Exposure of the Fetus, Neonate, and Nursed Infant to Nicotine and Cotinine from Maternal Smoking

The adverse effects of maternal cigarette smoking on the prenatal and postnatal development of the fetus and infant have been well documented. Greenberg et al. (April 26 issue) have shown that saliva and urine from infants exposed as smokers contained measurable amounts of nicotine and cotinine. Our results indicate that nicotine concentrations in amniotic fluid placental tissue and fetal serum all exceed corresponding maternal serum concentrations probably because of ion trapping of this basic substance in the more acidic compartments. Cotinine which is a weak base did not accumulate in the gestational fluids and tissues. On the other hand in spite of elevated concentrations of nicotine in breast milk only very small amounts of this substance were found in serum and urine from nursed infants. Passive smoking was minimized for these infants since the mothers were not allowed to smoke in the nursery. The continine concentrations in these samples were also low. Our results as well as those of Greenberg et al. indicate that measurable albeit low concentrations of nicotine and cotinine--transferred by passive smoking or in breast milk--can be detected in the infants serum saliva and urine. However much higher concentrations of these toxins were present in fetal blood amniotic fluid and placental tissue. Thus perinatal exposure to nicotine and cotinine by diaplacental and possibly paraplacental transfer appears to be quantitatively much more important than postnatal exposure by means of breast milk or inhaled air. (full text)