Table 1.

Doses of furan and group sizes for each dose administered to male F344/N Nctr rats for 2 years and the predicted incidence of cholangiocarcinoma at 2 years^a

Doses of furan (mg/kg BW)	Total number of rats/group	Number of rats examined at the 36-week interim sacrifice	Number of rats examined at the 60-week interim sacrifice	Number of rats remaining for the entire 2-year bioassay	Predicted cholangiocarcinoma incidence at 2 yearsb
0	190	20	20	150	0%
0.02	180	20	10	150	0 – 23%
0.044	130	20	10	100	0 – 37%
0.092	130	20	10	100	19 – 50%
0.2	80	20	10	50	41 – 64%
0.44	80	20	10	50	63 – 78%
0.92	80	20	10	50	83 – 92%
2	80	20	10	50	100%

^aFuran was administered by gavage in corn oil vehicle 5 days/week for 2 years (104 weeks), with interim sacrifices conducted at 36 and 60 weeks.

^bThe predicted cholangiocarcinoma incidences were derived with the empirical relationship of Peto et al. (1984), using exponents of 2 and 3.