DDT Concentrations Research Articles

Residual, Enrichment and Health Risk Assessment of Hexachlorocyclohexane and Dichlorodiphenyltrichloroethane in Muscle of Cultured Common Carp

Common carp (Cyprinus carpio) is extensively cultured and widely consumed in Heilongjiang Province, China. Due to the proximity of freshwater ponds to agricultural cultivated areas, these aquatic systems are inevitably influenced by the historical application of organochlorine pesticides (OCPs), due to their prolonged half-life and resistance to degradation. Gas chromatography-tandem mass spectrometry (GC-MS/MS) was utilized to quantify the levels of hexachlorocyclohexane (HCHs) and dichlorodiphenyltrichloroethane (DDTs) in the muscle tissue of cultured common carp. This study examined the enrichment characteristics of HCHs and DDTs in fish muscle, as well as their correlation with sediment and associated risk assessments. The results showed that the residual levels of HCHs and DDTs in fish muscle ranged from 0.387 μg·kg−1 to 3.418 μg·kg−1 and from 0.114 μg·kg−1 to 0.420 μg·kg−1, respectively. They were all below the maximum residue limits specified in GB 2763-2021 (HCHs: 100 μg·kg−1, DDTs: 500 μg·kg−1). The concentrations of HCHs and DDTs in sediment were found to be lower than those in muscle tissue. Notably, the concentrations of HCHs were higher than those of DDTs in both muscle and sediment. Among the HCHs, γ-HCH was the predominant residual substance, contributing a significant proportion of 42.16% to 86.47%. No significant residues of DDT derivatives were detected. A significant correlation was observed between the concentrations of HCHs and DDTs in the muscle tissue and those present in the sediment (p < 0.01). The health risk assessment indicated that both the carcinogenic and non-carcinogenic risks associated with OCPs from common carp muscle and sediment were within acceptable limits. Therefore, it was recommended to regulate fish consumption during the breeding period.

Background of persistent organic pollutants in estuarine sediments from the Marajó Island, an Amazonian environmental protection area for sustainable use.

Marajó Island, an environmental protection area for sustainable use in the Brazilian Amazon, was the first region in Brazil to apply the pesticide DDT, a persistent organic pollutant (POP), to control malaria outbreaks. This study investigated background levels of various POPs, including o,p'- and p,p'-DDT and their primary metabolites (o,p'- and p,p'-DDE, o,p'- and p,p'-DDD), as well as hexachlorocyclohexane (α-, β-, γ-, δ-HCH), using estuarine surface sediments and sediment cores from areas influenced by urbanization and agriculture. All samples were collected during the dry season (September 2014). Surface sediments exhibited ΣDDT concentrations up to 2.71ngg⁻1, with isomeric ratios indicating past DDT application and contributions from dicofol. Sediment profiles revealed alternating aerobic and anaerobic degradation processes of DDT. Other organochlorinated contaminants were not detected. The presence of γ-HCH as the main isomer (0.24 to 0.90ngg⁻1) in surface samples suggests recent lindane application as a wood preservative or cattle parasite treatment. A dated sediment core revealed historical contamination of early DDT tests in the Amazon during the mid-1940s. Increasing ΣDDT concentrations (up to 12.3ngg⁻1) were identified in the 1970s, coinciding with the intensification of DDT use for public health campaigns, which lasted until 2009 and reached the highest ΣDDT flux. Legal restrictions on the use and commercialization of POPs, along with natural degrading processes, likely led to decreased accumulation and limited ecological risks. Furthermore, the low concentrations of POPs suggested biodegradation and dispersion from northeast to southeast.

