Environmental Engineering Reference
In-Depth Information
Table 2.4
Estimated Lifetime Cancer Death Risk for Environmental
Asbestos Fiber Exposure
Premature cancer deaths
per million exposed individuals
Exposure conditions
Continuous Outdoor, Lifetime Exposure
0.00001 f/cc from birth (rural)
4
0.0001 f/cc from birth (high urban)
40
School with ACBM Exposure, from Age 5-18 Years
0.0005 f/cc (average)
6
0.005 f/cc (high)
60
Public Building with ACBM Exposure, from Age 25-45 Years
0.0002 f/cc
4
0.002 f/cc
40
Occupational Exposure from Age 25-45
0.1 f/cc (OSHA PEL)
2000
Source:
Asbestos in Public and
Commercial Buildings: A Literature Review and Synthesis of Current Knowledge
From Health Effects Institute-Asbestos Research,
, Cam-
bridge, MA, 1991. With permission.
custodial, maintenance, and renovation workers may experience peak expo-
sure episodes resulting from disturbance of or damage to ACBM or distur-
bance of asbestos-containing dust. Service worker exposures are in fact sig-
nificantly higher. Based on an evaluation of asbestos fiber measurements
conducted in buildings (described previously) and estimated risk based on
linear extrapolation from effects in workers with heavy occupational expo-
sure, the Institute asbestos panel concluded that the lifetime cancer risk (both
lung cancer and mesothelioma) among general building occupants was rel-
atively low: for 20 years of exposure, 4 per million. For workers exposed to
20 f/cc for 20 years, the lifetime risk was estimated to be 1 in 5. Estimated
lifetime cancer risks for different asbestos fiber exposures are summarized
II. Radon
Radon is a naturally occurring, gas-phase element found in the earth's crust,
water, and air. Like helium, argon, neon, xenon, and krypton, radon is a
noble gas and does not react with other substances. Radon-222 is an isotope
produced as a result of the decay of radium-226. Radon-222 has a half-life
(the time period in which one-half of a given quantity of any radioactive
element will decay to the next element in a decay sequence) of 3.8 days. On
radioactive decay, radon-222 produces a series of short-lived decay products
until lead-210, a stable (long-lived) lead isotope, is produced. This decay
series, with characteristic half-lives and emissions of alpha (
α
) and beta (
β
)
particles and gamma (
γ
) rays, is summarized in
Figure 2.7
.
