Simazine
Harris County Water Control and Improvement District 110
Simazine is a hormone-disrupting herbicide related to atrazine. It affects the male and female reproductive systems. In studies of laboratory animals, simazine increases blood levels of estrogen, decreases prolactin and progesterone, and causes mammary and ovarian tumors.
Samples
Samples exceeding legal limit (MCL)
Samples exceeding
health guidelines
Testing results - average by year
| Year | Average result | Samples taken | Detections | Range of results |
|---|---|---|---|---|
| 2014 | ND | 1 | 0 | ND |
| 2015 | ND | 2 | 0 | ND |
| 2016 | ND | 1 | 0 | ND |
| 2017 | ND | 1 | 0 | ND |
| 2018 | ND | 2 | 0 | ND |
| 2019 | 0.150 ppb | 1 | 1 | 0.150 ppb |
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 simazine 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) 4 ppb
The legal limit for simazine, established in 1992, was based on toxicity studies 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 |
|---|---|---|
| 2014-08-21 | AC64959 | ND |
| 2015-08-06 | AD03078 | ND |
| 2015-08-06 | AD03076 | ND |
| 2016-11-16 | AD58397 | ND |
| 2017-09-20 | AD97252 | ND |
| 2018-06-19 | AE30853 | ND |
| 2018-06-19 | AE30855 | ND |
| 2019-12-02 | AE90864 | 0.150 ppb |