Frequently asked questions about per- and polyfluoroalkyl substances (PFAS)
FAQ created by the German Federal Institute for Risk Assessment (BfR) on 5 November 2019
Per- and polyfluoroalkyl substances (PFAS) are industrial chemicals which are used in several industrial processes and consumer products, due to their special technical properties. This group of substances includes at least 4,000 different compounds. In animal experiments, some of them have been found to cause liver damage, reproductive toxicity, and to be potentially carcinogenic.
In the perfluoroalkyl substances sub-group, perfluorooctanoic acid (PFOA) and perfluorooctane sulfonic acid (PFOS) are the most thoroughly studied compounds. Like all PFAS, these two compounds are not readily degradable in the environment, and are now detectable everywhere - in the environment, in the food chain, and in humans. In 2018, the European Food Safety Authority (EFSA) published a reassessment of the health risks posed by PFOA and PFOS in food.
For the reassessment, EFSA relied for the first time primarily on data from studies showing the correlation between the levels of PFOS/PFOA in the blood and changes in biological parameters which may eventually increase the occurrence rate of certain diseases among the population in the long term.
The use of PFOS has been heavily restricted already since 2006. A worldwide ban on the use of PFOA is expected to enter into force in 2020. This means that, inter alia, it will be forbidden to make and market products containing levels of PFOA, its salts or precursors exceeding a certain limit value.
The German Federal Institute for Risk Assessment (BfR) has compiled a list of questions - and their answers - on the subject of PFAS.
What are PFAS, PFOA and PFOS?
Per- and polyfluoroalkyl substances (PFAS) are industrially produced substances which do not occur naturally. They are organic compounds in which hydrogen atoms bound to carbon atoms are completely (perfluorinated) or partially (polyfluorinated) replaced by fluorine atoms. In total, this group of substances includes at least 4,000 different compounds.
The various PFAS differ in the length of their carbon chains and the functional groups present in the molecule. The long-chain compounds perfluorooctanoic acid (PFOA) and perfluorooctane sulfonic acid (PFOS) are the most thoroughly studied compounds. Along with other related compounds, they belong to the so-called “C8 Fluorochemistry”. Meanwhile, the industry has started using other compounds as alternatives to PFOS and PFOA, e.g. PFAS with shorter perfluorinated carbon chains. Numerous so-called precursor compounds, e.g. PFAS that contain ether linkages, are also in use. Some of the precursors with longer chains can be transformed into PFOA or PFOS in the environment again.
Do the acronyms "PFT" and "PFC" also refer to the "PFAS" substance group?
Apart from the term "PFAS", the terms "perfluorinated surfactants (PFT)" and "perfluorinated and polyfluorinated chemicals (PFC)" are frequently used. However, both terms only cover part of the PFAS and not the entire substance group, even when they are used in such a way in public. In addition, the acronym "PFC" is easily misunderstood, because it is also used to refer to the perfluorocarbons group.
Which products contain PFAS, PFOA and PFOS?
The industrial chemicals in the PFAS group - such as PFOS and PFOA - have been used in numerous industrial processes, technical applications, and in certain consumer products since the middle of the 20th century due to their unique technical properties. These compounds may also be present in consumer products, as impurities or unintended by-products.
PFOA is used, for example, as an emulsifier (an auxiliary material with which to mix two non-mixable substances) in the production of certain synthetic compounds, and is therefore part of various industrial interim products. The finished product may contain residues of PFOA - for instance in membranes (e.g. from “PTFE”) in breathable clothing, or in the non-stick coating of food contact materials (e.g. pans). Water, oil and dirt repellent textile coatings (e.g. on outdoor clothing, protective work wear, and upholstered furniture) may contain PFOA residues as unintended by-products or impurities. In addition, there are several technical uses of PFOA and its precursors (e.g. in fire extinguishing foams).
