Anthropogenic Drivers of Variation in Concentrations of Perfluoroalkyl Substances in Otters (Lutra lutra) from England and Wales

Emerging and legacy per- and polyfluoroalkyl substances from offshore oilfields and receiving water in China

Per- and polyfluoroalkyl substances (PFASs) are extensively utilized as oilfield production chemicals and aqueous film-forming foams (AFFFs) in oilfields. A comprehensive investigation was undertaken to analyze twenty per-and polyfluoroalkyl substances (PFASs), including three emerging PFASs in drill cuttings, slurry and produced water from offshore oilfields in three main sea areas of China. The investigation results were further compared with those in their receiving water. The concentration ranges of ΣPFASs in drill cuttings, slurry as well as produced water were 1049-3473 ng/g and 81.9 ng/L-2090 ng/L, respectively. In comparison, the concentrations range of PFASs in receiving water was 46.2-99.7 ng/L. Both sodium p-perfluorous nonenoxybenzenesulfonate (OBS) and hexafluoropropylene oxide dimer acid (HFPO-DA) were identified as the predominant PFASs detected at elevated concentrations in drilling cuttings, slurry, and produced water, demonstrating their extensive utilization in such environments. HFPO-DA and OBS concentrations in produced water exceeded those in receiving water by 1-2 orders of magnitude. Principal component analysis (PCA) analyses revealed that the compositions of PFASs in the receiving water samples exhibited significant similarity to those in drill cuttings, slurry and produced water from oilfields. It was indicated that discharges from oilfields were the primary contributors of PFASs in their receiving water. In 60-96% of samples from produced water in the Bohai Sea and South China Sea oilfields, as well as receiving water adjacent to the Bohai Sea oilfields, the risk quotient (RQ) of HFPO-DA ranged 0.1-1, indicating moderate ecological risks to aquatic organisms. In contrast, legacy PFASs generally showed lower risk levels.

Unveiling the Contribution of Hydrogen Radicals to Per- and Polyfluoroalkyl Substances (PFASs) Defluorination: Applicability and Degradation Mechanisms

At present, the defluorination of per- and polyfluoroalkyl substances (PFASs), including perfluoroether compounds as substitutes of perfluorooctanoic acid (PFOA) and perfluorooctanesulfonate, is limited by the effective active species produced during the oxidation-reduction process. The contribution of the hydrogen radical (•H) as a companion active substance in the photoreduction and electrocatalytic degradation of PFASs has been neglected. Herein, we demonstrate that perfluorocarboxylic acids and perfluoroether compounds such as PFOA and hexafluoropropylene oxide dimer acid (GenX) underwent near-complete photodegradation and effective defluorination by continuously generating •H through perfluoroalkyl radical activation of water under UV irradiation without any reagents and catalysts. Importantly, the initial dissolved oxygen, H+, and impurities in surface water scarcely inhibited the defluorination of the PFASs. The difference in the defluorination mechanism between PFOA and GenX under the action of •H was elucidated by combining theoretical calculations with targeted and nontargeted analysis methods. The investigation of the photodegradation of different PFASs indicates that perfluoroether compounds were not easily photodegraded via reduction of •H compared with other compounds, whereas polyfluorinated compounds in which some F atoms were replaced with Cl were more prone to elimination. However, the UV/•H system was ineffective against perfluorosulfonic acids. This study provides an unprecedented perspective for further development of the removal technology of PFASs and the design of alternative PFASs that are easy to eliminate.

Trends in extraction techniques for the determination of organic micropollutants in liver tissues of vertebrates

Determining organic micropollutants in liver samples of apex species is of foremost importance for biomonitoring studies, as it can provide evidence of environmental pollution and exposure of living organisms to chemicals. This review aims to provide a 4-year overview and summarize the trends in the extraction methodologies to determine both polar and non-polar organic micropollutants in liver samples from organisms of higher trophic levels. The dominant extraction techniques including ultrasound-assisted extraction (UAE), pressurized liquid extraction (PLE), Soxhlet, and QuEChERS, as well as additional steps and/or modifications applied in the reviewed studies, are presented and critically discussed. The latest trends in these methods as well as a comparison between them considering elapsed time, robustness, cost, and environmental fingerprint are also provided.

