Per- and polyfluorinated alkyl compounds (PFAS)
Per- and polyfluorinated alkyl compounds (PFAS)
Per- and polyfluorinated alkyl compounds(PFAS) include over 10,000 substances - such as PFOS (perfluorooctanesulfonic acid), PFOA (perfluorooctanoic acid), perfluorononanoic acid (PFNA) and perfluorohexanesulfonic acid(PFHxS) - and are industrial chemicals that have been used for decades in the manufacture of a wide range of products e.g. textiles, household goods, firefighting, automotive, food processing, construction, electronics. Ingestion of PFAS through food can result in adverse health effects. The use of PFOS has been banned in Europe since 2010, and since 2020, PFOA and substances from which PFOA can be released have been banned from use as pure substances in the EU. In mixtures and articles, maximum levels of 0.025 milligrams (mg) per kilogram (kg) or 1 mg per kg (PFOA-releasing substances) have applied since 2020. There are exemptions or longer transition periods for various specialty uses. The European Chemicals Agency (ECHA) published its proposal to ban the manufacture, use and placing on the market (including import) of at least 10,000 PFAS on February 7, 2023. The proposed ban was drafted by experts from Germany, the Netherlands, Denmark, Norway and Sweden within the framework of the EU chemicals regulation REACH.
PFASs are found in coatings for textiles such as outdoor clothing, as impregnation, in baking paper, in ski waxes or fire extinguishers. In cosmetics, they are used in mascara, makeup and lipsticks. PFASs are difficult to degrade and are now widespread throughout the environment. They are therefore also detectable in the food chain and in humans.
Humans absorb PFAS primarily through food, where these substances are most frequently detectable in fish, fruit, eggs and egg products, as well as through drinking water.
Once ingested in the body, PFAS bind to proteins in the blood and are excreted extremely slowly in humans, mainly via the kidneys. This leads to accumulation in the body, for example in the blood and liver. The half-life in the body can range from a few days and months (e.g. PFHxA, PFBA) to several years (e.g. PFOAS, PFOA, PFHxS), depending on the chain length of the PFAS. Globally, the levels of PFOS, PFOA and PFHxS in humans have been shown to be decreasing since 2000, whereas the levels of PFNA have been increasing.
PFAS pass into breast milk and accumulate in the fetal organism during the breastfeeding period. However, measurement results and modeling show that the blood levels of these compounds of long breastfed and non-breastfed children equalize within a few years.
Toxic effects due to short-term high intake (acute toxicity) are low for PFAS. Possible health effects caused by PFAS include decreased immune response to vaccination, increased cholesterol levels, developmental toxic effects in the unborn child such as delayed mammary gland development and lower birth weight, and the development of kidney and testicular cancer in adults.
Situation in Austria
Maximum levels for PFAS in food
From 01.01.2023, maximum levels for PFOA, PFOS, PFNA, PFHxS and for the sum of these 4 PFAS will apply in the EU in foods such as eggs, fishery products and shellfish, meat and edible offal.
In Europe, the highest levels of PFOS and PFOA were found in edible offal of wild animals, averaging 214 µg/kg and 5.5 µg/kg, respectively, and 14.12 µg/kg and 4.1 µg/kg in carp, respectively. PFNA and PFHxS are found less frequently and at lower concentrations in food. Not only animal foods may contain PFAS, but also plant foods, as they can be readily absorbed through the root. Thus, small amounts of PFAS can also be measured in fruits and vegetables, such as an average PFOS content of 0.027 µg/kg in fruits and fruit products.
In Austria, PFAS are investigated as part of the priority action "Environmental contaminants in food - monitoring". A total of 85 food samples were analyzed for the 4 PFASs PFOA, PFNA, PFHxS and PFOS by 2022. PFOS was found most frequently in the tested foods, in 26 food samples, followed by PFOA in 21 samples and PFNA in 12 samples. The average levels for PFOA, PFNA, PFHxS and PFOS in different food groups are shown in the table. The highest levels for PFOS were measured in bream at 2.57 µg/kg, followed by PFOA at 0.92 µg/kg in veal and PFHxS at 0.55 µg/kg in trout, turkey and pork.
