Effect of thermal processing on toxic heavy metals in edible seaweeds of Gulf of Mannar and their health risk assessment

A significant amount of toxic heavy metals (As, Cd, Hg, Pb, and Cr) in seafood has raised human health concern worldwide. This study investigates the effect of heat processing (boiling, steaming, and microwave cooking) on the toxic metals in wild-harvested (Ulva lactuca and Caulerpa racemosa) and cultured (Kappaphygus aliverzii) edible seaweeds and estimates its potential human health risks. Except As in raw seaweeds, other toxic metals in raw and processed seaweeds were found below the maximum residual limit (MRL) set by the French and the European Union. The target hazard quotient (THQ) of As in raw seaweeds and total THQ (TTHQ) of raw seaweeds were > 1, and other toxic metals were < 1 indicating no health risk from processed seaweeds. The lifetime cancer risk (LCR) value of processed seaweeds were found between the recommended guideline value of 10−6 and 10−4, indicating no carcinogenic risk from heat-processed seaweeds. The recommended maximum seaweed consumption limit (CRmm) was > 100 meals per month with no adverse health effects. Therefore, boiling, steaming, and microwave-cooking methods are recommended to reduce the toxic metal risk from seaweeds. [Display omitted] •Cd, Hg, and Pb in raw and processed seaweeds were found below the maximum residual limit (MRL).•Boiling, steaming, and microwave cooking processes reduced toxic metals.•Recommended seaweed meal consumption found under safe category (≥16 meals/month).•Human health risk assessment indicated no health consequences for seaweed consumers.