Transfer of Per- and Polyfluoroalkyl Substances (PFAS) from Feed into the Eggs of Laying Hens. Part 2: Toxicokinetic Results Including the Role of Precursors

Perfluoroalkyl substances in the meat of Polish farm animals and game - Occurrence, profiles and dietary intake

Meat from farm animals (pigs, cattle and poultry) and game (wild boar and deer) was analysed in terms of thirteen perfluoroalkyl substances (PFASs). Wild boar muscle tissue was statistically significantly more contaminated than muscle tissue from other animals, and the species order of the lower-bound (LB) sum of four (∑4) PFAS (perfluorooctanesulfonic acid (PFOS), perfluorooctanoic acid, perfluorononanoic acid and perfluorohexanesulfonic acid) concentrations was wild boar > cattle > deer > pigs > poultry. None of the samples exceeded the maximum levels set by Commission Regulation (EU) 2023/915. Linear PFOS was the most frequently detected compound (in 21 % of all samples analysed and 100 % of wild boar samples), reaching its highest concentration of 1.87 μg/kg wet weight in wild boar. Dietary intake was estimated on the basis of the average per-serving consumption of pork, beef and poultry, and in the absence of such data for game, a 100 g portion was used for the calculation. Mean LB∑4 PFAS concentrations led to intakes between 0.000 and 1.75 ng/kg body weight (BW) for children and 0.000 and 0.91 ng/kg BW for adults. The potential risk to consumers was assessed in relation to the tolerable weekly intake (TWI) of 4.4 ng/kg BW established by the European Food Safety Authority in 2020. Exposure associated with the consumption of poultry, pork, beef and venison was negligible, being only <1 % of the TWI for children and adults; higher exposure was found to associate with the consumption of wild boar, being 63 % and 21 % of the TWI for children and adults, respectively. The findings of this research suggest that the intake of PFASs through the consumption of meat from Polish livestock and deer is unlikely to be a health concern. However, frequent consumption of wild boar meat could be a significant source of PFASs.

Chickens' eggs and the livers of farm animals as sources of perfluoroalkyl substances

Introduction

This study focuses on perfluoroalkyl substance (PFAS) content in chickens' eggs and the livers of farm animals.

Material and Methods

Chickens' eggs (n = 25) and the livers of cows (n = 10), chickens (n = 7) and horses (n = 3) were collected from various regions of Poland. Samples were analysed using the isotope dilution technique with liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS).

Results

The mean lower bound (LB) sum of four PFAS (∑4 PFAS) concentrations (perfluorooctanesulfonic acid (PFOS), perfluorooctanoic acid (PFOA), perfluorononanoic acid (PFNA) and perfluorohexanesulfonic acid (PFHxS)) were the highest in cows' livers (0.52 μg/kg) and much lower in chickens' (0.17 μg/kg) and horses' livers (0.13 μg/kg) and chickens' eggs (0.096 μg/kg). The ratio of ∑4 PFASs to the limits set by Commission Regulation (EU) 2023/915 was <7% for liver and <6% for eggs. Linear PFOS was the compound with the highest detection frequency (8% in eggs and 48% in all livers). In cows' livers it was detected in 80% of samples. The estimated exposure to LB ∑4 PFASs via consumption of liver tissue from farm animals (assuming 50 g and 100 g portions) was <52% of the tolerable weekly intake (TWI) for children and <17% of the TWI for adults. Dietary intake via the average portion of three eggs led to low exposure of <15% for children and <5% for adults.

Conclusion

Neither eggs nor the livers of chickens or horses as analysed in this study are significant sources of PFASs, while cows' livers might contribute significantly to a child's overall dietary intake. Further investigation of PFOS in farm animal livers should be conducted.

