Civil Engineering Reference
In-Depth Information
Source: USEPA NIRS Survey, 1985.
Note: State averaging of data may obscure local variations in radon levels.
Fig. 2-3.
General patterns of radon occurrence in groundwater in the United States (
Source:
Reference 23)
developing internal organ cancers, primarily stomach cancer; however, this risk is
smaller than the risk of lung cancer due to inhaled radon from drinking water. Based
on an NAS report, EPA estimates that radon in drinking water causes about 168 deaths
per year: 89 percent from lung cancer caused by breathing radon released to indoor
air from water and 11 percent from stomach cancer caused by consuming water con-
taining radon.
20
Radium
Occurrence
Radium is found primarily in groundwater. Based on review of com-
pliance records for drinking water systems, one survey estimated that 500 of the ap-
proximately 60,000 public drinking water supplies have radium levels that exceed 5
pCi / L. The largest concentration that has been measured in a public drinking water
system is approximately 100 pCi / L; the mean for
226
Ra is about 0.4 pCi / L and the
mean for
Ra is about 0.7 pCi / L.
20
Although the occurrences of
228
Ra are independent (they occur in two
different radioactive series), in general, their nationwide distributions with respect to
concentration are somewhat similar. The highest levels are found in the Piedmont
region of North Carolina; South Carolina and Georgia; the midwestern area of Iowa,
northern Illinois, and southern Wisconsin; and the ''four corners'' region in the West.
20
226
Ra and
228
Health Effects
Radium, biochemically similar to calcium and barium when in-
gested, concentrates in the bone. The health effects of ingested radium are well doc-
umented and are largely based on the studies of radium watch dial painters in the early
part of this century who came into oral contact with radium as part of the work process.
