HEAVY METAL CONCENTRATIONS AND HEALTH RISK ASSESSMENT OF A RURAL MULTIPURPOSE STREAM, SOUTHEAST NIGERIA

Abstract

The heavy metal concentrations of a rural multipurpose stream in South-east Nigeria were evaluated between May 2021 and October 2021 in 3 stations. The non-carcinogenic health risk assessment was used to check the water’s suitability for human consumption, swimming and wadding. Eight heavy metals were assessed using standard methods and the Nigerian Drinking Water Quality Standard was used as standard. The concentrations were zinc (0.07 - 0.52 mg/l), copper (0.04 – 0.19 mg/l), manganese (0.04 - 0.31 mg/l), lead (0.01 - 0.09 mg/l), nickel (0.01 - 0.05 mg/l), chromium (0.02 - 0.11 mg/l), iron (0.10 and 0.91 mg/l) and cadmium (0.01 and 0.07 mg/l). Some metals (manganese, lead, iron, cadmium, nickel and chromium) exceeded acceptable limits. The hazard indices (HI) for oral exposure was 3.34 – 3.96 (adult) and 4.29 – 5.69 (children) while for dermal exposure, it was 0.96 – 1.10 (Adult) and 0.93 – 1.17 (children). The HI values were higher than 1 except for HIdermal (adult and children) in station 3. The heavy metal concentrations and health risk assessment has shown that the water from this multipurpose rural stream was not fit for human consumption, swimming or wadding. This conclusion was based on the high concentrations of manganese, lead, iron, cadmium, nickel and chromium, which exceeded limits but cadmium was responsible for the adverse health risk observed. The children were more susceptible. The health risk involved in consuming water from this stream was high in all the stations and should be discouraged. On the other hand, there was a moderate health risk for swimming and wadding in stations 1 and 2 and none in station 3 which was considered negligible. Geogenic influence was a major factor but was influenced by season and anthropogenic activities (especially agriculture) in the stream.

Keywords

• limits
• heavy metal
• water quality
• drinking water
• agriculture
• swimming