Zooplankton taxa repository of DDTtot and sumPCB14: Seasonal and decadal variations in Lake Maggiore

Lake Maggiore has been the subject of a monitoring program on persistent organic pollutants (DDTs and PCBs) since 1996 when DDT contamination was first detected. In this context, in 2009 we started to estimate the concentration of DDTtot (Dichlorodiphenyltrichloroethane, sum of p,p'-DDT, o,p'-DDT, p,p'-DDD, o,p-DDD, p,p-DDE, o,p-DDE) and sumPCB14 (polychlorinated biphenyls 18, 28, 31, 44, 52, 101, 118, 149, 138, 153, 170, 180, 194 and 209) in zooplankton pelagic organisms preyed on by zooplanktivorous fish (size fraction ≥450 μm). We evaluated taxa specific repositories of DDTtot and sumPCB14, their seasonal variation, their changes over the period 2009-2021 and the potential contribution of different taxa in transferring toxicants to whitefish, based on the Ivlev's Electivity Index. The repository of both POPs was generally higher in spring. A decrease in the zooplankton Standing Stock Biomass (SSB) drove a decline in the zooplankton DDTtot repository over the last six years (2016-2021 SSBmean = 12.5 mg m-3; 2009-2015; SSBmean = 30 mg m-3), despite the concentration being broadly constant during this period. The sumPCB14 repository was generally characterized by lower values during the last six years, but the difference with the previous period was not so marked. Daphnia and cyclopoids were the major contributors to the repository; however, when the whitefish selectivity index was applied, the role of carnivorous Bythotrephes was more important to the detriment of cyclopoids, particularly in summer and winter. Our results are useful to elaborate predictive models on the transfer of POPs along the food chain and highlight not only the importance of freshwater zooplankton in toto, but also that different taxa can have different roles. The increasing importance of microphagous zooplankton, driven by water warming and extended thermal stratification, underlines the need for future studies on the role of small zooplankton as carriers of POPs in freshwater lakes.

Diffusion of organochlorine (OCPs) and cypermethrin pesticides from rohu (Labeo rohita) internal organs to edible tissues during ice storage: a threat to human health

The migration of organochlorine pesticides (OCPs) and cypermethrin residues from internal organs to edible tissues of ice-held Labeo rohita (rohu) was investigated in this study. The liver (246 µg/kg) had the highest level of ∑OCP residues, followed by the gills (226 µg/kg), intestine (167 µg/kg), and muscle tissue (54 µg/kg). The predominant OCPs in the liver and gut were endosulfan (53-66 µg/kg), endrin (45-53 µg/kg), and dichloro-diphenyl-trichloroethane (DDT; 26-35 µg/kg). The ∑OCP residues in muscle increased to 152 µg/kg when the entire rohu was stored in ice, but they decreased to 129 µg/kg in gill tissues. On days 5 and 9, the total OCPs in the liver increased to 317 µg/kg and 933 µg/kg, respectively. Beyond day 5 of storage, total internal organ disintegration had led to an abnormal increase in OCP residues of liver-like mass. Despite a threefold increase in overall OCP residues by day 9, accumulation of benzene hexachloride (BHC) and heptachlor was sixfold, endrin and DDT were fourfold, aldrin was threefold, and endosulfan and cypermethrin were both twofold. Endosulfan, DDT, endrin, and heptachlor were similarly lost in the gills at a rate of 40%, while aldrin and BHC were also lost at 60 and 30%, respectively. The accumulation of OCP residues in tissues has been attributed to particular types of fatty acid derivatives. The study concluded that while pesticide diffusion to edible tissues can occur during ice storage, the levels observed were well below the allowable limit for endosulfan, endrin, and DDT.

Monk seals (Monachus monachus) in the Mediterranean Sea: The threat of organochlorine contaminants and polycyclic aromatic hydrocarbons

The Mediterranean monk seal (Monachus monachus) is an emblematic species of conservation concern. Anthropogenic pressures have led to severe population declines and significant fragmentation of the remaining populations. Because of their close relationship with coastal areas, Mediterranean monk seals may be potentially exposed to pollution from agricultural sources, as well as from oil tanker spills. Although monitoring of pollution has long been considered a priority for this species, data on monk seal contamination levels are scarce. In this study, 55 blubber samples of all genders and age classes collected during necropsies (1995-2013) from seals of the Eastern Mediterranean subpopulation were analyzed for organochlorine compounds (OCs), i.e., hexachlorobenzene (HCB), polychlorinated biphenyls (PCBs) and dichlorodiphenyltrichloroethane (DDTs), and polycyclic aromatic hydrocarbons (PAHs). Overall, PCBs > DDTs ≫ PAHs > HCB in all samples. Results showed a significant downward trend over the 19-year period for DDTs and HCB. No marked pattern was found for PAHs, even though relative abundance of cancerogenic PAH fraction rose in recent years. PCB levels in subadult specimens increased noticeably over time despite worldwide ban. Our findings did not suggest recent releases of DDT or new pesticides (e.g., Dicofol) in the environment, but may indicate an improper disposal of ancient storages of PCBs or a remobilization from reservoirs. OC levels exceeded thresholds that are commonly associated with immunosuppression and reproductive impairment in other pinnipeds. Hence, OCs could be responsible of potential toxicological effects in this subpopulation. This study represents the first report on PAH and one of the few reports on OC bioaccumulation in Mediterranean monk seals. Based on the levels found in the blubber of monk seals from the Eastern Mediterranean, and given the known harmful effects associated to the prolonged exposure to these substances and the reduced long-term expectations of species recovery, regular monitoring is advocated.

Disentangling the History of Deep Ocean Disposal for DDT and Other Industrial Waste Off Southern California

Ocean disposal of industrial waste from technical DDT [mainly 1,1'-(2,2,2-trichloroethane-1,1-diyl)bis(4-chlorobenzene), or 4,4'-DDT] manufacture occurred historically in the Southern California Bight. However, the paucity of historical records highlights uncertainties as to the mode, location, and timing of disposal or ongoing ecological effects of these wastes. This study combines sampling, chemical analysis, and numerical modeling of deep San Pedro Basin sediments revealing substantial DDT contamination that extends at least 25 km from the mainland. These findings narrate bulk DDT waste disposal to the offshore that peaked in the 1950s, prior to the onset of formal regulations; was agnostic to later-designated disposal sites; and has experienced sluggish transformation. Our findings further indicate an attenuating secondary source for the DDT daughter product, 1-chloro-4-[2,2-dichloro-1-(4-chlorophenyl)ethenyl]benzene (4,4'-DDE), which still deposits into deep San Pedro Basin sediments. While demonstrating the severity of DDT contamination to the region, these findings further define the burial potential of DDT wastes and inform the past, present, and future contamination potential that is needed to understand and predict ecological consequences. This work also points firmly to bulk, not containerized, disposal of DDT waste and to potential alternative contents of collocated waste.

Apparent Khat chewers exposure to DDT in Ethiopia and its potential toxic effects: A scoping review

Dichlorodiphenyltrichloroethane (DDT) is an insecticide, a member of dirty dozen persistent organic pollutants, used widely in the world until it was banned in the 1970s.The banning of DDT was strengthened by the Stockholm Convention in 2001. DDT is allowed only for malaria control in Ethiopia. However, farmers are misusing DDT and applying it to Khat (Catha edulis) farming. So, this review analyzes available data in the literature on the current trend, application, occurrence, fate and effects of DDT and its metabolites, dichlorodiphenyldichloroethane (DDD), dichlorodiphenyldichloroethylene (DDE), in the chewable parts of Khat. Generally, the concentration level of DDT, DDD, and DDE, designated as DDTs, is detected in different farmlands of Ethiopia. Some of the DDTs concentrations detected are very high (141.2-973 μg/kg (Gelemso), 194.4-999 μg/kg (Aseno) and 6253-8413.3 μg/kg (Gurage), and these concentrations may indicate increasing recent unmonitored application of DDT on Khat leaves. Some of the detected concentrations of DDT in the literature were above the maximum residue limit (MRL) set by FAO/WHO (100 μg/kg) and the European Commission 10 μg/kg in vegetables and 50 μg/kg in cereals. DDT exposure of Khat chewers linked to the concentration of DDT on Khat leaves and the amount of Khat consumed. DDT might pose health risks to chewers due to chronic toxicity, bioaccumulation, persistent and endocrine disruption properties.

Assessment of chlorinated pesticide exposure to white-rumped vulture Gyps bengalensis in India

Populations of the critically endangered white-rumped vulture (WRV) Gyps bengalensis have declined drastically due to the use of diclofenac for veterinary purposes in Indian subcontinent. Thirty-two dead WRVs collected from three states, namely Gujarat, Assam and Tamil Nadu in India between 2011 and 2014 were investigated to understand the role of diclofenac in the death, and the results were published. Furthermore, since organochlorine pesticides have been linked to long-term impact on populations in many species of birds across the globe, available tissues of 21 WRVs were tested also for six organochlorine pesticides (DDT, HCH, endosulfan, heptachlor, dieldrin and dicofol) and chlorpyrifos. All vultures were found to have had one or more detectable levels of pesticides in their tissues except one. Similarly, all the pesticides included in the study were detected in at least one of the vultures analysed. DDT (95.2%) was the most frequently detected pesticide followed by HCH (90.5%), and DDT (73.6%) contributed the most to the total pesticide load. Total pesticide load ranged between below detection limit (BDL) and 8753.4 ng/g. High levels of total pesticide load recorded in gut contents showed recent exposure to these legacy pesticides even long after their ban. However, it is perceived that studied pesticides' exposure to birds and their presence in the environment is in decreasing trend in India. Although, varying levels of pesticides were detected, all of which were below the levels reported to be toxic, and also reported earlier in the same species in India. Recorded levels may not create a problem to vultures unlike diclofenac; nevertheless, as continued exposure to the pesticides studied may lead to sub lethal effects in birds, it is prudent to monitor these pesticides along with new generation pesticides and NSAIDs in the critically endangered white-rumped vulture in India, towards its conservation.

