What is 2,4-D?
2,4-Dichlorophenoxyacetic acid, more commonly referred to as 2,4-D, is one of the most widely used herbicides in the world to control weeds in agricultural crops, forests and turf grass as well as invasive species in environmentally sensitive areas.
Given its use over 65 years, very few substances have been subjected to the extensive examination and review that 2,4-D has withstood, and as a result, more is known about 2,4-D than almost any other chemical on the planet. As well, few scientific innovations have done as much to increase food production throughout the world as 2,4-D.
Are pesticides like 2,4-D adequately researched?
In addition to being the most widely used agricultural herbicide worldwide, 2,4-D was the first selective herbicide developed; meaning, 2,4-D controls weeds in agricultural production without harming the crop. Over six decades, this has resulted in an enormous amount of research on 2,4-D across the globe.
More is known about 2,4-D and how it works than almost any other crop protection tool. The toxicology database alone exceeds 4,000 peer-reviewed, published studies, plus hundreds of scientific studies that manufacturers of 2,4-D must provide to regulatory agencies throughout the world so registrations of products containing 2,4-D are kept current.
There are now more than 160 peer-reviewed, published epidemiologic (human) studies pertinent to 2,4-D. Notably, the industry research Task Force has taken the additional step of publishing the research data submitted to regulators in peer-reviewed journals.
Soil dissipation of 2,4-D is well understood. The recent data from 30 soil dissipation studies on various soil types around North America illustrate a median 2,4-D half-life of 5.6 days.
2,4-D is classified as non-persistent to slightly persistent in soil and natural water because of rapid microbial break down.
I have heard regulatory agencies base their decisions on ‘secret studies’ paid for by the pesticide industry, is this true?
The Task Force did not conduct a single research study of the more than 300 Good Laboratory Practices (GLP) studies required by the EPA and the PMRA for the reregistration/re-evaluation of the herbicide 2,4-D. Regulatory decisions regarding 2,4-D are based on an enormous body of research that has been conducted by some 30 EPA GLP accredited laboratories in concert with studies and reports published in scientific journals, as well as other foreign nations’ and international organizations’ reviews.
Regulators carefully review all studies for GLP compliance and any intentional GLP violation (such as false or misleading information/data about the health or environmental risks) is a violation of federal law. These laws are enforced, so both the company responsible and the laboratory doing the work take GLP guidelines very seriously.
In summary, regulators do not base any registration decisions on secret studies. Importantly, the industry research Task Force has taken the additional step of publishing the research data submitted to regulators in peer-reviewed journals.
As part of our initiative, the Task Force works closely with regulatory agencies to gather the most up to date information and share the most pertinent findings with the general public.
What is the EPA’s position on 2,4-D and cancer?
Worldwide, no pesticide regulatory agency classifies 2,4-D as a human or animal carcinogen.
In issuing the Order Denying NRDC's Petition to Revoke Tolerances in April 2012, the EPA stated:
“A part of this cancer assessment was the review of data bearing on 2,4-D’s potential mutagenicity. EPA has consistently found that these data do not support classification of 2,4-D as a carcinogen. This view was concurred in by the Joint Committee of Science Advisory Board (SAB) and the Scientific Advisory Panel (SAP)”
Some reports claim children are more susceptible to pesticides due to their behavior and unique physiological characteristics, is this true?
Specific risk assessments for children, taking into consideration their unique physiology, diets, behaviors and play-habits (including their body weight and hand-to-mouth contact while playing on treated grass), are undertaken before a pesticide is granted a registration in both the United States and Canada.
Pesticides are often found in the blood and urine of children, what does this mean?
It is normal to find trace amounts of many chemicals in tissues or fluids when an individual has been exposed to them. However, exposure does not mean there will be any associated negative health effects, particularly if the levels are very small as they most often are. With the advancement of technology, these measurements are commonly assessed in the parts per trillion.
To put this into context:
one part per trillion is the equivalent of 1 second in the span of 32,000 years.
The presence of a trace amount of any chemical or compound, whether it is from cosmetics, tap water, soaps and shampoos or herbicides like 2,4-D, is very common and does not necessarily equate to any potential health consequenses.
Does 2,4-D cause cancer in dogs?