The persistent DDT footprint of ocean disposal, and ecological controls on bioaccumulation in fishes

Globally, ocean dumping of chemical waste is a common method of disposal and relies on the assumption that dilution, diffusion, and dispersion at ocean scales will mitigate human exposure and ecosystem impacts. In southern California, extensive dumping of agrochemical waste, particularly chlorinated hydrocarbon contaminants such as DDT, via sewage outfalls and permitted offshore barging occurred for most of the last century. This study compiled a database of existing sediment and fish DDT measurements to examine how this unique legacy of regional ocean disposal translates into the contemporary contamination of the coastal ocean. We used spatiotemporal modeling to derive continuous estimates of sediment DDT contamination and show that the spatial signature of disposal (i.e., high loadings near historic dumping sites) is highly conserved in sediments. Moreover, we demonstrate that the proximity of fish to areas of high sediment loadings explained over half of the variation in fish DDT concentrations. The relationship between sediment and fish contamination was mediated by ecological predictors (e.g., species, trophic ecology, habitat use), and the relative influence of each predictor was context-dependent, with habitat exhibiting greater importance in heavily contaminated areas. Thus, despite more than half a century since the cessation of industrial dumping in the region, local ecosystem contamination continues to mirror the spatial legacy of dumping, suggesting that sediment can serve as a robust predictor of fish contamination, and general ecological characteristics offer a predictive framework for unmeasured species or locations.

Association Between Prenatal Exposure to Organochlorine Pesticides and Telomere Length in Neonatal Cord Blood.

Objectives: Environmental exposure may affect the telomere length (TL) of newborns, which is considered as an early biomarker indicating susceptibility for later life diseases. However, the effects of prenatal organochlorine pesticide (OCP) exposure on newborn TL remain unclear. This study aimed to investigate the association between prenatal exposure levels of OCPs during pregnancy and TL in neonatal cord blood. Methods: A total of 168 mother-infant pairs from a birth cohort in Wuhan, China, were included this study. The concentrations of hexachlorocyclohexanes (HCHs, including β-HCH, α-HCH, and γ-HCH), p,p'-dichlorodiphenyltrichloroethane (p,p'-DDT) and its metabolites (p,p'-dichlorodiphenyldichloroethane, p,p'-DDD; p,p'-dichlorodiphenyldichloroethylene, p,p'-DDE) were measured in cord blood. The associations between the OCPs and the TL in newborns were analyzed by a generalized linear regression model. Stratified analyses by newborn sex, maternal gestational weight gain, and pregnancy body mass index (BMI) were performed to evaluate if the associations were modified by these factors. Results: The detection rates of various OCPs ranged from 50.9% to 100.0%. The median concentration of p,p'-DDE was the highest (33.90 ng/g lipid), followed by β-HCH (8.67 ng/g lipid), and the median concentrations of the other OCPs were between 0.12 and 0.33 ng/g lipid. Among the all newborns, a two-fold increase in the γ-HCH concentration in the cord blood was significantly associated with a 0.024 (95% CI: -0.041, -0.007) decrease in the TL. After stratification by newborn sex, the inverse association between γ-HCH and the TL was only statistically significant in boys, but not in girls (P for interaction <0.05). In addition, after stratification by pre-pregnancy BMI, β-HCH and p,p'-DDT concentrations were significantly associated with a decreased TL in the overweight pre-pregnancy BMI group [-0.111 (95% CI: -0.203, -0.018) and -0.036 (95% CI: -0.049, -0.023), respectively]. Conclusions: Prenatal exposure to OCPs during pregnancy was associated with a decreased neonatal telomere length, which may be affected by the newborn sex and pre-pregnancy BMI. These findings may provide new insights into the mechanisms underlying OCP-induced adverse health effects.

Legacy persistent organic pollutants among multiple cetacean species in the Northwest Atlantic