Selected pesticidal POPs and metabolites in the soil of five Vietnamese cities: Sources, fate, and health risk implications

Large quantities of organochlorine pesticides (OCPs) have been used in tropical regions. The fate processes and risks of these legacy contaminants in the tropics are poorly understood. Herein, we investigated the occurrence of three classes of widely used OCPs and their metabolites in surface and core soil from five cities across Vietnam with a prevalent tropical monsoon climate and a long history of OCP application. We aimed to elucidate migration potentials, degradation conditions, and transformation pathways and assess current health risks of these contaminants. Generally, the concentrations of OCPs and metabolites in the soil core were slightly lower than those in surface soil except for hexachlorocyclohexane (HCH) isomers. 2,2-bis(4-chlorophenyl)-1,1,1-trichloroethane (p,p'-DDT), 2,2-bis(4-chlorophenyl)-1,1-dichloroethylene (p,p'-DDE), the sum of dicofol and 4,4'-dichlorobenzophenone (p,p'-DBP), and 2,2-bis(4-chlorophenyl)-1,1-dichloroethane (p,p'-DDD) were the most abundant compounds in both surface and core soils. A uniform distribution of HCHs (the sum of α-, β-, γ-, and δ-HCH) at trace levels was found in almost all soils, serving as evidence of the lack of recent use of HCH pesticides. Higher concentrations of DDTs (the sum of DDT, DDD, and DDE) were observed in north-central Vietnamese soil, whereas appreciable concentrations of ENDs (the sum of α- and β-endosulfan and endosulfan sulfate) were only found in southern Vietnamese soils. Empirical diagnostic ratios indicated residuals of DDTs were mainly from technical DDT rather than dicofol, whereas aged HCHs could be explained by the mixture of lindane and technical HCH. Both historical applications and recent input explain DDTs and ENDs in Vietnamese soil. Total organic carbon performs well in preventing vertical migration of more hydrophobic DDTs and ENDs. The dominant transformation pathway of DDT in surface soil followed p,p'-DDE→2,2-bis(4-chlorophenyl)-1-chloroethylene or p,p'-DDMU→1,1-bis(4-chlorophenyl)ethylene or p,p'-DDNU→p,p'-DBP, whereas the amount of p,p'-DDMU converted from p,p'-DDD and p,p'-DDE is similar in soil core. Non-cancer risks of OCPs and metabolites in all soils and cancer risks of those chemicals in core soils were below the safety threshold, whereas a small proportion of surface soil exhibited potential cancer risk after considering the exposure pathway of vegetable intake. This study implied that organic matter in non-rainforest tropical deep soils still could hinder the leaching of hydrophobic organic contaminants as in subtropical and temperate soils. When lands with a history of OCP application are used for agricultural purposes, dietary-related risks need to be carefully assessed.

Growth of Pacific staghorn sculpin (Leptocottus armatus) is reduced at contaminated sites in the Lower Duwamish River, Washington

The Lower Duwamish River is a highly industrialized waterway flowing into the densely urbanized Puget Sound waterfront of Seattle, Washington, USA. The river has been profoundly altered from its natural state following more than a century of channelization, recurrent dredging, shoreline armoring, and pollution discharges. As part of a Natural Resource Damage Assessment addressing historical pollution at three designated Superfund sites (i.e., the assessment area), juvenile Pacific staghorn sculpin (Leptocottus armatus) were sampled throughout the lower river in order to evaluate injury from exposure to polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), dichlorodiphenyltrichloroethane (DDTs), and butyltins (BTs). Sculpin live in close association with the river sediments within and upriver of the assessment area. Fish were collected for analysis of contaminant concentrations in composited whole bodies and stomach contents, as well as individual fish health metrics including daily somatic growth rates measured from otoliths. Sediment contaminant concentrations were also measured at sites near to fishing locations. Fish growth rates varied from 0.65 to 1.05 mm/day, and were significantly lower at unremediated downriver sites compared to upriver and remediated locations. Sculpin growth rates were negatively correlated with concentrations of PCBs in fish bodies, PAHs in stomach contents, as well as PCBs, DDTs and PAHs in sediment. Mixed effects models for whole-body and stomach content contaminants showed positive correlations between growth rate and water temperature. Temperature was not a significant confounding variable for the relationship between growth rate and sediment contaminants. Overall, these results show that juvenile sculpin are harmed by contaminant exposure in the Lower Duwamish River. Furthermore, this study demonstrates the utility of using paired biological and chemical indicators of pollutant-induced injury in a resident fish to inform a complex Natural Resource Damage Assessment and associated restoration efforts.

Placental concentrations of xenoestrogenic organochlorine pesticides and polychlorinated biphenyls and assessment of their xenoestrogenicity in the PA-MAMI mother-child cohort

BACKGROUND

Organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCB), they have contributed to the exposure of women to persistent organic pollutants (POPs). These compounds can cross the placental barrier and interfere with the hormonal system of newborns.

AIM

To determine concentrations of OCPs and PCBs and their xenoestrogenic activity in placentas of women from the PA-MAMI cohort of Panama.

METHODS

Thirty-nine placenta samples from women in the Azuero peninsula (Panama) were analyzed. Five OCPs [p-p'-dichlorodiphenyldichloroethylene (p-p'-DDE), beta-hexachlorohexane (β-HCH), γ-hexachlorohexane (lindane), hexachlorobenzene (HCB) and mirex] and three PCB congeners (PCB-138, PCB-153 and PCB-180) were quantified in placenta extracts. The xenoestrogenic activity of extracts was assessed with the E-Screen bioassay to estimate the total effective xenoestrogen burden (TEXB).

RESULTS

All placental samples were positive for at least three POP residues and >70% for at least six. The frequencies of quantified OCPs ranged from 100% for p,p'-DDE and HCB to 30.8% for β-HCH. The highest median concentration was for lindane (380.0 pg/g placenta), followed by p,p'-DDE (280.0 pg/g placenta), and HCB (90.0 pg/g placenta). Exposure to p,p'-DDE was associated with greater meat consumption, suggesting that animal fat is a major source of exposure to DDT metabolites. The frequency of detected PCBs ranged between 70 and 90%; the highest median concentration was for PCB 138 (17.0 pg/g placenta), followed by PCB 153 (16.0 pg/g placenta). All placentas were positive in the estrogenicity bioassay with a median TEXB-α of 0.91 pM Eeq/g of placenta. Exposure to lindane was positively associated with the xenoestrogenicity of TEXB- α, whereas this association was negative in the case of exposure to PCB 153.

CONCLUSIONS

To our best knowledge, this study contributes the first evidence on the presence of POPs and xenoestrogenic burden in placentas from Latin-American women. Given concerns about the consequences of prenatal exposure to these compounds on children's health, preventive measures are highly recommended to eliminate or minimize the risk of OCP exposure during pregnancy.

Contamination of Soil by Obsolete Pesticide Stockpiles: A Case Study of Derince Province, Turkey

The areal distributions of the soil organochlorine pesticide (OCP) levels were investigated at adjacent and surrounding sites of the obsolete pesticide stockpile warehouse in Kocaeli, Türkiye. OCP levels in soil at neighboring sampling locations (positioned at 0.4 to 3 km from the stockpile) varied from 0.4 to 9 µg/kg and 4.2 to 2226 µg/kg (dry weight) for ΣHCHs and ΣDDXs, respectively. Levels at adjacent locations (positioned within 20 m from the stockpile) were considerably higher, varying from 74 to 39,619 µg/kg and 1592 to 30,419 µg/kg for ΣHCHs and ΣDDXs, respectively. Levels of OCPs dropped abruptly with the horizontal distance from the stockpile and had different transect profiles. The enantiomer fractions (EFs) near the stockpile range from 0.494 to 0.521, 0.454 to 0.515, and 0.483 to 0.533 for α-HCH, o,p'-DDT, and o,p'-DDD, respectively. These near-racemic EFs suggested that observed soil OCP levels were mainly influenced by recent emissions from the stockpile. A comparison of OCP compositions observed in the soil at the present study with the technical HCHs and DDTs revealed that the material in the stockpile primarily contains byproducts that were discarded during DDT and Lindane production at the adjacent plant instead of their technical mixtures.

Cross-sectional and longitudinal associations of dichlorodiphenyltrichloroethane (DDT) metabolites exposure with lung function alternation in the Chinese general adults

Exposure of dichlorodiphenyltrichloroethane (DDT) pesticide was suggested to be associated with adverse effects on the respiratory system. However, the effects of DDT exposure on lung function remain unclear. Our objectives were to investigate the potential associations of internal levels of DDT and its metabolites including dichlorodiphenyldichloroethylene (DDE) and dichlorodiphenyldichloroethane (DDD) with lung function. Serum DDT, DDE, and DDD concentrations and lung function were measured among 3968 general adults from the Wuhan-Zhuhai cohort. The cross-sectional and longitudinal associations of serum DDT and its metabolites with lung function were assessed using linear mixed models. The results showed negative dose-response relationships of serum DDT, DDE, and DDD levels with forced vital capacity (FVC) and forced expiratory volume in 1 s (FEV1). In the cross-sectional analyses, each 1-unit increase in natural log-transformed values of p,p'-DDE, o,p'-DDT, o,p'-DDE, or p,p'-DDD was significantly associated with a 25.77-, 44.84-, 51.13-, or 43.44-mL decrease in FVC, respectively. Each 1-unit increase in natural log-transformed values of o,p'-DDT, o,p'-DDE, o,p'-DDD, or p,p'-DDD was significantly associated with a 35.72-, 31.87-, 29.54-, or 36.80-mL decrease in FEV1, respectively. In the three-year longitudinal analyses, each 1-unit increase in natural log-transformed serum p,p'-DDT and p,p'-DDE was significantly associated with a 35.10 mL and 36.38 mL decrease in FVC, and a 26.32 mL and 32.37 mL decrease in FEV1, respectively. In conclusion, DDT and its metabolites exposure were associated with lung function decline in the general Chinese adult population.

