home edit2 whole TSD November 2002 PDF format - OEHHA

1942 and December 31, 1967 with a median duration of employment of 7.2 months. A significantly
increased incidence of mortality due to lung cancer was observed in the entire cohort (47 observed
versus 34.29 expected, p < 0.05), as well as in the 2068 cohort members followed for 25 years or
more since initial employment (20 observed versus 10.79 expected, p < 0.01). When the number of
expected deaths was recalculated using 1968-1975 lung cancer mortality data, significance was lost for
the cohort overall (38.2 expected), but not for the subgroup followed for 25 years or more (13.36
expected, p ≈ 0.05) (Bayliss, 1980; MacMahon, 1977, 1978). However, significance was lost for the
subgroup when the number of expected deaths was adjusted for smoking (14.67 expected) (US EPA,
1986).
The data of Wagoner et al. (1980) was used for the quantitation of cancer potency due to inhalation
exposure despite study limitations. Human inhalation exposure is usually to beryllium oxide rather than
other beryllium salts. Animal studies utilizing beryllium oxide have used intratracheal instillation instead
of inhalation exposure. The use of the available human data therefore avoids uncertainties due to crossspecies
extrapolation, and uses the most relevant route of administration and beryllium species.
Methodology
A risk assessment was performed based on the occupational exposure study of Wagoner et al. (1980).
The narrowest range for median exposure that could be obtained on the basis of available information
was 100 to 1000 µg/m 3 . Effective dose was calculated by adjusting for the duration of daily (8 of 24
hours) and annual (240 of 365 days) exposure, and the fraction of the lifetime at risk (time from start of
employment to study termination). Smoking-adjusted expected lung cancer deaths were found to range
from 13.91 to 14.67 (based on exposure range) compared to 20 observed. Relative risk estimates of
1.36 and 1.44 were calculated and the 95% confidence limits of these estimates used to calculate the
lifetime cancer risk (Table 2). These estimates were based on one data set and a range of estimated
exposure levels and times. To account for estimation uncertainties, unit risks were derived using two
estimates each of concentration, fraction of lifetime exposed and relative risk. The listed unit risk factor
[2.4 E-3 (µg/m 3 ) -1 ] is the arithmetic mean of the 8 derived unit risks. US EPA has stated that this unit
risk may not be appropriate if the air concentration exceeds 4 µg/m 3 and should not be used under those
circumstances.
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