Dynamic spatiotemporal changes of per- and polyfluoroalkyl substances (PFAS) in soil and eggs of private gardens at different distances from a fluorochemical plant

Homegrown food serves as an important human exposure source of per- and polyfluoroalkyl substances (PFAS), yet little is known about their spatiotemporal distribution within and among private gardens. This knowledge is essential for more accurate site-specific risk assessment, identification of new sources and evaluating the effectiveness of regulations. The present study evaluated spatiotemporal changes of legacy and emerging PFAS in surface soil from vegetable gardens (N = 78) and chicken enclosures (N = 102), as well as in homegrown eggs (N = 134) of private gardens, across the Province of Antwerp (Belgium). Hereby, the potential influence of the wind orientation and distance towards a major fluorochemical plant was examined. The ∑short-chain PFAS and precursor concentrations were higher in vegetable garden soil (8.68 ng/g dry weight (dw)) compared to chicken enclosure soil (4.43 ng/g dw) and homegrown eggs (0.77 ng/g wet weight (ww)), while long-chain sulfonates and C11-14 carboxylates showed the opposite trend. Short-term (2018/2019-2022) changes were mostly absent in vegetable garden soil, while changes in chicken enclosure soils oriented S-SW nearby (<4 km) the fluorochemical plant were characterized by a local, high-concentration plume. Moreover, soil from chicken enclosures oriented SE and remotely from the plant site was characterized by a widespread, diffuse but relatively low-concentration plume. Long-term data (2010-2022) suggest that phaseout and regulatory measures have been effective, as PFOS concentrations nearby the fluorochemical plant in soil and eggs have declined from 25.8 to 2.86 ng/g dw and from 528 to 39.4 ng/g ww, respectively. However, PFOS and PFOA concentrations have remained largely stable within this timeframe in gardens remotely from the plant site, warranting further rapid regulation and remediation measures. Future monitoring efforts are needed to allow long-term comparison for multiple PFAS and better distinction from potential confounding variables, such as variable emission outputs and variability in wind patterns.

Dietary exposure to per- and polyfluoroalkyl substances: Potential health impacts on human liver

Per- and polyfluoroalkyl substances (PFAS), dubbed "forever chemicals", are widely present in the environment. Environmental contamination and food contact substances are the main sources of PFAS in food, increasing the risk of human dietary exposure. Numerous epidemiological studies have established the link between dietary exposure to PFAS and liver disease. Correspondingly, PFAS induced-hepatotoxicity (e.g., hepatomegaly, cell viability, inflammation, oxidative stress, bile acid metabolism dysregulation and glycolipid metabolism disorder) observed from in vitro models and in vivo rodent studies have been extensively reported. In this review, the pertinent literature of the last 5 years from the Web of Science database was researched. This study summarized the source and fate of PFAS, and reviewed the occurrence of PFAS in food system (natural and processed food). Subsequently, the characteristics of human dietary exposure PFAS (population characteristics, distribution trend, absorption and distribution) were mentioned. Additionally, epidemiologic evidence linking PFAS exposure and liver disease was alluded, and the PFAS-induced hepatotoxicity observed from in vitro models and in vivo rodent studies was comprehensively reviewed. Lastly, we highlighted several critical knowledge gaps and proposed future research directions. This review aims to raise public awareness about food PFAS contamination and its potential risks to human liver health.

Per- and poly-fluoroalkyl substances in commercial organic eggs via fishmeal in feed