Correlation Between Toxic Elements and Pesticide Residues in Medicinal Herbs Available in Pharmaceutical Market

The use of medicinal plants for self-medication of minor health conditions has become a widespread practice in contemporary society. Few consumes, however, question the contamination of these products with toxic factors resulting from the planet's increasingly polluted environment. This paper presents the levels of five toxic elements (As, Cr, Pb, Cd, and Hg) and nine organochlorine pesticides (hexachlorobenzene (HCB), lindane, heptachor, aldrin, dieldrin, endrin, p,p'DDE, p,p'DDD, and p,p'DDT) in 14 brands of regularly consumed medicinal products in Romania. The toxic elements content was determined using energy-dispersive X-ray fluorescence (EDXRF) technique, and organochlorine pesticide residues (OPCs) were quantified using gas-chromatographic method, equipped with electron capture detector (GC-ECD). The results show that in the case of Cr, Cd, and Hg, the concentrations exceeded the limit values established by World Health Organisation (WHO) for raw herbal material. The higher level of OPCs (such as p,p'DDD, p,p'DDT, aldrin, and dieldrin) was found in the samples of Hypericum perforatum-St. John's wort, Crataegus monogyna-hawthorn, and Epilobium parviflorum-hoary willowherb. The correlations between the content of toxic elements and pesticides were determined by statistical analysis. Hierarchical clustering technique was used to detect natural grouping between the toxic elements and pesticides. For herb samples, four clusters were identified, the strongest correlated cluster consisting of Pb, HCB, Cr, and Hg. A further analysis within this cluster suggested that Cr levels are statistically different from the rest of the elements.

Environmental factors influencing DDT-DDE spatial distribution in an agricultural drainage system determined by using machine learning techniques

The presence and persistence of pesticides in the environment are environmental problems of great concern due to the health implications for humans and wildlife. The persistence of DDT-DDE in a Mediterranean coastal plain where pesticides were widely used and were banned decades ago is the aim of this study. Different sources of analytical information from water and soil analysis and topography and geographical variables were combined with the purpose of analyzing which environmental factors are more likely to condition the spatial distribution of DDT-DDE in the drainage watercourses of the area. An approach combining machine learning techniques, such as Random Forest and Mutual Information (MI), for classifying DDT-DDE concentration levels based on other environmental predictive variables was applied. In addition, classification procedure was iteratively performed with different training/validation partitions in order to extract the most informative parameters denoted by the highest MI scores and larger accuracy assessment metrics. Distance to drain canals, soil electrical conductivity, and soil sand texture fraction were the most informative environmental variables for predicting DDT-DDE water concentration clusters.

Dichlorodiphenyltrichloroethane (DDT) and Dichlorodiphenyldichloroethylene (DDE) levels in air and surface sea waters along the Antarctic Peninsula

Persistent organic pollutants (POPs) are widespread worldwide, even reaching polar regions. Among POPs, dichlorodiphenyltrichloroethane (DDT) and their metabolites have been reported scarcely in the Antarctic environment. Here we report the levels of p,p'-DDT, o,p'-DDT, p,p'-DDE, and o,p'-DDE in air and water samples collected during austral summer 2009. The levels found ranged from 0.25 to 4.26 pg m-3 in the atmospheric samples while in the water samples ranged from 0.07 to 0.25 pg L-1. These concentrations were within the range of the reported concentrations in the last 20 years in Antarctica. However, the source ratio showed that most of p,p'-DDT comes from fresh applications and Dicofol formulations. The back-trajectories estimated for the air masses revealed that most of the p,p'-DDT came from the continental Antarctic peninsula and surrounding waters. The diffusive exchange direction showed that Antarctic surface waters are the final sink of the studied compounds during the survey period.

Water quality, human health risk, and pesticides accumulation in African catfish and Nile tilapia from the Kitchener Drain-Egypt

Pesticides are toxic and could negatively impact humans and the ecosystem. The Kitchener Drain is among the longest drains in Egypt and carries a wide range of wastewater from the agriculture sector, which contains pesticides and may pollute the ecosystem. Thus, water quality, human health risk, and pesticide accumulation in African catfish and Nile tilapia from the Kitchener Drain-Egypt. The water and fish samples were collected from Kitchener Drain in Kafr Elsheikh Governorate, Egypt, during the four seasons. The results indicated that heptachlor and diazinon were undetected during the four seasons. However, endosulfan, chlorpyrifos, and dicofol were detected in winter and autumn. Only p,p'-DDT was detected during spring. Endosulfan, heptachlor, and aldrin were detected in Nile tilapia during winter. Only heptachlor and aldrin were detected during spring. Endosulfan, heptachlor, dicofol, p,p'-DDT, chlorpyrifos, and diazinon were detected in the autumn season. In summer, dicofol and p,p'-DDT were detected, while endosulfan, heptachlor p,p'-DDT, aldrin, chlorpyrifos, and diazinon were not detected. In African catfish, endosulfan, heptachlor, dicofol, and p,p'-DDT were detected during winter, while chlorpyrifos, aldrin, and chlorpyrifos, aldrin, and diazinon were not detected. In the spring season, endosulfan, heptachlor, and aldrin were detected. Endosulfan, heptachlor, dicofol, p,p'-DDT, aldrin, chlorpyrifos, and diazinon were detected in the autumn season. Similarly, in the summer season, endosulfan, heptachlor, dicofol, p,p'-DDT, aldrin, chlorpyrifos, and diazinon were detected. The sequence of estimated daily intake (EDI) in Nile tilapia during the four seasons is heptachlor > endosulfan > dicofol > p,p'-DDT > aldrin > diazinon > chlorpyrifos. The sequence of EDI in African catfish during the four seasons is endosulfan > p,p'-DDT > heptachlor > aldrin > dicofol > diazinon > chlorpyrifos. In conclusion, the results confirmed the absence of a hazard index for consuming Nile tilapia and African catfish collected from the Kitchener drain.

Pesticides in sediments from Magdalena River, Colombia, are linked to reproductive toxicity on Caenorhabditis elegans

Pesticides are prevalent pollutants found in river sediments in agricultural regions worldwide, leading to environmental pollution and toxic effects on biota. In this study, twenty sediment samples were collected from the Magdalena River in Colombia and analyzed for forty pesticides. Methanolic extracts of the sediments were used to expose Caenorhabditis elegans for 24 h, evaluating the effects on its reproduction. The most abundant pesticides found in Magdalena River sediments were atrazine, bromacil, DDE, and chlorpyrifos. The concentrations of DDE and the sum of DDD, DDE, and DDT were above the Threshold Effect Concentration (TEC) values for freshwater sediments, indicating potential effects on aquatic organisms. The ratios of DDT/(DDE + DDD) and DDD/DDE suggest historical contributions of DDT and degradation under aerobic conditions. Several sampling sites displayed a moderate toxicity risk to biota, as calculated by the sediment quality guideline quotient (SQGQ). Nematode brood size was reduced by up to 37% after sediment extract exposure. The presence of chlordane, DDT-related compounds, and chlorpyrifos in Magdalena River sediments was associated with reproductive toxicity among C. elegans.

Peroxymonosulfate assisted mechanochemical remediation of high concentration DDTs contaminated soil

DDTs (DDT and its metabolites) contaminated sites urgently need to be treated efficiently and greenly. In this study, a horizontal planetary mechanochemical method with co-milling additives was developed aiming at efficiently degrading high-concentration DDTs in historical contaminated soil (∼7500 mg/kg). Peroxymonosulfate (PMS) was firstly used to the mechanochemical degradation of DDTs in historical contaminated soil, with a degradation efficiency of over 95% after 1 h of milling under the optimal milling conditions (CR = 30:1, r = 500 rpm, R = 1:4). Mechanism study indicated that DDTs in soil were partially dechlorinated and mineralized. The main products formed might be chlorinated aliphatic hydrocarbons, which need further treatment by ball milling or other methods. Under the action of mechanical energy, PMS could oxidize DDTs in soil through non-radical way rather than common radical way. Then, a comprehensive assessment of this remediation method was conducted by analyzing the changes in soil properties and acute biotoxicity after ball milling. Although PMS had a great performance on the degradation of DDTs, especially p, p'-DDE, it would cause the acidification and salinization of soil. Therefore, further pH adjustment and desalination treatment were suggested to reduce the negative impacts. This work successfully presents a practical approach to mechanochemical remediation of DDTs contaminated sites.

Organochlorine contaminants in sediments and factors influencing their distribution in the natural marine protected area in the gulf of Mexico

The aim of this study was to determine the concentration of polychlorinated biphenyls (PCBs) and organochlorine pesticides (OCPs) in marine sediments of a natural marine protected area (NMPA), Veracruz Reef System (VRS), in the Gulf of Mexico (GoM). This NMPA represents one of the first coastal sites with port activity in Mexico, which causes a range of human activities that require adequate planning so as not to impact and destroy this marine protected area; In this sense, this work represents the first effort aimed at diagnosing the presence of organochlorine contaminants in reef sediments from the mainland, both from the adjacent port area and from more distant regions with dominant agricultural activities that ultimately affect this NMPA. Content of organic matter (OM), carbonates and grain-size composition were determined to investigate their influence on compounds distribution in the sediment through multivariate analysis. The potential risk represented by organochlorines concentrations was evaluated taking as reference Sediment Quality Guidelines (SQGs). Levels of ∑PCBs, ∑DDTs, ∑HCHs and ∑Cyclodienes ranged from 11.59 to 29.79, < 0.01 to 34.11, 22.10 to 102.80, and 17.21-104.45 ng g-1 dry weight (DW), respectively. The statistical analysis revealed that the content of mud and organic matter were the parameters that might influence PCBs distribution in the sediment while OCPs could be influenced by sand and carbonate. The theoretical risk assessment estimated with the results obtained showed that concentrations of lindane, endrin, dieldrin and p,p'-DDT could have an adverse effect on the reef benthic community and continued monitoring is required. The data obtained on the organochlorine contaminants (OCs) considered in this work will contribute to support the strategies proposed by the Mexican federal government entity to continue with the conservation and surveillance of this NMPA and thereby guarantee the least impact derived mainly from port and related agricultural activities.

Organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs) in adipose tissue of women from Grand Tunis and their association with demographic factors and dietary habits

Dichlorodiphenyl trichloroethane and its metabolites (DDTs), hexachlorocyclohexane isomers (HCHs), hexachlorobenzene (HCB) and polychloronated biphenyls (PCBs) were measured in 25 woman adipose tissues collected in 2016 from Grand Tunis, Tunisia. p,p'-DDE, p,p'-DDT, HCB and β-HCH were the dominant organochlorine pesticides (OCPs) in decreasing order in all samples. The total OCP levels varied from 79 to 343 ng g-1 lipid with a median value of 189 ng g-1 lipid and DDTs contributed approximately 88% to sum OCP. The ratio of p,p'-DDT/p,p'-DDE across all samples is below one, which suggests mainly historic exposure but may indicate some recent exposure to the banned pesticide. The median concentration of PCBs was 109 ng g-1 lipid and ranged between 27 and 204 ng g-1 lipid. PCB-153, PCB-180, PCB-138 and PCB-170 were the most abundant congeners, which contributed about 78% of the total PCBs. Spearman analysis showed that dominant organochlorine compounds (OCs) are highly positive correlated except for PCB-28/31, indicating that women from Tunis are exposed via similar routes. Inhalation exposure could be a possible pathway for the uptake of the less chlorinated congeners. We found positive and statistically significant association with subjects age for HCB (r = 0.517; p = 0.009) and PCBs (r = 0.65; p = 0.001) levels and a weak age-dependent accumulation was found for HCHs (r = 0.375; p = 0.065) and DDTs (r = 0.388; p = 0.056). The concentrations of OC subgroups were not associated with BMI, parity and residence. No association was observed between fish, red/white meat, milk and dairy products consumption and levels of HCB, HCHs and PCBs. DDTs levels were significantly correlated only with milk (p = 0.048) and milk products (p = 0.047) intake.

Bioaccumulation of pesticide residue in earthworms collected from the agricultural soils of Kuttanad-a unique agroecosystem in India

Earthworms encompass significant soil faunal biomass and have tremendous potential to provide vital ecosystem services. Earthworms are considered bioindicators of chemical contaminants and can provide early warnings of ecosystem deterioration. Studies pertaining to the accumulation of pesticide residues in earthworm in biomass in agrarian ecosystems are scarce. The Kuttanad agroecosystem (KAE), situated on the southwest coast of India, is one of the few regions globally supporting farming on land below the mean sea level. This investigation was conducted to assess the bioaccumulation of pesticide residues in earthworms from the KAE. The earthworms species Glyphidrilus annandalei collected from agricultural soils of the study area were analyzed for the presence of pesticides residues such as α-BHC, γ-BHC, atrazine, heptachlor, α-chlordane, γ-chlordane, 4,4-DDE, 4,4-DDD, 4,4-DDT, β-endosulfan, and endrin ketone in their biomass. Analysis of the earthworm samples using a gas chromatograph revealed the presence of ten pesticide residues with notable concentrations (α-BHC, 0.36 ng/g; γ-BHC, 0.41 ng/g; heptachlor, 0.10 ng/g; atrazine, 0.89 ng/g; α-chlordane, 0.07 ng/g; γ-chlordane, 0.10 ng/g; 4,4-DDE, 0.05 ng/g; 4,4-DDD, 0.11 ng/g; 4,4-DDT, 0.31 ng/g; β-endosulfan, 0.19 ng/g; and endrin ketone, 0.13 ng/g). Six groups of pesticide residues are ΣBHC, ΣDDT, atrazine, Σchlordane, endrin ketone, and β-endosulfan were observed during bioaccumulation factor analysis, and the results show the following trend: atrazine > ΣBHC > ΣDDT > Σchlordane > Σendosulfan > Σendrin. As earthworms are a crucial component of this region's food chains, bioaccumulation of pesticide residues in earthworms can pause adverse consequences. Increasing trends in pesticide application in the KAE and bioaccumulation of pesticide residues in earthworm biomass can affect the entire food web.

Dissent in the sediment? Lake sediments as archives of short- and long-range impact of anthropogenic activities in northeastern Germany

The suitability of lake sediment cores to reconstruct past inputs, regional pollution, and usage patterns of pesticides has been shown previously. Until now, no such data exist for lakes in eastern Germany. Therefore, 10 sediment cores (length 1 m) of 10 lakes in eastern Germany, the territory of the former German Democratic Republic (GDR), were collected and cut into 5-10-mm layers. In each layer, concentrations of trace elements (TEs) As, Cd, Cr, Cu, Ni, Pb, S, and Zn, as well as of organochlorine pesticides (OCPs), i.e., dichlorodiphenyltrichloroethane (DDT) and hexachlorocyclohexane (HCH), were analyzed. A miniaturized solid-liquid extraction technique in conjunction with headspace solid-phase microextraction (HS-SPME) and gas chromatography-mass spectrometry (GC-MS) was used for the latter. The progression of TE concentrations over time is uniform. It follows a trans-regional pattern and is indicative of activity and policy making in West Germany before 1990 instead of those in the GDR. Of OCPs, only transformation products of DDT were found. Congener ratios indicate a mainly aerial input. In the lakes' profiles, several regional features and responses to national policies and measures are visible. Dichlorodiphenyldichloroethane (DDD) concentrations reflect the history of DDT use in the GDR. Lake sediments proved to be suitable to archive short- and long-range impacts of anthropogenic activity. Our data can be used to complement and validate other forms of environmental pollution long-term monitoring and to check for the efficiency of pollution countermeasures in the past.

Pesticides in the hydrogeo-environment: a review of contaminant prevalence, source and mobilisation in India

Chemical pesticides in the hydrogeological system are a global concern as they pose a severe threat to humans and other organisms. In agriculture, around 4.12 million tonnes of pesticides were used globally in 2018, which is 50% more than in the 1990s. Various pesticides detected in the hydrogeological system of India since the 1990s have been documented and reviewed to understand the prevalence, source, history and degradation pathways. This review contributes to a better understanding of existing pesticide pollution and the state of hydrogeological resource deterioration. Small to excess levels of pesticide residues were detected in groundwater, surface water, soil, and sediments. Pesticides that were most commonly and predominantly found in the hydrogeological system were HCHs, DDTs, endosulfan, heptachlor, drins (aldrin, dieldrin, endrin), chlordane etc. β and γ-HCH isomers among HCHs, whereas p,p'-DDT and p,p'-DDE among the DDTs were detected most prevalently. In many regions, pesticide residue levels in water have exceeded the maximum residue limits of WHO and BIS, while those in soils and sediments have exceeded the threshold effect level and probable effect level. Higher pesticide residues were detected in the water resources of rural agricultural areas compared to peri-urban or urban areas. A positive correlation of pesticide residues between water resources and soil has been observed in some regions, suggesting a similar contamination source. Diagnostic ratios of pesticides reveal their source, history and degradation pathways. Diagnostic ratios observed in various studies conducted in India suggest historical as well as recent use of banned pesticides. Strengthening current policies and regulations, monitoring pesticide use, changes in pesticide application practices, awareness among farmers, and the use of prominent removal techniques are necessary to tackle pesticide contamination in India.

Review of DDT, DDE, DDD, DDMU and DDMS Toxicity Data for Organisms Used in Estuarine and Marine Sediment Toxicity Tests

The open literature was searched for laboratory toxicity data for marine/estuarine organisms exposed to dichlorodiphenyltrichloroethane (DDT) and its degradation products of dichlorodiphenyldichloroethylene (DDE), dichlorodiphenyldichloroethane (DDD), dichlorodiphenylchloroethylene (DDMU), and dichlorodiphenylchloroethane (DDMS). The goal of the review was to determine water-column toxicity values that could be used for porewater-based assessment of sediment toxicity. Data for individual compounds (and isomers thereof) in this group were very limited; most available data were for mixtures of multiple compounds, some defined and others undefined. Further, the majority of relevant studies involved exposure to spiked or field-contaminated sediment (rather than waterborne exposure), which requires inferring concentration in porewater from bulk sediment. Comparing data on the basis of effect concentrations for water or inferred concentration in sediment pore water, the lower reported effect concentrations were in the range of 0.05 to 0.1 µg/L, generally in studies of longer duration and/or evaluating sub-lethal effects. Because field exposures are generally to mixtures of these compounds in varied proportions, additional data on chemical-specific toxicity would aid in pore-water based toxicity assessment for marine/estuarine sediments contaminated with DDT-related chemicals.

