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EWG's Tap Water Database — 2021 UPDATE

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Atrazine

Metropolitan Utilities District

Atrazine is a herbicide commonly detected in drinking water that comes from cornfield and other agricultural runoff. It is a hormone disrupter that harms the male and female reproductive systems of people and wildlife. Read More.

Federal laws allow up to 3 parts per billion of atrazine in treated tap water. Water suppliers average atrazine measurements collected over a year, which means that the reported values underestimate intense spikes of elevated exposures during the periods in late spring and early summer when atrazine is applied in large amounts on farm fields.

Human epidemiological studies suggest that federal standards for atrazine are insufficient to protect public health. In 1999 the California Office of Environmental Health Hazard Assessment set a public health goal of 0.15 parts per billion for atrazine in drinking water, based on a study finding increased rates of breast cancer in rats exposed to the chemical. California’s legal maximum for atrazine in tap water is 1 ppb.

Click here to read more about atrazine.

 

40

Samples

0

Samples exceeding legal limit (MCL)

1

Samples exceeding
health guidelines

Testing results - average by year

 
YearAverage resultSamples takenDetectionsRange of results
2013N/A00N/A
2014ND40ND
20150.00838 ppb161ND - 0.134 ppb
2016ND30ND
2017ND40ND
2018ND110ND
2019ND20ND

ppb = parts per billion

State and national drinking water standards and health guidelines

EWG Health Guideline 0.1 ppb

The EWG Health Guideline of 0.1 ppb for atrazine was defined by EWG based on epidemiological studies of human exposure to atrazine in drinking water.. This health guideline protects against harm to the developing fetus, harm to the reproductive system and hormone disruption.

EPA Maximum Contaminant
Level (MCL) 3 ppb

The legal limit for atrazine, established in 1991, was based on a toxicity study in laboratory animals conducted in the 1980s. This limit does not fully protect against harm to the reproductive system, harm to the developing fetus, and hormone disruption.

ppb = parts per billion

All test results

Date Lab ID Result
2014-04-14293528ND
2014-04-28295610ND
2014-04-28295611ND
2014-04-28295612ND
2015-04-20353921ND
2015-04-20353920ND
2015-04-203539220.134 ppb
2015-06-08357039ND
2015-06-08357035ND
2015-06-08357034ND
2015-06-08357033ND
2015-06-09357037ND
2015-06-09357038ND
2015-07-14374240ND
2015-08-10375179ND
2015-08-10375178ND
2015-08-10375177ND
2015-08-10375176ND
2015-08-10375180ND
2015-08-10375175ND
2016-04-18ND
2016-04-18ND
2016-04-18ND
2017-04-17ND
2017-04-17ND
2017-04-17ND
2017-07-11ND
2018-04-24543626ND
2018-04-24543625ND
2018-04-24543624ND
2018-06-05545297ND
2018-06-05545300ND
2018-06-05545301ND
2018-07-16560974ND
2018-08-28561294ND
2018-08-28561295ND
2018-08-28561296ND
2018-08-28561293ND
2019-04-29604248ND
2019-07-22621275ND