The historical contamination of eastern Canadian shelf waters remains an ongoing concern, predominantly stemming from anthropogenic discharges in the Great Lakes region. Although legacy persistent organic pollutants (POPs) were banned decades ago, it remains unclear whether their concentrations have sufficiently decreased to safer levels in cetaceans that feed in the continental shelf waters of the northwestern Atlantic. This study compares polychlorinated biphenyl (PCB) and organochlorine pesticide (OC) accumulation in six cetacean species sampled in the Northwest Atlantic from 2015 to 2022. We assessed the influence of relative trophic level and foraging habitat preferences on POP accumulations among species using stable isotopes and fatty acids as dietary tracers. We further identified the species most susceptible to the effects of these contaminants. Killer whales (Orcinus orca) exhibited the highest PCB (∼100 mg/kg lw) and OC concentrations, followed by other odontocetes, with lowest concentrations in mysticetes. Stable isotope analysis revealed an unexpected lack of correlation between δ15N values and contaminant levels. However, there was a positive correlation between δ13C values and POP concentrations. Cetaceans foraging on pelagic prey species, as indicated by elevated proportions of the FA markers 22:1n11 and 20:1n9, had lower contaminant loads compared to cetaceans with benthic/coastal FA signatures. PCB and DDT (dichlorodiphenyltrichloroethane) concentrations are lower now in most cetacean species than in the 1980s and 1990s, likely due to regulatory measures restricting their production and use. Although current PCB concentrations for most species are under the thresholds for high risks of immune and reproductive failure, concentrations in killer whales exceed all established toxicity thresholds, underscoring the need for further action to reduce sources of these contaminants to the continental shelf waters of the northwestern Atlantic.

Modern problems of Ukraine's ecology: agricultural pollutants and the quality of drinking water in the city of Kyiv

Considered modern problems of Ukraine's ecology. The problem “influence of agriculture on the quality of underground water” is considered in detaile. In 1998-2002, 163 analyzes of underground waters of the aquifer of Cenomanian sediments and the aquifer of Jurassic sediments in the city of Kyiv for the content of persistent chlorine-organic pesticides: DDT and its metabolites, hexachlorocyclohexane (HCCH) and its isomers, aldrin, heptachlor and the fluor-containing pesticide treflane were carried out by the gas-chromatographic method. In the water of the aquifer of Cenomanian sediments and the aquifer of Jurassic sediments of the city of Kyiv, the average concentration of DDT was at the level of 10-5 mg/dm3. According to our calculations for the year 2024, the concentration of the amount of DDT in the drinking groundwater of the city of Kyiv has decreased by 2-3 orders of magnitude, depending on natural conditions. This indicates that there no new inputs of DDT to natural ecosystems, and retrospective contamination is gradually decreasing. The need to conduct fundamental research of establishing concentrations of new pesticides in groundwater, developing criteria for assessing the danger of co-presence of pesticides of various classes of chemical compounds in groundwater and other natural objects remains relevant. In 2023-2024, 58 wells were examined for the quality of drinking water in Kyiv.

Temporal trends (1972-2017) and spatial differences of persistent halogenated aromatic hydrocarbons in osprey eggs in Finland.

Time trends and regional differences of polychlorinated dibenzo-p-dioxins and -furans (PCDD/Fs), polychlorinated biphenyls (PCBs), polychlorinated naphthalenes (PCNs), DDTs, polybrominated biphenyls (PBBs) and polybrominated diphenylethers (BDEs) were studied in unhatched osprey eggs collected by bird ringers in 1972-2017 from four areas in Finland. Two study areas were from Baltic Sea, Northern Quark and Finnish Archipelago Sea, while the two others were inland lake areas, eutrophicated Lake Vanajanselkä affected by industrial emissions, and Pristine SW Lake Area. The highest concentrations of most compound groups were in Lake Vanajanselkä consistent with high emissions, the predominance of bream as a prey, and higher concentrations in bream compared to other prey fish. Concentrations of all chlorinated compounds decreased significantly in all study areas. Average annual decreases were ∑PCDD/F 2.3-4.9%, ∑PCB 2.2-4.2%, ∑PCN 2.6-7.0% and ∑DDT 7.1-9.5%, primarily in line with decreased levels in prey fish. From 1972 PBBs and BDEs increased significantly until 1990s declining rapidly thereafter. PCDD/F congener profile was dominated by 2,3,4,7,8-PeCDF, except in Lake Vanajanselkä by 1,2,3,6,7,8-HxCDD. PCB congener profile was dominated by PCB 153 in all study areas, followed by PCB 180 and PCB 138. Among dioxin-like compounds PCBs contributed 82%, PCDDs 14% and PCDFs 4% to toxic equivalent quantity (∑TEQ). PCB 126 contributed most to ∑TEQ, followed by 1,2,3,7,8-PeCDD. BDE 47 being the dominant BDE congener, followed by BDE 100. ∑DDT concentrations were relatively similar across all study areas, with DDE contributing about 90%. Productivity of chicks per active nest was significantly decreased in Lake Vanajanselkä, and the likely explanation is embryotoxicity of dioxin-like compounds. It is plausible that dioxin-like compounds influenced embryonic survival among highly exposed ospreys prior to 2010, especially in Lake Vanajanselkä and Northern Quark. However, decreased survival due to DDE-induced eggshell thinning seems unlikely after 1985, and BDE levels were below those potentially causing adverse effects.

