Administrator Gina McCarthy

U.S. Environmental Protection Agency

1200 Pennsylvania Ave NW

Washington, DC 20460

RE: Dow AgroSciences application to amend their 2,4-D choline salt herbicide for use on 2,4-D tolerant corn and soybeans. Docket EPA-HQ-OPP-2014-0195

Dear Administrator McCarthy,

We the undersigned scientists, medical professionals, and researchers are writing to urge the US Environmental Protection Agency not to register a double herbicide mix of 2,4-D and glyphosate (the 'Enlist DuoTM' weed killer) for farm field spraying in combination with a new breed of genetically engineered corn and soybeans.

This 2,4-Dichlorophenoxyacetic acid (2,4-D) and glyphosate herbicide system developed by Dow AgroSciences, a wholly owned subsidiary of the Dow Chemical Company, would put public health at risk if sprayed on millions of acres of cropland.

Dow Chemical Company promotes 2,4-D-resistant corn and soybeans to be used in conjunction with Enlist DuoTM because the widespread planting of the glyphosate-tolerant Roundup Ready corn and soybeans has resulted in accelerated herbicide resistance in numerous weed species. [1]

Now, instead of re-evaluating the genetically engineered crop strategy in the United States, the US Department of Agriculture and EPA are close to approving the 2,4-D-resistant corn and soybeans despite the risks that the increased use of 2,4-D would pose to human health and the environment.

A host of adverse consequences

2,4-D is a notorious herbicide that has been linked with adverse health effects to the thyroid [2] and an increased risk of non-Hodgkin's lymphoma [3] in human epidemiological studies.

Although studies of pesticide exposure among farmers and their families are confounded by exposure to multiple pesticides, there is a large and compelling body of data that demonstrates the link between occupational exposure to herbicides and insecticides and non-Hodgkin's lymphoma. [4]

Studies of farmers who worked with 2,4-D found a link between exposure to this herbicide and suppressed immune function, [5] lower sperm count, [6] and a greater risk of Parkinson's disease. [7]

These findings from human studies, whether small-scale, pilot studies or large cohort studies, point out significant risks from 2,4-D to human health even for the relatively healthy adults who work in agricultural jobs.

Such risks would be much higher for young children, especially young children in residential communities, schools, and daycare centers near the 2,4-D-sprayed fields.

No toxicity tests for simulataneous exposure

Also worrisome is the fact that the manufacturer did not conduct any toxicity tests for simultaneous exposure to the combination of 2,4-D and glyphosate, which could pose a much higher human and environmental toxicity risk than either herbicide alone.

EPA acknowledges that "there could be additional toxicological effects (synergistic or additive) because of the presence of two herbicides." [8]

Yet, the Agency disregarded these data gaps and both human and environmental toxicity concerns in its proposal to register the Enlist DuoTM herbicide.

Widespread contamination would follow

If the EPA were to approve Dow's application for 2,4-D-glyphosate herbicide to be used on 2,4-D-resistant crops, USDA estimates at least a tripling of use of 2,4-D by 2020 compared to the present amounts used annually for agriculture in the United States. [9]

The increase in 2,4-D spraying on corn and soybean fields would lead to pollution of food and water and increased drift of 2,4-D from the fields into nearby residential areas.

The Dow Chemical Company claims that their 2,4-D choline salt formulation has low volatility and low drift. However, the large-scale, blanket spraying that has become standard practice with genetically engineered crops would make herbicide drift from sprayed fields into nearby residential areas and ecosystem habitats highly likely to occur.

In addition to putting human health at risk, increased 2,4-D spraying would harm the already-vulnerable ecosystems in intensely farmed regions of the United States; affect dozens of endangered species; and potentially contribute to the decline of pollinators and honeybees.

EPA itself has identified these likely outcomes of 2,4-D spraying in the agency's ecological risk assessment for 2,4-D. Such direct and indirect effects of 2,4-D would have significant negative economic consequences.

