Racial and Ethnic Differences in Serum Cotinine Levels of Cigarette Smokers
Third National Health and Nutrition Examination Survey, 1988-1991

Ralph S. Caraballo, PhD; Gary A. Giovino, PhD; Terry F. Pechacek, PhD; Paul D. Mowery, MS; Patricia A. Richter, PhD; Warren J. Strauss, ScM; Donald J. Sharp, MD; Michael P. Eriksen, ScD; James L. Pirkle, MD, PhD; Kurt R. Maurer, PhD

JAMA. 1998;280:135-139.

Context.— Cotinine, a metabolite of nicotine, is a marker of exposure to tobacco smoke. Previous studies suggest that non-Hispanic blacks have higher levels of serum cotinine than non-Hispanic whites who report similar levels of cigarette smoking.

Objective.— To investigate differences in levels of serum cotinine in black, white, and Mexican American cigarette smokers in the US adult population.

Design.— Third National Health and Nutrition Examination Survey, 1988-1991.

Participants.— A nationally representative sample of persons aged 17 years or older who participated in the survey.

Outcome Measures.— Serum cotinine levels by reported number of cigarettes smoked per day and by race and ethnicity.

Results.— A total of 7182 subjects were involved in the study; 2136 subjects reported smoking at least 1 cigarette in the last 5 days. Black smokers had cotinine concentrations substantially higher at all levels of cigarette smoking than did white or Mexican American smokers (P<.001). Serum cotinine levels for blacks were 125 nmol/L (22 ng/mL) (95% confidence interval [CI], 79-176 nmol/L [14-31 ng/mL]) to 539 nmol/L (95 ng/mL) (95% CI, 289-630 nmol/L [51-111 ng/mL]) higher than for whites and 136 nmol/L (24 ng/mL) (95% CI, 85-182 nmol/L [15-32 ng/mL]) to 641 nmol/L (113 ng/mL) (95% CI, 386-897 nmol/L [68-158 ng/mL]) higher than for Mexican Americans. These differences do not appear to be attributable to differences in environmental tobacco smoke exposure or in number of cigarettes smoked.

Conclusions.— To our knowledge, this study provides the first evidence from a national study that serum cotinine levels are higher among black smokers than among white or Mexican American smokers. If higher cotinine levels among blacks indicate higher nicotine intake or differential pharmacokinetics and possibly serve as a marker of higher exposure to cigarette carcinogenic components, they may help explain why blacks find it harder to quit and are more likely to experience higher rates of lung cancer than white smokers.

From the National Center for Chronic Disease Prevention and Health Promotion (Drs Caraballo, Giovino, Pechacek, Richter, Sharp, and Eriksen) and the National Center for Environmental Health (Dr Pirkle), Centers for Disease Control and Prevention, and Batelle Memorial Institute (Messrs Mowery and Strauss), Atlanta, Ga; and the National Center for Health Statistics, Centers for Disease Control and Prevention, Bethesda, Md (Dr Maurer).

 

 

 

 

 

 
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Nicotine Metabolism and Intake in Black and White Smokers
Eliseo J. Perez-Stable, MD; Brenda Herrera, MS; Peyton Jacob III, PhD; Neal L. Benowitz, MD

JAMA. 1998;280:152-156.

Context.— Racial differences in tobacco-related diseases are not fully explained by cigarette-smoking behavior. Despite smoking fewer cigarettes per day, blacks have higher levels of serum cotinine, the proximate metabolite of nicotine.

Objective.— To compare the rates of metabolism and the daily intake of nicotine in black smokers and white smokers.

Design.— Participants received simultaneous infusions of deuterium-labeled nicotine and cotinine. Urine was collected for determination of total clearance of nicotine and cotinine, fractional conversion of nicotine to cotinine, and cotinine elimination rate. Using cotinine levels during ad libitum smoking and clearance data, the daily intake of nicotine from smoking was estimated.

Setting.— Metabolic ward of a university-affiliated public hospital.

Participants.— A total of 40 black and 39 white smokers, average consumption of 14 and 14.7 cigarettes per day, respectively, of similar age (mean, 32.5 and 32.3 years, respectively) and body weight (mean, 73.3 and 68.8 kg, respectively).

Main Outcome Measures.— Clearance (renal and nonrenal), half-life, and volume of distribution of nicotine and cotinine and the calculated daily intake of nicotine.

Results.— The total and nonrenal clearances of nicotine were not significantly different, respectively, in blacks (17.7 and 17.2 mL·min-1·kg-1) compared with whites (19.6 and 18.9 mL·min-1·kg-1) (P=.11 and .20). However, the total and nonrenal clearances of cotinine were significantly lower, respectively, in blacks (0.56 and 0.47 mL·min-1·kg-1) than in whites (0.68 vs 0.61 mL·min-1·kg-1; P =.009 for each comparison). The nicotine intake per cigarette was 30% greater in blacks compared with whites (1.41 vs 1.09 mg per cigarette, respectively; P =.02). Volume of distribution did not differ for the 2 groups, but cotinine half-life was higher in blacks than in whites (1064 vs 950 minutes, respectively; P =.07).

Conclusions.— Higher levels of cotinine per cigarette smoked by blacks compared with whites can be explained by both slower clearance of cotinine and higher intake of nicotine per cigarette in blacks. Greater nicotine and therefore greater tobacco smoke intake per cigarette could, in part, explain some of the ethnic differences in smoking-related disease risks.

From the Division of General Internal Medicine, Department of Medicine, Medical Effectiveness Research Center for Diverse Populations (Dr Perez-Stable and Ms Herrera); Division of Clinical Pharmacology and Experimental Therapeutics, Medical Service, San Francisco General Hospital Medical Center (Drs Jacob and Benowitz); and Departments of Medicine and Psychiatry (Drs Jacob and Benowitz), University of California, San Francisco.

 

 
 

 
   
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