Fact Sheet: Notice of Ambient Water Quality Criteria Document for Tributyltin (TBT) - Final

January 2004

The EPA has released a final ambient water quality criteria document for tributyltin (TBT). We developed acute and chronic criteria recommendations for TBT designed to protect aquatic life in both fresh and saltwater. These criteria can form the basis for state and tribal water quality standards.

• Background
• What are the final tributyltin (TBT) criteria concentrations?
  • Freshwater
  • Saltwater
• Additional Information

Background

TBT is an organotin compound used primarily as a biocide in antifouling paints. It is extremely toxic to aquatic life and is an endocrine-disrupting chemical that causes severe reproductive effects in aquatic organisms. TBT is extremely stable and resistant to natural degradation in water. Because of its chemical properties and widespread use as an antifouling agent, concerns have been raised over the risks it poses to both freshwater and saltwater organisms. The final ambient water quality criteria document for TBT contains ambient water quality criteria designed to protect aquatic organisms and their uses. 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 TBT water quality criteria are published pursuant to Section 304(a) of the Clean Water Act (CWA).

What are the final tributyltin (TBT) 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 TBT does not exceed 0.46 µg/L more than once every three years on the average (acute criterion) and if the four-day average concentration of TBT does not exceed 0.072 µg/l more than once every three years on the average (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 TBT does not exceed 0.42 µg/L more than once every three years on the average (acute criterion) and if the four-day average concentration of TBT does not exceed 0.0074 µg/L more than once every three years on the average (chronic criterion).

Additional Information

Ambient Aquatic Life Water Quality Criteria for Tributyltin (TBT) - Final (pdf) (336.17 KB, December 2003, EPA 822-R-03-031)