July 23, 2020

New Profile for Herbicide 2,4-D Summarizes Toxicological Information

The Agency for Toxic Substances and Disease Registry has published a final toxicological profile for the chemical 2,4-dichlorophenoxyacetic acid (2,4-D), an active ingredient in herbicides used worldwide. According to ATSDR, workers may have higher exposures to 2,4-D during tasks that involve handling and applying it to weeds. Others may be exposed to the chemical while walking or playing on recently treated areas. The agency notes that people are unlikely to be exposed to high levels of 2,4-D in food, water, or soil. ATSDR explains that a few studies of farmers or professional applicators of herbicides containing 2,4-D—workers who are exposed to higher amounts of the chemical than most people—found increased risk of cancers of the lymphatic system, especially non-Hodgkin lymphoma. The toxicological profile also describes harmful effects on the blood, livers, kidneys, and thyroid glands of laboratory animals that were given large oral doses of 2,4-D. People who purposely or accidentally swallowed large amounts of the chemical have exhibited respiratory and nervous system effects.

In a monograph published in 2018, the International Agency for Research on Cancer classified 2,4-D as possibly carcinogenic to humans based on “inadequate evidence” of its carcinogenicity in humans and “limited evidence” in experimental animals. According to EPA, “2,4-D generally has low toxicity for humans, except certain acid and salt forms can cause eye irritation.”

ATSDR’s “Tox Profiles” characterize the toxicological and adverse health effects information for hazardous substances. Each peer-reviewed profile identifies and reviews the key literature that describes a substance's toxicological properties. Information on the potential for human exposure; chemical and physical properties; regulations and guidelines; and production, import, use, and disposal can also be found in ATSDR’s toxicological profiles. A full list of toxic substances with published profiles is available on the agency’s website.