Carcinogenic and Non-Carcinogenic Health Risk Assessment of Heavy Metal Exposure at a Battery Recycling Site in Ogijo South West, Nigeria

Although recycling of batteries is economical and environmentally friendly, occupational and environmental heavy metal pollution is dangerous because of the health-threatening effects. This paper evaluated both carcinogenic and non-carcinogenic health risks caused by the exposure to heavy metal in a battery recycling plant in Nigeria in Ogun State, Ogijo. The analysis of nine heavy metals (Pb, Cd, Cr, Ni, Fe, Mn, Co, Zn, Cu) in water samples collected in wet and dry seasons was performed by the use of flame atomic absorption spectrophotometry. Chronic daily intake (CDI) was determined to ingestion and dermal exposure routes with risk being described by quotients of hazards (HQ) and hazard indices (HI) and incremental lifetime cancer risk (ILCR). Non-carcinogenic risk assessment gave an average hazard index of 0.014 (ingestion) and 0.00008 (dermal), which are less than the USEPA limit of 1.0, and this implies acceptable non-cancer risk levels. But the assessment of carcinogenic risks showed collective ILCR of 3.12 × 10-4, which is above the acceptable limit (1 × 10-6 to 1 x 10-4). Lead and chromium were the greatest contributors to cancer risk (Pb: 1.54 × 10-4 wet season; Cr: 4.3 × 10-4 wet season). Dermal exposure was less risky as compared to ingestion pathways. Seasonal variation was found to have high levels of contaminants in wet season, which was due to industrial runoff. This paper explains why site remediation should be increased, occupational health standards should become more stringent, and regulation should be enforced to curb the exposure of heavy metals to the workers and neighbors.