Network analysis to reveal the most commonly detected compounds in predator-prey pairs in freshwater and marine mammals and fish in Europe

Marine and freshwater mammalian predators and fish samples, retrieved from environmental specimen banks (ESBs), natural history museum (NHMs) and other scientific collections, were analysed by LIFE APEX partners for a wide range of legacy and emerging contaminants (2545 in total). Network analysis was used to visualize the chemical occurrence data and reveal the predominant chemical mixtures for the freshwater and marine environments. For this purpose, a web tool was created to explore these chemical mixtures in predator-prey pairs. Predominant chemicals, defined as the most prevalent substances detected in prey-predator pairs were identified through this innovative approach. The analysis established the most frequently co-occurring substances in chemical mixtures from AP&P in the marine and freshwater environments. Freshwater and marine environments shared 23 chemicals among their top 25 predominant chemicals. Legacy chemical, including perfluorooctanesulfonic acid (PFOS), brominated diphenyl ethers (BDEs), polychlorinated biphenyls (PCBs), hexachlorobenzene and mercury were dominant chemicals in both environments. Furthermore, N-acetylaminoantipyrine was a predominant pharmaceutical in both environments. The LIFE APEX chemical mixture application (https://norman-data.eu/LIFE_APEX_Mixtures) was proven to be useful to establish most prevalent compounds in terms of number of detected counts in prey-predator pairs. Nonetheless, further research is needed to establish food chain associations of the predominant chemicals.

Insights into PFAS contaminants before and after sewage discharges into a marine protected harbour

Per and polyfluoroalkyl substances (PFAS) and their degradation products are a concern to human and ecosystem health. Wastewater treatment plants are not efficient at removing PFAS compounds and are thought to be a major source of these compounds to marine environments. The sewerage infrastructure in the UK, has over 20,000 combined stormwater overflows (CSOs). These CSOs are relief values whereby untreated wastewater can discharge under permit from the Environment Agency with exceptional rain/snowfall conditions. CSOs discharged 3.6 million monitored hours of untreated wastewater into English rivers and coasts in 2023. Concerns have been raised about the proximity of these CSO discharges to highly protected marine habitats. This study is the first to determine that PFAS concentrations are elevated in a highly protected marine bay (Langstone Harbour, England) following recent sewage releases compared to an extended period without discharge. Analysis was carried out into a suite of 54 PFAS compounds of which only one (PFHpA) was detectable above LOD prior to discharges but 8 afterwards. These included banned PFOS (Linear and Branched 8.6 ng/L ∓ 0.90) and PFOA (2.9 ng/L ∓ 0.29) which were above annual average EQS for inland and 'other' surface waters. Most of the PFAS compounds detected doubled in concentration above LODs. These two-fold increases we discuss are likely conservative estimates based on the use of LODs and tidal conditions. Additional Oysters (Crassostrea gigas) and Seaweed (Fucus vesiculosus) were taken revealing high concentrations of the shorter chain PFBA (6.99μg/kg ∓ 2.42 ww) in seaweed samples. These seaweeds were calculated to have conservative bioaccumulation factors (BAF) > 6000 for PFBA indicating these algae might be an important reservoir of some PFAS contamination. We discuss these results in the context of the largescale discharges of untreated wastewater nationally and globally, and call upon a need for a better understanding of the transfer of PFAS contaminants into marine food chains.

Exploring fluctuating asymmetry in two recovering populations of the Eurasian otter

The Eurasian otter is a wide-ranging semi-aquatic mammal that underwent a significant population decline in the last century, leading to local extinctions, reduction and fragmentation of populations. The individuals of populations exposed to both external and internal stress may present the inability to produce a specific developmental outcome, generating developmental 'noise' (developmental instability (DI)). Factors contributing to DI include inbreeding depression, population bottlenecks, habitat loss and exposure to pollution. We analysed fluctuating asymmetry (FA) as a proxy of DI in two European otter populations that experienced a major decline in the 1990s. Using three-dimensional geometric morphometrics methods on skull samples of otters from the UK and Sweden, we compared the degree of FA both between populations before, during and after the decline. We found a higher FA in the UK populations compared with Sweden. The level of asymmetry differed significantly over time only in the UK population, where it was higher during the decline phase. FA in the UK populations can be attributed to the specific impact of polychlorinated biphenyls pollution that caused a bottleneck. More generally, our study suggests that habitat loss, pollution and limited gene flow may contribute to DI in declining otter populations, highlighting the need for continued investigation to identify and quantify the specific stressors behind this trend in local populations.