More herbicide-resistant weeds

Finally, increased 2,4-D application is likely to accelerate and exacerbate the evolution of yet more 2,4-D resistant weeds. [10] This pattern is known as the 'pesticide treadmill' when farmers end up using larger amounts of increasingly toxic chemicals to control herbicide-resistant weeds eventually requiring the use of different pesticides.

Decades of research have continuously demonstrated the risks of using 2,4-D, a notoriously toxic herbicide. Allowing large-scale 2,4-D spraying in combination with 2,4-D-tolerant genetically engineered crops would worsen the problem.

We urge the EPA to do the right thing and deny the approval of the new mixtures of 2,4-D and glyphosate in order to protect human and environmental health.

See the original letter here as PDF.

References

Owen MD. Weed species shifts in glyphosate-resistant crops. Pest Manag Sci. 64(4): 377-87. and Owen MD, Young BG, Shaw DR, Wilson RG, Jordan DL, Dixon PM, Weller SC. 2011. Benchmark study on glyphosate-resistant crop systems in the United States. Part 2: Perspectives. Pest Manag Sci. 67(7): 747-57. Goldner WS, Sandler DP, Yu F, Shostrom V, Hoppin JA, Kamel F, LeVan TD. 2013. Hypothyroidism and pesticide use among male private pesticide applicators in the agricultural health study. J Occup Environ Med. 55(10): 1171-8. Miligi L, Costantini AS, Veraldi A, Benvenuti A; WILL, Vineis P. Cancer and pesticides: an overview and some results of the Italian multicenter case-control study on hematolymphopoietic malignancies. Ann N Y Acad Sci 1076:366-77, 2006. Schinasi L, Leon ME. 2014. Non-Hodgkin lymphoma and occupational exposure to agricultural pesticide chemical groups and active ingredients: a systematic review and meta-analysis. Int J Environ Res Public Health 11(4): 4449-527. Faustini A, Settimi L, Pacifici R, Fano V, Zuccaro P, Forastiere F. 1996. Immunological changes among farmers exposed to phenoxy herbicides: preliminary observations. Occup Environ Med. 53(9): 583-5. Lerda D, Rizzi R. 1991. Study of reproductive function in persons occupationally exposed to 2,4-dichlorophenoxyacetic acid (2,4-D). Mutat Res. 262(1): 47-50. Tanner C, Ross G, Jewell S, Hauser R, Jankovic J, Factor S, Bressman S, Deligtisch A, Marras C, Lyons K, Bhudhikanok G, Roucoux D, Meng C, Abbot R, Langston W. 2009. Occupation and Risk of Parkinsonism. Arch. Neurol. 66(9): 1106-13. EPA (U.S. Environmental Protection Agency). 2013. EFED (Environmental Fate and Effects Division) Environmental Risk Assessment of Proposed Label for Enlist (2,4-D Choline Salt), New Uses on Soybean with DAS 68416-4 (2,4-D Tolerant) and Enlist (2,4-D + Glyphosate Tolerant) Corn and Field Corn. Docket EPA-HQ-OPP-2014-0195. USDA (U.S. Department of Agriculture). 2013. Dow AgroSciences Petitions (09-233-01p, 09-349-01p, and 11-234-01p) for Determinations of Nonregulated Status for 2,4-D-Resistant Corn and Soybean Varieties. Draft Environmental Impact Statement. Mortensen, DA, JF Egan, BD Maxwell, MR Ryan, and RG Smith. 2012. Navigating a Critical Juncture for Sustainable Weed Management. BioScience, 62: 75-84.

Signatories

Toni Bark, M.D., MHEM, LEED AP

Founder and Medical Director

Center for Disease Prevention and Reversal

Charles Benbrook, Ph.D.

Research Professor

Center for Sustaining Agriculture and Natural

Resources

Washington State University

Alison Bleaney, M.B., Ch.B., FACRRM

Medical Practitioner

National Toxics Network, Tasmanian Environmental

Health Network, Doctors for America

David O. Carpenter, M.D.

