Global scale distribution, seasonal changes and long-range transport potentiality of endosulfan in the surface seawater and air

Toxic effects of commercial grade indoxacarb and endosulfan on Gammarus kischineffensis (Schellenberg, 1937) (Crustacea: Amphipoda)

This study was designed to investigate the toxic effects of two frequently used commercial insecticides containing endosulfan and indoxacarb on a freshwater amphipod Gammarus kischineffensis. In this context, the 24, 48, 72 and 96 h LC50 values of these pesticides were determined for G. kischineffensis. Then the histopathological effects of these pesticides on the gill tissues of this species were evaluated. At the end of the study, the 96 h LC50 values of commercial-grade endosulfan and indoxacarb for G. kischineffensis were determined as 1.861 μg L-1 and 20.212 mg L-1, respectively. Histopathologically, the most common histopathological alterations in individuals exposed to sublethal concentrations of commercial-grade endosulfan and indoxacarb were pillar cell hypertrophy resulting in atrophy of the hemocoelic space and hemocytic infiltration. Considering these results, it can be said that commercial-grade endosulfan is extremely and indoxacarb is slightly toxic to G. kischineffensis.

Distribution, sources, and eco-risk of Current-Use Pesticides (CUPs) in the coastal waters of the northern Shandong Peninsula, China

This study investigated the spatial distributions and seasonal variations of 19 CUPs in the coastal areas of the Shandong Peninsula and its surrounding rivers and assessed their ecological risk. In freshwater and seawater, insecticides (chlorpyrifos, methoxychlor, and pyridaben), as well as fungicides (fenarimol) and herbicides (dichlobenil) were the main pollutants (Detection Frequency: 100 %). Spatially, during winter, the regional pollution levels of Σ19CUPs in seawater showed a trend of Laizhou Bay (LZB, mean:4.13 ng L-1) > Yellow River Estuary (YRE, mean:2.57 ngL-1) > Bohai Bay (BHB, mean:2.21 ng L-1) > Yanwei Area (YWA, mean:1.94 ng L-1). The similarities of major substances between rivers and the marine environment suggest that river discharge is the main source of CUPs pollution in coastal areas. In summer, CUPs in rivers posed a high risk. In winter, the risk significantly decreased, indicating a moderate overall risk. Seawater exhibited a low risk in winter.

Atmospheric Hydroxyl Radical Reaction Rate Coefficient and Total Environmental Lifetime of α-Endosulfan

Endosulfan is a persistent organochlorine pesticide that was globally distributed before it was banned and continues to cycle in the Earth system. The chemical kinetics of the gas-phase reaction of α-endosulfan with the hydroxyl radical (OH) was studied by means of pulsed vacuum UV flash photolysis and time-resolved resonance fluorescence (FP-RF) as a function of temperature in the range of 348-395 K and led to a second-order rate coefficient kOH = 5.8 × 10-11 exp(-1960K/T) cm3 s-1 with an uncertainty range of 7 × 10-12 exp(-1210K/T) to 4 × 10-10 exp(-2710K/T) cm3 s-1. This corresponds to an estimated photochemical atmospheric half-life in the range of 3-12 months, which is much longer than previously assumed (days to weeks). Comparing the atmospheric concentrations observed after the global ban of endosulfan with environmental multimedia model predictions, we find that photochemical degradation in the atmosphere is slower than the model-estimated biodegradation in soil or water and that the latter limits the total environmental lifetime of endosulfan. We conclude that the lifetimes typically assumed for soil and aquatic systems are likely underestimated and should be revisited, in particular, for temperate and warm climates.

