Residue Distribution and Daily Exposure of Per- and Polyfluoroalkyl Substances in Indica and Japonica Rice

Drivers of change behind the spatial distribution and fate of typical trace organic pollutants in fresh waste leachate across China

There have been growing concerns regarding the health and environmental impacts of trace organic pollutants (TOPs). However, fresh leachate from municipal solid waste (MSW) has been overlooked as a potential reservoir of TOPs. Therefore, we investigated 90 legacy and emerging TOPs in fresh leachate from 14 provinces and municipalities in China. Additionally, the fate and final discharge impacts of TOPs in 14 leachate treatment systems were analyzed. The results revealed that the detection rate of 90 TOPs was over 50 % in all samples. Notably, polychlorinated biphenyls, banned for 40 years, were frequently detected in fresh leachate. The concentration of pseudo-persistent TOPs (105-107 ng/L) is significantly higher than that of persistent TOPs (102-104 ng/L). Spatial distribution patterns of TOPs in fresh leachate suggest that economy, population, climate, and policies impact TOPs discharge from MSW. For example, economically developed and densely populated areas displayed higher TOPs concentrations, whereas warmer climates facilitate TOPs leaching from MSW. We confirmed that waste classification policies were a key driver of the decline in multiple TOPs in leachate. Mass balance analysis shows that the final effluent and sludge from current dominant leachate treatment systems contain refractory TOPs, especially perfluoroalkyl acids, which must be prioritized for control. This paper was the first comprehensive investigation of multiple TOPs in fresh leachate at a large geographic scale. The factors affecting the occurrence, spatial distribution, and fate of TOPs in fresh leachate were revealed. It provides a valuable reference for the establishment of policies for the management of TOPs in MSW and the associated leachate.

Perfluoroalkyl substances and metabolic syndrome: A cross-sectional study using data from the US national health and nutrition examination survey

Background

Epidemiological studies linking metabolic syndrome (MetS) and exposure to perfluoroalkyl substances (PFASs) are limited, and the observations gleaned thus far are inconclusive. The study was performed to explore the association of serum PFASs both singly and in a mixed manner with MetS, and meanwhile to examine whether this association was mediated by serum albumin in a US national population.

Methods

Total 8108 participants from the National Health and Nutrition Examination Survey, 2007-2018 were included. Four PFASs - including perfluorohexane sulfonic acid (PFHxS), perfluorononanoic acid (PFNA), perfluoromethylheptane sulfonic acid (PFOS), and perfluorooctanoic acid (PFOA), were selected. Weighted quantile sum regression was used to evaluate mixed PFAS exposure and MetS. Multivariable logistic regression models were used to calculate odd ratio (OR) and 95 % confidence interval (95 % CI). Mediating analyses were used to evaluate the mediating effects of albumin.

Results

Comparing the highest with lowest quartile yielded a multivariable-adjusted OR (95 % CI) of 1.40 (1.14-1.72) for PFHxS, 1.36 (1.09-1.70) for PFNA, 1.26 (1.00-1.58) for PFOA, and 1.50 (1.19-1.88) for PFOS when associating MetS. Per unit increment in ln-transformed PFHxS, PFNA, PFOA, and PFOS concentrations was significantly associated with 16 %, 17 %, 13 %, and 15 % increased risk of MetS, respectively. When stratified by sex, the significant association between four PFASs and MetS was only noted in females. Mixed PFAS exposure was inversely associated with MetS, and 8.1 % of this association was mediated by serum albumin (P < 0.001).

Conclusions

Our findings indicate a significant and independent association of serum PFASs with MetS, and importantly this association was dose-dependent, sex-specific, and possibly mediated by serum albumin.

