Table 1.

Effect of carcinogens on intrachromosomal recombination

Strain of mice	Chemical	Dose	No. of mice treated	No. of live offsprings	Average litter size	No. of spotted offsprings	Frequency, %	Significance, P
pun/pun	Control	0	89	498	5.2	28	5.6
	X-rays	100 cGy	64	172	2.7	40	23	<10−6
	Control	0	101	585	5.8	62	11
	EMS	100 mg/kg	21	94	4.5	27	29	≪0.0005
	MMS	100 mg/kg	22	83	3.8	21	25	≪0.0005
	ENU	25 mg/kg	18	57	3.2	30	53	≪0.0005
	Control	0	59	337	5.7	18	5.3
	SOA	20 mg/kg	17	56	3.3	16	29	≪0.0005
	Corn oil control	0.2 ml	10	51	5.1	2	3.9
	BaP	150 mg/kg	10	32	3.2	20	63	≪0.0005
	TCE	200 mg/kg	18	41	2.3	13	32	<0.005
	BEN	200 mg/kg	15	48	3.2	13	27	<0.01
p−/p−	Control	0	30	152	5.1	0	0
	X-rays	100 cGy	5	31	6.2	0	0
	BaP	150 mg/kg	2	6	3.0	0	0
pun/p−	Control	0	15	91	6.1	6	6.6
	BaP	150 mg/kg	3	9	3	7	78	<0.0001

Mice homozygous for pink-eyed dilution unstable (C57BL/6J p^un/p^un) were used to determine the frequency of revertant spots on their coat in response to carcinogen treatment as described (18). Data for x-rays for p^un/p^un were taken from Schiestl et al. (18) for comparison. Control animals C57BL/6J p⁻/p⁻ and C57BL/6J p^un/p⁻ were used, and control counts were taken at the time the exposures were performed.