Dietary intake and health risk characterization of cadmium, lead, and mercury in milkfish (Chanos chanos) and tilapia (Oreochromis spp.) from aquaculture farms surrounding Manila Bay, Philippines.

Abstract

Milkfish and tilapia are the two major finfish aquaculture species in the Philippines, supporting food security and livelihoods. However, farms surrounding Manila Bay are increasingly exposed to anthropogenic activities, raising concerns about heavy metal contamination. This study quantified cadmium (Cd), lead (Pb), and mercury (Hg) in farmed milkfish and tilapia from 21 municipalities within Manila Bay, and assessed potential human health risk. Heavy metals were analyzed using graphite furnace atomic absorption spectrophotometry (GF-AAS) and mercury vaporizing unit atomic absorption spectrophotometry (MVU-AAS). Health risks were evaluated through estimation of the Lifetime Average Daily Dose (LADD), Hazard Quotient (HQ), and Cancer Risk (CR). Cadmium was the only metal detected in finfish tissues, while Pb and Hg were below method detection limits across all sites. Although all Cd concentrations were below local regulatory limits, exceedance to the EU maximum level (0.05 mg/kg) was observed. Risk assessment showed that LADD values for Cd, Pb, and Hg were within Food and Agriculture Organization/World Health Organization (FAO/WHO) Provisional Tolerable Daily Intake (PTDI) limits, and HQ values were consistently below 1, indicating negligible non-carcinogenic risk. However, elevated Cd CR values in certain locations and age groups suggest potential long-term concerns, highlighting the need for continued site-specific monitoring.