Organochlorine pesticides in soil samples across urban, suburban, agricultural, and industrial sites were analyzed every year between 2013 and 2016 in South Korea. The study aims to understand the residual status, diminution of occurrence from the South Korean environment, and its risk to humans after three decades of the ban. A general decreasing trend of OCPs has been observed over the years. The OCP concentrations were below the guideline values prescribed for soil pollution. Metabolites like p,p’-DDD and endosulfan sulfate contributed a major portion to the total OCP concentration over the years. The agricultural sites showed higher OCP levels than other site types. Compositional profile and diagnostic ratios suggested that the occurrence of DDT and endosulfan residues were due to historical inputs, but those of HCH and chlordane reflect recent usage in some pockets. The calculated incremental lifetime cancer risk was within the safety limit for all age groups across the genders in the majority of the sites. It is evident that the OCP load on soil is decreasing since the ban on usage. However, regular monitoring with a special focus on metabolites can be an effective control measure to regulate and eliminate the contamination of OCPs.

Organochlorine pesticides (OCPs) have been reported to cause mitochondrial dysfunction. However, most studies reported its mitochondrial toxicity with respect to a single form, which is far from the environmentally relevant conditions. In this study, we exposed zebrafish embryos to five OCPs: chlordane, heptachlor, p,p’-dichlorodiphenyltrichloroethane (p,p’-DDT), β-hexachlorocyclohexane (β-HCH), and hexachlorobenzene (HCB), as well as an equal ratio mixture of these OCPs. We evaluated mitochondrial function, including oxygen consumption, the activity of mitochondrial complexes, antioxidant reactions, and expression of genes involved in mitochondrial metabolism. Oxygen consumption rate was reduced by exposure to chlordane, and β-HCH, linking to the increased activity of specific mitochondrial complex I and III, and decreased GSH level. We found that these mitochondrial dysfunctions were more significant in the exposure to the OCP mixture than the individual OCPs. On the mRNA transcription level, the individual OCPs mainly dysregulated the metabolic cycle (i.e., cs and acadm), whereas the OCP mixture disrupted the genes related to mitochondrial oxidative phosphorylation (i.e., sdha). Consequently, we demonstrate that the OCP mixture disrupts mitochondrial metabolism by a different molecular mechanism than the individual OCPs, which warrants further study to evaluate mitochondrial dysregulation by chronic exposure to the OCP mixture.

We conducted the first comprehensive assessment of the presence, source, and ecotoxicological implication of 13 banned and restricted organochlorine pesticides (OCPs) in the surface water along the Ganga River for two different seasons. Surface water samples were collected along the 2525 km stretch of the Ganga through 43 sites representing five zones of diverse land-use pattern, pesticide consumption rate, and varied flow. The mean concentrations of ΣOCPs were significantly higher (∼2–5 times) in the post-monsoon or wet season [range: 0.126 to 10.402 μg/L (mean: 2.482 μg/L ± 3.589 and median: 1.433)] than in the post-winter or dry season [range: 0.053 to 3.010 μg/L (mean: 0.765 μg/L±1.033 and median: 0.399)]. Lindane (γ-HCH) was the dominant and most frequently detected pesticide at all the sites, indicating possible continued use of this banned pesticide in agricultural practices. The spatial distribution of OCPs revealed non-significant difference amongst different zones and indicate that point source pollution from the open drains along the Ganga could be responsible for observed trend. Ratio diagnostic analysis highlighted the fresh inputs and potential illegal use of lindane and chlordane at all the zones whereas, historical use of DDT was revealed at the majority of sites. Interestingly, fresh inputs of DDT were observed in the relatively pristine high altitude Upper zone (UZ) suggesting long-range atmospheric transfer and its continued use in the zone. Risk quotient (RQ) analysis revealed high ecotoxicological risks (>1), at all the studied sites for p, p’ DDE. The lower zone (LZ) emerged as a high ecological risk zone. The study highlights that though the OCPs analysed in this study are banned/restricted in India, still the implementation of the ban is poor and delayed and the country requires stricter adherence to its National Implementation Plan (NIP) on pesticides.

