title: Exposure to different sources of second-hand smoke during pregnancy and its effect on urinary cotinine and tobacco-specific nitrosamine (NNAL) concentrations.
abstract: BACKGROUND
  To date, no research exists on the role that different sources of exposure to second-hand smoke (SHS) have on 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) and nicotine uptake, assessed via urinary 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol (NNAL) and cotinine concentrations of non-smoking pregnant women, nor the differences in NNAL concentrations among pregnant women who quit smoking in comparison to those who do not.
  
  
  METHODS
  As part of the 'Rhea' mother childbirth cohort in Crete, Greece, 1317 mother-child pairs were followed-up until delivery, while among a subsample, maternal urine was assessed for its NNAL (n=117) and cotinine concentrations (n=377).
  
  
  RESULTS
  Pregnant women who continued to smoke during pregnancy were found to have geometric mean urinary NNAL concentrations of 0.612 pmol/ml, in comparison to the 0.100 pmol/ml of ex-smokers and 0.0795 pmol/ml of non-smokers exposed to SHS. Exposure to SHS in the home was associated with a 4.40 ng/ml increase in urinary cotinine levels, while reported exposure to SHS in cars was associated with an even higher (8.73 ng/ml) increase in cotinine concentrations and was strongly related to NNAL concentrations. Exposure to SHS in the workplace and in public places was also shown to increase cotinine and NNAL concentrations. The NNAL:cotinine ratio was found to be higher among pregnant women who were exposed to SHS but did not smoke (p<0.001).
  
  
  CONCLUSIONS
  Using cotinine levels as an indicator of NNK, exposure due to SHS during pregnancy leads to an underestimation of exposure to NNK uptake. Moreover, each source of exposure contributed to the increase in cotinine levels, indicating the importance of avoiding SHS exposure from any source.
authors.affiliation: Department of Social Medicine, Faculty of Medicine, University of Crete, Heraklion, Crete, Greece. vardavas@hsph.harvard.edu
authors.forename: Constantine I
authors.initials: CI
authors.lastname: Vardavas
authors.forename: Eleni
authors.initials: E
authors.lastname: Fthenou
authors.forename: Evridiki
authors.initials: E
authors.lastname: Patelarou
authors.forename: Emmanouil
authors.initials: E
authors.lastname: Bagkeris
authors.forename: Sharon
authors.initials: S
authors.lastname: Murphy
authors.forename: Stephen S
authors.initials: SS
authors.lastname: Hecht
authors.forename: Gregory N
authors.initials: GN
authors.lastname: Connolly
authors.forename: Leda
authors.initials: L
authors.lastname: Chatzi
authors.forename: Manolis
authors.initials: M
authors.lastname: Kogevinas
mesh_terms: D016902:Air Pollution, Indoor / Q000032:analysis; D015415:Biomarkers / Q000652:urine; D003367:Cotinine / Q000652:urine*; D004781:Environmental Exposure / Q000032:analysis; D004784:Environmental Monitoring / Q000379:methods; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D009602:Nitrosamines / Q000652:urine*; D011247:Pregnancy / Q000652:urine*; D011725:Pyridines / Q000652:urine*; D057566:Self Report; D012907:Smoking / Q000652:urine; D016540:Smoking Cessation; D013048:Specimen Handling / Q000379:methods; D018454:Spouses / Q000706:statistics & numerical data; D014028:Tobacco Smoke Pollution / Q000032:analysis*
chemical_list: D015415:Biomarkers; D009602:Nitrosamines; D011725:Pyridines; D014028:Tobacco Smoke Pollution; C099565:4-(methylnitrosamino)-1-(3-pyridyl)-1-butan-1-ol; D003367:Cotinine