Vertical distribution and effect of historical residual organochlorine pesticides on microbial community structure in sediment cores from an abandoned oxidation pond after dredging for 15 years

Review of scientific literature on available methods of assessing organochlorine pesticides in the environment

Organochlorine pesticides (OCPs) are persistent organic pollutants (POPs) widely used in agriculture and industry, causing serious health and ecological consequences upon exposure. This review offers a thorough overview of OCPs analysis emphasizing the necessity of ongoing work to enhance the identification and monitoring of these POPs in environmental and human samples. The benefits and drawbacks of the various OCPs analysis techniques including gas chromatography-mass spectrometry (GC-MS), gas chromatography-electron capture detector (GC-ECD), and liquid chromatography-mass spectrometry (LC-MS) are discussed. Challenges associated with validation and optimization criteria, including accuracy, precision, limit of detection (LOD), and limit of quantitation (LOQ), must be met for a method to be regarded as accurate and reliable. Suitable quality control measures, such as method blanks and procedural blanks, are emphasized. The LOD and LOQ are critical quality control measure for efficient quantification of these compounds, and researchers have explored various techniques for their calculation. Matrix interference, solubility, volatility, and partition coefficient influence OCPs occurrences and are discussed in this review. Validation experiments, as stated by European Commission in document SANTE/11813/2017, showed that the acceptance criteria for method validation of OCP analytes include ≤20 % for high precision, and 70-120 % for recovery. This may ultimately be vital for determining the human health risk effects of exposure to OCP and for formulating sensible environmental and public health regulations.

A national-scale distribution of organochlorine pesticides (OCPs) in cropland soils and major types of food crops in China: Co-occurrence and associated risks

Organochlorine pesticides (OCPs) are persistent organic pollutants (POPs) that resist degradation in the environment. OCPs remain detectable in cropland systems in China. However, spatial distribution of OCPs across China and associated ecological and health risks, as well as the relationship between levels of OCPs in cropland soils and crops, remain to be elucidated. To fill these gaps, we conducted a national-scale characterization of 19 individual OCPs in cropland soils and food crops including cereals and legumes in China, which were on-spot sampled simultaneously. Sparse canonical correlation analysis was employed to investigate the co-occurrence of OCPs in cropland soils and corresponding food crops. The ecological soil screening levels and risk quotient method were adopted for ecological and health risk assessment, respectively. Dichlorodiphenyltrichloroethanes (DDTs) were dominant in cropland systems, with its levels ranging up to 337 and 22.8 μg/kg in cropland soils and food crops, respectively. The mean ∑OCP levels in cropland soils varied from below the limit of detection to 337 μg/kg. Peanuts were the most contaminated crop, in which endosulfans and hexachlorobenzene (HCB) were co-occurrent with those in cropland soils (correlation coefficient R = 0.999 and 0.947, respectively). Besides, lindane and β-endosulfan in rice were co-occurrent with those in cropland soils (R = 0.810 and 0.868, respectively). The componential ratio analysis indicated fresh inputs of technical DDT, lindane, chlordane, endosulfan, HCB and aldrin. Among these pesticides, ecological impacts of DDTs, lindane, aldrin and β-endosulfan could be expected. Human health risk assessment suggested that daily consumption of the OCP-contaminated food crops raises a health concern especially for male teens. It is concluded that OCPs remain present in cropland systems in China at levels that raise a concern for both environment and human health.

A large geographic-scale characterization of organochlorine pesticides (OCPs) in surface sediments and multiple aquatic foods of inland freshwater aquaculture ponds in China: Co-occurrence, source and risk assessment

Inland freshwater aquaculture ponds (IFAPs) represent the key component of the global lentic freshwater environment and are increasingly important for global aquaculture production, yet the occurrence of organochlorine pesticides (OCPs) in these pond systems remains largely unknown. Here, we characterized the residual concentrations of 19 individual OCPs in sediments and in cultured fish and crustacean species (crabs, shrimp, crayfish and lobster), which were on-spot sampled from the IFAPs at a large region-scale in China. The total OCP levels in sediments varied dramatically between regions. Crabs presented the greatest OCP contamination among the studied species. Dichlorodiphenyltrichloroethanes (DDTs) was the dominating contaminant in sediments and crabs and its stable degradation products 4,4'-DDE and 4,4'-DDD were co-occurrent between these two compartments. The diagnostic ratio analysis indicated fresh inputs of DDTs, lindane and aldrin in multiple regions, which may be resulted from agricultural soil erosion, surface runoff and local anthropogenic activities. Ecological impacts of these pesticides could be expected at some sites due to their levels in sediments above the risk level. Risk assessment based on the OCP levels corrected by the cooking loss revealed that daily consumption of the IFAPs-derived aquatic foods may pose carcinogenic risks in humans.