EWG's Tap Water Database — 2019 UPDATE



Henry County Regional Water & Sewer District - Co. Rd. P

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 exceeding legal limit (MCL)


Samples exceeding
health guidelines

Testing results - average by year

YearAverage resultSamples takenDetectionsRange of results
20120.140 ppb96ND - 0.489 ppb
20130.128 ppb97ND - 0.580 ppb
20140.170 ppb92ND - 1.41 ppb
20150.0256 ppb91ND - 0.230 ppb
20160.0492 ppb106ND - 0.140 ppb
20170.0400 ppb93ND - 0.140 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