Table I.

Lung and pancreatic lesions in male F-344 rats given (S)-NNAL, (R)-NNAL, NNK or racemic NNAL in their drinking water

		Control		(R)-NNAL, 5 ppm		(S)-NNAL, 5 ppm	NNK, 5 ppm	Racemic NNAL, 10 ppm
A. Tumor incidence
No. of rats necropsied		22		24		22	24	15
No. of rats with histologically confirmed lung lesions
Hyperplasia		0		24		22	24	15
Adenoma		0		23		22	24	15
Carcinoma		0		6a		10a	17a,b	15a
Tumor incidence		0		23c		22c	24c	15c
No. of rats with thoracic cavity tumors		0		2		2	6	9
No. of rats with metastasis to pancreas		0		1d		2e	3f	4g,h
	Gross lung lesion score						Number of rats with lesions	Number of rats evaluated
	0	1	2	3	4
B. Gross lung lesion scores
Control	21	0	0	0	0		0	21i
(R)-NNALj	0	6	16	1	0		23	23
(S)-NNAL	0	2	17	3	0		22	22
NNKj	0	0	9	11	3k		23	23
Racemic NNAL	0	0	4	8	3		15	15

^a P < 0.01 compared with control.

^bGreater than (R)-NNAL, P = 0.0015.

^c P < 0.0001 compared with control.

^dOne rat with two tumors.

^eOne rat with one tumor and one rat with two tumors.

^fEach rat had one tumor.

^gOne rat with one tumor; one with three tumors, one with four tumors and one with six tumors. A total of 14 pancreatic tumors were observed in this group.

^h P < 0.05 versus control.

ⁱThe control group had 22 animals, of which one was excluded because of lung lesions attributable to large granular lymphocyte leukemia.

^jOne animal in the (R)-NNAL and NNK groups was not scored due to prior sectioning of lungs for histology.

^kOverall gross lung lesion score significantly greater than (R)-NNAL (P < 0.0001) and (S)-NNAL (P = 0.0006).