CARCINOGENICITY OF 2-HYDROXYBENZO(A)PYRENE AND 6-HYDROXYBENZO(A)PYRENE IN NEWBORN MICE

Abstract

Benzo(a)pyrene (BP), 2-hydroxybenzo(a)pyrene (2-HOBP), and 6-hydroxybenzo(a)pyrene (6-HOBP) were tested for tumorigenicity by i.p. injection into newborn mice. The mice were treated sequentially with 200, 400, and 800 nmol of compound on the 1st, 8th and 15th day of life, and the animals were killed at 24 wk of age. Treatment with 2-HOBP caused about 4-fold more pulmonary tumors than BP, while 6-HOBP had little or no tumorigenic activity. Newborn mice treated with 2-HOBP, BP, and 6-HOBP had a 98, 81, and 11% incidence of pulmonary adenomas with an average of 24, 6.4, and 0.11 adenomas per mouse, respectively. In the control group, 7.5% of the animals had pulmonary adenomas with an average of 0.08 adenoma per mouse. When 25, 50, or 100 nmol of BP or 2-HOBP was applied to mouse skin once every 2 wk for 60 wk, both compounds had about the same carcinogenic activity. The importance of evaluating the carcinogenic potential of chemicals in more than one tumor system is shown. BP and 2-HOBP were tested for mutagenicity towards 2 strains of Salmonella typhimurium and towards Chinese hamster V79 cells in the presence of hepatic microsomes from rats pretreated with Aroclor 1254. The products formed during the metabolism of 2-HOBP or BP by liver microsomes had significant mutagenic activity.