The driving factors of per- and polyfluorinated alkyl substance (PFAS) accumulation in selected fish species: The influence of position in river continuum, fish feed composition, and pollutant properties

Microplastics meet micropollutants in a Central European river stream: adsorption of pollutants to microplastics under environmentally relevant conditions

Microplastics have emerged as pervasive pollutants in aquatic environments, and their interaction with organic contaminants poses a significant environmental challenge. This study aimed to explore the adsorption of micropollutants onto microplastics in a river, examining different plastic materials and the effect of aging on adsorption capacity. Microplastics (low-density polyethylene (LDPE), polyethylene terephthalate (PET), and polyvinyl chloride (PVC)) were introduced into a river stream, and a comprehensive analysis involving 297 organic pollutants was conducted. Passive samplers were deployed to monitor micropollutant presence in the river. Sixty-four analytes were identified in the river flow, with telmisartan being the most prevalent. Nonaged PVC showed the highest telmisartan concentration at 279 ng/g (168 ng/m2 regarding the microplastic surface), while aged PVC exhibited a fourfold decrease. Conversely, aged LDPE preferentially adsorbed metoprolol and tramadol, with concentrations increasing 12- and 3-fold, respectively, compared to nonaged LDPE. Azithromycin and clarithromycin, positively charged compounds, exhibited higher sorption to PET microplastics, regardless of aging. Diclofenac showed higher concentrations on nonaged PVC compared to aged PVC. Aging induced structural changes in microplastics, including color alterations, smaller particle production, and increased specific surface area. These changes influenced micropollutant adsorption, with hydrophobicity, dissociation constants, and the ionic form of pollutants being key factors. Aged microplastics generally showed different sorption properties. A comparison of microplastics and control sand particles indicated preferential micropollutant sorption to microplastics, underscoring their role as vectors for contaminant transport in aquatic ecosystems. Analysis of river sediment emphasized the significance of contact time in pollutant accumulation. Overall, this study provides insights into the complex interactions between microplastics and organic pollutants under environmental conditions and contributes to a better understanding of the fate and behavior of these two types of contaminants in aquatic ecosystems.

Occurrence, bioaccumulation and trophic dynamics of per- and polyfluoroalkyl substances in two tropical freshwater lakes

We have investigated the occurrence, distribution, and biomagnification of per- and polyfluoroalkyl substances (PFAS) in two tropical lakes (Asejire and Eleyele) of Southwestern Nigeria, with contrasting urban intensities. Over an 8-month period, we sampled sediment and fish species (Clarias gariepinus: CIG; Oreochromis niloticus: ON; Coptodon guineensis: CG; Sarotherodon melanotheron: SM) across trophic levels, and analyzed various PFAS congeners, in addition to a select group of toxicological responses. While herbivores (SM) and benthic omnivores (CIG) at Asejire exhibited elevated levels of PFBS and PFOS, the pelagic omnivores (ON) showed a dominance of PFOS, PFDA, PFHxDA and EtFOSE in the muscle. At the Eleyele urban lake, PFAS patterns was dominated by PFBS, EtFOSE, PFPeS, PFOcDA and PFOS in the herbivores (SM, CG), EtFOSE, PFOS and PFBS in the pelagic omnivore (ON) and benthic omnivore (ClG). The estimated biomagnification factor (BMF) analysis for both lakes indicated trophic level increase of PFOS, PFUnA and PFDA at the suburban lake, while PFOS and EtFOSE biomagnified at the urban lake. We detected the occurrence of diSAMPAP and 9CL-PF3ONS, novel compounds not commonly reported, in PFAS studies at both lakes. The studied toxicological responses varied across trophic groups in both lakes with probable modulations by environmental conditions, trophic structure, and relative PFAS exposures in the lakes. The present study documents, for the first time in Nigeria, or any other African country, the role of urbanization on contaminant load into the environment and their implications for contaminant dynamics within the ecosystem and for aquatic food safety.

