Safe Food_ Bacteria, Biotechnology, and Bioterrorism - Marion Nestle [111]
Indeed, one of the chief complaints of environmentalists is that transgenic crops will increase the use of agricultural chemicals, especially of Monsanto’s Roundup. Farmers planted Roundup Ready soybeans on just 1 million acres in 1996 but on 48 million acres in 2001; they applied Roundup to 20% of farm acres in 1995 but to 62% in 1999.34 Roundup generates billions of dollars in annual sales, and Monsanto benefits twice; it sells the herbicide and the seeds for the crops that resist it. The company’s studies show that Roundup Ready soybeans survive when doused with the chemical, and are as nutritious when fed to rats as conventional soybeans.35 Whether the use of Roundup is environmentally beneficial is, of course, a debatable issue. Monsanto points out that it registered Roundup as an herbicide in 1974 with minimal subsequent evidence of hazard: “Consumers benefit from Roundup Ready soybeans because farmers can control weeds better . . . with less herbicide while using a herbicide with the best environmental profile.” To bolster that argument, the company cites two lines of research: Roundup binds so tightly to soil particles that the chemical does not harm nearby vegetation (and, therefore, is unlikely to move to groundwater), and it decomposes naturally to benign substances.36
Critics, however, raise alarms about the heavy use of this product: Roundup may induce weeds to develop resistance; it may poison fish, earthworms, or other beneficial creatures; and it may disrupt soil ecology. From a biochemical standpoint, resistance to Roundup is not difficult to achieve. Its active chemical, glyphosate, inhibits the action of an enzyme that helps make three amino acids needed to construct plant proteins. Plants cannot make proteins when this enzyme is blocked. Bacteria, however, are well known to produce a mutant variant of this enzyme that is completely unaffected by glyphosate; they do so through “point” mutations (mutations that alter just one amino acid) or mutations that cause the enzyme to be produced in such large amounts that glyphosate becomes ineffective. Such mutations could occur in plants as well as in bacteria. The transfer of Roundup resistance to weeds through pollination also is probable, and has already occurred. The idea of widespread resistance to Roundup is not improbable, and it alarms the industry as well as environmentalists.37
The most highly critical statements about the use, toxicity, and persistence in soil of Roundup can be traced to an exhaustive scientific review published in 1995. The review identifies toxic effects from the chemical itself as well as from ingredients used in its formulation. It describes studies on experimental animals in which Roundup caused eye and skin irritation, cardiac depression, gastrointestinal distress, reduced weight gain, increased frequency of tumors, and reduced sperm counts. In people, Roundup appears as the most common cause of pesticide-related illness among landscape workers and the third most common cause of such illness among agricultural workers. Roundup residues persist in vegetables a year after treatment and in soil for more than a year. Researchers report that Roundup produces toxic effects on beneficial insects, fish, birds, and earthworms; eliminates vegetation used as food and shelter for animals and birds; and reduces the activity of bacteria that fix nitrogen and perform other “friendly” tasks.38 Whether these effects are worse than those produced by the pesticides replaced by Roundup is a question that demands further research. In the absence of convincing studies, such decisions are a matter of opinion.
Underlying questions about the potential risks of transgenic plantings are more general concerns about what Roundup