Dietary Exposure to Environmentally Relevant Levels of Chemical Contaminants Reduces Growth and Survival in Juvenile Chinook Salmon.

Chemical pollution can degrade aquatic ecosystems. Chinook salmon in contaminated habitats are vulnerable to health impacts from toxic exposures. Few studies have been conducted on adverse health outcomes associated with current levels and mixtures of contaminants. Fewer still address effects specific to the juvenile life-stage of salmonids. The present study evaluated contaminant-related effects from dietary exposure to environmentally relevant concentrations and mixture profiles in juvenile Chinook salmon from industrialized waterways in the U.S. Pacific Northwest using two end points: growth assessment and disease susceptibility. The dose and chemical proportions were reconstituted based on environmental sampling and analysis using the stomach contents of juvenile Chinook salmon recently collected from contaminated, industrialized waterways. Groups of fish were fed a mixture with fixed proportions of 10 polychlorinated biphenyls (PCBs), 3 dichlorodiphenyltrichloroethanes (DDTs), and 13 polycyclic aromatic hydrocarbons (PAHs) at five concentrations for 35 days. These contaminant compounds were selected because of elevated concentrations and the widespread presence in sediments throughout industrialized waterways. Fork length and otolith microstructural growth indicators were significantly reduced in fish fed environmentally relevant concentrations of these contaminants. In addition, contaminant-exposed Chinook salmon were more susceptible to disease during controlled challenges with the pathogen Aeromonas salmonicida. Our results indicate that dietary exposure to contaminants impairs growth and immune function in juvenile Chinook salmon, thereby highlighting that current environmental exposure to chemicals of potential management concern threatens the viability of exposed salmon.

A new insight into the emission source of DDT in indoor environment from rural area of South China and comprehensive human health exposure assessment.

Human exposure to dichlorodiphenyltrichloroethanes (DDTs) and the subsequent risk to human health remain an important concern due to the "new" input of DDTs in the environment, especially since exposure to DDTs in indoor microenvironments is often ignored. In this study, we identified a new source of DDT emission in indoor environments and evaluated the health risk from the exposure to DDTs by investigating DDTs in indoor and outdoor dust, air, and coatings of household items in rural areas of Qingyuan, South China. The concentrations of DDTs in house dust and air were < MQL (method quantification limit)-3450 ng/g (median 42.4 ng/g) and 22.7-965 pg/m3 (median 49.5 pg/m3), respectively, which were significantly higher than the outdoor DDT values. Dichlorodiphenyldichloroethylene (DDE) was the main isomer in air samples, while DDT was the dominant isomer in indoor dust. Significant correlations between different DDT isomers were observed in indoor samples but not in outdoor samples. Furniture coating was identified as a source of DDTs in the indoor dust. The total daily exposure dose of DDTs (1.75 × 10-2 ng/kg bw/day for adults and 1.28 × 10-1 ng/kg bw/day for toddlers) through inhalation, dust ingestion, and dermal contact was found unlikely to pose a health risk. Our findings provide new insights into the emission sources and health risks caused by DDT indoors, highlighting the need to further investigate the toxicity mechanisms of parent DDT compound.

[Distribution and Potential Risk of Organochlorine Pesticides in the Soil of a Submerged Area Around Miyun Reservoir].

Soil samples collected from a submerged area around Miyun Reservoir were analyzed for organochlorine pesticide (OCP) residues using GC-MS. The distribution characteristics and possible sources of OCPs were studied, as well as the potential ecological risk. The results showed the following:① the residuals of OCPs in the surface soil were mainly hexachlorocyclohexanes (HCHs) and dichlorodiphenyltrichloroethanes (DDTs), and the average contents of HCHs and DDTs were 1.74 ng·g-1 and 1.01 ng·g-1, respectively. In comparison with other lakes and reservoirs in China, the mean value of DDT content of the soil samples from Miyun Reservoir was slightly less, whereas the mean value of HCH content was similar to other waterbodies. ② There was a distinct spatial distribution of OCPs in soils of the submerged area. Specifically, the OCP content in the water-land interlaced soil was generally higher, with distinct differences to the water or in land. In the eastern region of the reservoir and in the Chaohe River inflow area, the residues of OCPs were mainly DDTs, as was the case for the submerged soils of small isolated watersheds. The OCPs in the submerged area of the northern reservoir and the western central reservoir were mainly γ-HCH residues, while HCH and DDT residues were found in high proportions in the flooded area where the Baihe River inflows. These patterns were related to sources of pollutants; ③ the source analysis showed that sources of HCHs could be related to lindane input, while DDTs mainly derived from the early residues in the environment; ④ there was low ecological risk from OCPs in most of the samples, and a potential risk from DDT in the Baihe inflow area and in the central submerged zone of the western reservoir.

Response of microbial communities to different organochlorine pesticides (OCPs) contamination levels in contaminated soils.

Understanding microbial community structure and diversity in contaminated soils helps optimize the bioremediation strategies and performance. This study investigated the roles of environmental variables and contamination levels of organochlorine pesticides (OCPs) in shaping microbial community structure at an abandoned aged insecticide plant site. In total, 28 bacterial phyla were identified across soils with different physiochemical properties and OCPs levels. Proteobacteria, Bacterioidetes and Firmicutes represented the dominant lineages, and accounted for 60.2%-69.2%, 5.6%-9.7% and 6.7%-9.4% of the total population, respectively. The overall microbial diversities, in terms of phylogenetic diversity and phylotype richness, were correlated with the contents of hexachlorocyclohexanes (HCHs) and dichlorodiphenyltrichloroethanes (DDTs) in soils, as well as other soil properties including total nitrogen, dissolved organic carbon, pH and vegetation. The multivariate regression tree (MRT) analysis revealed that the soil microbial diversity was significantly impacted by vegetation, which explained 31.8% of the total variation, followed by OCPs level (28.3%), total nitrogen (12.4%), dissolved organic carbon (6.3%) and pH (2.4%). Our findings provide new insights and implications into the impacts on soil microbial community by OCPs contamination and other environmental variables, and offer potential strategic bioremediation for the management of OCPs contaminated sites.