Antibiotics in the environment usually co-exist with their transformation products with retained toxicity, raising concerns about environmental risks of their combined exposure. Herein, we reported a novel predictive approach for evaluating the individual and combined toxicity for photodegradation products of fluoroquinolone antibiotics (FQs). Quantitative structure-activity relationship (QSAR) models with promising predictive performance were constructed and validated using experimental data obtained with 13 FQs and 78 mixtures towards E. coli. A structural descriptor reflecting the interaction among FQ molecules and the target protein was employed in the QSAR models, which was obtained through molecular docking and thus provided a rational mechanistic explanation for these models. The predicted results indicated that the degradation products displayed varying degrees of changes compared to the parent FQs, while the combined toxicity of FQs and their degradation products was mostly additive. Furthermore, following UV irradiation the degradation products displayed elevated capacity of inducing resistance mutations in E. coli, though their overall toxicity was reduced. This result highlights the implications of antibiotic degradation products on resistance development in bacteria and stresses the importance of considering such impacts during environmental risk assessments of antibiotics.

The occurrence of emergent contaminants, 24 polybrominated diphenyl ethers (PBDEs), di(2-ethylhexyl)phthalate (DEHP), dibutyl phthalate (DBP), butyl benzyl phthalate (BBP), diethyl phthalate (DEP), dimethyl phthalate (DMP), di-n-octyl phthalate (DnOP), bisphenol A (BPA) and nonylphenol (NP), was investigated in sediments and fishes collected from the Tamsui River system to determine the factors that influence their distribution and their risk to aquatic ecosystems and human health. The concentrations of total PBDEs, DEHP, DBP, BBP, DEP, DMP, DnOP, BPA and NP in sediments were 1–955, ND-23570, <50–411, <50–430, ND-80, ND-<50, ND-<50, 1–144, 3–19624 μg/kg dw, respectively. The spatial-temporal distribution trends of these compounds in sediments could be attributed to urbanization, industrial discharge and effluents from wastewater treatment plants. The PBDE congener distribution patterns (BDE-209 was the dominant congener) in sediments reflected the occurrence of debromination of BDE-209 and the elution of penta-BDE from the treated products. The concentrations of total PBDEs, DEHP, DBP, BBP, DEP, DMP, DnOP, BPA and NP in fish muscles were 2–66, 17–1046, <10–231, <10–66, <30, ND-<30, ND-<30, 0.4–7 and 3–440 μg/kg ww, respectively. The species-specific bioaccumulation of these compounds by fish was found and four species particularly showed high bioaccumulation potential. BDE-47 was the predominant BDE congener in fish muscles, suggesting high bioavailability and bioaccumulation of this compound. The results of biota–sediment accumulation factors showed that BDE-47, 99, 100, 153 and 154 had relatively high bioavailability and bioaccumulation potential for some fish species. The ecological risk assessment showed that the concentrations of BPA and NP in sediments were likely to have adverse effects on aquatic organisms (risk quotients > 1). The human health risk assessment according to hazard quotients (HQs) and carcinogenic risks (CRs) revealed no remarkable risk to human health through consumption of fish contaminated with BDE-47, 99, 100, 154, 209, DEHP, BPA and NP.

Composting is a solid waste management alternative that avoids the emission of methane associated with its disposal in landfill and reduces or eliminates the need for chemical fertilisers if compost is applied. The main objective of this study was to analyse the environmental burdens of composting as a way to achieve a more circular valorisation of wine waste. To do so, with the purpose of identifying optimal operational conditions and determining the “hotspots” of the process, the life cycle assessment (LCA) methodology was used. The consumption of diesel fuel in machinery was determined to be the main critical point in the environmental effects of the system, followed by the transport and distribution of the compost. After the application of compost instead of mineral fertilisers, corn, tomato and strawberry crops would have a better environmental performance in most impact categories. In this sense, a maximum improvement of 65% in terrestrial ecotoxicity is achieved in strawberry cultivation. In light of the results obtained, it is demonstrated that composting is a suitable way of organic waste valorisation according to Circular Economy principles.

In ecological risk assessment, acute to chronic ratio (ACR) uncertainty factors are routinely applied to acute mortality benchmarks to estimate chronic toxicity thresholds. To investigate variability of aquatic ACRs, we first compiled and compared 56 and 150 pairs of acute and subchronic/chronic growth/reproductive toxicity data for fishes (Pimephales promelas (53), Danio rerio (2), and Oryzias latipes (1)) and the crustacean Daphnia magna, respectively, for 172 chemicals with different modes of action (MOA). We found that there were only significant relationships between P. promelas acute median lethal concentrations and growth lowest-observed effect concentrations for class 1 (nonpolar narcosis) chemicals, though significant relationships were demonstrated for D. magna to all Verhaar et al. MOA classes (Class 1: nonpolar narcosis, Class 2: polar narcosis, Class 3: reactive chemicals, and Class 4: AChE inhibitors and estrogenics). Probabilistic ecological hazard assessment using chemical toxicity distributions was subsequently employed for each MOA class to estimate acute and chronic thresholds, respectively, to identify MOA and species specific ecological thresholds of toxicological concern. Finally, novel MOA and species specific ACRs using both chemical toxicity distribution comparison and individual ACR probability distribution approaches were identified using representative MOA and chemical categories. Our data-driven approaches and newly identified ACR values represent robust alternatives to application of default ACR values, and can also support future research and risk assessment and management activities for other chemical classes when toxicity information is limited for chemicals with specific MOAs within invertebrates and fish.

