will significantly expand the restrictions on per- and poly-fluoroalkyl substances (PFAS) – more commonly known as the “forever chemicals” – the International Agency for Research on Cancer has reclassified perfluorooctanoic acid (PFOA) as “carcinogenic to humans.” It did so even though no valid studies show it increases the risk of causing cancer in people. How will this reclassification increase pressure in Europe and the U.S. for more action? Here's a look.
Image by PublicDomainPictures from Pixabay

As we have seen with glyphosate, IARC’s assessment, even if contradicted by many other governmental agencies, can result in the banning of compounds and billions of dollars in unnecessary lawsuits. Europe has led the way in PFAS distortion, with the European Chemicals Agency (ECHA) proposing to ban all PFAS, affecting more than 12,000 chemicals, with the definition of PFAS so broad it includes almost any chemical that contains fluorine.

I previously interviewed Tommaso A. Dragani, the Chief Scientific Officer of Aspidia, about Europe’s proposed ban on all PFAS and drew on his expertise again with some questions about the effect of IARC’s revised cancer classification for PFOA.      

My Interview with Dr. Dragani

SG: How will IARC’s revised classification of PFOA affect Europe’s proposed ban on all PFAS, that you previously wrote about?

TD: The updated IARC classification of PFOA is expected to support the European initiative to ban all PFAS. However, it's important to note that the IARC classification covers only two chemicals. PFOA is the only one identified as a human carcinogen (PFOS has been classified in group 2B, possibly carcinogenic to humans). In contrast, ECHA's proposed ban covers 12,000 chemicals. This includes substances such as fluoropolymers that do not have the ability to enter our bodies and can, therefore, be classified as polymers of low concern.

SG: What other consequences will the IARC reclassification have in Europe? Are there specific industries that will be particularly affected?

TD: Given that PFOA is virtually no longer produced in Europe, IARC's reclassification of PFOA as a human carcinogen could have a significant impact on industries involved in the disposal of industrial waste. I expect the cost of disposing of PFOA-containing waste and remediating PFOA-contaminated soil or water to increase.

In addition, there could be an increase in requests for analyses of possible environmental contamination by PFOA; in fact, a lot has been done in the U.S. and very little in European countries. I am thinking, for example, of areas near airports.

SG: Will the IARC reclassification affect the management of PFAS by bioremediation, and if so, how?

TD: I expect that the IARC's reclassification of PFOA could provide an incentive to fund research into managing PFAS through bioremediation. In fact, the methods currently in use, which mainly consist of burning activated carbon as a PFAS-absorbing filter and disposing of PFAS-contaminated soil in landfills, are very expensive, consume a lot of C02, and have a significant impact on the environment.

SG: What consequences could the PFOA reclassification have in the U.S.? 

TD: In the United States, I believe the consequences of the new IARC classification of PFOA will be the same as in Europe, with the likely addition of an increase in litigation related to PFOA damages, particularly from those who were exposed to PFOA because they lived in a contaminated site and developed kidney or testicular cancer.

However, it's important to note that the IARC classification of PFOA does not replace the evaluation of the cause-and-effect relationship between exposure and disease. Rather, it merely indicates that exposure to PFOA may pose a cancer hazard. The burden is on the potential plaintiff to establish a causal link between the exposure and the alleged disease.

IARC’s cancer classification

As stated by Dr. Dragani, IARC identifies the strength of evidence that a substance can cause cancer (it’s cancer hazard) but does not identify the likelihood that it will cause cancer (it’s cancer risk).  The cancer risk depends on the type and amount of exposure. Many substances identified by IARC as Group 1 carcinogens will never cause cancer, primarily because the amount that people are exposed to is way below the amount needed to cause cancer.

The core of the problem is that the public will never understand the difference between hazard and quantifiable risk. Unfortunately, agencies fail to explain the difference to the public and often hide behind potential hazards instead of evaluating actual risk.

IARC classifies chemicals for cancer by evaluating all pertinent epidemiological studies (human), cancer studies in laboratory animals, and mechanistic studies (usually in cells, tissues, and blood) and categorizing the degree of evidence in each of the three categories ranging from inadequate to sufficient.

  • Group 1 (the agent is carcinogenic to humans)
  • Group 2A (the agent is probably carcinogenic to humans)
  • Group 2B (the agent is possibly carcinogenic to humans)
  • Group 3 (the agent is not classifiable as to its carcinogenicity to humans).

PFOA was previously classified as a Group 2B, “as possibly carcinogenic to humans” in 2014 and is now reclassified by IARC as Group 1, “carcinogenic to humans" based on:

  • "Sufficient" evidence of cancer in laboratory rats showing an increase in liver, Leydig cell, and pancreatic acinar cell tumors. However, because of differences in responses between rats and humans, these tumors are unlikely to occur in humans.   
  • "Strong" mechanistic evidence in exposed humans, including studies in human cells, tissue, or blood. These studies look at “epigenetic alterations,” changes to the DNA that occur outside genes, such as increases in microRNA or DNA methylation and immune suppression, including decreases in antibody levels. But, these studies were never intended to demonstrate a substance causes cancer. At best, these studies may indicate a mechanism by which a substance may cause cancer – they are not primary evidence of causation.       
  • "Limited" evidence of excess cancer risk in humans for renal cell carcinoma and testicular cancer. The limited evidence for renal cell carcinoma (RCC) comes from one study in which the diagnosis of RCC was made 2 to 18 years after blood levels of PFAS were drawn; this one measurement was used as the basis for the conclusion that RCC patients had higher levels of PFOA in their blood than controls despite confounding by obesity and hypertension known risk factors. IARC ignored the results of other studies that have shown an increase in RCC only at very high levels of PFOA  or no increase at any exposure levels

The limited evidence for testicular cancer comes from an ecological analysis performed by a Working Group within IARC based on orchiectomies (surgical removal of testicles) from a region in Italy demonstrating a “positive association.” The analysis remains unpublished, and the data is unavailable for review. [1]

It is time for IARC to be more transparent. IARC’s classification of PFOA in Group 1, “the agent is carcinogenic to humans,” is a definitive statement that PFOA causes cancer that runs counter to the findings of other scientists. As Dr. Dragani explained, Europe’s proposed ban on PFAS could impact 12,000 chemicals, and this issue could have a significant impact for years to come.  

[1] This is contrary to the preamble of the IARC monographs that states that unpublished material may only be used if it is “publicly available and whose content is final, if there is sufficient information to permit an evaluation of the quality of the methods and results of the studies.”

ACSH relies on donors like you. If you enjoy our work, please contribute.

Make your tax-deductible gift today!



Popular articles