The effects of Thorotrast and quartz on the induction of lung tumors in rats.

In a long-term animal study, the combined and separate effects of Thorotrast (colloidal 232 ThO 2 ) and silica dust on the induction of lung tumors were investigated. Female Wistar rats were exposed for 29 d to aerosol concentrations of quartz of either 6 mg m -3 , 30 mg m -3 , or 0 mg m -3 (6 h d -1 , 5 d wk -1 ). After inhalation, one-half of all exposed animals received a single intravenous injection of enriched Thorotrast (600 μL, 2960 Bq 228 Th mL -1 )