Pesticides are used globally in agriculture and pose a threat to the health of farmers, communities, and the environment. Smallholder farmers in low- and middle-income countries have generally a low socio-economic status and educational level. Consequently, they are particularly vulnerable to negative impacts of pesticides on their health, yields, or land. In a Knowledge, Attitude, and Practices study, we compared the pest management practices between a market-oriented farming system in Zarcero County, Costa Rica, and a subsistence-based farming system in Wakiso District, Uganda. We conducted a cross-sectional survey among smallholder farmers from Costa Rica (n = 300) in 2016 and from Uganda (n = 302) in 2017. We enrolled conventional and organic farmers, but also farmers with mixed practices and non-applicators of any pest management strategy. We found that the majority of pesticides used in both case studies are classified as highly hazardous by the World Health Organization. While more than 90% of smallholder farmers from both countries were aware of the negative health effects of pesticide exposure, <11% in Costa Rica and <2% in Uganda reported using personal protective equipment every time they handled or applied pesticides. Hygiene and other safe use practices were not adopted by all farmers (<61%), especially among farmers applying more hazardous pesticides. Conventional farmers from Costa Rica (14%) and Uganda (19%) reported disposing pesticide residuals into rivers. Using a logistic regression we found that organic farmers were more likely to having been trained on safe pesticide use practices. Using a robust regression, we observed that smallholder household income was primarily driven by education and not directly by the use of synthetic pesticides. Our results suggest that negative effects of pesticides can be managed over the whole life cycle, from purchase, via storage and application to residual and waste management by fostering professionalization of farmers. We advise future safe use and handling interventions to consider the pesticide use-related socioeconomic and demographic findings highlighted in this paper.

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Pesticide misuse by farmers poses health risks to consumers. This study assessed the level of dithiocarbamate residues in tomatoes acquired from 20 farmers and 25 market vendors in Wakiso District, how simple washing affects these residues, and the potential chronic health risk for Ugandans eating such tomatoes. Results revealed that mancozeb was the only reported dithiocarbamate, and 47.4% and 14% of farm and market samples, respectively, had dithiocarbamate residues exceeding the Codex alimentarius maximum residue limit of 2 mgCS2/kg. Mixing concentration had a positive significant effect on dithiocarbamate residue levels (P = 0.004). Washing reduced dithiocarbamate residues by a factor of 0.3. Dietary risk assessment revealed no chronic health risk to both children and general population when a national daily per capita consumption of 1.0 g is considered. This study recommends comprehensive research into Uganda’s food production and consumption patterns and establishment of a national pesticide residue surveillance program.

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On the African continent, ongoing agriculture intensification is accompanied by the increasing use of pesticides, associated with environmental and public health concerns. Using a systematic literature review, we aimed to map current geographical research hotspots and gaps around environmental and public health risks research of agriculture pesticides in Sub-Saharan Africa (SSA). Studies were included that collected primary data on past and current-used agricultural pesticides and assessed their environmental occurrence, related knowledge, attitude and practice, human exposure, and environmental or public health risks between 2006 and 2021. We identified 391 articles covering 469 study sites in 37 countries in SSA. Five geographical research hotspots were identified: two in South Africa, two in East Africa, and one in West Africa. Despite its ban for agricultural use, organochlorine was the most studied pesticide group (60%; 86% of studies included DDT). Current-used pesticides in agriculture were studied in 54% of the study sites (including insecticides (92%), herbicides (44%), and fungicides (35%)). Environmental samples were collected in 67% of the studies (e.g., water, aquatic species, sediment, agricultural produce, and air). In 38% of the studies, human subjects were investigated. Only few studies had a longitudinal design or assessed pesticide’s environmental risks; human biomarkers; dose-response in human subjects, including children and women; and interventions to reduce pesticide exposure. We established a research database that can help stakeholders to address research gaps, foster research collaboration between environmental and health dimensions, and work towards sustainable and safe agriculture systems in SSA.