Humpback whales, Megaptera novaeangliae, breeding off la Reunion Island (Indian Ocean) undergo large-scale seasonal migrations between summer feeding grounds near Antarctica and their reproductive winter grounds in the Indian Ocean. The main scope of the current study was to investigate chemical exposure of humpback whales breeding in the Indian Ocean by providing the first published data on this breeding stock concerning persistent organic pollutants (POPs), namely polychlorinated biphenyls (PCBs), hexachlorobenzene (HCB), hexachlorocyclohexanes (HCHs), DDT and its metabolites (DDTs), chlordane compounds (CHLs), polybrominated diphenyl ethers (PBDEs), and methoxylated PBDEs (MeO-PBDEs). Analyses of stable isotopes δ13C and δ15N in skin resulted in further insight in their feeding ecology, which was in agreement with a diet focused mainly on low trophic level prey species, such as krill from Antarctica. POPs were measured in all humpback whales in the order of HCB > DDTs > CHLs > HCHs > PCBs > PBDEs > MeO-BDEs. HCB (median: 24 ng g−1 lw) and DDTs (median: 7.7 ng g−1 lw) were the predominant compounds in all whale biopsies. Among DDT compounds, p,p′-DDE was the major organohalogenated pollutant, reflecting its long-term accumulation in humpback whales. Significantly lower concentrations of HCB and DDTs were found in females than in males (p < 0.001). Other compounds were similar between the two genders (p > 0.05). Differences in the HCB and DDTs suggested gender-specific transfer of some compounds to the offspring. POP concentrations were lower than previously reported results for humpback whales sampled near the Antarctic Peninsula, suggesting potential influence of their nutritional status and may indicate different exposures of the whales according to their feeding zones. Further investigations are required to assess exposure of southern humpback whales throughout their feeding zones.

The fraction of trans-chlordane (TC) in chlordane was used to indicate racemic degradation while the enantiomer fractions (EFs) indicated enantioselective depletion. In 44 soils of the Central Tibetan Plateau, the fractions of TC ranged from 0.368 to 0.411. The EFs ranged from 0.174 to 0.696 for TC and from 0.483 to 0.672 for cis-chlordane (CC). (−) enantiomer excess (ee) was found to be 80.0% in the soils for TC and (+) ee was 86.5% for CC. The fraction of TC changed with the clay content while the EFs changed with the soil organic carbon. Meanwhile, the fractions of TC and the EFs were determined for the surficial sediments in Yamzhog Yumco Lake, which were compared with those in the soils at its catchment area. The composition and chiral signature of chlordane did not vary between soils and sediments. Our results will help to elucidate the transformation of chlordane in soils and in surficial transport.

Available data were reviewed to assess the status of contamination by persistent organic pollutants (POPs), including organochlorine pesticides (OCPs), polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs), polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (PCDD/Fs), perfluorooctane sulfonate (PFOS) and perfluorooctanoate (PFOA), in drinking water sources and coastal waters of China. The levels of POPs in China's waters were generally at the high end of the global range. A comparison of China's regulatory limits indicated that PCBs in rivers and coastal water may pose potential human health risk. Occurrence of DDTs in some rivers of China may also pose health risk to humans using the regulatory limits of DDTs recommended by the European Union. Future monitoring of POPs in China's waters should be directed towards analytes of concern (e.g. PCBs and PCDD/Fs) and to fill data gaps for analytes (e.g. PBDEs, PCDD/Fs, and chlordane) and in watersheds/regions (e.g. West China) where data are scarce.

