Hair Concentrations of Nicotine and Cotinine in Women and Their Newborn Infants

Abstract

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. 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. 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). 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.