There's Something in What We Eat: An Overview on the Extraction Techniques and Chromatographic Analysis for PFAS Identification in Agri-Food Products

Per- and polyfluorinated alkyl substances (PFASs) are a group of anthropogenic chemicals used in a range of industrial processes and consumer products. Recently, their ubiquitous presence in the environment as well as their toxicological effects in humans have gained relevant attention. Although the occurrence of PFASs is widely investigated in scientific community, the standardization of analytical method for all matrices still remains an important issue. In this review, we discussed extraction and detection methods in depth to evaluate the best procedures of PFAS identification in terms of analytical parameters (e.g., limits of detection (LODs), limits of quantification (LOQs), recoveries). Extraction approaches based on liquid-liquid extraction (LLE), alkaline digestion, and solid phase extraction (SPE), followed by liquid chromatography-mass spectrometry (LC-MS) and gas chromatography-mass spectrometry (GC-MS) analysis are the main analytical methods applied in the literature. The results showed detectable recoveries of PFOA and PFOS in meat, milk, vegetables, eggs products (90.6-101.2% and of 89.2-98.4%), and fish (96-108%). Furthermore, the low LOD and LOQ values obtained for meat (0.00592-0.01907 ng g-1; 0.050 ng g-1), milk (0.003-0.009 ng g-1; 0.010-0.027 ng g-1), fruit (0.002-0.009 ng g-1; 0.006-0.024 ng g-1), and fish (0.00369-0.017.33 ng g-1; 0.05 ng g-1) also confirmed the effectiveness of the recent quick, easy, cheap, effective, rugged, and safe method (QuEChERS) for simple, speedy, and sensitive ultra-trace PFAS analysis.

A non-lethal stable isotope analysis of valued freshwater predatory fish using blood and fin tissues as alternatives to muscle tissue

Stable isotope analysis (SIA) is widely used to study trophic ecology and food webs in aquatic ecosystems. In the case of fish, muscle tissue is generally preferred for SIA, and the method is lethal in most cases. We tested whether blood and fin clips can be used as non-lethal alternatives to muscle tissue for examining the isotopic composition of two freshwater predatory fish, European catfish (Silurus glanis) and Northern pike (Esox lucius), species of high value for many freshwater systems as well as invasive species in many others. Blood samples from the caudal vein, anal fin clips, and dorsal muscle obtained by biopsy punch were collected from four catfish and pike populations (14-18 individuals per population). Subsequently, these samples were analyzed for δ13C and δ15N. The effects of alternative tissues, study site, and fish body mass on the isotopic offset were investigated. Both species showed a correlation between the isotopic offset and the tissue type, as well as the study site, but no significant relationship with the body mass. The isotopic offsets between tissues were used to calculate the conversion equations. The results demonstrated that both blood and fin clips are suitable and less invasive alternative to muscle in SIA studies focused on European catfish and Northern pike. Blood provided better correspondence to muscle isotope values. However, our results clearly demonstrated that isotopic offsets between tissues vary significantly among populations of the same species. Therefore, obtaining a muscle biopsy from several individuals in any population is advisable to gain initial insights and establish a possible population-specific inter-tissue conversion.

Structure-Related Thyroid Disrupting Effect of Perfluorooctanesulfonate-like Substances in Zebrafish Larvae

Chlorinated polyfluorooctane ether sulfonate (6:2 Cl-PFESA), hydrogenated polyfluorooctane ether sulfonate (6:2 H-PFESA), and chlorinated polyfluorooctanesulfonate (Cl-PFOS) share structural similarities with the regulated perfluorooctanesulfonate (PFOS), but their toxic potential is rarely known. Here, the thyroid disrupting potential of these four compounds in zebrafish larvae has been comparably investigated. PFOS, Cl-PFOS, and 6:2 Cl-PFESA were accumulated in the larvae at similar levels, approximately 1.3-1.6 times higher than 6:2 H-PFESA. Additionally, PFOS, Cl-PFOS, and 6:2 Cl-PFESA exhibited stronger disruption than 6:2 H-PFESA on genetic regulation, particularly concerning thyroid hormone (TH) activation and action and on TH homeostasis in both free and total forms of thyroxine (T4) and 3,5,3'-triiodothyronine (T3). These results indicate that chlorination or oxygen insertion does not substantially alter the thyrotoxicity of PFOS, but hydrogenation mitigates it. Molecular docking analysis and the luciferase reporter gene assay provided mechanistic perspectives that the PFOS-like substances could competitively replace THs to bind with TH plasma and membrane transporters, thereby disrupting TH transport and action, respectively. Moreover, they are also potent to disrupt TH synthesis and activation through Na+/K+-dependent transport of I- or competitive binding to the sites of deiodinases.