Until 2006, PFOS was used in certain fire extinguishing foams, which were used - inter alia - in airports. In addition, PFOS-related compounds were used for coating e.g. upholstery, carpets, pizza boxes, baking paper, and other food contact materials to make them stain resistant, grease proof, and water repellent. Furthermore, PFOS was used in ski waxes and waterproofing sprays. In 2006, the European Commission placed strict restrictions on the use of PFOS. For example, there is a limit value of one microgram (µg) pro m2 for textiles. Today, the substance is only permitted for special applications, including in the electroplating and aerospace industries.
How do PFAS get into the environment and the food chain?
PFAS have strong and stable chemical bonds, especially between their carbon and fluorine atoms. Therefore, they are hardly broken down by means of natural degradation mechanisms such as solar radiation, microorganisms and other processes. This means that PFAS released into the environment are very stable (persistent). Some PFAS can be transported to remote areas through the atmosphere. As a result, PFAS can be detected worldwide in water, soil, plants, and animals, and can therefore enter the food chain.
PFAS can be released into the environment during industrial production or use, and also during waste and sewage disposal. Products treated with fluorine compounds, e.g. fluorinated polymers, containing PFAS as impurities, residues or degradation products, may contribute to a small extent to the release into the environment. Another source is waste-water from airports, which is produced when fire extinguishing foams containing PFAS are used. A further source is industrial waste containing PFAS, for example in cases when the material is composted and then applied to fields. Subsequently, rainfall can cause leaching of PFAS from the fields into the groundwater and surface waters.
Can PFAS also be detected in humans?
The compounds are detected worldwide through studies of human blood and breast milk. This so-called "internal exposure" varies, depending on the compound.
According to a 2009 publication by the German Environment Agency (Umweltbundesamt - UBA), the PFOA levels in the blood plasma of the majority of the German population (95th percentile) are below 10 micrograms (µg) per litre:
For PFOS, this publication (2009) recorded levels of lower than 10 μg (children under 10 years) to 20 μg (women) or 25 μg (men) per litre of blood plasma (reference values for the population of Germany, in studies carried out between 2003 and 2007).
Recently, lower reference levels of 3 μg per litre for PFOA and 5 μg per litre for PFOS have been derived for children aged 3-17, based on current data regarding blood plasma concentrations.
It can be assumed that there is also a trend towards decreasing levels of PFOA in the blood plasma of the general adult population. However, no current representative data is available for this population group in Germany at this time.
Measurements of PFOS and PFOA concentrations in the blood of the general population in Germany have actually indicated a trend towards decreasing levels since 2009.
A recent study on PFOS and PFOA concentrations in the blood, in which 158 people from Munich participated, suggests that levels have further decreased in recent years. Nevertheless, this study is not representative of the total population of Germany. The data available suggests that in certain areas of Germany - so-called hot spots - there are higher PFOS and PFOA levels in the environment, which are also linked to higher human exposure.
What are the main sources of PFAS for the consumer?
PFAS are mainly ingested through food and drinking water. Other sources include indoor and outdoor air, house dust, and contact with consumer products which are made with chemicals containing PFAS. Current publications show that, to some extent, other PFAS - such as the so-called precursor compounds - can be transformed into compounds such as PFOA and PFOS, which are then ingested by consumers.
Which foods are the main sources of PFAS?
PFAS are detectable in both foods of plant and of animal origin. Consumers ingest PFAS through different food groups - mainly drinking water, fish and other seafood. Other animal products - especially offal, but also milk and dairy products - and plant foods may contain measurable levels of PFAS. Compared to meat, higher levels of PFAS are detected in offal. However, as the consumption of offal is relatively rare in Germany, the intake of PFAS via these foods makes only a minor contribution to the overall PFAS intake of the general population.
Data on levels of PFAS in food is collected in Germany as part of the Food Monitoring Programme of the Federal States ("Laender"). In most of the food samples examined by the state authorities, by means of the current analytical methods, no PFAS were detected.
Is there a maximum level for PFAS in food products?
