CONCENTRATIONS AND HEALTH RISK ASSESSMENT OF HEAVY METALS IN WATER, SEDIMENT, AND FISH SPECIES FROM OSE RIVER, ONDO STATE, NIGERIA

Abstract

Indiscriminate discharge of untreated sewage, effluent and agricultural runoff in most developing countries had been a
major problem that has led to increase in deposition of heavy metal in the aquatic system especially the essential metals at a
level higher than most of the non-essential ones. Concentrations of chromium (Cr), iron (Fe), nickel (Ni) and zinc (Zn) were
investigated in water, sediments and fish of Ose River, Ondo State, Nigeria to determine the potential health risk associated
with consumption of fish from the river. A total of 116 fishes were collected between June and November (2019) and
analyzed for heavy metal using Atomic Absorption Spectrophotometer. Results show high concentrations of these metals
above tolerable limits set by Nigeria Industrial Standards (NIS) and World Health Organization/Federal Environmental
Protection Agency for water and sediment respectively except for Ni. The Concentrations of Cr in examined organs (Gill,
muscle and liver) exceeded WHO consumption safety limits of 0.15mg/kg. Concentrations of Ni and Zn in all the organs
also exceeded permissible limits except the gill and liver of Heterbranchus longifilis respectively. Fe was the only metal
below safe limit except in liver of all the fish samples. A positive correlation was seen between metals' concentration in the
sediment and fish species. The human health risk assessments show that all Estimated Daily Intake values were lower than
Recommended Dietary Allowance except for Cr among fishers. Target Risk and Hazard Index values reveal high risk of
both carcinogenic and non-carcinogenic effect respectively, for both the general public and fishers.