sample="quota" bates="HK0042150" isource="ctr" decade="1970" class="ui" date="19730000" ABSTRACT Aryl hydrocarbon hydroxylase (AHH) is an inducible, microsomal enzyme involved in the metabolism of chemical carcinogens. It shows genetic variation in man, and the normal U.S. population can be divided into three separate groups having low, intermediate, and high AHH activities, with frequencies of 44.7%, 45.9% and 9.4% respectively. Fifty patients with bronchogenic carcinoma were studied and the frequencies of the three AHH groups were 4.0%, 66.0%, and 30.0%. The data indicate that susceptibility to bronchogenic carcinoma is associated with the higher levels of AHH activity.