Spatiotemporal variations, surface inventory, and cross regional impact of current-use organoamine pesticides in Chinese Marginal Seas

Current-use Organoamine Pesticides (CUOAPs) are a growing concern as emerging pesticide pollutants that were initially discovered on a large scale in Chinese Marginal Seas (CMSs). The highest level was detected in the East China Sea in the late spring and decreased in the following order: East China Sea (early spring) > the South China Sea > the Bohai Sea. The crucial role played by the Yangtze and Yellow rivers as significant terrestrial sources were established. The fluctuations in the land application and riverine input led to variations in the source, distribution, and seasonal patterns of CUOAPs. Terrestrial-exported CUOAPs were transported and redistributed spatially by the surface ocean currents, resulting in significant regional disparities. The results displayed a pronounced terrestrial source signature and a cross-regional impact. By the ocean current transport, CMSs will likely become a secondary source region for the surrounding seas.

Ocean current redistributed the currently using Organoamine Pesticides in Arctic summer water

In a comprehensive study on the presence and distribution of Currently Using Organoamine Pesticides (CUOAPs) in the Arctic Ocean, this study collected and analyzed 36 surface seawater samples during the summer of 2021. The study detected 36 CUOAPs, 17 of these compounds at levels exceeding the Method Detection Limits (MDLs). Concentrations of CUOAPs ranged from 0.11 to 2.94 ng/L, exhibiting an average of 1.83 ± 0.83 ng/L. Spatial distribution analysis revealed lower CUOAP concentrations in the central Arctic Ocean, with Cycloate constituting the most abundant component (23.66 %). The investigation identified terrestrial inputs and long-range atmospheric transport as potential sources of CUOAPs in the Arctic Ocean region. The origins of individual CUOAPs appeared to be associated with application procedures and their propensity for co-occurrence at low latitudes. The study also examined the role of ocean currents in the transport and redistribution of CUOAPs in surface seawater across different regions. While ocean currents played a significant role, the influence of sea ice cover on CUOAP distribution was minimal. An ecological risk assessment analysis underscored the need for regional attention to the presence of CUOAPs in the Arctic Ocean.

Occurrence and ecological risk assessment of 16 phthalates in surface water of the mainstream of the Yangtze River, China

Phthalic acid esters (PAEs), a class of typical endocrine disruptors, have received considerable attention due to their widespread applications and adverse effects on biological health. In this study, 30 water samples, along the mainstream of the Yangtze River (YR), were collected from Chongqing (upper stream) to Shanghai (estuary) from May to June in 2019. The total concentrations of 16 targeted PAEs ranged from 0.437 to 20.5 μg/L, with an average of 1.93 μg/L, where dibutyl phthalate (DBP, 0.222-20.2 μg/L), bis (2-ethylhexyl) phthalate (DEHP, 0.254-7.03 μg/L), and diisobutyl phthalate (DIBP, 0.0645-0.621 μg/L) were the most abundant PAEs. According to the pollution level in the YR to assess the ecological risk posed by PAEs, the results showed medium risk level of PAEs in the YR, among which DBP and DEHP posed a high ecological risk to aquatic organisms. The optimal solution for DBP and DEHP is found in ten fitting curves. The PNEC_SSD of them is 2.50 μg/L and 0.34 μg/L, respectively.

Spatial distribution and risk assessment of conazole fungicides in surface seawater of the East China Sea

Conazole fungicides (CFs), the common-used pesticide in agriculture distributed widely in the environment. This research analyzed the occurrence, potential sources, and risks of eight CFs in the East China Sea surface seawater in the early summer of 2020. The total CF concentration ranged from 0.30 to 6.20 ng/L, with an average value of 1.64 ± 1.24 ng/L. Fenbuconazole, hexaconazole, and triadimenol were the major CFs that comprised >96 % of the total concentration. The Yangtze River was identified as the significant source of CFs from the coastal regions to the off-shore inputs. Ocean current was the first-order factor controlling the content and distribution of CFs in the East China Sea. Although risk assessment revealed CFs posed a low or no substantial risk to ecology and human health, long-term monitoring was also encouraged. This study provided a theoretical foundation for assessing CFs' pollution levels and potential risks in the East China Sea.

