Table 2. Parental occupational social contact and risk of childhood ALL, the Northern California Childhood Leukaemia Study, 1995–2002.
|
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) | ||
ALL=acute lymphoblastic leukaemia; c-ALL=common acute lymphoblastic leukaemia; CI=confidence interval; OR=odds ratio.
The 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.
Occupational 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).
The ‘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.