Polychlorinated biphenyls and organochlorine pesticides in River Brahmaputra from the outer Himalayan Range and River Hooghly emptying into the Bay of Bengal: Occurrence, sources and ecotoxicological risk assessment

Genotoxic impact of agricultural insecticides as contaminants of river Teesta on the resident fish Pethia Conchonius

Fish, being highly sensitive to changes in the physico-chemical parameters of water, are good indicators of contamination. Teesta, a prominent northern West Bengal River system, is increasingly contaminated due to anthropogenic activities. This study aims to determine agricultural pesticide contamination and its genotoxic impact on the resident fish, Pethia conchonius, as an experimental organism. Sample water analysis from three riverine sites I, II & III, showed the presence of the insecticides imidacloprid (IMI), chlorpyrifos (CPF), bifenethrin (BF), cypermethrin (CP), difenthiuron, acetamiprid (AC) in the sites II and III only with adjoining agricultural lands. Comet assay revealed a significantly lower % Head DNA (~ 1.2 times), higher %Tail DNA (~ 16 times), and %Tail length (~ 3.1 times) in the gills of Pethia conchonius from sites II and III. About 4 and 10 times increase of micronuclei and other nuclear abnormalities were also noted in the erythrocytes of the fish from sites II and III than I, which was not contaminated. The antioxidant enzymes SOD, CAT, and GST activity and MDA levels were significantly higher (p < 0.05) in the liver samples from sites II and III, while AChE activity was significantly decreased (p < 0.001) in the brain tissues. Moreover, the sod, cat, and gpx expression in the hepatic cells were significantly upregulated compared to the β actin mRNA indicating increased oxidative stress. Increased genomic damage, antioxidant enzyme activity, higher MDA levels, decreased AChE activity in the brain, and the upregulation of hepatic genes strongly suggested the genotoxic effects of the detected insecticides in combination with other contaminants.

Impact of legacy and unintentionally produced polychlorinated biphenyls (PCBs) in effluents from two wastewater treatment plants in rivers near Barcelona, Spain

Polychlorinated biphenyls (PCBs) are a family of 209 congeners listed as Persistent Organic Pollutants in the Stockholm Convention. Although there has been a lot of focus on those congeners present in the Aroclor or Clophen technical mixtures commercialized in the past (legacy PCBs), other industrial processes such as paint and pigment production can generate other congeners as byproducts (Unintentionally Produced PCBs or UP-PCBs). The present study focuses on the analysis of 72 PCB congeners (including 42 UP-PCBs) in the two major rivers surrounding the city of Barcelona -Llobregat and Besós rivers-, and their levels in two wastewater treatment plants during the production of effluents and reclaimed water. It was observed that WWTP can efficiently remove PCBs from untreated water during sludge production where concentrations are six orders of magnitude higher than in water (in the ng g-1 and pg L-1 ranges, respectively). Although PCB levels in the effluent and reclaimed water replenishing the rivers are not negligible, these do not significantly increase the concentrations already found in the studied rivers, and in most cases PCB concentrations in river water are reduced after merging with the reclaimed water due to dilution effect. The presence of UP-PCB-11 (not present in the Aroclor technical mixtures) in the analyzed water and sludge samples is significant (ranging from 22 to 25 % of the total PCB amount in the Besós river), being often one of the most abundant PCB congeners.

Azoxystrobin induced genotoxicity in Pethia conchonius, a freshwater fish of river Teesta, India

Azoxystrobin, a widely used fungicide, can contaminate water bodies through surface run-off, posing a risk to aquatic organisms. This study aimed to assess the genotoxic effects of azoxystrobin on the fish Pethia conchonius. The 96 h lethal concentration (LC50) of azoxystrobin was determined to be 0.514 mg/L. Based on LC50, three sub-lethal concentrations (SLCs) of 0.025 mg/L, 0.0514 mg/L, and 0.103 mg/L were used to expose fish for 96 h. The blood and gill samples were collected at 24 h intervals for analysis. The Micronucleus (MN) and Comet assays were used to evaluate nuclear abnormalities and DNA damage, respectively. The results showed that the frequency of nuclear abnormalities and DNA damage in the exposed groups was significantly higher than the control, with increasing concentrations and duration of exposure. The highest levels of micronuclei, notched and blebbed nuclei, and DNA damage parameters were observed in the group exposed to SLC III for 96 h. These findings indicate that azoxystrobin is highly genotoxic to fish causing severe DNA damage.

Critical review on toxic contaminants in surface water ecosystem: sources, monitoring, and its impact on human health

Surface water pollution is a critical and urgent global issue that demands immediate attention. Surface water plays a crucial role in supporting and sustaining life on the earth, but unfortunately, till now, we have less understanding of its spatial and temporal dynamics of discharge and storage variations at a global level. The contamination of surface water arises from various sources, classified into point and non-point sources. Point sources are specific, identifiable origins of pollution that release pollutants directly into water bodies through pipes or channels, allowing for easier identification and management, e.g., industrial discharges, sewage treatment plants, and landfills. However, non-point sources originate from widespread activities across expansive areas and present challenges due to its diffuse nature and multiple pathways of contamination, e.g., agricultural runoff, urban storm water runoff, and atmospheric deposition. Excessive accumulation of heavy metals, persistent organic pollutants, pesticides, chlorination by-products, pharmaceutical products in surface water through different pathways threatens food quality and safety. As a result, there is an urgent need for developing and designing new tools for identifying and quantifying various environmental contaminants. In this context, chemical and biological sensors emerge as fascinating devices well-suited for various environmental applications. Numerous chemical and biological sensors, encompassing electrochemical, magnetic, microfluidic, and biosensors, have recently been invented by hydrological scientists for the detection of water pollutants. Furthermore, surface water contaminants are monitored through different sensors, proving their harmful effects on human health.

Polychlorinated biphenyls in the surface and deep waters of the Southern Indian Ocean and Coastal Antarctica

Polychlorinated biphenyl compounds (PCBs) are industrial chemicals whose production was discontinued in the early nineties in most countries. Sill, PCBs are detectable in pristine and remote locations. Occurrence in regions such as Southern Oceans and Antarctica are influenced by the global, and regional, cycling. Here, we studied the surface and deep ocean distribution of indicator- and dioxin-like PCB congeners in the Southern Indian Ocean (SIO), and the coast of Antarctica (COA) during the tenth Indian Southern Ocean Expedition (SOE-10), December 2017-February 2018. ∑21PCBs in SIO surface waters ranged from 3.8 to 167.1 pg L-1 (average ± standard deviation: 35.7 ± 48.4 pg L-1), and in COA from 1.0 to 41.8 pg L-1 (13.8 ± 12.7 pg L-1), respectively. A noticeable gradient was observed, with higher PCBs levels in northern latitudes than southern latitudes in the SIO, and higher levels in the eastern longitudes compared to western longitudes in the COA. Results suggest the influence of secondary sources, or re-emission, of PCBs in the Southern Oceans and Antarctica. Both regions showed notable PCB levels in surface and deep waters (up to 1000 m) due to ongoing surface sources and remineralization processes in deeper waters. Multimedia modeling with the global model (BETR-Global) suggests the SIO act as a net sink for PCBs in the ocean.

Impact of total phenolic compounds on ecological and health risks of water and sediments from Timsah Lake, Suez Canal, Egypt

This study aimed to measure spatial and temporal distributions of total phenolic compounds and their ecological and health hazards using UV-vis spectrophotometers as a low-cost, fast, simple method in water and sediments collected from Timsah Lake, Suez Canal, Egypt, 2022. Also, assessing highly adaptive fungal species associated with contamination is designed. Due to human and environmental activities and industrial waste discharges, Timsah Lake is increasingly threatened by all kinds of pollutants. The results indicated that the seasonal concentration means of the phenolic compounds were winter (0.229) > spring (0.161) > summer (0.124) > autumn (0.131) mg/l and winter (3.08) > summer (2.66) mg/g in water and sediment samples, respectively. The result has shown that the phenol concentrations in all stations were more than 0.005 and 0.1 mg/l for Egyptian National Standards and World Health Organization (WHO) for drinking water but less than the limits of 1 mg/l for wastewater. Notably, the fungi recorded the highest counts during spring, totaling 397 colonies/100 ml of water and 842 colonies/gram of sediment. Four isolates of fungi were identified and deposited in the GenBank database by Aspergillus terreus, Aspergillus terreus, Penicillium roqueforti, and Penicillium rubens under accession numbers OR401933, OR402837, OR402878, and OR424729, respectively. Moreover, ecological risk (RQ) for the total phenolic compounds was > 1 in all investigated stations for water and sediments. The hazard quotient is HQ < 1 in all seasons in water and sediments except winter. The hazard index (HI) in water and sediments for children is higher than for adults. It can be concluded that the low-cost, fast, simple method for determining phenolic content in water and sediment samples, using UV-vis spectrophotometry, was useful for predicting the reactivates of a wide variety of phenol and their derivatives. Furthermore, it can be concluded that Periodic assessments of water quality and strict regulations are necessary to safeguard this vital resource from pollution and ensure the well-being of future generations. Finally, policymakers and water treatment specialists might use the information from this research to reduce these chemical pollutants in Egypt.

