Toxic Metal Exposure from Ecuadorian Seafood: Dietary Exposure and Risk Characterization Across Key Commercial Species

Seafood is an important component of the Ecuadorian diet, particularly in coastal regions; however, contamination from anthropogenic activities has raised concerns about human exposure to toxic metals. This study quantified cadmium (Cd), cobalt (Co), lead (Pb), and total mercury (THg) in shrimp (Protrachypene precipua), shrimp-prawn (Litopenaeus vannamei), blue marlin (Makaira nigricans), and Pacific thread herring (PTH; Opisthonema sp.) purchased in Quito and Manta. A total of 71 samples were analyzed by atomic absorption spectrometry (flame and graphite furnace) and cold-vapor atomic fluorescence spectrometry. Distinct metal accumulation patterns were observed among species: blue marlin exhibited markedly elevated THg concentrations (1117.7 µg/kg) consistent with biomagnification processes, whereas shrimp-prawns showed the highest Cd levels (67.5 µg/kg). Pb and Co levels were below the corresponding limits of quantification in all samples. All detectable concentrations of Cd and THg remained below the maximum levels established by the Codex Alimentarius and European Union regulations. Risk characterization based on Hazard Quotient (HQ) indicated that THg intake from blue marlin exceeded the safety threshold (HQ > 1) across all demographic groups under both mean and maximum consumption scenarios. Additionally, HQ values above 1 were observed for toddlers and children consuming shrimp, shrimp-prawn, and PTH under the maximum exposure scenario. In contrast, Cd exposure remained below the level of concern for all seafood products and population groups. Overall, blue marlin was the primary contributor to potential mercury exposure, particularly among younger consumers.