title: Relationships between nicotine and cotinine concentrations in maternal milk and saliva.
abstract: OBJECTIVE
  Breastfeeding may be impaired due to nicotine excreted into the milk of smoking mothers. We investigated the relationships between nicotine and cotinine concentrations in maternal milk and saliva among breastfeeding smokers.
  
  
  METHODS
  The 41 mothers reported their cigarette consumption between waking up and milk and saliva sampling. The median sampling time took place four days after delivery. Nicotine and cotinine concentrations were determined by liquid chromatography and UV detection, after a single-step saliva or three-step milk liquid-to-liquid extraction.
  
  
  RESULTS
  The median (interquartile range) concentrations in milk and saliva were 7 (6-22) and 27 (4-207) μg/L for nicotine and 24 (5-111) and 22 (4-120) μg/L for cotinine, respectively. Milk cotinine was positively associated with saliva cotinine (p < 0.0001) and cigarette consumption (p = 0.039) and inversely associated with the time since the last cigarette (p = 0.0004, model R(2) = 0.90). Milk nicotine was associated with saliva nicotine concentration (p = 0.0017) and cigarette consumption (p = 0.0023, model R(2) = 0.63).
  
  
  CONCLUSIONS
  Saliva nicotine concentration was not a very good estimate of milk nicotine concentration in breastfeeding mothers. Saliva cotinine concentration may be used instead of milk cotinine concentration to estimate tobacco or nicotine exposure among breastfed neonates or infants.
authors.affiliation: Département de Pharmacologie, Groupe Hospitalier Pitié-Salpêtrière, APHP, Paris, France.
authors.forename: Nelly
authors.identifier: http://orcid.org/0000-0002-4365-8115
authors.initials: N
authors.lastname: Jacob
authors.affiliation: Département de Biostatistique, Groupe Hospitalier Pitié-Salpêtrière, APHP, Paris, France.
authors.forename: Jean-Louis
authors.initials: JL
authors.lastname: Golmard
authors.affiliation: Département de Pharmacologie, Groupe Hospitalier Pitié-Salpêtrière, APHP, Paris, France.
authors.forename: Ivan
authors.initials: I
authors.lastname: Berlin
mesh_terms: D000328:Adult; D001942:Breast Feeding; D003367:Cotinine / Q000032:analysis*; D005260:Female; D006801:Humans; D008895:Milk, Human / Q000737:chemistry*; D009538:Nicotine / Q000032:analysis*; D012463:Saliva / Q000737:chemistry*; D012907:Smoking; D055815:Young Adult
chemical_list: D009538:Nicotine; D003367:Cotinine
keywords: Breastfeeding; Cotinine; Milk; Nicotine; Saliva