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Summary of the Public Health Goal for 2,4-Dichlorophenoxyacetic Acid (2,4-D)

A Public Health Goal (PHG) of 70 ppb is developed for 2,4-dichlorophenoxyacetic acid (2,4-D) in drinking water. This report provides a brief discussion of the herbicide 2,4-D and its amine, esters and salts to support the determination of our PHG of 70 ppb based on a no-observed-adverse-effect level (NOAEL) of 1 mg/kg-day for hematologic, renal and liver effects in 90-day and chronic rat studies. This PHG is identical to the current state Maximum Contaminant Level (MCL), established in 1994 on the basis of the Recommended Public Health Level (RPHL) of 70 ppb proposed by the Office of Environmental Health Hazard Assessment (OEHHA) in 1991. This level is also consistent with the U.S. Environmental Protection Agency’s (U.S. EPA’s) MCL and MCL Goal (MCLG) of 70 ppb set in 1991. Therefore, OEHHA adopts a PHG of 0.07 mg/L (70 ppb) for 2,4-D in drinking water.