1. Contamination in Environment and Food
Due to the risks posed to human health by the exposure to PFASs, reliable data about the level of contamination of the environment and food matrices are required and several studies are already available
[1][2][3][4][5][6][7]. An updated overview is given in this section and then summarized in
Table 1 (environmental matrices) and
Table 2 (food and FCMs).
Table 1. Summary of relevant data from the literature for contamination of PFAS in environment.
Table 2. Summary of relevant data from the literature for contamination of PFAS in food and from FCMs.
2. Environmental Contamination
In order to estimate the risk posed by PFAS to human health, it is important to monitor the possible source to which humans can be exposed. In this respect, wastewater is known to play a significant role and several studies
[8][9] have studied the level of contamination of sludge from wastewater treatment plants (WWTPs) in Europe. In particular, Fredriksson et al.
[10] detected novel perfluoroalkyl sulfonamide-based (FASA) copolymers in WWTPs in Sweden. The study demonstrated that these copolymers come from both domestic and industrial sources. In New Zealand, Lenka et al.
[11] detected, in addition to 20 PFASs, ultrashort-chain perfluoropropionic acid (PFPrA) in urban waters, coming from two urban WWTPs.
A step forward is understanding the contribution of groundwaters. Several studies carried out in Europe and US addressed this point and showed high levels of contamination. In particular, 12 out of 29 PFASs were found in Sweden
[12] and 14 out of 24 in the Eastern United States
[13]. Given the large number of PFAS documented in commercial use and the environment, the PFASs examined here might not reflect the entire PFAS inventory in groundwater.
Also, crude oil, according to EPA
[14], needs to be tested due to its presence in the interface between soil and groundwater. Yao et al.
[15] proved that crude oil may be a significant source of PFAS contamination in the environment because they are applied in oil exploitation activity. PFCAs (27%) and p-perfluorousnonenoxybenzene sulphonate (OBS) (31%) made up the majority of the crude oil sample, while PFSAs (16%), ether-substituted polyfluoroalkyl (linear) sulphonic acids (OPFLSAs) (10%), 6:2 fluorotelomer sulfonamidoalkyl betaine (6:2 FTAB) (7%) and hydrogen-substituted polyfluoroalkyl (linear) carboxylic acids (HPFLCAs) (5%) made the rest of the samples. Their findings showed that certain new PFASs appeared in crude oil as a result of the use of chemical oil additives during the oil drilling process.
Ng et al.
[16] focused their study on rivers, another important possible source of contamination, looking for the occurrence of PFAS in the Danube River Basin. The researchers used both target and suspect screening (non-targeted) approaches that allowed them to detect a total of 82 PFAS, 72 of which were detected only by suspect screening. PFOS was the only compound found in all of the water and biota matrices studied. Five PFAS were detected only in influent wastewater samples and not in effluent wastewater samples, indicating that they were successfully removed during wastewater treatment.
Another approach for assessing contamination coming from the terrestrial environment is to use wild animals as indicators to monitor PFAS. Moretti et al.
[17] determined legacy and emerging poly- and per-fluoropolyethers in 28 wild boars using an HPLC-HRMS method. Boars were chosen because they are already confirmed to be suitable models to monitor PFAS contamination in the terrestrial environment
[18][19]. The boars come from Italy and the analysis was carried out by sampling the boars’ livers. The chloropolyfluoropolyeters carboxylates and their related dechlorinated congeners, HPFPECAs, were discovered for the first time in pooled liver from Italian wild boars. These PFASs might be used as an indicator for terrestrial food chains. This preliminary data shows that the panel of PFAS with toxicological significance should be expanded.
3. Contamination of Food and from Food Contact Materials
Global concern is spreading fast due to the high levels of PFAS detected in blood serum
[20][21][22][23]. The FDA’s Total Diet Study was one of the first studies monitoring PFAS in food in the United States. Genualdi et al.
[24] found out that three out of 167 samples were detected positive, but no foods had concentrations of PFAS above 150 ng/kg.
In this paragraph, an updated overview of the scientific research around PFAS contamination in relevant food and food related matrices is reported.
In the last decades many studies addressed the level of PFAS in drinking water
[25][26][27].
Liu et al.