Chicken eggs can be a significant source of human PFAS exposure. A survey of PFAS in commercial eggs from larger farms across Denmark showed the absence or low contents of PFAS in free-range and barn eggs. However, organic eggs from eight farms collected in September 2022 had a similar profile of nine PFASs with a predominance of odd over even carbon length PFCAs. Farm 11-13 e.g. had egg yolk ng/g concentrations of PFOA 0.07 ± 0.02; PFNA 0.37 ± 0.04; PFDA 0.13 ± 0.00; PFUnDA 0.22 ± 0.04; PFDoDA 0.06 ± 0.02; PFTrDA 0.15 ± 0.04; PFTeDA 0.02 ± 0.02; PFHxS 0.10 ± 0.04; PFOS 2.62 ± 0.11. Normalised to PFOS, the relative sum of other PFAS showed no difference between the eight organic egg samples, but significant differences between mean individual PFASs (p = 1.4E-25), reflecting a similar profile. The PFAS found in two fishmeal samples with the same origin as the fishmeal used for the organic feed production, could account for the contents in the eggs via estimated transfer from the feed. Furthermore, the estimated transfer from concentration in feed to concentration in egg increased with the carbon length of the PFCA. Exposure (95th percentile) of ∑4PFAS (PFOA, PFNA, PFHxS, PFOS) solely from consumption of 311 g ∼ 5-6 organic eggs/week was for children 4-9 years 10.4 ng/kg bw, i.e. a significant exceedance of the tolerable weekly intake of 4.4 ng/kg bw established by the European Food Safety Authority. Based on the PFAS exposures from organic egg consumption, the organic egg producers decided voluntarily to cease adding fishmeal to the feed. Since the feed-to-egg half-lives are ≤1 week for PFOA, PFOS, and PFHxS, the removal of fishmeal as a feed ingredient should eliminate PFAS after 1-2 months. This was demonstrated in analyses of ten organic egg samples collected by the authorities without PFAS in eight and with 0.1 and 0.4 ng/g ∑4PFAS in two samples.

Bioaccumulation, tissue distributions, and maternal transfer of perfluoroalkyl carboxylates (PFCAs) in laying hens

Laying hens were exposed to feeds spiked with a series of perfluoroalkyl carboxylates (PFCAs) ranging from perfluorobutanoic acid (C4) to perfluorooctadecanoic acid (C18) to investigate their bioaccumulation, tissue distribution, and maternal transfer. We found that PFCAs with longer carbon chains (>8) were more efficiently absorbed in the gastrointestinal tract than those with shorter chains (≤8), and that the rate of depuration varied inversely with the carbon chain length in a U-shaped pattern. Moreover, bioaccumulation potential increased with increasing carbon-chain length, except for C4. Distinct affinities were observed for specific carbon-chain PFCAs across various tissues, evident from their differential accumulation during both uptake and depuration phases. Specifically, C9 showed a higher affinity for serum and liver, C12 was more prevalent in yolk, C14 was notably abundant in the brain, and C18 was predominant in other tissues. Furthermore, the egg-maternal ratio (EMR) increased with increasing carbon-chain length from C7 to C11 and reached a plateau phase for C12 to C18. Our study also confirmed the key role of phospholipids in the tissue distribution and maternal transfer of long-chain PFCAs. This study sheds light on the interaction between PFCAs and biological tissues and reveals the toxicokinetic factors that influence the bioaccumulation of PFCAs. Further research is needed to identify the specific proteins or components that mediate the tissue-specific affinity for different carbon-chain lengths of PFCAs.

The sources and bioaccumulation of per- and polyfluoroalkyl substances in animal-derived foods and the potential risk of dietary intake

Per- and polyfluoroalkyl substances (PFAS) have attracted increasing attention due to their environmental persistence and potential toxicity. Diet is one of the main routes of human exposure to PFAS, particularly through the consumption of animal-derived foods (e.g., aquatic products, livestock and poultry, and products derived from them). This review summarizes the source, bioaccumulation, and distribution of PFAS in animal-derived foods and key influential factors. In most environmental media, perfluorooctanoic acid and perfluorooctane sulfonate are the dominant PFAS, with the levels of short-chain PFAS such as perfluorobutyric acid and perfluorohexane sulfonate surpassing them in some watersheds and coastal areas. The presence of PFAS in environmental media is mainly influenced by suspended particulate matter, microbial communities as well as temporal and spatial factors, such as season and location. Linear PFAS with long carbon chains (C ≥ 7) and sulfonic groups tend to accumulate in organisms and contribute significantly to the contamination of animal-derived foods. Furthermore, PFAS, due to their protein affinity, are prone to accumulate in the blood and protein-rich tissues such as the liver and kidney. Species differences in PFAS bioaccumulation are determined by diet, variances in protein content in the blood and tissues and species-specific activity of transport proteins. Carnivorous fish usually show higher PFAS accumulation than omnivorous fish. Poultry typically metabolize PFAS more rapidly than mammals. PFAS exposures in the processing of animal-derived foods are also attributable to the migration of PFAS from food contact materials, especially those in higher-fat content foods. The human health risk assessment of PFAS exposure from animal-derived foods suggests that frequent consumption of aquatic products potentially engender greater risks to women and minors than to adult males. The information and perspectives from this review would help to further identify the toxicity and migration mechanism of PFAS in animal-derived foods and provide information for food safety management.

