Nitrosamine carcinogenicity: a quantitative Hansch-Taft structure-activity relationship.

Statistically significant correlations have been demonstrated between carcinogenic activity, water-hexane partition coefficients and electronic factors for an extensive series of N-nitroso compounds. Electronic factors were expressed by the Taft sigma* values of substituents on the carbon atoms alpha to the N-nitroso group. Such correlations indicate that transport of the carcinogen to its active site has an important effect on its potency. The correlations also implicate reactivity at the alpha-carbon in the determination of carcinogenic activity and point out various structural types which do not follow the general rule.