Titanium dioxide hazard communication in material safety data sheets

November 19, 1997

Mr. Douglas C. Markley
North American Refractories Co.
[Recipient address omitted]
Dear Mr. Markley:

This is in response to your letter of October 15, requesting information about the carcinogen status of titanium dioxide
(TiO₂) relative to Occupational Safety and Health Administration (OSHA) standards.

From a regulatory standpoint OSHA does not regulate TiO₂ as a carcinogen. The permissible exposure limit for TiO₂ is 15mg/m³, as total dust, expressed as an 8-hour time-weighted average.

However, under the Hazard Communication standard, 29 CFR 1910.1200, the material safety data sheet must convey the fact that TiO₂ is a potential carcinogen to rats for hazard communication purposes. This is presumably based on NIOSH's interpretation of the study by Lee, Trochimowicz, and Reinhardt [1985], "Pulmonary Response of Rats Exposed to Titanium Dioxide (TiO₂) by Inhalation for Two Years." The authors of this study concluded that based on the excessive dust loading and overwhelmed clearance mechanism in the lungs of rats exposed chronically at 250 mg/m³ (6 hrs/day, 5 days/week for 2 years), the biological relevance of lung tumors to man appears to be negligible. A copy of the study is enclosed.

It should also be noted that the chemical manufacturer, importer, or employer may also report the results of other scientifically valid studies which tend to refute the findings of a hazard.

We trust that this letter addresses your concerns about reporting information on the MSDS. Should you have any further questions or need additional assistance please contact Ira Wainless of my staff at (202) 219-7056.

Thank you for your interest in occupational health.

Sincerely,

Steven F. Witt
Director
Directorate of Technical Support

Enclosure

[Requester letter reproduced on OSHA page; omitted here.]