March 1996

2,4-D: The Rest of the Story

David M. Kopec, Extension Turfgrass Specialist

This is an up date on the continuing saga about the re-registration of 2,4-D.

First released in 1947 as the first selective herbicide to control weeds without damaging crop plants, 2,4-D has been a work horse in practical weed control in all of agriculture, including turf.

In 1988, the U.S. Congress amended FIFRA (Federal Insecticide Fungicide and Rodenticide Act) in such a way so that pesticides registered before November of 1984 be re-registered. This was done so that older pesticides meet the new criteria as newly developed pesticides do.

An industry task force was formed in 1988 to coordinate data testing to meet these new requirements. The 2,4-D task force outlined about 270 new studies addressing toxicology, environmental studies, environmental fate, chemical residue and other tests. Others studies due to the EPA by December 1995 included chronic (long term) toxicity, field dissipation and crop residue reports. The Task force summary completed from this research was recently given at a Chicago seminar. Briefly, the Task Force concluded that 2,4-D;

1. Is not linked to genetic damage or tumor induction. Nor is it related to reproductive or developmental problems.

2. Hopefully, with low toxicity levels and low direct exposure , 2,4-D will meet a "no unreasonable adverse affects" category decision, as described in FIFRA.

However, the National Cancer Institute (NCI) has raised concerns about potential links between the herbecide 2,4-D and non Hodgkins lymphoma (NHL) among farm workers. This disease is group of diseases that are classified as immune system disorders, collectively.

The 1986 Kansas study showed some relationship between NHC and pesticide use, which includes 2,4-D. However the frequency and use amounts of 2,4-D was never asked or determined in this study. So 2,4-D was "lumped" with all other pesticides. This fact was acknowledged six months later in a scientific journal, as a formal recognition of this fact by the NCI.

Six different panels of epidemiologist and toxicologists indicated (same conclusions) that the herbecide 2,4-D does not cause HDL. However, an EPA appointed Panel (Science Advisory Board) believes that the existing data may be inconclusive for 2,4-D and NHL, and perhaps further studies are needed.

The EPA should render its re-registration decision on 2,4-D by 1997 in a document called the Re-registration Eligibility Document (RED). This should contain the EPA answer relative to its decision (re-registration yes or no), why it made the decision, and any need for additional information.

Remember, when using 2,4-D or any pesticide, follow label directions noting the maximum use rate, number of applications you can make, under what conditions, and the use of personal protective equipment. [Source=Access Pesticide Newsletter Vol XXI No.2, Feb 1996]

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