Human health risk from dietary exposure to heavy metals through poultry eggs: Evidence from commercial farms in Wakiso District, Uganda

Abstract

• Elevated Cr, As, Cd found in eggs from Kajansi and Katabi areas. • Weekly metal intake via eggs is below global safety limits. • Significant intake differences linked to feed and environment. • ICP-MS data from 53 farms informs food safety strategy. • First Ugandan study linking feed contamination to human exposure. Uganda’s projected annual egg consumption of 1.9 kg per capita by 2025 raises concerns over heavy metal contamination in poultry products. Wakiso District, a peri‑urban hub supplying Kampala, faces potential exposure risks due to inconsistent feed quality. This study sampled 53 poultry farms in Wakiso District. Egg and feed samples were analyzed for chromium (Cr), lead (Pb), mercury (Hg), arsenic (As), and cadmium (Cd) using ICP-MS. Weekly intake estimates were derived from FAO consumption data and compared against WHO/JECFA and Codex thresholds. Spatial variation was assessed using the Kruskal–Wallis H test. Cr levels peaked at 6.72 ± 4.91 mg/kg in Kajansi, with intake of 237.6 μg/week, below the JECFA limit of 2100 μg. As reached 1.36 ± 0.48 mg/kg, with intake up to 42.3 μg/week, under the WHO threshold of 1050 μg. Cd exposure peaked at 0.15 ± 0.10 mg/kg, translating to 2.69 μg/week, below the FAO limit of 2695 μg. Significant spatial differences were observed for Cr (H = 41.77), As (H = 49.82), and Cd (H = 31.94), all p < 0.001. While overall intake remains within safety limits, localized contamination in Kajansi and Katabi suggests cumulative risk, hence need for regulations and feed and residue monitoring.