INTERINDIVIDUAL DIFFERENCES IN HAIR UPTAKE OF AIR NICOTINE AND SIGNIFICANCE OF CIGARETTE COUNTING FOR ESTIMATION OF ENVIRONMENTAL TOBACCO-SMOKE EXPOSURE

Hair from 80 male subjects, smokers and non-smokers, was exposed conti nously in a dynamic exposure chamber to constant nicotine vapour conce ntrations of 20, 200 or 2000 mu g/m(3) for 72 hr. Subgroups of high an d low nicotine adsorbing hair were also exposed intermittantly to envi ronmental tobacco smoke for 8 months. Air and hair concentrations of n icotine were determined by gas chromatography/mass spectrometry. The c hamber experiments demonstrated a hair nicotine uptake which followed a second order relation to the applied concentrations of nicotine, y = -0.00018x(2) + 0.715x + 1.13, r(2) = 0.99999. The function and the ex perimental points showed linearity up to an air nicotine vapour concen tration of about 200 mu g/m(3), covering the most relevant range of en vironmental exposure. An approximately 7- and 2-fold interindividual v ariation was observed in the hair uptake rate constant of nicotine vap our for the investigated material within the 10 to 90 and 25 to 75% pe rcentiles, respectively. The Factors causing this variation were not i dentified. It was shown that subject age, hair diameter and hair conte nt of eumelanin were without correlation to the rate constants of hair nicotine uptake. The exposure of subgroups of hair to environmental t obacco smoke showed similar uptake profiles of nicotine as that experi enced with exposure to pure nicotine vapour, supporting the relevance of controlled chamber nicotine vapour exposures as a relevant tool for the evaluation of hair nicotine uptake from a more complex environmen tal situation. Standardized measurements of air nicotine vapour and pa rticulate concentrations in a modern office during 8 hr periodical smo king periods, showed that the number of cigarettes smoked was a poor i ndicator for the estimation of individual exposure to environmental to bacco smoke constituents. Hair nicotine measurements so far seem to be superior to other suggested methodologies for estimation of environme ntal tobacco smoke exposure, but further studies should be initiated t o identify factors determining the rate constant of hair nicotine upta ke.