ML20029C586
| ML20029C586 | |
| Person / Time | |
|---|---|
| Issue date: | 03/29/1994 |
| From: | Taylor J NRC OFFICE OF THE EXECUTIVE DIRECTOR FOR OPERATIONS (EDO) |
| To: | |
| References | |
| SECY-94-087, SECY-94-87, NUDOCS 9404040174 | |
| Download: ML20029C586 (33) | |
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March 29, 1994 TheCommisN-<Bn FOR:
FROM:
James M. TI - LICY ISSUE I
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Executive Di fc'YidODhd/Ot6h);
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SUBJECT:
ADDENDUM TO SECY-93-318 RE-EVALUATION OF POLICY REGARDING USE OF POTASSIUM 10DIDE AFTER A SEVERE ACCIDENT AT A NUCLEAR POWER PLANT PURPOSE:
To supplement SECY-93-318 concerning a possible change in the NRC policy regarding the use of potassium iodide (KI) as a radioprotective agent for the general public. This addendum provides a recommended staff option for Commission consideration and responds to questions raised by several Commissioners.
l PlSCUSSION:
In SECY-93-318, the staff sought Commission guidance concerning a possible change in the NRC policy regarding the use of potassium iodide as a radioprotective agent for the general public.
The paper presented three options for Commission consideration with regard to this matter:
(1) make no change in existing NRC policy, (2) await a request from the appropriate interagency group which recommends federal policy in this area to comment on or endorse any proposed guidance before changing the current NRC policy, or (3) adopt a change in NRC policy which would encourage the federal emergency planning authorities to acquire potassium iodide reserves that could be made available during a nuclear emergency.
Since the SECY paper was issued, the staff has received oral and written questions from several Commissioners regarding the benefit-cost analysis and other issues related to the stockpiling and distribution of potassium iodide.
Responses to questions raised by Chairman Selin, Commissioner Rogers and Commissioner de Planque are provided in enclosures 1, 2 and 3.
I In addition, the staff has recently engaged in preliminary dialogue with FEMA i
and HHS, who along with the NRC, are the federal agencies responsible for providing guidance to Stata and local governments concerning emergency planning, the use of radioprotective substances, and the prophylactic use of
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drugs in response to a radiological accident at a nuclear power plant. We now
Contact:
R. Woods, RES NOTE:
TO BE MADE PUBLICLY AVAILABLE 492-3908 WHEN THE FINAL SRM IS MADE F. Congel, NRR 504-1088
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The Commissioners understand that HHS and FEMA would cooperate with the NRC in working toward the adoption of a revised federal policy on KI.
Accordingly, the staff is proposing a fourth option for Commission consideration.
4.
NRC, in coordination with HHS and FEMA, revise current federal KI policy i
to make KI available to the States Although a. reactor accident requiring KI is unlikely and KI is only effective as a protective measure for the dose to the thyroid due to radioactive iodine, the cost to purchase and stockpile amounts sufficient to administer to populationg within five miles of operating nuclear power plants is relatively low.
Consequently, it appears j
prudent to stockpile KI for limited populations located close to the operating nuclear power plants.
This option represents an interoffice consensus and is recommended by the staff.
If the Commission chooses this option, the staff will work
)
directly with FEMA and HHS to revise the Federal policy regarding stockpiling KI for possible use in a radiological emergency. The revised policy would state that KI will be purchased by the federal government (most likely the NRC or FEMA) and made available through FEMA to the States. While NRC encourages the stockpiling of KI, the decision to stockpile, distribute and use KI would be the responsibility of the individual States' emergency planning authorities. At the option of the States, procedures incorporating the use of KI in State emergency plans
)
would be developed with the assistance of FEMA.
The details regarding-this option would be developed and coordinated through the Federal Radiological Preparedness Coordinating Committee.
l 2 The unit cost to purchase KI is $0.05 per pill.
Since a KI supply sufficient for one person consists of 10 pills, the cost to purchase a KI stockpile is $0.05 x 10 - $0.50 per person to be protected by that stockpile.
There are 598,017 persons living within' 5 miles of the 55 nuclear power plant 1
sites listed in the cost-benefit reevaluation report, including populous sites such as Indian Point, Zion, THI, Limerick, etc. There are 72 nuclear power plant sites in the U.S.
Thus, if all States were to request KI a conservative estimate of the total population within 5 miles of any U.S. nuclear power plant site (i.e., the number of persons proposed to be protected by the i
stockpile) is 598,017 x 7?/55 - 782,859 persons, and the initial cost of providing a KI stockpile for those persons is $0.50 x 782,859 - $391.400.
