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 Endothall and how is it used?
Endothall is an organic solid of white odorless crystals. Endothall is
used as a defoliant for a wide range of crops and as a herbicide for
both terrestrial and aquatic weeds. It is used as a desiccant on lucerne
and on potato, for the defoliation of cotton, to control aquatic weeds
and as an aquatic algicide growth regulator. It has been used for: sugar
beets, turf, hops sucker suppression; alfalfa, clover desiccants; potato
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:
Endothall Turf Herbicide
Endothall Weed Killer
Why is Endothall 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 endothall has been set at 0.1 parts per million (ppm)
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 been set at 0.1 ppm 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 endothall to potentially cause the following
health effects when people are exposed to it at levels above the MCL for
relatively short periods of time: depressed breathing and heart rate.
Long-term: Endothall has the potential to cause the following
effects from a lifetime exposure at levels above the MCL: increase in
size of some internal organs, particularly the stomach and intestine.
How much Endothall is produced and released to the environment?
EPA estimated total domestic usage in 1982 to have been approximately 1.5
million lbs. Release of endothall to the environment is expected to
occur primarily during its use as a pre-emergence, post-emergence, turf
and aquatic herbicide and harvest aid. Other sources of release include
loss during manufacturing, formulation, packaging or disposal of this
What happens to Endothall when it is released to the environment?
Endothall is expected to be quickly broken down by microbes in soil or
water. It is also able to leach through soil into ground water; however,
rapid degradation would limit the extent of leaching.
Endothall is not likely to accumulate in aquatic life.
How will Endothall be detected in and removed from my drinking
The regulation for endothall 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 endothall is present
above 9 parts per billion. 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 endothall so
that it is consistently below that level. The following treatment
methods have been approved by EPA for removing endothall: Granular
How will I know if Endothall is in my drinking water?
If the levels of endothall exceed the MCL, 0.1 ppm, 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:
Note: This fact sheet is part of a larger publication
adapted from U.S. EPA publication: EPA National Primary Drinking Water
|Mclg: 0.1 ppm (parts per million)
Mcl: 0.1 ppm