Pesticide Research on Environmental and Human Exposure and Risks in Sub-Saharan Africa: A Systematic Literature Review

Association of pesticide exposure with neurobehavioral outcomes among avocado farmworkers in Mexico

BACKGROUND AND AIM

To date, few studies have focused on the health effects of pesticide exposure among avocado farmworkers. We examined the association of exposure to insecticides, fungicides, and herbicides with cognitive and mental health outcomes among these avocado workers from Michoacan, Mexico.

MATERIALS AND METHODS

We conducted a cross-sectional study of 105 avocado farmworkers between May and August 2021. We collected data on self-reported pesticide use during the 12 months prior to the baseline survey and estimated annual exposure-intensity scores (EIS) using a semi-quantitative exposure algorithm. We calculated specific gravity adjusted average concentrations of 12 insecticide, fungicide, or herbicide metabolites measured in urine samples collected during two study visits (8-10 weeks apart). We assessed participants' cognitive function and psychological distress using the NIH Toolbox Cognition Battery and the Brief Symptom Inventory 18 (BSI-18), respectively. We examined individual associations of EIS and urinary pesticide metabolites with neurobehavioral outcomes using generalized linear regression models. We also implemented Bayesian Weighted Quantile Sum (BWQS) regression to evaluate the association between a pesticide metabolite mixture and neurobehavioral outcomes.

RESULTS

In individual models, after adjusting for multiple comparisons, higher concentrations of hydroxy-tebuconazole (OH-TEB, metabolite of fungicide tebuconazole) were associated with higher anxiety (IRR per two-fold increase in concentrations = 1.26, 95% CI:1.08, 1.48) and Global Severity Index (GSI) (IRR = 1.89, 95% CI:1.36, 2.75) scores, whereas higher concentrations of 3,5,6-trichloro-2-pyridinol (TCPy, metabolite of chlorpyrifos) were associated with lower GSI scores (IRR = 0.69, 95% CI: 0.56, 0.85). In BWQS analyses, we found evidence of a mixture association of urinary pesticide metabolites with higher anxiety (IRR = 1.72, 95% CrI: 1.12, 2.55), depression (IRR = 4.60, 95% CrI: 2.19, 9.43), and GSI (IRR = 1.99, 95% CrI: 1.39, 2.79) scores. OH-TEB and hydroxy-thiabendazole (metabolite of fungicide thiabendazole) combined contributed 54%, 40%, and 54% to the mixture effect in the anxiety symptoms, depression symptoms, and overall psychological distress models, respectively.

CONCLUSIONS

We found that exposure to tebuconazole and thiabendazole, fungicides whose effects have been rarely studied in humans, may be associated with increased psychological distress among avocado farmworkers. We also observed that exposure to chlorpyrifos may be associated with decreased psychological distress.

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.

Parkinson's Disease in Sub-Saharan Africa: Pesticides as a Double-Edged Sword

Long-term exposure to pesticides used in agriculture is increasingly being identified as a risk factor for developing Parkinson's disease. How chronic pesticide exposure might contribute to the growth of Parkinson's disease in the mainly agricultural communities of Sub-Saharan Africa has thus far received limited attention. There are specific concerns in this area of the world: aging of the population, in combination with chronic exposure to widely used pesticides, including those that have been restricted elsewhere in the world because of neurotoxicity and other health risks. Of interest, the prevalence of Parkinson's disease among specific (semi)nomadic populations in Tanzania seems very low, possibly due to their lack of exposure to agricultural chemicals. But at the same time, pesticides have also brought important benefits to this part of the world. Specifically, in Sub-Saharan Africa, pesticides have been directly helpful in preventing and controlling famine and in containing major human infectious diseases. This creates a complex risk-benefit ratio to the use of pesticides within a global perspective, and urgently calls for the development and implementation of affordable alternatives for areas such as Sub-Saharan Africa, including non-neurotoxic compounds and non-chemical alternatives for the use of pesticides.

