Carcinogenic activity of some benz(a)anthracene derivatives in newborn mice.

Equimolar doses of 7-methylbenz(a)anthracene and 3 of its derivatives were given to newborn male and female Swiss mice. All 4 substances tested increased the risk of tumour development compared with that seen in control mice given the vehicle, arachis oil, only.7-Methylbenz(a)anthracene itself was the most actively tumorigenic of the compounds studied, giving rise to subcutaneous sarcomata at the site of injection, and multiple lung tumours and liver tumours. 7-Bromomethyl-12-methylbenz(a)-anthracene was similarly active in the lung and liver but evoked fewer subcutaneous sarcomata. 7-Bromomethylbenz(a)anthracene was seemingly slightly less active than either 7-methylbenz(a)anthracene or 7-bromomethyl-12-methylbenz(a)anthracene. 4-Chloro-7-bromomethylbenz(a)anthracene exhibited only marginal activity in that it slightly increased the risk of liver tumour development in male mice.