Since KI has a shelf life of it. least five years, the yearly cost would not be expected to exceed $391,400/5 - $78,300 per year, which is equal to $0.10 per person per year.
In fact, if only plume exposures are considered only one or two pills would likely be needed, reducing the cost even further.
0 s.
39 The Commissioners COORDINATION:
The Office of 'the General Counsel has reviewed this proer and has no legal objection. Peter Crane, who filed a Differing Professional Opinion on this matter, concurs in the staff's recommendation.
RECOMMENDATION:
The staff recommends option 4 in which the NRC, in coordination with HHS and FEMA, would revise current federal KI policy to make KI available to the States.
a es M. Ta r
ecutive Director for Operations
Enclosures:
1.
Responses to Chairman Selin's Questions 2.
Responses to Commissioner Rogers i
Questions j
3.
Responses to Commissioner de Planque's Questions I
Commissioners' comments or consent should be provided directly to the Office of the Secretary by COB Wednesday, April 13, 1994.
Commission Staff Office comments, if any, should be submitted 1
to the Commissioners NLT Wednesday, April 6, 1994, with an information copy to the Office of the Secretary.
If the paper is of such a nature that'it_ requires additional review and comment, the Commissioners and the Secretariat should be apprised of when comments me.y be expected.
DISTRIBUTION:
Commissioners OGC OCAA OIG OPA OCA OPP EDO SECY l
i i
I ENCLOSURE 1 4
l l
RESPONSES TO CHAIRMAN SELIN'S OUESTIONS AT FIRST BRIEFING 1.
Were the most appropriate sequences considered' Provide details concerning the sequences of events analyzed.
)
Ben 1v:
The four release categories considered represent ALL l
the accidents for Surry Nuclear Plant in which significant quantities of radioactivity are released.
[In fact, since one of the four (RSUR-3) did not involve a containment fail're or u
bypass, it didn't contribute significantly and has been deleted from these responses.)
These release categories include internal and external events, as shown:
Internal Events RSUR-1 Sta. Blackout [LOSP CDF=4E-05 2.9E-07
\\Dsls. Fai (6 hr) '
Cont. Bypass ATWS LOCA RSUR-2 External Events 2.4E-06 W%
(12 hr)
Trans. w LOSP Seismic SLOCA LLOCA CDF=1.3E-04 Fire Trans. w RCP
\\*-
seal fail.
RSUR-4 PORV Stk. Ope l
1.6E-06 4
(1 hr)
The above encompasses thousands of individual sequences, some leading to one of the three releases shown, but most leading to core damage but NOT to release.
l Two example sequences, in " Readers' Digest" narration format, 1
are:
a)
Station Blackout Caused by Internal Events - Loss of on-site and off-site ac power results in the unavailability of the high-pressure injection system, the containment spray system, the inside and outside 1
~
containment spray recirculation systems, and the motor-driven auxiliary feedwater (AFW) pumps.
While the loss of all ac power does not affect instrumentation at the start of the station blackout, a long duration station blackout leads to battery depletion and subsequent loss of vital instrumentation.
Battery depletion was concluded to occur after approximately 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br />.
The ability to subsequently provide decay heat removal with the turbine-driven AFW pump is lost because of the loss of all instrumentation and control power.
Approximately 3 hours3.472222e-5 days <br />8.333333e-4 hours <br />4.960317e-6 weeks <br />1.1415e-6 months <br />, beyond the time of battery depletion, were allowed for restoration of ac power before core encovery would occur.
b)
Seismically Initiated Station Blackout /LOCA -
Seismically initiated loss of off-site power plant transients may lead to cooling system failures inclusive of the reactor coolant pump seals.
The failure of coolant pump seals results in a reactor coolant pump seal LOCA.
Concurrently, station blackout also results in the unavailability of the high pressure injection (HPI) system, as well as the auxiliary feedwater motor-driven pumps, the containment spray system, and the inside and outside spray recirculation systems.
Continued coolant loss through the failed seals, with unavailability of the HPI system, leads to core uncovery.
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2.
How many thyroid-related health effects would result from the sequences considered, without KI available?
How many would occur, even with KI stockpiled or predistributed?
In what fraction of the population do these health effects occur?
Reply:
Thyroid-relatet health effects among the 10.700 cersons j
within 5 miles of the average US LWR (corrected for all factors to be discussed in these responses) for the stockpilina option are:
Release Thyroid Cancer Thyroid Category Nodules Hypothyroid.
