The strategy for estrogen receptor mediated-risk assessment in environmental water: A combination of species sensitivity distributions and in silico approaches.

Risk assessment for molecular toxicity endpoints of environmental matrices may be a pressing issue. Here, we combined chemical analysis with species sensitivity distributions (SSD) and in silico docking for multi-species estrogen receptor mediated-risk assessment in water from Dongjiang River, China. The water contains high levels of phenolic endocrine-disrupting chemicals (PEDCs) and phthalic acid esters (PAEs). The concentration of ∑4PEDCs and ∑6PAEs ranged from 2202 to 3404 ng/L and 834-4368 ng/L, with an average of 3241 and 2215 ng/L, respectively. The SSD approach showed that 4-NP, BPA, E2 of PEDCs, and DBP, DOP, and DEHP could severely threaten the aquatic ecosystems, while most other target compounds posed low-to-medium risks. Moreover, binding affinities from molecular docking among PEDCs, PAEs, and estrogen receptors (ERα, Erß, and GPER) were applied as toxic equivalency factors. Estrogen receptor-mediated risk suggested that PEDCs were the main contributors, containing 53.37-69.79% of total risk. They potentially pose more severe estrogen-receptor toxicity to zebrafish, turtles, and frogs. ERß was the major contributor, followed by ERα and GPER. This study is the first attempt to assess the estrogen receptor-mediated risk of river water in multiple aquatic organisms. The in silico simulation approach could complement toxic effect evaluations in molecular endpoints.

Ecological and AhR-mediated risk assessment of polycyclic aromatic hydrocarbons and polybrominated diphenyl ethers on multiple aquatic species in river water: A combined chemical analysis and in silico approach.

Assessing the adverse health risks at molecular endpoints to various aquatic organisms could be an urgent issue. In this manuscript, the ecological and AhR-mediated risk of sixteen polycyclic aromatic hydrocarbons (PAHs) and six polybrominated diphenyl ethers (PBDEs) in surface water of Dongjiang River, Southern China was evaluated using chemical analysis and in silico approaches. Average concentrations of ∑16PAHs and ∑6PBDEs were 586.3 ng/L and 2.672 ng/L in the dry season (DS), and 366.8 ng/L and 2.554 ng/L in the wet season (WS). Concentrations of PAHs during the DS were significantly higher than that in the WS, while no obvious seasonal distribution was observed for PBDEs. Only Ant and BaP in all congers of PAHs posed low to medium ecological risks, and PBDEs posed a low ecological risk. Moreover, AhR-mediated risk from PAHs was two orders of magnitude higher that from PBDEs, and the AhR-mediated toxicity on frog and eel were higher than those on other aquatic organisms in Dongjiang River. Phe and BDE209 were the significant contributor to the AhR-mediated risk induced by PAHs and PBDEs, respectively. This study is the first attempt to assess AhR-mediated risk of river water in multiple aquatic organisms.

Assessment of epigenotoxic profiles of Dongjiang River: A comprehensive of chemical analysis, in vitro bioassay and in silico approach.

This research explored the occurrence, epigenetic toxic profiling and main toxic pollutants of POPs in surface water of Dongjiang River, southern China. The concentrations of selected POPs including polycyclic aromatic hydrocarbons (PAHs), endocrine disrupting chemicals (EDCs), phthalate esters (PAEs) and polybrominated diphenyl ethers (PBDEs) of surface water from 18 sites were investigated. ∑16PAHs and ∑4EDCs were at a moderate level, while ∑6PAEs and ∑6PBDEs had low pollution levels. PAHs, EDCs and PAEs showed higher concentrations in dry season than those in wet season, and the loading of selected POPs in tributaries was higher than those in mainstream due to intensive manufactures and lower runoff volume. Moreover, activities of DNA methyltransferase (DNMT)1, histone deacetylase (HDAC2, HDAC8) were confirmed to be sensitive indicators for epigenetic toxicity. The DNMT1-mediated epigenetic equivalency toxicity of organic extracts in Dongjiang River were more serious than those of HDAC2 and HDAC8. Correlation analysis shown binding affinity between POPs and DNMT1, HDAC2 and HDAC8 could be regarded as toxic equivalency factors. Risk assessment suggested that 4-nonylphenol and bisphenol A were the largest contributors to epigenetic risk. This study is the first attempt to quantify epigenetic toxicity and epigenetic risk evaluation of river water.

In situ assessment of genetic and epigenetic alterations in frog Rana plancyi and Rana limnocharis inhabiting aquatic ecosystems associated with Pb/Zn/Cu mining.

Exploration for metallic minerals leads to severe trace metal contamination, thus the ecological risk to aquatic organisms near mining regions has attracted widespread attention. In this study, two species of frog Rana plancyi and Rana limnocharis were collected as amphibian models to explore the genetic and epigenetic effects of trace metals in Dexing mining region. The results indicated that the surface water was heavily contaminated with trace metals and the two species of frog have high bioconcentration of trace metals in the liver. Trace metals disrupted the redox balance and increased reactive oxygen species levels. DNA strand breaks and increased 8-hydroxy-2'-deoxyguanosine levels were observed in the genomic DNA of frogs. Global DNA hypomethylation was found in the liver, which indicated adverse epigenetic effects on frogs. Overall, the study demonstrated that there was significant genotoxicity and epigenotoxicity of aquatic organisms living around the mining region. DNA damage and global DNA methylation are promising biomarkers for assessment of the ecological risk of trace metal pollution in aquatic amphibian frogs.

Study of nitro-polycyclic aromatic hydrocarbons in particulate matter in Dongguan.

Total suspended and size-segregated atmospheric particles were collected in four seasons at three representative points in different functional areas of Dongguan City. The detailed size distributions of six nitro-PAHs [2-nitrofluorene (2-NF), 9-nitroanthracene, 2-nitrofluoranthene (2-NFL), 3-nitrofluoranthene, 1-nitropyrene, and 2-nitropyrene (2-NP)] were determined by high-performance liquid chromatography (HPLC) with UV detection using a binary elution gradient (methanol and water). We used a toxicity assessment based on potency equivalency factors (PEFs) to estimate the inhalation risk of the particulate matter. The results showed that, aside from 2-NF and 2-NFL, the content of the other four nitro-PAHs in the microparticles (<0.4 µm) were more than 20%, a percentage significantly higher than other fractions of particulate matter. The seasonal distribution of nitro-PAHs shows that their concentrations were higher in the winter, while the PAH concentrations were higher in the summer. The study found that secondary formation (2-NFL and 2-NP) had a positive correlation with NO x and NO2, but a negative correlation with O3. The benzo[a]pyrene equivalent (BaPeq) toxicity of particulate matter in Dongguan City ranged from 0.04 to 2.63 ng m(-3), and the carcinogenic index ranged from 0.04 × 10(-6) to 2.39 × 10(-6). These values do not represent a serious threat to human health.