Accumulation of nicotine in human hair during long-term controlled exposure to a low concentration of nicotine vapour.

Hair from 5 subjects were exposed in dynamic exposure chambers to air nicotine vapour for 72 hr or 12 months at concentrations of 200 or 5 micrograms/m3, respectively. Nicotine in the chamber air and human hair was determined by GC/ MS. A linear accumulation of nicotine in hair was found with time for all hairs during the long-term, low concentration exposure, with individual hair nicotine uptake rate constants ranging from 0.70 to 3.75 x 10(-3) m3/g x hr. The corresponding hair nicotine uptake rate constants during short-term, high concentration exposure, were significantly higher, ranging from 1.35 to 15.11 x 10(-3) m3/g x hr, showing, however, a highly significant linear correlation with the individual long-term exposure rate constants, r2 = 0.9961. It is indicated that long-term hair nicotine uptake rate constants calculated from controlled exposure experiments with pure nicotine vapour are adequate for estimation of individual long-term hair accumulation of nicotine from environmental tobacco smoke even at variable and intermittent exposure. Although higher than the long-term uptake rate constants, the short-term uptake rate constants seem well fitted for a differentiation between different types of hair in their ability to adsorb nicotine also during long-term exposures. The short-term uptake rate constants might also be useful parameters for establishing a reliable cut-off limit in the hair concentration of nicotine between smokers and non-smokers which otherwise seems to be overlapping.