Impaired energy expenditure following exposure to either DDT or DDE in mice may be mediated by DNA methylation changes in brown adipose.

The insecticide dichlorodiphenyltrichloroethane (DDT) and its persistent metabolite, dichlorodiphenyldichloroethylene (DDE), have been associated with increased adiposity and obesity in multiple generations of rodents and humans. These lipophilic pollutants accumulate in adipose tissue and appear to decrease energy expenditure through the impairment of thermogenesis in brown adipose tissue (BAT). We hypothesized that impaired thermogenesis is due to persistent epigenetic modifications of BAT. To address this, we exposed C57BL/6 J mice to DDT or DDE from gestational day (GD) 11.5 to postnatal day (PND) 5, evaluated longitudinal body temperature, and performed reduced representation bisulfite sequencing and RNA sequencing of BAT from infant and adult offspring. Exposure to DDT or DDE reduced core body temperature in adult mice, and differential methylation at the pathway and gene level was persistent from infancy to adulthood. Furthermore, thermogenesis and biological pathways essential for thermogenic function, such as oxidative phosphorylation and mechanistic target of rapamycin kinase (mTOR) signaling, were enriched with differential methylation and RNA transcription in adult mice exposed to DDT or DDE. PAZ6 human brown preadipocytes were differentiated in the presence of DDT or DDE to understand the brown adipocyte-autonomous effect of these pollutants. In vitro exposure led to limited changes in RNA expression; however, mitochondrial membrane potential was decreased in vitro with 0.1 µM and 1 µM doses of DDT or DDE. These results demonstrate that concentrations of DDT and DDE relevant to human exposure have a significant effect on thermogenesis, the transcriptome, and DNA methylome of mouse BAT and the mitochondrial function of human brown adipocytes.

EFFECTS OF PESTICIDES RECIDUES ON TILAPIA ZILLII, SEDIMENT AND SURFACE WATER OF ERINLE DAM AND RIVER OSUN IN OSUN STATE

This study investigates the effects of selected pesticides on the health of aquatic ecosystems and humans in Erinle Dam and River Osun, Osun State, Nigeria. Focusing on Tilapia zillii, a commonly consumed fish in the region, the research assesses the potential health risks posed by pesticides found in the water, sediments, and fish tissues. Samples were collected following APHA guidelines and tested for pesticides like DDT, Heptachlor, Dieldrin, Aldrin, and Chlorpyrifos. The findings revealed high levels of DDT and Chlorpyrifos in both the water and fish, with Erinle Dam showing higher concentrations than River Osun. Specifically, DDT levels in River Osun's water averaged 199.08mg/kg, while Erinle Dam had 271.58mg/kg. Dieldrin and Chlorpyrifos also showed high concentrations, with Heptachlor and Aldrin absent in the water samples from both sites. Fish tissue analysis indicated higher pesticide levels in specimens from Erinle Dam compared to River Osun. DDT and Chlorpyrifos concentrations were notably high, while Dieldrin, Aldrin, and Heptachlor were present in lower amounts. Similarly, sediment analysis showed Erinle Dam with higher pesticide concentrations, particularly for DDT, Dieldrin, and Chlorpyrifos, while Heptachlor and Aldrin were absent.Overall, the study highlights significant pesticide contamination in Erinle Dam and River Osun, posing health risks to local fish consumers and indicating a need for stringent pesticide regulation and monitoring in the region.

Organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs) distribution, origins, and risk evaluation in the Egyptian Mediterranean coast sediments.

A study was conducted on 31 surface sediments located in different sectors of the Egyptian Mediterranean coast. The sediments were analyzed for their pollution levels of organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs). The sediments were collected from various depths in harbors, coastal lakes, bays, and lagoons, covering the southeastern Mediterranean of the Nile Delta region. The study aimed at determining the distribution, origin, and potential ecological impact of OCP and PCB pollutants. The researchers used the SRM method of GC-MS/MS to measure the concentration of 18 PCBs and 16 OCPs residues. The study found that the total concentration of OCPs in the samples ranged from 3.091 to 20.512 ng/g, with a mean of 8.749 ±3.677 ng/g. The total concentration of PCB residues ranged from 2.926 to 20.77 ng/g, with a mean of 5.68 ±3.282 ng/g. The concentration of DDTs exceeded the effect range low (ERL) (1.00) and threshold effect level (TEL) (1.19) in several stations, but it was still below the effect range median (ERM) (7.00) and the probable effect level (PEL) (4.77). This indicates a low ecological risk. The principal component analysis (PCA) was also conducted to determine the sources of all pollutants in the sediment. The PCA showed significant correlations between the concentrations of Gama-HCH and Beta-HCH (0.741), suggesting similar sources. PRACTITIONER POINTS: OCPs and PCBs residues were analyzed in the sediment of the southeastern Mediterranean. The concentration, existence, and causes of OCPs and PCBs were investigated. OCPs and PCBs ecological risk and ecotoxicological calculation were investigated in detail. Cluster analysis, PCA, and correlation coefficient were also investigated.

Spatial and cumulative organochlorine and mercury exposure assessments in Steller Sea lions of Alaska: Emphasizing pups

Steller sea lions (SSL) are sentinels for monitoring environmental contaminants in remote areas of the Aleutian Islands, Alaska. Therefore, concentrations of several organochlorines (OCs) were measured in blood from 123 SSL pups sampled from 3 regions; the western Aleutian Islands (WAI), central Aleutian Islands (CAI), and the central Gulf of Alaska. Blood, blubber, and milk from 12 adult female SSL from WAI, CAI and southeast Alaska also were analyzed. Findings included the following. SSL pups had higher concentrations of some OCs and mercury (Hg) on rookeries in the WAI than those more easterly. Pups had significantly higher blood concentrations of many OC classes than adult females sampled within the same region; some pups had PCB concentrations exceeding thresholds of concern (∑PCBs >8600 ng/g lw). ∑PCB concentration in pup whole blood was positively correlated with the trophic marker, δ15N within the regions sampled, along with two PCB congeners (PCB138 and PCB153). This suggests that the dams of pups with higher ∑PCBs, PCB138, and PCB153 concentrations were feeding on more predatory prey. Adult female blubber ∑DDT and hexachlorocyclohexane concentrations were also positively correlated with δ15N values. Several pups (mostly from WAI) had blood Hg concentrations and/or blood PCB concentrations (surrogate for overall OC exposures) of concern. The finding that WAI SSL pups have been exposed to multiple contaminants calls for future investigation of their cumulative exposure to a mixture of contaminants especially their transplacental and then transmammary exposure routes.

Sediment-water exchange and risk assessment of pesticidal persistent organic pollutants in Bharathappuzha and Periyar Riverine region along the Arabian Sea.

