Treatment groups and abbreviations used in the 90 day exposure to the 26 chemicals and corresponding vehicle controls used in this study.

aI  =  inhalation; F  =  feed; GC  =  gavage, corn oil (5 ml/kg); GW  =  gavage, deionized water (5 ml/kg).
bThe results for liver tumors were based on a p = 0.01 threshold for combined increase in adenomas or carcinomas.
cThe results for liver tumors in this study were considered equivocal or borderline significant. Combined increase in hepatocellular adenomas or carcinomas resulted in p = 0.075 and p = 0.084 for benzene and coumarin respectively.
dDue to signs of toxicity, the 16,000 ppm dose was reduced to 0 ppm on day 9 for a period of 2 days. The dose was raised to 8,000 ppm for a period of 9 days and returned to 16,000 ppm for the remainder of the study. The time weighted average dose was 14,800 ppm.
eThe initial dose of 3,000 ppm was reduced to 2,000 ppm in week 2 of the study due to taste aversion and weight loss. The 2,000 ppm dose is the same as the low dose in the original bioassay.
fChemical not evaluated by the NTP. Bioassay performed by Alexander etal.[20].