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 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:
Miller Nu Set
Why is Silvex
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 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
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
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
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.
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: 0.05 ppm (parts per million)