Inhalation studies with polyurethane foam dust in relation to respiratory tract carcinogenesis

Male and female Sprague-Dawley rats were exposed to freshly generated polyurethane foam dusts, in concentrations averaging 8.65 mg/m3 air, for 6 hours daily 5 days a week over a period of 12 weeks. For comparison the same numbers of rats were exposed to titanium dioxide (TiO2) (15.95 mg/m3 air), which is a known inert dust, and to air alone, as controls for the same exposure period. This exposure caused no noticeable changes in appearance, behavior, or body weight. The average lifespan values were within the normal range. A high tumor rate was seen in all groups, with no significant differences among the groups. No indications of a carcinogenic effect of the inhaled dusts on the respiratory tract could be established. The numerous tumors found in the different organs and groups were of a spontaneous nature. The observed lung-reactions are discussed.