Assessment of imidacloprid induced genotoxicity in Pethia conchonius (Rosy barb), a common freshwater fish of India

Imidacloprid is one of the highly efficient, globally used neonicotinoid groups of insecticides. The indiscriminate use of imidacloprid is contaminating large water bodies affecting not only the target organisms but also non-target organisms including fish. The present study aimed to assess the extent of nuclear DNA damage by imidacloprid in Pethia conchonius a freshwater fish in India using comet and micronucleus assays. The LC50 value of imidacloprid was estimated to be 227.33 mg L-1. Based on the LC50-96 h value, three sub-lethal concentrations of imidacloprid, SLC I -18.94 mg L-1, SLC II -28.41 mg L-1 and SLC III -56.83 mg L-1 were used to detect its genotoxic effect at DNA and cellular level. The imidacloprid exposed fishes exhibited higher DNA damage and nuclear abnormalities (p < 0.05) than the control. The %head DNA, %tail DNA, tail length and the frequency of micronuclei with other nuclear abnormalities like blebbed and notched nuclei were significantly higher than the control in a time and concentration-dependent manner. The DNA damage parameters such as %head DNA (29.107 ± 1.843), %tail DNA (70.893 ± 1.843), tail length (361.431 ± 8.455) micronucleus (1.300 ± 0.019), notched (0.844 ± 0.011) and blebbed (0.811 ± 0.011) nuclei were found to be highest for SLC III (56.83 mg L-1) at 96 h. The findings indicate that IMI is highly genotoxic in fish and other vertebrates leading to mutagenic/clastogenic effects. The study will be helpful in optimization of the imidacloprid use.

Bioanalytical and chemical characterization of organic micropollutant mixtures in long-term exposed passive samplers from the Joint Danube Survey 4: Setting a baseline for water quality monitoring

Monitoring methodologies reflecting the long-term quality and contamination of surface waters are needed to obtain a representative picture of pollution and identify risk drivers. This study sets a baseline for characterizing chemical pollution in the Danube River using an innovative approach, combining continuous three-months use of passive sampling technology with comprehensive chemical (747 chemicals) and bioanalytical (seven in vitro bioassays) assessment during the Joint Danube Survey (JDS4). This is one of the world's largest investigative surface-water monitoring efforts in the longest river in the European Union, which water after riverbank filtration is broadly used for drinking water production. Two types of passive samplers, silicone rubber (SR) sheets for hydrophobic compounds and AttractSPETM HLB disks for hydrophilic compounds, were deployed at nine sites for approximately 100 days. The Danube River pollution was dominated by industrial compounds in SR samplers and by industrial compounds together with pharmaceuticals and personal care products in HLB samplers. Comparison of the Estimated Environmental Concentrations with Predicted No-Effect Concentrations revealed that at the studied sites, at least one (SR) and 4-7 (HLB) compound(s) exceeded the risk quotient of 1. We also detected AhR-mediated activity, oxidative stress response, peroxisome proliferator-activated receptor gamma-mediated activity, estrogenic, androgenic, and anti-androgenic activities using in vitro bioassays. A significant portion of the AhR-mediated and estrogenic activities could be explained by detected analytes at several sites, while for the other bioassays and other sites, much of the activity remained unexplained. The effect-based trigger values for estrogenic and anti-androgenic activities were exceeded at some sites. The identified drivers of mixture in vitro effects deserve further attention in ecotoxicological and environmental pollution research. This novel approach using long-term passive sampling provides a representative benchmark of pollution and effect potentials of chemical mixtures for future water quality monitoring of the Danube River and other large water bodies.

Pollution and risk assessment of phenolic compounds in drinking water sources from South-Western Nigeria

This study reports the occurrence and risk assessment of 2,4-dinitrophenol (2,4-DNP), phenol (PHE), and 2,4,6-trichlorophenol (2,4,6-TCP) in drinking water sources in three south-western States in Nigeria (Osun, Oyo, and Lagos). Groundwater (GW) and surface water (SW) were collected during dry and rainy seasons of a year. The detection frequency of the phenolic compounds followed the trend Phenol > 2,4-DNP > 2,4,6-TCP. The mean concentrations of 2,4-DNP, Phenol, and 2,4,6-TCP in GW/SW samples from Osun State were 639/553 μg L-1, 261/262 μg L-1, and 169/131 μg L-1 during the rainy season and 154/7 μg L-1, 78/37 μg L-1, and 123/15 μg L-1 during the dry season, respectively. In Oyo State, the mean concentrations were 165/391 μg L-1 for 2,4-DNP and 71/231 μg L-1 for Phenol in GW/SW samples, respectively, during the rainy season. Generally, in the dry season, these values decreased. In any case, these concentrations are higher than those previously reported in water from other countries. The concentration of 2,4-DNP in water posed serious ecological risks to Daphnia on the acute scale while it was algae on the chronic scale. Estimated daily intake and hazard quotient calculations suggest that 2,4-DNP and 2,4,6-TCP in water pose serious toxicity concerns to humans. Additionally, the concentration of 2,4,6-TCP in water from Osun State in both seasons of the year and in both groundwater and surface water poses significant carcinogenic risks to persons ingesting water from these sources in the State. Every exposure group studied were at risk from ingesting these phenolic compounds in water. However, this risk decreased with increasing age of the exposure group. Results from the principal component analysis indicate that 2,4-DNP in water samples is from an anthropogenic source different from that for Phenol and 2,4,6-TCP. There is a strong need to treat water from GW and SW systems in these States before ingesting while assessing their quality regularly.

Sediment-water partitioning and risk assessment of organochlorine pesticides along the urban, peri-urban and rural transects of Krishna River Basin, Peninsular India

Organochlorine pesticides (OCPs) were widely used in the past for pest control in agricultural lands and vector control programs in India. Due to their persistence and toxic impacts, we have quantified twenty OCPs in surface water, groundwater, and surface sediment samples along the Krishna River Basin (KRB), flowing through Peninsular India. Samples were collected along the urban, peri-urban, and rural transects of the KRB to understand the relation between the occurrence of pesticidal organochlorine pollutants based on the land use and land cover (LULC) and asses potential risk. Diagnostic ratios revealed ongoing Lindane usage in rural and peri-urban transects. On the contrary, the urban transect of the Musi River (MR) showed fresh inputs of technical HCH. The ratios of (p,p'-DDE+ p,p'-DDD)/ΣDDT >0.5 and α/β-Endosulfan < 2.33 for most of the sites across the three transects for surface water, groundwater, and sediment indicate past DDT and Endosulfan usage across KRB. Excluding p,p'-DDE, and heptachlor in most of the sites, the logK_OC' was higher than logK_OC for other OCPs in the urban transect. However, for all the OCPs, the logK_OC' was lower than logK_OC in the peri-urban and rural transects of KRB thereby indicating that riverine sediment is acting as a sink for OCPs. The Krishna River annually transport about 0.24 tons HCH, 0.11 tons of DDT and 0.1 tons of Endosulfan. Despite having low water discharge, the compound-specific fluxes of the Wyra river are higher than the other two tributaries. Ecotoxicological risk assessment based on the Hazard Quotient suggested DDT pose higher risks to scud (zooplankton) and dinoflagellate and diatom (phytoplankton) whereas Endosulfan poses a threat to Bluegill (fish).

Ecological and human health hazards; integrated risk assessment of organochlorine pesticides (OCPs) from the Chenab River, Pakistan

Carcinogenic hazards to human health were investigated through oral and dermal exposure to organochlorine pesticides (OCPs) from water samples (n = 120) of River Chenab, Pakistan. The Pioneering study aimed to employ an integrated geographic information system (GIS) based geostatistical method for the determination of pollution load by GC-ECD from water of River Chenab. The residual levels of OCPs detected from water samples ranged from 0.54 to 122 ng L^-1 with significant prevalence of DDE and α-HCH. Results of the Nemerrow pollution index (NeI), single pollution index (SPI), and comprehensive pollution index (CPI) reflected the downstream zone a stern pollution risk zone. The spatial distribution pattern through geostatistical approaches also revealed significantly higher (p < 0.05) OCP levels in the downstream zone. Risk quotient (RQ_CCC) of surface water quality with respect to heptachlor epitomized a high level of risk (RQ_CCC > 1). Non-carcinogenic human health risk (Σ HQ) assessment ranged from 8.39 × 10^-9 to 1.7 × 10^-3, which represented a marginal risk through oral and dermal exposure. However, carcinogenic risks by oral exposure route were ranged from 3.57 × 10^-11 to 4.46 × 10^-6. Estimated cancer risk (ΣCR) exhibited a considerable carcinogenic risk posed by heptachlor, α-HCH and dieldrin. It is suggested to employ an immediate mitigation strategy for the constant discharge of OCPs in the studied area.

