Exposure to secondhand smoke and biomarkers of cardiovascular disease risk in never-smoking adults.
BACKGROUND
Exposure to secondhand smoke has been associated with a disproportionately high risk of coronary heart disease, thought to be mediated through inflammation, platelet aggregation, and/or endothelial dysfunction. The epidemiological association between objectively measured exposure to secondhand smoke and biomarkers of heart disease risk has not been investigated, however.


RESULTS
We have investigated the cross-sectional relation between secondhand smoke exposure, measured objectively as cotinine, and recognized biomarkers of heart disease risk, namely C-reactive protein, homocysteine, fibrinogen, and white blood cell count, in 7599 never-smoking adults from the Third National Health and Nutrition Examination Survey. Compared with subjects with no detectable cotinine, those with detectable but low-level cotinine (range, 0.05 to 0.215 ng/mL) had significantly higher levels of both fibrinogen (adjusted mean difference, 8.9 mg/dL; 95% CI, 0.9 to 17.0; P=0.03) and homocysteine (0.8 micromol/L; 95% CI, 0.4 to 1.1; P<0.001) but not C-reactive protein or white blood cell count. Effect estimates of similar magnitude and significance were seen in subjects in the high category of cotinine exposure (>0.215 ng/mL). The increased levels of fibrinogen and homocysteine seen in relation to secondhand smoke exposure were equivalent to approximately 30% to 45% of those seen for active smoking.


CONCLUSIONS
Passive smokers appear to have disproportionately increased levels of 2 biomarkers of cardiovascular disease risk, fibrinogen and homocysteine. This finding provides further evidence to suggest that low-level exposure to secondhand smoke has a clinically important effect on susceptibility to cardiovascular disease.
Venn
Andrea
A
Division of Epidemiology and Public Health, University of Nottingham, Clinical Sciences Bldg, City Hospital, Nottingham, NG5 1PB, UK. andrea.venn@nottingham.ac.uk
Britton
John
J
D000328:Adult; D015415:Biomarkers; D002097:C-Reactive Protein / Q000032:analysis; D002318:Cardiovascular Diseases / Q000097:blood / Q000209:etiology*; D003367:Cotinine / Q000097:blood; D003430:Cross-Sectional Studies; D005260:Female; D005340:Fibrinogen / Q000032:analysis; D006710:Homocysteine / Q000097:blood; D006801:Humans; D007958:Leukocyte Count; D008297:Male; D008875:Middle Aged; D012307:Risk Factors; D014028:Tobacco Smoke Pollution / Q000009:adverse effects*
D015415:Biomarkers; D014028:Tobacco Smoke Pollution; D006710:Homocysteine; D005340:Fibrinogen; D002097:C-Reactive Protein; D003367:Cotinine