Occurrence and biomagnification of perfluoroalkyl substances (PFAS) in Lake Michigan fishes

Effects of perfluorooctanoic acid on the nutritional quality of Mytilus edulis

Perfluorooctanoic acid (PFOA), which widely presents in marine environment, may produce some adverse effects to aquatic organism. Mytilus edulis are popular due to their high protein and low fat content in China. However, few studies have investigated the effects of PFOA on the quality of aquatic products. Here, PFOA effects on basic nutritional indices in M. edulis were measured, and possible mechanisms were explored. PFOA caused clear variation in physiological and biochemical indices of M. edulis. The contents of some important proteins, nutrients, and amino acids etc. dropped. Integrating metabolomics data, we speculate PFOA exposure triggered inflammation and oxidative stress in mussels, interfered with the metabolic pathways related to the quality and the transport and absorption pathways of metal ions, and affected the levels of some important elements and metabolites, thus decreasing the nutritional quality of M. edulis. The study provides new insights into PFOA adverse effects to marine organism, and may offer some references for some researchers to assess food quality and ecological risk to pollutants.

Effects of developmental exposure to individual and combined PFAS on development and behavioral stress responses in larval zebrafish

Per- and polyfluoroalkyl substances (PFAS) are a class of synthetic chemicals known for their widespread use and persistence in the environment. Laboratory and epidemiological studies investigating these compounds have signaled their neurotoxic and endocrine-disrupting propensities, prompting further research into their effects on behavioral stress responses and their potential role as risk factors for stress-related disorders such as anxiety and depression. This study elucidates the ramifications of early developmental exposures to individual and combined PFAS on the development and behavioral stress responses of larval zebrafish (Danio rerio), an established model in toxicological research. Wild-type zebrafish embryos were enzymatically dechorionated and exposed to PFOS, PFOA, PFHxS, and PFHxA between 6 and 120 h post-fertilization (hpf). We targeted environmentally relevant concentrations stemming from the USEPA 2016 Hazard Advisory Limit (HAL, 0.07 μg/L) and folds higher (0.35, 0.7, 1.75, and 3.5 μg/L). Evaluations at 120 hpf encompassed mortality, overall development, developmental defects, and larval activity both at baseline stress levels and following exposure to acute stressors (acoustic and visual). Larval exposure to PFOA, PFOS, or PFHxS (0.07 μg/L or higher) elicited significant increases in mortality rates, which capped at 23.1%. Exposure to individual chemicals resulted in limited effects on overall development but increased the prevalence of developmental defects in the body axis, swim bladder, pigmentation, and eyes, as well as the prevalence of yolk sac and pericardial edemas. Larval activity at baseline stress levels and following exposure to acute stimuli was significantly altered. Combined exposure to all four chemicals intensified the breadth of developmental and behavioral alterations, suggesting possible additive or synergistic effects. Our findings shed light on the developmental and neurobehavioral disturbances associated with developmental exposure to PFAS at environmentally relevant concentrations, the added risks of combined exposures to these chemicals, and their possible role as environmental risk factors for stress-related disorders.

Mixture Effects of Per- and Polyfluoroalkyl Substances on Embryonic and Larval Sheepshead Minnows (Cyprinodon variegatus)

