Plasma nicotine and cotinine concentrations in habitual smokeless tobacco users

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Abstract
Plasma nicotine and cotinine levels were measured in habitual users of smokeless tobacco. The subjects were 12 male college students who regularly used smokeless tobacco (11 dipped snuff and 1 chewed tobacco) and did not smoke cigarettes. Subjects abstained from tobacco use overnight and blood was drawn at 0800 h and again after a single day of ad lib consumption of their own tobacco product. Subjects recorded the times at which tobacco was used and the remainder product was weighed. Plasma samples were analyzed by GLC and radioimmunoassay (RIA) technique. Subjects consumed about 1/3 of a can of moist ground snuff (10.8 g) in 8 dips spaced throughout the day. Nicotine absorption was observed and an increase in mean plasma concentration from 2.9 ng/ml after overnight abstinence to 21.6 ng/ml after 6-8 h ad lib consumption was recorded. Plasma cotinine concentrations rose from a morning mean of 137.3 ng/ml to an afternoon mean of 197.2 ng/ml, concentrations that are typical of those reached in regular cigarette smokers. Subjects fell into 2 subgroups by post hoc analysis: 2/3 absorbed substantial amounts of nicotine and 1/3 appeared to have almost no absorption. Subjective effects of tobacco use were not marked; there was little perception of physiologic changes, stimulation or feelings of relaxation/satisfaction. Pharmacologic effects, comparison of results from GLC and RIA methodologies and implications for health behaviors were discussed.