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Through an epidemiological research project, ORAU Biostatistician Ashley Golden, Ph.D., and ORAU Epidemiologist Betsy Ellis, Ph.D., collaborated with Hien Le, Ph.D., lead epidemiologist of Chemours Co., to evaluate whether different statistical methods produce similar results. The study focused on the possible harmful effects of occupational exposure to titanium dioxide (TiO2), a white pigment widely used in consumer products, such as sunscreen, cosmetics, paint and plastics.

Exposure through inhalation during manufacturing led the International Association for Research on Cancer to classify TiO2 as “possibly carcinogenic to humans” based on sufficient experimental animal evidence. The researchers examined a cohort of 3,607 U.S. workers, followed 1935-2006, to investigate the relationship between TiO2 exposure and death from lung cancer, nonmalignant respiratory disease and heart disease using Cox Proportional Hazards modeling and Poisson regression. They concluded there was no statistically increased risk of death, and the two statistical models had equivalent results, but the Cox Proportional Hazards had greater precision.

These findings validate previously published studies in the scientific literature and provide support for precise and reliable statistical methodology in future studies.

Contact us

For more information or to request support with epidemiology or exposure science studies, contact Dr. Ashley Golden at 865.241.3744,, or Dr. Betsy Ellis at 865.576.3528,

For more information about contracting with ORAU, contact Dominic Moro at 865.241.1446 or