To date, there is no legally determined maximum level for PFAS in food products. For drinking water, a guide value of 0.1 microgram (µg) per litre has been set for PFOS and PFOA.
What are the intake levels of PFOA and PFOS for consumers through food products?
The database on concentrations of PFOS and PFOA in food, on which the current Opinion of the European Food Safety Authority (EFSA) is based, has been expanded compared to the database used in previous exposure assessments. The data for Germany comes from the Food Monitoring Programme of the Federal States ("Laender"). It must be noted that the levels in the majority of the food samples which were tested using the current analytical methods were below the detection limits. Therefore, there are still uncertainties regarding the levels in food products. More sensitive analytical methods for PFOS and PFOA should therefore be developed for food monitoring.
According to the 2018 EFSA calculation, the total mean dietary weekly intake of PFOA and PFOS for the adult population in Europe is up to 14 nanograms (ng) of PFOS and 5 ng of PFOA per kilogram (kg) of body weight. The intake levels for infants, toddlers, children and adolescents can be significantly higher.
What are the health effects of PFAS?
Consumers only take in small quantities of PFAS every day. Human health risk assessments focus on long-term intake and accumulation. The long-term PFAS concentration in the body is the key factor for the extent of the health risk. The long-term intake can be determined on the basis of the measurable concentration of PFAS in the blood.
Animal experiments have shown that the compounds PFOA and PFOS can damage the liver, cause developmental toxicity, and be potentially carcinogenic. However, they do not cause DNA damage. Regarding the carcinogenic effect, it can therefore be assumed that intake levels can be defined that do not lead to any health effects. Below these intake levels, the carcinogenic effect does not occur. PFOA and PFOS can also have an impact on fat metabolism, thyroid function and the immune system.
Are PFAS - specifically PFOA and PFOS - metabolised in the body?
Studies have shown that the human body cannot metabolise long-chain PFAS such as PFOA (perfluorooctanoic acid) and PFOS (perfluorooctane sulfonic acid). The substances are excreted unchanged very slowly - primarily in urine; their half-lives are in the range of several years. A half-life is the period of time required for the concentration of a substance in the body to decrease by half, by means of biochemical and physiological processes (metabolism and excretion).
PFOA and PFOS accumulate in the body. Animal experiments have shown that animal species such as rat, mouse, dog and ape can - depending on the species and sex of the animal - excrete these substances significantly faster than humans.
PFAS with shorter fluorinated carbon chains than PFOS and PFOA are more soluble in water, and are excreted more quickly in urine than the long-chain compounds in all of the mammals studied, including humans. Compared to laboratory animals, however, short-chain PFAS excretion is also much slower in humans.
Are there health-based guidance values (e.g. TWI) for PFAS?
A TWI value describes the amount of a substance that can be ingested weekly over a lifetime without risk of adverse health effects. On 13.12.2018, the European Food Safety Authority (EFSA) derived new TWI values for PFOA (perfluorooctanoic acid) and PFOS (perfluorooctane sulfonic acid), based on the results of epidemiological studies. These studies showed correlations of increased blood serum levels of PFOS and PFOA with certain biochemical parameters, namely increased serum cholesterol levels (correlation with both PFOS and PFOA) and reduced serum antibody production after certain vaccinations in children (correlation with PFOS).
For PFOA, EFSA derives a TWI value of 6 nanograms (ng) per kilogram (kg) of body weight per week, and for PFOS a TWI value of 13 ng per kg of body weight per week. EFSA assumes that all population groups, including newborns - the most sensitive group - will be sufficiently protected by these health-based guideline values that were derived based on human data.
What happens if these health-based guidance values for PFOA and PFOS are slightly or moderately exceeded in the short term?
If the TWI (Tolerable Weekly Intake) is exceeded in the short term, impairments to the health of the consumer - including infants and children - are not to be expected due to the low acute toxicity of PFOA and PFOS. However, also a short-term exceedance of the TWI value may contribute to higher internal exposure of the organism in the long term, due to the long half-life of the substances.