Characterizing the long-term occurrence and anthropogenic drivers of per- and polyfluoroalkyl substances in surface water of the Rhine River

Per- and polyfluoroalkyl substances (PFAS) raise significant concerns due to their persistence, bioaccumulation potential, and toxicity to both ecosystems and human health. However, the long-term trends of PFAS in aquatic environments remain inadequately explored. In this study, we systematically assessed the spatiotemporal distribution, periodic fluctuations, source apportionment, and risk evaluation of 12 PFAS in the Rhine River based on the long-term measuring data collected from 2007 to 2019. The study revealed that the mean concentration and mass flux of total PFAS during this period were 32.83 ng L-1 and 6.36 × 104 μg s-1, declining at an annual rate of 3.70% and 3.82%, respectively. Wavelet analysis demonstrated that the most prominent periodic oscillation of PFAS was 40-60 months. Regarding the sources of PFAS, we employed the self-organizing map (SOM) and the positive matrix factorization (PMF) model for source apportionment. The results indicated that the primary sources of PFAS were agrochemical, pharmaceutical and textile industries, accounting for 38.1% of the total concentration. The contribution from household contamination, tannery industry, and coating materials has increased annually. In contrast, the share of electrochemical fluorination and chemical recycling has shown a continuous decline. The risk quotient (RQ) and hazard quotient (HQ) calculations for three age groups indicated that PFAS exposure did not pose a significant risk to ecological or human health. Implementing source-oriented mitigation strategies is crucial to effectively reduce the ecological and human health risks of PFAS in receiving waters.

PFAS levels in fish species in the Po River (Italy): New generation PFAS, fish ecological traits and parasitism in the foreground

Per- and polyfluoroalkyl substances (PFAS) are resistant to breakdown and are now considered ubiquitous and concerning contaminants. Although scientific and legislative interest in these compounds has greatly increased in recent decades, our knowledge about their environmental fate and their effects on organisms is still incomplete, especially those of the new generation PFAS. In this study, we analysed the level of PFAS contamination in the fish fauna of the Po River, the most important waterway in Italy, to evaluate the influence of different factors (such as fish ecological traits and parasitism) on the accumulation of 17 PFAS. After solvent extraction and purification, hepatic or intestinal tissues from forty specimens of bleak, channel catfish, and barbel were analysed by liquid chromatography coupled with mass spectrometry (LOQ = 2.5 ng/g w.w.). The prevalent PFAS were perfluorooctane sulfonate (PFOS), present in all samples at the highest concentration (reaching a maximum of 126.4 ng/g and 114.4 ng/g in bleak and channel catfish, respectively), and long-chain perfluoroalkyl carboxylic acids (PFDA and PFUnDA). Perfluorooctanoic acid and new generation PFAS (Gen X and C6O4) were not detected. Comparison of the hepatic contamination between the benthic channel catfish and the pelagic bleak showed similar concentrations of PFOS (p > 0.05) but significantly higher concentrations of other individual PFAS and of the sum of all measured PFAS (p < 0.05) in bleak. No correlation was found between the hepatic level of PFAS and fish size in channel catfish. For the first time, PFAS partitioning in a parasite-fish system was studied: intestinal acanthocephalans accumulated PFOS at lower levels than the intestinal tissue of their host (barbel), in contrast to what has been reported for other pollutants (e.g., metals). The infection state did not significantly alter the level of PFAS accumulation in fish, and acanthocephalans do not appear to be a good bioindicator of PFAS pollution.