Polybrominated diphenyl ethers in water, suspended particulate matter, and sediment of reservoirs and their tributaries in Shenzhen, a mega city in South China

Urban reservoirs serve many purposes including recreation and drinking water, and larger bodies of water can alter the surrounding air temperatures, making urban areas cooler in summer and warmer in winter. However, reservoirs may also be sinks for contaminants. One such group of contaminants, the polybrominated diphenyl ethers (PBDEs), are persistent organic pollutants known to accumulate in sediments and suspended particulate matter (SPM). Few studies have been conducted on PBDEs in water, SPM, and sediment from reservoirs of Shenzhen which is a mega city in South China. To this end, 12 PBDEs were measured in water, SPM, and sediment samples during the dry season (DS) and wet season (WS), to explain the spatiotemporal distribution, congener profiles, sources, and risks of pollutants in four reservoirs (A-D) and their tributaries in the study region. The concentration of ∑₁₂PBDEs during the DS was found to be significantly higher than that during the WS. Source apportionment suggested that commercial penta-, octa-, and deca-BDEs are the major components of PBDEs, resulting mainly from atmospheric deposition, wastewater discharge, and external water-diversion projects. Further, attention should be paid to electronic equipment manufacturing factories in the study area. Risk assessment indicated risk of PBDEs (especially BDE-209) in sediment and SPM to be of concern. This study provides important data support for the control of PBDEs in natural drinking water sources.

A holistic review on trend, occurrence, factors affecting pesticide concentration, and ecological risk assessment

Demographic outbursts and increased food demands invoke excessive use of pesticides in the agricultural field for increasing productivity which leads to the relentless decline of riverine health and its tributaries. These tributaries are connected to a plethora of point and non-point sources that transport pollutants including pesticides into the Ganga river's mainstream. Simultaneous climate change and lack of rainfall significantly increase pesticide concentration in the soil and water matrix of the river basin. This paper is intended to review the paradigm shift of pesticide pollution in the last few decades in the river Ganga and its tributaries. Along with this, a comprehensive review suggests the ecological risk assessment method which facilitates policy development, sustainable riverine ecosystem management, and decision-making. Before 2011, the total mixture of Hexachlorocyclohexane was found at 0.004-0.026 ng/mL in Hooghly, but now, the concentration has increased up to 0.465-4.132 ng/mL. Aftermath of critical review, we observed maximum residual commodities and pesticide contamination reported in Uttar Pradesh > West Bengal > Bihar > Uttara Khand possibly because of agricultural load, increasing settlement, and incompetency of sewage treatment plant in the reclamation of pesticide contamination.

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.

Risk assessment of persistent pesticide pollution: Development of an indicator integrating site-specific characteristics

Detection of high pesticide concentrations in sediments and water often leads to prioritizing a site as being 'at risk'. However, the risk does not depend on pesticide concentration alone, but on other site-specific characteristics also. We developed an indicator that identifies the 'Level of Concern' by integrating five such characteristics: (i) pesticide concentrations in surface and groundwater causing risks to ecological health (ii) impacts on human health, (iii) water scarcity, (iv) agricultural production, and (v) biodiversity richness. We applied this framework in an agricultural region of the Lower Ganges Basin in West Bengal, India. We measured concentrations of selected organochlorine pesticides (OCPs) in surface and groundwater within an 8 km² area in 2019. Of 20 banned and restricted OCPs, 11 were detected as causing high risk to ecological health and 10 at concentrations above the Accepted Carcinogenic Risk Limit (ACRL) for humans. In the pre-monsoon, the mean concentrations of ΣOCPs in groundwater and surface water were 126.9 ng/L and 104 ng/L, in the monsoon they were 144.7 ng/L and 138 ng/L, and in the post-monsoon 122.1 ng/L and 147 ng/L respectively. In groundwater, no significant seasonal difference was observed in most pesticides. In the surface water, 7 pesticides were significantly higher in the monsoon and post-monsoon, which may be attributed to increased runoff as well as post monsoon application of OCPs. In September 2022 we again measured OCP concentrations in surface water and sediment. The mean concentration of 14 of the 20 measured OCPs were found to be significantly lower in the post-pandemic period compared to the pre-pandemic time. These lower pesticide concentrations may indicate a reduced use of OCPs in agricultural practices during the pandemic. This area was identified as being at the highest Level of Concern, even though the OCP concentrations alone conformed to general guidelines.

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.

Toxicity of polychlorinated biphenyls in aquatic environments - A review

The assessment of polychlorinated biphenyls (PCBs) and their congeners resulting from the pollution of all environmental media is inherently related to its persistence and ubiquitous nature. In principle, determination of this class of contaminants are limited to the determination of their concentrations in the various environmental matrices. For solving many problems in this context, knowledge of the emission sources of PCBs, transport pathways, and sites of contamination and biomagnification is of great benefit to scientists and researchers, as well as many regulatory organizations. By far the largest amounts of PCBs, regardless of their discharged points, end up in the soil, sediment and finally in different aquatic environments. By reviewing relevant published materials, the source of origin of PCBs in the environment particularly from different pollution point sources, it is possible to obtain useful information on the nature of different materials that are sources of PCBs, or their concentrations and their toxicity or health effects and how they can be removed from contaminated media. This review focuses on the sources of PCBs in aquatic environments and critically reviews the toxicity of PCBs in aquatic animals and plants. The review also assesses the toxicity equivalency factors (TEFs) of PCBs providing valuable knowledge to other scientists and researchers that enables regulatory laws to be formulated based on selective determination of concentrations regarding their maximum permissible limits (MPLs) allowed. This review also supplies a pool of valuable information useful for designing decontamination technologies for PCBs in media like soil, sediment, and wastewaters.

Contamination, spatial distribution, and source contribution of persistent organic pollutants in the soil of Guiyang city, China: a case study

The contamination of persistent organic pollutants (POPs), including dichlorodiphenyltrichloroethane (DDT), hexachlorocyclohexane (HCH), and polycyclic aromatic hydrocarbon (PAH), is the most studied environmental issue. In 2020, a total of sixty soil samples collected from ten locations in Guiyang were analyzed to assess the presence of four DDTs and HCHs and sixteen PAHs. The concentrations of total DDTs, total HCHs and Σ₁₆PAHs in the soil were between 0.26 and 12.76, 0.23 and 51.80 μg/kg, and 10.02 and 1708.86 μg/kg, respectively. The mean and median concentrations of total DDTs, total HCHs and Σ₁₆PAHs in the soil were 1.04 and 0.26 μg/kg, 4.32 and 0.23 μg/kg, 139.14 and 98.98 μg/kg, respectively. p,p'-DDT, p,p'-DDD and γ-HCH the dominant organochloride pollutants in the soil, while 4-ring PAHs were the dominant PAHs, occupying 41.1-53.6% of the total PAHs in the soil. The highest levels of PAHs in the soil were observed in areas of Guiyang with relatively larger population densities and more developed heave industries. Various diagnostic tools were used to identify the potential sources of the POPs in the soil. The data indicated that DDTs and HCHs were from past and recent common inputs and that mixtures of several combustion activities (biomass, coal and petroleum combustion, diesel, gasoline, and vehicular emissions) were the major sources of PAHs in the Guiyang soil. The results provide information for the assessment of the extent of POP pollution in the Guiyang soil and can help authorities establish environmental protection regulations and soil remediation techniques.

The strategy for estrogen receptor mediated-risk assessment in environmental water: A combination of species sensitivity distributions and in silico approaches

Risk assessment for molecular toxicity endpoints of environmental matrices may be a pressing issue. Here, we combined chemical analysis with species sensitivity distributions (SSD) and in silico docking for multi-species estrogen receptor mediated-risk assessment in water from Dongjiang River, China. The water contains high levels of phenolic endocrine-disrupting chemicals (PEDCs) and phthalic acid esters (PAEs). The concentration of ∑₄PEDCs and ∑₆PAEs ranged from 2202 to 3404 ng/L and 834-4368 ng/L, with an average of 3241 and 2215 ng/L, respectively. The SSD approach showed that 4-NP, BPA, E2 of PEDCs, and DBP, DOP, and DEHP could severely threaten the aquatic ecosystems, while most other target compounds posed low-to-medium risks. Moreover, binding affinities from molecular docking among PEDCs, PAEs, and estrogen receptors (ERα, Erβ, and GPER) were applied as toxic equivalency factors. Estrogen receptor-mediated risk suggested that PEDCs were the main contributors, containing 53.37-69.79% of total risk. They potentially pose more severe estrogen-receptor toxicity to zebrafish, turtles, and frogs. ERβ was the major contributor, followed by ERα and GPER. This study is the first attempt to assess the estrogen receptor-mediated risk of river water in multiple aquatic organisms. The in silico simulation approach could complement toxic effect evaluations in molecular endpoints.

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.

