The Agency for Toxic Substances and Disease Registry has published a 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. Other individuals may be exposed to the chemical while walking or playing on recently treated areas. 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. ATSDR’s “Tox Profiles” characterize the toxicological and adverse health effects information for hazardous substances. For a full list of toxic substances with published profiles, visit the agency's .