Comparison of in vitro strategies for predicting Dichlorodiphenyltrichloroethane (DDT) and its metabolites bioavailability from soils

In vitro strategies have widely been used to assess bioaccessibility of organic pollutants in soils. However, studies for comparing in vitro models with in vivo data are still limited. In this study, Dichlorodiphenyltrichloroethane (DDT) and its metabolites (called as DDTr) bioaccessibility in nine contaminated soils were measured using physiologically based extraction test (PBET), in vitro digestion model (IVD), and Deutsches Institut für Normung (DIN) with/without Tenax as an absorptive sink, and DDTr bioavailability was assessed using an in vivo mouse model. Whether or not Tenax was added, DDTr bioaccessibility significantly varied among three methods, suggesting that DDTr bioaccessibility depended on the in vitro method employed. Multiple linear regression analysis indicated that sink, intestinal incubation time and bile content are identified to be the dominant factors in controlling DDTr bioaccessibility. Comparison of in vitro and in vivo results demonstrated that DIN assay with Tenax (TI-DIN) provided the best prediction for DDTr bioavailability (r² = 0.66, slope=0.78). After extending intestinal incubation time to 6 h or increasing bile content to 4.5 g/L (same to DIN assay) of the TI-PBET and TI-IVD assays, the in vivo-in vitro correlation will improved significantly, with r² = 0.76 and slope= 1.4 for TI-PBET and r² = 0.84 and slope= 1.9 for TI-IVD under 6 h intestinal incubation, and r² = 0.59 and slope= 0.96 for TI-PBET and r² = 0.51 and slope= 1.0 for TI-IVD under 4.5 g/L of bile content. The results suggest that it is essential to understand these key factors influencing bioaccessibility for the development of standardized in vitro methods, which helps to refine the risk assessment of human exposure to contaminants via soil ingestion.

Persistent organic pollutants in air from Asia, Africa, Latin America, and the Pacific

In support of the United Nations Environment Programme (UNEP) global monitoring plan under the Stockholm Convention concentrations of persistent organic pollutants (POPs) were determined during two years in air from 42 countries in Asia, Africa, Latin America, and the Pacific by using polyurethane foams installed in passive samplers. The compounds included were polychlorinated biphenyls (PCBs), organochlorine pesticides (OCPs), polybrominated diphenylethers (PBDEs), one polybrominated biphenyl and hexabromocyclododecane (HBCD) diastereomers. Total-DDT and PCBs were the highest in concentrations in about 50% of the samples, which shows their high persistency. Total DDT in air from the Solomon Islands ranged from 200 to 600 ng/polyurethane foam disk (PUF). However, at most locations, a decreasing trend is observed for PCBs, DDT and most other OCPs. Patterns varied per country with e.g. elevated dieldrin in air from Barbados and chlordane in air from the Philippines. A number of OCPs, such as heptachlor and its epoxides, some other chlordanes, mirex and toxaphene have decreased down to almost undetectable levels. PBB153 was hardly found and penta and octa--mix related PBDEs were also relatively low at most locations. HBCD and the decabromodiphenylether were more prominent at many locations and may even still increase. To draw more holistic conclusions more colder climate countries should be included in this program.

Target and non-target analysis of organochlorine pesticides and their transformation products in an agrochemical-contaminated area

Organochlorine pesticides show biological toxicity and their degradation typically takes many years. Previous studies of agrochemical-contaminated areas have mainly focused on limited target compounds, and emerging pollutants in soil have been overlooked. In this study, we collected soil samples from an abandoned agrochemical-contaminated area. Target analysis and non-target suspect screening by gas chromatography coupled with time-of-flight mass spectrometry were combined for qualitative and quantitative analysis of organochlorine pollutants. Target analysis showed that dichlorodiphenyltrichloroethane (DDT), dichlorodiphenyldichloroethylene (DDE), and dichlorodiphenyldichloroethane (DDD) were the main pollutants. With concentrations between 3.96 × 10⁶ and 1.38 × 10⁷ ng/g, these compounds posed significant health risks at the contaminated site. Non-target suspect screening identified 126 organochlorine compounds, most of which were chlorinated hydrocarbons and 90% of the compounds contained a benzene ring structure. The possible transformation pathways of DDT were inferred from proven pathways and the compounds identified by non-target suspect screening that had similar structures to DDT. This study will be useful for studies of the degradation mechanism of DDT. Semi-quantitative and hierarchical cluster analysis of compounds in soil showed that the distribution of contaminants in soil was influenced by the types of pollution sources and distance to them. Twenty-two contaminants were found in the soil at relatively high concentrations. The toxicities of 17 of these compounds are currently not known. These results improve our understanding of the environmental behavior of organochlorine contaminants in soil and are useful for further risk assessments of agrochemical-contaminated areas.

Do good carefully: The long-term effects of low-dose DDT exposure in early childhood on education, marriage and employment

It is well known that malaria has serious adverse effects on humans. Yet, little is known as to how dichlorodiphenyltrichloroethane (DDT), which is still used to control malaria, may affect human socioeconomic outcomes in the long run. Utilizing the large-scale indoor residual spraying of low-dose DDT in Taiwan in the 1950s, we estimated the long-term effects of low-dose DDT exposure in early childhood on education, marriage and employment in adulthood. Our identification hinges on the unexpected extension of DDT spraying after malaria had already been largely brought under control. We found that even at a very low dosage, DDT exposure still resulted in discernible negative effects on education and marriage. For employment, although no effect on the probability of working was detected, people exposed to more sprayings in childhood were more likely to work in the agricultural sector that typically requires less human capital.

Organochlorine pesticides induce thyroid tumors through oxidative stress; an in vivo and in silico study

Thyroid disease is one of the most common endocrine problems around the world. Among the numerous factors, exposure to environmental elements such as pesticides is associated with an increase in the incidence of thyroid disorders. The aim of the present study was to investigate the role of organochlorine pesticides (OCPs) in induction of oxidative stress (OS) and development of thyroid tumors. This case-control study was conducted on 61 patients with papillary thyroid carcinoma (PTC), 70 patients with benign thyroid nodules (BTN), and 73 healthy individuals as control. Seven derived OCPs residues measured by gas chromatography (GC), and enzyme activities of acetylcholinesterase (AChE), superoxide dismutase3 (SOD3), catalase (CAT), glutathione peroxidase3 (GPx3) and paraoxonase1 (PON1) and also, non-enzymatic antioxidant including; malondialdehyde (MDA), total antioxidant capacity (TAC), protein carbonyl (PC), and nitric oxide (NO) biomarkers in all participants were investigated. Furthermore, all of the above enzymes were docked against measured OCPs. The results revealed that β-HCH, γ-HCH, 2,4 DDE, 4,4 DDE, 2,4-DDT, and 4,4-DDT levels along with MDA, NO, and PC levels were elevated, while AChE, SOD3, GPx3, CAT, and PON1 activities and TAC levels were decreased in the PTC and BTN groups compared with the control group. Therefore, OCPs might play a role in the development of thyroid tumors through several mechanisms including generation of OS. Importantly, in silico analysis confirmed the in vivo findings.

Spatial-temporal occurrence and sources of organochlorine pesticides in the sediments of the largest deep lake (Lake Fuxian) in China

Compared with shallow lakes, less attention has been paid on pollutions in deep lakes. Lake Fuxian is the largest deep lake and an important water resource in China. The knowledge on organochlorine pesticides (OCPs) in sediments of Lake Fuxian was rare. Fifteen surface sediments and one sediment core were collected from Lake Fuxian. Sediment chronology was dated with the activities of ¹³⁷Cs and ²¹⁰Pb. Twenty-one OCPs in the surface sediments and sediment core were analyzed by a GC-MS. Spatial and temporal occurrences of OCPs in the sediments of this lake were studied. Correlations, isomer ratios, and principal component analysis (PCA) were applied to apportion the sources of OCPs in the sediments of this lake. The OCPs in the sediments of Lake Fuxian were dominated by p,p'-DDT (4,4'-dichlorodiphenyltrichloroethane) and HCHs (hexachlorocyclohexane). The concentration of ΣOCPs in the surface sediments ranged from 0.42 to 67.5 ng g^-1, with an average of 42.3 ± 23.5 ng g^-1 (mean ± SD, n = 15). The concentration of ΣOCPs in the sediment core varied from 3.5 to 707.9 ng g^-1 in the period from 1950 to 2010, with an average of 167.7 ± 203.7 ng g^-1 (n = 24). The highest concentrations and fluxes of α-HCH, γ-HCH, and p,p'-DDT were found in the years of 1964 and 1967, respectively. The fluxes of HCH isomers in the sediment core decreased in the orders as γ-HCH > β-HCH > α-HCH in the period from 1950 to 2010. The concentrations of HCHs and p,p'-DDT in the sediments of Lake Fuxian were higher than those of most shallow and deep lakes in the world. HCHs and p,p'-DDT were derived from both the technical HCH and DDT and the usage of lindane and dicofol. Technical DDT and technical HCH may be used simultaneously, but technical DDT and lindane were not applied simultaneously in the catchment. Lindane was used not only in the period from 2002 to 2010 but also in the period from 1950 to 1964 in the catchment.

Outdoor Atmospheric Micro-/Nanomineral-Mediated Organochlorine Pesticides in Sichuan Basin, China: Adsorption, Occurrence, and Risk Assessment

Atmospheric micro-/nanominerals play an important role in the adsorption, enrichment, and migration of organochlorine pesticides (OCPs). In the present study, the correlations between OCPs and minerals in outdoor atmospheric dustfall were investigated, and the correlations were used to speculate the source of p,p'-(dicofol+dichlorobenzophenone [DBP]), which is the sum of p,p'-dicofol and p,p'-DBP. Atmospheric dustfall samples were collected from 53 sites in the Chengdu-Deyang-Mianyang economic region in the Sichuan basin. In this region, 24 OCPs were analyzed by gas chromatography-tandem mass spectrometry. The average concentration of 24 OCPs was 51.2 ± 27.4 ng/g. The results showed that the concentration of Σ₂₄ OCPs in urban areas was higher than that in suburban areas (p < 0.05). Minerals in atmospheric dustfall were semiquantitatively analyzed by X-ray diffraction. The primary minerals were quartz, calcite, and gypsum. A Spearman correlation analysis of OCPs and minerals showed that low-volatility OCPs could be adsorbed by minerals in atmospheric dustfall. A density functional theory simulation verified that p,p'-(dicofol+DBP) in atmospheric dustfall was primarily derived from the p,p'-dicofol adsorbed by gypsum. Isomeric ratio results suggested that the samples had weathered lindane and chlordane profiles and confirmed that residents in the Sichuan basin used technical dichlorodiphenyltrichloroethane. Finally, the OCPs were evaluated to determine the potential risk of cancer in adults and children from OCP exposure. Exposure to OCPs via atmospheric dustfall was safe for adults. The cancer risk for children exposed to OCPs was slightly lower than the threshold value (10^-6 ) under a high dust ingestion rate, which poses a concern. Environ Toxicol Chem 2023;42:594-604. © 2022 SETAC.

