Chronic dietary toxicity/oncogenicity studies on 2,4-dichlorophenoxyacetic acid in rodents

Fundam Appl Toxicol. 1996 Oct;33(2):166-72. doi: 10.1006/faat.1996.0154.


Forms of 2,4-dichlorophenoxyacetic acid (collectively known as 2,4-D) are herbicides used to control a wide variety of broadleaf and woody plants. Doses in the 2-year chronic/oncogenicity rat study were 0, 5, 75, and 150 mg/kg/day. The chronic toxicity paralleled subchronic findings, and a NOEL of 5 mg/kg/day was established. A slight increase in astrocytomas observed (in males only) at 45 mg/kg/day in a previously conducted chronic rat study was not confirmed in the present study at the high dose of 150 mg/kg/ day. Doses in the 2-year mouse oncogenicity studies were 0, 5, 150, and 300 mg/kg/day for females and 0, 5, 62.5, and 125 mg/ kg/day for males. No oncogenic effect was noted in the study. In summary, the findings of these studies indicate low chronic toxicity of 2,4-D and the lack of oncogenic response to 2,4-D following chronic dietary exposure of 2,4-D in the rat and mouse.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • 2,4-Dichlorophenoxyacetic Acid / toxicity*
  • Animals
  • Carcinogenicity Tests
  • Diet*
  • Female
  • Herbicides / toxicity*
  • Male
  • Mice
  • Organ Size / drug effects
  • Rats
  • Rats, Inbred F344
  • Species Specificity


  • Herbicides
  • 2,4-Dichlorophenoxyacetic Acid