Table 6.
Relative risks of lung cancer mortality by categories of radon exposure, joint cohort restricted to < 100 WLM
| Cumulative radon exposure (WLM) | Mean cumulative exposure (WLM)a | Lung cancer deaths | Person-years | Relative risk (MLE) | 95% CI | LR statistic | Degrees of freedom | P Value (Linear trend) |
|---|---|---|---|---|---|---|---|---|
| 0.0 | 0.0 | 32 | 72,455 | 1.00 | 51.08 | 7 | < 0.001 | |
| > 0.0–2 | 1.5 | 39 | 109,620 | 0.83 | 0.51–1.34 | |||
| 3–9 | 6.0 | 51 | 84,256 | 0.94 | 0.60–1.50 | |||
| 10–19 | 14.6 | 48 | 44,444 | 1.41 | 0.90–2.25 | |||
| 20–39 | 29.6 | 63 | 34,915 | 1.62 | 1.06–2.52 | |||
| 40–59 | 49.5 | 66 | 21,157 | 2.02 | 1.31–3.18 | |||
| 60–79 | 69.4 | 64 | 17,147 | 2.39 | 1.55–3.76 | |||
| 80–100 | 88.7 | 45 | 10,244 | 2.32 | 1.45–3.76 | |||
| Total | 408 | 394,236 |
Deviance 2607.234
Relative risks were stratified by sub-cohort (3 categories) and age at risk (12 categories)
P value of the test of linear trend is based on mean values for exposure categories
Workers with zero cumulative radon exposures are included in the 0.0 WLM category; workers who had cumulative exposures ranging from 0.010 to 2.999 WLM are included in the > 0.0–2 WLM category
WLM working-level months, CI confidence interval, MLE maximum likelihood estimate, LR likelihood ratio
aMean cumulative radon exposure (5-year lagged, WLM) weighted by person-years at risk