Bioaccumulation and non-carcinogenic health risk assessment of heavy metals in selected fish species from South Bay of Laguna Lake

Objective@#The study aimed to determine the concentration of three heavy metals namely, lead (Pb), cadmium (Cd) and chromium (Cr) present in head, stomach and muscle parts of Nile Tilapia (Oreochromis niloticu) and Blackchin Tilapia (Sarotherodon melanotheron) collected from different sampling sites in South Bay area of Laguna Lake and evaluate its potential health risk for adult consumers. @*Methods@#Live samples of Nile Tilapia and Blackchin Tilapia were hand-collected from three sites of South Bay of Laguna Lake during wet season. Raw and boiled samples were prepared for analysis. Heavy metal concentrations (mg kg-1) were determined through flame atomic absorption spectrophotometry (AAS). The potential health risk posed by more than one metal was calculated using the Total Hazard Quotient (THQ). @*Results@#The heavy metal detected with the highest concentration was Pb, present in Nile Tilapia. The mean concentrations of Pb, Cd, and Cr in both fish samples were high in the head part. Boiled samples have significantly lower concentrations of heavy metal (p<0.05) compared to raw samples. THQ values for Cd in raw fish samples were higher than the recommended level of exposure (THQ < 1.0). @*Conclusion@#The study revealed that cadmium is of greater concern in terms of possible adverse health effects associated with heavy metal bioaccumulation. However, the presence of other metals may further increase the risk of non-carcinogenic adverse effects. The lower health risk is predicted for boiled fish samples.

Risk and Toxicity Assessments of Heavy Metals in Tympanotonus fuscatus and Sediments from Iko River, Akwa Ibom State, Nigeria

This study evaluates the physico-chemical parameters and heavy metals in water, sediments and Tympanotonus fuscatus obtained from three sample sites along Iko River in Eastern Obolo LGA, AkwaIbom State. The heavy metal analysis results on Pb, Cd and Ni in sediments and Tympanotonus fuscatus were used to estimate the human health and ecological risk assessment of the study area. The human health risk assessment tools utilized in this study were estimated dietary intake (EDI), total hazard quotient (THQ) and hazard index (HI) while sediment pollution parameters evaluated were contamination factor (CF), contamination degree (CD), pollution load index (PLI) and geoaccumulation index (Igeo). Results obtained showed that EDI of Cd in periwinkle in the study sites ranged from 0.2 – 6.4 µg/kg-bw/day and exceeded the provisional tolerable dietary intake (PTDI), while EDI for Pb (0.0004 – 2.6 µg/kg-bw/day) and Ni (0.32 – 2 µg/kg-bw/day) was within the limit for all sites, except Ni in site II (34 µg/kg-bw/day) which was higher than the PTDI of 5 µg/kg-bw/day. The THQ of Cd in all sites was greater than 1, while Pb and Ni generally recorded THQ < 1. The hazard index (HI) was as follows: site I (2.36), sites II (24.44) and site III (6.5), highlighting a potential hazardous effect to humans as a result of the consumption of Tympanotonus fuscatus obtained from site II and III. The sediment pollution assessment revealed that the contamination factor (CF) and geoaccumulation index, Igeo of Cd were far above the permissible limits while Pb and Ni were mostly within limits. The estimated contamination degree (CD) and pollution load index (PLI) showed a high degree of pollution, which can be mainly attributed to the high degree of Cd contamination in the sediment. Therefore, the area under investigation is highly polluted and the periwinkle obtained from Iko river in the study area is unfit for human consumption.