Multivariate analysis and dietary risk assessment of dieldrin in Nigerian staple crops and cooking wastewater

Dieldrin is a persistent organochlorine pesticide that remains in food chains despite global restrictions. This study assessed its occurrence, thermal stability, and associated health risks in eighteen commonly consumed grains and legumes (local rice, foreign rice, yellow corn, white corn, red guinea corn, white guinea corn, pearl millet, finger millet, red soft wheat, white soft wheat, white hard wheat, white iron beans, oloka beans, brown beans, white soya beans, red soya beans, red pigeon pea, and white pigeon pea) obtained from markets in Awka, Nigeria. Samples ( n = 162) were subjected to domestic processing conditions: washing at 25 °C, heating at 50 °C for 15 min, and boiling at 100 °C for 10 min. Residues were extracted using a modified QuEChERS method and quantified by GC–MS under strict quality assurance protocols. Dieldrin concentrations frequently exceeded the FAO/WHO maximum residue limit (0.01 mg kg − 1) in approximately 66.6% of all food crop samples across all treatment conditions. Thermal processing produced only marginal reductions, confirming the compound’s high thermal stability. Notably, elevated concentrations persisted in wheat (white soft and hard), local rice, yellow corn, and selected beans. Thermal treatment did not significantly affect dieldrin concentrations in wastewater, and the observed variations across temperatures are likely minor fluctuations. Health risk assessment based on estimated daily intake and hazard index (HI) revealed values exceeding unity (HI > 1) for local rice and yellow corn, indicating non-carcinogenic risk to consumers. These findings suggest that routine cooking practices are insufficient to mitigate dieldrin exposure. The persistence of dieldrin in thermally processed foods highlights a critical food safety concern, underscoring the need for stricter monitoring, improved agricultural practices, and regulatory enforcement in affected regions.