Trace Metal Contamination in Tropical Endemic Fish: Factorial Effect Interactions and In situ Quantitative Risk Assessment

Abstract

Aim: Contamination of the Anambra River with heavy metals (arsenic, As; cadmium, Cd; chromium, Cr; copper, Cu; lead, Pb; nickel, Ni; and zinc, Zn) was examined in two preponderant fish species (Synodontis clarias and Tilapia nilotica) following earlier detection of the elements in water column. Methods: Levels of heavy metals were measured in both seasonal regimes (rainy and dry) at five selected locations with atomic absorption spectrophotometer. Factorial effects and interactions were explored on completely randomized block design. Quantitative risk of metal exposure through contaminated fish consumptions among the resident community population at the river was assessed to extrapolate the probable public health threat. Results: The result showed variations among heavy metal concentrations in fish and Zn and Cu recorded significant amounts with S. clarias recording higher concentrations than T. nilotica. Season, species of fish and location and their interactions had significant effects on the amounts of Cu and Zn accumulated in the fish tissues except season by species effect. Zinc recorded the highest concentrations at all locations measured, with Onono (location 5) producing the fish species with the highest amount of metals compared with other locations. The heavy metal concentrations were below the comparable international safe standards. Margin of exposure and exposure dose calculated for the heavy metals were all below reference standards and tentatively considered not to be of risk to public health. Conclusion: However, there is considerable concern of contamination of the fish species with heavy metals and recommended regular monitoring or examination of edible fish species.

Microbial diversity, heavy metals and hydrocarbons concentration in some fish species from Qua Iboe River Estuary, Akwa Ibom State, Nigeria

“…Furthermore, some other aquatic animals may have accumulated these chemicals in their bodies from other habitats, and have overtime migrated to the water body sampled in this study. The concentration of PAHs and BTEX recorded in this work is similar to those reported by other researchers [50,51]. In their study, Akinsanya et al [52] reported a concentration of 49.86±7.30 μg/L and 173.34±4.677 μg/g for BTEX and PAHs respectively as they bioaccumulate in the intestine of Heterotis niloticus.…”

Noncarcinogenic risk assessment of ten heavy metals in nine freshwater species sourced from market-ready landing sites

“…Target hazard quotient (THQ) used to characterise oral metal exposure and chronic noncarcinogenic risk was conducted following established methods and assumptions [2,7,[20][21][22][23][24][25]: MC = metal mean concentration (mg kg −1 ), IR = the daily ingestion rate (adult) (0.04 kg), EF = the exposure frequency (365 days/year), ED = the exposure duration for noncarcinogens (…”

“…There has been a growing community concern among residents within riverine areas of Anambra State Nigeria about the potential contamination of freshwater ecosystems that hold critical livelihood economics of the community through fish trade. A body of empirical research in River Niger and Anambra River, the largest freshwater ecosystems in the state, has shown the degree to which the systems are contaminated with appreciable metal concentrations that potentially pose public health risks to freshwater food consumers [1][2][3][4][5]. The river sites studied represent zones of unregulated waste disposal and human activities that threaten ecology of those freshwater systems.…”

Risk assessment of heavy metals in water and sediments in the Mara river and its tributaries

“…According to literature, fish's position in the trophic transfer of heavy metals through the aquatic food chain and food menu (Fig. 1) poses a higher risk to public health (Levit, 2010;Obiakor et al, 2015).…”