The selenium content in swordfish (xiphias gladius) in relation to total mercury content

Total mercury and selenium concentrations were determined in 47 swordfish caught in the north-west Atlantic ocean. Only 10 swordfish had total mercury levels equal to or below the World Health Organization (W.H.O.) limit of 0.5 μg of mercury/g of fish. All fish had significant quantities of selenium. All fish that contained mercury up to 2 mg/g had a molar excess of selenium compared to mercury.Two hundred and fifty-one swordfish were analyzed for total mercury and only 12 fish or 4.8% contained more than 2 ng/g total mercury; therefore, it was concluded that in most swordfish there was a molar excess of selenium in relation to mercury.Since selenium has been shown to lower the toxicity of methyl mercury in animal studies by other investigators, it was suggested that the use of swordfish for food should be reviewed.