The Body, the Brain, the Environment, and Parkinson's Disease

The brain- and body-first models of Lewy body disorders predict that aggregated alpha-synuclein pathology usually begins in either the olfactory system or the enteric nervous system. In both scenarios the pathology seems to arise in structures that are closely connected to the outside world. Environmental toxicants, including certain pesticides, industrial chemicals, and air pollution are therefore plausible trigger mechanisms for Parkinson's disease and dementia with Lewy bodies. Here, we propose that toxicants inhaled through the nose can lead to pathological changes in alpha-synuclein in the olfactory system that subsequently spread and give rise to a brain-first subtype of Lewy body disease. Similarly, ingested toxicants can pass through the gut and cause alpha-synuclein pathology that then extends via parasympathetic and sympathetic pathways to ultimately produce a body-first subtype. The resulting spread can be tracked by the development of symptoms, clinical assessments, in vivo imaging, and ultimately pathological examination. The integration of environmental exposures into the brain-first and body-first models generates testable hypotheses, including on the prevalence of the clinical conditions, their future incidence, imaging patterns, and pathological signatures. The proposed link, though, has limitations and leaves many questions unanswered, such as the role of the skin, the influence of the microbiome, and the effects of ongoing exposures. Despite these limitations, the interaction of exogenous factors with the nose and the gut may explain many of the mysteries of Parkinson's disease and open the door toward the ultimate goal -prevention.

Early and Late Transcriptomic and Metabolomic Responses of Rhododendron 'Xiaotaohong' Petals to Infection with Alternaria sp

In recent years, petal blight disease caused by pathogens has become increasingly epidemic in Rhododendron. Breeding disease-resistant rhododendron is considered to be a more environmentally friendly strategy than is the use of chemical reagents. In this study, we aimed to investigate the response mechanisms of rhododendron varieties to petal blight, using transcriptomics and metabolomics analyses. Specifically, we monitored changes in gene expression and metabolite accumulation in Rhododendron 'Xiaotaohong' petals infected with the Alternaria sp. strain (MR-9). The infection of MR-9 led to the development of petal blight and induced significant changes in gene transcription. Differentially expressed genes (DEGs) were predominantly enriched in the plant-pathogen interaction pathway. These DEGs were involved in carrying out stress responses, with genes associated with H2O2 production being up-regulated during the early and late stages of infection. Correspondingly, H2O2 accumulation was detected in the vicinity of the blight lesions. In addition, defense-related genes, including PR and FRK, exhibited significant up-regulated expression during the infection by MR-9. In the late stage of the infection, we also observed significant changes in differentially abundant metabolites (DAMs), including flavonoids, alkaloids, phenols, and terpenes. Notably, the levels of euscaphic acid, ganoderol A, (-)-cinchonidine, and theophylline in infected petals were 21.8, 8.5, 4.5, and 4.3 times higher, respectively, compared to the control. Our results suggest that H2O2, defense-related genes, and DAM accumulation are involved in the complex response mechanisms of Rhododendron 'Xiaotaohong' petals to MR-9 infection. These insights provide a deeper understanding of the pathogenesis of petal blight disease and may have practical implications for developing disease-resistant rhododendron varieties.

Herbicides in Water Sources: Communicating Potential Risks to the Population of Mangaung Metropolitan Municipality, South Africa

Pesticides are an important tool for maintaining and improving the global population's standard of living. However, their presence in water resources is concerning due to their potential consequences. Twelve water samples from rivers, dams/reservoirs, and treated drinking water were collected from Mangaung Metropolitan Municipality in South Africa. The collected samples were analysed using high-performance liquid chromatography linked to a QTRAP hybrid triple quadrupole ion trap mass spectrometer. The ecological and human health risks were assessed by risk quotient and human health risk assessment methods, respectively. Herbicides, such as atrazine, metolachlor, simazine and terbuthylazine, were analysed in water sources. The average concentrations of simazine in rivers (1.82 mg/L), dams/reservoirs (0.12 mg/L), and treated drinking water (0.03 mg/L) were remarkable among all four herbicides detected. Simazine, atrazine, and terbuthylazine posed high ecological risks for both acute and chronic toxicity in all water sources. Moreover, simazine is the only contaminant in the river water that poses a medium carcinogenic risk to adult. It can be concluded that the level of herbicide detected in water sources may affect aquatic life and human beings negatively. This study may aid in the development of pesticide pollution management and risk reduction strategies within the municipality.

