title: Oral bioaccessibility of toxic metals in contaminated oysters and relationships with metal internal sequestration.
abstract: The Hong Kong oysters Crassostrea hongkongensis are widely farmed in the estuarine waters of Southern China, but they accumulate Cu and Zn to alarmingly high concentrations in the soft tissues. Health risks of seafood consumption are related to contaminants such as toxic metals which are bioaccessible to humans. In the present study, we investigated the oral bioaccessibility of five toxic metals (Ag, Pb, Cd, Cu and Zn) in contaminated oysters collected from different locations of a large estuary in southern China. In all oysters, total Zn concentration was the highest whereas total Pb concentration was the lowest. Among the five metals, Ag had the lowest oral bioaccessibility (38.9-60.8%), whereas Cu and Zn had the highest bioaccessibility (72.3-93.1%). Significant negative correlation was observed between metal bioaccessibility and metal concentration in the oysters for Ag, Cd, and Cu. We found that the oral bioaccessibility of the five metals was positively correlated with their trophically available metal fraction (TAM) in the oyster tissues, and negatively correlated with metal distribution in the cellular debris. Thus, metal partitioning in the TAM and cellular debris controlled the oral bioaccessibility to humans. Given the dependence of oral bioaccessibility on tissue metal contamination, bioaccessibility needs to be incorporated in the risk assessments of contaminated shellfish.
authors.affiliation: Division of Life Science, Hong Kong University of Science and Technology (HKUST), Clearwater Bay, Kowloon, Hong Kong.
authors.forename: Shi
authors.initials: S
authors.lastname: Gao
authors.affiliation: Division of Life Science, Hong Kong University of Science and Technology (HKUST), Clearwater Bay, Kowloon, Hong Kong. Electronic address: wwang@ust.hk.
authors.forename: Wen-Xiong
authors.initials: WX
authors.lastname: Wang
mesh_terms: D000818:Animals; D002681:China; D003300:Copper / Q000008:administration & dosage / Q000032:analysis / Q000493:pharmacokinetics; D049896:Crassostrea / Q000187:drug effects / Q000378:metabolism*; D004784:Environmental Monitoring; D063366:Estuaries; D005506:Food Contamination; D059022:Food Safety; D000075322:Heavy Metal Poisoning; D006723:Hong Kong; D006801:Humans; D019216:Metals, Heavy / Q000008:administration & dosage / Q000032:analysis / Q000378:metabolism / Q000493:pharmacokinetics; D009055:Mouth; D011041:Poisoning / Q000378:metabolism; D018570:Risk Assessment; D012758:Shellfish; D057096:Shellfish Poisoning; D014874:Water Pollutants, Chemical / Q000008:administration & dosage / Q000493:pharmacokinetics / Q000633:toxicity; D015032:Zinc / Q000008:administration & dosage / Q000032:analysis / Q000493:pharmacokinetics
chemical_list: D019216:Metals, Heavy; D014874:Water Pollutants, Chemical; D003300:Copper; D015032:Zinc
keywords: Detoxification; Health risk assessment; Metals; Oral bioaccessibility; Oysters