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 Dinoseb and how is it used?
Dinoseb is an organic solid - yellowish crystals with a pungent odor. Its
greatest use is as a contact herbicide for post-emergence weed control
in cereals, undersown cereals, seedling lucerne and peas. Dinoseb is
also used as a corn yield enhancer and an insecticide and miticide.
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:
Dow Selective Weed Killer
Why is Dinoseb 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 dinoseb has been set at 7 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 been set at 7 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 dinoseb to potentially cause the following
health effects when people are exposed to it at levels above the MCL for
relatively short periods of time: sweating, headache, mood changes.
Long-term: Dinoseb has the potential to cause the following effects from
a lifetime exposure at levels above the MCL: decreased body and thyroid
weight, degeneration of testes; thickening of intestinal lining.
How much Dinoseb is produced and released to the environment?
1982 production of dinoseb was reported as 6.2 million pounds, used
primarily on soybeans and vegetables. Release of dinoseb has resulted
primarily from its use as an herbicide on a variety of weeds.
What happens to Dinoseb when it is released to the environment?
Dinoseb is degraded slowly by soil bacteria and binds weakly to soil.
Therefore, leaching in soil is possible and dinoseb has been detected in
groundwater. In water, dinoseb is mainly broken down by sunlight. It is
not likely to accumulate in aquatic life.
How will Dinoseb be detected in and removed from my drinking
The regulation for dinoseb 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 dinoseb is present
above 0.2 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 dinoseb so
that it is consistently below that level. The following treatment
methods have been approved by EPA for removing dinoseb: Granular
How will I know if Dinoseb is in my drinking water?
If the levels of dinoseb exceed the MCL, 7 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:
Note: This fact sheet is part of a larger publication
adapted from U.S. EPA publication: EPA National Primary Drinking Water
|Mclg: 7 ppb (parts per billion)
Mcl: 7 ppb