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.

Organochlorines in the riverine ecosystem of Punjab province, Pakistan: contamination status, seasonal variation, source apportionment, and ecological risk assessment

The aim of the present study was to determine the occurrence, spatio-temporal variations, source apportioning, and ecological risk assessment of selected PCBs and OCPs in surface water and sediments collected riverine environment of Punjab province, Pakistan. The concentration of ΣOCPs (water: 64-455 ng/L; sediments: 117-616 ng/g) and ΣPCBs (water: 2-132 ng/L; sediments: 3.27-200 ng/g) was found comparatively higher than the levels reported from other parts of the world. The higher concentrations of DDTs and HCHs were detected in both studied matrices, whereas among PCBs, CB-28, 49 and CB-37, 82 were dominant in water and sediments, respectively. The isomeric ratios including α-HCH/γ-HCH, (DDE + DDD) / DDTs, and α /β-endosulfan reflected the recent use of lindane, technical DDT, and endosulfan in the study area. The WHO-TEQ values of DL-PCBs ranged from 3.6 × 10^-6 to 0.115 ng/L and 8.7 × 10^-6 to 0.157 ng/g in surface water and sediments in both seasons, respectively. The spatial variation analysis revealed that the sites in the industrial and agricultural zones were highly contaminated. The OCPs and PCBs fluxes to downstream areas were estimated to be 12.4 tons/year and 1.9 tons/year, respectively. The significant ecological risks were estimated to be posed by OCPs and PCBs, as their levels in 67% and 62% of surface water and sediment samples were exceeding the threshold limits, highlighting effects to ecological integrities.

Good News: Some Insecticides Have Been Virtually Eliminated in Air near the Great Lakes

Persistent insecticides have been classic environmental problems for 60-70 years─perhaps starting with Rachel Carson's indictment of DDT. Both national and international regulations have been put in place over the last 20-30 years to eventually eliminate these compounds from the environment. One focus is the atmosphere, which acts as a major long-range transport route of these pollutants from their numerous sources to many ecosystems. This paper will ask, "Have we have made any progress in eliminating insecticides from the atmosphere?" We will focus only on the atmosphere around the North American Great Lakes and only on concentration measurements made once every 12 days since about 1990 for six classic insecticides. The answer is that some of these compounds (lindane, α-HCH, and endosulfans) are well on their way to being virtually eliminated, while the concentrations of others (DDT, chlordane, and hexachlorobenzene) have not changed much. We speculate that this difference in elimination is a result of soil compaction in cities (DDT, etc.) versus soil mixing in rural areas (lindane, etc.).

A global review of the temporal and spatial patterns of DDT and dieldrin monitoring in raptors

Concentrations of organochlorine pesticides have been extensively monitored in birds, particularly from higher trophic guilds such as raptors. While monitoring of raptors has been ongoing for decades, patterns from monitoring activities have never been summarised on a global scale. In this study, we undertake a review to better describe the monitoring of two widespread organochlorine pesticides monitored globally in raptors, DDT and dieldrin. We provide a historical retrospective on the monitoring effort of a global environmental issue. Sampling was heavily biased geographically to the global north, with more than 90 % of studies conducted in this socio-geographic region, most from Europe and North America. Although monitoring occurred from at least 114 species, most samples came from relatively few species, with three species (Eurasian Sparrowhawk Accipiter nisus, Bald Eagle Haliaeetus leucocephalus, and Peregrine Falcon Falco peregrinus) comprising 50 % of samples. The types of raptors sampled have changed over time, with avian and mammal specialists dominating samples until the 1970s, but more diverse dietary guilds monitored in later decades, and greater proportions of samples coming from generalist species. The three most sampled tissues (egg, liver, and plasma) comprised 84 % of all samples. Eggs were the earliest tissue examined and the only tissue sampled in all decades. The geographical bias in monitoring effort and relatively narrow species focus, suggests that patterns in these pesticides are unlikely to be fully representative of all global environments occupied by raptors. While DDT has been banned throughout most of the global north, it remains in use in the global south, yet monitoring effort in the south, does not match that of the north. While monitoring remains prevalent in the global north, contemporary monitoring is limited in the global south with less than 10 % of raptors sampled in Asia, Africa, and South America, over the last 3 decades.

Coming ecological risks of organochlorine pesticides and novel brominated flame retardants in the Yellow River Basin

To conduct ecological risk assessment, food, water and soil samples were collected from five densely populated irrigation areas in the Yellow River Basin (YRB), and analyzed for organochlorine pesticides (OCPs) and novel brominated flame retardants (NBFRs). The results showed that the OCP residues (∑₁₄OCP were 0.748 ng L^-1, 13.1 ng g^-1 dw and 3.22 ng g^-1 dw in water, soil and maize) were generally within moderate levels in the YRB. Dichlorodiphenyltrichloroethane (DDT) residues dominated the OCPs, and potential ecological risks to aquatic and terrestrial organisms likely stemmed from dichlorodiphenyldichloroethylene (DDE) pollution in the upper reaches of the YRB in the Ningxia and Hetao Plain. The NBFR concentrations in the YRB were 90.9 pg L^-1 in water, 21.1 pg g^-1 dw in soil and 3.81 pg g^-1 dw in maize. Positive correlations were observed between soil and maize contamination in the five irrigated districts, indicating a potential threat to grain security and human health risks caused by OCPs and NBFRs. Pollutants detected in soil and maize primarily originated from historical use (36.3 %), while the sources in water were more complex (64.4 %) and new inputs could not be excluded. Integrated health risks of human exposure to agricultural products and water from the YRB were acceptable. However, the ecological risk of the Ningxia Plain would further deteriorate to the medium risk after 2032. The increasing ecological risk of DDT in water indicates that regular monitoring should strengthen to ensure grain and water safety in the YRB.

Seasonal and plurennial changes of POPs repository in freshwater zooplankton: A 10-year study in the large deep subalpine Lake Maggiore (Italy)

Determining the concentration of POPs (Persistent Organic Pollutants) such as total dichlorodiphenyltrichloroethane (DDT_tot) and polychlorinated biphenyls (PCBs) in the zooplankton is essential for evaluating the level of toxicity in the environment and the risk to ecosystem health. The extent to which POPs persist in the environment and affect human health depends on accumulation in the different components of the zooplankton community such as particle feeders and/or predators and their subsequent consumption by fish, which varies seasonally. We analyzed ten-years (2011-2020) of seasonal data on POPs in the crustacean zooplankton community of Lake Maggiore (Italy). The concentration of total DDTs, as sum of all congeners ranged between 23.5 and 156.9 ng/g dry weight, while sumPCB₁₄ ranged from 24.4 and 133.6 ng/g dry weight. We traced particle feeders' vs predatory taxa within the zooplankton community using carbon and nitrogen stable isotopic values. POPs concentration was significantly related to the nitrogen isotopic values. The zooplankton biomass increase in Spring was important, both through this being a period of increased metabolism and activity of planktivorous fish and also as it was the period when the zooplankton repository of POPs was at a maximum. DDT_tot stocked in zooplankton ≥450 μm was up to 275 ng/m², while sumPCB₁₄ was 285 ng/m² in 2013. A decrease of DDT_tot stocked in the zooplankton repository characterized the last five years examined, when mean annual values (14.8-56.9 ng/m²) were less than half those of the previous period (50.7-128.6 ng/m²).

Organochlorine pesticide contamination in sediments from Richards Bay, South Africa: spatial trends and ecotoxicological risks

The occurrence and distribution of organochlorine pesticides (OCPs) in aquatic systems is a matter of global concern and poses significant toxicological threats to both organisms and human health. Despite the extensive use of OCPs for pest and disease control in southern Africa, relatively few studies have examined the occurrence and toxicological risks of OCP residues in the region. This study investigates the composition, distribution, and potential sources of OCP contamination in sediments from Richards Bay, a rapidly developing industrial port on the northeast coast of South Africa. Surface sediments collected from Richards Bay Harbour and surrounding areas indicate that OCP contamination in the region is widespread. Total concentrations (∑OCP) in surface samples ranged from 135 to 1020 ng g^-1, with hexachlorocyclohexanes (∑HCH; 35-230 ng g^-1) and dichlorodiphenyltrichloroethanes (∑DDT; 12-350 ng g^-1) the dominant contaminant groups detected. Metabolite isomeric compositions indicate that the presence of aldrin and endosulfan likely result from historical agricultural usage, while recent input of γ-HCH, heptachlor, and endrin may be linked to the illegal use of old pesticide stockpiles. Total DDT concentrations were dominated by p,p'-DDT (80 ± 64 ng g^-1), which was attributed to its ongoing use in malaria vector control in the region. A ²¹⁰Pb-dated sediment core revealed that OCP input to the local environment increased dramatically from relatively low concentrations in the mid-1940s (∑OCP, 355 ng g^-1) to peak levels (∑OCP, 781 ng g^-1) in the 1980s/1990s. An overall decrease in ∑OCP concentration from the mid-2000s is likely related to restrictions on use following the Stockholm Convention in 2004. Despite current restrictions on use, OCP concentrations exceeded sediment quality guidelines in the vast majority of cases, raising concerns for protected estuarine and mangrove habitats in the area, as well as for local fishing and farming communities.