Organochlorine pesticides and polychlorinated biphenyls in high mountain lakes, Mexico

Pollution levels of organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs) were investigated in the El Sol and the La Luna alpine lakes. The lakes are located in central Mexico, in the crater of the Nevado de Toluca volcano. The El Sol and the La Luna lakes are extremely relevant in Mexico and in the world because they are recognized as pristine regions and environmental reservoirs. Samples of atmospheric aerosol, sediment, plankton, and Tubifex tubifex (sludge worm) were collected at three different sample locations for three years (2017, 2018, and 2019) at three different times of year, meaning that the weather conditions at the time of sampling were different. Pollutants were analysed by gas chromatography-mass spectrometry with negative chemical ionisation (GC-MS/NCI). Endosulfan was the most frequent and abundant pollutant, showing the highest peaks of all. Atmospheric aerosol revealed Σ₂ = 45 pg/m³, including α and β, while sediment lakes displayed α, β and endosulfan sulfate as Σ₃ = 1963 pg/g, whereas plankton and Tubifex tubifex showed Σ₂ = 576 pg/g and 540 pg/g for α and β respectively. Results of endosulfan ratios (α/β) and (α-β/endosulfan sulfate) suggest that both fresh and old discharges continue to arrive at the lakes. This study shows for the first time the pollution levels of OCP and PCB in high mountain lakes in Mexico. These results that must be considered by policy makers to mitigate their use in the various productive activities of the region.

Unregulated discharge of wastewater in the Mahanadi River Basin: Risk evaluation due to occurrence of polycyclic aromatic hydrocarbon in surface water and sediments

Exposure to polycyclic aromatic hydrocarbons (PAHs) through contaminated water may adversely affect human health and ecology. Water and sediment samples collected from the Mahanadi River Basin (MRB) were analyzed for the presence of sixteen priority PAHs. Results showed that the concentrations of Σ16 PAHs in water and sediments ranged from 13.1 to 685.4 μg/L and 302.6 to 728.2 ng/g. In river water samples, the highest mean concentrations were recorded for Acenaphthylene (18.73 ± 11.61 μg/L) and Benzo(a)Anthracene (10.11 ± 8 μg/L). On the contrary, the maximum concentration was recorded for Phenanthrene (96.18 ± 50.66 ng/g) and Pyrene (76.69 ± 22.73 ng/g) in sediment samples. Human health risk assessment suggests low risk, with incremental lifetime cancer risk (ILCR) being 37.44 × 10^-5 for children and 21.82 × 10^-5 for adults. In contrast, ecological risk assessment showed a high toxic equivalent quotient of 40.68 ng/g and mutagenic equivalent quotient of 39.74 ng/g suggesting elevated adverse risk to aquatic species.

Ecological and AhR-mediated risk assessment of polycyclic aromatic hydrocarbons and polybrominated diphenyl ethers on multiple aquatic species in river water: A combined chemical analysis and in silico approach

Assessing the adverse health risks at molecular endpoints to various aquatic organisms could be an urgent issue. In this manuscript, the ecological and AhR-mediated risk of sixteen polycyclic aromatic hydrocarbons (PAHs) and six polybrominated diphenyl ethers (PBDEs) in surface water of Dongjiang River, Southern China was evaluated using chemical analysis and in silico approaches. Average concentrations of ∑₁₆PAHs and ∑₆PBDEs were 586.3 ng/L and 2.672 ng/L in the dry season (DS), and 366.8 ng/L and 2.554 ng/L in the wet season (WS). Concentrations of PAHs during the DS were significantly higher than that in the WS, while no obvious seasonal distribution was observed for PBDEs. Only Ant and BaP in all congers of PAHs posed low to medium ecological risks, and PBDEs posed a low ecological risk. Moreover, AhR-mediated risk from PAHs was two orders of magnitude higher that from PBDEs, and the AhR-mediated toxicity on frog and eel were higher than those on other aquatic organisms in Dongjiang River. Phe and BDE209 were the significant contributor to the AhR-mediated risk induced by PAHs and PBDEs, respectively. This study is the first attempt to assess AhR-mediated risk of river water in multiple aquatic organisms.

Low-dose PCB126 exposure disrupts cardiac metabolism and causes hypertrophy and fibrosis in mice

The residue of polychlorinated biphenyls (PCBs) exists throughout the environment and humans are subject to long-term exposure. As such, the potential environmental and health risk caused by low-dose exposure to PCBs has attracted much attention. 3, 3', 4, 4', 5-pentachlorobiphenyl (PCB126), the highest toxicity compound among dioxin-like-PCBs, has been widely used and mass-produced. Cardiotoxicity is PCB126's crucial adverse effect. Maintaining proper metabolism underlies heart health, whereas the impact of PCB126 exposure on cardiac metabolic patterns has yet to be elucidated. In this study, we administered 0.5 and 50 μg/kg bw of PCB126 to adult male mice weekly by gavage for eight weeks. Pathological results showed that low-dose PCB126 exposure induced heart injury. Metabolomic analysis of the heart tissue exposed to low-dose PCB126 identified 59 differential metabolites that were involved in lipid metabolism, amino acid metabolism, and the tricarboxylic acid (TCA) cycle. Typical metabolomic characteristic of cardiac hypertrophy was reflected by accumulation of fatty acids (e.g. palmitic, palmitoleic, and linoleic acid), and disturbance of carbohydrates including D-glucose and intermediates in TCA cycle (fumaric, succinic, and citric acid). Low-dose PCB126 exposure increased glycine and threonine, the amino acids necessary for the productions of collagen and elastin. Besides, PCB126-exposed mice exhibited upregulation of collagen synthesis enzymes and extracellular matrix proteins, indicative of cardiac fibrosis. Moreover, the expression of genes related to TGFβ/PPARγ/MMP-2 signaling pathway was perturbed in the PCB126-treated hearts. Together, our results reveal that low-dose PCB126 exposure disrupts cardiac metabolism correlated with hypertrophy and fibrosis. This study sheds light on the underlying mechanism of PCBs' cardiotoxicity and identifies potential sensitive biomarkers for environmental monitoring.

The concentration of persistent organic pollutants in water resources: A global systematic review, meta-analysis and probabilistic risk assessment

The persistent organic pollutants (POPs) are environmentally stable and highly toxic chemicals that accumulate in living adipose tissue and have a very destructive effect on aquatic ecosystems. To analyze the evolution of the concentration and prevalence of POPs such as α-HCH, β-HCH, γ-HCH, ∑-HCH, Heptachlor, Aldrin, p,p'-DDE, p,p'-DDT, ∑-DDT, and ∑-OCP in water resources, a search between January 01, 1970, to February 10, 2020, was followed using a systematic review and meta-analysis prevalence. Among the 2306 explored articles in the reconnaissance step, 311 articles with 5315 exemplars, 56 countries, and 4 types of water were included in the meta-analysis study. Among all studied POPs, the concentration of p,p'-DDT in water resources was the highest, especially in drinking water resources. The overall rank order based on the concentration and prevalence of POPs were surface water > drinking water > seawater > groundwater. To identify POPs-contaminated areas, the distance from the mean relative to their distribution was considered. The most to the least polluted areas included: South Africa, India, Turkey, Pakistan, Canada, Hong Kong, and China. The highest carcinogenic risk was observed for β-HCH (Turkey and China), followed by α-HCH (Mexico). The highest non-carcinogenic risk was identified for Aldrin (all analyzed countries), followed by Dieldrin (Turkey) and γ-HCH (Mexico). The Monte Carlo analysis (under the assumption that γ-HCH has a normal distribution), the mean obtained was 8.22E-07 for children and 3.83E-07 for adults. This is in accordance with the standard risk assessment approach. In terms of percentiles, the Monte-Carlo approach indicates that 75% of child population is under the 1.07E-06 risk and 95% of adults under 7.35E-06.

A Review on Emerging Pollutants in the Water Environment: Existences, Health Effects and Treatment Processes

Emerging pollutants (EPs), also known as micropollutants, have been a major issue for the global population in recent years as a result of the potential threats they bring to the environment and human health. Pharmaceuticals and personal care products (PPCPs), antibiotics, and hormones that are used in great demand for health and cosmetic purposes have rapidly culminated in the emergence of environmental pollutants. EPs impact the environment in a variety of ways. EPs originate from animal or human sources, either directly discharged into waterbodies or slowly leached via soils. As a result, water quality will deteriorate, drinking water sources will be contaminated, and health issues will arise. Since drinking water treatment plants rely on water resources, the prevalence of this contamination in aquatic environments, particularly surface water, is a severe problem. The review looks into several related issues on EPs in water environment, including methods in removing EPs. Despite its benefits and downsides, the EPs treatment processes comprise several approaches such as physico-chemical, biological, and advanced oxidation processes. Nonetheless, one of the membrane-based filtration methods, ultrafiltration, is considered as one of the technologies that promises the best micropollutant removal in water. With interesting properties including a moderate operating manner and great selectivity, this treatment approach is more popular than conventional ones. This study presents a comprehensive summary of EP’s existence in the environment, its toxicological consequences on health, and potential removal and treatment strategies.