What happens if EFSA's health-based guidance values for PFOA and PFOS are exceeded in the long term?
A TWI value describes the weekly intake of a substance which does not lead to any health effects among the population in the event of lifetime exposure. According to EFSA's exposure assessment, the new TWI values for PFOS and PFOA in Europe are exceeded in parts of the population. The exposure assessment for the population in Germany shows that the TWI value of PFOS is not exceeded with mean consumption quantities, but is exceeded () in the age groups of toddlers and the elderly with high consumption quantities (95th percentile). For PFOA, the exposure of toddlers and children exceeds the TWI value in the case of mean consumption, and the exposure of all age groups up to 18 years exceeds the TWI value if high consumption quantities are assumed (95th percentile). Levels of the compounds in the blood represent suitable parameters for estimating long-term total exposure to PFOS and PFOA because of the long half-lives of the substances in humans.
Recent studies carried out in an urban area in Germany in 2016 show that those blood levels on which the newly derived TWI values for PFOS and PFOA are based, are not exceeded. However, data collection in these studies was not representative of the total population, so that they can only be used to a limited extent for risk assessment.
According to the current opinion of EFSA, long-term TWI exceedance may be associated e.g. with changes in fat metabolism (increased total cholesterol level). Cholesterol is one of the known risk factors for cardiovascular diseases. Epidemiological studies show this correlation for persons over the age of 40 years. However, there are other factors that have a significant impact on the risk of such diseases. These include age, gender, certain lifestyle habits (such as smoking) and blood pressure levels. To date, there is no reliable epidemiological evidence for a relationship between the concentrations of PFOS and PFOA in the blood and an increased risk of these diseases among particularly exposed population groups. Therefore, the current assessment of health risks from exposure to PFOS/PFOA, based on the current TWI values set by EFSA, is subject to uncertainties.
In addition, external intake levels of PFOS and PFOA which are in the range of TWI values for a certain period of time do not necessarily cause blood levels to enter the critical range. Depending on the already existing blood levels, it may take years until intake levels in the range of the TWI cause blood levels to enter the critical range.
Overall, from the point of view of the BfR, there are considerable uncertainties with regard to the exposure data, the evidence of causality, and the clinical relevance of the effects which were taken as a basis for the TWI derivation.
In the opinion of the BfR, further research is required. Inter alia, topics include the question of the causal relationship (causality) and the health relevance of the observed effects. Despite the need for scientific research, the BfR recommends that assessments of PFOS and PFOA in food products should be based on the new health-based guidance values derived by EFSA.
Has the use of PFOA and PFOS meanwhile been banned?
PFOS meets the criteria for classification as a persistent organic pollutant (POP) pursuant to the Stockholm Convention, and is regulated in the EU by Directive 2006/122/EC. The production, marketing and use of PFOS and its associated compounds (derivatives) are thereby restricted to the greatest possible extent within the EU.
The production, use, marketing and import of PFOA will also be restricted to the greatest possible extent within the EU from 4 July 2020 (see link below). For textiles, for example, there will be a limit of 25 micrograms (μg) per kilogram (kg) (PFOA) or 1000 μg per kg (PFOA-releasing substances). Exceptions or longer transitional periods exist for some special uses. In addition, PFOA as well as perfluorinated acids with a carbon chain length of C9 to C14 have been added to the European Candidate List of Substances of Very High Concern (SVHC).https://eur-lex.europa.eu/legal-content/DE/TXT/PDF/?uri=CELEX:32017R1000&from=DE
Are PFAS used in packaging materials for food products?
The European Commission has laid down restrictions on the use of PFAS in the production of plastics which come into contact with food products, in order to prevent or avoid intake of PFAS by the population through these materials to the greatest possible extent. Example PFOA: For this substance, its salts, or precursors as part of another substance (e.g. in food packaging), the EU-wide limit of 25 micrograms (μg) per kilogram (kg) for PFOA and its salts, and 1000 μg per kg for precursor compounds will apply from the year 2020 onwards.
