Cumulative Toxicity Potential of Hardwood Dust and Sidestream Tobacco Smoke in Rats by Repeated Inhalation

Abstract

There are few inhalation studies of hardwood carcinogenesis. In this study, Wistar male rats (4 wk old) were exposed to hardwood dust generated directly by a belt sander (mass median aerodynamic diameter 7.2 µm) for 6 h/day, 5 dayslwk for 6 mo. The average exposure concentration was controlled at 15.3 mg/m³ during the exposure. Some rats were exposed to sidestream of tobacco smoke of 10 cigarettes per day, 5 dayslwk for 1 mo following the exposure to wood dust for 6 mo.

For histopathological examination, the rats were sacrificed at 18 mo after the start of the experiment. There was no nasal cancer in any of the exposed rats, although the rats were exposed continuously to hardwood dust for 6 mo and tobacco smoke for 1 mo and kept for an 11-mo clearance period.