Considering the extensive agricultural practices along the perennial rivers, viz. Periyar and Bharathappuzha of Kerala in the southwest coast of India, the first comprehensive surveillance of new and legacy organochlorine pesticides (OCPs) in surface sediment was conducted. Further, the sediment-water exchange fluxes have been elucidated. Mean concentrations of total HCH, DDT and endosulfan were 0.84ng/g, 0.42ng/g and 0.30ng/g for Bharathappuzha Riverine sediment (BRS) and 1.08ng/g, 0.39ng/g and 0.35ng/g for Periyar Riverine sediment (PRS). The dominance α-HCH and β-HCH isomers in PRS and BRS reflect the ongoing use of technical HCH in Kerala. The calculated KSW in both rivers was very low in comparison with other Indian rivers. The average log K'OC for all the detected OCPs in both the rivers was lower than the predicted log KOC in equilibrium indicating the higher adherence of OCPs to sediment. Furthermore, fugacity fraction (fs/fw) was < 1.0 for all OCPs confirming the net deposition of OCPs into the sediment. Sediment concentrations for each of the OCPs in PRS and BRS did not surpass the threshold effect level and probable effect level as stipulated by the Canadian Council of Ministry of the Environment Guidelines. In addition, all the sites of both rivers had sediment quality guideline quotient (SQGQ) values below 0.1 indicating the absence of significant biological and ecological risks.

Investigation of organic contaminants in the blubber of a blue whale (Balaenoptera musculus) first stranded on the coast of Taiwan.

This study presents a comprehensive assessment of persistent organic pollutants (POPs) in the blubber of a stranded blue whale found on the coast of Taiwan. The analysis included polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), dichlorodiphenyltrichloroethane (DDT), Hexachlorobenzene (HCB), and polybrominated diphenyl ethers (PBDEs). The whale exhibited evident signs of emaciation, including low body weight, reduced blubber fat content, and thin blubber thickness. The dominant fatty acid type detected in the blubber was short-chain monounsaturated fatty acids (SC-MUFA), known to aid in thermoregulation. Stable isotope ratios indicated that the blue whale occupied a lower trophic position compared to a fin whale, suggesting its proximity to krill habitats in the Southern Ocean for feeding. The average concentrations of DDTs (1089.2 ± 4.7ng/g lw; ΣDDT) and PCBs (1057.1 ± 49.8ng/g lw) in the blubber were almost one order of magnitude higher than PAHs (41.7 ± 10.0ng/g lw), HCB (70.6 ± 2. ng/g lw), and PBDEs (7.2 ± 1.2ng/g lw). Pollutant concentrations in this individual blue whale were comparable to levels found in Norway, higher than those found in Chile, and notably lower than those found in Canada and Mexico. Calculating the biomagnification factor (BMF) for the POPs from krill (Euphausia superba) to the blue whale revealed significant bioaccumulation of pollutants in this particular whale. Additional research is imperative to achieve a thorough comprehension of bioaccumulation of POPs and their potential toxicological impacts on whale health.

Potential of Calabash (Lagenaria siceraria) and Sweet Potato (Solanum tuberosum) for the Remediation of Dichlorodiphenyltrichloroethane-Contaminated Soils in Tanzania

A study was conducted to test the potential of calabash, sweet potato, pumpkin, simsim and finger millet to phytoaccumulate dichlorodiphenyltrichloroethane (DDT) and its metabolites from NHC Morogoro- and PPO Tengeru-contaminated sites. Parallel field and screenhouse-potted soil experiments were performed to assess the efficacy with which the test plants phytoaccumulate DDT from the soil. In the screenhouse experiment, treatments were laid out following a split-plot arrangement in a completely randomized design (CRD), with the main plots comprising two DDT concentration levels–low (417 mg kg−1) or high (2308 mg kg−1)—and the plant species Cucurbita pepo, Lagenaria siceraria, Ipomoea batatus, Sesamum indicum and Eleusine coracana were considered as subplots. A field experiment with the same crop species as the treatments was laid out in a randomized complete block design, and both experiments were performed in triplicate. In addition to determining the concentration of persistent organic pesticides in the soil profile, parameters such as the total DDT uptake by plants, shoot weight and shoot height were monitored in both potted soil and open field experiments. Overall, calabash and sweet potato exhibited the highest (4.63 mg kg−1) and second highest (3.45 mg kg−1) DDT concentrations from the high residual DDT potted soil experiment. A similar trend was observed when the two plants were grown in low DDT soil. Sweet potato recorded the highest shoot height and weight in the potted soil experiments, indicating that increasing amounts of DDT had a minimal effect on the plant’s growth. Although sweet potato outperformed calabash in the amounts of DDT concentration in the shoots under open field experiments, the uptake of DDT by calabash was the second highest. Calabash—a wild non-edible plant in Tanzania—presents a potential phytoremediation alternative to edible and much studied pumpkin.

