OSHA requirements are set by statute, standards and regulations. Our interpretation letters explain these requirements and how they apply to particular circumstances, but they cannot create additional employer obligations. This letter constitutes OSHA's interpretation of the requirements discussed. Note that our enforcement guidance may be affected by changes to OSHA rules. Also, from time to time we update our guidance in response to new information. To keep apprised of such developments, you can consult OSHA's website at https://www.osha.gov.

November 19, 1997

Mr. Douglas C. Markley
North American Refractories Co.
500 Halle Building
1228 Euclid Avenue
Cleveland, Ohio 44115-1809

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.


Steven F. Witt
Directorate of Technical Support




500 Halle Building
1228 Euclid Avenue
Cleveland, Ohio 44115-1809
(216) 621-5200

North American Refractories Co.

October 15, 1997

Occupational Safety and Health Adminstraiion
Office of Technical Support
200 Constitution Ave. NW
Washington, D.C. 20211

To whom it may concern:

My question relates to the listing of OSHA carcinogens and the Hazard Communication Standard.

My company has received an MSDS from a supplier that lists Titaniun Dioxide as a carcinogen. TiO2 is an impurity in their clay mineral produce. They reference the NIOSH Pocketguide.

TiO2 is not listed as a carcinogen by either NTP or IARC.

The TLV and PEL show it to be nuisance dust.

Question: What is the carcinogen status of TiO2 as per OSHA?

If it is a carcinogen, under what exposure scenerio inhalation, dermal contact etc.?

If it is a carcinogen, why does it have the nuisance dust PEL & TLV?

Is TiO2 required to be reported as a carcinogen on MSDS's according to the Haz Com Standrard?


Douglas C. Markley
Product Safety Coordinator