The use of a simple model for the regulatory environmental risk assessment of pesticides in Ethiopia

Pesticide registration in developing countries like Ethiopia is often not supported by substantiated risk assessment procedures. In this study, we evaluated the PRIMET (Pesticide Risks in the Tropics for Man, Environment and Trade) Registration_Ethiopia_1.1 model which is a tool developed to assess the risks to non-target protection goals. All the 103 registered active ingredients (a.i.) in Ethiopia, except those used for flower and storage pest control purposes, were evaluated on their environmental risks. Data on physico-chemical characteristics, toxicity and pesticide use patterns were mined from either the information given in the dossier or public databases. Together with scenarios specifically developed for Ethiopia, these data were used to perform a risk assessment for the aquatic and terrestrial environment as well as for vertebrates including humans via contaminated drinking water exposure. Results indicated that 11 and 16% of the a.i.s are indicated to pose high acute risk and 7.3 and 11% high chronic risks for fish and aquatic invertebrates, respectively. Similarly, 5.5 and 8.7% high acute risks and 6.8 and 3.9% high chronic risks were observed for the soil ecosystem and birds, respectively. 23% of the evaluated active ingredients were indicated to be highly risky to bees when beehives are present inside the sprayed crop while 7.8% of them are highly risky when beehives are present outside the field of the sprayed crop. The fungicide metalaxyl, the herbicides acetochlor, alachlor, mecoprop and tembotrion, and the insecticides carbaryl, chlorpyrifos, diazinon and methidathion were predicted to pose high acute or chronic risks to humans or other vertebrates if surface water is used as a source of drinking water. Future studies should give emphasis on how the risk assessment results of this study can be implemented to aid the registration process.

Identifying unusual human exposures to pesticides: Qilu Lake Basin as an overlooked source

Although common exposure pathways of pesticides (e.g., crop consumption) have been intensively studied, we noticed that some unusual occupational exposures to pesticides were overlooked and could lead to unacceptable health risks. In this study, we presented information on the occurrence of 5 triazine pesticides (TRIs) and 3 neonicotine pesticides (NEOs) detected in water samples of Qilu Lake Basin in China. We identified the unusual occupational exposure scenarios as (i) adult females washing the harvested vegetables, and (ii) adult males catching fish in Qilu Lake; next, the health risk assessment was conducted using collected data. The results showed that the mean Σ5 TRI concentrations ranged from 505.87 ng/L in spring to 864.04 ng/L in summer, and the river water samples around Qilu Lake had the highest concentrations. The mean concentrations of Σ3 NEOs ranged from 885.86 ng/L in winter to 2593.04 ng/L in summer. Occupational exposed populations were bearing one to two orders of magnitude higher exposure doses than local adults. Although the carcinogenic risks caused by atrazine in water were at acceptable levels for local residents, all the occupational exposed males were at moderate risks, and 15.78 %-43.50 % of occupational exposed females in different seasons were even at high risks. The non-carcinogenic risks caused by pesticides in water were all at negligible levels, but the occupational exposed population were facing up to two orders of magnitude higher risks than local residents. This study established a sound basis for further decision-making to take necessary action on protection of sensitive population groups.

Seasonal drivers and risks of aquatic pesticide pollution in drought and post-drought conditions in three Mediterranean watersheds

