Nano-sized Titanium Dioxide Cited as Possible Carcinogen



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NIOSH Issues CIB 63, Occupational Exposure to Titanium Dioxide

     In April 2011, NIOSH (National Institute for Occupational Safety and Health), the federal agency responsible for recommending occupational safety and health standards and prescribing safe workplace exposure levels, issued Current Intelligence Bulletin (CIB) 63 (CIBs describe new scientific information concerning occupational hazards) titled Occupational Exposure to Titanium Dioxide.  In this CIB, NIOSH concludes that ultrafine (nano-sized) titanium dioxide is a potential occupational carcinogen. 

     ?Ultrafine? means titanium dioxide particles less than 100 nanometers in diameter.  The general term "nanoparticles," or particles referred to as "nano-sized," are those that measure between 1 and 100 nanometers.  Research to date suggests that nanoparticles, particularly when inhaled, can adversely impact the human body and in particular, the lungs.  For perspective, there are 1 billion nanometers in a meter. 

     Nanoparticles often exhibit different properties and behaviors than larger particles of the same substance.  This differentiation appears to be true for nanoparticles of titanium dioxide, according to NIOSH. 

     NIOSH recommended exposure limits of 0.3 mg/m3 of ultrafine titanium dioxide for up to ten hours/day during a 40 hour work week.  NIOSH concluded that insufficient data exists to classify fine (defined as all particle sizes collected by respirable particle sampling) titanium dioxide as a potential occupational carcinogen, although it did recommend exposure limits of fine titanium dioxide of 2.4 mg/m3 for up to 10 hours per day for a 40 hour work week.  Particle size was the only differentiating factor.

     Titanium dioxide is commonly used in the manufacture of paints and coatings, plastics, paper, inks, pharmaceuticals and cosmetics.  Titanium dioxide powder is a powerful and potent brightening pigment because of its high refractive index and resistance to discoloration upon exposure to ultraviolet light. 

     Some key points from this CIB are: 

  • Titanium dioxide is not directly carcinogenic, but it acts through a secondary genotoxicity mechanism that is primarily related to particle size and surface area. 
  • NIOSH?s conclusions apply only to inhaled titanium dioxide. 
  • Nano-sized titanium dioxide particles have a higher surface area than fine titanium oxide, and surface area is the critical metric for the different recommendations concerning occupational exposure levels.

     You can access the entire CIB, as well as related comments, via this link:

     Steptoe & Johnson PLLC has extensive experience counseling employers on occupational safety issues and defending toxic torts.  Should you have questions about this CIB or any related issue, please contact Karen. 








About the Author









Karen E. Kahle


Karen Kahle?s practice is devoted to litigation, with a focus on products liability, energy, class actions, and mass torts. She heads the firm?s Class Action & Mass Tort Team. Prior to practicing law, Ms. Kahle was a registered pharmacist and practiced pharmacy full-time from 1982 to 1987.

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