The occurrence, distribution, and ecological risk of 10 quinolones (QNs) were investigated in the water and sediment samples from Baiyangdian Lake, China. The field samplings were conducted in April (dry season) and August (wet season) 2018, the results showed that QNs was extensively distributed in the Baiyangdian Lake. For the occurrence, Flumequine (FLU) and Ofloxacin (OFL) were the most detected QNs in Baiyangdian Lake. For the temporal variation, the sum concentration of QNs in water and sediment were ranged from 153 ng/L to 3093 ng/L and from 40.1 ng/g to 1475 ng/g in April, while ranged from 3.83 ng/L to 769 ng/L and from 20.3 ng/g to 373 ng/g in August. For the spatial variation, all of QNs exhibited significance difference in concentration at different sampling areas. Furthermore, PNEC plays an important role in ecological risk assessment, thus the PNECs of FLU and OFL were derived by assessment factors (AF), species sensitivity distribution (SSD), and AQUATOX model methods. The results showed that: PNECAFs, PNECSSDs, and PNECAQUATOXs were 18.7 μg/L, 196 μg/L, and 128 μg/L for FLU, respectively; and were 0.021 μg/L, 4.40 μg/L, and 3.00 μg/L for OFL, respectively. The PNECs for FLU and OFL derived by three approaches showed the rank of: PNECSSDs > PNECAQUATOXs > PNECAFs; while the risk quotients (RQs) followed the other rank of: RQSSDs < RQAQUATOXs < RQAFs. The results was indicated that the indirect ecological effects plays an important role in the derived PNECs for QNs, without considering the indirect ecological effects in natural ecosystem can lead to under-protective or over-protective PNECs (RQs) for chemicals. Therefore, AQUATOX model can be applied in deriving PNECs during the ecological risk assessment.

Although the coexistence of heavy metals and environmental hormones always occur in aquatic environment, the information of the combined impacts remains unclear. To explore the multi-generational toxicity of cadmium (Cd) and tributyltin (TBT), adult zebrafish (Danio rerio) (F0) were exposed to different treated groups (100 ng/l Cd, 100 ng/l TBT and their mixture) for 90 d, with their offspring (F1 and F2) subsequently reared in the same exposure solutions corresponding to their parents. Both developmental neurotoxicity and thyroid disturbances were examined in the three (F0, F1, and F2) generations. Our results showed that co-exposure to Cd and TBT induced the developmental neurotoxicity in F1 and F2 generations, reflected by the significant lower levels of neurotransmitters (dopamine and serotonin) and the inhibited acetylcholinesterase (AChE) activities. And the thyroid endocrine disruption were observed in the two-generations larval offspring by parental exposure to Cd and/or TBT, including the significantly decreasing levels of thyroid hormones and the down-regulated the expression of genes involved in the hypothalamus-pituitary-thyroid axis, compared to the control. Additional, the embryonic toxicity and growth inhibition were also determined in the fish larvae. Overall, this study examined the impacts of parental co-exposure to Cd and TBT, with regard to developmental inhibition, nervous system damage and endocrine disruption, which highlighted that co-exposure influences are complicated and need to be considered for accurate environmental risk assessment.

Water pollution by pesticides used in agriculture is currently a major concern both in Spain and in Europe as a whole, prompting the need to evaluate water quality and ecological risk in areas of intensive agriculture. This study involved monitoring pesticide residues and certain degradation products in surface and ground waters of the Denomination of Origin (DO) Jumilla vineyard area in Spain. Sixty-nine pesticides were selected and evaluated at twenty-one sampling points using a multi-residue analytical method, based on solid-phase extraction (SPE) and analysis by liquid chromatography coupled with mass spectrometry (LC-MS), providing reliable results. Twenty-six compounds from those selected were detected in the samples analyzed (eleven insecticides including one degradation product, nine herbicides, and six fungicides) and fifteen of them were found in concentrations over 0.1 μg L⁻¹ (upper threshold established by the EU for pesticides detected in waters for human consumption). Indoxacarb was present in more than 70% of the samples, being the most frequently detected compound in water samples. Some pesticides were ubiquitous in all the water samples. Ecotoxicological risk indicators, toxic units (TUs) and risk quotients (RQs), for algae, Daphnia magna and fish were calculated to estimate the environmental risk of the presence of pesticides in waters. The compounds with the highest risk were the herbicides pendimethalin, with RQ values > 1 for the three aquatic organisms, and diflufenican, posing a high risk for algae and fish, and the insecticide chlorpyrifos, with a high risk for Daphnia magna and fish. The ∑TUi determined for water at each sampling point posed only a high risk for the three aquatic organisms in a sample. These results are important for considering the selection of pesticides with less environmental risk in intensive agricultural areas.

