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 Picloram and how is it used?
Picloram is a crystalline organic solid with a chlorine-like odor. It is
used in salt form as a systemic herbicide for controlling annual weeds
on crops, and in combination with 2,4-D or 2,4,5-T against perennials on
non-croplands for brush control. Picloram is used to control bitterweed,
knapweed, leafy spurge, locoweed, larkspur, mesquite, prickly pear, and
snakeweed on rangeland in the western states.
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 Picloram 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 picloram has been set at 0.5 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 also been set at 0.5 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 picloram to potentially cause the following
health effects when people are exposed to it at levels above the MCL for
relatively short periods of time: damage to central nervous system,
weakness, diarrhea, weight loss.
Long-term: Picloram has the potential to cause the following
effects from a lifetime exposure at levels above the MCL: liver damage.
How much Picloram is produced and released to the environment?
EPA estimates that 300,000 lbs. of picloram were produced in the US in
Picloram is released to the environment primarily from its
application as a herbicide, and also during its production and handling.
What happens to Picloram when it is released to the environment?
Picloram is the most persistent of its family of herbicides. It does not
adhere to soil and so may leach to groundwater, and has in fact been
detected there. It is degraded in soil and water mainly by microbes.
Picloram has very little tendency to accumulate in aquatic life.
How will Picloram be detected in and removed from my drinking water?
The regulation for picloram became effective in 1994. Between 1993 nd
1995, EPA required your water supplier to collect water samples every 3
months for one year and analyze them to find out if picloram is present
above 0.1 part 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 picloram so
that it is consistently below that level. The following treatment
methods have been approved by EPA for removing picloram: Granular
How will I know if Picloram is in my drinking water?
If the levels of picloram exceed the MCL, 0.5 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: 0.5 ppm (parts per million)
Mcl: 0.5 ppm