Arsenic metabolites in humans after ingestion of wakame seaweed
1 Division of Clinical Laboratory Science, Department of Medical Risk Management, Faculty of Risk and Crisis Management, Chiba Institute of Science, Chiba, Japan
2 Research Unit of Environmental Toxicology and Carcinogenesis, School of Pharmacy, Nihon University, Chiba, Japan
3 Department of Preventive Medicine and Environmental Health, Graduate School of Medicine, Osaka City University, Osaka, Japan
4 Department of Hygiene and Preventive Medicine, School of Medicine, Showa University, Tokyo, Japan
5 Research Center for Occupational Poisoning, Kansai Rosai Hospital, Japan Labour Health and Welfare Organization, Hyogo, Japan
Seaweed contains large amounts of various arsenic compounds such as arsenosugars (AsSugs), but their relative toxicities have not yet been fully evaluated. A risk evaluation of dietary arsenic would be necessary. After developing an arsenic speciation analysis of wakame seaweed (Undaria pinnatifida), we conducted a wakame ingestion experiment using volunteers. Five volunteers ingested 300 g of commercial wakame after refraining from seafood for 5 days. Arsenic metabolites in the urine were monitored over a 5-day period after ingestion. Total arsenic concentration of the wakame seaweed was 34.3 ± 2.1 mg arsenic/kg (dry weight, n = 3). Two AsSugs, 3-[5′-deoxy-5′-(dimethyl-arsinoyl)-β-ribofuranosyloxy]-propylene glycol (AsSug328) and 3-[5′-deoxy-5′-(dimethyl-arsinoyl)-β- ribofuranosyl-oxy]-2-hydroxypropyl-2,3-dihydroxy-propyl phosphate (AsSug482) were detected, but arsenobetaine, dimethylarsinic acid (DMA), monomethylarsonic acid, and inorganic arsenics (iAs) were not detected. The major peak was AsSug328, which comprised 89% of the total arsenic. Approximately 30% of the total arsenic ingested was excreted in the urine during the 5-day observation. Five arsenic compounds were detected in the urine after ingestion, the major one being DMA, which comprised 58.1 ± 5.0% of the total urinary arsenic excreted over the 5 days. DMA was believed to be metabolized not from iAs but from AsSugs, and its biological half-time was approximately 13 h.
Key words: arsenosugar / metabolite / organoarsenic / seaweed / urine
© Owned by the authors, published by EDP Sciences, 2013
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