Development and application of an interactive generic physiologically based pharmacokinetic (igPBPK) model for adult beef cattle and lactating dairy cows to estimate tissue distribution and edible tissue and milk withdrawal intervals for per- and polyfluoroalkyl substances (PFAS)

Humans can be exposed to per- and polyfluoroalkyl substances (PFAS) through dietary intake from milk and edible tissues from food animals. This study developed a physiologically based pharmacokinetic (PBPK) model to predict tissue and milk residues and estimate withdrawal intervals (WDIs) for multiple PFAS including PFOA, PFOS and PFHxS in beef cattle and lactating dairy cows. Results showed that model predictions were mostly within a two-fold factor of experimental data for plasma, tissues, and milk with an estimated coefficient of determination (R2) of >0.95. The predicted muscle WDIs for beef cattle were <1 day for PFOA, 449 days for PFOS, and 69 days for PFHxS, while the predicted milk WDIs in dairy cows were <1 day for PFOA, 1345 days for PFOS, and zero day for PFHxS following a high environmental exposure scenario (e.g., 49.3, 193, and 161 ng/kg/day for PFOA, PFOS, and PFHxS, respectively, for beef cattle for 2 years). The model was converted to a web-based interactive generic PBPK (igPBPK) platform to provide a user-friendly dashboard for predictions of tissue and milk WDIs for PFAS in cattle. This model serves as a foundation for extrapolation to other PFAS compounds to improve safety assessment of cattle-derived food products.

Incidence of Perfluoroalkyl Substances in Commercial Eggs and Their Impact on Consumer's Safety

Eggs play an important role in a balanced diet; however, the European Food Safety Authority (EFSA) recognizes eggs as a major source of poly and per-fluoroalkyl substances (PFASs). In this study, the presence of PFASs was analysed in eggs produced by hens from Northern Italian regions, a PFASs-contaminated area. Sixty-five samples were analysed by high-performance liquid chromatography coupled with high-resolution mass spectrometry. The greatest presence of PFASs was found in eggs from Veneto and Emilia Romagna, and the most detected PFASs were perfluorobutanoic acid (PFBA) and perfluorooctanesulfonic acid (PFOS) (mean concentrations 0.30 ± 0.15 and 0.05 ± 0.00 ng g-1). Considering the most recent updates for the sum of the main four PFASs, the highest concentration found in the analysed samples was 0.05 ng g-1, well below the maximum limit set by the European Union. The PFAS intake evaluation confirmed that egg consumption does not represent a risk for Italian consumers.

Dynamic exposure and body burden models for per- and polyfluoroalkyl substances (PFAS) enable management of food safety risks in cattle

With increasing global focus on planetary boundaries, food safety and quality, the presence of per- and polyfluoroalkyl substances (PFAS) in the food chain presents a challenge for the sustainable production and supply of quality assured food. Consumption of food is the primary PFAS exposure route for the general population. At contaminated sites, PFAS have been reported in a range of agricultural commodities including cattle. Consumer exposure assessments are complicated by the lack of validated modelling approaches to estimate PFAS bioaccumulation in cattle. Previous studies have shown that PFAS bioaccumulation in livestock is influenced by environmental, spatial and temporal factors that necessitate a dynamic modelling approach. This work presents an integrated exposure and population toxicokinetic (PopTK) model for cattle that estimates serum and tissue concentrations of PFAS over time. Daily exposures were estimated from intakes of water, pasture, and soil, and considered animal growth, seasonal variability (pasture moisture content and temperature) and variable PFAS concentrations across paddocks. Modelled serum and tissue estimates were validated against monitoring data from Australian and Swedish cattle farms. The models were also used to develop and test practical management options for reducing PFAS exposure and to prioritise remediation for farms. Model outputs for exposure management scenarios (testing cattle rotation and targeted supplementation of feed and water) showed potential for marked reductions in consumer exposures from cattle produce.

