Michael Hansen, Ph.D., Research Associate
Consumer Policy Institute*, Consumers Union
FDA’s Safety Assessment of Recombinant Bovine Growth Hormone
December 15, 1998
I would like to talk to you about some disturbing information on FDA’s review of recombinant bovine growth hormone (rbGH) which emerged in September from a Canadian investigation.
The Canadian investigation, conducted by staff of Health Canada, their equivalent of the FDA, reveals that US FDA misled the public about a key 90-day Monsanto rbGH rat feeding study. FDA, in an article in Science magazine in 1990, said that the study showed “no toxicologically significant changes” in the rbGH-treated rats. Based largely on this conclusion, FDA did not require the normal human safety toxicological assessment usually required for a veterinary drug.
This 90-day Monsanto rat feeding study has never been published. However the Health Canada review team obtained the complete study and found that it actually showed that 20 to 30 percent of the rats in the high dose group developed primary antibody responses to rbGH, suggesting it was being absorbed into the bloodstream. There were also cysts on the thyroid in some male rats. In the view of the Canadian scientists, and in our view as well, these are toxicologically significant changes, and should have triggered a full human health review, including assessment of potential carcinogenic, immunological and teratogenic effects. Yet the FDA did not even mention the existence of these results when they discussed this study in their 1990 Science article.
We are deeply concerned that Judith Juskevich and Greg Guyer, then both staff scientists with the FDA’s Center for Veterinary Medicine, reported on this study in Science magazine, a highly respected journal, in such a misleading manner. Since Health Canada had the full study, we assume that all the data were provided to FDA as well. However, if Monsanto misled FDA by withholding some of the data from the study, then we call on FDA to make this clear and take appropriate action against Monsanto. Consumers depend on both companies and regulators to be objective and truthful in regulatory proceedings. Consumer confidence in the safety of the food supply depends on this trust.
We would like to be clear that this study, by itself, in no way proves that rbGH, which is present in the milk of rbGH treated dairy cows, poses a hazard to human health. But neither does it show that there is no possibility of any healthy hazard, as FDA claimed it did. This study should in fact have triggered a full toxicological assessment of rbGH’s safety to humans.