Assessment of persistent organic pollutants in soil and sediments from an urbanized flood plain area

Polycyclic aromatic hydrocarbons (PAHs), organochlorine pesticides (OCPs) and phenolic compounds (PCs) are persistent organic compounds. Contamination of these potentially toxic organic pollutants in soils and sediments is most studied environmental compartments. In recent past, studies were carried out on PAHs, OCPs and PCs in various soils and sediments in India. But, this is the first study on these pollutants in soils and sediments from an urbanized river flood plain area in Delhi, India. During 2018, a total of fifty-four samples including twenty-seven each of soil and sediment were collected and analyzed for thirteen priority PAHs, four OCPs and six PCs. The detected concentration of ∑PAHs, ∑OCPs and ∑PCs in soils ranged between 473 and 1132, 13 and 41, and 639 and 2112 µg/kg, respectively, while their concentrations in sediments ranged between 1685 and 4010, 4.2 and 47, and 553 and 20,983 µg/kg, respectively. PAHs with 4-aromatic rings were the dominant compounds, accounting for 51 and 76% of total PAHs in soils and sediments, respectively. The contribution of seven carcinogen PAHs (7CPAHs) in soils and sediments accounted for 43% and 61%, respectively, to ∑PAHs. Among OCPs, p, p'-DDT was the dominant compound in soils, while α-HCH was found to be dominated in sediments. The concentrations of ∑CPs (chlorophenols) were dominated over ∑NPs (nitrophenols) in both the matrices. Various diagnostic tools were applied for the identification of their possible sources in soil and sediments. The observed concentrations of PAHs, OCPs and PCs were more or less comparable with the recently reports from various locations around the world including India. Soil quality guidelines and consensus-based sediment quality guidelines were applied for the assessment of ecotoxicological health effect.

Pesticides pollution and risk assessment of river Ganga: A review

Pesticides consumption along with its impact on different matrices of the environment has increased over past. Monitoring and risk assessment is important to know the exact scenario of pesticide toxicity of aquatic environment. The article compiles the number of studies on different stretches of river Ganga over past years. Risk quotient (RQ) method was used for the determination of potential risk of reported pesticides. Based on general (RQm) and worst-case (RQex) DDT and aldrin in the middle stretch of river Ganga show high risk. Regular monitoring along with compartmental studies is important to assess the pesticide pollution load and persistence in the river. Because hundreds of formulations are being used in the basin for agricultural purposes, detailed analysis and bio-magnification of all the pesticides should be appreciated.

Assessment of organochlorine pesticides and health risk in tobacco farming associated with River Barandu of Pakistan

Diffuse pesticide pollution through tobacco fields is a serious threat to both natural integrities and living beings because tobacco is known as a pesticide-intensive crop. Upsurge in the knowledge of detrimental impacts caused by organochlorine pesticides (OCPs) has made them a burning issue particularly in developing countries. Pakistan is a country famous for its agro-based economy and simultaneously is the second most significant pesticide consumer in South Asian countries. The studied area is tobacco hub of the country. Thus, the present work is aimed to investigate the contamination profile that highlights the ecological and health risk posed by OCPs in River Barandu, located in the proximity of tobacco farming region. ΣOCP levels in sediments ranged between 32.918 and 98.810 ng/g and in water between 0.340 and 0.935 μg/L. Hexachlorocyclohexanes (HCHs) and heptachlor were the most prevailing pesticides in both matrices of the river. Isomeric composition of DDTs and HCHs highlighted that the β-HCH and p,p'-DDT were dominant isomers in water, while α-HCH and p,p'-DDT in sediment compartment. Enantiomeric compositions of HCH and DDT indicate both recent and historic uses of these compounds in the area. Indirect contamination through nearby tobacco clusters has been depicted through spatial analysis. Ecological risk assessment based upon the risk quotient (RQ) method revealed that α-endosulfan, dieldrin, heptachlor, and ∑HCHs represent a very high level of ecological risks. The OCPs' lifetime carcinogenic and non-carcinogenic health risks associated with dermal exposure to river's water were considered nominal for surrounding populations. However, detailed ecological and health risk studies are recommended considering the bio-accumulating nature of these contaminants in the food chain.

Level of pesticides contamination in the major river systems: A review on South Asian countries perspective

Pesticides are chemical compounds used worldwide for different purposes. These chemicals are well known for their long life, high toxicity, and slow degradation process. Many developed countries including South Asian countries banned the use of pesticides for their adverse effects. However, several pesticides are found incessantly in water and soil. To highlight the recent situation of pesticide contamination in South Asian river systems, we have studied 136 relevant articles published from 2015 to 2020. Articles were gathered using several commonly available search engines and organized according to information related to river systems of South Asian countries. After thoroughly examining those research articles, we summarized that most of the river systems are contaminated by pesticides, where DDTs, HCHs, endosulfan, heptachlor, and chlorpyrifos are the key recognized compounds among them. Comparing the level of pesticides with standard guidelines, we found that the Tapi River and Chilika Lake of India are considerably more contaminated than other river basins. Multivariate analyses identified the industrial discharge and agricultural run-off of chemicals as the probable sources of pesticides in these rivers. By analyzing the amount of annual pesticide production, their use, and accordingly their considerable presence in the water systems of the South Asian countries, it is evident that the banned pesticides are used regularly by these countries and thus contaminating the environment. Therefore, the formulations of appropriate rules and their enforcement to control the manufacture and solicitation of such pesticides are an urgent need to save the environment.

Plasticizers and bisphenol A: Emerging organic pollutants along the lower stretch of River Ganga, north-east coast of the Bay of Bengal

Hooghly River (HR), the other name used for the lower stretch of River Ganga, is a prime freshwater source in the eastern part of India. However HR has been evidenced with a variety of emerging organic pollutants (EOPs) in the recent past. Given the extensive use of plasticizers and additive in plastic products, we have investigated seven plasticizers and bisphenol A (BPA) in the surface and storm-water of HR up to the tip of the Bay of Bengal. Further using a previously published sediment data we have estimated the fluxes for the aforementioned EOPs. Surface water and storm-water concentrations of seven plasticizers varied between 92.62 and 770 ng/L (176.1 ± 104.8; Avg ± SD) and 120.9-781.5 ng/L (355.2 ± 232.5), respectively. BPA varied between 43 and 8800 ng/L (658.3 ng/L ± 1760) and 117.9-2147 ng/L (459.3 ± 620.2) in surface and storm-water, respectively. With the increase in salinity, a decreasing trend for bis-(2-ethylhexyl) phthalate (DEHP) was evidenced. However, concentration of BPA increased with the increase in salinity. Significant and strong correlation between DEHP and BPA (R² = 0.6; p < 0.01) in the suburban corridor might have resulted from sludge disposal of the scrap recycling activities. Using site-specific principal component analysis, unregulated disposal of plastic waste, particularly from such industrial belts and tourist spots were identified as the possible point sources for plasticizers and BPA in this region. Net diffusive flux based on fugacity fraction showed a trend depending on the pollutant's aqueous solubility and partition coefficient. However, transfer tendency from water to sediment was noticed in the sites having point source. Estimated ecotoxicological risk posed by BPA was higher for edible fishes and for lower order organisms, PAEs was the major contributor.

Organochlorine pesticides and heavy metals in the zooplankton, fishes, and shrimps of tropical shallow tidal creeks and the associated human health risk

Studies on organochlorine pesticides (OCPs) and heavy metals (HMs) from tidal creeks are scarce. Sixteen OCPs and seven HMs were measured in the surface water, zooplankton, two fishes (Harpadon nehereus and Pampus argenteus), and one shrimp (Penaeus indicus) collected from three tidal creeks of the Indian Sundarban. The surface water was polluted by hexachlorocyclohexane isomers (ΣHCH: 525-1581 ng l^-1), dichlorodiphenyltrichloroethane congeners (ΣDDT: 188-377 ng l^-1), endosulfan congeners (ΣEND: 687-1474 ng l^-1), and other OCPs (512-1334 ng l^-1). However, the mean HM concentrations in the surface water were <1 μg l^-1. The zooplankton community exhibited bioaccumulation of both OCPs and HMs. Aldrin, Heptachlor, and α-HCH levels in the edible biotas could lead to cancer. Co and Cd levels could lead to non-cancerous risks, and Pb levels could pose a cancerous risk. This study showed that creeks could be potential sites of both OCP and HM pollution.

