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7. REGULATIONS AND ADVISORIES URANIUM
319
7. REGULATIONS AND ADVISORIES
The international, national, and state regulations and guidelines regarding uranium in air, water, and other
media are summarized in Table 7-1.
ATSDR has derived an MRL of 8.0x10
-3
mg U/m
3
for intermediate-duration inhalation exposure to
insoluble compounds of uranium based on a NOAEL of 1.1 mg U/m
3
for renal effects in dogs (Rothstein
1949b).
ATSDR has derived an MRL of 4.0x10
-4
mg U/m
3
for intermediate-duration inhalation exposure to soluble
compounds of uranium based on a LOAEL of 0.15 mg U/m
3
for renal effects in dogs (Rothstein 1949a).
ATSDR has derived an MRL of 3.0x10
-4
mg U/m
3
for chronic-duration inhalation exposure (365 days or
more) to soluble compounds of uranium based on a NOAEL of 0.05 mg U/m
3
for renal effects in dogs
(Stokinger et al. 1953).
ATSDR has derived an MRL of 2.0x10
-3
mg/kg/day has been derived for intermediate-duration oral
exposure (and is protective for chronic-duration oral exposure) to soluble compounds of uranium based on a
LOAEL of 0.05 mg U/kg/day d for renal effects in rabbits (Gilman et al. 1998b).
According to the EPAs Integrated Risk Information System (IRIS), neither a reference dose (RfD) nor a
reference concentration (RfC) are available for uranium (IRIS 1997).
The International Agency for Research on Cancer, the U.S. Department of Human and Health Services, and
the National Toxicology Program have not classified uranium as to its carcinogenicity. According to the
Integrated Risk Information System (IRIS) database, the U.S. Environmental Protection Agency (EPA)
withdrew its carcinogenic assessment of uranium in 1993 and has not completed its evaluation and
determination of the evidence of uraniums human carcinogenicity potential (IRIS 1997).
Radiation protection recommendations for radiation workers and members of the public are provided by the
International Commission on Radiological Protection (ICRP) (ICRP 1977, 1991) and the National Council
on Radiation Protection and Measurements (NCRP) (NCRP 1987, 1993). These recommendations are not URANIUM
320
7. REGULATIONS AND ADVISORIES
regulations, but they provide the scientific basis for the development of regulations by federal agencies,
such as EPA, the U.S. Nuclear Regulatory Commission (USNRC), and the U.S. Department of Energy
(DOE), as well as by individual states.
The EPA is responsible for federal radiation protection guidance (EPA 1988c), "generally applicable"
environmental radiation standards (40 CFR 190), and regulations to implement specific statutory
requirements, such as Safe Drinking Water Act (40 CFR 141). The USNRCs regulations apply to source
materials and special nuclear material, such as enriched uranium and plutonium; the utilization of special
nuclear material, such as the operation of nuclear reactors; and the use of by-product materials, which
include wastes produced in the processing of uranium or thorium and materials made radioactive in the
utilization of special nuclear material (USNRC 1997a). The DOE has issued regulations applicable to its
facilities (DOE 1993a).
States are free to regulate radioactive materials and other sources of radiation that the Atomic Energy Act
does not give the USNRC authority to regulate. This includes sources of natural radioactivity, such as,
uranium and radium, and radiation producing machines, such as x ray machines. Section 274 of the Atomic
Energy Act (AEA) of 1954, as amended provides that states (and U.S. territories) may enter into an
agreement with the USNRC to regulate by-product materials, source materials, and special nuclear materials
(USNRC 1969). The relinquishes to these agreement states the majority of its regulatory authority over
source, by-product, and special nuclear material in quantities not sufficient to form a critical mass.
