Legacy persistent organochlorine pollutants and polycyclic aromatic hydrocarbons in the surface soil from the industrial corridor of South India: occurrence, sources and risk assessment

Polychlorinated biphenyls in bovine milk from a typical informal electronic waste recycling and related source regions in southern India before and after the COVID-19 pandemic outbreak

For more than a decade, Chennai city in southern India has been evidenced with informal electronic waste (e-waste) recycling and open burning practices as the potential sources for polychlorinated biphenyls (PCBs). PCBs can bioaccumulate in livestock particularly cows grazing on the contaminated soil. The outbreak of the COVID-19 pandemic led to additional challenges associated with waste management practices. Hence this study aims to elucidate twenty-five PCB congeners in bovine milk from the previously reported PCB source regions in Chennai and the suburbs before and after about three years of the pandemic outbreak along electronic waste recycling (EWR), open burning dumps (OBD), and residential (RES) transects. The geomean concentration of Ʃ25PCBs in ng/g lipid weight (lw) followed a decreasing trend of EWR (13 ng/g lw) > OBD (8 ng/g lw) > RES (4 ng/g lw). Over 80 % of PCBs stemmed from EWR and OBD transects before and after the pandemic. However, a significant surge in the level of PCB-52 was observed in the OBD transect after the pandemic outbreak. Most toxic PCB congeners, PCB-126 and -169 were significant contributors to TEQs in EWR and OBD transects and can be reasoned with the burning of waste materials and mixed plastics in these transects. The highest average daily dose (ADD) exposure risk was for children from EWR and was significantly higher (p < 0.05) than other transects. Mean ADD-induced TEQ (6.6 pg TEQ/kg-bw/day) from the cows grazing around Kodungaiyur dumpsite slightly exceeded the EU guideline of 5.5 pg TEQ/kg-bw/day after the outbreak of the pandemic due to PCB-126. However, none of the samples exceeded the US FDA (1.5μg/g milk fat) recommendation limits for PCBs in milk fat. Prolonged exposure to such persistent organic pollutants interlinked with the burning of mixed waste in the open dumps can be a public health concern.

Association between combined exposure to dioxins and arthritis among US adults: a cross-sectional study

Dioxins and dioxin-like compounds (DLCs) are common pollutants hazardous to human health. We applied 12 dioxins and DLCs data of 1851 participants (including 484 arthritis patients) from National Health Examination Survey (NHANES) 2001-2004 and quadrupled them into rank variables. Multivariate logistic regression, weighted quantile sum (WQS) regression, and Bayesian kernel machine regression (BKMR) models were used to explore the relationship between individual or mixed exposure to the pollutants and arthritis after adjusting for multiple covariates. In multivariable logistic regression with an individual dioxin or DLC, almost every chemical was significantly positively associated with arthritis, except PCB66 (polychlorinated biphenyl 66) and 1,2,3,4,6,7,8-heptachlorodibenzofuran (hpcdf). The WQS model indicated that the combined exposure to the 12 dioxins and DLCs was positively linked to arthritis (OR: 1.884, 95% CI: 1.514-2.346), with PCB156 (weighted 0.281) making the greatest contribution. A positive trend between combined exposure and arthritis was observed in the BKMR model, with a posterior inclusion probability (PIP) of 0.987 for PCB156, which was also higher than the other contaminants.

Spatial distribution and risk assessment of polycyclic aromatic hydrocarbons in soils from contaminated sites in Eastern China

A total of 16 polycyclic aromatic hydrocarbons (PAHs) were measured in 28 soil column samples from two contaminated industrial sites in Eastern China. The total concentration of 16 PAHs (∑PAHs) in the surface soil (0-20 cm) was measured up to 52,600 ng/g (dry weight basis) with a remarkable spatial difference in the studied contaminated sites. The concentrations of the ∑PAHs in soils decreased with the increase in soil depth (0-10 m). The surface and subsurface soil presented a tenfold higher concentration than the soil with depth greater than 4 m. Additionally, the vertical migration tendency of the PAHs was found to be correlated significantly with their hydrophobicity (R2 = 0.79, P < 0.01). Naphthalene (with lowest octanol-water partition coefficient among the studied PAHs) showed the greatest average soil depth at which its peak concentration occurred. Furthermore, risk quotient analysis by using benzo[a]pyrene as reference compound showed that 71.4% of the samples exhibited high ecological risk for soil. Moreover, the total carcinogenic risk of the PAHs in the surface soil samples was assessed at 5.61 × 10-5-1.28 × 10-4 and 4.41 × 10-6-9.43 × 10-5 for male and female workers, respectively, in which 67.9%-71.4% of the samples showed potential risk. Generally, these results suggest a further consideration of ecological and health risks associated with PAHs in contaminated sites in Eastern China.

