Chemical forms of mercury and selenium in fish following digestion with simulated gastric fluid.
Fish is a major dietary source of potentially neurotoxic methylmercury compounds for humans. It is also a rich source of essential selenium. We have used in situ mercury L(III)-edge and selenium K-edge X-ray absorption spectroscopy to chemically characterize the methylmercury and selenium in both fresh fish and fish digested with simulated gastric fluid. For the mercury, we confirm our earlier finding [ Harris et al. ( 2003 ) Science 301 , 1203 ] that the methylmercury is coordinated by a single thiolate donor, which resembles cysteine, and for the selenium, we find a mixture of organic forms that resemble selenomethionine and an aliphatic selenenyl sulfide such as Cys-S-Se-Cys. We find that local chemical environments of mercury and selenium do not change upon digestion of the fish with simulated gastric fluid. We discuss the toxicological implications for humans consuming fish.
George
Graham N
GN
Department of Geological Sciences, University of Saskatchewan, 114 Science Place, Saskatoon, Saskatchewan S7N 5E2, Canada. g.george@usask.ca
Singh
Satya P
SP
Prince
Roger C
RC
Pickering
Ingrid J
IJ
D000818:Animals; D004063:Digestion; D005399:Fishes / Q000378:metabolism*; D005506:Food Contamination; D005753:Gastric Mucosa / Q000378:metabolism*; D008767:Methylmercury Compounds / Q000737:chemistry* / Q000378:metabolism / Q000633:toxicity; D012643:Selenium / Q000737:chemistry* / Q000378:metabolism / Q000633:toxicity; D014874:Water Pollutants, Chemical / Q000737:chemistry*
D008767:Methylmercury Compounds; D014874:Water Pollutants, Chemical; D012643:Selenium; C004925:methylmercuric chloride