Biochar from paddy field - A solution to reduce PFAS pollution in the environment

Generally, activated carbons demonstrated a notable ability to capture long-chain PFAS, but exhibited relatively lower effectiveness for short-chain PFAS. Thirteen commercially available activated carbons in Japan underwent testing for their adsorption capacity of PFAS in water. The activated carbon derived from rice husk, Triporous™-PFAS, exhibited the highest adsorption capacity (over 95%) for PFAS from ultrashort-chain (perfluorocarbon chain: C1 for perfluorocarboxylic acid (PFCA) and C2 for perfluoroalkane sulfonic acid (PFSA)) to long-chain PFAS (C13 for PFCA and C10 for PFSA). An earlier lysimeter study highlighted Andosol, representative soil in Japan, as a potential medium for removing PFAS from irrigation water. Considering cultivating rice on Andosol fields and producing biochar from rice husks and rice straw, a new rice cultivation system is proposed. This system aims to facilitate continuous removal of PFAS from the environment in Asia. Japanese rice cultivation system produces not only rice but also biochar to remove PFAS from water circulation system. The total fluorine content in the tested activated carbon materials ranged from 0.18 to 38 μg g-1 F. Based on the results from background F blank and adsorption capacity, TriporousTM-PFAS-F was shown to be an option to lower the method detection limit for a proposed international standard method for measuring total PFAS.

Quantification of PFAS in rice and maize: Validation of a UHPLC-HRMS/MS isotopic dilution approach in support to food safety

In the present work, an analytical method for the quantification of per and poly fluoroalkyl substances (PFAS) in rice and maize has been developed and then validated with a metrological approach. PFAS are a group of human-made chemicals used in a variety of industries and consumer products for their water- and grease-resistant properties. Studies have shown that PFAS can contaminate soil and water, and there is concern about their bioaccumulation in edible plants, fruits, and cereals. The presence of PFAS has been identified in rice and other food products, including maize, as indicated by studies and scientific literature. This is particularly alarming since some PFAS have been associated with adverse health effects and rice and maize account for over 20% of the annual food intake worldwide. Despite this evidence, the regulation currently in place is not covering cereal matrices and limits of quantification for matrices encompassed by the current legislation are defined for a small group of PFAS. In this study an UHPLC-HRMS/MS based method was validated, obtaining a LOQ (Limit Of Quantification) ranging between 2 ng/kg and 32 ng/kg and robustness in line with EU guidelines and recommendation for PFAS in food. Additionally, a metrological approach was employed to estimate the uncertainty budget, utilizing modeling and experimental methods, and comparing the outcomes, aiming to characterize with high accuracy PFAS in rice and maize and support control bodies to assess contamination in suspected areas. A comparison of uncertainty of different approaches was conducted after applying the method to 30 real samples.

Development of a method using QuEChERS and LC-MS/MS for analysis of per- and polyfluoroalkyl substances in rice matrix

Detection of per- and polyfluoroalkyl substances (PFAS) in food is crucial for ensuring food safety. Therefore, we combined a quick, easy, cheap, rugged, and safe (QuEChERS) extraction method with liquid chromatography-triple-quadrupole mass spectrometry (LC-MS/MS) to detect 35 PFAS in rice. The solvents (water and acetonitrile) were adjusted to pH 2.4, a mixture of anhydrous MgSO4, NaCl, and NaOAc was used for extraction, and anhydrous MgSO4, a primary/secondary amine, and graphitized carbon black were applied for purification. The limits of detection and recovery were 0.005-0.100 ng·g-1 and 86.5 %-126.4 %, respectively. When this method was used to detect PFAS in packaged instant rice cooked in a microwave or boiled in water, the microwaved sample showed a lower PFAS content. However, both samples had PFAS contents within WHO guidelines and were safe for consumption. This method can be extended to detect PFAS levels in other foods exposed to packaging materials containing PFAS.

Perfluorooctanesulfonic Acid Alters the Plant's Phosphate Transport Gene Network and Exhibits Antagonistic Effects on the Phosphate Uptake

