Health Risks of Ionizing Radiation: - Clark University

in this study, suggesting that a radon dose received
slowly is potentially more damaging than a radon
dose received quickly.
The Colorado Plateau cohort was assembled
by the US Public Health Service in the early years
of US mining (1950) and consists of 4,126 miners
with at least one month of underground experience
in the mines of the Colorado Plateau (including the
“four corners” states of Colorado, New Mexico,
Arizona and Utah). Roscoe (1997) found elevated
SMRs for several diseases in this cohort 6 . For lung
cancer and pneumoconiosis standardized rate ratios
increased with increasing exposure or duration of
employment. Stram et al. (1999) assessed the risk
patterns in this cohort with adjustments for various
cancer factors and additional adjustment for dose
measurement error. These authors found that risks
declined with exposure age (after age 54) and were
higher within the 10 or 20 years after exposure. An
Uranium Miners 105
Figure 8-2. Uranium mines in the US are predominantly located in the southwest and central parts of the country (www.
eia.doe.gov/.../page/reserves/uresarea.html).
ERR estimate of 0.0082/WLM was reported based
on a model that included a smoking term and used
adjusted doses. Hornung et al. analyzed the cohort
periodically (1987, 1998; reviewed in Hornung
2001) and have consistently shown an inverse doserate
effect and have also shown that the interaction
between smoking and radon appears to be more
than additive but less than multiplicative 7 . Hornung
(2001) gave an estimated ERR of 0.011/WLM below
age 60 with lower risk estimates for older ages. Park
et al. (2002) presented an alternative risk description
for the Colorado Plateau cohort and calculated lost
life expectancy attributable to mine work. These
authors considered death from leukemia and noncancer
respiratory diseases to be attributable to the
mine environment in addition to lung cancer 8 ; they
estimated that each year of work in an underground
mine was associated with 8-9 months of lost life
expectancy.
6 SMRs for the following diseases were significantly elevated: pneumoconiosis (24.1, 16.0-33.7), lung cancer (5.8,
5.2-6.4), tuberculosis (3.7, 1.9-6.2), chronic obstructive respiratory diseases (2.8, 1.0-3.5), emphysema (2.5, 1.9-
3.2), benign and unspecified tumors (2.4, 1.0-4.6), and diseases of the blood and blood forming organs (2.4, 1.0-
5.0).
7 The combined risk from smoking and radon was greater than (smoking risk + radon risk) but less than (smoking risk
x radon risk).
8 Significantly elevated SMRs were observed for leukemia (1.8, 1.1-2.9), tuberculosis (4.5, 2.6-7.3) and diseases of
the respiratory system (2.9, 2.6-3.3) based on US rates.