title: Association between salivary cotinine and cardiovascular biomarkers among nonsmokers and current smokers: cross-sectional study of 10,081 participants.
abstract: OBJECTIVE
  Both active smoking and exposure to secondhand smoke (SHS) are associated with cardiovascular disease, but sidestream smoke contains higher levels of small particles and toxic gases than mainstream smoke. The relationship between the concentration of cotinine and a number of cardiovascular biomarkers among nonsmokers and active smokers was examined.
  
  
  METHODS
  A cross-sectional study using the Scottish Health Surveys conducted between 1998 and 2010 was undertaken. Inclusion was restricted to participants aged ≥16 years who had provided saliva and blood samples. Uni- and multivariate regression models were used to examine the relationships between the concentration of cotinine and C-reactive protein (CRP), high-density lipoprotein (HDL) cholesterol, and fibrinogen concentrations, as well as total:HDL cholesterol ratios.
  
  
  RESULTS
  Of the 10,018 eligible participants, 7,345 (73.3%) were confirmed to be nonsmokers (cotinine <15.0 ng/mL) and 2,673 (26.7%) were confirmed to be current smokers (cotinine ≥15.0 ng/mL). CRP and total:HDL cholesterol increased, and HDL cholesterol decreased, with increasing cotinine concentration across nonsmokers and smokers (all p < .001). However, there were step changes at the interface, whereby nonsmokers with a high exposure to SHS had lower concentrations of cotinine than light active smokers but comparable concentrations of CRP (p = .709), HDL cholesterol (p = .931), and total:HDL cholesterol (p = .405). Fibrinogen concentrations were significantly raised in moderate and heavy active smokers only (both p < .001).
  
  
  CONCLUSIONS
  Exposure to SHS is associated with disproportionately higher biomarkers of cardiovascular risk compared with active smoking. Protection from exposure to SHS should be a public health priority.
authors.affiliation: Institute of Health and Wellbeing, University of Glasgow, Glasgow G12 8RZ, UK.
authors.forename: L
authors.initials: L
authors.lastname: Lu
authors.affiliation: Institute of Health and Wellbeing, University of Glasgow, Glasgow G12 8RZ, UK.
authors.forename: D F
authors.initials: DF
authors.lastname: Mackay
authors.affiliation: Centre for Cardiovascular Science, University of Edinburgh, Edinburgh EH16 4TJ, UK.
authors.forename: D E
authors.initials: DE
authors.lastname: Newby
authors.affiliation: Institute of Health and Wellbeing, University of Glasgow, Glasgow G12 8RZ, UK. Electronic address: jill.pell@glasgow.ac.uk.
authors.forename: J P
authors.initials: JP
authors.lastname: Pell
mesh_terms: D000293:Adolescent; D000328:Adult; D015415:Biomarkers / Q000032:analysis; D002097:C-Reactive Protein / Q000032:analysis; D002318:Cardiovascular Diseases / Q000097:blood / Q000453:epidemiology / Q000378:metabolism*; D008076:Cholesterol, HDL / Q000097:blood; D003367:Cotinine / Q000032:analysis*; D003430:Cross-Sectional Studies; D005260:Female; D005340:Fibrinogen / Q000032:analysis; D006306:Health Surveys; D006801:Humans; D016014:Linear Models; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D012307:Risk Factors; D012463:Saliva / Q000737:chemistry*; D012606:Scotland / Q000453:epidemiology; D012907:Smoking / Q000009:adverse effects* / Q000453:epidemiology / Q000378:metabolism*; D013997:Time Factors; D014028:Tobacco Smoke Pollution / Q000009:adverse effects*; D055815:Young Adult
chemical_list: D015415:Biomarkers; D008076:Cholesterol, HDL; D014028:Tobacco Smoke Pollution; D005340:Fibrinogen; D002097:C-Reactive Protein; D003367:Cotinine
keywords: C-reactive protein; Cardiovascular diseases; Cholesterol; Fibrinogen; Secondhand smoke; Tobacco smoke exposure