We sought to replicate findings from the Hawaii study in two studies conducted at the University of Minnesota (UMN) that collected first morning urine. UMN Study 1 (UMN-1) included 99 participants (only 2 of which were non-white) in a clinical trial [the Tobacco Reduction Intervention Program (TRIP) Study] which recruited smokers of more than 14 cigarette/day and aged 18−70 years, who were interested in reducing cigarette use in the next 30 days (13). UMN Study 2 (UMN-2) included 137 smokers (118 European Americans, 15 African Americans and 4 Asian/Pacific Islanders). Smokers of 10−40 “light” cigarettes (0.7−1.0 mg nicotine/cigarette)/day, aged 18−70, who were interested in quitting smoking were recruited via advertisement. To be eligible for both UMN studies, smokers had to: a) be in good physical health; b) have no contraindication to nicotine replacement therapy; c) be in good psychiatric health; d) not be using other tobacco products; and e) not be pregnant or nursing. In both studies, the average number of cigarettes per day was computed from a daily diary and a first morning urine sample was collected from each
