Beyond total concentration: A speciation-based framework for health risk assessment in imported seafood

Health risk assessments of toxic elements in aquatic foods historically rely on total concentrations, introducing systematic exposure bias. This study analyzed elemental profiles in imported frozen seafood (29 retail specimens from Ningbo, China) using Inductively Coupled Plasma Mass Spectrometry (ICP-MS) and High-Performance Liquid Chromatography-Inductively Coupled Plasma Mass Spectrometry (HPLC-ICP-MS). Crabs exhibited elevated total arsenic (tAs, mean: 4.27±0.34 mg/kg), resulting in the misclassification of arsenic as the primary health hazard under conventional screening. However, HPLC-ICP-MS confirmed that carcinogenic inorganic arsenic (iAs) was below the limit of quantification (<0.05 mg/kg) across all crab samples, proving total concentration-based screening overestimates systemic risks. Conversely, speciation-based modeling identified methylmercury (MeHg) in fish and cadmium (Cd) in shrimp as the dominant risk drivers. Probabilistic modeling indicated that children consuming imported shrimp faced elevated carcinogenic risks from Cd, with a 79% probability of exceeding the unacceptable threshold (1×10 ⁻⁴ ) under the average ingestion scenario. These findings demonstrate that speciation‑based profiling is essential for precise toxicological characterization at seafood trade gateways, supporting targeted speciation‑based standards to facilitate safe global seafood trade.