Per- and polyfluoroalkyl substances (PFAS)

PFAS consist of a fully (per) or partly (poly) fluorinated carbon chain connected to a functional group. The bond between carbon and fluorine atoms is very strong, which makes PFAS highly persistent in the environment. Therefore, PFAS are often called “forever chemicals”. 

In 2021 OECD (the international organization for economic cooperation and development) agreed on a PFAS definition where PFAS are defined as substances that contain at least one fully fluorinated methyl group (-CF3) or fully fluorinated methylene group (-CF2-) without any hydrogen, chlorine, bromine, or iodine atom attached to it. This PFAS definition is also used by the Swedish Chemicals Agency as well as the Swedish EPA.

The physicochemical properties vary among different PFAS. Varying length of the fluorinated carbon chain as well as the type of functional group influence the fate and behaviour of the substance, as well as its bioaccumulation and (eco) toxicity. In contrast to other environmental pollutants, such as dioxins and PCBs, PFAS do not accumulate in fatty tissues. Instead, they bind to proteins and accumulate in the liver, blood, lungs, and kidneys. The half-life varies from a few days up to several years for different PFAS. PFAS may also be transferred to the foetus during pregnancy or to babies during breast feeding. 

PFAS have been widely used in both industrial and consumer applications and are released during the entire life cycle of an article, from production to use and later during waste management. Their high persistence means; once PFAS have been released into the global environment, they will stay there for a very long time. The combination of an extensive use and the inherent properties has led to PFAS being ubiquitously distributed in the global environment, biota and humans, and even in remote unexploited areas, which means they also have a high long-range transport potential. This situation has caused a diffuse exposure to PFAS, and more or less all humans have slightly elevated levels of PFAS in their blood. Some PFAS are more water soluble and therefore water may be their main route of transport, while other PFAS are volatile and may be transported through the air or by airborne particles and water droplets.

Perfluorinated carboxylic acids (PFCAs), such as perfluorooctanoic acid (PFOA), and perfluorinated sulfonic acids, such as perfluorooctanesulfonic acid (PFOS), are the most well-known and studied PFAS. As the use of PFOS and PFOA (and their precursors, i.e. substances that can degrade into PFOS and PFOA) have been restricted they are being replaced with other PFAS. However, these replacement PFAS are often similarly persistent, and their inherent toxicity is often unknown. This is referred to as “regrettable substitution”.

There is a report commissioned on behalf of the Swedish Chemicals Agency with the objective to provide a broad and easy-to-understand guide to introduce the PFAS issue to non-experts, for example, officials and environmental officers with some scientific background. The report can be downloaded from the Swedish Chemicals Agency’s website: PM 3/22 Overview of knowledge on PFAS (kemi.se)

In Sweden, there are many government agencies involved in supervision and regulatory development in areas where PFAS occur, for example:

• the Swedish Food Agency is the supervisory authority for drinking water and food quality, as well as materials that come into contact with foodstuffs,
• the Swedish Chemicals Agency is responsible for enforcement of legislation related to the placing on the market of chemicals,
• while the Swedish Environmental Protection Agency is responsible for our national environmental monitoring and issues pertaining to environmental law, including environmentally hazardous activities such as waste management, wastewater treatment plants and remediation of contaminated sites.

There is consensus among the EU member states that PFAS should be treated as a single group. Therefore, Sweden and four other Member States have proposed a broad restriction within the REACH Regulation, covering all PFAS in addition to those already subject to ban or a restricted use. You can read more at: PFAS (kemi.se)

There are no companies in Sweden manufacturing PFAS. However, there are those that use the substances in the manufacturing process of various products, which can cause emissions. Monitoring has also shown that emissions from wastewater treatment plants, waste incinerators for energy recovery as well as landfills and previously contaminated sites are other potential sources. Airborne deposition also contributes to increasing levels of PFAS in the Swedish environment.

In Sweden, as in many other countries around the world, high concentrations of PFAS have been found in the environment in connection to activities where large quantities of PFAS-containing aqueous film forming foam (AFFF) have been used or handled, such as firefighting training sites used by the civil fire brigades, airports and the armed forces.

The use of PFAS-containing AFFF has contaminated soils, groundwater and surface water all over Sweden and Europe. In many places, PFAS levels are high enough to pose a threat to the environment as well as to human health, for example due to the contamination of drinking water and fish for consumption.

As PFAS have been widely used in industrial and consumer applications it is difficult to identify and take inventory of all PFAS-contaminated sites that may exist. A rough estimate suggests that there are probably thousands of potentially PFAS-contaminated sites in Sweden, beside the firefighting training sites. In addition, there are few remediation techniques suited for remediation of PFAS-contaminated sites, which means remediating these sites are both difficult and costly. Thus, there is a need for developing sustainable remediation methods for PFAS-contaminated sites.

There is more information about how contaminated sites in general are managed in Sweden here: Contaminated sites

The Swedish EPA, as well as several other national authorities, are currently working together to manage PFAS-contaminated sites. In 2022, the Swedish EPA received a government assignment to focus on working with PFAS-contaminated sites. The project period is 2022-2027. This includes identifying possibly PFAS-contaminated sites in Sweden, as well as taking steps towards managing these sites, including providing further guidance on how to perform risk assessments for PFAS-contaminated sites. The Swedish EPA is working closely together with other agencies such as the Swedish Geotechnical Institute and the Geological Survey of Sweden to find a solution for how to remediate a PFAS-contaminated site. The County Administrative Boards and municipalities are also important parties of the project.

In 2015, the Swedish Geotechnical Institute derived preliminary generic guideline values for PFOS in contaminated soil and groundwater. These preliminary generic guideline values are currently under revision based on the new tolerable weekly intake of 4.4 ng/kg bodyweight/week for the sum of 4 PFAS (perfluorooctanoic acid (PFOA), perfluorooctane sulfonic acid (PFOS), perfluorononanoic acid (PFNA), perfluorohexane sulfonic acid (PFHxS)) recommended by the European Food Safety Authority in September 2020. The Swedish Environmental Protection Agency is currently conducting a socio-economic impact assessment for the proposal for new guideline values for PFAS. The analysis is expected to be completed in the autumn of 2025 and will form the basis for decisions on possible new generic guideline values for PFAS in Sweden.

As with the Swedish EPA’s generic guideline values for other pollutants in soil, the preliminary guideline values for PFAS in soil and groundwater are not legally binding values but rather a tool in the risk assessment of contaminated sites.