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.