The Urinary Cotinine Levels of Infants and the Determinants
Gonca Yılmaz1, Candemir Karacan1, H. Tanju Besler2, Kadriye Yurdakök3,
1Dr. Sami Ulus Children’s and Maternity Training and Research Hospital, and 2Department of Nutrition and
Dietetics, Faculty of Health Sciences, and 3Department of Pediatrics, Hacettepe University Faculty of Medicine, Ankara,
The aim of this study was to determine the effect of the route of tobacco
smoke exposure on urinary cotinine levels of infants.
A cross-sectional analysis was done on 254 six-month-old infants. The infants
were grouped according to the route of tobacco smoke exposure. The urinary
cotinine/creatinine ratios were determined.
Forty-nine percent (124/254) of mothers were smokers. Urinary cotinine
levels in infants of smoking mothers were statistically significantly higher
than levels in infants of non-smoking mothers. The highest mean cotinine/
creatinine level was found in the breast-milk-exposed group. Linear regression
analysis showed that maternal smoking increased urinary cotinine level by
541 times and breastfeeding increased it by 171 times, whereas early start
of formula feeding decreased it by 63 times.
Tobacco exposure by breastfeeding may be more harmful than other routes
of exposure. Mothers should be encouraged to stop smoking during the
breastfeeding period even if they avoid exposing their infants to passive