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Consumer Factsheet on: 2,4,5-TP (SILVEX)
List of Contaminants
As part of the Drinking Water and Health pages, this fact sheet is part of a larger publication: National Primary Drinking Water Regulations
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).
What is Silvex and how is it used?
2,4,5-TP is a white organic powder with little odor. Its use has been banned since 1985. The
greatest use of 2,4,5-TP was as a postemergence herbicide for control of woody plants, and
broadleaf herbaceous weeds in rice and bluegrass turf, in sugarcane, in rangeland improvement
programs, on lawns. Aquatic uses included control of weeds in ditches and riverbanks, on
floodways, along canals, reservoirs, streams, and along southern waterways.
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:
Weed-B-Gon
Propon
Silvi-Rhap
Sta-fast
Miller Nu Set
Aqua-Vex
Color-Set
Ded-Weed
Fenoprop
Fenormone
Fruitone T
Garlon
Kuran
Kurosal G/SL
Silvex
Why is Silvex 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 Goals.
The MCLG for 2,4,5-TP has been set at 0.05 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 0.05 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 2,4,5-TP to potentially cause the following health effects when people
are exposed to it at levels above the MCL for relatively short periods of time: depression and
other nervous system effects, weakness, stomach irritation and minor damage to liver and kidneys.
Long-term: 2,4,5-TP has the potential to cause the following effects from a lifetime exposure at
levels above the MCL: minor liver and kidney damage.
How much Silvex is produced and released to the environment?
In 1982, 2,4,5-TP production was 500,000 pounds. Former releases were from spraying on
rangelands, runoff from fields, and direct release to water for control of aquatic weeds.
What happens to Silvex when it is released to the environment?
2,4,5-TP will strongly bind to soils and is degraded by microbes, so it isn't likely to leach to
ground water. If released to water, 2,4,5-TP will bind to sediment, where microbes will slowly
degradeit. It has a very low potential for accumulating in aquatic life.
How will Silvex be Detected in and Removed from My Drinking Water?
The regulation for 2,4,5-TP became effective in 1992. 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 2,4,5-TP is present above 0.2 ppb. If it is present above this evel, 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 2,4,5-TP so that it is consistently below that level. The following
treatment methods have been approved by EPA for removing 2,4,5-TP: Granular activated
charcoal.
How will I know if Silvex is in my drinking water?
If the levels of 2,4,5-TP exceed the MCL, 0.05 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.
Drinking Water Standards:
Mclg: 0.05 ppmMcl: 0.05 ppm
Learn more about your drinking water!
EPA strongly encourages people to learn more about their drinking water, and to support local
efforts to protect and upgrade the supply of safe drinking water. Your water bill or telephone
book's government listings are a good starting point.
Your local water supplier can give you a list of the chemicals they test for in your water, as well
as how your water is treated.
Your state Department of Health/Environment is also a valuable source of information.
For help in locating these agencies or for information on drinking water in general, call: EPA's
Safe Drinking Water Hotline: (800) 426-4791.
For additional information on the uses and releases of chemicals in your state, contact the:
Community Right-to-Know Hotline: (800) 424-9346.
List of Contaminants
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