Persistent organic pollutants (POPs) in deep-sea sediments of the tropical western Pacific Ocean

Persistent organic pollutants (POPs) are toxic compounds that can persist for extended periods in the environment. The marine environment is considered an important sink for POPs. However, information regarding POPs in deep-sea environments remains limited. In this study, surface sediments from depths below 2,000 m were collected in the western Pacific Ocean to analyze polycyclic aromatic hydrocarbons (PAHs), organic pesticides, and polychlorinated biphenyls (PCBs). The concentrations of PAHs were highest (5.2-24.6 ng g^-1 dw). Hexachlorocyclohexanes (HCHs) were the predominant organic pesticide (30-1,730 pg g^-1 dw). Dicofol, chlorpyrifos, and malathion were detected only at a few sites. PCBs were not detected in the study area. A principal component analysis with multiple linear regression (PCA-MLR) indicated that PAHs in sediments mainly originated from biomass and coal combustion (∼62%) and petrogenic (∼38%) sources. This study revealed the distribution and potential sources of POPs in sediments of a deep-sea region in the western Pacific Ocean. Further studies of the transformations, sedimentation, and biological interactions of POPs are needed to better understand the fates of POPs in the marine environment and the ecological risks they pose.

Organochlorine pesticides exposure may disturb homocysteine metabolism in pregnant women

Maternal exposure to organochlorine pesticides (OCPs) has an adverse impact on maternal and fetal health, and excessive homocysteine is related to a variety of adverse pregnancy outcomes. Biomimetic studies suggest that OCPs interfere with folate-dependent pathways, but little evidence is available from studies with human subjects. This study explored whether exposure to OCPs interferes with the metabolism of homocysteine, which is folate dependent. A total of 313 pregnant women at 12-20 weeks gestation were recruited in Shanxi province, China, from 2014 to 2015. Plasma concentrations of 20 OCPs, including dichlorodiphenyltrichloroethane and metabolites (DDTs), hexachlorobenzene (HCB), and hexachlorocyclohexanes (HCHs), were analyzed by gas chromatography-mass spectrometry. Blood folate concentrations were analyzed by microbiological assay, and plasma homocysteine concentrations were determined by enzyme-linked immunosorbent assay. Information on demographics, lifestyle behaviors, and folic acid supplementation was collected by in-person interview. Of the women, 99% reported having taken folic acid supplements. Results of a logistic regression analysis showed that higher plasma levels of OCPs were associated with increased odds of higher plasma homocysteine after adjustment for potential confounding factors. Positive correlations were observed between plasma OCPs and plasma homocysteine concentrations: HCB (r = 0.176, p = 0.002), β-HCH (r = 0.172, p = 0.002), ρ,ρ'-DDE (r = 0.132, p = 0.020), ρ,ρ'-DDD (r = 0.161, p = 0.004), and ο,ρ'-DDT (r = 0.144, p = 0.011). Plasma concentrations of OCPs were negatively correlated with red blood cell (RBC) folate in the low-RBC-folate subgroup, but the correlations were not statistically significant. A positive correlation was observed between OCPs and homocysteine in the low-RBC-folate subgroup. These findings suggest that OCPs may disturb the folate-dependent homocysteine metabolism pathway.

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.

Organochlorine pesticides in follicular fluid of women undergoing assisted reproductive technologies from central China

Female infertility rates have increased by approximately 4% since the 1980s. There is evidence of adverse effects on female fertility in relation to exposure of chemical pollution in recent years. Follicular fluid samples were collected from 127 woman patients (aged 20-35) who underwent assisted reproductive technologies (ART) and had no records indicating occupational exposure to OCPs. Seventeen OCPs were analyzed in this study. The results showed that methoxychlor was dominant, accounted for 13.4% of total OCPs with a mean concentration of 167.9 ± 33.9 ng/g lipid weight (lw), followed by heptachlor-epoxide, hexachlorocyclohexanes, endrin and DDT. The concentrations of OCPs in the follicular fluid samples in the present study were moderate in comparison with those reported from developed or industrialized countries. All these pollutants can accumulate in different tissues of human body through diet, drinking water and respiration. No correlation between patient age and OCP concentrations was observed in this study.