October 6, 2003 – The mercury in fish may not be as toxic as previously thought, if a Canadian researcher is to be believed.
No one disputes that some fish contain a potentially dangerous amount of a type of mercury called methylmercury, a fact that explains why several governments recommend that women who are pregnant or breastfeeding limit their consumption. However, no one knows exactly what kind of methylmercury it is.
Until now, studies of the toxicity of mercury have mainly been based on the assumption that it is methylmercury chloride. However, Professor Graham George of the University of Saskatchewan, after carrying out a detailed analysis, believes that it may instead be the methylmercury-cysteine complex.1.
The toxicological properties of this substance are still poorly understood, but in laboratory tests it was found to be less toxic than methylmercury chloride. New studies must now be performed to confirm this finding.
In addition, researchers at the University of Quebec in Montreal recently found that canned albacore tuna is not completely free of mercury, contrary to what Health Canada claims. Thus, 40% of the samples studied had contamination rates well above international safety standards. Light tuna in water or oil would be a better choice.
Health Canada advises women who are pregnant (or thinking of becoming) to limit their consumption of certain fish containing high levels of mercury to one meal per month, such as shark, swordfish, fresh tuna and marlin, for fear that this substance is transmitted to the fetus and does not interfere with its development. The same recommendations apply to young children.
Jean-Benoit Legault – PasseportSanté.net
From L’actualité Médicale, WebMD and Le Devoir; August 28, September 19 and 25, 2003.
1. Harris HH, Pickering IJ, George GN. The chemical form of mercury in fish. Science 2003 Aug 29; 301 (5637): 1203.