Distribution of organochlorine pesticides in surface and deep waters of the Southern Indian Ocean and coastal Antarctic waters

Antarctica is a remote and pristine region. Yet it plays a vital role in biogeochemical cycles of global anthropogenic contaminants, such as persistent organic pollution (POPs). This work reports the distribution of legacy and new POPs in surface and depth profiles/deeper water of the Southern Indian Ocean (SIO) and the coast of Antarctica (COA). Samples were collected during the 10th Indian Southern Ocean expedition (SOE-10) in the year 2017. Concentrations of ∑HCH (hexachlorocyclohexane), ∑DDT (dichlorodiphenyltrichloroethane), and ∑ENDO (endosulfan) in surface seawater from the SIO region ranged between not detected (ND) to 1.21 pg/Liter (pg L^-1) (average. ± s.d.: 0.35 ± 0.42 pg L^-1), ND to 1.83 pg L^-1 (0.69 ± 84 pg L^-1), and ND - to 2.06 pg L^-1 (0.56 ± 0., 88 pg L^-1), respectively. The concentrations of ∑HCH, ∑DDT, and ∑ENDO in COA ranged from ND to 0.98 pg L^-1 (0.25 ± 0.27 pg L^-1), ND to 3.61 pg L^-1(0.50 ± 1.08 pg L^-1), and ND to 2.09 pg L^-1 (0.45 ± 0.84 pg L^-1), respectively. Concentrations of isomers of endosulfan, and largely of HCHs, suggested an aged source. Some concentration ratios of α-to γ-HCH were close to 1, indicating a contribution from ongoing sources. Results indicate the important role of ocean currents in mediating the transport and detection of OCPs. As such, OCPs dynamics in deeper oceans may play an important role in OCPs cycling in the marine environment.

System biology analysis of endosulfan biodegradation in bacteria and its effect in other living systems: modeling and simulation studies

Endosulfan is a broadly applied cyclodiene insecticide which has been in use across 80 countries since last 5 decades. Owing to its recalcitrant nature, endosulfan residues have been reported from air, water and soil causing toxicity to various non-target organisms. Microbial decontamination of endosulfan has been reported previously by several authors. In the current study, we have evaluated the pathways of endosulfan degradation and its hazardous impact on other living beings including insects, humans, plants, aquatic life and environment by in-silico methods. For establishment of the endosulfan metabolism in different ecosystems, cell designer was employed. The established model was thereafter assessed and simulated to understand the biochemical and physiological metabolism of the endosulfan in various systems of the network. Topological investigation analysis of the endosulfan metabolism validated the presence of 207 nodes and 274 edges in the network. We have concluded that biomagnification of the endosulfan generally occurs in the various elements of the ecosystem. Dynamics study of endosulfan degrading enzymes suggested the important role of monooxygenase I, II and hydrolase in endosulfan bioremediation. Endosulfan shows toxicity in human beings, fishes and plants, however it is biodegraded by the microbes. To date, there are no reports of in- silico analysis of bioremediation of endosulfan and its hazardous effects on the environment. Thus, this report can be important in terms of modelling and simulation of biodegradation network of endosulfan and similar compounds and their impact on several other systems.Communicated by Ramaswamy H. Sarma.

Evolutionary Implications of Environmental Toxicant Exposure

Homo sapiens have been exposed to various toxins and harmful compounds that change according to various phases of human evolution. Population genetics studies showed that such exposures lead to adaptive genetic changes; while observing present exposures to different toxicants, the first molecular mechanism that confers plasticity is epigenetic remodeling and, in particular, DNA methylation variation, a molecular mechanism proposed for medium-term adaptation. A large amount of scientific literature from clinical and medical studies revealed the high impact of such exposure on human biology; thus, in this review, we examine and infer the impact that different environmental toxicants may have in shaping human evolution. We first describe how environmental toxicants shape natural human variation in terms of genetic and epigenetic diversity, and then we describe how DNA methylation may influence mutation rate and, thus, genetic variability. We describe the impact of these substances on biological fitness in terms of reproduction and survival, and in conclusion, we focus on their effect on brain evolution and physiology.

