Heavy metal concentration in the muscle tissues of selected commercially important fishes and health risk assessment in Tubay, Agusan del Norte, Philippines

Caraga Region is a hub for nickel-iron mining operations in Tubay, Agusan del Norte. Two notable mining companies are currently operating—San Roque Metal Inc. (SRMI) and Agata Mining Venture Inc. (AMVI). Three heavy metals, namely mercury (Hg), lead (Pb), and chromium (Cr), were analyzed from the muscle tissues of commercially important fishes, and a health risk assessment for human consumers was conducted. Heavy metal concentrations were determined using cold vapor atomic absorption spectrometry (AAS) for Hg and Flame AAS for Pb and Cr. Levels of heavy metals at various stations fall within FAO s approved maximum permitted limits, except for Cheilinus trilobatus, which exhibits elevated levels of Pb with a concentration of 6.21 mg/kg fresh weight in Lawigan. The highest fish consumption was observed in Binuangan (2.70 g/person/day), while the lowest was in La Fraternidad (1.15 g/person/day). Health risk indicators for environmental risk assessment revealed potential risk values surpassing the reference dose. The estimated daily intake (EWI) surpassed acceptable levels in C. trilobatus, while the Target Hazard Quotient (THQ) for Cr and the Total THQ exceeded one for most fish species.These findings underscore the critical need for ongoing research to thoroughly investigate and monitor fishery commodities, including water and sediments, ultimately safeguarding the people s welfare, considering the active operation of mining companies in the area.