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Table 4 Workplace asbestos exposure and bladder cancer in men from the NECSS, 1994–1997

From: Silica and asbestos exposure at work and the risk of bladder cancer in Canadian men: a population-based case-control study

Asbestos exposure groups

Cases

Controls

Minimal a

Full b

N

%

N

%

OR (95% CI)

OR (95% CI)

Ever exposed to asbestos

 Never

538

26.7

1209

59.9

1.00

1.00

 Ever

120

6.0

151

7.5

1.58 (1.20–2.08)

1.32 (0.98–1.77)

  ≥ 20 years ago

44

 

36

 

2.51 (1.57–4.03)

2.04 (1.25–3.34)

  ≥ 40 years ago

84

 

105

 

1.64 (1.19–2.25)

1.26 (0.90–1.78)

Highest attained concentration of exposure to asbestos

 Unexposed

538

26.7

1209

59.9

1.00

1.00

 Low

106

5.3

134

6.6

1.55 (1.17–2.07)

1.29 (0.95–1.76)

 Medium/ High

14

0.7

17

0.8

1.80 (0.85–3.81)

1.56 (0.73–3.32)

 p-trend

    

< 0.001

0.07

Highest attained frequency of exposure to asbestos

 Unexposed

538

26.7

1209

59.9

1.00

1.00

  < 5%

4

0.2

10

0.5

0.79 (0.24–2.63)

0.63 (0.18–2.15)

 5–30%

107

5.3

122

6.1

1.75 (1.31–2.35)

1.45 (1.06–1.98)

  ≥ 30%

9

0.5

19

0.9

0.92 (0.40–2.10)

0.90 (0.39–2.08)

 p-trend

    

< 0.001

0.08

Duration of exposure to asbestos (years)

 Unexposed

538

26.7

1209

59.9

1.00

1.00

  < 9

45

2.2

46

2.3

1.90 (1.22–2.95)

1.69 (1.08–2.66)

 9 - < 25

39

1.9

51

2.5

1.57 (0.99–2.47)

1.26 (0.78–2.02)

  ≥ 25

33

1.6

51

2.5

1.27 (0.79–2.03)

1.04 (0.64–1.69)

 Unknown

3

0.2

3

0.2

  

 p-trend

    

< 0.001

0.07

Duration of exposure at low concentrations of asbestos (years)

 Unexposed

547

27.1

1221

60.5

1.00

1.00

  < 10

44

2.2

43

2.1

1.98 (1.26–3.11)

1.75 (1.10–2.77)

 10 - < 24

33

1.6

44

2.2

1.43 (0.88–2.33)

1.13 (0.68–1.87)

  ≥ 24

31

1.5

49

2.4

1.30 (0.80–2.10)

1.05 (0.63–1.73)

 Unknown

3

0.2

3

0.2

  

 p-trend

    

< 0.001

0.11

Duration of exposure at medium/high concentrations of asbestos (years)

 Unexposed

644

31.9

1343

66.6

1.00

1.00

  < 7

5

0.3

8

0.4

1.61 (0.50–5.19)

1.39 (0.43–4.46)

  ≥ 7

9

0.5

9

0.5

1.75 (0.66–4.64)

1.54 (0.58–4.14)

 p-trend

    

0.14

0.36

Cumulative exposure to asbestos

 Unexposed

538

26.7

1209

59.9

1.00

1.00

 Lowest tertile

45

2.2

47

2.3

1.92 (1.24–2.99)

1.69 (1.07–2.65)

 Middle tertile

37

1.8

48

2.4

1.47 (0.93–2.34)

1.22 (0.76–1.97)

 Highest tertile

35

1.7

53

2.6

1.35 (0.85–2.14)

1.13 (0.70–1.82)

 Unknown

3

0.2

3

0.2

0.01

0.23

 p-trend

      
  1. a Adjusted for province of residence, age at interview, proxy respondent and cigarette pack-years
  2. b Adjusted for province of residence, age at interview, proxy respondent, cigarette pack-years, highest attained concentration of diesel exposure, ever exposed to mineral/lube oil at work