Spatio-temporal trends in livestock exposure to per- and polyfluoroalkyl substances (PFAS) inform risk assessment and management measures

The migration of per- and polyfluoroalkyl substances (PFAS) onto agricultural properties has resulted in the accumulation of PFAS in livestock. The environmental determinants of PFAS accumulation in livestock from the grazing environment are poorly understood, resulting in limited capacity to manage livestock exposure and subsequent transfer of PFAS through the food chain. Analytical- (n = 978 samples of soil, water, pasture, and serum matrices), farm management/practice- and livestock physiology data were collated and interrogated from environmental PFAS investigations across ten farms, from four agro-ecological regions of Victoria (Australia). Statistical analysis identified perfluorooctane sulfonate (PFOS) and perfluorohexane sulfonate (PFHxS) as key analytes of concern for livestock bioaccumulation. PFOS and PFHxS concentrations in livestock drinking water were positively correlated with serum concentrations while other intake pathways (pasture and soil) had weaker correlations. Seasonal trends in PFAS body burden (serum concentrations) were identified and suggested to be linked to seasonal grazing behaviours and physiological water requirements. The data showed for the first time that livestock exposure to PFAS is dynamic and with relatively short elimination half-lives, there is opportunity for exposure management. Meat from cattle, grazed on PFAS impacted sites, may exceed health-based guideline values for PFAS, especially for markets with low limits (like the European Commission Maximum Limits or EC MLs). This study found that sites with mean livestock drinking water concentrations as low as 0.003 μg PFOS/L may exceed the EC ML for PFOS in cattle meat. Risk assessment can be used to prioritise site cleanup and development of management plans to reduce PFAS body burden by considering timing of stock rotation and/or supplementation of primary exposure sources.

Occurrence and implications of per and polyfluoroalkyl substances in animal feeds used in laboratory toxicity testing

The exceptional thermal and chemical stability and the amphiphilicity of per- and polyfluoroalkyl substances (PFAS) have resulted in widespread use and subsequent contamination in environmental media and biota. Concerns surrounding toxicity have led to numerous animal-based toxicity studies. Due to the ubiquity of PFAS and the low parts per trillion (ppt) health advisory levels for drinking water, several contamination elimination protocols have been implemented. In addition, it is urgently necessary to perform low-dose experiments, but due to unknown pathways for entry of unwanted PFAS, low-dose studies are extremely challenging to conduct. However, animal feed sources are a likely route that could introduce unwanted PFAS into experiments, yet investigations of PFAS in common animal feeds are lacking. Here, we report the examination of PFAS levels in eighteen different animal feeds, representing a range of diets fed to diverse taxa. We evaluated whether PFAS levels in feeds were correlated with ingredient composition (plant versus animal-based) or dietary habits of lab animals (amphibian, fish, invertebrate, mammal). PFOS, PFHxS, PFOA, and short-chain perfluoroalkyl carboxylic acids had the highest detection levels and frequencies across all samples. Different food ingredients led to different PFAS profiles. No meaningful levels of PFAS precursors were detected. We demonstrate that PFAS contamination in animal feed is pervasive. Reducing food-sourced PFAS is a critical, albeit challenging task to improve interpretability of in vivo exposures.

