Recent efforts have been directed towards better understanding the persistency and toxicity of ionic liquids (ILs) in the context of the “benign-by-design” approach, but the assessment of their bioaccumulation potential remains neglected. This paper reports the experimental membrane partitioning of IL cations (imidazolium, pyridinium, pyrrolidinium, phosphonium), anions ([C(CN)3]-, [B(CN)4]-, [FSO2)2N]-, [(C2F5)3PF3]-, [(CF3SO2)2N]-) and their combinations as a measure for estimating the bioconcentration factor (BCF). Both cations and anions can have a strong affinity for phosphatidylcholine bilayers, which is mainly driven by the hydrophobicity of the ions. This affinity is often reflected in the ecotoxicological impact. Our data revealed that the bioconcentration potential of IL cations and anions is much higher than expected from octanol-water-partitioning based estimations that have recently been presented. For some ILs, the membrane-water partition coefficient reached levels corresponding to BCFs that might become relevant in terms of the “B” (bioaccumulation potential) classification under REACH. However, this preliminary estimation need to be confirmed by in vivo bioconcentration studies.

Beach environments are known to be conducive to fragmentation of plastic debris, and highly fragmented plastic particles can interact with smaller organisms. Even through stranded plastic debris may not interact directly with marine organisms, backwash processes may transport this debris back to coastal waters, where it may affect a wide range of marine life at different trophic levels. This study analysed the size distribution of stranded plastic debris (<10 mm) collected from eight coastal beaches in Guangdong Province, China. Polystyrene (PS) foams and fragments smaller than 7 mm were increasingly abundant in the smaller size classes, whereas resin pellets remained in their production sizes (∼3 mm). Microplastics (<5 mm) accounted for over 98% of the total plastic debris by abundance and 71% by weight, indicating that the plastic debris on these coastal beaches was highly fragmented and the majority of the plastic masses belonged to the microplastic size range. The observed size distributions of PS foams and fragments are believed to result from continued fragmentation. Previous studies found that the residence time of beached debris was less than one year on average, and no sign of plastic accumulation with depth in beach sediment was observed. Therefore, coastal beaches may represent a reservoir of highly fragmented and degraded microplastics that may be mobilised and returned to the sea during storm events. Further research on the dynamics and longevity of microplastics on beaches will help reveal the mass balance of microplastics on the shoreline and determine whether shorelines are sinks or sources of microplastics.

While the exposure assessment of polychlorinated dibenzo-p-dioxin and polychlorinated dibenzofuran (PCDD/Fs) for people living in the vicinity of municipal solid waste incinerators (MSWI) has been investigated, indirect exposure to MSWI-emitted PCDD/Fs via consumption of local foods has not been well assessed. In this study, the PCDD/F concentration in the local vegetables grown near a MSWI located in Shenzhen, South China, was determined to be 0.92 ± 0.59 pg/g wet weight (ww), significantly higher than that (0.25 ± 0.35 pg/g ww) in commercial vegetables (p < 0.05). The PCDD/F concentrations in Banyan leaf (Ficus microcarpa) samples collected from 5 sampling sites at 1 km intervals from the MSWI were found to be significantly decreased with increasing distance, suggesting that the local plants would be impacted by emissions from the MSWI. The exposure assessment of PCDD/Fs for the population living in the vicinity of MSWI was carried out by simultaneously analyzing PCDD/Fs in other food groups that were commonly consumed by the residents. If only the local vegetables were consumed and other foods were acquired commercially, the total dietary intake for a general adult was 0.94 ± 0.41 pg TEQ/kg bw/day, of which consumption of local vegetables accounted for 52.3%. If all foods consumed including vegetables were from a commercial source, the total dietary intake was 0.56 ± 0.30 pg TEQ/kg bw/day, of which consumption of commercial vegetables accounted for 20.1%. The present study for the first time reported the additional human exposure to PCDD/Fs via consumption of local vegetables impacted by emissions from MSWI.