First report of accumulation of perfluorooctane sulfonate (PFOS) in platypuses (Ornithorhynchus anatinus) in New South Wales, Australia

The platypus (Ornithorhynchus anatinus) is a semi-aquatic monotreme that occupies a high trophic position in the freshwater ecosystems of eastern mainland Australia and Tasmania. Platypuses are continuously exposed to anthropogenic contaminants including perfluorooctane sulfonate (PFOS). This study examined PFOS concentrations in the livers of deceased platypuses (eight wild; one captive) that were opportunistically collected across NSW over a two- and a half-year period. There was a large variation in PFOS concentrations, ranging from < 1 µg/kg to 1200 µg/kg. This study presents the first report of PFOS contamination in platypuses, revealing their PFOS levels are broadly similar to those found in river otters (Lutra canadensis) and lower than those in American mink (Mustela vison), both which occupy similar ecological niches in freshwater systems. This study raises concerns about the impact of PFOS on platypus health.

Persistence of PFOA Pollution at a PTFE Production Site and Occurrence of Replacement PFASs in English Freshwaters Revealed by Sentinel Species, the Eurasian Otter (Lutra lutra)

Concentrations of 33 PFASs were determined in 20 Eurasian otters, sampled 2015-2019, along a transect away from a factory, which used PFOA in PTFE manufacture. Despite cessation of usage in 2012, PFOA concentrations remained high near the factory (>298 μg/kg ww <20 km from factory) and declined with increasing distance (<57 μg/kg ww >150 km away). Long-chain legacy PFASs dominated the Σ33PFAS profile, particularly PFOS, PFOA, PFDA, and PFNA. Replacement compounds, PFECHS, F-53B, PFBSA, PFBS, PFHpA, and 8:2 FTS, were detected in ≥19 otters, this being the first report of PFBSA and PFECHS in the species. Concentrations of replacement PFASs were generally lower than legacy compounds (max: 70.3 μg/kg ww and 4,640 μg/kg ww, respectively). Our study underscores the utility of otters as sentinels for evaluating mitigation success and highlights the value of continued monitoring to provide insights into the longevity of spatial associations with historic sources. Lower concentrations of replacement, than legacy, PFASs likely reflect their lower bioaccumulation potential, and more recent introduction. Continued PFAS use will inevitably lead to increased environmental and human exposure if not controlled. Further research is needed on fate, toxicity, and bioaccumulation of replacement compounds.

Fluorine mass balance analysis in wild boar organs from the Bohemian Forest National Park

Wild boars have been reported as bioindicators for per- and polyfluoroalkyl substances (PFAS) in a variety of studies. However, data about PFAS levels in wild boars from sites with limited industrial and general human activity is scarce. In this study, wild boar (Sus scrofa) organs from the Bohemian Forest National Park (Czech Republic) were used as bioindicators for PFAS pollution. In this work, 29 livers and 24 kidneys from 30 wild boars (0.5-5 years) were investigated using a fluorine mass balance approach. For this, the samples were measured using high performance liquid chromatography with electrospray ionisation tandem mass spectrometry (HPLC-ESI-MS/MS), targeting 30 PFAS, including legacy and replacement PFAS, direct total oxidisable precursor assay (dTOPA) and combustion ion chromatography (CIC). Perfluorocarboxylic acids (PFCAs) from C7 to C14 and perfluorooctanesulfonic acid (PFOS) were detected in >50 % of samples. In the livers, PFCAs dominated the profile with median concentrations of 230 μg/kg for perfluorononanoic acid (PFNA) and 75 μg/kg perfluorooctanoic acid (PFOA). PFOA and PFNA concentrations in the livers were one order of magnitude higher than in livers from wild boars caught in rural NE Germany considered as background concentration. PFOS in liver contributed only 30 % to the Σc(PFASTarget) with a median concentration of 170 μg/kg. Kidneys and livers contain an average of 2460 μg F/kg and 6800 μg F/kg extractable organic fluorine (EOF) respectively. Σc(PFASTarget) add up to a maximum of 10 % of the extractable organic fluorine. After oxidisation of the samples, PFOA, PFNA and Σc(PFASdTOPA) increased in livers, but could not explain the EOF. The elevated concentration of PFOA and PFNA may indicate differences in biomagnification for different habitats or an unidentified PFAS source in proximity to the national park.

