Table 4

Risks of lung cancer mortality (1950–1999) and cancer incidence (1969–1999) and 95% CIs by category of cumulative RDP exposure and type of primary exposure, male Port Hope workers

Cumulative exposure (WLM)	Mean exposure (WLM)	Number of deaths	Number of person-years	RR* and 95% CI	p Value
Lung cancer mortality
0.00–	0	16	30688	1.00 (reference)	0.56†
0.01–	1.2	33	28666	0.80 (0.41 to 1.58)
3.5–	7.9	30	12460	1.67 (0.34 to 3.33)
15–	26.9	11	6518	1.37 (0.58 to 3.25)
50.0–626.0	177.9	9	4668	1.42 (0.53 to 3.84)
				ERR/100 WLM and 95% CI*
All workers with no mining experience	15.9	99	82999	0.21 (<−0.45 to 1.59)	0.54‡
Uranium workers	9.6	78	64880	0.39 (<−1.22 to 4.52)	0.83§
Radium workers	26.8	21	18119	0.21 (<−0.34 to 1.63)

Cumulative Exposure (WLM)	Mean exposure (WLM)	Number of cases¶	Number of person-years	RR* and 95% CI	p Value
Lung cancer incidence
0.00–	0	18	26550	1.00 (reference)	0.21†
0.01–	1.2	37	17113	0.89 (0.46 to 1.72)
3.5–	7.9	29	6723	1.80 (0.91 to 3.57)
15.0–	27.2	15	3289	2.28 (1.03 to 5.02)
50.0–590.3	161.1	9	1857	2.05 (0.77 to 5.44)
				ERR/100 WLM and 95% CI*
All workers with no mining experience	11.9	108	55531	0.77 (<−0.19 to 3.39)	0.15‡
Uranium workers	7.0	86	46094	3.33 (−0.04 to 12.94)	0.15§
Radium workers	24.0	22	9437	0.83 (<−0.30 to 3.72)

*Adjusted for age at risk, calendar year at risk and duration of employment by stratification.
†p Values of the test of linear trend based on mean values for exposure categories.
‡p Values from the likelihood ratio test comparing models with and without exposure variable.
§p Values from the likelihood ratio test for interaction by subcohort.
¶Number of cases based on the earliest cancer diagnosis where each subject could contribute at most one cancer.
ERR/100 WLM, excess relative risk per 100 WLM; RDP, radon decay products; RR, relative risk; WLM, working level months.