Impacts of di-(2-ethylhexyl) phthalate on Folsomia candida (Collembola) assessed with a multi-biomarker approach

Integrated physiological, intestinal microbiota, and metabolomic responses of adult zebrafish (Danio rerio) to subacute exposure to antimony at environmentally relevant concentrations

The available information regarding the impact of antimony (Sb), a novel environmental pollutant, on the intestinal microbiota and host health is limited. In this study, we conducted physiological characterizations to investigate the response of adult zebrafish to different environmental concentrations (0, 30, 300, and 3000 µg/L) of Sb over a period of 14 days. Biochemical and pathological changes demonstrated that Sb effectively compromised the integrity of the intestinal physical barrier and induced inflammatory responses as well as oxidative stress. Analysis of both intestinal microbial community and metabolome revealed that exposure to 0 and 30 µg/L of Sb resulted in similar microbiota structures; however, exposure to 300 µg/L altered microbial communities' composition (e.g., a decline in genus Cetobacterium and an increase in Vibrio). Furthermore, exposure to 300 µg/L significantly decreased levels of bile acids and glycerophospholipids while triggering intestinal inflammation but activating self-protective mechanisms such as antibiotic presence. Notably, even exposure to 30 µg/L of Sb can trigger dysbiosis of intestinal microbiota and metabolites, potentially impacting fish health through the "microbiota-intestine-brain axis" and contributing to disease initiation. This study provides valuable insights into toxicity-related information concerning environmental impacts of Sb on aquatic organisms with significant implications for developing management strategies.

Evaluation of Bis(2-ethylhexyl) phthalate toxicity on the third instar larvae of transgenic Drosophila melanogaster (hsp70-lacZ) Bg9

Bis(2-ethylhexyl) phthalate, generally known as DEHP is a synthetic compound mainly used as a plasticizer to make polyvinyl chloride products flexible and soft. The present work aimed to study the toxicity of Bis(2-ethylhexyl) phthalate on the third instar larvae of transgenic Drosophila melanogaster(hsp70-lacZ) Bg9. The hsp70 gene is associated with the β-galactosidase in our present transgenic strain therefore, the more activity of β-galactosidase will indirectly correspond to hsp70 expression. The third instar larvae were allowed to feed on the diet for 24 h having 0.001, 0.005, 0.01, and 0.02 M of Bis(2-ethylhexyl) phthalate at the final concentration. After the exposure of 24hrs, the larvae were subjected to ONPG assay, X-gal staining, trypan blue exclusion test, oxidative stress markers assays, and comet assay. A dose-dependent increase in hsp70 expression, tissue damage, Glutathione-S-transferase (GST) activity, lipid peroxidation, monoamine oxidase, caspase-9 & 3, protein carbonyl content (PCC), DNA damage and decrease in the glutathione (GSH) content, delta-aminolevulinic acid dehydrogenase (ẟ-ALD-D) and acetylcholinesterase activity were observed in the larvae exposed to 0.005, 0.01, 0.02 M of Bis-(2-ethylhexyl) phthalate. The dose of 0.001 M of Bis(2-ethylhexyl) phthalate did not showed any toxic effects and hence can be considered as No Observed Adverse Effect Level (NOAEL) for Bis(2-ethylhexyl) phthalate. The study supports the use of Drosophila for the evaluation of possible toxic effects associated with synthetic compounds.

Integrated transcriptomic and biochemical characterization of the mechanisms governing stress responses in soil-dwelling invertebrate (Folsomia candida) upon exposure to dibutyl phthalate

Dibutyl phthalate (DBP) is one of the most commonly utilized plasticizers and a frequently detected phthalic acid ester (PAE) compound in soil samples. However, the toxicological effects of DBP on soil-dwelling organisms remain poorly understood. This study employed a multi-biomarker approach to investigate the impact of DBP exposure on Folsomia candida's survival, reproduction, enzyme activity levels, and transcriptional profiles. Analyses of antioxidant biomarkers, including catalase (CAT) and glutathione S-transferase (GST), as well as detoxifying enzymes such as acetylcholinesterase (AChE), Cytochrome P450 (CYP450), and lipid peroxidation (LPO), revealed significant increases in CAT activity, GST levels, and CYP450 expression following treatment with various doses of DBP for 2, 4, 7, or 14 days. Additionally, LPO induction was observed along with significant AChE inhibition. In total, 3175 differentially expressed genes (DEGs) were identified following DBP treatment that were enriched in six Gene Ontology (GO) terms and 144 Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways, including 85 upregulated and 59 downregulated primarily associated with lipid metabolism, signal transduction, DNA repair, and cell growth and death. Overall these results provide foundational insights for further research into the molecular mechanisms underlying responses of soil invertebrates to DBP exposure.

