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Mr. Bob Speller
Chair, Standing Committee on Agriculture and Agri-food
House of Commons
I am writing on behalf of the Toronto Board of Health regarding Health Canada's response to the motion of the Standing Committee on Agriculture and Agri-food Regarding rBST, dated June 21, 1995.
The Board of Health has asked me to convey to you its concerns about Health Canada's summary of the Human Safety Evaluation of rBST. These concerns are organized under two categories.
What criteria have Health Canada used for determining which evidence is valid? 0
In several places in their report, Health Canada draws conclusions that have been challenged by other scientists. Health Canada does not indicate that there is a debate in the scientific literature(1), does not cite any of the evidence that contradicts their conclusions, and provides no criteria for ignoring or eliminating such literature from their review.
1. Health Canada concludes that variations in milk components, BST levels and IGF-1 levels associated with rBGH treatment fall within normal ranges of variability. Other scientists(2) have challenged these conclusions. On what basis has Health Canada ignored or rejected the evidence from these scientific papers?
2. Health Canada states "According to the literature ... [IGF-1 from rBST-treated milk] is not biologically active" (p. 9). Other scientists believe that it is(3), in part because it is protected from degradation by the presence of casein(4). Health Canada claims that any literature suggesting that IGF-1 is orally active is unsubstantiated. Yet even scientists promoting rBST use have concluded that " ... it could be considered an oversight ... to suggest that ingested IGF-1 is inactive. Many more potential effects of ingested IGF-1 on the gastrointestinal tract and the local immune system of the gut need to be explored."(5). On what basis does Health Canada reject evidence contradicting their conclusions?
3. Health Canada argues that any additional levels of IGF-1 in the milk supply would be inconsequential because the human body already contains much higher levels. Other scientists argue, however, that because of the manner by which this extra IGF-1 enters the body, and the constituents found in milk, the human body may react differently to IGF-1 consumed in milk. As well, IGF-1 exists in a number of other forms, some of which are more biologically active(6). Health Canada does not acknowledge the existence of these forms, nor does it comment on how little we understand of them and their role in the human gut. On what basis, then, for such a critical component of the reivew, does Health Canada make the claim that any additional levels of IGF-1 are inconsequential?
What the Health Canada report indicates about problems with the drug review process
4. There are two ways in which rBST-treated milk is a potential health hazard: one results from consumption of milk that has been modified by treatment (addressed by Health Canada); the second is the health effects resulting from the public's avoidance of milk consumption. Canadian surveys and the Task Force report conclude that a significant percentage of consumers will reduce their consumption, having potentially negative economic and health impacts(7). There is no requirement for Health Canada to examine such a health impact, and there is no indication from their report that they see this as part of their review.
5. Health Canada reports that it "has been and/or will be considering as part of its review ... a number of additional issues that have been raised and noted in the Task Force report." (p. 6). The Board of Health has been concerned that the drug review process is too narrowly defined, and that Health Canada is not required to take account of many issues that health professionals feel are relevant. This comment would appear to confirm this concern. Were it not the intervention of the House Standing Committee, it appears many issues regarding IGF-1 would not be examined by the Bureau of Veterinary Drugs. The terms of reference should ensure that broad input can be solicited.
6. The Health Canada submission does not touch on any matters that would reveal anything about the state and validity of submitted industry data. This is presumably because such data is considered proprietary. The Board of Health is concerned that information with such potentially significant and widespread public health implications could be held in secrecy because one company feels revealing it might harm its profits.
7. Health Canada's closing paragraph suggests that the overall review of rBGH has not been concluded, but the words and tone used indicate otherwise. The reading of the Board of Health is that Health Canada has already concluded that there are no health problems associated with rBST and IGF-1. Based on the literature cited, most of it pre-1991, it would appear that more recent work has not been taken into account. In turn this suggests that Health Canada reached this conclusion some time ago, and has not been actively keeping up with new reports. The pattern of literature citation, very similar to that employed by the drug's manufacturers, also leads the Board to wonder if, in reviewing a license, Health Canada is only permitted to review scientific literature submitted by the applicant?
The Toronto Board of Health remains deeply concerned about both the process of reviewing this drug and the conclusions that appear to have been reached.
We urge the Standing Committee:
Thank you very much for considering these comments and recommendations.
Chair, Toronto Board of Health
for the City of Toronto Health Unit
cc. Rt. Hon. Jean Cretien
Hon. Diane Marleau, Minister of Health
Hon. Ralph Goodale, Minister of Agriculture and Agri-food
Hon. Herb Gray, Government House Leader
Michel Gauthier, Opposition House Leader
Elwin Hermanson, Reform House Leader
All members of the House of Commons Standing Committee on Agriculture and Agri-food
All members of the House of Commons Standing Committee on Health
Marc Toupin, Clerk, Standing Committee on Agriculture and Agrifood
Nancy Hall, Clerk, Standing Committee on Health
Gordon White, Association of Local Ontario Health Agencies
1. Note that we have preferentially selected references that provide a summary of the contrary view. From these scientific articles, other citations that Health Canada may not be aware of can be obtained.
2. Mepham, T.B. et al. 1994. Safety of milk from cows treated with bovine somatotrophin. The Lancet 344(8916):197, July 16 and 344(8934):1445-46, November 19.
Mepham, T.B. 1992. Public health implications of bovine somatotrophin use in dairying: discussion paper. J. Royal Soc. Medicine 85:736-739.
Kronfeld, D.S. 1991. Bovine Somatotrophin. J. Amer. Medical Assoc. 265:1389. (Kronfeld has written extensively on this subject, and on BST-induced mastitis.)
Bitman, J., Wood, D.K., Tyrrell, H.F. et. al. 1984. Blood and milk lipid responses induced by growth hormone administration in lactating cows. J. Dairy Sci. 67:2873-80.
3. Mepham, T.B. and Schofield, P.N. 1995. Health aspects of BST milk. International Dairy Federation Nutrition Week Paper. Paris, France. June, 1995.
Feenstra, G. 1993. Is BGH sustainable? the consumer perspective. In: B. Liebhardt (ed.). The Dairy Debate: consequences of Bovine Growth Hormone and Rotational Grazing techniques. University of California. Davis, CA. Pp. 1- 63.
4. Xian, C.J., Shoubridge, C.A. and Read. L.C. 1995. Degradation of insulin-like growth factor - 1 in the adult rat gastrointestinal tract is limited by a specific antiserum or the dietary protein casein. J. Endocrinol. (in press).
5. Burton, J.L., McBride, B.W., Block, E., Glimm, D.R. and Dennelly, J.J. 1994. A review of bovine growth hormone. Can. J. Animal Sci. 74:167-201.
6. Mepham, T.B. 1992. Public health implications of bovine somatotrophin use in dairying: discussion paper. J. Royal Soc. Medicine 85:736-739.
7. OPTIMA. 1994. Understanding the Consumer Interest in the New Biotechnology Industry. Industry Canada, Ottawa.
Copyright © 1995 Toronto Board of Health. Reprinted with permission. All rights reserved.
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