Vermont-wide assessment of anthropogenic background concentrations of perfluoroalkyl substances in surface soils

Shallow surface soils from 66 suburban sampling locations across Vermont were analyzed for 17 different perfluoroalkyl acids (PFAA). PFAA were detected in all 66 surface soils, with a total concentration of PFAA ranging from 540 to 36,000 ng/kg dry soil weight (dw). Despite the complexity of site-specific factors, some general trends and correlations in PFAA concentrations were observed. For instance, perfluoro-1-octanesulfonate (PFOS) dominated in all soil samples while seven other PFAA, including perfluoro-n-nonanoic acid, perfluoro-n-octanoic acid, perfluoro-n-hexanoic acid, perfluoro-n-heptanoic acid, perfluoro-n-decanoic acid, perfluoro-n-undecanoic acid, perfluoro-1-butanesulfonate, and perfluoro-1-hexanesulfonate (PFNA, PFOA, PFHxA, PFHpA, PFDA, PFUnDA, and PFBS, respectively), were identified at more than 50 % of the locations. Perfluoroalkyl carboxylic acids (PFCA) showed a positive correlation with total organic carbon, whereas no clear correlation was observed for perfluoroalkyl sulfonate acids (PFSA). In addition, variations in geographical distributions of PFAA were observed, with relatively higher total PFAA in northern regions when compared to Southern Vermont. Moreover, PFHxA, PFNA, PFDA, PFUnDA, PFOS, and total PFAA were positively correlated to land-use types in Northern Vermont. These results are useful for understanding unique behaviors of PFCA vs. PFSA in geospatially distributed surface soils and for providing anthropogenic background data for setting PFAS cleanup standards for surface soils.

Exposure to perfluoroalkyl substances and neurodevelopment in 2-year-old children: A prospective cohort study

BACKGROUND

Humans are widely exposed to per- and polyfluoroalkyl substances (PFAS). As fetal stage is a critical window for neurodevelopment, it is important to know if in utero exposure to PFAS affects fetal neurodevelopment. However, previous human studies are both limited and inconsistent.

OBJECTIVES

To investigate the relationship between PFAS exposure during early pregnancy and the neurodevelopmental status at 2 years of age in a prospective cohort study.

METHODS

We measured 10 PFAS in maternal plasma samples collected prior to 16 weeks of gestation in the Shanghai Birth Cohort Study between 2013 and 2016. Childhood neurodevelopment was assessed at 2 years of age using the Bayley Scales of Infant and Toddler Development-Third Edition (BSID-III). Associations with domain specific scores for individual PFAS were assessed by multiple linear regression and binary logistic regression when scores were dichotomized. Quantile-based g-computation was used to estimate the joint effects of PFAS mixture.

RESULTS

A total of 2257 mother-child pairs who had both PFAS and BSID measurements were included in our analyses. The means and standard deviations of comprehensive scores were 115 ± 22, 96 ± 15 and 108 ± 15 for cognition, language, and motor, respectively. In multiple linear regressions, we observed significant negative associations of perfluorooctane sulfonate (PFOS), perfluorononanoic acid (PFNA), perfluorodecanoic acid (PFDeA), perfluoroundecanoic acid (PFUnDA) with cognitive scores; PFNA, PFDeA, PFUnDA and perfluorohexanesulfonate (PFHxS) negatively with language scores; and PFNA and PFUnDA negatively with motor scores. Quantile-based g-computation showed that PFAS mixture was significantly associated with decreased cognitive and language scores, with an estimated β of -2.1 [95% confidence interval (CI): -3.5, -0.7)] and -2.0 (95% CI: -2.9, -1.0) per one quartile increase in PFAS mixture for cognitive and language domains, respectively. PFAS mixture was associated with increased odds of low cognition (adjusted odds ratio [OR] = 1.3, 95% CI:1.0, 1.6) and language scores (OR = 1.2, 95% CI: 1.1, 1.3).

CONCLUSIONS

PFAS exposure during early pregnancy was significantly associated with the adverse neurodevelopmental status at 2 years of age, which raises a serious public health concern.