Tom Neltner, J.D., Chemicals Policy Director and Maricel Maffini, Ph.D., Consultant
In June, the Food and Drug Administration (FDA) posted a webpage that serves as a helpful starting place to learn about the agency’s efforts and plans regarding per- and poly-fluoroalkyl substances (PFAS) in food. The webpage explains that FDA is “assessing food for PFAS through sampling” and is “reviewing the limited authorized uses of PFAS in food contact applications.” In a statement accompanying the webpage’s release, FDA’s acting and deputy commissioners assured the American people that the agency “does not have any indication that these substances are a human health concern, in other words a food safety risk in human food, at the levels found in this limited sampling.”
We were surprised by FDA’s statement that all is fine given the results the agency published and the evidence about the array of health risks posed by PFAS at extremely low levels. Although the information posted is useful, we found it confusing and vague in some important aspects. Therefore, we are taking the opportunity here to raise some issues concerning FDA’s statements and planned next steps on PFAS. Additionally, in another blog, we discuss the implications of FDA’s statements on its review of 62 authorized PFAS uses in contact with food and make recommendations to the agency as it proceeds with this promising effort.
FDA needs to show how it reached such a broad conclusion of safety
FDA refers to PFAS as a “family of human-made chemicals” and explains that “[t]here are nearly 5,000 types of PFAS, some of which have been more widely used and studied than others.” From this statement, it seems that FDA considers any substance with at least one fully fluorinated carbon to be a PFAS, in agreement with the international community.
Of this family, the agency tested a variety of foods for 16 PFAS with a number of fully-fluorinated carbons ranging from 3 to 16 split evenly between short-chain (less than 8 carbons in a chain) or long-chain (8 or more carbons). It is unclear why the agency selected those PFAS; what’s clear is that none of the 16 were PFAS the agency allows to be intentionally added to food packaging.
While FDA measured all 16 PFAS in the produce samples from farmer’s markets in North Carolina and 10 in milk samples from New Mexico, it reported measuring only two, PFOS[1] and PFPeA[2], in food samples bought from stores in the mid-Atlantic region in October 2017. We described these results in a previous blog.
The agency provides little explanation for how it evaluated the data beyond two statements:
- “When there is evidence of PFAS found in food, the FDA conducts a safety assessment using the best available science to evaluate whether the levels present a possible human health concern.”
- “For PFAS found in food, the FDA currently uses the U.S. Environmental Protection Agency’s [EPA] reference doses (RfD) for PFOA[3] and PFOS of 0.02 µg/kg bw/day[4] as the most appropriate toxicity reference value (TRV).”
The RfD is the lowest exposure determined to be safe and is commonly based on toxicology information for individual chemicals. In 2016 based on this RfD, EPA issued a drinking water health advisory for lifetime exposures to combined PFOA and PFOS at 70 parts per trillion.
We took these statements to mean that FDA’s safety assessment consisted of treating PFAS as a class and applying the RfD to each member of the PFAS family and, possibly, collectively for the combined exposure to all PFAS in the diet. After checking with FDA, we learned that the RfD would only apply to long-chain PFAS – half of the 16 for which it tested – despite the broad language on its webpage. And the agency did not explain what RfD it used for 8 short-chain PFAS. We asked the agency to update its webpage to clarify the narrow scope of its statement and to explain how they were determining how much short-chain PFAS in the diet is safe in the diet.
To better understand the agency’s reasoning behind its conclusion that PFAS are not a human health concern at the levels found, and to answer the questions we’ve raised with the agency, we submitted a Freedom of Information Act (FOIA) request.
Critical gaps in FDA’s vague and confusing statements on PFAS in the diet
FDA’s response to our FOIA should provide more information, but we have three major concerns based on what the agency has made public so far:
- More PFAS in more foods may have been detected: In its summary of the mid-Atlantic region results, the agency indicated that 14 of 91 samples had detectable levels of PFAS. However, the data shows that levels found in those samples were over the Limit of Quantification (LOQ). The difference between detection and quantification is important because the LOQ indicates the amount that is accurately measured and is usually between three and ten times greater than the limit of detection. And detection means that the chemicals are present but cannot be precisely quantified. Therefore, many more PFAS in more samples may have been detected but not quantified. We seek to learn whether this is the case through our FOIA request.
- Not using emerging evidence of reduced effectiveness of vaccines: The agency says it will use the “best available science” but is using an RfD set by EPA in 2016. Subsequent analysis by the Centers for Disease Control and Prevention (CDC) in a draft toxicological profile for four PFAS, including PFOA and PFOS, indicates that EPA’s RfD is insufficient to protect the public and should be almost six times lower. The primary difference is that CDC used a greater safety factor than EPA based on evidence that four PFAS may reduce the effectiveness of vaccines – a critical public health concern.
- Drawing a bright line between long- and short-chain PFAS: In applying EPA’s RfD only to long-chain PFAS, FDA is acting inconsistent with a peer-reviewed study by its own scientists. We highlighted that study in a blog earlier this year. As we understand FDA’s study, there is no bright line between long- and short-chain PFAS in terms of their ability to bioaccumulate in the human body. Rather the evidence suggests a spectrum where, after a single exposure, short-chain PFAS remain in the body for months rather than years and are less likely than long-chain to bioaccumulate. However, exposures to these chemicals from food and drinking water are ongoing. Through the FOIA request we expect to obtain information on the RfD the agency used to support its finding that levels of short-chain PFAS in food are safe. Until we see evidence to the contrary, we believe that the suggestion that these two types of PFAS are fundamentally different is not grounded in the agency’s own science.
Conclusion
We are pleased FDA made public its position on PFAS food contamination, released the three studies as well as its commitment to review the safety of intentional uses of PFAS authorized for use in food packaging. Unfortunately, in its statement, the agency may have been too quick to conclude that PFAS are not a food safety risk in the American diet. They certainly haven’t explained how they got there. In light of the evidence we have seen, a transparent review of the safety is essential to protect public health and reestablish consumer confidence.
[1] Perfluoroctanesulfonate – a PFAS with eight fully-fluorinated carbons.
[2] Perfluoropentanoic acid – a PFAS with four fully-fluorinated carbons. Number corrected on 8/2/19.
[3] Perfluorooctanoic acid – a PFAS with seven fully-fluorinated carbons. Number corrected on 8/2/19.
[4] µg/kg bw/day means micrograms of the chemicals per kilogram of body weight per day. FDA uses 60 kilograms or 132 pounds as representative weight for adults.