(option)
Non-Fatal Fatal PSUR-1:
No KI 123 14 361 105 KI stkold B_Q R
211 10_5 Avoided 43 5
120 0
RSUR-2:
No KI 52 6
155 31 KI stkold 36 1
112 11 Avoided 16 2
43 0
RSUR-4:
No KI 47 5
139 33 KI stkold 47 5
129 3_3_
3 Avoided 0
0 0
0 3
Thyroid-related health effects among the 10,700 persons within 5 miles of the average US LWR (corrected for all factors to be discussed in these responses) for the predistribution option are:
Release Thyroid Cancer Thyroid Category Nodules Hypothyroid.
(option)
Non-Fatal Fatal RSUR-1:
No KI 123 14 361 105 KI nreds_t il s
152 125 Avoided 76 8
201 0
RSUR-2:
No KI 52 6
155 31 KI nredst 21 2
B_4_
21 Avoided 26 3
71 0
RSUR-4:
No KI 47 5
139 33 KI Dredst 12 2
60 33 Avoided 28 3
79 0
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Thyroid-related health effects among the 10.700 cersons within 5 miles of the average US LWR presented in the original Draft i
Report (without application of any of the correction factors to be discussed in these responses) for the stockpilina option are:
)
l Release Thyroid cancer Thyroid Category Nodules Hypothyroid.
(option)
Non-Fatal j
Fatal RSUR-1:
No KI 123 14 361 105 KI stkold is 2
51 s
Avoided 107 12 303 99 RSUR-2:
No KI 52 6
155 31 KI stkold 1A 2
12 2
Avoided 38 4
103 28
)
RSUR-4:
No KI 47 5
139 33 KI stkold 2
1 25 1
Avoided 40 4
114 32 (Note that avoided thyroid problems were not calculated in the Draft Report for the predistribution option) 3.
What was the whole-body exposure of persons with those effects?
Was KI credited with avoiding thyroid-related health effects in persons who would die from whole-body exposure?
Reply:
In RSUR-1, at the plume centerline within 5 miles'of the plant, maximum whole body doses are predicted to be 870 rem-(these doses decrease at greater distances and also decrease "off centerline" of the plume).
i Whole-body doses in the range of 870 rem are quite likely fatal.
However, MACCS code subtracts all radiation exposure of persons
'i who become early fatalities from the total population radiation
" pool" that is used when MACCS calculates latent health effects.
Therefore, latent health effects (including thyroid nodules, fatal and non-fatal cancers, and hypothyroidism) are not 5
calculated in persons who become early fatalities.
Thus, since they are not predicted, their avoidance due to presence of KI stockpiles is not credited as a " benefit" of the KI.
- However, two correction factors have been developed and applied to the Draft Report's C/B ratios to correct for imprecisions in the MACCS code.
These are:
a)
The Mortality Factor (MF).
Hypothyroidism's threshold exposure is such that a thyroid dose leading to hypothyroidism would also involve a whole body exposure that could prove to be fatal.
Thus, the value of KI in eliminating hypothyroidism occurs among individuals who might die from acute whole body radiation exposure.
Accordingly, to avoid possible everlap in counting KI benefits, the benefit of eliminating hypothyroidism has been subtracted from the " Reference" cost-benefit ratio stated in the draft report.
The "MF" factor causes a
-15% to 20% increase in the C/B ratio, eliminating the possible overlap, b)
The High Dose F.: tor (HDF).
At high radiation exposures, there is a very significant decrease per unit dose in the probability of causing fatal and non-1 fatal thyroid cancer or thyroid nodules.
This is because the high doses also kill the thyroid gland's cells, destroying their ability to reproduce.
If they can't reproduce, they also can't develop nodules (cancerous or benign).
This effect is not included properly in the MACCS code.
Correction is accomplished by the High Dose Factor (HDF), which causes a ~6%
increase in the C/B ratio.
4.
How effective was KI assumed to be in preventing thyroid health problems after a nuclear release?
Reply:
The following factors were correctly taken into account.
in the Draft Report's C/B ratios:
a)
When administered before plume passage, KI is' assumed to prevent 99% of the thyroid exposure caused by inhaled radiciodides.
b)
Inhaled radiciodides cause between 90% and 95% of thyroid irradiation (I"1 is dominant, but all iodine isotopes are included).
c)
KI is NOT assumed to be effective in preventing thyroid irradiation caused by:
combined inhalation of non-radiciodides, and external exposure from plume immersion, cloud shine, and ground deposition.
