Atrazine
Notice of Revised Draft Ambient Water Quality Criteria Document
for Atrazine and Request for Scientific Views
Fact Sheet: EPA-822-F-03-006; November 2003
Summary
EPA has released and requested scientific views on a revised draft
ambient water quality criteria document for atrazine. We developed
acute and chronic criteria recommendations for atrazine designed
to protect aquatic life in both freshwater and saltwater. At the
same time, EPA released its revised Ecological Fate and Effects
Risk Assessment for atrazine. Both documents incorporate our responses
to additional information that became available after we published
the earlier draft criteria atrazine water quality criteria document.
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Background
Atrazine is an herbicide used throughout the U.S. to control weeds
in agricultural crops. It is moderately volatile, soluble in water,
and resistant to natural degradation in water. Because of its chemical
properties and widespread use as an herbicide, concerns have been
raised over the risks it poses for both freshwater and saltwater
organisms.
On September 26, 2001, the Agency published a draft criteria document
and requested scientific views and information. EPA then extended
the period for scientific information to close on Janaury 25, 2002,
to allow all interested parties the opportunity to submit scientific
views. The revised draft criteria document reflects the results
of our consideration of the additional information that became available
on scientific issues related to deriving the atrazine criteria and
on the risk assessment methods we used.
The revised draft ambient water quality criteria document for atrazine
contains ambient water quality criteria designed to protect aquatic
organisms and their uses. Once final, these criteria are guidance
for states and tribes and, in themselves, have no binding legal
effect. However, they may form the basis for state water quality
standards and become enforceable through NPDES permits or other
environmental programs. These new draft atrazine criteria are published
pursuant to Section 304(a) of the Clean Water Act (CWA).
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What are the revised draft atrazine criteria
concentrations?
Freshwater Aquatic Life:
Except possibly where a locally important species is very sensitive,
freshwater aquatic life and their uses should not be affected unacceptably
if the one-hour average concentration of atrazine does not exceed
1,500 ug/L more than once every three years on the average (acute
criterion) and if the Average Primary Producer Steinhaus Similarity
deviation for a site is less than 5% (as determined using Comprehensive
Aquatic Systems Model (CASM) or other appropriate model and index)
and is not exceeded more than once every three years (or other appropriate
return frequency sufficient to allow system recovery). The 5% index
for the protection of aquatic plant community should also be protective
of most freshwater animals (chronic criterion).
Saltwater Aquatic Life:
Except possibly where a locally important species is very sensitive,
saltwater aquatic life and their uses should not be affected unacceptably
if the one-hour average concentration of atrazine does not exceed
760 ug/L more than once every three years on the average (acute
criterion) and if the thirty-day average concentration of atrazine
does not exceed 17 ug/L more than once every three years on the
average (chronic criterion).
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How are the revised criteria in today's publication
different from the 2001 criteria?
The revised criteria in today's publication incorporate information
on the toxicity of atrazine to aquatic plants and invertebrates
that had not been available at the time of the 2001 publication.
The change in critical endpoints reflects the scientific views received
from the public.
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How do I get a copy of the new draft atrazine
document?
You can get copies of "Ambient Aquatic Life Water Quality
Criteria for Atrazine - Revised Draft" (EPA-822-R-03-023) from
EPA's Water Resource
Center by calling (202) 566-1729. You can request a copy by
sending an e-mail to center.water.resource@epa.gov or by conventional
mail to: EPA Water Resource Center, 4101T, 1200 Pennsylvania Avenue,
N.W., Washington, DC 20460. You can also download the document from
EPA's web site at: http://www.epa.gov/waterscience/criteria/atrazine/atrazref.html.
The
Office of Pesticide Program's Ecological Fate and Effects Risk Assessment
for atrazine
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