However, the USNRC retains its authority to regulate the construction and operation of production facilities
(nuclear reactors used for production and separation of plutonium or
233
U or fuel reprocess plants) and
utilization facilities (nuclear reactors used for production of power, medical therapy, research and testing);
the import of by-product, source, or special nuclear materials; and the disposal of regulated materials into
the ocean or otherwise (USNRC 1969). Currently there are 30 agreements states and 17 non-agreement
states. The governors of five states (Minnesota, Ohio, Oklahoma, Pennsylvania, and Wisconsin) have
submitted letters of intent for their states to become agreement states (ORNL 1998). The regulations
established by agreement states must be "compatible" with the USNRC's regulations, which require that the
states' regulations be at least as strict as the USNRC's regulations. The responsibilities of agreement states
also include the regulation of low-level radioactive wastes, which contain by-product materials. In non-
agreement states, the USNRC still handles all of the inspection, enforcement, and licensing responsibilities.
Figure 7-1 shows the agreement, non-agreement, and intending states. URANIUM
321
7. REGULATIONS AND ADVISORIES
Current federal and state regulations limit radiation workers doses to a total effective dose equivalent
(TEDE) of 5 rem/year and a committed dose equivalent to any organ, other than the lens of the eye, of
50 rem/year (EPA 1988c; USNRC 1995a). These limits apply to the sum of external and internal doses.
The limits are upper limits, and an important philosophy in radiation protection is to keep radiation doses as
low as reasonably achievable (ALARA).
For the control of internal doses, annual limits of intake (ALI) and derived air concentrations (DAC) have
been determined. ALIs and DACs in EPA guidance and the USNRC and DOE regulations are based on the
recommendations of the ICRP (ICRP 1979). Values of the ALIs and DACs for uranium isotopes are
presented in Table 7-1. These values are for soluble, Class D (Days) material, which has a half-time for
clearance from the pulmonary region of the lung of less than 10 days. Values of ALIs and DACs for Class
W (Weeks) and Class Y (Years) uranium are available in Appendix B to 10 CFR 20 (USNRC 1993f).
The ALI is the activity of a radionuclide that can be taken into the body in a year, by inhalation or
ingestion, without exceeding a committed effective dose equivalent (CEDE) of 5 rem/year or a committed
dose equivalent to any organ of 50 rem/year, whichever is more limiting. The total effective dose
equivalent TEDE is the sum of the CEDE and any penetrating external dose (10 CFR 20). If any external
dose is present the ALI must be reduced by a proportional amount to ensure that the dose limits are not
exceeded. For example, if a worker received an external dose of 1 rem/year, the ALI would have to be
reduced by 20% to ensure that the TEDE did not exceed 5 rem/year.
The DAC is simply the inhalation ALI divided by the volume of air that a worker is assumed to breathe in a
year (2,400 m
3
). Thus, if the average air concentration is controlled so as not to exceed the DAC, a worker
will not take in more than an ALI, and the workers dose will not exceed 5 rem CEDE or 50 rem committed
dose equivalent to any organ (ICRP 1977).
Uranium is unusual among the elements because it presents both chemical and radiological hazards. For
soluble uranium, with an
235
U enrichment no greater than 5%, limits on intakes and air concentrations for
radiation workers are based on the chemical toxicity of uranium since it is more limiting than the
radiological hazard. For this case, the USNRCs limit for a 40-hour workweek is 0.2 mg uranium per cubic
meter of air average (USNRC 1993f). URANIUM
322
7. REGULATIONS AND ADVISORIES
Between June 27, 1974 and January 18, 1989, the Occupational Safety and Health Administration (OSHA)
promulgated protective, permissible exposure limits (PELs) for more than 400 toxic substances (OSHA
1993). The OSHA PELs were established to protect employees against adverse health effects which could
result from exposure to hazardous substances found in the workplace. An employer must ensure that an
employees exposure to a toxic substance in any 8-hour work shift of a 40-hour week does not exceed the
8-hour time-weighted average (TWA) established for the substance (OSHA 1993). On January 18, 1989
OSHA promulgated more protective PELs for approximately 376 toxic substances. In July 1992, the 11
th
Circuit Court Appeals rescinded the 1989 promulgation. On March 23, 1993, OSHA resumed enforcing the
air contaminant exposure limits that were in effect prior to the issuance of the new 1989 limits (i.e., OSHA
1974 PELs). On June 30, 1993 OSHA published in the Federal Register a final rule announcing the
revocation of the 1989 exposure limits. Current OSHA general industry standards specify that an employer
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