Comprehensive non-target screening of biomagnifying organic contaminants in the Baltic Sea food web

High-resolution mass spectrometry (HRMS) based non-target screening (NTS) is a powerful approach for the simultaneous determination of multiple environmental contaminant classes in complex biota samples. In this study, trophic biomagnification factor (TMF) directed NTS was performed to find and (tentatively) identify known, emerging, and new chemical contaminants that are persistent and biomagnify in Baltic Sea biota. The investigated food web included seven species: one filter feeder (blue mussel, Mytilus edulis), two fish (eelpout, Zoarces viviparous; herring, Clupea harengus), two marine mammals (harbor porpoise, Phocoena phocoena; grey seal, Halichoerus grypus) and two birds (guillemot, Uria aalge; white-tailed sea eagle, Haliaeetus albicilla). The NTS procedure included extraction with organic solvent mixtures, two-step high-resolution gel permeation chromatography clean-up, Florisil® fractionation, gas chromatography (GC) HRMS analysis in electron ionization (EI) and electron capture negative ion chemical ionization (ECNI) modes, and NTS data processing. The latter was performed differently for the EI and ECNI data: the EI data were treated using a flexible and highly automated TMF-directed NTS workflow, whereas the ECNI data were treated with a simpler and less automated workflow that specifically screened for brominated compounds. The two workflows collectively revealed biomagnification (statistically significant TMF values) of >250 tentatively identified compounds, including legacy persistent organic pollutants (POPs), such as PCBs and PCB-related compounds, DDT and its metabolites, and organochlorine pesticides (OCPs), contaminants of emerging concern (CECs), and halogenated natural products (HNPs). Among the tentatively identified CECs, nine have not previously been reported in environmental biota samples. These included four polymer additives (used as antioxidants, rubber additives or plasticizers) and two cosmetic product additives (ethyl myristate and isopropyl palmitate). The CECs should be prioritized for future structure verification and quantification using reference standards.

Distribution characteristics, sources, and risk assessment of organochlorine pesticides in the Fildes Peninsula and Adelaide Island

This work analyzed the distribution characteristics, sources, and corresponding environmental risks of 10 organochlorine pollutants (OCPs) in soil samples from 13 stations on the Fildes Peninsula and Adelaide Island in Antarctica in 2020. Results showed that the total amount of OCP residues in the study area ranged from N.D. to 2.66 ng·g^-1 with an average concentration of 0.90 ng·g^-1. Six organochlorine pesticides were detected, and the residue level of DDTs was slightly lower than that of HCHs. The residues of HCHs were mainly γ-HCH and those of DDTs were mainly O, P'-DDT. Source analysis revealed that the residues mainly originated from atmospheric transport and human activities. Environmental risk analysis showed that in the study area, the residues of HCHs and DDTs were present at low levels, and their ecological risk was low.

Occurrence and risk assessment of endocrine-disrupting compounds in fish muscle: The case study of the Douro River estuary (North East Atlantic Ocean)

This work was focused on evaluating the occurrence of endocrine-disrupting compounds (EDCs) in fish muscles, such as bisphenol analogues, personal care products, including some UV-filters and musk fragrances, and selected pesticides. A total of 238 muscle samples of three fish species (Platichthys flesus, Mugil cephalus, and Dicentrarchus labrax) of an important estuary ending in the North East Atlantic Ocean (Douro River estuary, Portugal), in different seasons of the year, was analysed. M. cephalus was the species with a greater occurrence of contaminants, mainly in fishes collected during the spring. Bisphenol A was the main bisphenol analogue detected with an average content of 23.1 μg/kg wet weight (w.w.). Among chemicals used in personal care products, galaxolide, tonalide, and 2-ethylhexyl salicylate, were the most often found, being present in 15.9% (2.2-538.4 μg/kg w. w.), 4.6% (1.1-57.8 μg/kg w. w.) and 3.4% (3.9-56.1 μg/kg w. w.) of the samples, respectively. About 14% of the samples contained residues of at least one pesticide, being alachlor, aldrin, p,p'-DDT, permethrin, and prochloraz the main chemicals observed, varying from 0.1 μg/kg w. w. (p,p'-DDT) to 37.8 μg/kg w. w. (prochloraz). The daily intake estimates of the most frequent EDCs found in the fish muscles suggested that there are no health concerns, based on the recommended weekly consumption of fish for adults.

Predicting the regional contamination evolution of DDT for 100-years with a new gridded spatial and dynamic multimedia fate model

In 1996 high dichlorodiphenyltrichloroethane (DDT) concentrations were found in Lake Maggiore (Italy) fish and sediments. DDT was produced by a chemical company located in a subalpine valley (Ossola valley, Piedmont Region, Italy), and ended up in the Toce River, a tributary of Lake Maggiore. In the area surrounding the chemical plant, high DDT concentrations in soil and vegetation were found after subsequent investigations. The quantification of the release from contaminated soil and the following migration toward downwind areas, deposition to the soil, and further evaporation plays an important role in understanding future DDT trends in soil and the atmosphere. To study this phenomenon, soil, and vegetation from Ossola Valley were monitored in 2001 and 2011. The concentration values obtained (soils: 0.05 to 1 μg/g; vegetation 2-100 ng/g), allowed to reconstruct the contamination gradient in the valley and were used to develop and calibrate a spatially resolved multimedia fugacity model. The model accounts for spatial and temporal dynamicity of environmental characteristics such as wind speed and direction, variable air compartment height etc., and simulates the fate and transport of chemicals on a local scale. The dynamic emission of DDT (about 13,000 kg for the 50 y production time) to the air was estimated and utilized for a 100-year simulation (from 1948 to 2048). The results obtained allowed to understand the temporal and spatial pattern of DDT contamination for a long period at a local scale as well as the potential contribution as a source potentially affecting sites at larger distances.

Legacy and new chlorinated persistent organic pollutants in the rivers of south India: Occurrences, sources, variations before and after the outbreak of the COVID-19 pandemic

During pre-pandemic time, organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs) were investigated in the surface water of Periyar River (PR) and Bharathappuzha River (BR) in Ernakulam and Malappuram districts of Kerala, respectively and Adyar River (AR) and Cooum River (CR) in Chennai district of Tamil Nadu. After the outbreak of COVID-19 pandemic, variation in OCPs and PCBs were evaluated for AR and CR. Dominance of β-HCH and γ-HCH in south Indian rivers indicate historical use of technical HCH and ongoing use of Lindane, respectively. In > 90 % sites, p,p'-DDT/ p,p'-DDE ratio was < 1, indicating past DDT usage. However during the outbreak of the COVID-19 pandemic, elevated p,p'-DDT in AR and CR reflects localized use of DDT possibly for vector control. Similarly, during the first wave of pandemic, over a 100-fold increase in PCB-52 in these rivers of Chennai mostly via surface run-off and atmospheric deposition can be reasoned with open burning of dumped waste including added waste plastic in the solid waste stream. On contrary, a significant (p < 0.05) decline of dioxin-like PCBs level, suggests lesser combustion related activities by the formal and informal industrial sectors after the lockdown phase in Tamil Nadu. Eco-toxicological risk assessment indicated a higher risk for edible fish in PR due to endosulfan.

Freely dissolved organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs) along the Indus River Pakistan: spatial pattern and risk assessment

Freely dissolved OCPs and PCBs were measured by using polyethylene passive samplers at 15 sites during 2014 throughout the stretch of the Indus River to investigate the spatial pattern and risk assess. Levels (pg/L) of dissolved ∑OCPs and ∑PCBs ranged from 34 to 1600 and from 3 to 230. Among the detected OCPs, dissolved DDTs (p,p'-DDE, followed by p,p'-DDT) predominated with levels of 0.48 to 220 pg/L. The order of occurrence for other studied OCPs was as follows: HCB, endosulfans, chlordanes, and HCHs. Spatially, dissolved (pg/L) ∑OCPs varied (p < 0.05) as the following: surface water of the alluvial riverine zone (ARZ) showed the highest levels (114) followed by the frozen mountain zone (FMZ) (52.9), low-lying zone (LLZ) (28.73), and wet mountain zone (WMZ) (14.43), respectively. However, our zone-wise PCB data did not exhibit significant differences (p > 0.05). Principal component analysis/multilinear regression results showed pesticide usage in the crop/orchard fields and health sector, electric and electronic materials, and widespread industrial activities as the main source of OCPs and PCBs along the Indus River. Our results showed that OCPs and PCBs contaminated water intake, playing an important role towards the considerable cancer/non-cancer risk (HI and CR values) along the Indus River Flood-Plain.

Global qualitative and quantitative distribution of micropollutants in the deep sea

Micropollutants (MPs) include a wide range of biological disruptors that can be toxic to wildlife and humans at very low concentrations (<1 μg/L). These mainly anthropogenic pollutants have been widely detected in different areas of the planet, including the deep sea, and have impacts on marine life. Because of this potential toxicity, the global distribution, quantity, incidence, and potential impacts of deep-sea MPs were investigated in a systematic review of the literature. The results showed that MPs have reached different zones of the ocean and are more frequently reported in the Northern Hemisphere, where higher concentrations are found. MPs are also concentrated in depths up to 3000 m, where they are also more frequently studied, but also extend deeper than 10,000 m. Potentially toxic metals (PTMs), polychlorinated biphenyls (PCBs), dichlorodiphenyltrichloroethane (DDTs), organotins, and polycyclic aromatic hydrocarbons (PAHs) were identified as the most prevalent and widely distributed MPs at ≥200 m depth. PTMs are widely distributed in the deep sea in high concentrations; aluminum is the most prevalent up to 3000 m depth, followed by zinc and copper. PCBs, organotins, hexachlorocyclohexanes (HCHs), PAHs, and phenols were detected accumulated in both organisms and environmental samples above legislated thresholds or known toxicity levels. Our assessment indicated that the deep sea can be considered a sink for MPs.

