Comparative evaluation of trace element and metalloid exposure and dietary health risks associated with Katsuwonus pelamis and Clarias macrocephalus in Ghana

Trace metal pollution in aquatic environments presents growing concerns for public well-being, especially in developing countries such as Ghana. This study quantified the concentrations of lead (Pb), cadmium (Cd), arsenic (As), and mercury (Hg) in two frequently consumed fish varieties (25 specimens), skipjack tuna ( Katsuwonus pelamis-Linnaeus,1758), and catfish ( Clarias macrocephalus-Günther,1864 ), and evaluated the associated dietary health risk. Twenty-five samples of each species (n = 25) were picked from Madina market , a major distribution centre, and analyzed using inductively coupled plasma-mass spectrometry (ICP-MS) following microwave-assisted digestion. The method's accuracy was confirmed using certified reference material (DORM‑4), yielding recoveries ranging from 94.6% to 109.2%. The average concentrations (mg/kg wet weight) observed in K. pelamis were 0.533 for Pb, 0.011 for Cd, 1.000 for As, and 0.138 for Hg. In contrast, C. macrocephalus exhibited concentrations of 0.034 for Pb, 0.254 for Cd, 0.219 for As, and 0.046 for Hg. Notably, the concentrations of Pb in K. pelamis and Cd in C. macrocephalus surpassed the maximum permissible limits established by the FAO/WHO Codex Alimentarius . Furthermore, independent-samples t-tests indicated significant differences between species for all metals (p < 0.001), with effect sizes ranging from large to very large (Cohen’s d = 1.9–19.1), underscoring distinct bioaccumulation patterns specific to each species. The assessment of dietary exposure was conducted using estimated daily intake (EDI), target hazard quotient (THQ), and cumulative hazard index (HI). For the majority of trace metals, individual THQs remained below one; however, the THQ for Hg in K. pelamis was 0.985, and for inorganic As in C. macrocephalus , it was 0.794, suggesting a borderline non-carcinogenic risk that deserves attention, particularly for vulnerable populations . These results underscore the urgent need for ongoing surveillance, the integration of metal speciation analyses, and the formulation of risk-based fish consumption advisories to safeguard public health in Ghana.