6
=
Although KI would help prevent thyroid exposure from ingested radiciodides, regional populations in the US are not critically dependent on local food sources, and it is assumed that this exposure pathway can be trivialized by protective measures imposed by local health authorities to limit availability and intake of contaminated food sources.
However, correction factors have been applied to the Draft Report's C/B ratios to account for:
d)
The Availability Factor (AP).
This factor accounts for the fact that, contrary to the draft report's assumption that 100% of the population would have KI available and would take it prior to plume passage, the actual availability would be lower.
e)
The Timeliness factor (TF).
This factor accounts for the fact that time of KI administration might not be before plume passage, and thus the assumed 99%
effectiveness for preventing thyroid exposure from inhaled radiciodides would be lower.
Both of these factors are dependent upon the distribution plans (or on effectiveness of pre-distribution).
Factors calculated / assumed by the contractor are shown on page 9; page 8 shows how quantitative effects on the C/B ratio can be determined for alternate (subjectively preferred) assumptions.
5.
What costs associated with providing KI were included?
Reply:
For stockpiling, the only cost assumed in the Draft Report was purchasing and then replacing KI every 5 years.
This costs $0.10 per year per individual.
For predistribution, costs are based on Tennessee State officials' pre-distributing 3704 vials, each containing KI tablets for an entire household.
Costs included purchase of the tablets and a public relations program presenting the objectives of iodide prophylaxis, information regarding safe storage, proper usage, dosage, contraindications, etc., and attempting to establish public confidence.
Total cost was $125,000.
Assuming a five year KI shelf life and four individuals per household, cost per person per year is:
$/ person-yr = $125,000 / [(3704 x 4) x (5)) = ~$1.70 7
)
A Cost Factor (CF) of $0.10/$0.10 = 1 for stockpiling and
)
$1.70/$0.10 = 17 for predistribution was used to determine the revised numbers in these responses.
Alternative (subjectively preferred) Cost Factors can lua applied as shown below in the response to Question 6.
-1 6.
How can1one utilize different correction factors?
Reply:
This can be accomplished by use of the equation:
C/B (Ref. C/B) x (CF) x (AP) x (TF) x (MF) x (HDF)
=
where:
C/B
= the modified cost-benefit ratio Ref. C/B = the Draft-Report-derived Cost / Benefit Ratio for the 0-5 mile population:
when psychological costs are included, Ref. C/B = 2.2 when psychological costs are excluded, Ref. C/B = 21 S Cost of nrovidina KT ner individual-vrd 7,
$0.10 i
AF =
100%
% of population having access to KI 99%
TF =
% efficiency in thyroid dose reduction.
l Avoided Costs: Nodules. Cancers. Hvnothyroidism gp,
Avoided' Cost for Nodules and Cancers 1
= 1.20 if benefits from avoided psychological costs are included i
1.14 if benefits from avoided psychological costs are not included MACCS Uncorrected Ponulation Thyroid Dose HDF
Corrected Population Thyroid Dose 1.06
=
8
Using the best-estimates already discussed, cost-benefit ratios for the stockpiling option and the predistribution option are:
Ref. C/B MF Modified C/B K! Option CF AF' TF2 HDF Psy No Psy Psy No Psy Psy No Psy Stockpi.
2.2 21 1
1,67 2.3 1.20 1.14 1.06 11 99 Predist.
2.2 21 17 1,42 1
1.20 1.14 1.06 69 624 For the stockpiling option, as a central value, it is assumed that 60% of the population can be provided with KI, so that AF = 100% / 60% = 1.67. For the predistribution option, considering the Tennessee experience, it is assumed that 70% of the population has access to predistributed KI, so that AF = 100% / 70% = 1.42.
2 For the stockpiling option: For RSUR-1 and RSUR-2, a reasonable estimate assumes a modest delay in KI administration that, on the average, confers a 70% reduction in thyroid exposure. For RSUR-4, the short interval to release time and brief duration preclude the likelihood of any protective action by KI. Based on the relative contribution to the total avoidable thyroid effects by these three release categories, an overall percent of thyroid dose reduction of 43% is estimated. Thus, TF = 99 % / 43 % = 2.3. For the predistribution option, all individuals who have access to their predistributed KI are assumed to take it before plume arrival, so that the achieved overall dose reduction factor is 99%. Thus, TF = 99% /
99 % = 1.0.
7.
Did the analyses assume evacuation? What effects did (would) evacuation have on the C/B results?
Reply:
The Draft Report's analyses assumed NO evacuation and normal activities (means 75% sheltered, indoors).