Analysis of the transcriptome of organisms exposed to toxicants offers new insights for ecotoxicology, but further research is needed to enhance interpretation of results and effectively incorporate them into useful environmental risk assessments. Factors that must be clarified to improve use of transcriptomics include assessment of the effect of organism sex within the context of toxicant exposure. Amphipods are well recognized as model organisms for toxicity evaluation because of their sensitivity and amenability to laboratory conditions. To investigate whether response to metals in crustaceans differs according to sex we analyzed the amphipod Parhyale hawaiensis after exposure to AgCl and Ag nanoparticles (AgNP) via contaminated food. Gene specific analysis and whole genome transcriptional profile of male and female organisms were performed by both RT-qPCR and RNA-seq. We observed that expression of transcripts of genes glutathione transferase (GST) did not differ among AgCl and AgNP treatments. Significant differences between males and females were observed after exposure to AgCl and AgNP. Males presented twice the number of differentially expressed genes in comparison to females, and more differentially expressed were observed after exposure to AgNP than AgCl treatments in both sexes. The genes that had the greatest change in expression relative to control were those genes related to peptidase and catalytic activity and chitin and carbohydrate metabolic processes. Our study is the first to demonstrate sex specific differences in the transcriptomes of amphipods upon exposure to toxicants and emphasizes the importance of considering gender in ecotoxicology.

Ecological risk assessment associated with seawater intrusions has been supported on the determination of lethal/sublethal effects following standard protocols that force exposure neglecting the ability of mobile organisms to spatially avoid salinized environments. Thus, this work aimed at assessing active emigration from climate change-caused seawater intrusion into freshwater habitats. To specific objectives were delineated: first, to compute median 12-h avoidance conductivities (AC₅₀,₁₂ₕ) for freshwater species, and second, to compare it with literature data (LC₅₀,₄₈ ₒᵣ ₉₆ₕ, EC₅₀,₆ ₒᵣ ₂₁d) to assess the relevance of the inclusion of stressor-driven emigration into risk assessment frameworks. Four standard test species, representing a broad range of ecological niches – Daphnia magna, Heterocypris incongruens, Danio rerio and Xenopus laevis – were selected. The salt NaCl was used as a surrogate of natural seawater to create the saline gradient, which was established in a 7-compartment system.At each specific LC₅₀, ₄₈ ₒᵣ ₉₆ₕ, the proportion of avoiders were well above 50%, ranging from 71 to 94%. At each LC₅₀, considering also avoiders, populations would decline by 85–97%. Furthermore, for D. magna and X. laevis it was noticed that at the lowest conductivities eliciting mortality, the avoidance already exceeded 50%.The results showed that the emigration from salinity-disturbed habitats exists and that can even be more sensitive than standard endpoints. Looking solely to standard endpoints involving forced exposure may greatly underestimate the risk of local population extinction, because habitat function can be severely disrupted, with subsequent stressor-driven emigration, before any adverse physiological effects at the organism level. Thus, the present study highlights the need to include non-forced exposure testing into ecological risk assessment, namely of salinity-menaced costal freshwaters.

Propylparaben is widely used as a preservative in pharmaceuticals and personal care products and is ultimately excreted by the human body. Thus, propylparaben reaches sewage and enters the soil environment by sludge fertilization and wastewater irrigation. However, there are few existing studies on the toxicity and risks of such chemicals in terrestrial environments. In this study, a multispecies bioassay for propylparaben was performed and protective concentrations (PCs) were derived based on toxicity values by probabilistic ecological risk assessment. Acute and chronic bioassays were conducted on 11 species in eight taxonomic groups (Magnoliopsida, Liliopsida, Clitellata, Entognatha, Entomobryomorpha, Chromadorea, Chlorophyceae, Trebouxiophyceae). Based on the toxicity values calculated, the PC₉₅ values for acute and chronic SSDs were 13 and 6 mg/kg dry soil, respectively. Toxicity varied among taxa, with soil algae emerging as the most sensitive to propylparaben. This may be attributable to differences in exposure pathways among species. The exposure pathway of propylparaben can be altered by adsorption to soil particles. As parabens are presently under-regulated globally in terms of their environmental effects, our findings can serve as the basis to propose standard values for environmental protection.