Table 7. Unit risks of lung cancer mortality and effective concentrations associated with lifetime occupational exposurea to Cr(VI) from Cox models, controlled for smoking.
| Regression | Exposure lag (years) | EC10 (μg/m3)b | LEC10 (μg/m3)c | Unit riskd | 95% CI for unit risk |
|---|---|---|---|---|---|
| Exponential Cox | 0 | 123.2 | 18.4 | 0.000494 | (0.000314, 0.00338) |
| 5 | 131.7 | 98.2 | 0.000460 | (0.000281, 0.000618) | |
| 10 | 152.5 | 109.1 | 0.000395 | (0.000213, 0.000553) | |
| 15 | 191.7 | 127.6 | 0.000311 | (0.000128, 0.000468) | |
| Linear Cox | 0 | 64.4 | 30.6 | 0.00166 | (0.000713, 0.00349) |
| 5 | 70.6 | 33.4 | 0.00151 | (0.000639, 0.00320) | |
| 10 | 90.1 | 42.7 | 0.00119 | (0.000474, 0.00250) | |
| 15 | 123.2 | 56.4 | 0.000869 | (0.000300, 0.00190) |
a
Continuous occupational exposure (8 h/day, 240 days per year) from age 20 to 65.
b
EC10 is the estimated occupational exposure level associated with an additional lifetime lung cancer mortality risk of 0.1.
c
LEC10 is a lower 95% confidence limit for EC10.
d
Unit risk is the estimated additional lifetime risk from occupational exposure to 1 μg/m3. Both regressions included the three employees with the highest exposures.