Phthalate induced hormetic effect reveals susceptibility of gill compared to muscle tissue after depuration in commercially important fish (Etroplus suratensis)

Effect of Bis-2ethylhexyl phthalate (DEHP) on commercially important tropical fish pearl spot has not been demonstrated at environmental concentrations along with depuration. The species is estuarine, juvenile and difficult to maintain but widely consumed and well distributed in tropical estuaries. Antioxidant activity of SOD, CAT and GPx was enhanced on all exposure days for gill and muscle suggesting high oxidative stress, except on day 5. Detoxifying enzyme-GST behaved differentially in gill and muscle tissue after depuration, depicting inhibited activity of GST in gill leading to lipid peroxidation. However, the muscle tissue was able to recover from stress after 7 days of depuration with the help of detoxifying enzymes. Overcompensation of antioxidant activity was observed over disruption of homeostasis defining hormesis effect. Integrated biomarker (IBR) index depicted high toxicity during entire exposure time, but after depuration, gill could not mediate LPO at lowest concentration (10 μg/l) while muscle tissue recovered, suggesting persistence of stress in gill.

DNA Damage Estimation after Chronic and Combined Exposure to Endocrine Disruptors: An In Vivo Real-Life Risk Simulation Approach

Exposure to chemical substances has always been a matter of concern for the scientific community. During the last few years, researchers have been focusing on studying the effects resulting from combined exposure to different substances. In this study, we aimed to determine the DNA damage caused after chronic and combined exposure to substances characterized as endocrine disruptors using comet and micronuclei assays, specifically glyphosate (pure and commercial form), bisphenol A, parabens (methyl-, propyl- and butylparaben), triclosan and bis (2-ethylhexyl) phthalate. The highest mean tail intensity was observed in the group exposed to a high-dose (10 × ADI) mixture of substances (Group 3), with a mean value of 11.97 (11.26-13.90), while statistically significant differences were noticed between the groups exposed to low-dose (1 × ADI) (Group 2) and high-dose (10 × ADI) (Group 3) mixtures of substances (p = 0.003), and between Group 3 and both groups exposed to high doses (10 × ADI) of the pure and commercial forms of glyphosate (Groups 4 (p = 0.014) and 5 (p = 0.007)). The micronuclei assay results were moderately correlated with the exposure period. Group 5 was the most impacted exposure group at all sampling times, with mean MN counts ranging between 28.75 ± 1.71 and 60.75 ± 1.71, followed by Group 3 (18.25 ± 1.50-45.75 ± 1.71), showing that commercial forms of glyphosate additives as well as mixtures of endocrine disruptors can enhance MN formation. All exposure groups showed statistically significant differences in micronuclei counts with an increasing time trend.

The interaction effects of biodegradable microplastics and Cd on Folsomia candida soil collembolan

In real-field soil conditions, multiple chemicals exposure may be the real scenario for soil biota. The co-occurrence of microplastics (MPs) and cadmium (Cd) is common in soils, which may pose a potential risk to soil ecosystems. Degradable microplastics are producing more MPs, and the potential effects on soil ecosystems are unknown. Therefore, a standard soil animal collembolan Folsomia candida was used to evaluate the single and interaction effects of biodegradable MPs (PLA) and Cd. The results showed that single and co-biodegradable PLA and Cd all had negative influences on the survival, reproduction, and growth of F. candida, and the effects intensified with PLA concentrations. The survival rate, reproduction rate, adult body length, and juvenile body length decreased by 20.0%, 24.2%, 22.9%, and 32.2% at MPs-100 treatment. But combined PLA and Cd alleviated the toxicity of single Cd on F. candida at lower PLA concentrations. The number of juveniles increased by 29.3%, the survival rate increased by 7.52%, the adult body length increased by 11.7%, and the juvenile body length increased by 19.0% at MPs-1 + Cd than single Cd treatment. Biochemical assays on antioxidant enzymes had the same results. Antioxidant enzymes CAT and POD were more sensitive than SOD. CAT and POD activities were induced quickly at shorter exposure periods, and MP treatment thus may be promising biomarkers on soil collembolan for soil MP exposure. PLA is degraded with time in soils; therefore, the long-term effects of co-MPs and Cd in soils are suggested to be further studied.