Lack of detection of SARS-CoV-2 in British wildlife 2020-21 and first description of a stoat (Mustela erminea) Minacovirus

Repeat spillover of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) into new hosts has highlighted the critical role of cross-species transmission of coronaviruses and establishment of new reservoirs of virus in pandemic and epizootic spread of coronaviruses. Species particularly susceptible to SARS-CoV-2 spillover include Mustelidae (mink, ferrets and related animals), cricetid rodents (hamsters and related animals), felids (domestic cats and related animals) and white-tailed deer. These predispositions led us to screen British wildlife with sarbecovirus-specific quantitative PCR and pan coronavirus PCR assays for SARS-CoV-2 using samples collected during the human pandemic to establish if widespread spillover was occurring. Fourteen wildlife species (n=402) were tested, including: two red foxes (Vulpes vulpes), 101 badgers (Meles meles), two wild American mink (Neogale vison), 41 pine marten (Martes martes), two weasels (Mustela nivalis), seven stoats (Mustela erminea), 108 water voles (Arvicola amphibius), 39 bank voles (Myodes glareolous), 10 field voles (Microtus agrestis), 15 wood mice (Apodemus sylvaticus), one common shrew (Sorex aranaeus), two pygmy shrews (Sorex minutus), two hedgehogs (Erinaceus europaeus) and 75 Eurasian otters (Lutra lutra). No cases of SARS-CoV-2 were detected in any animals, but a novel minacovirus related to mink and ferret alphacoronaviruses was detected in stoats recently introduced to the Orkney Islands. This group of viruses is of interest due to pathogenicity in ferrets. The impact of this virus on the health of stoat populations remains to be established.

Legacy and Emerging Per- and Polyfluoroalkyl Substances Surveillance in Bufo gargarizans from Inlet Watersheds of Chaohu Lake, China: Tissue Distribution and Bioaccumulation Potential

Amphibians are sensitive biomonitors of environmental pollutants but reports regarding per- and polyfluoroalkyl substances (PFAS), a class of synthetic organofluorine substances, are limited. In this study, samples of water and Chinese toads (Bufo gargarizans) were collected in Chaohu Lake, China. Tissue-specific bioaccumulation characteristics of 39 PFAS, including 19 perfluoroalkyl acids (PFAAs), 8 emerging PFAS, and 12 PFAA precursors, were investigated, and the levels of some biochemical indicators were determined. The highest PFAS concentrations were found in the liver [215.97 ng/g dry weight (dw)] of Chinese toads, followed by gonads (135.42 ng/g dw) and intestine (114.08 ng/g dw). A similar tissue distribution profile was found between legacy and emerging PFAS in the toads, and the occurrence of two emerging PFAS, 2,3,3,3-tetrafluoro-2-propanoate (HFPO-DA) and 6:2 hydrogen-substituted polyfluorooctane ether sulfonate (6:2 H-PFESA) in the amphibians were for the first time reported. Field-based bioaccumulation factors of HFPO-DA were higher than perfluorooctanoic acid, indicating the higher bioaccumulation potential of this emerging PFAS than the legacy C8 compound. Males had significantly higher gonad PFAS levels than females while estradiol levels in gonads increased with increasing concentrations of certain PFAS (e.g., 6:2 H-PFESA), implying that PFAS may trigger estrogenic effects in the toads, especially for male toads.

Occurrences and fates of per- and polyfluoralkyl substances in textile dyeing wastewater along full-scale treatment processes

Industrial wastewater is a substantial source of per- and polyfluoroalkyl substances (PFASs) in the environment. However, very limited information is available on the occurrences and fates of PFASs along industrial wastewater treatment processes, particularly for the textile dyeing industry where PFASs occur extensively. Herein, the occurrences and fates of 27 legacy and emerging PFASs were investigated along the processes of three full-scale textile dyeing wastewater treatment plants (WWTPs) based on UHPLC-MS/MS in combination with self-developed solid extraction protocol featuring selective enrichment for ultrasensitive analysis. The total PFASs ranged at 630-4268 ng L-1 in influents, 436-755 ng L-1 in effluents, and 91.5-1182 μg kg-1 in the resultant sludge. PFAS species distribution varied among WWTPs, with one WWTP dominated by legacy perfluorocarboxylic acids while the other two dominated by emerging PFASs. Perfluorooctane sulfonate (PFOS) was trivial in the effluents from all the three WWTPs, indicating its diminished use in textile industry. Various emerging PFASs were detected at different abundances, demonstrating their use as alternatives to legacy PFASs. Most conventional processes of the WWTPs were inefficient in removing PFASs, especially for the legacy PFASs. The microbial processes could remove the emerging PFASs to different extents, whereas commonly elevated the concentrations of legacy PFASs. Over 90% of most PFASs could be removed by reverse osmosis (RO) and was enriched into the RO concentrate accordingly. The total oxidizable precursors (TOP) assay revealed that the total concentration of PFASs was increased by 2.3-4.1 times after oxidation, accompanied by formation of terminal perfluoroalkyl acids (PFAAs) and degradation of emerging alternatives to various extents. This study is believed to shed new light on the monitoring and management of PFASs in industries.

