Metal concentrations in Mugil liza (Valenciennes, 1836) from a southern Brazilian estuary: tissue distribution and human health risk assessment

Metal contamination poses global environmental and public health concerns due to its persistence and potential for biomagnification in aquatic food webs. This study investigated cadmium (Cd), copper (Cu), lead (Pb), and zinc (Zn) concentrations in muscle and liver tissues of Mugil liza (Valenciennes, 1836), a commercially important fish species from the Laguna Estuarine System (LES), southern Brazil. Metal concentrations were quantified and compared with legal safety thresholds, and potential human health risks were assessed for muscle tissue using the Target Hazard Quotient (THQ). Associations with tissue type, fish size, and reproductive stage were also evaluated. In muscle, metal concentrations (mg/kg wet weight) followed the order Zn (3.23–8.69) > Cu (0.06–1.69), with Cd and Pb below detection limits. In liver tissue, concentrations were: Cu (53.86–3,08) > Zn (up to 238.98) > Cd (0.09–3.21); Pb was not detected. Legal limits were exceeded only in liver samples, while muscle tissue remained within safe limits for human consumption. THQ values for all metals in muscle were below 1, indicating low potential risk to human health. Metal concentrations in M. liza showed slight variation across reproductive stages, with higher hepatic levels observed in immature and post-spawning males and in post-spawning females. Generalized Additive Models (GAM) indicated that, except for Zn in muscle, metal concentrations generally increased with fish length in both tissues. These results demonstrate that M. liza predominantly accumulates metals in the liver, suggesting potential ecological risks to predators through trophic transfer, while muscle concentrations confirm safety for human consumption. • Zn > Cu in muscle and Cu > Zn > Cd in liver of M. liza from southern Brazil. • Toxic metals (Cd and Pb) were below quantification limits in muscle. • Metal levels varied with tissue type, fish size and reproductive stage. • Cu and Zn in muscle were within safe levels for human consumption. • Legal limits for Cd, Cu, and Zn were exceeded in liver, posing risk to predators.