ABSTRACT

2,4-Dichlorophenoxyacetic acid (2,4-D) is released into the environment through its use in herbicide formulations and as a hydrolysis product of 2,4-D esters or from spills. 2,4-D enters the environment mainly through its direct application as a systemic herbicide. The rate of degradation is affected by several conditions, especially the concentrations of 2,4-D and water content, temperature and the organic content of soil and the status of preexposure of the soil to 2,4-D or its esters. The primary source of 2,4-D in air is spray applications of the herbicide or its mixture. The rate will depend on a number of factors including presence of acclimated organisms, nutrient levels, temperature and concentration of 2,4-D. A half-life of 50 min was reported for 2,4-D in water irradiated at 254 nm with products listed as 2,4-dichlorophenol, 4-chlorocatechol, 2-hydroxy-4-chlorophenoxyacetic acid, 1,2,4-benzenetriol and polymeric humic acids. Agricultural workers may be exposed to 2,4-D compounds during spraying operations using herbicides containing this chemical.