The occurrence of persistent organochlorine pesticides (OCPs) in breast milk samples collected from mothers from twelve provinces in mainland China was investigated. Dichlorodiphenyltrichloroethanes (DDTs) were the most prevalent agent, followed by HCHs and HCB, whereas levels of chlordane compounds, drins and mirex were lower. The relatively lower DDE/DDT ratio in the Fujian rural area suggested more recent exposure to DDT than in other areas. The mean level of DDTs in breast milk from the southern China was higher than those from northern China (p < 0.05). A positive correlation was observed between concentration of DDTs in human milk and consumption of animal-origin food, suggesting that this parameter could play an important part in influencing OCPs burdens in lactating women. The mean estimated daily intakes of different OCPs for breastfed infants were lower than the tolerable daily intake.

Long-term air monitoring data for POPs are required to determine the effectiveness of source reduction measures and factors controlling air concentrations. Air samples were collected between 1992 and 2012 at three sites with different geographical characteristics (Burnt Island, Egbert and Point Petre) in the Canadian Great Lakes Basin (GLB) using high-volume samplers and analyzed for organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs). Spatial and temporal trends of gas-phase concentrations of OCPs, selected PCB congeners and ƩPCBs (84 congeners) were assessed. Egbert had the highest concentrations of some OCPs due to historical [dichlorodiphenyltrichloroethanes (DDTs), dieldrin, γ-hexachlorocyclohexane (γ-HCH)] and current (endosulfan) applications of these pesticides in the surrounding agricultural cropland. This shows that agricultural areas are a source of OCPs to the GLB. High o,p'-/p,p'-DDT ratios were determined and an increasing trend was observed at Point Petre and Burnt Island up to 2004; indicating that the GLB is influenced by dicofol-type DDT sources, which have higher o,p’-/p,p’-DDT ratios than technical DDT. Atmospheric PCB concentrations at Egbert and Point Petre are higher than those measured at Burnt Island, likely due to urban influence and greater populations. Loadings calculations suggest that the atmosphere is a source of α-endosulfan and p,p’-DDT to the lakes and the opposite is true for p,p’-DDE. Long-term decreasing trends were observed for both OCPs and PCBs; consistent with control measures implemented in North America. Atmospheric PCB concentrations are decreasing relatively slowly, with halflives in the range of 9–39 years. Chlordane, α-endosulfan, β-endosulfan, dieldrin, and DDT-related substances showed halflives in the range of 7–13 years. α-HCH and γ-HCH were decreasing rapidly in air, with halflives of 5 years. Long-term declining trends of PCBs and OCPs suggest that regulatory efforts to reduce emissions to the GLB environment have been effective, but emissions from primary and secondary sources might limit future declines.

Organochlorine pesticides (OCPs) with different usage states, such as currently, historically or never used, may show different behaviors and potential risks in the environment. It is essential to identify their distribution patterns and fates and to assess their associated health risks to humans. In this study, based on a nationwide sampling campaign across China, we determined the concentrations of currently (endosulfan), historically (chlordane and heptachlor) and never-used (aldrin, dieldrin and endrin) OCPs in agricultural soils. The total residue inventories of ∑Endosulfans, ∑Chlordanes, heptachlor and ∑Drins in soils were 260, 64.3, 54.2 and 88.6 t, respectively. The residues of endosulfan were influenced by current usage, showing a latitude transect trend. Drins were mainly from long-range transport, but the illegal usage in China still affected their residues. This finding indicates that endosulfan and drins in Chinese agricultural soils mainly follow the primary and secondary distribution pattern, respectively. Both primary and secondary distribution have a great impact on the distribution pattern of chlordane, which had been banned for only 4 years at the time we sampled. The health risks of these OCPs were estimated based on their concentrations. There were 0.813% and 1.63% of samples that exceeded the target values for chlordane and endrin according to the Netherlands guideline for unpolluted soil. Their residues in most of the samples posed no or few non-carcinogenic and carcinogenic risks to human beings. The results from this study will provide powerful support for pollution control and management.