First indication of perfluoroalkyl substances in human serum from Papua New Guinea

Serum concentrations of PFAS across Australian States and Territories

BACKGROUND

Australia's long running human biomonitoring (HBM) program has provided information on per and poly-fluoroalkyl substances (PFAS) serum concentrations in the general population since 2002. The program is based on pooling and analysis of surplus, de-identified, pathology specimens predominantly sourced from Australia's north-eastern state Queensland (QLD). To date, potential nationwide spatial differences across Australia have not been assessed.

AIM

The aim of this study was to assess spatial variation of background PFAS serum concentrations across all Australian States and Territories, and to assess if the long running HBM program, representing samples biased towards QLD, can be considered a national reference.

METHODS

Surplus pathology serum samples were collected and stratified by States/Territories based on postcode. Pools representing three age groups (5-15, 31-45 and ≥ 60 years), stratified by sex were created. Up to two pools for each age/sex strata, consisting of up to 100 individuals, were created for Australian States and major Territories. Samples were analysed for PFAS using high-performance liquid chromatography-mass-spectrometry.

RESULTS AND DISCUSSION

There was a high degree of consistency in the PFAS serum concentration for a given age/sex among pools from the different States/Territories, particularly for perfluoro carboxylic acids. This suggests that PFAS serum concentrations and associated exposure is relatively consistent across Australia. PFAS concentrations measured in QLD pools were not statistically different from the national average, suggesting that the current Australian HBM program can be considered as a national reference of background PFAS serum concentrations.

Spatial variations in per- and polyfluoroalkyl substance concentrations in pooled sera from inland, coastal, and island populations

Per- and polyfluoroalkyl substances (PFAS) are a class of ubiquitously detected chemicals, some of which are highly persistent and bioaccumulative in humans. Within the general population, dietary ingestion is considered a primary pathway for PFAS exposure, and seafood consumption specifically has been associated with higher serum PFAS concentrations. Proximity of residence to the ocean may influence dietary habits, particularly seafood consumption, and exposure to geographically specific PFAS sources such as sea spray aerosols (SSA). The objective of this study was to evaluate potential spatial trends in serum PFAS concentrations between Australian coastal and island populations compared to those with inland residency. Human sera were obtained from deidentified surplus pathology samples and pooled with respect to geographical location, sex (male or female), and age group (males: ≥15-<45 years, ≥45 years; females: ≥15-<45 years, ≥45-<60 years, ≥60 years) stratification criteria. Serum samples were then analysed for PFAS using High Performance Liquid Chromatography-Mass Spectrometry (HP LC-MS). A total of 13 of the 45 targeted PFAS were quantifiable in at least one pooled sample, including the detection of perfluorooctane sulfonate (PFOS) replacement compounds 5:3 fluorotelomer carboxylic acid (5:3 FTCA) and potassium 9-chlorohexadecafluoro-3-oxanonane-1-sulfonate (9Cl-F53B). Significant spatial trends were observed in males aged ≥45 years, with serum concentrations of PFOS, perfluorobutanoic acid (PFBA), perfluorodecanoic acid (PFDA) and perfluoroheptane sulfonic acid (PFHpS) demonstrated to be 32-77% higher in pooled samples from island locations compared with inland. A similar trend was observed for PFHpS in coastal locations. Whilst deidentification of samples limited inferences about exposure pathways associated with the observed trends, this study indicated the feasibility of utilising pooled samples for assessing spatial variations in serum PFAS concentrations between geographically distinct subpopulations.

First insight into the formation of transformation products of a biopesticide guvermectin in rat and its health risk

