The European Food Safety Authority (EFSA) has concluded that the current tolerable weekly intakes (TWIs) for inorganic mercury and methylmercury remain valid, following a review of the 2024 Toxicological Profile for Mercury issued by the US Agency for Toxic Substances and Disease Registry (ATSDR). In a statement published on 22 June 2026, EFSA found no need to update its 2012 risk assessment for inorganic mercury, as a new 28-day rat study cited by ATSDR was deemed unsuitable for deriving a reference point for dietary risk assessment. For methylmercury, EFSA determined that the ATSDR's minimal risk level is not scientifically more robust than its own TWI, and the existing value of 1.3 μg/kg body weight per week remains appropriate.
The statement was prepared at the request of the European Commission, which asked EFSA to evaluate the completeness of ATSDR's literature search, the appropriateness of critical studies used for hazard characterisation, the differences between the 2012 EFSA health-based guidance values and the 2024 ATSDR minimal risk levels, and whether an update of EFSA's 2012 opinion is needed. EFSA's CONTAM Panel endorsed the statement before approval. While EFSA acknowledged that some key methodological steps were not fully reported in the ATSDR document, it considered it unlikely that major relevant publications were missed. For inorganic mercury, the TWI of 4 μg/kg bw per week remains unchanged. For methylmercury, EFSA noted that differing reporting approaches on hazard characterisation methodology appear to be the main driver of the differing guidance values, but found no clear indication that the ATSDR's chronic MRL of 0.1 μg Hg/kg bw per day (equivalent to 0.7 μg/kg bw per week) is more robust than EFSA's TWI of 1.3 μg/kg bw per week. However, EFSA noted that advances in risk assessment methodology and new evidence since 2012 might merit an update of the 2012 opinion.
The decision has implications for EU risk assessment and consumer protection. The unchanged TWIs mean that dietary exposure assessments for mercury will continue to use the 2012 benchmarks, affecting how food safety authorities evaluate risks from fish consumption. High fish consumers, particularly pregnant women, remain the most vulnerable group, as methylmercury exposure can exceed the TWI up to six-fold. The statement also feeds into a broader risk-benefit assessment of fish consumption being conducted by EFSA's Scientific Committee, which covers multiple contaminants including dioxins, PFAS, and arsenic. For industry, the confirmation provides regulatory stability, but the suggestion that an update may be warranted signals potential future tightening of limits, which could affect fish importers and aquaculture producers. The European Commission will consider whether to request a full update of the 2012 opinion based on EFSA's recommendation.