Maximum levels for PFAS in drinking water
With the aim of determining the possible contamination of drinking water with PFAS throughout Austria, one focal action each was carried out at our Institute for Hydroanalytics in the years 2021 and 2022. A total of 582 drinking water samples were analyzed for 20 PFAS according to the EU Drinking Water Directive 2020/2184. Concentrations above the limit of quantification (LOD) were measured in a total of 213 samples (37%). Of these, 155 samples (27 %) had concentrations up to 10 ng/l. In 54 samples (9.3 %) the contents for the "sum of the 20 PFAS" were between 10.01 and 100 ng/l. 0.7 % of all samples (corresponding to four samples) showed a concentration above 100 ng/l with a maximum of 1,460 ng/l sum of the 20 PFAS.
From the group of perfluorinated carboxylic acids, perfluorobutanoic acid PFBA was most frequently quantified in concentrations above the limit of quantification (109 samples, 19%), followed by PFOA (101 samples, 17%) and perfluorohexanoic acid (60 samples, 10%). Perfluorononanoic acid to -dodecanoic acid was determined positive only occasionally (in three or five samples each). Perfluorotridecanoic acid was not detected above the limit of quantification in any sample. The highest measured concentrations of the individual substances were 233 ng/l for perfluoropentanoic acid, followed by 159 ng/l for PFHxA and 58 ng/l for PFBA.
From the group of perfluorinated sulfonic acids, perfluorobutanesulfonic acid PFBS was most frequently determined positive (99 samples, 17%), followed by PFOS (78 samples, 13%) and PFHxS (30 samples, 5%). Perfluoropentanesulfonic acid, perfluoroheptanesulfonic acid, perfluorononanesulfonic acid, and perfluorodecanesulfonic acid were determined positive only occasionally (in two to six samples each). Perfluorundecansulfonic acid to -tridecansulfonic acid were not detected above the limit of quantification in any sample. The highest measured concentrations of the individual substances were 770 ng/l for PFOS, followed by 303 ng/l for PFHxS and 63 ng/l for PFBS.
- Avoid consumption of offal, especially game such as wild boar liver.
- Breastfeeding recommendations should be followed based on currently available data
- If local drinking water is contaminated with PFAS, we recommend using uncontaminated other water for drinking and preparing infant formula
- Do not use contaminated drinking water for activities that could lead to ingestion of the water such as drinking, cooking, or preparing food and beverages
- Contaminated water can be used for personal hygiene (showering, bathing, shaving, brushing teeth...) as absorption through intact skin is negligible. The water can also be used for domestic purposes such as dishwashing, cleaning and laundry. This does not lead to an increase in PFAS uptake.
The European Food Safety Authority(EFSA) has already conducted several risk assessments on PFOS and PFOA. In 2008, a tolerable daily intake(TDI) for PFOS of 150 ng/kg bw/d and a TDI for PFOA of 1500 ng/kg bw/d were derived based on changes in blood lipids and thyroid hormones and liver toxicity in animal studies , respectively. In 2018, a re-evaluation was performed and a tolerable weekly intake(TWI) of 13 ng/kg bw/d for PFOS and 6 ng/kg bw/d for PFOA was established based on increasing blood cholesterol levels in human studies(EFSA 2018). Whereby it should be noted that elevated cholesterol levels are risk factors for cardiovascular disease, but are not directly considered as a disease.
