EWG's Tap Water Database — 2019 UPDATE



Sun Valley Gid

2,4-D (2,4-dichlorophenoxyacetic acid) is a herbicide that can be applied directly to GMO corn and soy plants engineered to withstand this toxic chemical. Americans' exposures to 2,4-D from food and drinking water will likely increase in years to come as farmers plant more of these GMO crops. Read More.

2,4-D is an endocrine disruptor that interferes with thyroid hormones. The International Agency for Research on Cancer classifies 2,4-D as possibly carcinogenic to humans. In occupational studies, farmers exposed to 2,4-D tended to have higher incidences of damaged and malformed sperm. Laboratory animals exposed to 2,4-D during gestation are born underdeveloped and are more likely to have birth defects.





Samples exceeding legal limit (MCL)


Samples exceeding
health guidelines

Testing results - average by year

YearAverage resultSamples takenDetectionsRange of results
20150.0147 ppb192ND - 0.140 ppb
20160.00719 ppb321ND - 0.230 ppb
20170.0301 ppb522ND - 0.180 ppb

ppb = parts per billion

State and national drinking water standards and health guidelines

EWG Health Guideline 20 ppb

The EWG Health Guideline of 20 ppb for 2,4-D was defined by the California Office of Environmental Health Hazard Assessment as a public health goal, the level of a drinking water contaminant that does not pose a significant health risk. This health guideline protects against harm to internal organs.

EPA Maximum Contaminant
Level (MCL) 70 ppb

The legal limit for 2,4-D, established in 1991, was based on toxicity studies in laboratory animals conducted in the 1980s. This limit may not fully protect against harm to the nervous system, harm to the thyroid, and hormone disruption.

ppb = parts per billion

All test results

Date Lab ID Result