The Western Cape in South Africa has a Mediterranean climate, which has in part led to an abundance of agriculturally productive land supporting the wheat, deciduous fruit, wine, and citrus industries. South Africa is the leading pesticide user in Sub-Saharan Africa. There is limited data on the pesticide pollution of surface water over different seasons in low- and middle-income countries. We evaluated the seasonal drivers of aquatic pesticide pollution in three river catchments (Berg, Krom, and Hex Rivers) from July 2017 to June 2018 and April to July 2019, using 48 passive samplers. Our sampling followed the most severe drought (2015-2018) since recordings in 1960. Thus, our analyses focus on how drought and post-drought conditions may affect in-stream pesticide concentrations and loads. Samples were analyzed for 101 pesticide compounds using liquid chromatography - high-resolution mass spectrometry. Environmental Quality Standards (EQS) were used to assess the risks. We detected 60 pesticide compounds across the sampling periods. Our results indicate that all samples across all three catchments contained at least three pesticides and that the majority (83%) contained five or more pesticides. Approximately half the number of pesticides were detected after the drought in 2018. High concentration sums of pesticides (>1 μg/L) were detected over long time periods in the Hex River Valley (22 weeks) and in Piketberg (four weeks). Terbuthylazine, imidacloprid, and metsulfuron-methyl were detected in the highest concentrations, making up most of the detected mass, and were frequently above EQS. The occurrence of some pesticides in water generally correlated with their application and rainfall events. However, those of imidacloprid and terbuthylazine did not, suggesting that non-rainfall-driven transport processes are important drivers of aquatic pesticide pollution. The implementation of specific, scientifically sound, mitigation measures against aquatic pesticide pollution would require comprehensive pesticide application data as well as a targeted study identifying sources and transport processes for environmentally persistent pesticides.

Collection of Data on Pesticides in Maize and Tomato in Africa: Protocol for Africa Pesticide Residue Survey Study

Pesticide use has grown rapidly in West Africa over the past decades. Regulatory capacity has not kept pace with the rapid proliferation of pesticide products and on-farm use. As a result, health and environmental impacts from the growing use of pesticides, despite their potential importance to food safety, remain largely unmonitored, underreported, and poorly understood by key stakeholders. This study protocol was the document for conducting a pesticide survey study to identify the most critically emerging pesticides across the Continent of Africa. Multiple countries were selected in this study to represent the north, east, south, and west regions of Africa. Two food commodities, maize and tomato, were chosen to monitor the pesticide level for food safety. This study protocol describes the fieldwork and laboratory work per the standards of Good Laboratory Practices (GLP) and ISO-17025 and US EPA 860 Residue Chemistry Guidelines but the survey study performed was not considered as a GLP or ISO 17025 study. This is because many steps were not able to be closely monitored per the GLP requirements. This protocol describes the requirements for a pesticide residue study in food collected from local markets. This protocol describes the test commodities, sampling methods, sample transfer/shipping, storage stability, sample analysis, sample disposal, and documentation and record keeping.

Agricultural pesticide use and misuse: A study to assess the cognizance and practices among North Indian farmers

Introduction

Farmers' cognizance regarding pesticide use and overuse is limited and their practices for handling of pesticides is unsatisfactory. However, their perception concerning risks and safety of pesticides play a very important role in safe spraying and indirectly protect them from adverse health hazards.

Objective

To assess the cognizance about use and risks of overuse of pesticides and evaluate practices for the storage, preparation, and disposal of pesticides.

Material and Methods

A cross-sectional study was conducted among 387 farmers of Lucknow who fulfilled the inclusion criteria. A multistage random sampling was done to interview the farmers. A pretested structured questionnaire was to collect the information regarding the cognizance about use and risks of overuse of pesticides and evaluate practices for the storage, preparation, and disposal of pesticides.

Results

More than half (55%) of the farmers did not read and follow the pesticide label. Maximum (80.2%) were unaware that pesticides are banned or restricted for use. Thirty-seven percent did not know that some pesticides may cause lethal intoxications. Majority of the farmers (42.6%) stored the pesticides anywhere in the house. More than two-thirds of the farmers (69.7%) mixed only needed pesticides followed by a low percentage of them applying on other crops (15.8%) and dispose in the field (11.7%).

Conclusion

The study concludes that cognizance and practices of the farmers for pesticide use and risks associated with it was not satisfactory and exposes them to adverse health outcomes.

Health Effects of Pesticide Exposure in Latin American and the Caribbean Populations: A Scoping Review

BACKGROUND

Multiple epidemiological studies have shown that exposure to pesticides is associated with adverse health outcomes. However, the literature on pesticide-related health effects in the Latin American and the Caribbean (LAC) region, an area of intensive agricultural and residential pesticide use, is sparse. We conducted a scoping review to describe the current state of research on the health effects of pesticide exposure in LAC populations with the goal of identifying knowledge gaps and research capacity building needs.