Per- and polyfluoroalkyl substances (PFASs), with significant health risks to humans and wildlife, bioaccumulate in plants. However, the mechanisms underlying plant uptake remain poorly understood. This study deployed transcriptomic analysis coupled with genetic and physiological studies using Arabidopsis to investigate how plants respond to perfluorooctanesulfonic acid (PFOS), a long-chain PFAS. We observed increased expressions of genes involved in plant uptake and transport of phosphorus, an essential plant nutrient, suggesting intertwined uptake and transport processes of phosphorus and PFOS. Furthermore, PFOS-altered response differed from the phosphorus deficiency response, disrupting phosphorus metabolism to increase phosphate transporter (PHT) transcript. Interestingly, pht1;2 and pht1;8 mutants showed reduced sensitivity to PFOS compared to that of the wild type, implying an important role of phosphate transporters in PFOS sensing. Furthermore, PFOS accumulated less in the shoots of the pht1;8 mutant, indicating the involvement of PHT1;8 protein in translocating PFOS from roots to shoots. Supplementing phosphate improved plant's tolerance to PFOS and reduced PFOS uptake, suggesting that manipulating the phosphate source in PFOS-contaminated soils may be a promising strategy for minimizing PFOS uptake by edible crops or promoting PFOS uptake during phytoremediation. This study highlighted the critical role of phosphate sensing and transport system in the uptake and translocation of PFOS in plants.

Tissue-specific distribution and bioaccumulation of perfluoroalkyl acids, isomers, alternatives, and precursors in citrus trees of contaminated fields: Implication for risk assessment

The ingestion of fruits containing perfluoroalkyl acids (PFAAs) presents potential hazards to human health. This study aimed to fill knowledge gaps concerning the tissue-specific distribution patterns and bioaccumulation behavior of PFAAs and their isomers, alternatives, and precursors (collectively as per-/polyfluoroalkyl substances, PFASs) within citrus trees growing in contaminated fields. It also assessed the potential contribution of precursor degradation to human exposure risk of PFASs. High concentrations of total target PFASs (∑PFASstarget, 92.45-7496.16 ng/g dw) and precursors measured through the total oxidizable precursor (TOP) assay (130.80-13979.21 ng/g dw) were found in citrus tree tissues, and short-chain PFASs constituted the primary components. The total PFASs concentrations followed the order of leaves > fruits > branches, bark > wood, and peel > pulp > seeds. The average contamination burden of peel (∑PFASstarget: 57.75%; precursors: 71.15%) was highest among fruit tissues. Bioaccumulation factors (BAFs) and translocation potentials of short-chain, branched, or carboxylate-based PFASs exceeded those of their relatively hydrophobic counterparts, while ether-based PFASs showed lower BAFs than similar PFAAs in above-ground tissues of citrus trees. In the risk assessment of residents consuming contaminated citruses, precursor degradation contributed approximately 36.07% to total PFASs exposure, and therefore should not be ignored.

Is it raining PFAS in France? An analysis of 52 PFAS at nanogram per liter levels in French rainwaters during autumn season

Per- and polyfluoroalkyl substances (PFAS) are of increasing concern due to their pervasive nature, high persistence, and their impacts on human health and the environment. Many studies have attempted to assess the presence of PFAS along the water cycle, but few have analyzed rainwater PFAS content and its contribution to water contamination. The present study aims to improve knowledge by providing the first analysis of PFAS rainwater samples from France. A total of 52 PFAS were analyzed at nanogram per liter levels in rainwater samples collected in 14 locations in France using a cutting-edge liquid chromatography-tandem mass spectrometry (LC/MS/MS) method for multiresidue determination. Depending on the quantity of rainwater collected, the PFAS concentrations were analyzed either by direct injection or after solid-phase extraction (SPE), allowing to quantify 20 PFAS with a limit of quantification (LOQ) ≤ 100 ng/L and 52 PFAS with a LOQ ≤ 1 ng/L, respectively. For the five locations for which the collected samples were analyzed by direct injection, no PFAS could be detected (i.e., their concentrations in the samples were below the LOQs of the method). The samples from four locations out of the nine analyzed by SPE-LC/MS/MS show results above the method's LOQs for up to 10 PFAS. Among the quantified PFAS, three compounds (perfluorononanoic acid, perfluoroundecanoic acid, and perfluorohexanoic acid) have been found to be of most significance. These results bring out the presence of PFAS in rainwater samples in France, highlighting the need for PFAS environmental surveillance and risk assessment and the necessity of continuous improvement of existing analysis methods.