Present in the Aquatic Environment, Unclear Evidence in Top Predators-The Unknown Effects of Anti-Seizure Medication on Eurasian Otters (Lutra lutra) from Northern Germany

Emerging contaminants are produced globally at high rates and often ultimately find their way into the aquatic environment. These include substances contained in anti-seizure medication (ASM), which are currently appearing in surface waters at increasing concentrations in Germany. Unintentional and sublethal, chronic exposure to pharmaceuticals such as ASMs has unknown consequences for aquatic wildlife. Adverse effects of ASMs on the brain development are documented in mammals. Top predators such as Eurasian otters (Lutra lutra) are susceptible to the bioaccumulation of environmental pollutants. Still little is known about the health status of the otter population in Germany, while the detection of various pollutants in otter tissue samples has highlighted their role as an indicator species. To investigate potential contamination with pharmaceuticals, Eurasian otter brain samples were screened for selected ASMs via high-performance liquid chromatography and mass spectrometry. Via histology, brain sections were analyzed for the presence of potential associated neuropathological changes. In addition to 20 wild otters that were found dead, a control group of 5 deceased otters in human care was studied. Even though none of the targeted ASMs were detected in the otters, unidentified substances in many otter brains were measured. No obvious pathology was observed histologically, although the sample quality limited the investigations.

Association of serum per- and polyfluoroalkyl substances and gestational anemia during different trimesters in Zhuang ethnic pregnancy women of Guangxi, China

BACKGROUND

Gestational anemia is a complication of pregnancy, and a low level of hemoglobin (Hb) has been linked to adverse pregnancy outcomes. Previous studies reported that PFASs were more strongly associated with Hb than red blood cells, indicating that Hb is more susceptible to the effect of PFASs. However, the evidences regarding the effects of per- and polyfluoroalkyl substances (PFASs) on gestational anemia are currently limited. Therefore, it is important to explore the effects of PFASs on anemia in Chinese pregnant women.

METHODS

A total of 821 pregnant women were recruited between June 2015 and April 2019 in the Guangxi Zhuang Birth Cohort. The concentrations of PFASs were assessed in maternal serum before 12 gestational weeks. To determine both individual and combined associations of PFASs exposure with anemia in the three stages of pregnancy, binary logistic regression, Bayesian kernel machine regression (BKMR), and weighted quantile sum (WQS) regression models were employed.

RESULTS

In single-pollutant analysis, maternal exposure to perfluorododecanoic acid (PFDoA) and perfluoroheptanoic acid (PFHpA) were associated with anemia in the first trimester, exposure to PFHpA and perfluorobutanesulfonic acid (PFBS) were associated with anemia in the second trimester, and exposure to perfluorodecanoic acid (PFDA) and perfluorononanoic acid (PFNA) were associated with anemia in the third trimester. Notably, perfluoroundecanoic acid (PFUnA) had a nonlinear association with anemia in the third trimester. In multiple-pollutant analysis, a positive association of PFDoA with anemia in the first trimester and a negative association of PFBS with anemia in the second trimester were confirmed by BKMR. Exposure to PFASs mixture was not associated with anemia in all three trimesters. In WQS, there was a significantly negative association between the PFAS mixture and anemia in the second trimester.

CONCLUSION

Maternal exposure to PFASs is associated with gestational anemia in different trimesters.

Making use of apex predator sample collections: an integrated workflow for quality assured sample processing, analysis and digital sample freezing of archived samples

