Toxicity of Per- and Polyfluoroalkyl Substances to Aquatic Invertebrates, Planktons, and Microorganisms

Segmentation of Renal Thyroid Follicle Colloid in Common Carp: Insights into Perfluorooctanoic Acid-Induced Morphometric Alterations

Perfluorooctanoic acid (PFOA) is a globally prevalent contaminant of concern recognised for its persistence and detrimental effects on both wildlife and humans. While PFOA has been established as a disruptor of thyroid function, limited data exist regarding its impact on thyroid morphology. The kidney of the common carp (Cyprinus carpio) harbours numerous thyroid follicles, rendering it a valuable biomarker organ for investigating PFOA-induced thyroid alterations. Renal tissue slides, stained with the Alcian blue/PAS method, were examined from carp in three experimental groups: unexposed, exposed to 200 ng L-1, and exposed to 2 mg L-1 of PFOA over 56 days. Thyroid follicle colloids were segmented, and related morphometric parameters, including perimeter, area, and shape descriptors, were obtained. Statistical analyses revealed significant reductions in thyroid follicle colloid perimeter and area in the 200 ng L-1 PFOA group compared to the unexposed and 2 mg L-1 PFOA groups. Additionally, the fish exposed to PFOA exhibited a significantly higher follicle count compared to the unexposed fish. These findings collectively suggest that PFOA induces thyroid folliculogenesis, emphasising its impact on thyroid morphology even at an environmentally relevant concentration (200 ng L-1).

PFAS in Nigeria: Identifying data gaps that hinder assessments of ecotoxicological and human health impacts

This review examines the extensive use and environmental consequences of Per- and Polyfluoroalkyl Substances (PFAS) on a global scale, specifically emphasizing their potential impact in Nigeria. Recognized for their resistance to water and oil, PFAS are under increased scrutiny for their persistent nature and possible ecotoxicological risks. Here, we consolidate existing knowledge on the ecological and human health effects of PFAS in Nigeria, focusing on their neurological effects and the risks they pose to immune system health. We seek to balance the advantages of PFAS with their potential ecological and health hazards, thereby enhancing understanding of PFAS management in Nigeria and advocating for more effective policy interventions and the creation of safer alternatives. The review concludes with several recommendations: strengthening regulatory frameworks, intensifying research into the ecological and health impacts of PFAS, developing new methodologies and longitudinal studies, fostering collaborative efforts for PFAS management, and promoting public awareness and education to support sustainable environmental practices and healthier communities in Nigeria.

Evidence on the genotoxic and ecotoxic effects of PFOA, PFOS and their mixture on human lymphocytes and bacteria

Considering that the PFOA and PFOS are widely spread chemicals with harmful effects in human and environmental health as well as the increasing interest of the scientific community in the implications that might present especially when they co-exist, this study aims to assess their harmful impacts, both individually and as a mixture on human lymphocytes and aquatic microorganisms. The cytokinesis-block micronucleus (CBMN) assay was used to examine their potential for cytotoxicity and genotoxicity towards human cells, and Microtox assay using Aliivibrio fischeri assay was used to estimate the environmental risk. Regarding the human lymphocytes, the tested concentrations ranged between 250 and 1000 μg L-1, for all cases. PFOA increased slightly the frequency of micronuclei (MN) but without statistical significance. In the case of PFOS, our results showed a dose-dependent increase in the frequency of micronuclei which showed a statistically significant difference (p < 0.001) at 1000 μg L-1, which is the highest studied concentration. Regarding the CBPI index, statistically significant (p < 0.05, p < 0.01, and p < 0.001 respectively) differences were observed at all studied concentrations of PFOS, compared to the control. The mixture was found to be more cytotoxic and genotoxic than the individual tested compounds, causing a higher decrease at the CBPI index even in lower concentrations and increase at the MN frequencies. Aliivibrio fischeri was exposed to various concentrations in the range of 0.5 μg L-1- 20 mg L-1, for 5 and 15 min and significant increase in the inhibition percentage at the highest tested concentration of their mixture after 15 min was observed.