[28] collected data on a total of 18 PFASs in 526 samples of drinking water from 66 Chinese cities. Cities that produce PTFE have significantly greater levels of PFOA in their drinking water than cities that do not (with significance explained by a
p < 0.05). The study showed that most Chinese cities have PFAS levels in drinking water that are higher than strict international guidelines and higher than Chinese health advisories.
Domingo et al.
[29] collected 30 samples at different stages of drinking water treatment in Catalonia and found relevant concentration of PFOS and PFOA.
Scher et al.
[30] analyzed the occurrence of PFAS in garden produce at homes to discover if soils with a history of contaminated drinking water could determine contamination for fruits and vegetables. The detection of PFBA and, with lower occurrence, PFPeA demonstrated the uptake of short-chained PFASs from soil to plants and confirmed that PFBA and PFPeA had the highest “foliage to root concentration factor” (defined as the concentration in foliage/concentration in the root). It was also established that PFBA concentrations strongly depended on the type of vegetable and on the water loading.
Babayev et al.
[31] aimed to understand the levels of PFAS in drinking water and blood serum for people in the southeast Alaska community. This pilot research confirmed that water samples nearby airport operations and fire training sites are strongly contaminated and found a positive correlation between PFAS concentrations in serum and well water. The most prevalent substances were PFOS, PFOA, PFHxS, and PFHxA.
Gloria B. Post
[32] published a mini-review on the Environmental Health Perspectives (EHP) about the PFAS levels in breast milk in the US and Canada populations. The researcher confirmed that it will be necessary to take preventive actions to protect breastfeeding mothers from exposure to PFAS in order to reduce their quantities in breast milk in the general population. Han et al.
[33] looked for 30 PFAS in 100 pooled human breast milk samples during the 2017–2020 National Human Milk Survey to characterize the exposure risks of legacy and emerging PFAS in perinatal women and their children in China. The findings showed that L-PFOA, L-PFOS, and 6:2 Cl-PFESA were the three most common PFAS found in Chinese human milk.
Giari et al.
[34] studied PFAS levels in fish species providing a significant information on the level of contamination of fish in the Po River, Italy. Prevalently were detected PFOS, PFDA and PFUnDA, while GenX and C6O4 were not detected. For the first time this study focused on the PFAS partitioning in a parasite-fish system obtaining that the infection state did not significantly alter the accumulation of PFAS in fish.
More than 500 samples of fish filets were characterized by Barbo et al.
[35] in the US from 2013 to 2015 as part of the US EPA’s monitoring programs. The study demonstrated that almost all fish in American rivers, streams, and the Great Lakes were contaminated by significant levels of PFAS, primarily PFOS, whereas seafood purchased at grocery stores has significantly lower levels of PFAS. Other studies, such as Kumar et al.
[36], made progress in detecting PFAS contamination by looking for fluorinated compounds in fish samples in the Baltic Sea and Finnish lakes, and PFOS was found in all the 1134 fishes analyzed, and also long-chain PFCAs were frequently detected. The monitoring of PFOS levels over the last decades do not show any decrease, so this demonstrates that no effective actions have been taken. In the Czech Republic, Semerád et al.
[37] confirmed contamination in freshwater fishes. In particular, long-chain PFASs were detected at a relevant concentration, with short-chain PFASs and GenX measured at relatively low levels. A study focused on fish filet samples
[38] showed that from 2014 and 2019 a decrease of PFAS occurred, while PFOS increased. Hoa et al.
[39] deepened the study on fish by investigating distribution of PFAS contamination in the different tissues. The fish blood samples were found to be contaminated by 17 PFAS, with concentrations from 5.2 ng/mL to 29 ng/mL. In addition, the concentrations were substantially higher in liver samples than in muscle samples. In general, the study demonstrated that PFAS have unique distribution profiles depending on the species, tissue, and location. Rüdel et al.
[40] derived a filet-to-whole fish conversion factor to assess potential risks posed by the consumption of fish filet.
PFAS contamination in eggs has been studied as well due to their greasy nature
[41][42]. Miller et al.