Adsorption Efficiency of Carbon Materials for the Removal of Organic Pollutants: DDT from Aqueous Solution.

Carbon nanotubes (CNTs) are widely used to adsorb organic pollutants from wastewater due to their porous structure, large specific surface area, and unique physical and chemical properties. Examining the interactions between pollutant molecules and carbon nanotubes is an important topic in the applications of nanotubes for the removal of pollutants. In this study, molecular dynamics (MD) and metadynamics simulations were used to investigate the adsorption mechanism of Dichlorodiphenyltrichloroethane (DDT) pollutants on carbon nanotubes. Obtained results revealed that functionalized CNTs (f-CNTs) with active groups exhibited significantly enhanced performance compared to pristine CNTs. The adsorption isotherms were analyzed at different DDT concentrations, and it was found that increasing the concentration of DDT molecules led to a decrease in system energy and increased stability. The presence of biosurfactants as functional groups on the CNTs enhanced the interaction between DDT molecules and the nanotubes. In CNT, the addition of DDT increases the van der Waals energy from -176.83 kJ/mol for 3 DDT molecules to -2237.88 kJ/mol for 50 DDT molecules. In the case of f-CNT, the van der Waals energy in the system with 50 DDT molecules is about 2061.05 kJ/mol more negative than the system with 3 DDT molecules. The number of contacts between the adsorbent and DDT molecules increased over time, indicating increased adsorption interaction. The radial distribution functions (RDF) of DDT molecules around CNTs and f-CNTs showed the highest probability of finding DDT molecules at a distance of about 0.5 nm from the adsorbent surface. The study provided valuable insights into the adsorption process and can guide future experimental studies.

Organochlorine Pesticides in Soil–Groundwater–Plant System in a Famous Agricultural Production Area in China: Spatial Distribution, Source Identification and Migration Prediction

Being a famous hometown of vegetables in China, Shouguang City has a long history of vegetable cultivation and is a comprehensive national commodity base for vegetables and fruits. In recent decades, with the expansion of agricultural production, the use of pesticides is increasing. Although organochlorine pesticides (OCPs) have been banned, there are still some residues in soil, groundwater and other media. The study on the migration of the OCPs in soil and groundwater is of great importance for the maintenance of food security. Using methods of hydrogeological survey, laboratory testing and numerical simulation, the spatial distribution characteristics, sources and pollution degree of OCPs in soil and groundwater were analyzed, and the migration and transformation of OCPs in soil–groundwater was dynamically simulated and predicted. The study showed that there were many kinds of OCPs residual in the soil environment. The hexachlorocyclohexane (HCHs) in the topsoil of the study area were mainly due to the use of lindane, and the main source of dichlorodiphenyltrichloroethane (DDTs) in soil was the use of DDTs in history. The contents of HCHs, DDTs and hexachlorobenzene in the topsoil of the study area were at a low level, while the content of endosulfan metabolite endosulfan sulfate was comparatively higher. In recent years, the content of organochlorine pesticides in soil has generally decreased. The indexes of OCPs in groundwater can meet the Standards for Drinking Water quality of China. It was predicted that the HCH pollutants would mainly be distributed in Gucheng Street, Shangkou Town, and its south area where the concentration exceeds 3 ng/L exceeds that of 240 km2. DDT pollutants would mainly be distributed in the east and north of Shouguang City, where the concentration beyond 0.6 ng/L exceeds that of 200 km2. Endosulfan sulfate pollutants would mainly be distributed in the Gucheng Street Office, Shangkou Town, and its south area where the concentration exceeds 1.5 ng/L will exceed that of 150 km2. Hexachlorobenzene (HCB) pollutants would mainly be distributed in Fengcheng in the west of Shouguang City and Nancha River in the northeast, where the concentration exceeds 0.2 ng/L will exceed that of 200 km2. The study enriched the monitoring data of OCPs in agricultural planting areas and provided reference for source analysis, migration prediction, and pollution prevention of OCPs.

