United States Off ice of Water EPA-822-F-05-001
Environmental Protection Agency 4304T February 2006
Fact Sheet: Final Recommended Aquatic Life
Ambient Water Quality Criteria for Diazinon
The final recommended aquatic life ambient water quality criteria document for diazinon contains
acute and chronic criteria recommendations designed to protect aquatic life in both freshwater and
saltwater. While these criteria recommendations do not, in themselves, impose any requirements,
states and authorized tribes can use them to develop water quality standards.
What is diazinon?
Diazinon is a pesticide traditionally used throughout the U.S. to control insects in agricultural areas,
households and urban settings. After December 31, 2004, it became unlawful to sell diazinon for
outdoor, non-agricultural uses in the United States (that is, all residential uses of the insecticide
diazinon have been cancelled). However, it is lawful to use diazinon for non-residential or
agricultural uses that are consistent with product labeling and precautions approved by EPA under
the Federal Insecticide, Fungicide and Rodenticide Act.
Diazinon is mobile and moderately persistent in the environment. Diazinon is frequently found in
wastewater treatment plant effluent and storm water runoff in urban and agricultural areas. Diazinon
is known to be toxic to aquatic life, particularly invertebrates.
Why is EPA publishing the final criteria?
On December 31, 2003, the Agency published a Federal Register notice soliciting scientific views
on draft aquatic life criteria for diazinon (68 FR 75555). Based on the information we received,
EPA revised the draft criteria and is now publishing the final recommended aquatic life ambient
water quality criteria for diazinon.
What are the final diazinon ambient water quality criteria concentrations?
Freshwater Aquatic Life:
Freshwater aquatic life should not be affected if the one-hour average concentration of diazinon
does not exceed 0.17 micrograms per liter more than once every three years on the average (acute
criterion) and if the four-day average concentration of diazinon does not exceed 0.17 micrograms
per liter more than once every three years on the average (chronic criterion).
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Saltwater Aquatic Life:
Saltwater aquatic life should not be affected if the one-hour average concentration of diazinon does
not exceed 0.82 micrograms per liter more than once every three years on the average (acute
criterion) and if the four-day average concentration of diazinon does not exceed 0.82 micrograms
per liter more than once every three years on the average (chronic criterion).
How do I get a copy of the final diazinon document?
You can get copies of "Aquatic Life Ambient Water Quality Criteria for Diazinon - Final" (EPA-
822-F-05-006) 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/diazinon/index.htm.
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