HAIR CONCENTRATIONS OF NICOTINE AND COTININE IN WOMEN AND THEIR NEWBORN-INFANTS

Background.-To date, no biological markers have been identified that can predict the extent of fetal exposure to the toxic constituents of cigarette smoke. A variety of xenobiotic agents have been shown to accumulate in growing hair. Patients and Methods.-We measured maternal and neonatal hair concentrations of nicotine and cotinine in 94 mother-infant pairs. Mothers who were active smokers, nonsmokers, and passive smokers and their infants were included. Results.-Mothers who were active smokers (n=36) had mean (SEM) hair concentrations of 19.2 (4.9) ng/mg for nicotine and 6.3 (4.0) ng/mg for cotinine, significantly higher than concentrations in nonsmokers (n=35) (1.2 [0.4] ng/mg for nicotine and 0.3 [0.06] ng/mg for cotinine, P<.0001). Infants of smokers had mean hair concentrations of 2.4 (0.9) ng/mg for nicotine (range, 0 to 27.3 ng/mg) and 2.8 (0.8) ng/mg for cotinine (range, 0 to 12.2 ng/mg), significantly higher than concentrations in infants of nonsmokers (0.4 [0.09] ng/mg for nicotine and 0.26 [0.04] ng/mg for cotinine, P<.01). Mothers with passive smoke exposure and their infants (n=23) had significantly higher hair concentrations of nicotine (3.2 [0.8] ng/mg for mothers and 0.28 [0.05] ng/mg for infants) and cotinine (0.9 [0.3] ng/mg for mothers and 0.6 [0.15] ng/mg for infants) than nonsmoking mothers and their infants (P<.01). There was a significant correlation between maternal and neonatal hair concentrations of nicotine (r=.49, P<.001) or cotinine (r=.85, P=.0001). Conclusions.-This is the first biochemical evidence that infants of passive smokers are at risk of measurable exposure to cigarette smoke. Hair accumulation of cigarette smoke constituents reflects long-term systemic exposure to these toxins and therefore may be well correlated with perinatal risks.