Director

Institute for Health and the Environment at Albany

Lynn Carroll, Ph.D.

Senior Scientist

TEDX, The Endocrine Disruption Exchange

Margaret Christensen, M.D., FACOG

Adjunct Faculty, President

Institute for Functional Medicine, Christensen Center

for Whole Life Health

Theo Colborn, Ph.D.

President Emeritus

TEDX, The Endocrine Disruption Exchange

Johanna Congleton, MSPH, Ph.D.

Senior Scientist

Environmental Working Group

Martin Donohue, M.D., FACP

Adjunct Associate Professor; Member; Senior

Physician

School of Community Health, Portland State

University; Social Justice Committee & Board of

Advisors, Physicians for Social Responsibility;

Internal Medicine, Kaiser Sunnyside Medical Center

Diane Drum, R.N., AE-C

Multnomah County Environmental Health

Mary Eubanks, Ph.D.

Adjunct Professor

Dept. of Biology, Duke University

Elizabeth Frost, M.D.

Medical Practitioner

Hennepin County Medical Center (HCMC)

Robert M. Gould, M.D.

President

San Francisco Bay Area Chapter, Physicians for

Social Responsibility

Michael Hansen, Ph.D.

Senior Scientist

Consumers Union

Carol Kwiatkowski, Ph.D.

Executive Director

TEDX, The Endocrine Disruption Exchange

Philip J. Landrigan, M.D.

Dean for Global Health

Ethel H. Wise Professor and Chairman

Department of Preventive Medicine

Professor of Pediatrics

Director, Children's Environmental Health Center

Icahn School of Medicine at Mount Sinai

Chensheng (Alex) Lu, Ph.D.

Associate Professor of Environmental Exposure

Biology

Dept. of Environmental Health, Harvard School of

Public Health

Rob McConnell, M.D.

Professor of Preventative Medicine

University of Southern California

Margaret Mellon Ph.D., J.D.

Science Policy Consultant

Mellon Associates

Gretel Munroe, M.S., MSH, R.D.

Raymond Richard Neutra, M.D., DrPH

Retired Chief of Division of Environmental and

Occupational Disease Control

California Dept. of Public Health

John A. Patterson, M.D., MSPH

Associate Professor

Dept. of Family and Community Medicine, University

of Kentucky College of Medicine

Jerome A. Paulson, M.D., FAAP

Medical Director for National and Global Affairs

Children's National Health System

Warren Paul Porter, Ph.D.

Professor of Zoology, Professor of Environmental

Toxicology, Invited Affiliate Faculty Member,

Engineering Physics

University of Wisconsin, Madison

Julia Quint, Ph.D.

Research Scientist and Former Chief

Hazard Evaluation System and Information Service,

California Department of Public Health (Retired)

James Roberts, M.D., MPH

Associate Professor of Pediatrics

Medical University of South Carolina

Johanna Rochester, Ph.D.

Research Associate

Hazard Evaluation System and Information Service,

California Department of Public Health (Retired)

Kenneth Rosenman, M.D., FACE, FACPM

Professor of Medicine, Chief of the Division of

Occupational and Environmental Medicine

Michigan State University

Ricardo J. Salvador, Ph.D.

Director and Senior Scientist

Union of Concerned Scientists

Jennifer Sass, Ph.D.

Senior Scientist, Professional Lecturer

Natural Resources Defense Council, George

Washington University

Shilpa P. Saxena, M.D.

President

SevaMed Institute, PA

David Shubert, Ph.D.

Professor

Salk Institute for Biological Studies

Sandra Steingraber, Ph.D.

Distinguished Scholar in Residence

Dept. of Environmental Studies and Science

Ithaca College

Robin M. Whyatt, DrPH

Professor of Environmental Health Sciences

Colombia Center for Children's Environmental Health

Marisa C. Weiss, M.D.

President and Founder

Breastcancer.org

The signers of this letter have done so in their personal capacities. Institutional affiliations are provided only for identification purposes and do not imply any institutional position.