Pesticide use trends (2000–2026), exposure pathways, human health risks, environmental contamination, and policy challenges in Tanzania

The rapid agriculture intensification in Tanzania has substantially increased pesticide use, posing growing threats to food safety, environmental quality, and public health. Although numerous studies have investigated pesticide use and its impacts, there is limited comprehensive synthesis on systematic evaluation of national pesticide use trends over the past 25 years. This study synthesized evidence on pesticide use, exposure pathways, environmental contamination, health effects, regulatory frameworks, and management strategies in Tanzania between 2000 and 2026 using publicly available data sources. Secondary data were collected from published literatures from PubMed/MEDLINE, Scopus, Web of Science, Google Scholar, FAOSTAT, and grey literature sources. About 78 studies were included, including cross-sectional surveys (43.6%), residue-monitoring studies (23.1%), longitudinal studies (15.4%), reviews (11.5%), and policy analyses (6.4%). Over the 25 years period, pesticide use increased markedly with horticultural expansion, irrigation, and commercialization. Organophosphates dominated pesticide use (approximately 97%, single-study estimate), carbamates (approximately 56%, single-study estimate) and substituted benzenes (approximately 36%, single-study estimate), while more than 60 pesticide products representing 14 chemical classes were documented. Approximately 58% of farmers reported increasing pesticide use, 71.2-93.7% routinely mixed multiple pesticides, only approximately 48% applied pesticides correctly (single-study estimate), and approximately 89% lacked adequate knowledge of safe pesticide handling. More than 90% of applicators do not use personal protective equipment. Residue monitoring revealed detectable pesticides in approximately 48% of vegetable samples (single multi-site study), with approximately 74% exceeding Codex Maximum Residue Limits; banned organochlorines, including DDT metabolites and endosulfan, persisted in vegetables, soils, water, fish, and poultry products. Acute pesticide poisoning affected approximately 48% of cotton farmers in one cross-sectional study and approximately 68% of vegetable farmers in another, while approximately 27% of applicators exhibited depressed acetylcholinesterase activity, indicating chronic organophosphate exposure. Because these figures are drawn from individual studies with heterogeneous designs, populations, and sample sizes rather than from pooled meta-analytic estimates, they are reported as approximate magnitudes rather than precise point values. Weak regulatory enforcement, unsafe disposal practices, and obsolete pesticide stockpiles further exacerbated contamination risks. Strengthening pesticide regulation, residue surveillance, Integrated Pest Management adoption, farmer training, and poisoning surveillance is essential to safeguard human health, food security, and environmental sustainability in Tanzania.