Microcystin-LR is the most poisonous and commonly encountered hepatotoxin produced by cyanobacteria in an aquatic ecosystem, and it may cause thyroid dysfunction in fish. The present study aimed to reveal the effects of transgenerational toxicity of MCLR on the thyroid endocrine system under sub-chronic exposure conditions. Adult zebrafish (F0) were exposed to environmentally relevant concentrations (1, 5 and 25 μg/L) of MCLR for 45 days. The produced F1 embryos were then tested without further MCLR treatment. In the F0 generation, exposure to 25 μg/L MCLR reduced thyroxine (T4) but not 3, 5, 3′-triiodothyronine (T3) levels in females, while the T4 and T3 levels were unchanged in males. After parental exposure to MCLR, we observed a decreased hatching and growth retardation correlated with reduced thyroid hormone levels in the F1 offspring. The gene transcription and protein expression along the hypothalamic-pituitary-thyroid axis were detected to further investigate the possible mechanisms of MCLR-induced thyroid disruption. Our results indicated MCLR could disturb the thyroid endocrine system under environmentally relevant concentrations and the disrupting effects could be remarkably transmitted to its F1 offspring. We regard these adverse effects as a parental transgenerational toxicity of MCLR.

Mercury is a toxic compound to which humans are exposed by consumption of fish. Current fish consumption advisories focus on minimizing the risk posed by the species that are most likely to have high levels of mercury. Less accounted for is the variation within species, and the potential role of the geographic origin of a fish in determining its mercury level. Here we surveyed the mercury levels in 117 yellowfin tuna caught from 12 different locations worldwide. Our results indicated significant variation in yellowfin tuna methylmercury load, with levels that ranged from 0.03 to 0.82 μg/g wet weight across individual fish. Mean mercury levels were only weakly associated with fish size (R2 < 0.1461) or lipid content (R2 < 0.00007) but varied significantly, by a factor of 8, between sites. The results indicate that the geographic origin of fish can govern mercury load, and argue for better traceability of fish to improve the accuracy of exposure risk predictions.

Chemical contamination of aquatic systems often co-occurs with dramatic changes in surrounding terrestrial vegetation. Plant leaf litter serves as a crucial resource input to many freshwater systems, and changes in litter species composition can alter the attributes of freshwater communities. However, little is known how variation in litter inputs interacts with chemical contaminants. We investigated the ecological effects resulting from changes in tree leaf litter inputs to freshwater communities, and how those changes might interact with the timing of insecticide contamination. Using the common insecticide malathion, we hypothesized that inputs of nutrient-rich and labile leaf litter (e.g., elm [Ulmus spp.] or maple [Acer spp.]) would reduce the negative effects of insecticides on wetland communities relative to inputs of recalcitrant litter (e.g., oak [Quercus spp.]). We exposed artificial wetland communities to a factorial combination of three litter species treatments (elm, maple, and oak) and four insecticide treatments (no insecticide, small weekly doses of 10 μg L−1, and either early or late large doses of 50 μg L−1). Communities consisted of microbes, algae, snails, amphipods, zooplankton, and two species of tadpoles. After two months, we found that maple and elm litter generally induced greater primary and secondary production. Insecticides induced a reduction in the abundance of amphipods and some zooplankton species, and increased phytoplankton. In addition, we found interactive effects of litter species and insecticide treatments on amphibian responses, although specific effects depended on application regime. Specifically, with the addition of insecticide, elm and maple litter induced a reduction in gray tree frog survival, oak and elm litter delayed tree frog metamorphosis, and oak and maple litter reduced green frog tadpole mass. Our results suggest that attention to local forest composition, as well as the timing of pesticide application might help ameliorate the harmful effects of pesticides observed in freshwater systems.

The complex QDs-Indolicidin (QDs-Ind) has been previously shown to be a good antimicrobial system with a low acute toxicity on Daphnia magna (D. magna). However, multigenerational effects caused by exposure to QDs-Ind and after subsequent recovery are still unknown. In this study, we performed multigenerational exposure tests and we evaluated individual fitness, population growth, DNA alteration, expression of Dhb (haemoglobin), Vtg (vitellogenin), CYP4 (cytochrome P450s CYP4 family), and CYP314 (cytochrome P450s mitochondrial family 314) genes on three generation of D. magna. Results showed that the total amount of eggs produced per female and total number of brood per female and body lengths were significantly decreased, Dhb, CYP4 were upregulated while Vtg was down-regulated except at reproduction days when it was slightly up-regulated under QDs-Ind exposure. Random Amplification of Polymorphic DNA (RAPD) method has proven to be useful to qualitative assess of DNA damage during generation and to underline modification in somatic or germinal cells. The results of the study suggest that effects of chronic exposure cannot be ignored.

