PFASs: very persistent chemicals

What are PFASs and where are they found?

Per- and polyfluoroalkyl substances (PFASs) are a large class of over 4000 chemical compounds. Due to their non-stick, waterproof and heat-resistant properties, PFASs have been widely used since the 1950s in various industrial fields and everyday consumer goods: textiles, food packaging, fire-fighting foams, non-stick coatings, cosmetics, plant protection products, etc.

These chemicals are very common and are classified differently according to the number of carbon atoms they contain. The more carbon atoms there are, the more persistent they are in the environment. Two of the best-known PFASs, perfluorooctanoic acid (PFOA) and perfluorooctane sulfonic acid (PFOS), have the highest levels of environmental persistence.

Food, especially seafood, is a significant source of human exposure to these compounds. For everyday foods, the highest concentrations of PFOA and PFOS are found in crustaceans and molluscs. Drinking water (DW) can also be a source of contamination.

In recent decades, long-chain perfluorinated compounds have been partly replaced with short-chain perfluorinated compounds, which are more mobile in soils, for example, but are still persistent and can have equivalent levels of concern.

Where are PFASs found in the environment?

Given the many varied uses of these chemical compounds, combined with their very high persistence, they contaminate all environmental media: water, air, soil and sediment. Some accumulate in living organisms – plants and animals – and end up in the food chain. Others, which are more mobile, are transported over very long distances via water or air and can even be found in faraway oceans.

What are the sources of exposure to PFASs?

Over the years, these properties of persistence, mobility and accumulation in living organisms have led to the human population being increasingly exposed to PFASs.

According to EFSA (2020), seafood, eggs and meat are the foods that contribute most to PFOS and PFOA exposure. Drinking water can also be a source of exposure, as can indoor and outdoor air, dust and contaminated soil. Occupational exposure to PFASs can occur in a number of industrial sectors, including the chemical industry, textile processing and electronics manufacturing, as well as from their use in fire-fighting. The highest blood contamination levels are found among workers at PFAS manufacturing sites (ECHA, 2023).

Why are these compounds of concern to health?

Scientific studies on certain known PFASs show that they can have harmful effects on humans: increased cholesterol levels, cancer, effects on fertility and foetal development, on the liver, kidneys, etc. They are also suspected of interfering with the endocrine (thyroid) and immune systems. In December 2023, the International Agency for Research on Cancer (IARC) classified PFOA as "carcinogenic to humans" (Group 1) and PFOS as "possibly carcinogenic to humans" (Group 2B).

"Faced with this very large class of substances, which are particularly persistent in the environment, the difficulty lies in identifying or distinguishing those with the hazard characteristics of greatest concern. This calls for research to be speeded up into substances, particularly those most commonly found in the environment, and the development of innovative approaches to characterise their toxicity", explains Matthieu Schuler, Managing Director General of the Science for Expertise Division at ANSES.

How are PFASs regulated?

At international level 

The Stockholm Convention (2001), an international agreement aimed at controlling certain persistent organic pollutants, regulates several compounds in the PFAS class at worldwide level. Since 2009, the production and use of PFOS has been restricted to a list of specific acceptable purposes (photo imaging, certain photo-resist and anti-reflective coatings, an etching agent for compound semiconductors and ceramic filters, aviation hydraulic fluids, metal plating in closed-loop systems, certain medical devices, fire-fighting foam, certain insect baits). PFOA has been prohibited from import, export, production and use, unless specifically exempted, since 2020. The perfluorohexane sulfonic acid (PFHxS) class, as well as its salts and related compounds, is shortly expected to be included in the Convention.

In Europe

In Europe, several ongoing initiatives are seeking to extend the Stockholm Convention to other substances in the class of perfluorinated compounds. In 2020, the European work on this topic was highlighted, in line with the EU Chemicals Strategy for Sustainability.