Home-produced eggs: An important human exposure pathway of perfluoroalkylated substances (PFAS)

Humans are generally exposed to per- and polyfluoroalkyl substances (PFAS) through their diet. Whilst plenty of data are available on commercial food products, little information exists on the contribution of self-cultivated food, such as home-produced eggs (HPE), to the dietary PFAS intake in humans. The prevalence of 17 legacy and emerging PFAS in HPE (N = 70) from free-ranging laying hens was examined at 35 private gardens, situated within a 10 km radius from a fluorochemical plant in Antwerp (Belgium). Potential influences from housing conditions (feed type and number of individuals) and age of the chickens on the egg concentrations was examined, and possible human health risks were evaluated. Perfluorooctane sulfonic acid (PFOS) and perfluorooctanoic acid (PFOA) were detected in all samples. PFOS was the dominant compound and concentrations (range: 0.13-241 ng/g wet weight) steeply decreased with distance from the fluorochemical plant, while there was no clear distance trend for other PFAS. Laying hens receiving an obligate diet of kitchen leftovers, exhibited higher PFOS and PFOA concentrations in their eggs than hens feeding only on commercial food, suggesting that garden produce may be a relevant exposure pathway to both chickens and humans. The age of laying hens affected egg PFAS concentrations, with younger hens exhibiting significantly higher egg PFOA concentrations. Based on a modest human consumption scenario of two eggs per week, the European health guideline was exceeded in ≥67% of the locations for all age classes, both nearby and further away (till 10 km) from the plant site. These results indicate that PFAS exposure via HPE causes potential human health risks. Extensive analysis in other self-cultivated food items on a larger spatial scale is highly recommended, taking into account potential factors that may affect PFAS bioavailability to garden produce.

Toxicokinetic Modeling of the Transfer of Non-Dioxin-like Polychlorinated Biphenyls (ndl-PCBs) from Feed and Soil into Laying Hens and Their Eggs

Non-dioxin-like polychlorinated biphenyls (ndl-PCBs) are a subclass of persistent bioaccumulative pollutants able to enter the food chain. Toxicokinetic models for the transfer of the six ndl-PCB congeners (PCBs 28, 52, 101, 138, 153, and 180) from contaminated feed and soil into chicken eggs and meat are presented. Three independent controlled feeding study datasets were used to estimate the model parameters and four studies for evaluating the model performance. The yolk deposition of ndl-PCBs is modeled in a novel way that mimics the physiology of yolk growth and development, resulting in improved prediction of the experimental data without introducing an ad hoc time delay between ovulation and oviposition. Using the models, the highest level of 2.4 μg/kg dry matter (DM) was calculated for the sum of ndl-PCBs in laying hen feed to ensure that the current maximum levels in meat and eggs (40 ng/g fat) will not be exceeded. It is also shown how this highest level in feed should be adapted in case soil, in addition to feed, is also a source of ndl-PCBs for free-range chickens.

Perfluoroalkyl substances in hen eggs from different types of husbandry

Poultry eggs from cage, ecological and free range production were analyzed in terms of perfluoroalkyl substances (PFASs). Taking into account all fourteen analyzed compounds, perfluorobutanoic acid (PFBA) reach the highest concentrations (mean 0.23, 0.24, 0.27 μg/kg wet weight (w.w) for organic, cage and free range eggs respectively. Taking into account the lower bound sum of four PFASs: PFOS, PFOA, PFNA, PFHxS which according to EFSA, made up half of the lower bound exposure to PFASs, organic eggs were the most contaminated (0.10 μg/kg wet weight) followed by free range (0.04 μg/kg wet weight) and battery cage (0.00 μg/kg wet weight). The percentage share in the lower bound concentration indicates the dominant role of PFOS (37-100%). Linear PFOS accounted for 71-92% of the sum of linear and branched PFOS. Estimates of PFOS, PFOA, PFNA, PFHxS intake via eggs based lower-bound concentrations were 0.00-0.65 ng/kg b. w for children and 0.00-0.21 ng/kg b. w for adults which corresponds to 0-15% of the tolerable weekly intake (TWI) and 0-5% TWI for children and adult respectively.

