Atrazine
Regional Water Authority
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.
Samples
Samples exceeding legal limit (MCL)
Samples exceeding
health guidelines
Testing results - average by year
| Year | Average result | Samples taken | Detections | Range of results |
|---|---|---|---|---|
| 2018 | N/A | 0 | 0 | N/A |
| 2019 | ND | 22 | 0 | ND |
| 2020 | N/A | 0 | 0 | N/A |
| 2021 | N/A | 0 | 0 | N/A |
| 2022 | ND | 32 | 0 | ND |
| 2023 | N/A | 0 | 0 | N/A |
ppb = parts per billion
State, National, and Health Guidelines for Drinking Water
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 |
|---|---|---|
| 2019-05-08 | SOC 200531300 | ND |
| 2019-05-28 | SOC 200533720 | ND |
| 2019-05-28 | SOC 200533719 | ND |
| 2019-05-28 | SOC 200533803 | ND |
| 2019-05-28 | SOC 200533804 | ND |
| 2019-05-28 | SOC 200533660 | ND |
| 2019-05-28 | SOC 200533659 | ND |
| 2019-05-29 | SOC 200533881 | ND |
| 2019-05-29 | SOC 200533880 | ND |
| 2019-05-29 | SOC 200533867 | ND |
| 2019-05-29 | SOC 200533868 | ND |
| 2019-08-26 | SOC 200546197 | ND |
| 2019-08-26 | SOC 200546198 | ND |
| 2019-08-26 | SOC 200546200 | ND |
| 2019-08-27 | SOC 200546267 | ND |
| 2019-08-27 | SOC 200546303 | ND |
| 2019-08-27 | SOC 200546302 | ND |
| 2019-08-27 | SOC 200546268 | ND |
| 2019-08-28 | SOC 200546738 | ND |
| 2019-08-28 | SOC 200546737 | ND |
| 2019-08-28 | SOC 200546736 | ND |
| 2019-08-28 | SOC 200546553 | ND |
| 2022-07-11 | S300210822 300210824 | ND |
| 2022-07-11 | S300210156 300210158 | ND |
| 2022-07-11 | S300210164 300210166 | ND |
| 2022-07-11 | S300210651 300210653 | ND |
| 2022-07-11 | S300210659 300210661 | ND |
| 2022-07-12 | S300211086 300211088 | ND |
| 2022-07-12 | S300211076 300211078 | ND |
| 2022-07-12 | S300211068 300211070 | ND |
| 2022-07-13 | S300212413 300212415 | ND |
| 2022-07-13 | S300212421 300212423 | ND |
| 2022-07-14 | S300212957 300212959 | ND |
| 2022-10-17 | S300258850 300258852 | ND |
| 2022-10-17 | 300258850 300258852B | ND |
| 2022-10-17 | 300258858 300258860B | ND |
| 2022-10-17 | S300258858 300258860 | ND |
| 2022-10-18 | S300259358 300259360 | ND |
| 2022-10-18 | S300258921 300258923 | ND |
| 2022-10-18 | 300258921 300258923B | ND |
| 2022-10-18 | 300259358 300259360B | ND |
| 2022-10-18 | S300259350 300259352 | ND |
| 2022-10-18 | 300259350 300259352B | ND |
| 2022-10-18 | 300258913 300258915B | ND |
| 2022-10-18 | S300258913 300258915 | ND |
| 2022-10-19 | S300259930 300259934 | ND |
| 2022-10-19 | 300259930 300259934B | ND |
| 2022-10-19 | 300259940 300259942B | ND |
| 2022-10-19 | S300259940 300259942 | ND |
| 2022-10-19 | S300260499 300260501 | ND |
| 2022-10-19 | 300260499 300260501B | ND |
| 2022-10-19 | 300260507 300260509B | ND |
| 2022-10-19 | S300260507 300260509 | ND |
| 2022-12-06 | S300281400 300281402 | ND |