Bioaccumulation of organochlorine pesticide residues (OCPs) at different growth stages of pacific white leg shrimp (Penaeus vannamei): First report on ecotoxicological and human health risk assessment

Pesticide residues (PRs) in farmed shrimps are concerning food safety risks. Globally, India is a major exporter of pacific white leg shrimp (P. vannamei). This study was undertaken to analyze PRs in the water, sediments, shrimps, and feed at different growth stages to evaluate the ecotoxicological and human health risks. PRs in the seawater and sediments ranged from not detected (ND) to 0.027 μg/L and 0.006-12.39 μg/kg, and the concentrations were within the maximum residual limits (MRLs) and sediment quality guidelines prescribed by the World Health Organization and Canadian Environment Guidelines, respectively. PRs in shrimps at three growth stages viz. Postlarvae, juvenile, and adults, ranged from ND to 0.522 μg/kg, below the MRLs set by Codex Alimentarius Commission and European Commission. Most of the PRs in water, sediments, and shrimps did not vary significantly (p > 0.05) from days of culture (DOC-01) to DOC-90. The hazard quotient (HQ) and hazard ratio (HR) were found to be < 1, indicating that consumption of shrimps has no noncarcinogenic and carcinogenic risks. PRs in shrimp feed ranged from ND to 0.777 μg/kg and were found to be below the MRLs set by EC, which confirms that the feed fed is safe for aquaculture practices and does not biomagnify in animals. The risk quotient (RQ) and toxic unit (TU) ranged from insignificant level (ISL) to 0.509 and ISL to 0.022, indicating that PRs do not pose acute and chronic ecotoxicity to aquatic organisms. The study suggested no health risk due to PRs in shrimps cultured in India and exported to the USA, China, and Japan. However, regular monitoring of PRs is recommended to maintain a sustainable ecosystem.

Uptake of endosulfan isomers from soils by leafy vegetable lettuce: A comparative study between model-predicted and field-experimented results

The organochlorine insecticide endosulfan has been classified as a persistent organic pollutant due to its long persistence and high toxicity, and banned in most countries. However, endosulfan residues are still detected in various environmental sites (even in non-agricultural areas) and have a likelihood to return to agricultural soils through various routes. In this study, time-dependent uptake of α- and β-isomers of endosulfan by lettuce from soils was estimated using theoretical models which include parameters describing sorption/dissipation in soil and plants, plant transpiration, root-soil transfer, and plant growth. A chemical-specific residue (CSR) model developed in a previous study was used as a sub-model to estimate the portion of endosulfan residues in soils ready to be absorbed by lettuce, and the accuracy of the CSR model was verified by properly estimating concentrations of endosulfan isomers in soils with different organic matters; a low mean deviation (18.8 %) was observed between the modeled and measured values. Modeled results of β-endosulfan using a soil-lettuce uptake model satisfactorily matched the experimentally measured results, with a moderate correlation (R2 > 0.79) and a low residual error (0.42) against a mean factor of -1.04. However, the uptake model showed the low potential to predict the soil-lettuce uptake of α-endosulfan (176.3 % mean deviation), probably due to not considering an intrinsic trait of β-isomer converting to α-isomer. Although the improvement with more sophisticated parameters is needed, the plant uptake model developed in this study could be utilized to predict soil-lettuce uptake of at least β-endosulfan and as a model template that may apply for other types of plants and contaminants.

Assessment of organochlorine pesticides in the atmosphere of South Korea: spatial distribution, seasonal variation, and sources