Guvermectin is a new chemical isolated from the microbial metabolites and is registered as a novel plant growth regulator. However, the biotransformation behavior and toxicity of guvermectin to mammals remain unclear and have unknown implications for consumers or occupationally exposed persons. Therefore, we investigated the biotransformation of guvermectin in vivo and in vitro, its effects on CYP450s activities, and its oral toxicity in rats. The results showed that guvermectin could be rapidly absorbed when administered orally and eliminated rapidly in the serum, with a half-life of 6.3 h. Four phase І metabolism products of guvermectin in the serum were screened and identified using UPLC-QTOF/MS. Two products, adenine and psicofuramine, were confirmed using reference standards. Hydrolysis and oxidation reactions were the main transformation pathways. Oral toxicity tests in rats showed that guvermectin exhibited light toxicity to rats (LC50 > 5000 mg/kg b.w.). However, an in vitro probe drug experiment revealed that guvermectin could induce CYP2D6 activity, and a lower concentration of guvermectin exhibited a stronger effect on CYP2D6 than higher concentration (1.38-fold). Molecular docking studies implied that guvermectin was an antagonist of CYP1A2, CYP2C9, and CYP3A4. These findings provided a better understanding of the environmental and human health risks associated with guvermectin and promote its rational use. However, the potential risk of endocrine disruption can not be ignored due to the presence of nucleoside-like metabolites.

Environmental occurrence, bioaccumulation and human risks of emerging fluoroalkylether substances: Insight into security of alternatives

Per- and polyfluoroalkyl substances (PFASs) are widely used due to their unique structure and excellent performance, while also posing threats on ecosystem, especially long-chain perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA). As the control of conventional PFASs, fluoroalkylether substances (ether-PFASs) as alternatives are constantly emerging. Subsequently, the three representative ether-PFASs, chlorinated polyfluoroalkyl ether sulfonic acid (F-53B), hexafluoropropylene oxide-dimer acid (HFPO-DA), and 4,8-Dioxa-3H-perfluorononanoicacid (ADONA) are discovered and have received more attention in the environment and ecosystem. But their security is now also being challenged. This review systematically assesses their security from six dimensions including environmental occurrence in water, soil and atmosphere, as well as bioaccumulation and risk in plants, animals and humans. High substitution level is observed for F-53B, whether in environment or living things. Like PFOS or even more extreme, F-53B exhibits high biomagnification ability, transmission efficiency from maternal to infant, and various biological toxicity effects. HFPO-DA still has a relatively low substitution level for PFOA, but its use has emerged in Europe. Although it is less detected in human bodies and has a higher metabolic rate than PFOA, the strong migration ability of HFPO-DA in plants may pose dietary safety concerns for humans. Research on ADONA is limited, and currently, it is detected in Germany frequently while remaining at trace levels globally. Evidently, F-53B has shown increasing risk both in occurrence and toxicity compared to PFOS, and HFPO-DA is relatively safe based on available data. There are still knowledge gaps on security of alternatives that need to be addressed.

Association between exposure to per- and perfluoroalkyl substances (PFAS) and reproductive hormones in human: A systematic review and meta-analysis

BACKGROUND

Per- and polyfluoroalkyl substances (PFAS) is persistent endocrine disrupting chemicals. Previous evidence suggests that exposure to PFAS is associated with reproductive hormone levels, but the results of relevant studies are inconsistent. The objective of our study is to determine the association between exposure to PFAS and reproductive hormone levels in gender-specific general population.

METHOD

Based on scientific search strategies, we systematically searched PubMed, Web of Science, Embase, Medline, and Scopus to obtain the eligible studies published before January 21, 2023. The quality of the included articles was assessed using the Office of Health Assessment and Translation (OHAT) Risk of Bias tool. We combined the β coefficient and 95% confidence intervals (CI) using Stata.17 with random-effect model or fixed-effect model. We also performed subgroup analysis, sensitivity analysis, and Begger's and Egger's tests.

RESULTS

Eleven studies involving 7714 participants were included. Meta-analysis showed that PFHxS exposure was positively associated with estradiol (E2) levels in female [β = 0.030, 95% CI: (0.013, 0.046), P = 0.000]. A negative association was found between PFOA [β = -0.012, 95% CI: (-0.023, -0.002), P = 0.017] and PFOS [β = -0.011; 95% CI: (-0.021, -0.000), P = 0.042] exposure with male testosterone (TT) levels. In the subgroup analysis, there were stronger associations in children than in adults. And the high heterogeneity was mainly due to the cross-sectional studies. Publication bias was not found in most of the analyses.

CONCLUSION

Our study showed that PFAS exposure was significantly associated with reproductive hormone levels. Further related studies are needed to identify the association and potential mechanism in the future.