If one assumed 100% effective evacuation before plume passage, KI benefits would be reduced to zero (C/B = infinity). But such an evacuation is not realistically achievable for the following reasons:
a) release time is cae hour for RSUR-4, six hours for RSUR-1, and twelve hours for RSUR-2 (these three release categories are the only ones that produce significant Iodine releases) b)
majority of sequences include earthquake and/or LOSP c) roads could be damaged or blocked, communications disrupted, traffic signals inoperable, etc.
9
APPENDIX FACILITY-SPECIFIC COSTS FOR 0-5 MILE POPULATIONS The modified cost-benefit ratios defined in these responses have general applicability and are independent of the site-specific demographics that may characterize individual facilities.
Accordingly, facilities with 0-5 mile populations greater than those defined by the Reference Facility (10,700) will have greater costs but also correspondingly greater benefits. The following table provides site-specific population data and associated costs for KI under the stockpile and pre-distribution options.
Table A-1. KI Costs for the 0-5 Miles Population Populat.
KI Costs ($)
Reactor 0-5 miles Stockpile' Pre-dist.2 Browns Ferry 2,085
$208.50
$3,544.50 Brunswick 5,900
$590.00
$10,030.00 Cooper 930
$93.00
$1,581.00 Fermi 18,532
$1,853.20
$31,504.40 Fitzpatrick 6,352
$635.20
$10,798.40 Grand Gulf 2,165
$216.50
$3,680.50 Hatch 888
$88.80
$ 1,509.60 Hope Creek 1,325
$132.50
$2,252.50 LaSalle 1,332
$133.20
$2,264.40 Limerick 74,584
$7,458.40
$126,792.80 OC 25,805
$2,580.50
$43,868.50 Perry 12,923
$1,292.30
$21,969.10 Quad Cities 7,431
$743.10
$12,632.70 River Bend 3,099
$309.90
$5,268.30 Susquehanna 14,938
$1,493.80
$25,394.60 Vermont Yankee 8,330
$833.00
$14,161.00 WNP-2 484
$48.40
$822.80 Vogtle 384
$38.40
$652.80
)
Arkansas One 10,765
$1,076.50
$18,300.50 Beaver Valley 21,499
$2,149.90
$36,548.30 Callaway 843
$84.30
$1,433.10 Calvert Cliffs
- 7,739
$773.90
$13,156.30 Catawba 16,778
$1,677.80
$28,522.60 10 u
Populat.
KI Costs ($)
Reactor 0-5 miles Stockpile' Pre-dist.2 Crystal River 539
$53.90
$916.30 Davis Besse 2,002
$200.20
$3,403.40 Diablo Canyon 76
$7.60
$129.20 D C Cook 11,507
$1,150.70
$19,561.90 Ft Calhoun 12,720
$1,272,00
$21,624.00 Robinson 13,079
$ 1,307.90
$22,234.30 Farley 2,879
$287.90
$4,894.30 Haddam Neck 12,816
$1,281.60
$21,787.20 Indian Pt.
I10,372
$11,037.20
$187,632.40 Kewaunee 2,317
$231.70
$3,938.90 McGuire 5,128
$512.80
$8,717.60 Maine Yankee 5,111
$511.10
$8,688.70 N. Anna 1,925
$192.50
$3,272.50 Oconec 4,656
$465.60
$7,915.20 Palisades 5,784
$578.40
$9,832.80 Palo Verde 494
$49.40
$839.80 Pt. Beach 1,633
$163.30
$2,776.10 i
Prairie Is.
2,422
$242.20
$4,117.40 Rancho Seco 424
$42.40
$720.80 PSE&G 2,512
$251.20
$4,270.40 l
Shearon Harris 2,202
$220.20
$3,743.40 San Onofre 27,460
$2,746.00
$46,682.00 S. Texas 1,224
$122.40
$2,080.80 Sequoyah 13,938
$1,393.80
$23,694.60 St. Lucie 24,374
$2,437.40
$41,435.80 V C Summer 1,125
$112.50
$1,912.50 Surry 677
$67.70
$1,150.90 TMI 33,193
$3,319.30
$56,428.10 Trojan 9,456
$945.60
$16,075.20 Turkey Pt.
