This is a fact sheet about a chemical that may be found in some public or
private drinking water supplies. It may cause health problems if found
in amounts greater than the health standard set by the United States
Environmental Protection Agency (EPA).
What is Simazine and how is it used?
Simazine is an organic white solid, used as a pre-emergence herbicide used
for control of broad-leaved and grassy weeds on a variety of deep-rooted
crops such as artichokes, asparagus, berry crops, broad beans, citrus,
etc., and on non-crop areas such as farm ponds and fish hatcheries. Its
major use is on corn where it is often combined with AAtrex. Other
herbicides with which simazine is combined include: paraquat, on apples,
peaches; Roundup or Oust for noncrop use; Surflan on Christmas trees;
Dual on corn and ornamentals.
The list of trade names given below may help you find out whether you
are using this chemical at home or work.
Trade Names and Synonyms:
Why is Simazine being regulated?
In 1974, Congress passed the Safe Drinking Water Act. This law requires
EPA to determine safe levels of chemicals in drinking water which do or
may cause health problems. These non-enforceable levels, based solely on
possible health risks and exposure, are called Maximum Contaminant Level
The MCLG for simazine has been set at 4 parts per billion (ppb)
because EPA believes this level of protection would not cause any of the
potential health problems described below.
Based on this MCLG, EPA has set an enforceable standard called a
Maximum Contaminant Level (MCL). MCLs are set as close to the MCLGs as
possible, considering the ability of public water systems to detect and
remove contaminants using suitable treatment technologies.
The MCL has also been set at 4 ppb because EPA believes, given
present technology and resources, this is the lowest level to which
water systems can reasonably be required to remove this contaminant
should it occur in drinking water.
These drinking water standards and the regulations for ensuring
these standards are met, are called National Primary Drinking Water
Regulations. All public water supplies must abide by these regulations.
What are the health effects?
Short-term: EPA has found simazine to potentially cause the following
health effects when people are exposed to it at levels above the MCL for
relatively short periods of time: weight loss, changes in blood.
Long-term: Simazine has the potential to cause the following
effects from a lifetime exposure at levels above the MCL: tremors;
damage to testes, kidneys, liver and thyroid; gene mutations; cancer.
How much Simazine is produced and released to the environment?
The amount of simazine used annually in the USA was estimated in 1985 to
be 4.8 billion pounds. Simazine may be released into the environment via
effluent at manufacturing sites and at points of application where it is
employed as a herbicide.
What happens to Simazine when it is released to the environment?
If released to water, simazine will not bind to sediments or evaporate. It
may leach to ground water. Its persistence varies from a few months to a
few years, depending mainly on the rate of degradation by microbes.
Simazine has a low potential to bioaccumulate in fish.
How will Simazine be detected in and removed from my drinking water?
The regulation for simazine became effective in 1994. Between 1993 and
1995, EPA required your water supplier to collect water samples every 3
months for one year and analyze them to find out if simazine is present
above 0.07 ppb. If it is present above this level, the system must
continue to monitor this contaminant.
If contaminant levels are found to be consistently above the MCL,
your water supplier must take steps to reduce the amount of simazine so
that it is consistently below that level. The following treatment
methods have been approved by EPA for removing simazine: Granular
How will I know if Simazine is in my drinking water?
If the levels of simazine exceed the MCL, 4 ppb, the system must notify
the public via newspapers, radio, TV and other means. Additional
actions, such as providing alternative drinking water supplies, may be
required to prevent serious risks to public health.
This is a factsheet about a chemical that may be found in some
public or private drinking water supplies. It may cause health problems
if found in amounts greater than the health standard set by the United
States Environmental Protection Agency (EPA).
Drinking Water Standards:
|Mclg: 4 ppb (parts per billion)
Note: This fact sheet is part of a larger
publication adapted from U.S. EPA publication: EPA National Primary
Drinking Water Regulations.