Ranking food safety risks related to methylmercury and total mercury in fishery products: a comprehensive quantitative analysis of contamination and human exposure levels

This study quantified methylmercury (MeHg) and total mercury (THg) in 591 fishery products (common octopus, musky octopus, common cuttlefish, common squid, European flying squid, tuna, salt-ripened anchovy, and smoked salmon) originating from various geographical areas (Mediterranean Sea, Atlantic Ocean, Indian Ocean, and Pacific Ocean). An optimized analytical protocol based on direct mercury analysis was employed to determine MeHg and THg concentrations, which were subsequently used to estimate dietary exposure for the Italian population and to characterize the associated health risks across different age groups using probabilistic methods. Common octopus, musky octopus, and tuna, especially of Mediterranean origin, exhibited the highest contamination levels. All cephalopods species showed markedly elevated MeHg/THg ratios (>70%), comparable to those observed in tuna, whereas, while the two processed fishery products displayed significantly lower values. Cephalopods also accounted for most exceedances of the European regulatory limits for THg, with rates of 10 % in common octopus, 17 % in flying squid, and 39 % in musky octopus. Dietary exposure estimates indicated that younger consumers face the highest MeHg and THg intakes and are above safe limits even at average consumption levels. While common cuttlefish, common squid, European flying squid, salt-ripened anchovy, and smoked salmon were identified as low-risk products, octopus emerged as a major and previously underrecognized source of MeHg. Its consumption was indeed associated with over a 70 % probability of surpassing toxicological thresholds in toddlers and children. Seafood-related mercury exposure remains a persistent publichealth concern, and the contribution of underestimated fishery species warrants reconsideration.