0
$0.00
$0.00 Yankee Rowe 1,618
$161.80
$2,750.60 Zion 39,243
$3,924.30
$66,713.10 TOTALS 598,017
$59,801.70
$1,016,628.90 11
Table A-1. KI Costs for the 0-5 Mile Population (Continued) i Stockpiling is based on a cost of $0.10 per person per year 2 Pre-distribution is based on a cost of $1.70 per person per year li 1
1 l
12 I
ENCLOSURE 2 RESPONSES TO COMMISSIONER ROGERS' 2/17/94 KI OVESTIONS 1
Describe the current status of the two survey studies that were to be performed for the FRPCC Potassium Iodide Subcommittee, i.e., from the States with NPP's and from the IAEA as well as the status of development of the FRPCC recommendation.
Potassium Iodide (KI) Surveys fjlPCC Surve_y i
FRPCC is currently conducting a national survey through the Conference of Radiation Control Program Directors (CRCPD) to determine the level of interest by individual States for a Federal stockpile of KI. To this end, on February 7, 1994, FRPCC forwarded to CRCPD a questionnaire for distribution to l
cognizant State agencies.
The survey solicits input from cognizant State agencies on whether the State favors a Federal stockpile of KI, and requests comments on three options: (I)
One central stockpile location for the entire country; (2) five to ten regional stockpile locations; (3) a stockpile in each State. The survey also seeks input from each State on method of distribution.
FRPCC expects to have the results of this survey by March 30, 1994. The FRPCC i
Subcommittee on XI is expected to analyze the result of the survey, and on j
that basis, identify options available for FRPCC final decision. Based on a very preliminary review of the responses received so far from the States, it appears that some States favor a Federal stockpile and some don't (Of course, i
adoption of a new Federal policy encouraging KI stockpiling might affect States' views of the desirability of KI.)
FRPCC Subcommittee on KI originally considered conducting a survey through IAEA. Later the Subcommittee decided not to pursue the IAEA survey.
When the subcommittee completes its analysis, it will present the results to i
the full committee.
Drqanization for Economic Cooperation and Development / Nuclear Eneroy Acency (0 ECD /NEA) Survey The Group of Experts on Nuclear Emergency Matters of the Committee for Radiation Protection and Public Health (CRPPH) is sponsoring a workshop on KI and other short term protective actions in June 1994. Sweden leads the task group in which the U.S. is a member. The task group assigned the NRC the task to develop a questionnaire for distribution by the NEA to member countries describing their policies on KI and other short term protective measures.
The results of this survey will be presented at the upcoming workshop in Europe.
Within NRC, AEOD is the lead on the interactions with other members of the Group of Experts nn Nuclear Emergency Matters.
ENCLOSURE 3 RESPONSES TO COMMISSIONER de PLANOVE'S 2/8/94 KI OVESTIONS 1.
What is the likelihood of an accident scenario in which one would not protect against other radioisotopes (i.e., no sheltering or evacuation recommended) but would still wish to apply KI to protect against
(
radioactive iodine?
Repl.y:
The staff is not aware of any accident scenario in which one would not protect against other radioisotopes but would still wish to apply XI for l
protection of the thyroid.
Radiciodine is produced within the nuclear fuel elements as one of many fission products.
Release of radiciodine to the environment can happen only after damage to the fuel elements has occurred.
If damage to the fuel elements is extensive enough to cause a significant release of radioiodine, that damage would also cause a significant release of other radioactive fission products, against which KI offers no protection. Therefore, one would always wish to protect the public by evacuation and/or sheltering from any event involving a significant release of radioiodine, because that release would also include other radioactive fission products.
However, KI could be useful for protection from the radiciodine component of the release in any accident scenario where the decision to recommend evacuation is delayed, or the actual evacuation is delayed due to physical impediments such as earthquake damage, loss of electric power for communications and traffic signals, weather (fog, hurricane conditions), etc.
For these scenarios, it is expected that sheltering would be recommended.
Similarly, KI could also be useful for protection from the radioiodine component of the release in " fast-breaking" scenarios with insufficient time for evacuation before plume passage.
KI would provide protection from exposure to radioiodine during the sheltering and evacuation phases of the accident.
2.
In order to evaluate the advantage of stockpiling KI near the plant vs.
I at a central location, it would be useful to know the probability of an
.l accident with short term release, say within less than 6-12 hours, vs. a
)
protracted release, e.g. several days.
Please provide relevant data.
,l Repl.y:
There have been no releases of radioiodine in the U.S. that would have warranted the use of KI if it had been available.
Thus, the response to this question is limited to the use of release predictions, not actual release data.
The significant radioiodine releases calculated for the Surry plant (in the analyses presented in NUREG-1150) fell within three categories, with the
following frequencies and predicted release times after start of the event (these same release categories were assumed in our analyses):
RSUR-4 1.6R-06/ reactor-yr 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> RSUR-1 2.9E-07/ reactor-yr 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> RSUR-2 2.4E-06/ reactor-yr 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> 3.