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.

Feeding and biological differences induce wide variation in legacy persistent organic pollutant concentrations among toothed whales and polar bear in the Arctic

Polar bear and toothed whales in the Arctic exhibit orders of magnitude differences in concentrations of legacy persistent organic pollutants (POPs), which may be attributed to comparisons made across regions and different time frames. These interspecific differences could also be influenced by variations in biological susceptibility, including differences in xenobiotic biotransformation between polar bear, from the order Carnivora, and toothed whales, from the order Artiodactyla, as well as ecological factors, such as variation in feeding patterns. Here, we analyzed samples from subsistence-harvested toothed whales and polar bear in East Greenland collected between 2012 and 2021 and quantitatively compared interspecific differences in blubber/adipose polychlorinated biphenyl (PCB) and organochlorine (OC) pesticide concentrations. We further determined fatty acid (FA) signatures as dietary tracers to evaluate how feeding patterns influence POP concentrations relative to the influence of biological differences between taxa. Killer whale exhibited the highest mean concentrations of ΣPCBs (57.0 ± 14.0 mg/kg lw), Σdichlorodiphentlytrichloroethanes (ΣDDTs; 55.7 ± 13.1 lw), and Σchlordanes (ΣCHLs; 23.1 ± 5.6 mg/kg lw), while polar bear showed the second highest concentrations for ΣPCBs (12.5 ± 1.3 mg/kg lw), but comparable or even lower levels of all OCs relative to narwhal and pilot whale. Linear models using FA patterns as explanatory variables for POP concentrations demonstrated that, for ΣPCBs, diet differences explained most of the variation. Conversely, biological differences explained more of the variation for most OCs, especially for DDT, for which polar bear showed the lowest concentrations despite feeding on similarly high trophic position prey as killer whale. This novel quantitative comparison confirms that significant differences in legacy POP concentrations occur among Arctic marine mammal predators. Furthermore, the drivers of these differences are contaminant-specific, with feeding patterns primarily influencing PCB concentrations, taxa-specific biological characteristics (e.g., in xenobiotic biotransformation capacity) affecting DDT concentrations, and both factors contributing to variation in other OCs.

Polychlorinated biphenyls (PCBs) and organochlorine pesticides (OCPs) in water-sediment system of southern Mediterranean: Concentration, source and ecological risk assessment

Polychlorinated biphenyls (PCBs) and organochlorine pesticides (OCPs) were studied in the Nile Delta area of Egypt's southern Mediterranean for their environmental impacts, probable sources, and ecological risk assessment. Using the Gas Chromatography Triple Quadrupole technique, the residues of 16 OCPs and 18 PCBs were determined. The total OCPs content in the seawater and sediment samples ranged from 0.108 to 10.97 μg/L and 0.301 to 5.268 ng/g, respectively, while the PCBs residues had values between 0.808 and 1069.75 μg/L in seawater and between not detected and 575.50 ng/g in sediment samples. The findings of the risk evaluation showed that, except for endosulfan-I, OCPs caused little harm in seawater. However, PCB180, PCB153, PCB156, PCB126 and PCB138 posed a comparatively significant risk. The concentration of DDTs was higher than the effect range low and threshold effect level but remained below the effect range median and probable effect level, posing a minimal ecological concern.

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.