Reactive nitrogen (Nr) is an important driver of global change, causing alterations in ecosystem biodiversity and functionality. Environmental assessments require monitoring the emission and deposition of both the amount and types of Nr. This is especially important in heterogeneous landscapes, as different land-cover types emit particular forms of Nr to the atmosphere, which can impact ecosystems distinctively. Such assessments require high spatial resolution maps that also integrate temporal variations, and can only be feasibly achieved by using ecological indicators. Our aim was to rank land-cover types according to the amount and form of emitted atmospheric Nr in a complex landscape with multiple sources of N. To do so, we measured and mapped nitrogen concentration and isotopic composition in lichen thalli, which we then related to land-cover data. Results suggested that, at the landscape scale, intensive agriculture and urban areas were the most important sources of Nr to the atmosphere. Additionally, the ocean greatly influences Nr in land, by providing air with low Nr concentration and a unique isotopic composition. These results have important consequences for managing air pollution at the regional level, as they provide critical information for modeling Nr emission and deposition across regional as well as continental scales.

Exposure to lead(Pb) or cadmium(Cd) has been related to decreasing thyroxine in many previous studies. The underlying mechanisms have not been clarified. Heavy metal-induced thyroid autoimmunity in pregnant women has been found, despite having been rarely explored in the general population.We aimed to determine whether the blood levels of lead(BPb) or cadmium(BCd) related to the levels of sera antibodies to thyroid proteins and thyroid dysfunction in the general population.Our study included 5628 Chinese adults and was based on the 2014 SPECT-China study. Thyroid dysfunction and subclinical thyroid dysfunction were defined by total triiodothyronine (TT3), total thyroxine(TT4) and thyroid stimulating hormone (TSH).Thyroid peroxidase antibody (TPOAb), thyroglobulin antibodies (TGAb), TT3, TT4, and TSH were measured by immunochemiluminometric assays. BPb and BCd levels were tested by atomic absorption spectrometry. Linear and logistic regression models were used to analyze the associations.After adjustment for age, body mass index, smoking status (men only) and drinking status, the natural log(ln) BPb was positively related to the lnTPOAb (B = 0.062, P < 0.05) and to the lnTSH (B = 0.047, P < 0.01) in women. The lnBCd in women was positively related to the lnTGAb (B = 0.046, P < 0.05). In the adjusted logistic regression models, the BCd of women was positively related to their hypothyroid status and TGAb tertiles. The ORs of women in the middle and higher TPOAb tertiles were 1.38 (P < 0.001) and 1.35 (P < 0.001) times greater for every ln-unit increase in BPb, respectively. In men, no continuous correlation was found among variables.In women, BPb and BCd levels were related to higher TSH and hypothyroid status, respectively, suggesting a Pb and Cd induction of sex-biased thyroid autoimmunity.

Benzotriazole (BT) and its associated derivatives are used ubiquitously in industrial processes, and can be detected in indoor temperature coolants and in chemicals designed to inhibit corrosion. This chemical has been widely detected in aquatic environments and shows some degree of environmental persistence. Evidence has shown that BT exposure can negatively affect endocrine systems and can result in neurotoxicity in fish. However, no study has examined whether this chemical exhibits hepatotoxicity in fish, and if so, what are the underlying mechanism associated with the damage. To address this knowledge gap, we measured the liver proteome of adult male Chinese rare minnow (Gobiocypris rarus) exposed to either 0.05, 0.5, or 5 mg/L BT for 28 days. Overall, 17 proteins were induced and 9 were reduced in abundance following BT treatment (ratio > 1.5, p < 0.05). Pathway analysis revealed that cellular processes affected by BT included xenobiotic clearance, oxidative stress response, apoptosis, and translation. Moreover, transcripts related to these toxic pathways were also significantly affected by BT. In addition, rare minnows exposed to BT showed signs of hypertrophy of hepatocytes, nuclei pyknosis, and higher levels of cellular vacuolization compared to the controls, thus these early proteomic responses in the liver may be related to pathology (i.e. adverse outcome pathway). Our data demonstrate that BT dysregulates molecular responses in the liver and tissue pathology indicative of damage. This study provides new insight into BT hepatotoxicity in Chinese rare minnow.