Polyfluoroalkyl substances, or PFAS, are a group of man-made chemicals that includes perfluorooctanoic acid (PFOA), perfluorooctane sulfonate (PFOS), perfluorononanoic acid (PFNA), perfluorohexane sulfonic acid (PFHxS) and many others. PFAS have been manufactured and used in a variety of industries around the world since the 1940s. Certain PFAS such as PFOA and PFOS, PFNA and PFHxS, don't break down in the environment or in the human body, and can accumulate over time. Exposure to PFAS may lead to adverse health effects. People can be exposed to PFAS in different ways, for example through food. Food can become contaminated through contaminated soil and water used to grow the food, through the concentration of these substances in animals via feed and water, through food packaging containing PFAS, or equipment that contained PFAS during food processing.
Prof Dr Tanja Schwerdtle is the chair of the working group that helped EFSA’s Panel on Contaminants in the Food Chain (CONTAM) to draft its opinion on PFASs, currently under public consultation until 20 April 2020.
Could you briefly describe the work you have done? What are the main points?
We have proposed a group tolerable weekly intake (TWI) for four main PFASs that accumulate in the body, identified the most exposed population groups, and identified the critical effect linked to exposure to PFASs in animals and humans. We also identified the foods that contribute most to the exposure to these four PFASs – drinking water, fish, fruit, and eggs and their derived products.
Why did experts set a group TWI rather than individual TWIs?
In our previous opinion, in 2018, we set two TWIs, one for PFOS and one for PFOA. In this new draft opinion, we have re-assessed these two TWIs considering new scientific knowledge that became available in the meantime, including for PFAS other than those assessed in 2018. To do this, we considered EFSA’s ‘MixTox’ guidance, which was published last year and which equipped us with methodologies and tools to assess combined exposure to multiple chemicals. As a result, we set one single group TWI of 8 ng/kg body weight per week for PFOA, PFNA, PFHxS and PFOS, based on effects observed in humans.
Why have experts changed the critical effect – from impact on cholesterol to decreased response of the immune system to vaccination?
In its 2018 opinion EFSA considered increased cholesterol as the critical effect for adults due to its link to cardiovascular disease, a common public health issue.
In the meantime, new data about the effects of PFAS in animals and humans have become available and new scientific studies have been published which question the direct link between exposure to PFAS and increased cholesterol levels. This is not the case for effects on the decreased response of the immune system to vaccination, which was also identified as an important effect in the previous assessment. The proposed new TWI is also protective against other possible health effects, such as the increase of cholesterol in blood.
Who are the most exposed groups? Is this TWI protective for babies too?
Infants, toddlers and other children are the most exposed according to EFSA’s exposure assessment. Pregnancy and breastfeeding are the main contributors to exposure for infants. The new TWI was set in such a way that it should protect infants against high exposure.
What are current knowledge gaps and on which aspects are you hoping to receive more feedback during the public consultation?
We are interested in receiving, and would welcome feedback, on all aspects of our opinion. In particular, it would be helpful to receive for a broad range of food groups more occurrence data obtained with more sensitive analytical methods, allowing to detect PFAS at low levels. We would also welcome more information on the relative potencies of the 4 PFAS we assessed, but also others that are detected in food.
How can different parties contribute to the final opinion?
The draft scientific opinion is open for public consultation until 20 April 2020 and this is a good opportunity to send feedback and comments. In addition, on 12 March EFSA will organise a technical meeting in Brussels that is open to everyone. In that meeting EFSA will explain the approach we followed to draft the opinion and we will answer any questions from participants. We welcome you to have your say!