Effects on food intake of Gammarus spp. after exposure to PFBA in very low concentrations

Per- and polyfluoroalkyl substances (PFAS) are a group of thousands of highly persistent anthropogenic chemicals widely used in many industries. Therefore, they are, ubiquitously present in various types of environments. Despite their omnipresence, ecotoxicological studies of most PFAS are scarce, and those available often assess the effects of long chain PFAS. In this study, we present the results of an exposure experiment in which wild aquatic amphipod Gammarus spp. was exposed to the short chain perfluorinated substance perfluorobutanoic acid (PFBA) at very low and environmentally relevant concentrations of 0, 10 and 100 ng/L. The exposure lasted for 12 days, and food intake and non-reproductive behavior were analyzed. Exposure to 10 and 100 ng/L PFBA resulted in a lower consumption of food during exposure but no effect on behavior was found.

Toxicity of environmentally relevant concentration of PFAS chemicals in Lumbriculus variegatus (Oligochaeta, Lumbriculidae) - A multi-bioindicator study

PFAS, or per- and polyfluoroalkyl substances, are a family of man-made chemicals found in a variety of products from non-stick cookware and food wrappers to firefighting foams. PFAS are persistent and widely distributed in the environment, including aquatic environments. In this study we examined the impact of PFAS chemicals on the physiological and behavioral endpoints of Lumbriculus variegatus (i.e., blackworms). Lumbriculus variegatus is a species of freshwater annelid worm that plays key roles in shallow freshwater ecosystems. At an environmentally relevant concentration of 1 μg/L, 12-day aqueous exposure to long chain PFAS, including PFOA, PFOS and PFDA, each markedly slowed the pulse rate of the dorsal blood vessel in L. variegatus, indicating a suppressive effect on blood circulation. The mean pulse rate was reduced from 9.6 beats/minute to 6.2 and 7.0 beats/min in PFOA and PFOS, respectively (P < 0.0001). Further, PFOA, PFOS and PFDA reduced the escape responsiveness of L. variegatus to physical stimulation. The percentage of worms showing normal escape behavior was reduced from 99.0% in control to 90.6% in the PFOS exposed group (P < 0.01). In a chronic (4 week) growth study, exposure to overlying water and sediment spiked with PFOA, PFOS or PFDA reduced the total biomass and the number of worms, indicating a suppressive effect on worm population growth. For instance, PFOA and PFDA reduced the total dry biomass by 26.3% and 28.5%, respectively, compared to the control (P < 0.05). The impact of PFAS on blackworm physiology is accompanied by an increase in lipid peroxidation. The level of malondialdehyde (MDA), an indicator of lipid peroxidation, and catalase, a major antioxidant enzyme, were markedly increased in PFOA, PFOS and PFDA exposed groups. Interestingly, exposure to PFHxA, a short chain PFAS, had no detectable effect on any of the measured endpoints. Our results demonstrate that L. variegatus is highly sensitive to the toxic impact of long chain PFAS chemicals as measured by multiple endpoints including blood circulation, behavior, and population growth. Such toxicity may have a detrimental impact on L. variegatus and the freshwater ecosystems where it resides.

Uncovering the impact of agricultural activities and urbanization on rivers from the Piracicaba, Capivari, and Jundiaí basin in São Paulo, Brazil: A survey of pesticides, hormones, pharmaceuticals, industrial chemicals, and PFAS

Rivers in Southeast Brazil are essential as sources of drinking water, energy production, irrigation, and industrial processes. The Piracicaba, Capivari, and Jundiaí rivers basin, known as the PCJ basin, comprises major cities, industrial hubs, and large agricultural areas, which have impacted the water quality in the region. Emerging contaminants such as pesticides, hormones, pharmaceuticals, industrial chemicals, and per- and polyfluoroalkyl substances (PFAS) are likely to be released into the rivers in the PCJ basin; however, the current Brazilian legislation does not require monitoring of most of these chemicals. Thus, the extent of emerging contaminants pollution and their risks to aquatic and human life in the basin are largely unknown. In this study, we investigated the occurrence of several pesticides, hormones, pharmaceuticals, and personal care products in 15 sampling points across the PCJ basin, while industrial chemicals and PFAS were assessed in 11 sampling points. The results show that agriculture and industrial activities are indeed causing the pollution of most rivers. Multivariate analysis indicates that some sampling points, such as Jundiaí, Capivari, and Piracicaba rivers, are largely impacted by pesticides used in agriculture. In addition, to the best of our knowledge, this is the first study reporting the presence of PFAS in rivers in São Paulo, the most populous state in Brazil. Four out of eight species of PFAS assessed in our study were detected in at least 5 sampling points at concentrations ranging from 2.0 to 50.0 ng L-1. The preliminary risk assessment indicates that various pesticides, caffeine, industrial chemicals, and PFAS were present at concentrations that could threaten aquatic life. Notably, risk quotients of 414, 340, and 178 were obtained for diuron, atrazine, and imidacloprid, respectively, in the Jundiaí River. Our study suggests that establishing a comprehensive monitoring program is needed to ensure the protection of aquatic life and human health.

