Table 2 Parental occupational social contact and risk of childhood ALL, the Northern California Childhood Leukaemia Study, 1995–2002

From: Parental social contact in the work place and the risk of childhood acute lymphoblastic leukaemia

 

Total ALL

c-ALL

Parental occupational contact level

Case/control

OR (95% CI) a

Case/control

OR (95% CI) a

Paternal

 Low

194/223

Reference

106/122

Reference

 Medium

41/66

0.95 (0.59–1.54)

24/39

1.18 (0.61–2.30)

 High

59/87

0.92 (0.61–1.39)

35/55

0.90 (0.52–1.56)

Occupational social contact months (tertiles) b

 0–30.8

113/125

Reference

60/69

Reference

 30.9–36.9

105/128

1.06 (0.70–1.60)

57/72

1.06 (0.60–1.88)

 37.0 or more

76/123

0.95 (0.62–1.48)

48/75

1.16 (0.65–2.08)

Every 1 month increment

 

0.999 (0.990–1.007)

 

1.002 (0.991–1.013)

Maternal

 Low

169/214

Reference

98/121

Reference

 Medium

25/31

1.56 (0.86–2.85)

13/14

1.77 (0.75–4.20)

 High

99/129

1.14 (0.81–1.59)

53/79

1.03 (0.64–1.64)

Occupational social contact months (tertiles) b

 0–9.7

124/125

Reference

72/66

Reference

 9.8–36.4

76/108

0.91 (0.60–1.39)

43/60

0.84 (0.48–1.46)

 36.5 or more

93/141

0.92 (0.61–1.40)

49/88

0.70 (0.40–1.21)

Every 1 month increment

 

0.999 (0.992–1.006)

 

0.995 (0.985–1.004)

Combined parental c

 Low

113/135

Reference

64/69

Reference

 Medium

45/62

1.34 (0.81–2.23)

28/36

1.62 (0.80–3.28)

 High

135/177

1.21 (0.84–1.73)

72/109

1.10 (0.67–1.81)

Occupational social contact months (tertiles) b

 0–47.4

135/125

Reference

74/60

Reference

 47.5–73.0

77/131

0.69 (0.46–1.04)

43/77

0.69 (0.41–1.16)

 73.1 or more

81/118

1.05 (0.67–1.65)

47/77

0.87 (0.47–1.60)

Every 1 month increment

 

0.999 (0.993–1.004)

 

0.997 (0.990–1.005)

  1. ALL=acute lymphoblastic leukaemia; c-ALL=common acute lymphoblastic leukaemia; CI=confidence interval; OR=odds ratio.
  2. aThe ORs were adjusted for annual household income, birth order, total child-hours spent in day care, and the number of other children in household before the index child attended first grade in school using conditional logistic regression.
  3. bOccupational social contact months=(1.0 × months of employment with low social contact)+(1.5 × months of employment with medium social contact)+(2.0 × months of employment with high social contact).
  4. cThe ‘low’ exposure group in the combined parental analysis consists of children whose both parents had a low occupational contact level, the ‘high’ exposure group consists of children with either one of the parents having an occupation with high social contact level, and the remaining children are categorised as the ‘medium’ group.
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