Identification of research needs to resolve the carcinogenicity of high-priority IARC Carcinogens. Views and expert opinions of an IARC/NORA expert group meeting, Lyon, France, 30 June - 2 July 2009. Lyon, France: International Agency for Research on Cancer, IARC Technical Publication No. 42. 2010 Jul; 42:30-39
Experimental studies are needed to elucidate the biological mechanisms between particle-induced inflammation and lung cancer. A study examining the relationship between TiO2 exposure in workers and validated markers of oxidative stress, with quantitative comparison in rodent studies, could provide data on interpretation of the animal studies for predicting lung cancer risk in humans. Studies are needed that provide mechanistic linkages between the biological responses observed in short-term or subchronic studies and the adverse health effects observed with chronic exposure. The same species, strain, and gender should be used. For example, different mouse strains were used in Heinrich et al. (1995) and in Bermudez et al. (2004), making it difficult to determine whether the subchronic inflammation results are relevant to the chronic lung responses observed in another mouse strain. The observation of inhaled discrete nanoscale TiO2 particles inside rat alveolar epithelial cell organelles including the nucleus (Geiser et al., 2005) suggests that possible direct genotoxic mechanisms for lung cancer should be examined. Given the increasing applications of nano-TiO2 in consumer products (e.g., food or food packaging and skin care products), there is a need to develop better techniques to detect TiO2 in tissues and to examine possible carcinogenicity of nano-TiO2 by other routes of exposure (oral, dermal). A chronic feeding study of nanoscale TiO2 may be appropriate.
Cancer; Carcinogens; Carcinogenesis; Carcinogenicity; Lung; Lung-cancer; Lung-cells; Lung-disease; Lung-disorders; Lung-function; Lung-tissue; Oxidative-processes; Animals; Animal-studies; Biological-effects; Chronic-exposure; Respiratory-system-disorders; Pulmonary-system-disorders; Nanotechnology
Identification of research needs to resolve the carcinogenicity of high-priority IARC Carcinogens. Views and expert opinions of an IARC/NORA expert group meeting, Lyon, France, 30 June - 2 July 2009