Human health risk characterization of lead pollution in contaminated farmlands of Abare village, Zamfara State, Nigeria

Abstract

This study was initiated to assess the level of lead (Pb) contamination in farmlands, crop plants and water sources and the health risk in one of the Pb-contaminated villages of Zamfara State. Soil samples were collected from two depths at intervals of 10, 50, 150, 300, 500 and 1000 m from the last house along each of the four cardinal directions (North, South, East and West). Crop plant samples were also collected at each sampling distance while profile pits were dug at 150 m in each direction. Water samples were collected from all available sources in the villages. Contents of total Pb was determined in all samples following aqua regia digestion for soil and plant samples, water samples were digested with HNO₃. Health risk assessment was based on lifetime exposure through ingestion and inhalation of soil and dust based on the USEPA risk exposure models. The average concentrations of Pb in farmlands (515 mg kg^-1) and profile pits (365 mg kg^-1) were lower than its extent in plant materials (1220 mg kg^-1). The average chronic daily intake (CDI) for carcinogenic risk in mg kg^-1 day^-1 was 1.3 x 10⁵ for Pb. Non carcinogenic CDI in mg kg^-1 day^-1 averaged 1.7 x 10⁸ in adults. For children, it averaged 9.7 x 10⁷ mg kg^-1 day^-1. However, the concentrations in all the samples are far beyond acceptable levels with high repercussion for environment and human health hazard. Suitable intervention measures are required to reduce these high concentrations in order to minimize risks associated with contamination.

Key words: Heavy metals, lead, Zamfara, health risk, soil contamination.