Via Regulation (EC) No 1907/2006 (REACH Regulation)

The Strategy specifically mentions PFASs as being a priority topic for risk management. In this context, a comprehensive restriction proposal on PFASs presented by five Member States – Sweden, Norway, Denmark, the Netherlands and Germany – was submitted in January 2023 and is currently being examined by the European Chemicals Agency (ECHA). It proposes a ban in Europe on the manufacture and placing on the market of substances, mixtures and articles containing PFASs on the basis of their persistent nature. Some exemptions, most of which are time-limited, are proposed for certain uses depending on the availability of applicable alternatives.

This restriction supplements the proposal submitted by ECHA in January 2022 concerning more specifically the ban on PFASs in fire-fighting foams. The procedure is under way at European level.

Regulation in drinking water

Monitoring of PFASs in drinking water was introduced by European Directive (EU) 2020/2184 of 16 December 2020 on the quality of water intended for human consumption. To date, a quality limit of 0.10 µg/L has been set for the sum of 20 PFASs in drinking water. Another parameter, "PFAS total", was also introduced with a related quality limit of 0.50 µg/L: its purpose is to include all the PFASs that can be measured in water.

This directive was transposed into French law in January 2023. The amended Ministerial Order of 11 January 2007 incorporates the 0.1 µg/L quality limit for the 20 PFASs, while systematic screening for PFASs will be included in the Regional Health Agencies' quality monitoring of drinking water from 1 January 2026. However, from 1 January 2023, any situation where the new quality limit is exceeded must be taken into account.

Moreover, PFOS and its derivatives appear on the list of priority substances in the Water Framework Directive. They are therefore included in EU-level monitoring and control of water bodies to improve the quality of surface and ground water, in terms of both chemical and ecological status. In France, the amended Ministerial Order of 25 January 2010 established the monitoring programme for the status of water in application of Article R. 212-22 of the French Environmental Code. This order, amended in 2022, incorporates the 20 PFASs listed in the aforementioned Directive (EU) 2020/2184 of 16 December 2020 for groundwater, as well as PFOS for surface water.

Regulation in food

Since 1 January 2023, four PFASs have been regulated in certain foodstuffs of animal origin (fish, molluscs, crustaceans, eggs, meat and offal from slaughter animals, poultry and game) as part of their placing on the market (Regulation (EU) 2023/915): in the event of non-compliance, the products cannot be offered for sale. However, there are no limit values for foodstuffs produced by individuals for their own consumption.

In addition, the European Commission issued recommendations ((EU) 2022/1431 and (EU) 2022/1428) in order for Member States to monitor levels of several PFASs in foodstuffs during the years 2022 to 2025. 

What work has ANSES carried out with regard to these compounds?

The Agency has been studying the issue of PFASs for many years. It has already carried out major work to:

• better understand the uses, sources of exposure and toxicity of these compounds;
• establish toxicity reference values for certain substances;
• assess the risks associated with the release of PFOA by non-stick coatings of kitchen utensils;
• draw up an inventory of PFAS levels in water resources and drinking water.

The Agency also strongly supports the PFAS restriction proposal presented at European level in order to reduce emissions of these substances at source. In this regard, it contributed to the public consultation organised in 2023 and stresses the importance of monitoring these substances. In addition, ANSES has devoted resources to the European expert committees tasked with assessing restriction work under the REACH Regulation.

At the same time, and without waiting for a regulatory framework to be put in place, ANSES is taking action to support the French authorities in advancing knowledge and establishing scientific benchmarks (TRVs, guideline values, etc.) with a view to reducing exposure.

As an example, in late 2023, ANSES conducted a survey of existing reference values (RVs) for drinking water for the 20 PFASs listed in Directive (EU) 2020/2184.

In 2024, the Agency is continuing its work to review existing surveillance schemes, define a methodology for prioritising the PFAS substances to be monitored, and propose toxicity reference values for long-term oral exposure.

In addition, ANSES has included PFASs in its total diet study, the third edition of which is currently being conducted. This is expected to clarify the dietary exposure levels of the general population.

The study of this class of substances has also been included in the European Partnership for the Assessment of Risks from Chemicals (PARC). Coordinated by ANSES, this major project is seeking to develop next-generation chemical risk assessment in order to better protect health and the environment.