Pesticide use in Bangladesh: farmers perceptions, and implications for soil health and foodsafety

Worldwide, expanded pesticide use has reduced crop losses and boosted agricultural productivity by controlling insects, pathogens, and weeds. However, these gains have raised concerns about food safety, environmental contamination, and human health. Misuse, overapplication, and weak regulation intensify these risks, especially in developing countries with limited monitoring. In Bangladesh, pesticide use has risen sharply in intensive vegetable farming. Economic pressure drives frequent spraying beyond recommended doses. Although farmers are generally aware of hazards, safety measures during handling and storage are often neglected, leading to soil degradation, contaminated produce, and health risks for farmers and consumers.This thesis investigates three interconnected dimensions of pesticide use and environmental risk in vegetable farming systems in northern Bangladesh. First, it examines farmers’ knowledge, attitudes, and practices regarding insecticide use and associated health implications. The findings reveal that education level, age, farming experience, and access to training significantly influence protective behaviours. Younger and better-educated farmers are more likely to follow safety guidelines, whereas older farmers—who often dominate rural agriculture due to youth migration—tend to rely on habitual practices and peer advice. Unsafe behaviours such as mixing pesticides by hand, storing chemicals inside homes, and discarding empty containers in open fields remain common. Despite awareness of potential health and environmental impacts, over-application persists, particularly in high-value crops such as eggplant, chilli, and tomato. The results highlight a critical gap between awareness and implementation, underscoring the need for participatory, community-based training and improved risk communication strategies.Second, the thesis evaluates the persistence and movement of obsolete organochlorine insecticides in the terrestrial food chain. Although banned decades ago, residues of compounds such as DDT, HCHs, aldrin, endosulfan, chlordane, heptachlor, chlordecone, mirex, and hexachlorobenzene were detected in soil, vegetables, and cow’s milk. Subsoil often contained higher concentrations than surface soils, indicating long-term persistence and limited degradation. While most detected levels were below international Maximum Residue Limits, the co-occurrence of multiple residues in single food items raises concerns regarding cumulative exposure. Potential contamination sources include historical use, and illegal marketing of banned pesticides. These findings emphasize the importance of regular residue monitoring, strict enforcement of regulations, and comprehensive risk assessments that consider chronic low-dose exposure.Third, the ecological component investigates the impacts of widely used insecticides cypermethrin, imidacloprid, and chlorantraniliprole on non-target soil biota, the anecic earthworm Lumbricus terrestris. Experimental findings demonstrate that earthworm activity plays a critical role in regulating pesticide mobility within soil profiles. Imidacloprid exhibited the highest toxicity and mobility, while insecticide mixtures significantly enhanced vertical biogenic transport through burrow networks. Pesticide residues were consistently higher in burrow linings than in adjacent bulk soil, especially at depths of 15–30 cm, confirming that earthworm-mediated biogenic transport can facilitate deeper soil contamination, a pathway often underestimated in conventional leaching models.Overall, this study reveals the complex interplay between farmer behaviour, chemical persistence, and ecological processes in shaping pesticide-related risks. It calls for integrated governance approaches combining farmer education, regulatory strengthening, ecological risk assessment, and sustainable agricultural practices to safeguard environmental and public health in Bangladesh.