[43] investigating temporal trends of PFAS in eggs of different species. Among all PFAS, PFOS was found to be present in the highest concentration, even if with a decreasing trend over time probably due their industrial phase out in the last decades. On the contrary, long chain PFAS such as perfluorotridecanoic acid (PFTrDA) and perfluoroundecanoic acid (PFUdA) were found to increase. These results were confirmed by Glória Pereira et al.
[44], during a monitoring over 35 years in eggs of the northern gannet in UK.
Investigations by Granby et al.
[45] of the Technical University of Denmark (DTU) National Food Institute unequivocally show that the PFAS entered the eggs through fish meal in the chicken diet. Hence, substituting a non-contaminated feed component might substantially lower the amount of PFAS in the eggs within a few weeks.
Androulakakis et al.
[46] studied freshwater and terrestrial top predators from Northern Europe. The majority of apex predators (AP) and their prey were found to be contaminated, and, in particular the three perfluoroalkylphosphinic acids were detected in all the samples. The study demonstrated a strong correlation between the geographic origin of the specimens and the quantities of PFAS in AP, with samples taken from urban and agricultural regions being significantly more polluted than those taken from pristine or semi-pristine places.
The migration of PFAS from Food Contact Materials (FCMs) is considered to be a relevant source of contamination. According to Galbiati et al.
[47], some substances in the group of PFASs used in the FCM production have been classified as endocrine-disrupting chemicals (EDCs), therefore it is important to investigate their possible migration into foods. Lerch et al.
[48] conducted migration tests on paper FCMs treated with PFAS for understanding their behavior at high temperature applications, and it was found that PFAS migration to real foods contributes significantly to tolerable weekly intake. Minet et al.
[49] studied the use and release of PFASs in FCMs in Canada and the US and showed that FCM containing minimal concentration of PFAS can nonetheless contaminate the entire waste stream. In Canada, Schwartz-Narbonne et al.
[50] tested fast food packaging for PFAS contamination by comparing compostable bowls to single-use plastic bowls. Despite the fact that compostable bowls are promoted as “green” alternatives to plastic bowls, they have been positively tested for PFAS contamination sources and therefore appear to be a regrettable alternative to single-use bowls.
Testing food simulants and leakage of non-intentionally added substances (NIAS) by FCMs is not the only way to estimate the level of contamination of PFAS related to food packaging migration. It is also important to investigate the exposure of consumers
[51][52][53][54][55]. Susmann et al.
[56], for example, studied the dietary habits of the US population, monitoring the exposure to PFASs also through food packaging. The results showed that popcorn consumption is associated with significantly higher levels of PFOA, PFNA, PFDA, and PFOS in serum. This correlation was not detected in other types of foods, e.g., pizza. That outcome could be accounted for as an effect of the migration from microwave popcorn packaging.
The fact that PFAS can contaminate humans is demonstrated by studies addressing the measurement of PFAS levels in blood serum. The work of Richterová et al.
[57] was the first research to use standardized, consistent, and quality-controlled PFAS exposure data from Europe. This research was carried out as a European Human Biomonitoring Initiative (HBM4EU) aligned study. A total of 1957 children and teenagers from Sweden, Norway, Slovakia, Spain, Slovenia, Greece, France, Germany, and Belgium were tested. Almost all subjects tested positive for PFOS, PFOA, PFNA, and PFHxS. Teenagers in the North and West of Europe have much higher PFAS values than those in the South and East. The eating of fish and shellfish was linked to greater PFAS concentrations, while consuming eggs was linked to increased concentrations of PFOS and PFNA. These findings offer details on possible PFAS exposure sources for focused PFAS in food monitoring.
Monitoring PFAS in food and environment is critical to understanding and managing potential health and environmental impacts. Accurate and reliable measurements of levels of PFAS in our soils, water, and foods will ensure the development of effective action in preventing and/or mitigating the possible risk related to PFAS.
According to recent studies, several food matrices, including those intended for infants and children, have been found to be positive to PFAS contamination at levels that are strongly dependent on the geographical area (e.g., proximity to industrial areas). In addition, it is concerning to see how high PFAS levels are in food contact materials. We need to take steps to reduce our exposure by using materials that are free from this contaminant. The health risks associated with the long-term consumption of PFAS are still not fully understood, so it is important to take proactive steps to reduce our exposure whenever possible, as phasing out PFAS from production of FCM.