Phenolic compounds in water, suspended particulate matter and sediment from Weihe River in Northwest China

The distribution and ecological risks of 11 phenolic compounds were studied in Weihe River, Northwest China. The concentrations of phenolic compounds were determined by ultra-high performance liquid chromatography (UPLC). The total concentration of 11 phenolic compounds (∑PC₁₁) ranged from 0.06 to 14.12 μg/L with an average of 5.22 μg/L in water, from 0.92 to 34,885 μg/g with an average of 4,446 μg/g in suspended particulate matter (SPM), and from 3.54 to 34.09 μg/g with an average of 11.09 μg/g in sediment. For individual phenolic compound, the mean concentration of pentachlorophenol was the highest in water (2.65 μg/L) and in SPM (3,865 μg/g), while in sediment the mean concentration of 2,4,6-trichlorophenol was the highest (3.05 μg/g). The total concentration of 5 chlorophenols (∑CP₅) was significantly higher than that of 6 non-chlorophenols (∑NCP₆) in all three studied compartments. The phenolic compounds in Weihe River were at moderate levels in water and at high levels in sediment. The ecological risk assessment results indicated that phenolic compounds exhibited a high ecological risk in Weihe River water. In most sites, the distribution coefficient (Kd) (SPM) was much higher than Kd (sediment), which probably suggested fresh phenolic compounds input in Weihe River.

Pesticides contamination in the Thamirabarani, a perennial river in peninsular India: The first report on ecotoxicological and human health risk assessment

This study evaluates the distribution of pesticides and assesses the ecological and human health risks associated with pesticide residues concentration in the Thamirabarani River, the only perennial river in Tamil Nadu, India. Observed a variation in the pesticide concentration in the water (not detected (ND)-31.69 μg/L), sediments (ND-14.77 μg/kg), and fish (0.02-26.05 μg/kg). Endosulfan, aldrin, and endrin were the predominant organochlorine pesticides present in water, sediments, and fish. The average concentration of pesticides (except endosulfan) in water and sediments was found to be below the acceptable threshold as per the water and sediment quality guidelines, posing no ecological hazard to aquatic organisms. The calculated risk quotient and toxic unit (0.1 > TU/RQ ≤ 1) represent low-to-medium acute and chronic toxicity to the aquatic organisms inhabiting the river basin. The average concentration of pesticides in fish (Labeorohita) was also below the maximum residual limits set by the Codex Alimentarius Commission (CAC). However, the calculated daily intakes of endosulfan, aldrin, and endrin were above the CAC-acceptable daily intake guidelines. The human health risk assessment showed that children and adults exposed to pesticides in water and sediments through ingestion and dermal contact could have higher cancer risks (CR > 10^-4) than inhalation. This study recommends implementing effective and routine pollution management schemes to avoid pesticide threats to aquatic and human health.

Surveillance of plasticizers, bisphenol A, steroids and caffeine in surface water of River Ganga and Sundarban wetland along the Bay of Bengal: occurrence, sources, estrogenicity screening and ecotoxicological risk assessment

The transboundary River Ganga serves as a conduit for meltwater from the Himalayas and is a major freshwater source for two thirds of Indian population before emptying into the Sundarban Delta, the largest estuary in the Bay of Bengal. Endocrine disrupting compounds (EDCs) such as phthalic acid esters (PAEs) and bisphenol A (BPA) used as organic plastic additives can pollute the aquatic environment receiving plastic litter. Hence, we have investigated these EDCs in water samples from Ganga and Sundarban wetland of India. Since these compounds exhibit estrogenic potential, we have further measured steroids and evaluated the estrogenic activity (estradiol equivalents, BioE2Eqs) using an in-vitro bioassay (E-Screen). Further BioE2Eqs were compared with the sum of predicted estradiol equivalents based on the chemical concentrations of PAEs and BPA by E-Screen (ChemE2Eq) and YES factors (ChemYES). Caffeine was measured as a marker for anthropogenic wastewater discharge. Results showed that the highest BioE2Eq (below the lowest observable effect of E2 on fish) was associated with sites having sewer outfalls in the middle stretch of the river, and concomitantly coinciding with the elevated concentrations of caffeine. Neither ChemE2Eq nor ChemYES correlated with measured BioE2Eqs. River concentrations of BPA (0.04-4.46 µg/L) and ∑₇plasticizers (0.43-7.63 µg/L) were higher than BPA (0.21-2.82 µg/L) and ∑₇plasticizers (0.85-2 µg/L) in the Sundarban wetland. The only steroids detected were androgens, found at four sites in Ganga (0.007 µg/L± 0.003, mean ± S.D.). The highest estimated ecotoxicological risk to aquatic insect and fish stemmed from BPA. A secondary effect, and a potential impact on human health could be reflected via fish consumption from the productive fisheries region along the lower stretch of River Ganga. Identification of areas of elevated estrogenicity, plasticizer and steroid concentrations in River Ganga can be used to design and implement interventions for the remediation of such emerging contaminants.

Human exposure to organochlorine, pyrethroid and neonicotinoid pesticides: Comparison between urban and semi-urban regions of India

In developing countries, urban areas may be at greater risk of pesticide exposure compared to semi-urban agricultural regions. To investigate this, concentrations of selected pesticides were measured in 81 human milk samples collected in urban Kolkata and semi-urban Nadia in West Bengal, India. Three classes of pesticides were investigated - legacy organochlorines and emerging pyrethroids and neonicotinoids. The average concentration of the majority of the chemicals (DDT, its metabolites, HCH isomers, bifenthrin, endosulfan), showed a clear urban > semi-urban trend. Compared with previous measurements in other Indian cities and developing nations, current HCH and DDT concentrations in urban Kolkata were high. These chemicals were detected in 100% of the samples in both the urban and the semi-urban region. Also in both regions, the Estimated Daily Intake of DDTs, HCHs, aldrin, dieldrin and the pyrethroid bifenthrin for breastfed infants exceeded the Tolerable Daily Intake in a number of samples. Three pyrethroids were detected in human milk samples in India for the first time. This indicates a shift in the usage pattern of pesticides in India from organochlorines to pyrethroids. These findings may be used to drive targeted regulation of pesticides in developing countries with similar histories of pesticide use.

Health Risk Assessment, Composition, and Distribution of Polycyclic Aromatic Hydrocarbons (PAHs) in Drinking Water of Southern Jharkhand, East India

The studies on polycyclic aromatic hydrocarbons (PAHs) occurrence, distribution, health risk, and composition in drinking water are limited in India and worldwide. The main objective of this study was to find the contaminant sources, composition, health risk, and distribution of USEPA's 16 priority pollutant PAHs in the drinking water samples collected between July 2019 to September 2019 from six districts of Southern Jharkhand. The Σ_16PAHs mean ± standard deviation [SD] concentration values were ordered as East Singhbhum (ES) (21.5 ± 14.8 ng L^-1) > West Singhbhum (WS) (16.57 ± 13.21 ng L^-1) > Saraikela Kharsawan (SK) (11.48 ± 9.92 ng L^-1) > Khunti (KH) (10.32 ± 9.09 ng L^-1) > Simdega (SM) (9.96 ± 7.85 ng L^-1) > Gumla (GU) (9.41 ± 8.63 ng L^-1). The results show that ES and WS districts' groundwater samples were more contaminated by the PAHs, which may be attributed to the presence of many small-, medium-, and large-scale industries and high vehicular density in these districts. The concentrations of lower molecular weight ring (3-rings) and middle molecular weight ring (4-rings) PAHs were dominant throughout all drinking samples. The concentration of the 3-ring PAH Anthracene and 4-ring PAH Fluoranthene were dominant in all districts. The molecular ratios suggested that the potential sources of PAHs are fuel combustion and coal, grass, and wood burning. Risk assessment shows that the incremental lifetime cancer risk and risk index (RI) were ranged from 0.02 × 10^-10 to 4.93 × 10^-10 for children and 0.01 × 10^-10 to 2.98 × 10^-10 for adults. The RI values for seven carcinogenic PAHs were 8.83 × 10^-10 for children and 7.38 × 10^-10 for adults. Although the carcinogenic risks were within the permissible values, chronic exposure to PAHs through the ingestion of drinking water could still be a human health concern.

Distribution and ECo-Toxicological Risk Assessment of Legacy Persistent Organic Pollutants in Surface Water of Talar, Babolrood and Haraz Rivers

In the outer Alborz Range in the Northern Province of Iran, the Haraz, Talar and Babolrood Rivers are the three largest rivers where most of the agricultural, aquacultural and industrial activities are found. Total indicator polychlorinated biphenyls (iPCBs) ranged ND–474, ND–273 and ND–559 ng/L in Haraz, Talar and Babolrood Rivers, respectively. Significantly lower (p < 0.05) concentrations of DDT, lindane and dieldrin were observed in the upstream stations than downstream stations of both Babolrood and Haraz Rivers. However, in Talar River, PCB residues in upstream was significantly higher (p < 0.05) than downstream. Furthermore, PCB-28 in Talar River and PCB-101 and PCB-153 in Bablrood and Haraz Rivers were high in water samples at all stations. A significant difference was observed among the stations. In October, November and December, there was negligible variations in total PCB concentration among the stations. Alarming levels of some of the legacy persistent organic pollutants (POPs) may pose adverse effects on the aquatic species dwelling in the Talar, Babolrood and Haraz Rivers of Iran.