Microplastics are transferred by soil fauna and regulate soil function as material carriers

The ecotoxicological effects of microplastics, a new and widespread ecosystem pollutant, have been extensively reported. However, it remains unclear whether soil fauna transfer microplastics and whether migration behaviours influence subsequent ecological functions in terrestrial ecosystems. We investigated the transfer patterns of microplastics and their adsorbed substances by soil animals (the springtail, Folsomia candida) and the effect of the transfer on the decomposition of soil organic matter through a standardized cotton strip assay. The results showed that springtails had a strong ability to transfer microplastics into the soil. The adsorbed nutrient (nitrogen; N), pollutant (cadmium; Cd), and green fluorescent Escherichia coli (GFP-E. coli) were also transferred with the microplastics. In addition, cotton strip decomposition was accelerated when the microplastics adsorbed N, but the adsorption of Cd decreased decomposition. These ecological effects were particularly strong for small microplastics. Microplastic transfer regulated soil bacterial communities, promoting the growth of Ascomycota fungi and inhibiting that of Basidiomycota, leading to cotton strip decomposition. Thus, microplastic pollution may occur at one site, but microplastics can be transferred anywhere in terrestrial ecosystems by soil animals and adsorb other substances, including nutrients and pollutants, that affect ecosystem function. Therefore, more studies on the migration behaviour of microplastics are necessary.

Clay Types Modulate the Toxicity of Low Concentrated Copper Oxide Nanoparticles Toward Springtails in Artificial Test Soils

Copper oxide nanoparticles (CuO-NPs) can be applied as an efficient alternative to conventional Cu in agriculture. Negative effects of CuO-NPs on soil organisms were found, but only in clay-rich loamy soils. It is hypothesized that clay-NP interactions are the origin of the observed toxic effects. In the present study, artificial Organisation for Economic Co-operation and Development soils containing 30% of kaolin or montmorillonite as clay type were spiked with 1-32 mg Cu/kg of uncoated CuO-NPs or CuCl₂ . We performed 28-day reproduction tests with springtails of the species Folsomia candida and recorded the survival, reproduction, dry weight, and Cu content of adults. In a second experiment, molting frequency and the Cu content of exuviae, as well as the biochemical endpoints metallothionein and catalase (CAT) in springtails, were investigated. In the reproduction assay, negative effects on all endpoints were observed, but only in soils containing montmorillonite and mostly for CuO-NPs. For the biochemical endpoints and Cu content of exuviae, effects were clearly distinct between Cu forms in montmorillonite soil, but a significant reduction compared to the control was only found for CAT activity. Therefore, the reduced CAT activity in CuO-NP-montmorillonite soil might be responsible for the observed toxicity, potentially resulting from reactive oxygen species formation overloading the antioxidant system. This process seems to be highly concentration-dependent, because all endpoints investigated in reproduction and biochemical assays of CuO-NP-montmorillonite treatments showed a nonlinear dose-response relationship and were constantly reduced by approximately 40% at a field-realistic concentration of 3 mg/kg, but not at 32 mg/kg. The results underline that clay-CuO-NP interactions are crucial for their toxic behavior, especially at low, field-realistic concentrations, which should be considered for risk assessment of CuO-NPs. Environ Toxicol Chem 2022;41:2454-2465. © 2022 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC.

Nanoplastics: Status and Knowledge Gaps in the Finalization of Environmental Risk Assessments

Nanoplastics (NPs) are particles ranging in size between 1 and 1000 nm, and they are a form of environmental contaminant of great ecotoxicological concern. Although NPs are widespread across ecosystems, they have only recently garnered growing attention from both the scientific community and regulatory bodies. The present study reviews scientific literature related to the exposure and effects of NPs and identifies research gaps that impede the finalization of related environmental risk assessments (ERAs). Approximately 80 articles published between 2012 and 2021 were considered. Very few studies (eight articles) focused on the presence of NPs in biotic matrices, whereas the majority of the studies (62 articles) assessed the lethal and sublethal effects of NPs on aquatic and terrestrial organisms. Whilst many studies focused on nude NPs, only a few considered their association with different aggregates. Amongst NPs, the effects of polystyrene are the most extensively reported to date. Moreover, the effects of NPs on aquatic organisms are better characterized than those on terrestrial organisms. NP concentrations detected in water were close to or even higher than the sublethal levels for organisms. An ERA framework specifically tailored to NPs is proposed.