A pilot evaluation on the toxicokinetics and bioaccumulation of polychlorinated naphthalenes in laying hens

Knowledge of the transfer features of polychlorinated naphthalenes (PCNs), a class of emerging persistent organic pollutants (POPs), is still lacking concerning the environment-feed-food transfer chain of farm animals. We conducted a controlled feeding experiment with laying hens fed fly ash-contaminated diets to investigate the toxicokinetics and bioaccumulation of PCNs (tri- to octa-CNs) in the hen eggs and tissues. The eggs showed increasing PCNs levels after 14 days of oral exposure, which gradually decreased during the 28-day depuration period but still exceeded the initial levels. The apparent one-compartment half-life of ∑₆₃PCNs in the eggs was 28.9 days, which was comparable to those of other dioxin-like compounds. The uptake and depuration rates of PCN congeners in the eggs were 0.002-0.010 and 0.016-0.079 days^-1 in eggs, respectively. The depuration rates were decreased with the n-octanol/water partition coefficients (logK_OW), indicating that the eggs retained more lipophilic congeners, whereas the uptake rates increased with the logK_OW, indicating the faster deposition of the more lipophilic PCNs in eggs during the exposure period. The transfer rates of PCN congeners ranged from 0.27%-23.0%, indicating the transfer potential of PCNs from feed to eggs. Additionally, the PCN distribution in the laying hens at the end of the exposure showed tissue-specific accumulation, with the high levels of PCNs in the liver, spleen, and ovum. Positive correlations between the transfer factors (C_tissue/C_feed) and the logK_OW suggested that more lipophilic PCN congeners tended to accumulate in the tissues. After quantitatively assessing the feed-to-food transfer of PCNs in laying hens, our results highlight the risk of exposure to PCNs in the food supply chain.

Degradation and Plant Transfer Rates of Seven Fluorotelomer Precursors to Perfluoroalkyl Acids and F-53B in a Soil-Plant System with Maize (Zea mays L.)

Fluorotelomer precursors in soil constitute a reservoir for perfluoroalkyl acids (PFAAs) in the environment. In the present study, precursor degradation and transfer rates of seven fluorotelomer precursors and F-53B (chlorinated polyfluoroalkyl ether sulfonates) were investigated in pot experiments with maize plants (Zea mays L.). The degradation of fluorotelomer precursors to perfluoroalkyl carboxylic acids (PFCAs) and their uptake spectra corresponded to those of fluorotelomer alcohol (FTOH) in terms of the number of perfluorinated carbon atoms. Short-chain PFCAs were translocated into the shoots (in descending order perfluoropentanoic, perfluorobutanoic, and perfluorohexanoic acid), whereas long-chain PFCAs mainly remained in the soil. In particular, fluorotelomer phosphate diesters (diPAPs) were retained in the soil and showed the highest degradation potential including evidence of α-oxidative processes. F-53B did not degrade to PFAAs and its constituents were mainly detected in the roots with minor uptake into the shoots. The results demonstrate the important role of precursors as an entry pathway for PFCAs into the food chain.

Food, Beverage, and Feedstock Processing Facility Wastewater: a Unique and Underappreciated Source of Contaminants to U.S. Streams

Process wastewaters from food, beverage, and feedstock facilities, although regulated, are an under-investigated environmental contaminant source. Food process wastewaters (FPWWs) from 23 facilities in 17 U.S. states were sampled and documented for a plethora of chemical and microbial contaminants. Of the 576 analyzed organics, 184 (32%) were detected at least once, with concentrations as large as 143 μg L^-1 (6:2 fluorotelomer sulfonic acid), and as many as 47 were detected in a single FPWW sample. Cumulative per/polyfluoroalkyl substance concentrations up to 185 μg L^-1 and large pesticide transformation product concentrations (e.g., methomyl oxime, 40 μg L^-1; clothianidin TMG, 2.02 μg L^-1) were observed. Despite 48% of FPWW undergoing disinfection treatment prior to discharge, bacteria resistant to third-generation antibiotics were found in each facility type, and multiple bacterial groups were detected in all samples, including total coliforms. The exposure-activity ratios and toxicity quotients exceeded 1.0 in 13 and 22% of samples, respectively, indicating potential biological effects and toxicity to vertebrates and invertebrates associated with the discharge of FPWW. Organic contaminant profiles of FPWW differed from previously reported contaminant profiles of municipal effluents and urban storm water, indicating that FPWW is another important source of chemical and microbial contaminant mixtures discharged into receiving surface waters.