What are the cost / benefit ratios for the three options:
a) pre-distribution to residents within 5 miles of the plant (assuming the need for replacement, distribution to newcomers, loss of KI when needed, etc.)
b) stockpiling near each nuclear plant c) stockpiling at one location in the US for the scenario not requiring evacuation and most favorable to the successful use of KI.
Reolv:
Since issuance of SECY-93-318, in response to questions from Chairman Selin, the staff has estimated changes that would be needed in the cost / benefit ratios to account for:
pre-distribution vs. stockpiling; the potential for " double counting" certain benefits of KI at high doses; incomplete modeling in the MACCS code of health effects at high doses; more realistic efficiency of KI in preventing health effects when KI is administered after the start of plume passage; and lack of availability of KI to 100% of the population (these " correction" factors are discussed in the enclosed responses to the Chairman's questions (described on pages 6, 7, 8, and 9 of Enclosure 1].
Based upon application of these factors, the requested i
C/8 ratios are, respectively:
1 a) C/B - 69 b) C/B = 11 c)
Based on the population data given in Appendix A to Enclosure 2, the ratio of the maximum population within 5 miles of any nuclear plant (Indian Point) to the total population within 5 miles of all nuclear plants is:
110,372 / 598,017 - 0.185 - 18.5%
Assuming a single national stockpile would be 18.5% the size and cost of the total of all stockpiles for all plants, and assuming that the benefits of such a single national stockpile would be only 50% as great as they would be for local stockpiles, due to delays in getting the KI to the exposed population from one central location (further from the average plant than a local 2
~_
stockpile would be), the C/B ratio given in part b), corrected to apply to this situation, would be:
C/B = [11 x 0.185] / 0.5 - 4 The reduction in benefits by a factor of 0.5 is an assumption (i.e., the exact number has not been, and probably could not be, calculated without broad uncertainty). However, if a different benefit reduction factor is preferred, it can be substituted in the above equation for the "0.5", and the new result calculated.
For example, if one assumes that the benefits are only 25% as great as the local stockpile option, the resulting C/B ratio is:
C/B - [11 x 0.185] / 0.25 - 8.
4.
What are the downsides (side effects) of administering KI, alluded to on Pg. 1 of the NUMARC letter?
Repl y:
The reference to side effects was in the " Discussion" portion of a Federal Register Notice by the Food and Drug Administration (FDA) announcing its conclusion that KI was safe and effective for use in a radiation emergency.
In tha; Notice, the FDA stated:
"The final recommendations noted that uncertainties still exist about its use and sioc effects".
Side effer.ts of KI use can include:
Intrathyroidal effects are iodint-induced thyrotoxicosis (hyperthyroidism), and iodine-induced hypothyroidism.
Extrathyroidal effects are erythema nodosium, ioderma, urticaria, bullous eruptions, acne, dermitis herpetiformis, swelling of salivary glands, rhinitis, iodism, vasculitis, serum sickness, and anaphylactoid reactions.
Staff conclusions regarding the frequency and seriousness of such side effects are:
"The most current data suggest dose of 130 mg of KI at 1 x 10'pn adverse reaction rate to a daily oral or less", and "Among the few adverse reactions that have been reported, the reactions are agl life-threatening.
In most cases, the reactions are self-limiting or quickly abate with discontinued medication."
The attachment contains a discussion of the above-listed side effects and the bases for the above conclusions (which were accepted by the staff and which are quoted from our contractor's report, An Analysi_s of KI Prochvlaxis for the General Public in the Event of a Nuclear Accident, S. Cohen & Associates, 3
April, 1992, Section 2.6, " Potential Adverse Reactions to Stable Iodine",
pages 2-20 through 2-25 (provided as an attachment to this enclosure).
However, in the only case in which XI was used on a massive scale -- after Chernobyl -- the Poles reported negligible side effects among the 19 million recipients of KI.
This was reported in an article entitled "Inside Prophylaxis in Poland After the Chernobyl Reactor Accident: Benefits and Risks" in the May 1993 issue of The American Journal of Medicine.
5.
Is the $1.70 per person (per year?) cost for distribution estimated by staff, the cost of pre-distribution or the cost of distribution of stockpiled KI at the time of the accident? How did staff arrive at this figure?
Reply:
The $1.70 per person per year is the cost of pre-distribution.
