Oxidative Stress as a Possible Mechanism of Toxicity of the Herbicide 2,4- Dichlorophenoxyacetic Acid (2,4-D)

Chlorophenoxy herbicides are widely used in agriculture and forestry, for the control of broad-leaved weeds in pastures, cereal crops, as well as along public rights of way. Structurally, these herbicides consist of a simple aliphatic carboxylic acid moiety attached to a chlorine-substituted aromatic ring via an ether linkage. One of the most commonly used herbicides of this type is 2,4-dichlorophenoxyacetic acid (2,4-D) (Fig. 1). In congruence with the similitude between its molecular structure and that of the plant hormone indole-acetic acid, 2,4-D acts as a plant growth regulator that can interfere with normal hormonal action and plant growth (Munro et al., 1992).