Per- and polyfluoroalkyl substances (PFAS) are ubiquitous and persistent environmental contaminants originating from many everyday products. Perfluorooctane sulfonic acid (PFOS) and perfluorooctanoic acid (PFOA) are two PFAS that are commonly found at high concentrations in aquatic environments. Both chemicals have previously been shown to be toxic to fish, as well as having complex and largely uncharacterized mixture effects. However, limited information is available on marine and estuarine species. In this study, embryonic and larval sheepshead minnows (Cyprinodon variegatus) were exposed to several PFAS mixtures to assess lethal and sublethal effects. PFOS alone was acutely toxic to larvae, with a 96 h LC50 of 1.97 mg/L (1.64-2.16). PFOS + PFOA resulted in a larval LC50 of 3.10 (2.62-3.79) mg/L, suggesting an antagonistic effect. These observations were supported by significant reductions in malondialdehyde (105% ± 3.25) and increases in reduced glutathione concentrations (43.8% ± 1.78) in PFOS + PFOA exposures compared to PFOS-only treatments, indicating reduced oxidative stress. While PFOA reduced PFOS-induced mortality (97.0% ± 3.03), perfluorohexanoic acid (PFHxA) and perfluorobutanoic acid (PFBA) did not. PFOS alone did not affect expression of peroxisome proliferator-activated receptor alpha (pparα) but significantly upregulated apolipoprotein A4 (apoa4) (112.4% ± 17.8), a downstream product of pparα, while none of the other individually tested PFAS affected apoa4 expression. These findings suggest that there are antagonistic interactions between PFOA and PFOS that may reduce mixture toxicity in larval sheepshead minnows through reduced oxidative stress. Elucidating mechanisms of toxicity and interactions between PFAS will aid environmental regulation and management of these ubiquitous pollutants.

Parabens and their metabolite in a marine benthic-dominated food web from the Beibu gulf, South China Sea: Occurrence, trophic transfer and health risk assessment

Parabens are of particular concern due to their ubiquity in aquatic environments and endocrine-disrupting effects. However, information on their bioaccumulation and trophic magnification is limited. In the present study, we performed a comprehensive survey to investigate the occurrence, bioaccumulation and trophic magnification of parabens and their metabolite 4-hydroxybenzoic acid (4-HB) in a marine food web from the Beibu Gulf, South China Sea. Results showed that methylparaben (MeP) and 4-HB were the predominant target pollutants in marine organisms, with their concentrations being in the range of 0.18-13.77 and 13.48-222.24 ng/g wet weight, respectively. The bioaccumulation factors (BAFs) for target analytes were all lower than 5000, suggesting negligible bioaccumulation. However, the biota-sediment accumulation factors (BSAFs) for MeP and 4-HB were 4.51 and 3.21, respectively, which indicates significant bioaccumulation from the sediment. Furthermore, the estimated trophic magnification factor (TMF) was 2.88 for MeP, suggesting its biomagnification along the food web. In contrast, a lower TMF of 0.45 was found for 4-HB, suggesting trophic dilution along the food web. The hazard quotients (HQs) for parabens were far less than 1 in all organisms, suggesting low risks for humans through consuming marine organisms from the Beibu Gulf. This study provides substantial data on the fate and trophic transfer of parabens in a subtropical marine ecosystem.

Characterizing the Movement of Per- and Polyfluoroalkyl Substances in an Avian Aquatic-Terrestrial Food Web

The movement of per- and polyfluoroalkyl substances (PFAS) through linked aquatic-terrestrial food webs is not well understood. Tree swallows (Tachycineta bicolor) in such systems may be exposed to PFAS from multiple abiotic and/or biotic compartments. We show from fatty acid signatures and carbon stable isotopes that tree swallow nestlings in southwestern Ontario fed on both terrestrial and aquatic macroinvertebrates. The PFAS profiles of air, terrestrial invertebrates, and swallows were dominated by perfluorooctanesulfonic acid (PFOS). Short-chain perfluoroalkyl acids (PFAAs) were largely restricted to air, surface water, and sediment, and long-chain PFAAs were mainly found in aquatic invertebrates and tree swallows. PFOS, multiple long-chain perfluorocarboxylic acids [perfluorononanoic acid (PFNA), perfluorodecanoic acid (PFDA), perfluorotridecanoic acid (PFTrDA)] and perfluorooctane sulfonamide precursors were estimated to bioaccumulate from air to tree swallows. PFOS bioaccumulated from air to terrestrial invertebrates, and PFOS, PFDA, and perfluorooctane sulfonamidoacetic acids (FOSAAs) bioaccumulated from water to aquatic invertebrates. PFOS showed biomagnification from both terrestrial and aquatic invertebrates to tree swallows, and PFDA and FOSAAs were also biomagnified from aquatic invertebrates to tree swallows. The movement of PFAS through aquatic-terrestrial food webs appears congener- and compartment-specific, challenging the understanding of PFAS exposure routes for multiple species involved in these food webs.