Using monitoring data from apex predators for chemicals risk assessment can provide important information on bioaccumulating as well as biomagnifying chemicals in food webs. A survey among European institutions involved in chemical risk assessment on their experiences with apex predator data in chemical risk assessment revealed great interest in using such data. However, the respondents indicated that constraints were related to expected high costs, lack of standardisation and harmonised quality criteria for exposure assessment, data access, and regulatory acceptance/application. During the Life APEX project, we demonstrated that European sample collections (i.e. environmental specimen banks (ESBs), research collection (RCs), natural history museums (NHMs)) archive a large variety of biological samples that can be readily used for chemical analysis once appropriate quality assurance/control (QA/QC) measures have been developed and implemented. We therefore issued a second survey on sampling, processing and archiving procedures in European sample collections to derive key quality QA/QC criteria for chemical analysis. The survey revealed great differences in QA/QC measures between ESBs, NHMs and RCs. Whereas basic information such as sampling location, date and biometric data were mostly available across institutions, protocols to accompany the sampling strategy with respect to chemical analysis were only available for ESBs. For RCs, the applied QA/QC measures vary with the respective research question, whereas NHMs are generally less aware of e.g. chemical cross-contamination issues. Based on the survey we derived key indicators for assessing the quality of biota samples that can be easily implemented in online databases. Furthermore, we provide a QA/QC workflow not only for sampling and processing but also for the chemical analysis of biota samples. We focussed on comprehensive analytical techniques such as non-target screening and provided insights into subsequent storage of high-resolution chromatograms in online databases (i.e. digital sample freezing platform) to ultimately support chemicals risk assessment.

Country-wide genetic monitoring over 21 years reveals lag in genetic recovery despite spatial connectivity in an expanding carnivore (Eurasian otter, Lutra lutra) population

Numerous terrestrial mammal species have experienced extensive population declines during past centuries, due largely to anthropogenic pressures. For some species, including the Eurasian otter (Lutra lutra), environmental and legal protection has more recently led to population growth and recolonization of parts of their historic ranges. While heralded as conservation success, only few such recoveries have been examined from a genetic perspective, i.e. whether genetic variability and connectivity have been restored. We here use large-scale and long-term genetic monitoring data from UK otters, whose population underwent a well-documented population decline between the 1950s and 1970s, to explore the dynamics of a population re-expansion over a 21-year period. We genotyped otters from across Wales and England at five time points between 1994 and 2014 using 15 microsatellite loci. We used this combination of long-term temporal and large-scale spatial sampling to evaluate 3 hypotheses relating to genetic recovery that (i) gene flow between subpopulations would increase over time, (ii) genetic diversity of previously isolated populations would increase and that (iii) genetic structuring would weaken over time. Although we found an increase in inter-regional gene flow and admixture levels among subpopulations, there was no significant temporal change in either heterozygosity or allelic richness. Genetic structuring among the main subpopulations hence remained strong and showed a clear historical continuity. These findings highlight an underappreciated aspect of population recovery of endangered species: that genetic recovery may often lag behind the processes of spatial and demographic recovery. In other words, the restoration of the physical connectivity of populations does not necessarily lead to genetic connectivity. Our findings emphasize the need for genetic data as an integral part of conservation monitoring, to enable the potential vulnerability of populations to be evaluated.

Effects of exposure to per- and polyfluoroalkyl substances on vaccine antibodies: A systematic review and meta-analysis based on epidemiological studies

Vaccines are essential for children to defend against infection. Per- and polyfluoroalkyl substances (PFAS) are emerging contaminants with the characteristics of persistence and bioaccumulation. PFAS exposure can affect the function of the nervous, endocrine, and immune system of animals and humans. We aimed to conduct a systematic review and meta-analysis of the epidemiological studies investigating potential relationships between PFAS exposure and vaccine antibody levels, and assessed whether PFAS would affect vaccine response in healthy children. A literature search was conducted in PubMed, Web of Science, and Scopus databases up to February 2022. We chose studies that measured serum vaccines antibodies and PFAS concentrations of the participants. Essential information, including mean difference of percentage change, regression coefficient, odds ratio, Spearman correlation coefficient, and 95% confidence intervals, were extracted from the selected studies to conduct descriptive analysis and meta-analysis where appropriate. The qualities of these studies were evaluated as well. Finally, nine epidemiological studies about children met our inclusion criteria. A high degree of heterogeneity is observed in terms of breastfeeding time, confounder control, and detection method. Exposure to perfluorooctanoic acid and perfluorohexane sulfonic acid is negatively associated with tetanus antibody level in children without heterogeneity by Cochran's Q test (p = 0.26; p = 0.55), and exposure to perfluorohexane sulfonate is negatively associated with tetanus antibody level but with heterogeneity (p = 0.04). This comprehensive review suggests that PFAS can have adverse health effects on children by hindering the production of vaccine antibodies. There are some consistent and negative associations between children exposure to certain PFAS and tetanus antibody level. The association of the other four vaccines (measles, rubella, mumps, and influenza) with PFAS remains uncertain, because very few studies are available. Further studies are needed to validate the possible associations.