Organochlorine pesticides (OCPs) are widely used in certain countries. We determined atmospheric concentrations, distribution patterns, and seasonal variations of OCPs at four sites in South Korea for 1 year. Samples of 22 OCPs were collected using a high-volume air sampler, and measured via the isotope dilution method with HRGC/HRMS. In South Korea, pentachlorobenzene (PeCB), hexachlorocyclohexane (HCB), and endosulfan (EnSF) were dominant, accounting for > 87% of total OCPs. Spatial distributions showed significant differences and the highest levels were observed in Seosan (295.2 pg·m^-3), indicating the compounding potential of diverse sources as Seosan has concentrated large-scale industrial complexes and agricultural activity (Seoul: 243.6 pg·m^-3 > Jeju: 193.5 pg·m^-3 > Baengnyeong: 178.2 pg·m^-3). The isomeric ratios of OCPs in the South Korean atmosphere indicated that the dominant sources of HCB and dichlorodiphenyltrichloroethane were primarily used in the past; meanwhile, chlordane (CHL) and EnSFs were derived from recent material inputs. Seasonally, OCP concentrations largely peaked in summer with minimum values in winter. This apparent temperature dependence suggests the re-volatilization of accumulated chemicals into the atmosphere. Additionally, an air mass back trajectory indicated the influence of pollutants released from a reservoir through long-range atmospheric transport in the summer. In particular, restricted OCPs are primarily released into the atmosphere by inadvertent sources, such as industrial activities and volatilization from contaminated areas. Thus, severe OCP pollution in Korea is due to the mobile nature of the particles. These data can be useful for the continuous monitoring of long-range transported air pollutants that are transferred between countries.

Applying the Global Monitoring Plan and analysis of POPs results in atmospheric air in Mexico (2017-2018)

Air is one of the target matrices of the Global Monitoring Plan (GMP) of the Stockholm Convention to determine concentrations and transport of Persistent Organic Pollutants (POPs). Mexico participates in the GMP for POPs in ambient air through the AIR-Global Environment Facility (GEF) program. The objective of this study was to analyze the results of POPs monitoring of air samples collected in Los Mochis, Sinaloa, Mexico, between 2017 and 2018. Passive samplers were used for the determination of chlorinated basic POPs, indicator polychlorinated biphenyls (Ind. PCBs), polybrominated biphenyl ethers (PBDEs), polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), and dioxin-like polychlorinated biphenyls (dl-PCBs). A principal component analysis was applied to determine relationships between pollutants and groups present in the ambient air of the rural study area. Of the total POPs analyzed, 85.56% were detected in ambient air samples from Mexico. Organochlorine compounds, as DDT derivatives, were identified mainly, as well as PBDEs, PCDDs, and PCDFs. The prevalence of compounds differed according to the seasonality of sampling, with no change in average concentration between monitoring years.

Occurrence, spatial distributions, and ecological risk of pyrethroids in coastal regions of South Yellow and East China Seas

Pyrethroids are increasingly receiving attention as aqueous micropollutants, but their presence has been reported only in a few small coastal areas. In this study, we investigated the distribution, sources, and risks of nine pyrethroids in large marine zones. The 40 seawater samples were collected from the South Yellow Sea (SYS) and East China Sea (ECS) in China, during the spring of 2020, using a high-volume, solid-phase extraction method. The total pyrethroid concentrations ranged from 0.72 to 1.82 ng L^-1 in the SYS and from 0.02 to 11.0 ng L^-1 in the ECS. We used cluster analysis to classify pollutant sources into five categories, and discussed the influence of sources on the transport and distribution of pyrethroids in each group. Ecological risk assessment indicated that pyrethroids pose a high risk to crustaceans and a negligible risk to others. These results are important for understanding the behavior of pyrethroids in marine environments.

Aberrant Hoxa10 gene methylation as a mechanism for endosulfan-induced implantation failures in rats

DNA methylation is a well-established epigenetic mechanism controlling gene expression. Environmental chemicals, such as pesticides have been shown to alter DNA methylation. We have previously shown that the insecticide endosulfan impairs female fertility in rats by increasing the rate of preimplantation embryo losses. In this study, we evaluated whether early postnatal exposure to endosulfan affects long-term transcriptional regulation of Homeobox A10 (Hoxa10) gene, which is a key marker of endometrial receptivity. Female rats were neonatally exposed to 6 or 600 μg/kg/day (ENDO6 and ENDO600, respectively) of endosulfan and uterine samples collected on gestational day (GD) 5. Hoxa10 protein and mRNA levels were assessed by immunohistochemistry and quantitative real-time PCR (qRT-PCR), respectively. In silico analysis of enzyme-specific restriction sites and predicted transcription factors were performed to investigate the methylation status of the regulatory regions of Hoxa10 gene by methylation-sensitive restriction enzymes-PCR technique. The expression of the DNA methyltransferases (Dnmts) was also evaluated. ENDO600 showed a decreased uterine Hoxa10 expression at protein and transcript level, while ENDO6 decreased only the level of transcripts, during the receptive stage. In addition, endosulfan increased levels of Dnmt3a and Dnmt3b. Dysregulation of DNA methylation patterns of Hoxa10 regulatory regions was detected in ENDO6- and ENDO600-treated rats. All these results suggest that aberrant DNA methylation in Hoxa10 gene could be an underlining mechanism contributing to explain endosulfan-induced preimplantation losses.

