ARE BT CROPS SAFE?
ARE BT CROPS SAFE?
September 2003 Nature Biotechnology, Vol. 21 N0. 9 www.nature.com Mike Mendelsohn, John Kough, Zigfridais Vaituzis & Keith Matthews (U.S. Environmental Protection Agency) Via AgBioView at www.agbioworld.org Introduction and conclusion 'The US EPA's analysis of Bt crops finds that they pose no significant risk to the environment or to human health.' Bacillus thuringiensis (Bt) is a naturally occurring soil bacterium that produces proteins active against certain insects. Beginning in the mid-1990s, crop plants expressing Bt genes were commercialized in the United States. Cry1Ab and Cry1F Bt corn are effective in controlling certain pests of corn (European corn borer, corn earworm and southwestern corn borer), and Cry1Ac Bt cotton is effective in controlling certain pests of cotton (tobacco budworm, cotton bollworm and pink bollworm). Beyond the economic benefits to growers, the use of Bt corn and Bt cotton result in less risk to human health and the environment than chemical alternatives. In 2001, the US Environmental Protection Agency (EPA; Washington, DC, USA) reassessed the four still registered, but expiring, Bt crops that had been accepted for agricultural use in the preceding six years (from 1995 to October 2001; Table 1). The Bt crop reassessment approvals included provisions to prevent gene flow from Bt cotton to weedy relatives, increase research data on potential environmental effects and strengthen insect resistance management. From this reassessment, the EPA has determined that Bt corn and Bt cotton do not pose unreasonable risks to human health or to the environment. In this article, we summarize the supporting data and conclusions of the EPA. The complete reassessment document1, Biopesticides Registration Action Document (BRAD)--Bacillus thuringiensis Plant-Incorporated Protectants, which describes in detail the reassessment process, along with extensive references, can be found on the EPA website at http://www.epa.gov/pesticides/biopes...s/bt_brad.htm. cut Conclusions: In the fall of 2001, the EPA completed a comprehensive reassessment of the time-limited registrations for all existing Bt corn and cotton PIPs. As part of this reassessment, the agency decided to extend the registrations with additional terms and conditions, including requiring confirmatory data to ensure protection of nontarget organisms and lack of accumulation of Bt proteins in soils, measures to limit gene flow from Bt cotton to wild (or weedy) relatives, and a strengthened IRM program, especially in regard to compliance. The Bt cotton registration is now set to automatically expire on September 30, 2006 except for the external, unsprayed refuge option, which will expire September 30, 2004. The Bt corn registrations are now set to automatically expire on October 15, 2008. This reassessment was designed to assure that the decisions on the renewal of these registrations were based on the most current health and ecological data, and that the process was conducted in an open and transparent public process that incorporated sound and current science and substantial public involvement. |
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