ESTIMATION OF HUMAN HEALTH RISK FROM EXPOSURE TO METHYLMERCURY VIA FISH CONSUMPTION IN GHANA

Abstract

Background. Fish advisories have been established by some nations to protect the public from the potentially harmful health effects linked to eating contaminated fish. Advisories are based on estimations of the health risks associated with concentrations of contaminating chemicals found in fish, and the average levels of consumption of fish in the population. Fish is an important source of nutrition in Ghana; however, little is known about the possible health effects associated with metal concentrations found in fish. Objective. The overall aim of the present study was to estimate metal concentrations in fishery resources so as to inform guidelines on fish consumption. Methods. We collated previously published data on levels of metals in fish in Ghana. We also estimated the potential for adverse health effects by calculating a hazard quotient (HQ) based on the reported levels of mercury in fish and either the United States Environmental Protection Agency (USEPA) Reference Dose (RfD) or the FAO/WHO Expert Committee on Food Additives Provisional Tolerable Weekly Intake (PTWI). Both are estimates of methylmercury exposure that is considered safe (0.0001 mg/kg body weight (bw) per day and 0.0016 mg/kg bw/week, respectively). We also compared HQ estimates across different fish species and water bodies in Ghana. Results. Mercury was the only metal for which there was sufficient data to estimate the possible adverse health effects from eating fish caught in Ghana. The mean concentration of mercury was 0.10 mg/kg (± 0.15) wet weight (N= 63 fish samples). This concentration was associated with a HQ of less than 1 when using the Joint FAO/WHO PTWI, but above 1 when using the USEPA RfD. Higher concentrations of mercury (Hg) were detected in fish collected from rivers in gold mining areas of Ghana (0.25 mg/kg ww ±0.23) versus fish collected from lakes/reservoirs (0.04 mg/kg w.w ±0.04) and marine areas (0.06 mg/kg w.w ±0.04). Conclusions. These results suggest regular monitoring of fish collected from water bodies in gold mining regions is warranted. Results also suggest that regulatory bodies may want to consider the development of guidelines for fish consumption advisories when warranted, and remediation of primary sources of mercury contamination to optimize the health benefits of fish consumption. Competing Interests. The authors declare no competing financial interests. Keywords. heavy metals, Ghana, risk assessment, methylmercury, fish, seafood safety, mercury database, hazard quotient J Health Pollution 6: 18-25 (2014)