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

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

New and legacy pesticidal persistent organic pollutants in the agricultural region of the Sultanate of Oman

Comprehensive air and surface soil monitoring was conducted for new and legacy organochlorine pesticides (OCPs) to fill the knowledge and data gap on the sources and fate of pesticidal persistent organic pollutants (POPs) in the Sultanate of Oman. DDTs in agricultural soil samples ranged from 0.013 to 95.80 ng/g (mean: 8.4 ± 25.06 ng/g), with a median value of 0.07 ng/g. The highest concentration was observed at Shinas, where intensive agricultural practice is prevalent. The dominance of p,p'-DDT in soil and air reflected technical DDT formulation usage in Oman. Among newly enlisted POPs, pentachlorobenzene had the maximum detection frequency in air (47%) and soil (41%). Over 90% of sites reflected extensive past use of hexachlorobenzene. Major OCP isomers and metabolites showed net volatilisation from the agricultural soil, thereby indicating concurrent emission and re-emission processes from the soil of Oman. However, the cleansing effect of oceanic air mass is the possible reason for relatively lower atmospheric OCP levels from a previous study. Although DDT displayed maximum cancer risk, the level is below the permissible limit. DDT primarily stemmed from obsolete stock and inadequate management practices. Hence, we suggest there is a need for DDT regulation in Oman.

Seasonal variations and associated health risks of polychlorinated naphthalenes in Markman Canal, Eastern Cape Province, South Africa

This study focused on evaluation of the levels, seasonal variations and human health risks associated with polychlorinated naphthalenes (PCNs) in water and sediment samples of Markman Canal using solid phase and soxhlet extraction methods respectively, followed by clean-up and quantification with gas chromatograph coupled with microelectron capture detector. The sum of eight PCNs congener's (∑₈PCNs) in water and sediments varied from 0.035 to 0.699 μg/L and 0.260 to 6744.16 μg/kg dw, respectively. Highest PCNs concentrations were recorded in water during winter, while sediment samples collected during spring contained maximum levels. The estimated toxic equivalency (TEQ) for water and sediments was 1.19 × 10^-7-1.47 × 10^-4 µg/L and 4.43 × 10^-5-4.19 × 10^-1 µg/kg consecutively. The PCN levels and TEQ values revealed that this waterbody is polluted but constitutes no excess health risk. Efforts should be made to control all the activities contributing to pollution of this canal.

Combined exposure to multiple dioxins and dioxin-like polychlorinated biphenyls on hypertension among US adults in NHANES: a cross-sectional study under three statistical models

Dioxins and dioxin-like polychlorinated biphenyls (DL-PCBs) are mainly released as by-products of human activities, often in the form of mixtures, and the potential harm on human health deserves attention. Therefore, our study aimed to analyze the combined effect of dioxins and DL-PCB exposures on hypertension (HTN) among US adults. Data of eligible participants were acquired from the National Health and Nutrition Examination Survey (NHANES). Multiple logistic regression models with adjustment for covariates were applied to explore the associations between 13 persistent organic pollutants (POPs) and HTN. Stratified analyses and interaction analyses were then conducted by age and gender. Finally, the combined effects of dioxins and DL-PCBs on HTN were assessed by the weighted quantile sum (WQS) model and the Bayesian kernel machine regression (BKMR) model. A total of 976 adults were included in our study, of whom 397 had HTN. Spearman correlations indicated positive correlations among 13 POPs. And most of them (except PCB28, PCB66, and 1,2,3,4,7,8,9-hpcdf) had significant effects on HTN. The result of WQS revealed that mixed exposure to dioxins and DL-PCBs was significantly associated with increased risk of HTN (OR: 2.205; 95% CIs: 1.555, 3.127). The BKMR model also presented a positive trend of HTN risk with exposure to multiple dioxins and DL-PCBs. And 1,2,3,4,6,7,8,9-ocdd may be the main factor for this positive association. Considering the limitations of our cross-sectional study with the small sample, further prospective studies are necessary to validate our findings.

The environmental distribution and removal of emerging pollutants, highlighting the importance of using microbes as a potential degrader: A review

Emerging pollutants (EPs) create a worldwide concern owing to their low concentration and severe toxicity to the receptors. The prominent emerging pollutants categories as pharmaceutical and personal care product, plasticizer, surfactants, and persistent organic pollutants. Typically, EPs are widely disseminated in the aquatic ecosystem and capable of perturbing the physiology of water bodies as well as humans. The primary sources of EPs in the environment include anthropogenic release, atmospheric deposition, untreated or substandard treated wastewater, and extreme weather events. Intensive research has been done covering the environmental distribution, ecological disturbance, fate, and removal of EPs in the past decades. However, a systematic review on the distribution of EPs in the engineered and natural aquatic environment and the degradation of different EPs by using anaerobic sludge, aerobic bacteria, and isolated strains are limited. This review article aims to highlight the importance, application, and future perceptions of using different microbes to degrade EPs. Overall, this review article illustrates the superiority of using non-cultivable and cultivable microbes to degrade the EPs as an eco-friendly approach. Practically, the outcomes of this review paper will build up the knowledge base solutions to remove EPs from the wastewater.