Sources, distribution, and risk assessment of organochlorine pesticides in Nairobi City, Kenya

Seasonal hot spots of pollution and risks in Western Kenya: A spatial-temporal analysis of almost 800 organic micropollutants

The release of chemicals into the environment presents a significant threat to aquatic ecosystems dependent on the proximity to emission sources and seasonal dynamics of emission and mobilization. While spatial-temporal information on water pollution in Europe is increasing, there are substantial knowledge gaps on seasonal pollution dynamics in tropical countries. Thus, we took Lake Victoria South Basin in western Kenya as a case study to identify spatial and seasonal hot spots of contamination, quantified toxic risks to different groups of organisms, and identified seasonal risk drivers. For this purpose, we analyzed grab water samples from five rivers with agricultural and wastewater treatment plants in their catchment in four different seasons. We used liquid chromatography coupled to high resolution mass spectrometry (LC-HRMS) with a target list of 785 organic micropollutants. A total of 307 compounds were detected with concentrations ranging from 0.3 ng/L to 6.6 μg/L. Using a Toxic Unit (TU) approach based on mixture toxicity to standard test organisms, crustaceans were identified as the most affected group followed by algae and fish. For crustaceans, chronic risk thresholds were exceeded in 96 % of all the samples, while 56 % of all samples are expected to be acutely toxic, with the highest risk in February during the dry season. High toxic unit values for algae and fish were recorded in July dry season and May wet season. Diazinon, imidacloprid, clothianidin and pirimiphos-methyl were the major drivers for crustacean toxicity while triclosan and different herbicide mixtures drive risks to algae in dry and wet seasons, respectively. A total of 18 chemicals were found to exceed acute and chronic environmental risk thresholds. With this study, strong spatial-temporal patterns of pollution, risks and risk drivers could be confirmed informing prioritization of monitoring and abatement to enhance water quality and reduce toxic risks.

Strategies for mitigation of pesticides from the environment through alternative approaches: A review of recent developments and future prospects

Chemical-based peticides are having negative impacts on both the healths of human beings and plants as well. The World Health Organisation (WHO), reported that each year, >25 million individuals in poor nations are having acute pesticide poisoning cases along with 20,000 fatal injuries at global level. Normally, only ∼0.1% of the pesticide reaches to the intended targets, and rest amount is expected to come into the food chain/environment for a longer period of time. Therefore, it is crucial to reduce the amounts of pesticides present in the soil. Physical or chemical treatments are either expensive or incapable to do so. Hence, pesticide detoxification can be achieved through bioremediation/biotechnologies, including nano-based methodologies, integrated approaches etc. These are relatively affordable, efficient and environmentally sound methods. Therefore, alternate strategies like as advanced biotechnological tools like as CRISPR Cas system, RNAi and genetic engineering for development of insects and pest resistant plants which are directly involved in the development of disease- and pest-resistant plants and indirectly reduce the use of pesticides. Omics tools and multi omics approaches like metagenomics, genomics, transcriptomics, proteomics, and metabolomics for the efficient functional gene mining and their validation for bioremediation of pesticides also discussed from the literatures. Overall, the review focuses on the most recent advancements in bioremediation methods to lessen the effects of pesticides along with the role of microorganisms in pesticides elimination. Further, pesticide detection is also a big challenge which can be done by using HPLC, GC, SERS, and LSPR ELISA etc. which have also been described in this review.

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.

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

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

Seasonal variations in air concentrations of 27 organochlorine pesticides (OCPs) and 25 current-use pesticides (CUPs) across three agricultural areas of South Africa

For decades pesticides have been used in agriculture, however, the occurrence of legacy organochlorine pesticides (OCPs) and current-use pesticides (CUPs) is poorly understood in Africa. This study investigates air concentrations of OCPs and CUPs in three South African agricultural areas, their spatial/seasonal variations and mixture profiles. Between 2017 and 2018, 54 polyurethane foam-disks passive air-samplers (PUF-PAS) were positioned in three agricultural areas of the Western Cape, producing mainly apples, table grapes and wheat. Within areas, 25 CUPs were measured at two sites (farm and village), and 27 OCPs at one site (farm). Kruskal-Wallis tests investigated area differences in OCPs concentrations, and linear mixed-effect models studied differences in CUPs concentrations between areas, sites and sampling rounds. In total, 20 OCPs and 16 CUPs were detected. A median of 16 OCPs and 10 CUPs were detected per sample, making a total of 11 OCPs and 24 CUPs combinations. Eight OCPs (trans-chlordane, o,p'-/p,p'-dichlorodiphenyldichloroethylene (DDE)/dichlorodiphenyltrichloroethane (DDT), endosulfan sulfate, γ-hexachlorocyclohexane and mirex) and two CUPs (carbaryl and chlorpyrifos) were quantified in all samples. p,p'-DDE (median 0.14 ng/m³) and chlorpyrifos (median 0.70 ng/m³) showed the highest concentrations throughout the study. Several OCPs and CUPs showed different concentrations between areas and seasons, although CUPs concentrations did not differ between sites. OCPs ratios suggest ongoing chlordane use in the region, while DDT and endosulfan contamination result from past-use. Our study revealed spatial and seasonal variations of different OCPs and CUPs combinations detected in air. Further studies are needed to investigate the potential cumulative or synergistic risks of the detected pesticides.

Relationship between Respiratory Morbidity and Environmental Exposure to Organochlorine Pesticides in Armenia

BACKGROUND

Many studies have investigated the effects of organochlorine pesticides (OCPs) on adverse health outcomes. However, studies addressing the link between respiratory health and OCPs are limited. Organochlorine pesticides are stable compounds and belong to the class of endocrine disrupting chemicals that represent a threat to global health.

OBJECTIVES

The aim of the present study was to examine the association between respiratory morbidity and environmental exposure to OCPs in selected regions in Armenia.

METHODS

The study was carried out in Lori and Gegharkunik provinces/marzes. The prevalence rate (per 100 000 population) and the average chronological indicators (ACh) for all respiratory diseases and asthma were calculated. Concentrations of OCPs (γ-hexachlorocyclohexane (γ-HCH), dichloro-diphenyl-trichloroethane [DDT], dichlorodiphenyldichloroethylene (DDE) and dichloro-diphenyl-dichloroethane (DDD)) were determined in soil and plant product samples and the average annual total concentration (AATC) of OCPs (γ-HCH + 4,4'-DDT + 4,4'-DDE+4,4'-DDD) was calculated.

RESULTS

The ACI for all respiratory diseases showed a growth tendency in areas of Gegharkunik province ranging from 14.2 to 20.9% and an increase in asthma ranging from 9.4% to 174.6%. The highest levels of AATC of OCPs were found in soil sampled in Gegharkunik province: 9.48 ± 1.11 μg/kg and 8.10 ± 1.05 μg/kg and these levels differed significantly from those in Lori (p=0.01-0.0007). The AATC of OCPs in plant products from Gegharkunik was also statistically higher: 1.83±0.13 μg/kg, in comparison with that of Lori province 1.31±0.09 μg/kg (p = 0.001 - 0.0000).

CONCLUSIONS

The results indicate that the increased tendency of respiratory diseases and asthma could be related to OCP residues found in soil and plant products in Gegharkunik province. However, the role of OCPs should not be ignored. Further research is needed to study OCP contamination dynamics and clarify the role of OCPs in respiratory morbidity.

COMPETING INTERESTS

The authors declare no competing financial interests.