Toxicity of Per- and Polyfluoroalkyl Substances to Nematodes

Per- and polyfluoroalkyl substances (PFASs) are a class of compounds that persist in the environment globally. Besides being transported to the soil and sediments, which act as their sinks, PFASs can be transferred to several species of higher organisms directly or via bacteria, eliciting a wide range of adverse effects. Caenorhabditis elegans has been widely used in toxicological studies and life science research owing to its numerous advantages over traditional vertebrate models; notably, C. elegans has 65% conserved human-disease-associated genes and does not require ethical approvals for experimental use. This review covers a range of topics, from reported accumulation characteristics and lethal concentrations of PFAS in C. elegans to the mechanisms underlying the toxicity of PFAS at different levels, including reproductive, developmental, cellular, neurologic, oxidative, metabolic, immune, and endocrine toxicities. Additionally, the toxicity levels of some PFAS substitutes are summarized. Lastly, we discuss the toxicological mechanisms of these PFAS substitutes and the importance and promising potential of nematodes as in vivo models for life science research, epidemiological studies (obesity, aging, and Alzheimer's disease research), and toxicological investigations of PFASs and other emerging pollutants compared with other soil animals or model organisms.

Water a major source of endocrine-disrupting chemicals: An overview on the occurrence, implications on human health and bioremediation strategies

Endocrine disrupting chemicals (EDCs) are toxic compounds that occur naturally or are the output of anthropogenic activities that negatively impact both humans and wildlife. A number of diseases are associated with these disruptors, including reproductive disorders, cardiovascular disorders, kidney disease, neurological disorders, autoimmune disorders, and cancer. Due to their integral role in pharmaceuticals and cosmetics, packaging companies, agro-industries, pesticides, and plasticizers, the scientific awareness on natural and artificial EDCs are increasing. As these xenobiotic compounds tend to bioaccumulate in body tissues and may also persist longer in the environment, the concentrations of these organic compounds may increase far from their original point of concentrations. Water remains as the major sources of how humans and animals are exposed to EDCs. However, these toxic compounds cannot be completely biodegraded nor bioremediated from the aqueous medium with conventional treatment strategies thereby requiring much more efficient strategies to combat EDC contamination. Recently, genetically engineered microorganism, genome editing, and the knowledge of protein and metabolic engineering has revolutionized the field of bioremediation thereby helping to breakdown EDCs effectively. This review shed lights on understanding the importance of aquatic mediums as a source of EDCs exposure. Furthermore, the review sheds light on the consequences of these EDCs on human health as well as highlights the importance of different remediation and bioremediation approaches. Particular attention is paid to the recent trends and perspectives in order to attain sustainable approaches to the bioremediation of EDCs. Additionally, rigorous restrictions to preclude the discharge of estrogenic chemicals into the environment should be followed in efforts to combat EDC pollution.

Persistent oxidative injury and neurobehavioral impairment in adult male and female Nauphoeta cinerea exposed to perfluorooctanoic acid

This study aimed to elucidate if the toxicity of perfluorooctanoic acid (PFOA), an emerging persistent organic contaminant, is reversible or not in adult male and female Nauphoeta cinerea. Both sexes of Nauphoeta cinerea were separately exposed to 0, 1 and 5 mg/L PFOA in drinking water for 21 consecutive days. PFOA-exposed Nauphoeta cinerea exhibited significant deficits in the locomotor and exploratory capabilities with concomitant increase in anxiogenic behaviors which persisted after cessation of PFOA exposure. Moreover, PFOA-induced decrease in acetylcholinesterase activity persisted after cessation of PFOA exposure in both insects' sexes. Catalase and superoxide dismutase activities were increased in the midgut but restored to control following cessation of PFOA exposure. The increased reactive oxygen and nitrogen species, nitric oxide and hydrogen peroxide levels persisted in the head whereas they were abated in the midgut after cessation of PFOA exposure. However, PFOA-induced persistent increase in lipid peroxidation and protein carbonyl levels in the head and midgut of insects. Collectively, PFOA exposure elicited persistent neurobehavioral and oxidative injury similarly in both sexes of adult Nauphoeta cinerea during this investigation.