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Tributyltin oxide (TBTO) Quickview (CASRN 56-35-9)

Health assessment information on a chemical substance is included in IRIS only after a comprehensive review of toxicity data by U.S. EPA health scientists from several Program Offices, Regional Offices, and the Office of Research and Development.

Disclaimer: This QuickView represents a snapshot of key information. We suggest that you read the IRIS Summary to put this information into complete context.

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Status of Data for Tributyltin oxide (TBTO)

File First On-Line: 08/22/1988; Last Significant Revision: 09/01/1997

Category (section)
Last Revised
Oral RfD Assessment Yes 09/01/1997
Inhalation RfC Assessment Discussion 09/01/1997
Carcinogenicity Assessment Yes 09/01/1997
  • 56-35-9
  • Biomet tbto
  • Bis-(tri-n-butylcin)oxid
  • Bis(tributyloxide) of tin
  • Bis(tributylstannium) oxide
  • Bis(tributylstannyl)oxide
  • Bis(tributyltin)oxide
  • Bis(tri-n-butylzinn)-oxyd
  • BTO
  • Butinox
  • C-SN-9
  • more...
Tributyltin oxide (TBTO) Source Documents
Chronic Health Hazard Assessments for Noncarcinogenic Effects

Reference Dose for Chronic Oral Exposure (RfD)

Critical Effect
Point of Departure*
Immunosuppression BMD10 : 3 x10-2 mg/kg-day 100 3 x10-4 mg/kg-day

* The Point of Departure listed serves as a basis from which the Oral RfD was derived. See Discussion of Conversion Factors and Assumptions for more details.

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Reference Concentration for Chronic Inhalation Exposure (RfC)

Information reviewed but value not estimated. See IRIS Summary.

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Carcinogenicity Assessment for Lifetime Exposure
  • Weight-of-Evidence Characterization
    • D (Not classifiable as to human carcinogenicity)
    • Carcinogenic potential cannot be determined
  • Weight-of-Evidence Narrative:
    • There are no data in humans concerning development of cancer following exposure to tributyltin oxide (TBTO). Cancer bioassays following oral exposure have been conducted in rats and mice. Because of the questionable data from the bioassay in rats, EPA assigns TBTO to the "cannot be determined" category [U.S. EPA, 1996 (proposed)].
    • This may be a synopsis of the full weight-of-evidence narrative. See IRIS Summary.

Quantitative Estimate of Carcinogenic Risk from Oral Exposure

  • Not Assessed under the IRIS Program.

Quantitative Estimate of Carcinogenic Risk from Inhalation Exposure

  • Not Assessed under the IRIS Program.

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