Draft Document on Titanium Dioxide Posted by NIOSH for Public Comment
November 23, 2005
Contact: Fred Blosser (202) 401-3749
The National Institute for Occupational Safety and Health (NIOSH) is requesting public comment on a draft Current Intelligence Bulletin, “Evaluation of Health Hazard and Recommendations for Occupational Exposure to Titanium Dioxide.”
The draft document is posted on NIOSH’s web page at https://www.cdc.gov/niosh/review/public/TIo2/default.html for public comment by March 31, 2006.
Titanium dioxide (TiO2), an insoluble white powder, is used extensively in many commercial products, including paint, cosmetics, plastics, paper, and food, as an anti-caking or whitening agent. It is produced and used in the workplace in varying particle-size fractions, including fine and ultrafine sizes.
“The draft document is based on NIOSH’s rigorous assessment of the most current available scientific information about this widely used material,” said NIOSH Director John Howard, M.D. “We encourage our partners and stakeholders to provide input and feedback before we proceed to a final document.”
Dr. Howard added, “We are also posting a link to the draft document from the NIOSH Web topic page on the occupational safety and health implications and applications of nanotechnology. We hope that the discussion of issues pertaining to ultrafine particles of titanium dioxide at the nanoscale size – that is, particles smaller than 0.1 micrometers in diameter – will also help advance our concurrent dialogue about the science relating to potential occupational health effects of nanomaterials.”
Among the draft findings and recommendations on which NIOSH is requesting comment are these:
The draft document recommends exposure limits of 1.5 milligrams per cubic meter for fine TiO2 (particles greater than 0.1 micrometers in diameter) and 0.1 mg/m3 for ultrafine particles as time-weighted averages for up to 10 hours per day during a 40-hour work week. Exposures should be reduced to levels as low as feasible below those recommended limits, the draft further states.
The draft document says that the differences in recommended limits for fine and ultrafine particles reflect findings from studies which suggest that ultrafine TiO2 particles may be more potent than fine TiO2 particles at the same mass. This may be due to the fact that the ultrafine particles have a greater surface area than the fine particles at the same mass, the draft states.
The draft document says that the recommended exposure limits would control occupational exposures to levels that are unlikely to raise a risk of work-related lung cancer, based on available evidence from laboratory animal studies. With this recommendation, NIOSH would remove its current classification of TiO2 as an occupational carcinogen, but would reconsider this determination if additional scientific evidence became available.
The draft document says that further research is critically needed in the measurement of workplace airborne exposures to ultrafine TiO2 in facilities that produce the material, in order to better understand potential exposure risks. Further research also is needed, it adds, on 1) the exposure-response relationships between ultrafine PSLT (poorly soluble, low toxicity) particles and human health effects, 2) the fate of ultrafine particles in the lung and associated responses in the pulmonary system, and 3) the effectiveness of engineering controls for controlling exposures to fine and ultrafine TiO2 particles.
NIOSH will hold a public meeting on the draft document on Feb. 27, 2006. Once further details about the meeting are completed, they will be published in a forthcoming Federal Register notice and will be posted with the draft document. In the meantime, questions about the public meeting may be directed to Christine Sofge, Ph.D., NIOSH, at (513) 533-8439. The draft document also will receive peer review; further details of that peer review also will be posted on the NIOSH Web page in the near future.