16 Environmental Laboratory - Spotlight on PFAS POLY AND PERFLUOROALKYLATED SUBSTANCES (PFAS);
THE GATHERING STORM FOR CHEMICAL REGULATORY PROFESSIONALS AND THE INDUSTRY
What are PFAS? Per- and polyfl uoroalkylated substances (PFAS) are a very large and structurally diverse group of man-made organo- fl uorine substances. They are sometimes termed ‘forever chemicals’ because of their extreme persistence. Well known examples of PFAS are perfl uoroctanoic acid (PFOA) and perfl uorooctane sulfonate (PFOS), both of which are now subject to regulatory restrictions because of their harmful properties.
T he OECD1 global working group on PFAS defi nes this group of chemicals as “fl uorinated substances that contain at least
one fully fl uorinated methyl or methylene carbon atom (without any H/Cl/Br/I atom attached to it)…any chemical with at least a perfl uorinated methyl group (–CF3) or a perfl uorinated methylene group (–CF2–) is a PFAS”. This defi nition is based purely on
chemical structure. Identifi cation of a substance as a PFAS does not necessarily mean that it is toxic1
substances that meet the PFAS defi nition vary from 4,7001 6,000,0002
the UK is unknown but likely to be much lower3
development outcomes4 . Estimates of the number of to over
. The number of PFAS in commercial use and supply in .
PFAS have been in commercial production and use since the mid-20th
century. They were fi rst used in fi re-fi ghting foams in the
1960s. They are used globally in many industrial applications and consumer products. Their high thermal and chemical stability and their water- and oil-repellent nature encouraged their wide use in consumer products such as cosmetics, coatings for textiles and paper including food contact materials. PFAS also have many industrial applications including metal electroplating, polymer and semi-conductor manufacture amongst many more.
Why are they a concern?
PFAS are extremely stable because the carbon-fl uorine bond is very strong. Their extreme persistency means that environmental exposure could be irreversible and that PFAS are technically diffi cult and costly to clean-up and destroy. Many PFAS are environmentally mobile and travel far from their source, leading to widespread contamination of environmental waters including sources used for drinking water supply. Shorter chain PFAS with a fl uoroalkyl chain less than six carbon atoms are more mobile than longer chain substances and are frequently found in environmental waters including those used for drinking water supply. Longer chain PFAS have a greater propensity to bioaccumulate in the food chain, with reports of PFAS in human tissue and blood, in plants following uptake from soil and in animals such as fi sh. A recent European biomonitoring study4 found that serum levels of PFAS exceeded safe thresholds in over 14% of teenagers sampled.
Exposure to some PFAS has been associated with a range of adverse effects on human health. These include altered immune and thyroid function, increased cholesterol, liver disease, reduced birth weight and adverse reproductive and
. However, for most PFAS there is very
little toxicological data. This is a high priority evidence gap that both scientists and regulatory authorities are seeking to rapidly address globally.
With so many uses of PFAS, there are numerous pathways of release to the environment across the full life-cycle of the substance from manufacture through use to disposal. PFAS are ubiquitous in the environment with contamination of remote areas by some PFAS reported. Higher environmental concentrations of PFAS are often associated with their use in fi refi ghting foams at airports, fi re training grounds, military sites, and major incident sites. Secondary sources of PFAS to the environment include wastewater treatment works and landfi ll sites. Research has been on-going in the UK by the Environment Agency to identify high risk sites associated with PFAS use. A useful summary of the evidence base on use and environmental occurrence of PFAS in England was published by the Environment Agency in 20213
, with further sampling for a broader range of PFAS continuing in groundwater and surface waters planned.
Current and future UK and European PFAS policy The hazardous and potentially ubiquitous nature of several PFAS has been recognised since the early 2000s when PFOS was voluntarily withdrawn from use by industry. Several PFAS are subject to global regulatory restrictions. PFOS was designated as a persistent pollutant (POP) under the Stockholm Convention6
in
2009, followed by PFOA in 2020 and perfl uorohexane sulfonate (PFHxS) in 2022. In addition, several PFAS are identifi ed under the REACH regulations7
as Substances of Very High Concern
(SVHC) and subject to restrictions on manufacture, supply and use in the European Union and the UK. Concerns related to the persistent, bioaccumulative and toxic (PBT) properties of PFAS historically underpinned these restrictions. More recently, the high persistence and high mobility of PFAS have led to restrictions of other PFAS such as hexafl uoropropylene oxide dimer acid (HFPO-DA) also known as Gen-X, based on an ‘equivalent
1
OECD (2021) Reconciling the terminology of the universe of per- and polyfl uoroalkyl substances: recommendations and practical guidance
2
Schymanski, E. P. Chirsir, T.Kondic, P. Thiessen, J. Zhiang & E. Bolton. PFAS and Fluorinated Compounds in PubChem. Online at
https://t.co/UJtd55ntye
3
Poly- and perfl uoroalkyl substances (PFAS):sources, pathways and environmental occurrence. Environment Agency Chief Scientist’s group report. Published 2021
IET JANUARY / FEBRUARY 2023
4 HBM4EU policy brief - PFAS. June 2022 5
S.E. Fenton, A Ducatman, A Boobis, J. C. DeWitt, C. Lau, C Ng,J.S. Smith,and S.M. Roberts (2020) Per‐and Polyfl uoroalkyl Substance Toxicity and HumanHealth Review: Current State of Knowledge and Strategies for Informing Future Research. Environmental Toxicology and Chemistry—Volume 40, Number 3—pp. 606–630, 2021
6Persistent organic pollutants (POPs) | UNEP - UN Environment Programme
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