METHODS

We searched PubMed and SciELO for epidemiological studies on pesticide exposure and human health in LAC populations published between January 2007 and December 2021. We identified 233 publications from 16 countries that met our inclusion criteria and grouped them by health outcome (genotoxicity, neurobehavioral outcomes, placental outcomes and teratogenicity, cancer, thyroid function, reproductive outcomes, birth outcomes and child growth, and others).

RESULTS

Most published studies were conducted in Brazil (37%, n = 88 ) and Mexico (20%, n = 46 ), were cross-sectional in design (72%, n = 167 ), and focused on farmworkers (45%, n = 105 ) or children (21%, n = 48 ). The most frequently studied health effects included genotoxicity (24%, n = 62 ) and neurobehavioral outcomes (21%, n = 54 ), and organophosphate (OP) pesticides were the most frequently examined (26%, n = 81 ). Forty-seven percent (n = 112 ) of the studies relied only on indirect pesticide exposure assessment methods. Exposure to OP pesticides, carbamates, or to multiple pesticide classes was consistently associated with markers of genotoxicity and adverse neurobehavioral outcomes, particularly among children and farmworkers.

DISCUSSION

Our scoping review provides some evidence that exposure to pesticides may adversely impact the health of LAC populations, but methodological limitations and inconsistencies undermine the strength of the conclusions. It is critical to increase capacity building, integrate research initiatives, and conduct more rigorous epidemiological studies in the region to address these limitations, better inform public health surveillance systems, and maximize the impact of research on public policies. https://doi.org/10.1289/EHP9934.

Interventions to Reduce Pesticide Exposure from the Agricultural Sector in Africa: A Workshop Report

Despite the fact that several cases of unsafe pesticide use among farmers in different parts of Africa have been documented, there is limited evidence regarding which specific interventions are effective in reducing pesticide exposure and associated risks to human health and ecology. The overall goal of the African Pesticide Intervention Project (APsent) study is to better understand ongoing research and public health activities related to interventions in Africa through the implementation of suitable target-specific situations or use contexts. A systematic review of the scientific literature on pesticide intervention studies with a focus on Africa was conducted. This was followed by a qualitative survey among stakeholders involved in pesticide research or management in the African region to learn about barriers to and promoters of successful interventions. The project was concluded with an international workshop in November 2021, where a broad range of topics relevant to occupational and environmental health risks were discussed such as acute poisoning, street pesticides, switching to alternatives, or disposal of empty pesticide containers. Key areas of improvement identified were training on pesticide usage techniques, research on the effectiveness of interventions targeted at exposure reduction and/or behavioral changes, awareness raising, implementation of adequate policies, and enforcement of regulations and processes.

Seasonal Changes in Pesticide Residues in Water and Sediments from River Tano, Ghana

Pollution due to pesticide residues has been reported in the downstream of the Tano Basin in the rainy season and has been attributed to the anthropogenic activities upstream. However, data on the seasonal variations in pesticide residues in the upstream of Tano Basin are limited. Seasonal variations in 13 organochlorine pesticide residues, 8 organophosphorus pesticide residues, and 5 synthetic pesticide residues in water and sediment samples of River Tano upstream were assessed through extraction and Varian CP-3800 gas chromatography equipped with a CombiPAL Auto sampler set at ionization mode electron impact methods. Significantly higher pesticide residues were detected in water and sediment samples in the rainy season than the dry season. Permethrin (rainy: 0.007 ± 0.01 mg/kg; dry: 0.008 ± 0.02 mg/kg) and profenofos (rainy: 0.021 ± 0.02 mg/kg; dry: 0.026 ± 0.01 mg/kg) showed higher dry season concentrations in the sediment samples. Two isomers of lindane (δ-HCH = 0.059 ± 0.24 μg/L; γ-HCH = 0.002 ± 0.01 μg/L) were detected in the water in the rainy season, but 3 were detected in the sediment samples (δ-HCH = 0.004 ± 0.12 mg/kg; γ-HCH = 0.003 ± 0.01 mg/kg; aldrin = 0.001 ± 0.01 mg/kg) suggesting possible illegal use. The detected pesticide residual levels in both water and sediment samples were lower than the maximum residual levels in water and sediment. The Chemical Control and Management Centre of the Environmental Protection Agency should check possible faking and adulteration of banned organochlorine pesticides.