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Table 3 Secondhand smoke exposure at work and breast cancer among non-smoking cases and controls from Delaware

From: Case-control study of tobacco smoke exposure and breast cancer risk in Delaware

Secondhand smoke exposure at worka cases controls odds ratiob 95% confidence Intervalb
  n % n %   
Never employed or       
not exposed at work 60 48.4 69 43.4 1.00 Reference
Any secondhand smoke exposure at work 64 51.6 90 56.6 0.80 0.49–1.32
Number of years employed at a job with secondhand smoke exposure       
   < 10 27 21.8 48 30.1 0.66 0.35–1.23
   10–19 24 19.4 27 17.0 1.02 0.52–2.00
   20–45 13 10.5 15 9.4 0.86 0.35– 2.07
Number of years employed at a job with light secondhand smoke exposure       
   < 10 17 13.7 27 17.0 0.96 0.46–1.97
   ≥ 10 13 10.5 13 8.2 1.14 0.47– 2.78
Number of years employed at a job with moderate secondhand smoke exposure       
   < 10 11 8.9 16 10.1 0.70 0.29– 1.68
   ≥ 10 17 13.7 22 13.8 1.01 0.49– 2.09
Number of years employed at a job with heavy secondhand smoke exposure       
   < 10 5 4.0 8 5.0 1.02 0.31– 3.37
   ≥ 10 7 5.6 7 4.4 1.07 0.35– 3.30
  1. a 2 non-smoking controls were missing data on exposure to smoke at work
  2. b Adjusted for age, menopausal status, body mass index (<25, 25–29, 30+), age at menarche (<12 vs. 12+), age at first live birth (nulliparous, <30, 30+), oral contraceptive use (ever vs. never), other hormone use (ever vs. never), family history of breast cancer (yes vs. no), alcohol consumption (ever drank 12 drinks in lifetime vs. had 12 drinks in lifetime but never had 1+ drink per month for 6+ months vs. ever had 1+ drink per month for 6+ months); data for adjustment factors was missing for 4 cases and 3 controls