Are PFAS used to manufacture outdoor clothing?
Fluorinated polymers, also referred to as fluorocarbon resins, are used to coat textiles in order to repel water, oil and dirt. This coating firmly bonds to the material. As a result of the production process, such coatings may contain residues of PFOA and its precursor compounds. Here, PFOA can also occur as an unintended by-product in production processes which are C8-Fluorochemistry-based. Meanwhile, the industry mainly uses a "C6-Fluorochemistry"-based alternative technology for coatings, which reduces the residual content of PFOA. There are also fluorochemical-free technologies to make textiles such as outdoor clothing water-repellent.
Are there any health risks associated with wearing outdoor clothing?
In addition to the fluorochemical-free variants of the water-repellent coating of clothing, the residual PFOA content has been reduced by the new "C6-Fluorochemistry" technology, so that only traces of it are detected in the product. PFOA is not firmly bound to the textile fibre, and may be released when wearing or washing the clothing. In the view of the BfR, wearing a jacket which has been produced using state-of-the-art technology does not, according to current knowledge, pose any health risks, also because the skin is a good protective barrier against PFOA. The main source of PFOA intake for consumers is food. In contrast, the likelihood of potential direct intake through outdoor clothing is negligibly small.
How does the BfR assess the use of short-chain PFAS?
As an alternative to the "C8-Fluorochemistry", PFAS with shorter perfluorinated carbon chains ("short-chain PFAS"), e.g. the "C6-Fluorochemistry", are meanwhile used in the industry. Short-chain PFAS are excreted much faster than long-chain ones following absorption into the human and mammal organism.
Data from animal experiments on short-chain PFAS - e.g. perfluorohexanoic acid (PFHxA), which includes a chain of six carbon atoms - suggest similar toxicological effects. However, the impact seems to be lower compared to that of long-chain PFAS because the toxic effects of the short-chain compounds were observed only in higher doses. Only a limited amount of toxicological data is currently available for these substances.
There are currently no health-based guidance values, e.g. TWI values (Tolerable Weekly Intake values) that could be applied in the assessment of health risks related to the presence of short-chain PFAS in food.
If short-chain compounds are to be increasingly used as alternative substances in manufacturing in the future, this may, in the opinion of the BfR, lead to an increased intake due to their persistence in the environment. The BfR recommends continuing to monitor the levels of long-chain and short-chain PFAS in foods, especially in areas with conspicuously high levels (so-called hot spots), and to avoid releasing these substances into the environment to the greatest possible extent.
What are the BfR recommendations for consumers?
Consumers can influence their contact with or intake of PFOA and PFOS only to a limited extent. This applies in particular to food and drinking water. A change in dietary habits in this respect is not necessary. In areas with relatively high background levels (hot spots), the BfR refers to the recommendations of the respective federal state authorities.
Do PFOA and PFOS enter into breast milk?
Analysis of breast milk samples shows that PFOA and PFOS can also be detected in breast milk. According to different studies, the concentrations of PFOS and PFOA measured in breast milk are approximately 0.9 % to 2 % and 1.8 % to 9 %, respectively, of the concentrations measured in the blood of the mother.
What are the BfR recommendations for breastfeeding mothers?
Due to the internal exposure of the mother, PFOA and PFOS can be expected in low amounts in breast milk and have in fact also been detected in breast milk samples. However, a health impairment caused by PFOA and PFOS is not to be expected under the current levels of exposure in Germany. This applies also to infants who are breastfed long-term and receive only breastmilk during the first months of their life.
Further information on the subject on the BfR website:
Publications about PFAS on the BfR website
XXXVI. Paper, cardboard and paper board for food contact material, BfR recommendation XXXVI, last updated 01.07.2016
This text version is a translation of the original German text which is the only legally binding version.