Are fur farms a potential source of persistent organic pollutants or mercury to nearby freshwater ecosystems?

Farming of carnivorous animals for pelts potentially contaminates nearby ecosystems because animal feed and waste may contain persistent organic pollutants (POPs) and metals. Mink farms in Nova Scotia (NS), Canada, provide mink with feed partially composed of marine fish meal. To test whether mink farms potentially contribute contaminants to nearby lakes, we quantified organochlorine pesticides (OCP), polychlorinated biphenyls (PCB), and total mercury (THg) in mink/aquaculture feed, waste, and sediment collected from 14 lakes within rural southwest NS where mink farms are abundant and have operated for decades. Mercury, PCBs, dichlorodiphenyltrichloroethane (DDT), hexachlorocyclohexane (HCH), and dieldrin were present in mink/aquaculture feed and mink waste, indicating they are potential contaminant sources. Lakes with mink farms in their catchment exhibited significantly higher THg_flux than lakes downstream of mink farming activity and reference lakes (p < 0.0001) after the intensification of mink farming in 1980, indicating mink farming activity is likely associated with increased lacustrine THg_flux. Sedimentary ƩPCB_flux was elevated in lakes with mink farms in their catchments, suggesting possible PCB contributions from mink farming, local agriculture, and atmospheric deposition. Elevated ƩDDT in lakes near mink farms relative to reference lakes suggests a possible enrichment related to mink farming, although mixed land use and historical DDT usage related to forestry in the region complicates DDT source attribution. Maximum dieldrin_flux and HCH_flux in lake sediment occurred coeval with peak worldwide usage in the 1970s and are unlikely to be associated with local mink farming. Lakes with mink farming activities in their catchments were associated with increased THg_flux, ƩPCB_flux, and possibly ƩDDT_flux, suggesting a possible connection between marine fish meal, fur farms, and aquatic ecosystems in NS.

Distribution, sources, and ecological risk assessment of HCHs and DDTs in water from a typical coal mining subsidence area in Huainan, China

Coal mining subsidence areas are a special and widespread ecosystem in China and many developing countries in the world. However, limited research has focused on HCHs and DDTs in coal mining subsidence areas. Investigating the concentration, distribution, and sources of HCHs and DDTs at the Yangzhuang coal mining subsidence area in Huainan, China, is the object of this study. Water samples from different depths were collected from this region to detect and analyze HCHs and DDTs using gas chromatography-mass spectrometry. The result showed that the concentrations of HCHs and DDTs increased with increasing water depth, and the average concentrations of HCHs and DDTs in the top (T-layer), middle (M-layer), and bottom (B-layer) layers were 152, 169, and 182 ng∙L^-1, respectively. Spatial distribution of HCH and DDT concentrations in the study area revealed that the concentrations gradually decreased in the direction of water flow, and the highest concentration was observed at the entrance of the Nihe River. The T-layer was easily influenced by environmental and human activities, while the M-layer and B-layer were mainly influenced by sediment. Using principal component analysis and diagnostic ratios, we found that HCHs and DDTs in the study area mainly originated due to natural and human activities (such as pesticide use). Hexachlorocyclohexanes (HCHs) were mainly derived from lindane, and dichlorodiphenyltrichloroethanes (DDTs) mainly originated due to the recent agricultural use of dicofol; both of these are directly related to agricultural activities. Based on a comparison of reported concentrations of HCHs and DDTs in the rivers and lakes throughout China, we found that the overall ecological risk of HCHs and DDTs in the study area was elevated. The results are important for further understanding the transfer characteristics of HCHs and DDTs as well as the ecological health of the water in coal mining subsidence areas.

Spatiotemporal evaluation of organochlorine pesticide residues in bottom sediments of the Rio de Ondas hydrographic basin, western Bahia, Brazil

The Rio de Ondas Hydrographic Basin (ROHB), Bahia state, Brazil, is located in a region with abundant water resources and is highly impacted by intense agricultural activity. In such a scenario, the use of organochlorine pesticides can represent a potential risk to the aquatic environments, due to their persistence, high bioaccumulation capacity, and high toxicity. Thus, organochlorine pesticide residues in bottom sediment samples from rivers on eighteen sites distributed along the ROHB in the dry and rainy periods were analyzed by gas chromatography coupled with mass spectrometry. The validated method showed no matrix effect, recoveries ranging from 82% (β-HCB) to 118% (DDD), limits of detection between 0.003 ng g^-1 (α-HCH) and 0.011 ng g^-1 (DDT), limits of quantification of 0.010 ng g^-1 (α-HCH) to 0.036 ng g^-1 (DDT), repeatability with the highest relative standard deviation of 0.97% (α-hexachlorocyclohexane at 2.000 ng g^-1), and inter-day precision ranging from 10% (aldrin at 0.050 ng g^-1 and 0.600 ng g^-1 and α-endosulfan at 0.600 ng g^-1) to 25% (β-endosulfan at 0.050 ng g^-1). Although most compounds were banned since 1985, it was observed that their residues were widely distributed in the ROHB, with the total concentrations varying from 3.242 ng g^-1 (P02) to 12.052 ng g^-1 (P17) and from 0.313 ng g^-1 (P14) to 30.861 ng g^-1 (P13) in the dry and rainy periods, respectively, which may be related to historical contamination and/or prohibited use. Moreover, the spatiotemporal variation showed the highest concentrations of organochlorine pesticide residues in the rainy season, coinciding with the planting period.

Evaluation of residual level and distribution characteristics of organochlorine pesticides in agricultural soils in South Korea

In this study, we evaluated the residual levels and distribution characteristics of 10 organochlorine pesticides (OCPs) in the soil of agricultural lands (paddy field, vegetable field, and orchard, n = 150) nationwide. As a result of the investigation, 3-10 types of OCPs were detected in combination in 144 locations (96%) of the total 150 locations. Among those OCPs, dichlorodiphenyltrichloroethane (DDT) and endosulfan were detected in high amounts. The geometric mean concentrations of DDT and endosulfan were ∑DDT 0.31 ng g^-1 (ND-2187.18 ng g^-1) and ∑endosulfan 0.33 ng g^-1 (ND-312.68 ng g^-1), respectively. OCP concentrations were generally higher in orchards than in other agricultural fields due to a large amount of pesticides used. DDT in two orchards was detected at 2187.18 ng g^-1 and 1061.78 ng g^-1, exceeding the levels stated in the Canadian DDT Soil Quality Guidance (SQG, 700 ng g^-1). The result of applying the isomer ratio to evaluate the recent or past use of DDT, endosulfan, and hexachlorocyclohexane (HCH), which had a high detection rate, showed that it could be attributable to historical usage. DDT and HCH showed statistically similar residual distribution patterns; however, endosulfan did not show a clear correlation with DDT and HCH due to the effect of its recent use. Thus, the results of evaluation of OCP residual levels and distribution characteristics can be used for the soil management policy of OCPs in agricultural lands in Korea.

Occurrence, source, and ecological risk assessment of organochlorine pesticides and polychlorinated biphenyls in the water-sediment system of Hangzhou Bay and East China Sea

The pollution characteristics, potential sources, and potential ecological risk of organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs) were investigated in the Hangzhou Bay (HZB) and East China Sea (ECS). Total OCPs concentration ranged from 2.62 to 102.07 ng/L and 4.41 to 75.79 μg/kg in the seawater and sediment samples, with PCBs concentration in the range of 0.40-51.75 ng/L and 0.80-45.54 μg/kg, respectively. The OCPs were positively correlated with nutrients, whereas PCBs presented a negative correlation. The newly imported dichlorodiphenyltrichloroethane (DDT) in HZB is mainly the mixing of technical DDT and dicofol sources. The PCB source composition is more likely related to the mixture of Kanechlor 300, 400, Aroclor 1016, 1242, and Aroclor 1248. Risk assessment results indicate that OCPs posed low risk in seawater. The potential risk of DDTs in the sediments is a cause of concern.

Organochlorine pesticides in riparian soils and sediments of the middle reach of the Huaihe River: A traditional agricultural area in China

Distributions, souces, ecological risks as well as environmental behaviors of 20 organochlorine pesticides (OCPs) in riparian soils and sediments of the middle reach of the Huaihe River, a traditional agricultural area of China, were investigated. ∑OCPs in riparian soils and sediments were 1.8-63 ng g^-1 (mean = 19 ± 12 ng g^-1) and 1.2-9.9 ng g^-1 (mean = 3.0 ± 1.8 ng g^-1), respectively. HCHs were the dominant OCPs in both soils and sediments, while high concentrations of ∑HEPTs and ∑DDTs were also detected in some soils and sediments. No correlations were found between concentrations of OCPs and organic matter contents in both soils and sediments. Based on the source analysis, most OCPs in the riparian soils were mainly from historical residues, such as historical usage of technical HCH, DDT, chlordane and endosulfan. OCPs in sediments were influenced not only by surface runoff by also by other factors, e.g. in-situ contamination (DDT-containing antifouling paints in ships) and/or hydraulic transport from some tributaries. Some never-used OCPs, such as heptachlor and aldrin, were widely detected in soils and sediments. This might be attributed to some unknown usages or long-range atmospheric transport of them from other source regions. Ecological risk analysis suggested that DDTs and HCHs in soils would not lead to an adverse effect on soil ecological environment as well as agricultural production, and OCP residues in sediments also would not pose a threat to the sediment-dwelling organisms.