Heavy Metals and Polycyclic Aromatic Hydrocarbons in Commonly Consumed Crayfish in Nigeria and Health Risk Implications

Heavy metals and polycyclic aromatic hydrocarbons (PAHs) are common environmental pollutants. Its increased presence in the aquatic environment has raised serious concerns about its effect on aquatic life and by extension, a man who is at the apex of the food chain. This research investigated the concentrations of selected heavy metals (Lead, Nickel, Cadmium and Chromium) and PAHs in two species of commonly consumed crayfish in Nigeria and their health risk implications. Wet digestion procedure and atomic absorption spectrometry were used for heavy metal determination while the United States environmental protection agency (USEPA) test method for evaluation of solid waste was used for PAHs analysis. Results showed that Pb, Ni and Cd in both species of crayfish were above tolerable limits. The mean level for Ni in Litopenaeus setiferus was 3.0630.116mg/kg and 5.1571.676mg/kg in Litopenaeus stylirostris. The mean value for Cd in L. setiferus was 0.8330.070 mg/kg and 0.6000.025 mg/kg for L.stylirostris. The mean value for Pb in L. setiferus was 4.5500.656mg/kg and 3.6430.486 mg/kg in L. stylirostris. Mean values for Cr in L. setiferus was 0.0870.082 mg/kg and 0.000 mg/kg in L. stylirostris. Mean PAHs concentrations in L. setiferus and L. stylirostris were 0.0036±0.002 ppm and 0.0083±0.004 ppm respectively. Health risk assessment revealed an increasing health risk due to the consumption of both species of crayfish. Results for PAHs in both species of crayfish showed compliance with set limits. Its presence in fish food however suggests possible health concerns especially with regards to their carcinogenic tendencies. Anthropogenic activities should be closely monitored as bioaccumulation along the food chain is implicated.