Multiple studies, including the 1999 study conducted at the School of Veterinary Medicine at Michigan State University, conclude that there is no correlation between 2,4-D and Canine Malignant Lymphoma (CLM). Regulatory decisions around the world confirm that 2,4-D is not an animal carcinogen.
Homeowners should continue to use herbicides in accordance with label directions and restrict access during and immediately following the application of products containing 2,4-D to maximize its efficiency and limit potential exposure.
Is 2,4-D an endocrine disruptor?
It is not. The EPA considered this question in both its 2005 decision and its most recent response to the NRDC petition. In both instances the EPA determined that 2,4-D was not an endocrine disruptor. Most recent, in consideration of a number of studies cited by the NRDC, the EPA stated:
“In sum, the data cited by NRDC, Beyond Pesticides, and NYDOH do not support changing the quantitative endpoints for assessing the risk posed by 2,4-D for potential endocrine effects given the equivocal results in the studies cited and/or the high doses involved in the studies.”
Did the EPA consider alternatives to 2,4-D?
In considering the NRDC petition and the submissions from many interveners, the EPA was asked to consider alternatives. Some groups assert that the evaluation should include a comparison of environmental fate characteristics, application rates and methods, efficacy, and risks to public health and non-target organisms. In responding, the EPA stated:
“Generally, the Agency does not assess alternatives where it has not identified any risks of concern. Where a pesticide has no risks of concern, it is unnecessary to consider the risk profiles of alternative pesticides in determining whether the pesticide being assessed will cause unreasonable adverse effects on the environment. Further, EPA may not deny registration to a pesticide because it is non-essential.”
What did Health Canada determine about 2,4-D with its most recent decision?
After years of analyzing all the pertinent science and considering the public’s input in 2005 and again in 2007, Health Canada’s Pest Management Regulatory Agency (PMRA) has determined that 2,4-D may be used safely according to label directions. With specific regard to use on lawns, the PMRA stated:
“Health Canada has determined that 2,4-D meets Canada’s strict health and safety standards. Risks to homeowners and their children from contact with treated lawns and turf are not of concern.”
Additionally, Health Canada consulted with an independent Science Advisory Panel comprised of government and university researchers in toxicology, epidemiology and biology. The panel agreed with PMRA’s assessment that 2,4-D can be used safety when label directions are followed.
Homeowners are advised to limit exposure to lawns during and following the application of products containing 2,4-D, as instructed by label directions.
Is exposure to the odor of 2,4-D hazardous?
Pure 2,4-D is odorless. Odor associated with the application of 2,4-D comes from a small amount of the primary breakdown product, 2,4-dichlorophenol (DCP).
Another odor may come from a small amount of dimethylamine, a neutralizing agent of the 2,4 D formulation. Both of these compounds possess extremely low toxicity as a vapor, though low levels can be quite odorous. Government agencies have indicated low toxicological concern for inhalation of 2,4-D.
Odor exposure of 2,4-D is not of toxicological concern.
Why is 2,4-D banned in Sweden and Denmark?
It is not. In 2011, national regulators in Sweden and Denmark approved uses for 2,4-D after evaluating the modern scientific data package.
With over 65 years of use and demonstrated value, 2,4-D continues to be one of the most important herbicides for farmers, homeowners and land managers across the globe.
Are bystanders to turf applications exposed to 2,4-D?
Several researchers at the University of Guelph, in Canada, have completed studies on human exposure to applications of 2,4-D for the Ontario Ministry of the Environment. These studies show the highest observed exposures for homeowners and commercial applicators were well below the lifetime ADI (acceptable daily intake) as established by the World Health Organization.
The most recent research demonstrates that there were no detectable exposures for the bystanders who reside in homes of homeowner or commercially treated lawns or for barefoot, barelegged bystanders who actively walked or sat on turf grass for one hour on the day of spraying.
Should 2,4-D be a concern for groundwater contamination?
No. The rapid breakdown of 2,4-D minimizes the potential for movement in soil, and greater than 90 – 95 percent dissipates in the top six inches of soil.
Eventually 2,4-D breaks down to CO2 and is integrated into other carbon compounds in the soil. Any findings of 2,4-D in ground water have been extremely rare. These have been attributed to spot contamination or spills near water wells or unique soil conditions with high rainfall or irrigation shortly following application.