Legacy and current pesticide residues in Syr Darya, Kazakhstan: Contamination status, seasonal variation and preliminary ecological risk assessment

The Syr Darya is one of two major rivers in Central Asia supplying critical fresh water to the Aral Sea. In spite of the river's importance and agriculturally-intensive history, few studies have provided a modern evaluation of and the occurrence of pesticide residues potential effects to aquatic life. The primary goal of this investigation was to determine seasonal variations in ambient concentrations of modern and legacy pesticides in bottom sediment and water of the Syr Darya in Kazakhstan (KZ) downstream from an agriculturally-intensive watershed in Uzbekistan. Grab samples and passive samplers were used at five remote sampling stations during June 2015 to provide a baseline for ecotoxicological evaluation. Results were compared with samples collected during and after the agricultural growing season. Polar organic chemical integrative samplers (POCIS) were used in June and calibrated for time-weighted average concentrations of current use pesticides. Among legacy chlorinated pesticides measured in grab samples from the river, lindane (γ-HCH) was detected most frequently with the highest concentrations occurring during June. For all the sampling events, residues of lindane (γ-HCH) ranged from 0.014 to 0.24 μg/L detected in water samples, are among the highest concentrations reported for rivers globally. Concentrations of γ-HCH, p,p'-DDE and dieldrin were highest in October when dieldrin concentrations approached 0.4 μg/L. Sources of legacy pesticides may be either illicit upstream use or evidence of previous atmospheric contamination of glacial meltwater. Chronic exposure to these residues may lead to ecological risk to lower order organisms in both the sediment and water column.

Perturbations in glycerophospholipid levels of PC12 cells after exposure to PCB95 based on targeted lipidomics analysis

Polychlorinated biphenyls (PCBs) are a group of organic chlorine chemicals that can induce various adverse health effects in animals and humans. The toxicology of PCBs is a significant public health concern because of their long-term presence in the environment. Among the 209 PCB congeners, PCB95 has been reported to be neurotoxic, however, there has been limited researches on evaluating whether and how PCB95 affects cellular lipids, the most abundant components of the brain. In this study, PCB95 was found to inhibit cell proliferation at concentrations of 0.1 μM, 2 μM and 10 μM for 120 h. Additionally, there may be a shift in apoptosis to necrosis at 2 μM PCB95 exposure for 24 h. However, lipid peroxidation was found not dominant for PCB95 exposure, especially at the concentrations of 0.1 μM and 2 μM. Because of playing vital roles in cell metabolism, 20 glycerophospholipids in PC12 cells were investigated after exposure to PCB95 for 120 h. The distinctions in the orthogonal projection to latent structures-discriminant analysis (OPLS-DA) models indicated that different concentrations of PCB95 leaded to aberrant glycerophospholipid metabolism. Based on the principles of t-test P-value < 0.05, variable importance at projection (VIP) value >1 and fold change >1, PC (14:0/14:0) and PC (16:0/14:0) were screened as potential biomarkers from all the target glycerophospholipids. This study is the first time that identifies the effects of PCB95 on specific glycerophospholipids in PC12 cells, and the observed changes in glycerophospholipids provides the basis for further evaluation of PCB95-induced neurotoxicity mechanisms.

Organochlorine Pesticides in Surface Water of Jiuxi Valley, China: Distribution, Source Analysis, and Risk Evaluation

Residual levels of 11 organochlorine pesticides (OCPs) in surface water of Jiuxi Valley were determined during spring and autumn at nine sampling points to assess their contamination and potential risks. The water samples were extracted by solid-phase extraction (SPE), and OCPs were analyzed by gas chromatograph equipped with a 63Ni-ECD detector. The investigation results indicated that the concentration of total OCPs varied from 4.07 to 13.5 ng·L−1 with an average value of 7.15 ng·L−1 in spring, and from 12.5 to 30.1 ng·L−1 with an average value of 19.9 ng·L−1 in autumn. Jiuxi Valley was slightly contaminated by OCPs, and the concentrations of ΣHCHs and ΣDDTs in the river were at relatively low levels. HCHs were the main pollutant in spring, and also in autumn, and α-HCH was the main component of the HCH isomers at most sampling points. Source analysis indicated that local use of lindane or input of fresh γ-HCH contributed to the presence of HCHs. New inputs were the major sources of DDTs, aldrin, heptachlor, and endrin. The OCP levels of this investigation were within the standard limits set by a majority of the water quality standards and guidelines of China, WHO, European Union, and Canada. However, although the γ-HCH concentrations at all sampling sites, endrin concentrations at all sampling sites, and β-HCH concentrations at most sampling sites were below the human health water quality standard, and the levels of other tested OCPs (α-HCH, p,p′-DDD, p,p′-DDE, p,p′-DDT, aldrin, and heptachlor) exceeded the value of EPA-recommended water quality criteria for human health, which indicated potential risks to human health around the region.

Assessment of polychlorinated biphenyls (PCBs) in the Himalayan Riverine Network of Azad Jammu and Kashmir

The emission of polychlorinated biphenyls (PCBs) in South Asian countries is one of the great environmental concerns and has resulted in the contamination of surrounding high altitude regions such as Azad Jammu and Kashmir (AJK), Pakistan. This first investigation of Polychlorinated Biphenyl (PCBs) concentrations in the ambient air, water and surface soil was conducted along the extensive stream network in the AJK valley of the Himalayan Region. In 2014, surface soil samples were taken and passive air and water samplers were deployed along the four main rivers, namely Jhelum, Neelum, Poonch and Kunhar, and analysed for PCBs (33 congeners) using GC-MS/MS. The ∑₃₃PCBs concentrations ranged from 31.17 to 175.2 (mean ± SD: 81 ± 46.4 pg/L), ND to 1908 (1054 ± 588.5 pg/g), and 29.8 to 94.4 (52.9 ± 22.7 pg/m³) in surface water, soil and air matrices, respectively. The levels of dioxin-like PCBs (∑₈DL-PCBs) contributed considerably towards the total PCBs concentrations: 60.63% (water), 43.87% (air) and 13.76% (soil). The log transformed air-water fugacity (log fa/fw) ratios ranged from -9.37 to 2.58; with 86.3% of the sampling sites showing net volatilization of selected PCB congeners. Similarly, the fugacity fractions for air-soil exchange exhibited narrow variation (0.8 to < 1) indicating net volatilization of PCBs. The ecological risk assessment showed low potential ecological risks (E_rⁱ  = 1.58-7.63) associated with PCB contamination. The present findings provide baseline data that suggest cold trapping of POPs in the remote mountainous areas of Pakistan and can support environmental management of POPs at the regional level. This pioneer investigation campaign to assess the PCBs concentrations in Himalayan Riverine Network of Azad Jammu and Kashmir, Pakistan helps to develop baseline data of PCBs from the strategically important riverine environment that would help in future regional as well as global ecological studies. However, the effects of temperature variations on the sampling rates of chemicals across a wide spectrum of volatility along the elevation gradient were not taken under consideration for PCBs atmospheric concentrations.

Spatial distribution and sources of pesticidal persistent organic pollutants in the Hooghly riverine sediment

Given the extensive indiscriminate usage in the past and limited ongoing use, organochlorine pesticides (OCPs) have been widely reported in the Hooghly riverine environment. Hence, surface riverine sediment samples were collected along the urban and suburban transects of the Hooghly River and OCPs were quantified in gas chromatography mass spectrometry (GC-MS). Mean concentration of HCH, DDT, and endosulfan was 5 ng g^-1, 10 ng g^-1, and 4 ng g^-1 respectively. DDT was dominant among all the OCPs and contributed nearly 40% to the total OCPs possibly due to the ongoing use of DDT for vector control programs. Diagnostic ratios suggest recent source of lindane, DDT, and endosulfan. Using OCP concentration from previously published data in surface water during the same time frame, sediment-water partitioning of OCPs was estimated. Excluding α-HCH and γ-HCH in few pockets, majority of the OCPs tend to partition more on to sediment. Comparing the sediment concentration with the sediment quality guideline values, risk on ecological integrities was indicated due to DDT and HCH contamination. Suburban sites indicated higher risk than urban sites according to the calculated sediment quality guideline quotient (SQGQ). A brief review on the approach to pesticidal POP pollution management in India revealed that older management approaches should be replaced with a unique, integrated, and holistic system.

