UPTAKE OF NICOTINE IN HAIR DURING CONTROLLED ENVIRONMENTAL AIR EXPOSURE TO NICOTINE VAPOR - EVIDENCE FOR A MAJOR CONTRIBUTION OF ENVIRONMENTAL NICOTINE TO THE OVERALL NICOTINE FOUND IN HAIR FROM SMOKERS AND NONSMOKERS

Hair from smokers and non-smokers has been exposed in a dynamic exposu re chamber to air nicotine concentrations ranging from 1.5 to 45 and f rom 20 to 2000 mu g/m(3) for 8 weeks and 72 hr, respectively. Accumula ted hair nicotine was quantified by GC/MS. Hair was also collected for direct measurements of nicotine in 0-2, 2-4 and 4-6 cm segments from the scalp. Human hair showed a high affinity for air nicotine and the chamber experiments revealed a linear relationship between the initial hair uptake rates of nicotine and the duration of exposure at all air nicotine concentrations applied. Hair nicotine uptake rate decreased with time after 4 to 6 weeks exposure to 15 and 45 mu g/m(3) air conce ntrations of nicotine, but not to the 1.5 mu g/m(3) nicotine concentra tion. Ratio between the hair uptake rate of nicotine and the applied a ir concentration of nicotine decreased with increasing air concentrati ons of nicotine. Segment analysis of hair revealed an outward increasi ng gradient of nicotine in hair. Hair uptake pattern of air nicotine s uggests the uptake to be governed by an equilibrium between nicotine i n air and nicotine on the hair surface, possibly combined with a slowe r diffusion process of nicotine from the hair surface into the hair co re. The hair segment analysis of nicotine indicates that environmental nicotine is the dominating contributor to the overall nicotine found in hair bath from smokers and non-smokers.