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Table 4 Adjusted odds ratios (OR) and corresponding 95 % confidence intervals (CI) for rectal cancer and colon cancer in relation to occupational exposure to diesel emissions

From: Workplace exposure to diesel and gasoline engine exhausts and the risk of colorectal cancer in Canadian men

 

Rectal cancer (n = 840)

Colon cancer (n = 931)

Exposure metrica

Cases (%)

Controls (%)

ORb

(95 % CI)

Cases (%)

Controls (%)

ORb

(95 % CI)

Ever exposed

 No

538

(64.0)

869

(63.9)

1.00

  

595

(63.9)

869

(63.9)

1.00

  

 Yes

302

(36.0)

491

(36.1)

0.89

(0.72,

1.10)

336

(36.1)

491

(36.1)

0.90

(0.73,

1.11)

Highest attained exposure concentration

 Unexposed

538

(64.1)

869

(63.9)

1.00

  

595

(63.9)

869

(63.9)

1.00

  

 Low

212

(25.2)

377

(27.7)

0.78

(0.61,

0.99)

238

(25.6)

377

(27.7)

0.81

(0.64,

1.03)

 Medium

61

(7.3)

89

(6.5)

0.99

(0.68,

1.44)

75

(8.1)

89

(6.5)

1.09

(0.76,

1.56)

 High

29

(3.5)

25

(1.8)

1.98

(1.09,

3.60)

23

(2.5)

25

(1.8)

1.35

(0.72,

2.54)

 p-trend

0.56

        

p-trend

0.91

  

Duration of exposure (years)

 Unexposed

538

(64.5)

869

(64.4)

1.00

  

595

(64.5)

869

(64.4)

1.00

  

  > 0 to <11

99

(11.9)

157

(11.6)

0.91

(0.67,

1.24)

109

(11.8)

157

(11.6)

0.91

(0.68,

1.24)

  ≥ 11 to ≤31

112

(13.4)

166

(12.3)

0.99

(0.73,

1.35)

108

(11.7)

166

(12.3)

0.87

(0.64,

1.18)

  > 31

85

(10.2)

157

(11.6)

0.76

(0.52,

1.10)

110

(11.9)

157

(11.6)

0.86

(0.60,

1.21)

 p-trend

0.16

        

p-trend

0.31

  

Duration of exposure at high concentration (years)

 Unexposed

811

(96.7)

1335

(98.2)

1.00

  

908

(97.6)

1335

(98.2)

1.00

  

  > 0 to ≤10

16

(1.9)

13

(1.0)

1.84

(0.84,

4.05)

13

(1.4)

13

(1.0)

1.37

(0.60,

3.14)

  > 10

12

(1.4)

11

(0.8)

2.33

(0.94,

5.78)

9

(1.0)

11

(0.8)

1.34

(0.51,

3.55)

 p-trend

0.02

        

p-trend

0.39

  

Frequency of exposure

 Unexposed

558

(68.2)

910

(71.1)

1.00

  

633

(69.3)

910

(71.1)

1.00

  

 Low: 5 %

33

(4.0)

60

(4.7)

1.27

(0.76,

2.12)

43

(4.7)

60

(4.7)

1.21

(0.75,

1.94)

 Medium: 6–30 %

171

(20.9)

229

(17.9)

1.15

(0.87,

1.51)

180

(19.7)

229

(17.9)

1.10

(0.84,

1.44)

 High: >30 %

56

(6.9)

81

(6.3)

1.20

(0.80,

1.79)

57

(6.2)

81

(6.3)

0.95

(0.64,

1.41)

 p-trend

0.16

        

p-trend

0.70

  

Cumulative occupational exposurec

 Unexposed

538

(64.5)

869

(64.4)

1.00

  

595

(64.5)

869

(64.4)

1.00

  

 Lowest tertile

87

(10.4)

139

(10.3)

0.87

(0.63,

1.20)

87

(9.4)

139

(10.3)

0.85

(0.61,

1.18)

 Middle tertile

116

(13.9)

183

(13.6)

0.88

(0.65,

1.18)

130

(14.1)

183

(13.6)

0.83

(0.63,

1.11)

 Highest tertile

93

(11.2)

158

(11.7)

0.92

(0.66,

1.28)

111

(12.0)

158

(11.7)

0.98

(0.71,

1.35)

 p-trend

0.38

        

p-trend

0.42

  
  1. aExposures were restricted to estimates with reliability > possible; estimates with low reliability were classified as unexposed
  2. bAdjusted for age, province of residence, use of proxy respondents, BMI categories, percent change in weight from maximum lifetime weight, cigarette pack years, combined physical activity index (hours/month), alcohol consumption (servings/week), consumption of processed meat (servings/week), occupational exposure to asbestos (yes/no), occupational exposure to aromatic amines (yes/no)
  3. cCumulative metric of exposure to diesel emissions was derived from estimates of concentration of exposure, frequency of exposure and duration of employment
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Environmental Health

ISSN: 1476-069X