Methylmercury contamination in Mediterranean seafood: Exposure assessment and cost of illness implications

Methylmercury (MeHg) is a widespread contaminant that bioaccumulates in marine food webs, including those in the Mediterranean sea. It poses serious health risks, especially to developing infants and children, where exposure can cause neurological damage and developmental delays. In addition to health concerns, high MeHg levels in seafood can lead to economic losses through cognitive impairments that reduce productivity. Despite seafood being a dietary staple in Mediterranean countries, the full extent of MeHg's health and economic impacts remains underexplored, especially with the rising international trade. This study aims to (a) estimate MeHg exposures in Mediterranean populations from consumption of Mediterranean seafood and (b) quantify the economic costs associated with MeHg intake. We assessed population exposures in Mediterranean countries by combining a highly granular seafood supply data on Aquatic Resource Trade in Species (ARTIS), alongside Global Dietary Database (GDD) and review of MeHg levels in Mediterranean seafood. The economic cost was then derived by linking MeHg intake to productivity losses associated with cognitive deficits. As a result, we estimate that Mediterranean countries experience over €10 billion in annual economic losses due to IQ-related productivity decline associated with MeHg exposure from consuming seafood sourced from various fishing areas of the Mediterranean Sea. The novelty of this research lies in its transdisciplinary approach to MeHg impact assessment that incorporates highly detailed seafood supply data with dietary surveys, and scientific literature to provide a more realistic and detailed view of MeHg exposures and the associated cost-of illness from local seafood consumption accross Mediterranean countries. These findings highlight a critical aspect of MeHg management: while international trade can mitigate local exposure by providing access to less-contaminated imports, it simultaneously exports the contamination burden to other regions. This duality emphasizes the importance of global cooperation in addressing seafood safety and managing transboundary MeHg risks.