Herbicide to remain in U.S. use

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    Herbicide to remain in U.S. use

    To the disappointment but not surprise of the Natural Resources Defense Council (NRDC), its 2008 petition to the U.S. Environmental Protection Agency to remove the herbicide known as 2,4-D from U.S. markets has been denied. [ Jaclyn Sindrich, EPA denies environmental group's petition on 2,4-D, Farm Chemicals International, April 10, 2012, at http://www.farmchemicalsinternational.com/news/cropprotection/?storyid=3485 ]

    The herbicide--2,4-dichlorophenoxyacetic acid--was invented in 1941 by Prof. Ezra J. Kraus at the University of Chicago and Dr. John W. Mitchell at the U.S. Department of Agriculture, hoping to increase crop yields. [ Charles L. Hamner and Harold B. Tukey, The herbicidal action of 2,4 dichlorophenoxyacetic and 2,4,5 trichlorophenoxyacetic acid on bindweed, Science 100(2590):154-155, 1944, extract at http://www.sciencemag.org/content/100/2590/154.extract ]

    The chemical acts as a plant hormone, stunting growth of dandelion, plantain, ragweed, chickweed and other fast-growing broadleaf plants while leaving unaffected most grasses, pulses and grains. Rhône-Poulenc obtained manufacturing rights to 2,4-D in 1942 and introduced it to U.S. markets in 1946, under the brand name Weedone, which was distributed by the American Chemical Paint Co. at a retail price of about $10 a gallon, enough for around a half acre. Despite inflation, bulk chemical prices are about the same today.

    Several derivatives in the chlorophenoxy family were quickly found, but 2,4-D has remained the largest volume herbicide product since World War II. After patent rights to it expired, Dow, BASF and other large chemical companies began to produce it. During the Vietnam War, Dow supplied Agent Orange for the U.S. war effort, which was equal parts 2,4-D and the closely related 2,4,5-T. Emergence of resistance to the widely used glyphosates, best known as Roundup from Monsanto, has led to resurgence in use of 2,4-D.

    The U.S. regulates herbicides under the Federal Insecticide, Fungicide and Rodenticide Act of 1947 (PL 80-104, as amended), a replacement for the Federal Insecticide Act of 1910. The federal law requires EPA to evaluate risks versus benefits. After a long controversy, the Walker Bush administration allowed reregistration of 2,4-D in 2005 with "mitigation measures" to reduce airborne drifts from the sites of use. [ Dr. Steven P. Bradbury, to Dr. Gina Solomon and Mae Wu of NRDC, U.S. Environmental Protection Agency, April 7, 2012, at http://www.epa.gov/pesticides/chem_search/reg_actions/24d/24d-fifra-response.pdf ]

    EPA acknowledged risks of 2,4-D to health of people and wildlife but asserted that benefits outweigh risks. This year, EPA has upheld the 2005 findings, saying that NRDC's petition to reverse them considered only risks and not benefits. Apparently anticipating that its petition would be denied, in February NRDC filed a federal lawsuit, seeking to overturn the EPA ruling. [ Jackie Wei, NRDC lawsuit seeks to ban Agent Orange ingredient, Natural Resources Defense Council, February 23, 2012, at http://www.nrdc.org/media/2012/120223.asp ]

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    More opposition to 2,4-D

    In today's NY Times, Andrew Pollack, a business reporter who focuses on health care and biotechnology, again takes on 2,4-D--the oldest herbicide and still in common use after more than 70 years. After getting its reputation sullied by compounding Agent Orange with it during the Vietnam War, Dow retrenched in the market but continues to produce it as "2,4-D Ester 500 EC," the iso-octyl ester of 2,4-dichlorophenoxyacetic acid. [ Andrew Pollack, Dow weed killer nearing approval runs into opposition, New York Times, April 25, 2012, at http://www.nytimes.com/2012/04/26/business/energy-environment/dow-weed-killer-runs-into-opposition.html ]

    The advertised benefit of this 2,4-D variant is that it readily emulsifies in water, making spraying easier to control. Dow's potentially stronger interest is a genetically engineered maize, intended to be grown as market corn, that will tolerate 2,4-D, which kills current maize crops. Along with Monsanto, Dow has also been reported to be developing herbicide-tolerant varieties of cotton and soybeans. [ Jack Kaskey, Bloomberg News, Dow and Monsanto herbicide-tolerant crops need U.S. study, Business Week, April 18, 2012, at http://www.businessweek.com/news/2012-04-18/dow-monsanto-herbicide-tolerant-crops-need-u-dot-s-dot-study ]

    The most prominent opponent mentioned in both news articles is Save Our Crops Coalition, a group of Indiana vegetable farmers who claim other crops will become "collateral damage"--using an analogy from the Vietnam War--if expansions in 2,4-D agricultural uses are encouraged by approval of herbicide-tolerant crops. [ Non-target damage, Save Our Crops, 2011, at http://saveourcrops.org/non-target-damage/ ]