Biodegradation α-endosulfan and α-cypermethrin by Acinetobacter schindleri B7 isolated from the microflora of grasshopper (Poecilimon tauricola)

Extensive use of pesticides has led to the contamination of ecosystem. Therefore, it is important to isolate potential new pesticide-degrading bacteria. For the biodegradation of α-endosulfan and α-cypermethrin, a new bacterium was isolated from the body microflora of grasshopper (Poecilimon tauricola). Based on biochemical, morphological, and 16S rRNA sequence analysis, the isolated strain B7 was identified as Acinetobacter schindleri. This bacterial strain was screened for its α-cypermethrin and α-endosulfan degrading potential with minimal salt medium (MSM) and non-sulfur medium (NSM), respectively. When glucose was added to non-sulfur medium containing α-endosulfan (100 mg/L) and minimal salt medium containing α-cypermethrin (100 mg/L), both pesticide degradation and bacterial growth were increased. Acinetobacter schindleri B7 was able to degrade 67.31% of α-endosulfan and 68.4% of α-cypermethrin within 10 days. The degradation products of pesticides were determined by HPLC. As a result, A. schindleri, a Gram-negative bacterium, can inevitably be used in the biological treatment of environments exposed to pesticides.

Occurrence, distribution and risk assessment of organophosphate ester flame retardants and plasticizers in surface seawater of the West Pacific

Twenty-eight samples of surface seawater were collected from the West Pacific Ocean during 2019 using a high-volume solid-phase extraction with high-throughput organic analysis (Hi-throat/Hi-volume SPE) method, and concentrations of 10 organophosphate ester flame retardants and plasticizers (OPEs) were determined. The total OPE concentration in the samples was 3.02-48.4 ng L^-1 (mean 25.0 ± 10.5 ng L^-1), with tris(2-chloroethyl) phosphate (TCEP) being the largest contributor. Cluster analysis results showed off-shore input from the coast of East and Southeast Asia was an important source of these chemicals. Tri-p-tolyl phosphate (TpTP) should also be considered for long-term monitoring, because of its high detection frequency. Results of a risk assessment indicated low ecological risk to species in the West Pacific Ocean for TPhP and ΣOPEs. Hazard quotients (HQs) were all <1, indicating that the health risk to humans from these chemicals was at acceptable levels.

Distribution of eight organophosphorus pesticides and their oxides in surface water of the East China Sea based on high volume solid phase extraction method

In this study, we reported the occurrence of eight organophosphorus pesticides (OPPs) in the East China Sea. Forty samples were collected and analysed with a high volume solid phase extraction method (Hi-throat/Hi-volume SPE) in the early summer of 2020. All the target OPPs were detected in the surface water at one or more stations in the East China Sea, and the concentrations of ΣOPPs were in the range 0.0775-3.09 ng/L (mean: 0.862 ± 0.624 ng/L). Terbufos sulfone and fenthion were the main pollutants in this area, probably resulting from pesticide use in China and other countries. The off-shore input from coastal regions was suggested to be a major source of OPP pollution in the East China Sea, and the movement of ocean currents played an important role in their transportation because around 0.86 t OPPs passed through the Tsushima Strait from the East China Sea each month. An ecological risk assessment showed that these OPPs presented a high risk to species in the East China Sea, whereas they posed no health risk to humans under both the median and high exposure scenario.