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What is 2,4-D?

2,4-Dichlorophenoxyacetic Acid (2,4-D) is a chlorinated phenoxy herbicide. 2,4-D has been shown to cause cellular mutations which can lead to cancer. This mutagen contains dioxins, a group of chemicals known to be hazardous to human health and to the environment (1,2).

How does 2,4-D work?

2,4D is a growth inhibitor. It is absorbed into a plant through the plant’s surface. The weed killer circulates through all parts of the plant and causes abnormal growth blocking the passage of liquids and nutrients. Subsequently, the roots starve and the plant dies (3).


Side effects of 2,4-D

The Environment

2,4-D is a moderately persistent chemical with a half-life between 20 and 200 days. Unfortunately, the herbicide does not affect target weeds alone. It can cause low growth rates, reproductive problems, changes in appearance or behaviour, or death in non-target species.

Additionally, the spraying of 2,4-D often, contaminates ground water systems. (About 91.7% of 2,4-D will eventually end up in water (4). This contamination threatens the vegetation and the animal life that consumes it. The chemical will also be carried by run-off into the local river systems, thereby jeopardizing the health of aquatic life as well.

In the urban setting, it has been proven that households using 2,4-D put their dogs at twice the risk of developing canine malignant lymphoma (5).

Human Health

Documented health problems relate to 2,4-D include reproductive damage (I.e. sterility), respiratory difficulties, atrophy, nausea, loss of appetite, skin rashes, eye irritation, and chronic headaches (6). Non-Hodgkins lymphoma has also been associated with 2,4-D exposure (7). Furthermore, there is evidence of teratogenicity (birth defects) and mutagencity (mutation of cells) provided by studies involving 2,4-D and lab animals (8).

Workers applying chlorinated phenoxy herbicides frequently have nervous system disorders, are exposed to a higher risk of soft tissue sarcoma, and show symptoms of hormonal and internal organ irregularities (9,10).

Regulatory Status

With the initial development of pesticides, their use was expansive. Only in the past two decades has it been openly acknowledged (by governments and industry) that these chemicals are poisonous to humans and their environment. Since 1980, Agriculture Canada and Agri-Food Canada have been reviewing the regulatory status of 2,4-D. In 1981, a limit was set on the allowable level of dioxins in 2.4-d products. The following year, Agriculture Canada defined more precise dosage ranges and acceptable use patterns.

Most recently, Health Canada has appropriated pesticide regulating responsibilities from Agriculture Canada. Currently the Pest Management Regulatory Agency (PMRA), a division of Health Canada, is working on a Label Improvement Program for 2.4-D designed to reduce exposures to the hazardous chemical. Part of this program also aims to “harmonize” with the policies of the U.S. Environmental Protection Agency (EPA).

The registration for most of the 38 different formulations of 2,4-D is up for renewal (11). Regrettably, there are no established channels for public participation it the pesticide regulating process. The chemical industry, on the other hand, can place a significant amount of pressure on policy makers, offering jobs, investments, and revenue as incentives for pesticides product approval.

Who uses 2,4-D?

The pesticide is used primarily by cereal crop producers. The forestry industry uses 2,4-D to suppress the growth of hardwoods and undergrowth in conifer plantations. Another application of 2,4-D occurs along major rights-of-ways (i.e. railway tracks) to control brush. In urban areas 2,4-D is applied to control broad leafed weeds such as dandelions, ragweed, and poison ivy (12). It is the active ingredient in readily available weed control mixtures, for example, killex.

Ethical Considerations

The continued use of 2,4-D products is promoted by the chemical manufacturers who profit from its continued use. Given the dangerous nature of the weed killer, this is a clear example of maximizing returns to shareholders at the expense of the well-being of the biosphere.


References

1. Associate committee on Scientific Criteria for Environmental Quality; Subcommittee on Pesticides and Industrial Organic Chemicals. “2,4-D Some Current Issues” NRCC No. 20647. National Research Council of Canada, 1994. Pp.23
   
   
2. Littorin, M “Dioxins in Blood from Swedish Phenoxy Herbicide Workers.” In Lancet Vol.344 (8922), August 27,19994 pp.611-612.
   
   
3. Environment Canada Fact Sheet, “Pesticides :2,4-D, MCPA, Dichlorprop, Mecoprop”
   
   
4. Gopher://ecosys.drdr.VirtualLibrary/gen/ toxins/2%2C4-D
   
   
5. Hayes, Howard M, et al. “Case-Control Study of Canine Malignant Lymphoma: Positive Association With Dog Owner’s Use of 2,4-Dichlorophenoxyacetic Acid Herbicides” In Journal of the National Ccancer Inctitute. Vol.83 (17) September 1, 1991. Pp.1226-1231
   
   
6. Gopher://ecosys.drdr.VirtualLibrary/gen/ toxins/2%2C4-D
   
   
7. Kogevinas, M. “ Soft Tissue Sarcoma and non-Hodgkins Lymponmain Workers exposed to phenoxy-herbicides, chlorophenols, and dioxins – 2 nested case studies.” In Epidemiology. Vol.6 (4) July, 1995. Pp.396-402
   
   
8. Environment Canada Fact Sheet, “Pesticides :2,4-D, MCPA, Dichlorprop, Mecoprop”
   
   
9. Kogevinas, M. “ Soft Tissue Sarcoma and non-Hodgkins Lymponmain Workers exposed to phenoxy-herbicides, chlorophenols, and dioxins – 2 nested case studies.” In Epidemiology. Vol.6 (4) July, 1995. Pp.396-402
   
   
10. Associate committee on Scientific Criteria for Environmental Quality; Subcommittee on Pesticides and Industrial Organic Chemicals. “2,4-D Some Current Issues” NRCC No. 20647. National Research Council of Canada, 1983. Pp. 29,55.
    
    
11. Interdepatmental Executive Committee on Pest Management. “2,4-D Re-evaluation Update and Label Improvement Program.” Note to CAPCO C94-08. November 23, 1994.
    
    
12. ibid
    

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