In September 2020, EFSA published a reassessment on health risks from per- and polyfluorinated alkyl compounds in food. In this risk assessment, EFSA focused its attention on the sum of the following four PFASs, as they have similar substance properties and they have been most commonly detected in human blood: PFOA, PFOS, perfluorononanoic acid(PFNA) and perfluorohexanesulfonic acid(PFHxS). This risk assessment is based on epidemiological studies that have observed an association between the level of PFAS or the sum content of PFOA, PFOS, PFNA and PFHxS in the blood of children and reduced antibody formation after certain vaccinations, such as tetanus and diphtheria. Based on these studies, a tolerable weekly intake(TWI) for the sum of the four PFASs of 4.4 nanograms per kilogram of body weight per week was derived. This value indicates the weekly dose that is not expected to cause adverse health effects in humans with lifetime intake. This TWI also protects against all other observed effects that may be caused by PFAS, such as developmental toxic effects in the unborn child, such as delayed mammary gland development and lower birth weight, and the development of kidney and testicular cancer in adults.
The Agency for Toxic Substances and Disease Registry (ATSDR) has established 2021 Minimal Risk Levels (MRLs) for PFOA, PFOS, PFHxS, and PFNA for medium-term (15-364 days), oral intake. These MRLs are comparable to the tolerable daily intake (TDI) commonly used in Europe, except that they are defined for different time periods. Specifically, medium-term MRLs were derived for PFOA of 3 ng/kg bw/d, for PFOS of 2 ng/kg bw/d, for PFHxS of 20 ng/kg bw/d, and for PFNA of 3 ng/kg bw/d. These values for medium-term daily intake are substantially higher than the EFSA TWI value, which refers to a weekly lifetime intake.
WHO has proposed provisional guideline values (pGVs) with the aim of reducing human exposure to PFASs and thus reducing risk. In deriving the pGVs, global occurrence data, including co-occurrence of PFASs, available analytical methods, and drinking water treatment methods were considered. Individual pGVs of 0.1 μg/l each for PFOS and PFOA are proposed. However, these have not yet been published and are subject to change in the course of scientific discussion.
European Chemicals Agency(ECHA) hazard and label classification.
The hazard classification and labeling of per- and polyfluorinated alkyl compounds is done by the European Chemicals Agency(ECHA). The evaluation of the Committee for Risk Assessment(RAC) of ECHA is based solely on the hazardous properties of the substance and whether the substance can cause adverse effects. It does not take into account the risk or the extent to which people and the environment are exposed to the substance.
ECHA has classified PFOS, PFOA and PFNA as probably carcinogenic(CARC 2) and toxic to reproduction(Repr. 1B), meaning they can harm the unborn child and infants through breast milk. Additionally, PFNA is suspected to have an impact on fertility.
Due to its highly persistent and very bioaccumulative properties(i. e. the substance degrades very slowly in the environment and accumulates in organisms), PFHxS and its salts have been included in the list of substances of very high concern(SVHC) under Article 54e. According to the REACH Regulation, a substance of very high concern is defined as a substance with particularly hazardous properties that has serious effects on human health or the environment.
Once ECHA identifies a substance as such, it is entered in the list of substances subject to authorization under Annex XIV of the REACH Regulation. As an alternative to the authorization requirement, SVHC can also be included in Annex XVII of the REACH Regulation and thus be subject to restrictions.
Agency for Toxic Substances and Disease Registry (ATSDR), 2021: Toxicological Profile for Perfluoroalkyls. Released May 2021, Last Updated March 2020. Online verfügbar: https://www.atsdr.cdc.gov/toxprofiles/tp200.pdf
Deutsche Stillkommission 2021: Per- und polyfluorierte Alkylsubstanzen (PFAS) und Stillen: Nutzen-Risiken-Abwägungen. Stellungnahme vom 28. Januar 2021
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WHO, 2017 Drinking Water Parameter Cooperation Project Support to the revision of Annex I Council Directive 98/83/EC on the Quality of Water Intended for Human Consumption (Drinking Water Directive) Recommendations
Brüller et al. (2018). Occurrence of chemicals with known or suspected endocrine disrupting activity in drinking water, groundwater and surface water, Austria 2017/2018; Die Bodenkultur - Journal of Land Management, Food and Environment; 69 (3) : 155-173; ISSN: 0006-5471
Last updated: 28.08.2023