Adaptive co-management model for the East Kolkata wetlands: A sustainable solution to manage the rapid ecological transformation of a peri-urban landscape

Human-induced land use changes like agriculture and urban development occur commonly at the cost of natural wetlands, which require immediate attention and sustained efforts from urban planners and concerned governments. In view of the East Kolkata Wetlands (EKW), India, this paper has examined the trend, causes, extent and impacts of landscape transformation during the last few decades. Hence we aim to present a review of several studies in and around EKW and suggests a sustainable model for EKW. This 'Ramsar site of International Importance' is one of the world's largest wastewater-fed aquaculture systems where the city sewage is recycled for pisciculture and agriculture, and acts as flood resistance for the city of Kolkata. Rapid encroachment in the EKW due to unplanned development has caused various environmental, social and economic impacts. The key ecological impacts found in the study included loss of faunal and floral diversity, eco-toxicological impacts, etc. In terms of biodiversity loss, while the number of bird species in the EKW decreased from 248 in 1960s to 72 in 2005, about 59% fish species are near threats, vulnerable and endangered. Reported persistent organic pollutants (POPs) around the EKW region were found to pose deleterious impact on environment and ambient biota. Several studies have evidenced that the open burning of solid waste in the dumping ground of Dhapa is a potential source of polychlorinated biphenyls (PCBs) and polychlorinated dibenzo dioxin/furans (PCDD/Fs). Further the ecological transformation of the EKW focussing on policy development and regulatory compliance issues has been studied in this paper. The aspects of encroachment and wetland shrinkage triggered by economic drivers like urban sprawl have been analyzed. The paper presents adaptive co-management as the future roadmap for action to curb further degradation of the wetlands, and adopt an integrated approach of environmental, political, physical, economic and institutional aspects. It is envisaged that the adaptive co-management model will contribute to long-term sustainable sustenance of this precious ecosystem.

Occurrence and risk evaluation of organochlorine contaminants in surface water along the course of Swartkops and Sundays River Estuaries, Eastern Cape Province, South Africa

Organochlorine contaminants were analysed in surface water from Sundays (SDE) and Swartkops Estuaries (SWE), Eastern Cape Province, which is among the largest estuaries in South Africa. The concentration of Σ₁₈OCPs ranged from 16.7 to 249.2 ng/L in autumn, 19.9-81.4 ng/L in winter, 43.6-126.8 ng/L in spring and 68.3-199.9 ng/L in summer for SDE, whereas in SWE, the values varied from 20.9 to 259.7 ng/L in autumn, 58.9-263.9 ng/L in winter, 3.2-183.6 ng/L in spring and 118.0-188.9 ng/L in summer. Among all OCPs, α-HCH, β-HCH, p,p'-DDE, p,p'-DDT, endrin, dieldrin and endrin aldehyde were predominant in surface water samples from SDE and SWE. Furthermore, the mean concentration of polychlorinated biphenyls (PCBs) ranged from 126.7 ng/L in winter to 151.0 ng/L in spring for SDE and 249.0 ng/L in spring to 727.6 ng/L in winter for SWE. Tri- and tetra-PCBs dominated the PCB homologue profile. Hierarchical cluster analysis grouped the study sites into three regions from least polluted to most polluted, indicated that SWE is more polluted compared to SDE, probably due to the influx of agricultural and industrial effluents. Carcinogenic and non-carcinogenic risk assessment revealed that the water from both estuaries is not safe for drinking, although suitable for bathing.

Air-water exchange of pesticidal persistent organic pollutants in the lower stretch of the transboundary river Ganga, India

The lower stretch of the perennial transboundary river Ganga is known as the Hooghly River (HR) in India. Despite the strict ban, HR has been evidenced with residues of pesticidal persistent organic pollutants (POPs) from primary and secondary sources. Hence surface water sampling and passive air sampling (PAS) were conducted along the urban and suburban transects and discharge points to study the fate of pesticidal (POPs along the HR. Excluding the discharge points, the mean concentration of hexachlorocyclohexane (HCH), dichlorodiphenyltrichloroethane (DDT) and endosulfan (ENDO) were 6 ng/L, 4 ng/L and 36 ng/L in surface water and 888 pg/m³, 1689 pg/m³ and 429 pg/m³ in atmosphere respectively. Percentage composition and diagnostic ratios strongly suggest ongoing use of technical HCH, DDT and endosulfan. Elevated endosulfan in surface water has been related to its usage during fishing. Except for p,p'-DDE, α-Endo and β-Endo, fluxes at the air-water interface showed net deposition from air to water for all the OCPs in urban and suburban transects. The estimated eco-toxicological risk assessment showed risk on lower trophic organisms due to DDT and lindane mostly at the discharge points. Endosulfan can pose potential risk to the edible fishe species in the HR.

Spatiotemporal distribution, source apportionment and ecological risk assessment of PBDEs and PAHs in the Guanlan River from rapidly urbanizing areas of Shenzhen, China

In this study, nine congeners of polybrominated diphenyl ethers (PBDEs) and sixteen congeners of polycyclic aromatic hydrocarbons (PAHs) were measured in water samples to elucidate their spatial distribution, congener profiles, sources and ecological risks in the Guanlan River during both the dry season (DS) and the wet season (WS). The concentration of Σ₉PBDE ranged from 58.40 to 186.35 ng/L with an average of 115.72 ng/L in the DS, and from 8.20 to 37.80 ng/L with an average of 22.15 ng/L in the WS. Meanwhile, the concentration of Σ₁₆PAHs was ranged from 121.80 to 8371.70 ng/L with an average of 3271.18 ng/L in the DS and from 1.85 to 7124.25 ng/L with an average of 908.11 ng/L in the WS. The concentrations of PBDEs and PAHs in the DS were significantly higher than those in the WS, probably due to the dilution of the river during the rainy season. Moreover, the spatial distribution of pollutants revealed decreasing trend in the concentration from upstream to downstream and almost identical pattern was observed during both seasons. The source apportionment suggested that penta-BDE and to some extent octa-BDE commercial products were major sources of PBDEs in the study area. However, the sources of PAHs were mainly comprised of fossil fuels and biomass burning, followed by the petroleum products and their mixtures. The results of the ecological risk assessment indicated PBDEs contamination posed high ecological risks, while PAHs exhibited low or no ecological risks in the study area. Consistent with the environmental levels, the ecological risks of pollutants were relatively lower in the WS, compared to that in the DS. The results from this study would provide valuable baseline data and technical support for policy makers to protect the ecological environment of the Guanlan River.

Organic micropollutants in the surface riverine sediment along the lower stretch of the transboundary river Ganga: Occurrences, sources and ecological risk assessment

The Hooghly River (HR) estuary is the first deltaic off-shoot of the perennial and transboundary river, Ganga, India. HR receives industrial and domestic waste along with storm-water run-off from Kolkata city and the adjoining districts. Organic micropollutants (OMPs) have been collectively termed for plasticizers, pharmaceuticals and personal care products, which are extensively consumed and disposed in the waste streams. Hence emerging OMPs were investigated to obtain the first baseline data from the Hooghly riverine sediment (HRS) along urban and suburban transects using gas chromatography mass spectrometry (GC-MS). The concentration range of OMPs in the HRS varied between 3 and 519 ng/g for carbamazepine, 5-407 ng/g for non-steroidal anti-inflammatory drugs (NSAIDs), 2-26 ng/g for musk ketone, 2-84 ng/g for triclosan, 2-199 ng/g for bisphenol A (BPA), 2-422 ng/g for plasticizers (phthalic acid esters (PAEs) and bis (2-ethylhexyl) adipate (DEHA)) and 87-593 ng/g for parabens. Carbamazepine concentration in sediment was an useful marker for untreated wastewater in urban waterways. High concentrations of BPA and PAEs in the suburban industrial corridor together with significant correlation between these two type of OMPs (r² = 0.5; p < 0.01) likely reflect a common source, possibly associated with the plastic and electronic scrap recycling industries. Among all the categories of OMPs, plasticizers seems to exhibit maximum screening level ecological risk through out the study area.

Persistent organic pollutants in the polar regions and the Tibetan Plateau: A review of current knowledge and future prospects

Due to their low temperatures, the Arctic, Antarctic and Tibetan Plateau are known as the three polar regions of the Earth. As the most remote regions of the globe, the occurrence of persistent organic pollutants (POPs) in these polar regions arouses global concern. In this paper, we review the literatures on POPs involving these three polar regions. Overall, concentrations of POPs in the environment (air, water, soil and biota) have been extensively reported, with higher levels of dichlorodiphenyltrichloroethane (DDT) and hexachlorocyclohexane (HCH) detected on the Tibetan Plateau. The spatial distribution of POPs in air, water and soil in the three polar regions broadly reflects their distances away from source regions. Based on long-term data, decreasing trends have been observed for most "legacy POPs". Observations of transport processes of POPs among multiple media have also been carried out, including air-water gas exchange, air-soil gas exchange, emissions from melting glaciers, bioaccumulations along food chains, and exposure risks. The impact of climate change on these processes possibly enhances the re-emission processes of POPs out of water, soil and glaciers, and reduces the bioaccumulation of POPs in food chains. Global POPs transport model have shown the Arctic receives a relatively small fraction of POPs, but that climate change will likely increase the total mass of all compounds in this polar region. Considering the impact of climate change on POPs is still unclear, long-term monitoring data and global/regional models are required, especially in the Antarctic and on the Tibetan Plateau, and the fate of POPs in all three polar regions needs to be comprehensively studied and compared to yield a better understanding of the mechanisms involved in the global cycling of POPs.