2,4-Dichlorophenoxy Acid (2,4-D)

2,4-Dichlorophenoxyacetic acid (2,4-D), a chlorinated phenoxy compound and is the active ingredient in a number of herbicide formulas. 2,4-D kills plants by causing uncontrolled cell division in vascular tissue. There are multiple chemical forms of 2,4-D including salts, esters and an acid form. The toxicity of 2,4-D depends on its form. Formulations also impact how 2,4-D changes in the environment and how it affects the environment.

2,4-D has been used in the United States since the 1940s, and there are over 1,000 products with 2,4-D in them. These products may be liquids, dusts, or granules. Major uses of 2,4-D in agriculture are on cereal crops such as wheat, corn, oats, rye, and barley, and the cane crops. It is also used in domestic lawn control on dandelions and other broadleaf weeds. Other uses include the control of aquatic weeds, some woody vegetation, and site preparation and conifer release in forests.

Agent Orange, the herbicide widely used during the Vietnam War, contained 2,4-D. However, the controversy regarding health effects were centered around the 2,4,5-T component of the herbicide and its contaminant, dioxin.

Exposure

The general population may be exposed during the 2,4-D application process, direct contact with agricultural and residential areas after application and by consuming food or drinking water contaminated with 2,4-D. It is absorbed rapidly via oral and inhalation routes. It is not absorbed well through the skin. 2,4-D does not build up in tissues once it is in the body. In fact more than 75% of absorbed 2,4-D leaves the body in the first 4 days after exposure.

EPA Regulatory Guidelines

Health Effects

Pure 2,4-D has low toxicity if eaten, inhaled or comes into contact with the skin. No occupational studies have found signs or symptoms following exposure to 2,4-D under normal usage. Symptoms of acute oral exposure to 2,4-D include vomiting, diarrhea, headache, confusion, aggressive or confused behavior, kidney failure, and skeletal muscle damage. These cases have been mostly associated with suicide attempts. Some cases of 2,4-D ingestion resulted in death. Symptoms following dermal exposure may include irritation, and inhalation exposure may lead to coughing and burning sensations in the upper respiratory tract and chest. Prolonged exposure may result in dizziness.

The International Agency for Research on Cancer (IARC) released the following information regarding 2,4-D as a carcinogenic to humans.

Animals can also be exposed to 2,4-D if they come into direct contact with an area after application. Dogs may be more sensitive to 2,4-D than other animals. Dogs that have been in contact with 2,4-D developed vomiting, diarrhea, loss of appetite, lethargy, drooling, staggering and convulsions.

Sources of additional information

Agency for Toxic Substances and Disease Registry (ATSDR)

Centers for Disease Control and Prevention (CDC)

U.S. Environmental Protection Agency (EPA)

National Pesticide Information Center (NPIC)

Last Update: May 9, 2016