Safe Food_ Bacteria, Biotechnology, and Bioterrorism - Marion Nestle [120]
In 1990, Monsanto said that its studies had satisfied any doubts about whether rBGH milk is safe for human consumption. That year, FDA scientists reviewed more than 130 studies of the effects of rBGH on cows, rats, and humans and also concluded that the hormone does not affect human health. Critics called this conclusion an unprecedented display of conflict of interest: FDA scientists had produced a favorable evaluation of evidence in support of a drug not yet approved by their agency. Others accused the FDA of colluding with Monsanto because agency scientists could not have conducted the review unless the company had disclosed confidential studies that were not available for evaluation by the general scientific community. A panel of experts recruited by the National Institutes of Health (NIH), however, concluded that milk from rBGH-treated cows was essentially the same—and therefore as safe—as milk from untreated cows. According to one rBGH supporter, the hormone had been tested on 21,000 cows and described in more than 900 research papers by 1992 with no indication of harm to human health.9
Nevertheless, critics continued to raise doubts about the safety of rBGH-milk on two grounds: antibiotics and a substance called insulin-like growth factor-1 (IGF-1). The concern about antibiotics derives from observations that cows given rBGH develop more frequent infections of their udders (mastitis). The more milk cows produce, the more likely they are to develop mastitis, and rBGH increases milk production. Because farmers treat the infections with antibiotics that can linger in milk and meat, eating foods from treated animals might contribute to selection for antibiotic-resistant bacteria. On this basis, the General Accounting Office (GAO) urged the FDA not to approve rBGH until issues related to mastitis could be resolved. Federal regulations require the FDA to test for antibiotic residues in milk, but the agency is able to test for just a small fraction of animal drugs in common use—just 4 out of 82 in one study—suggesting a lack of ability to monitor such substances. Because of this regulatory gap, another federal committee recommended that the FDA ban rBGH until the antibiotic risks could be evaluated. The Republican administration in power in 1992, however, was committed to a policy of industry deregulation, and it ignored the recommendations.10
IGF-1 concerns critics for three reasons: (1) rBGH increases levels of this factor in cow’s milk, (2) IGF-1 in cows is chemically identical to human IGF-1, and (3) higher levels of IGF-1 in cow’s milk might stimulate premature growth in human infants or cancer in adults. It is difficult to evaluate this last contention given the current state of research. Population studies associate high levels of IGF-1 in blood with a higher risk of prostate cancer in men and breast cancer in premenopausal (but not post-menopausal) women and, perhaps, with a greater risk of high blood pressure, but these findings do not necessarily have anything to do with drinking milk; high IGF-1 levels could be due to genetic or other dietary causes.11 The factor ought to be inactivated during processing and digestion, but some seems to be absorbed intact. The research gaps have encouraged lingering doubts, demands for reassessment of the safety of rBGH, and lawsuits against the FDA. They also encouraged one anti-rBGH activist, Robert Cohen, to go on a hunger strike in 1999—one of the more extreme forms of protest against foods made with transgenic ingredients.12
The Social Issues. Protests