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Standards
and Regulations
- Standards and regulations
have been established to limit the use of I-131 for medical purposes
and the concentration of I-131 released into the environment.
Environmental
Protection Standards
The United States (FDA
and EPA) and the World Health Organization (WHO) have issued standards
that limit the amount of contamination in food, water, and air.
Table 3 provides a summary
of standards for environmental and occupational exposures to I-131.
The FDA food concentration guidelines both (a) restrict the flow
of contaminated food out of an affected area into the regional or
global food supply and (b) set limits on local consumption of affected
food and water. If limits are exceeded for the local population,
uncontaminated food should be provided from outside the affected
area. This also applies to drinking water with I-131 levels above
EPA limits.
Occupational limits
for radionuclide exposure address ingestion, inhalation, and external
exposure and are set by the Nuclear Regulatory Commission (NRC)
for NRC licensees and by the Department of Energy for DOE facilities.
The NRC limits for I-131 are as follows:
- 2 ×10-8
µCi/mL (for occupational air exposure)
- 2 ×10-10
µCi/mL (for effluent air to which the public could be exposed)
- 1 ×10-6
µCi/mL (in effluent water), and
- 1 ×10-5
µCi/mL (for monthly average releases to sewers from medical
facilities).
These NRC limits are
intended to ensure that no worker exceeds 50 mSv (5 rem) of I-131
to the whole body or 500 mSv (50 rem) to the thyroid, and that no
member of the public exceeds 1 mSv (0.1 rem) to the whole body.
Table
3. Summary of Recommended Maximum Concentrations
of I-131 in Specific Media and for Occupational Exposure
| Agency |
Media |
Standard |
| U.S.
Environmental Protection Agency |
Drinking
water |
4
Becquerels per liter
(108 pCi/L) |
|
|
| Air |
100
pCi/m3 |
| |
|
|
| Food
and Drug Administration |
Food
in commerce
(derived intervention level)* |
170
Becquerels per kilogram
(4,600 pCi/kg) |
| |
|
|
|
|
|
| NRC,
DOE, OSHA, National Council on Radiation Protection and
Measurement (NCRP), and International Commission on Radiological
Protection (ICRP) |
Annual
occupational exposure limits† |
50
mSv (5 rem) for whole body dose
500 mSv (50 rem) for thyroid dose |
|
*Foods
destined for general consumption and also for infant milk
and drinking water.
†Additional limits of 100 mSv (10 rem) over 5 years or
a cumulative dose limit of 10 mSv (1 rem) times age in
years (ICRP). |
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