The costs are based on the experience of the state of Tennessee in which State officials purchased and pre-distributed 3704 vials, each containing KI tablets for an entire household.
Costs included a public relations program which attempted to establish public confidence by presenting information regarding the objectives of iodide prophylaxis, safe storage, proper usage, dosage, contraindications, etc. The total cost of the program was $125,000. Assuming a five year KI shelf life and four individuals per household, cost per person per year is:
$/ person-yr = $125,000 / [(3704 x 4) x (5)] - ~$1.70 6.
In developing the cost / benefit ratios, what assumptions are made concerning cost per averted death or cost per averted thyroid problem?-
Reolv:
Costs per averted thyroid problem used in deriving the cost / benefit ratios are:
Excluding Including Thyroid Health Psychological Costs Psychological Costs Effect (Thousands)
(Thousands)
Adult Fetal Adult Fetal Nodule
$43
$70
$543
$570 Non-Fatal 59 80 559 580 Cancer Fatal Cancer 661 32 1,161 532 Hypothyroid.
44 90 544 590 Chapter 5 and Appendix 0 of the Draft Report (An Analysis of KI Pro _ohylaxis for the General Public in the Event of a Nuclear Accident, S. Cohen &
Associates, April, 1992) contain a complete discussion of these costs.
4
I l
7.
Which of the three options in Question 3 are used by the countries that presently intend to use KI?
1 Reply:
The Office of International Programs has requested information on potassium iodide from a number of countries. To date, information has been received from Sweden, Switzerland and the United Kingdom.. Responses from additional countries will be provided to the Commission when they are received.
Sweden:
The federal government has distributed potassium iodide pills to the inhabitants in the Emergency Planning Zone (between 12 and 15 km) of each of the four reactor sites in Sweden.
In addition they have stockpiles of pills at each reactor site and at a central repository.
1 The government is actively reviewing their policy in this regard and are considering additional pre-distribution.
Some local governments have requested distribution of the pills because of their proximity to foreign reactors, such as Ignalina.
Switzerland:
In Switzerland, potassium iodidz pills are both pre-distributed and stockpiled near reactor sites. The pills are pre-distributed to the local population in Zone 1 (immediate area around the power plant) of the emergency plan.
In addition, pills are stockpiled for distribution subsequent to an accident for Zone 2 (community to approximately 20 km.).
As a result the pills are widely available. The potassium iodide program was a joint effort of the federal and local governments and the utilities.
United Kinadom Generally, potassium iodide pills are not pre-distributed to the public in advance.
However, the national guidelines for the use of potassium iodide do permit pre-distribution to isolated households or communities.
The pills are stockpiled in the local community near nuclear facilities. The stockpiling is the responsibility of the plant operator, although the local health authorities are responsible for having supplies at evacuation centers.
The actual distribution method is left to the discretion of the-local authorities and is specified in the emergency plan. The actual methods do differ among communities.
5
[;.
8.
What is recommended /done by IAEA, France, and Japan?
Reply:
1hla The IAEA has no policy or position on the use of KI. The IAEA referred the NRC to the World Health Organization (WHO).
World Health Oraanization The Office of International Programs has requested, but not yet received, information from WHO on its current policy or position with regard to the use of KI.
It should be noted that in 1991, WHO report EUR/ICF/CEH 102(s) 77118 recommended stockpiling of KI, and said that: " Stocks of iodine should be stored strategically at plants including hospitals, schools, and fire and police stations."
France:
French safety policy is to use potassium iodide is a countermeasure in case of accidents at nuclear facilities. Generally, the pills are in ample supply and widely distributed throughout the country.
The pills are stockpiled at major nuclear facilities and at a central repository. The pills are not distributed to the public in advance. The decision to distribute the pills is made by the operating organization for its personnel and by the local government authorities for the public.
Actual distribution is a local undertaking.
i Jaorn i
l Potassium iodide pills are stockpiled in the vicinity of nuclear power plants but they are not pre-distributed to the public. The pills are stockpiled at health centers and emergency facilities in the local communities. The national government does not maintain a central stockpile.
The use and distribution of the pills are handled by the local government in accordance with the facility emergency plan.
Although the stockpiling and use of the pills are local government functions, the federal government provides
)
financial support for these activities.
)
l 9.
Given a brief release of iodine-(e.g., < 6 hrs), how does the effectiveness of administering KI change as a function of time of administration relative to the time of release?
Repl y:
. There is a complex temporal relationship between time of potassium iodide (KI) administration and exposure to radioiodine from a passing plume.
KI prophylaxis or thyroid blockade is primarily achieved by introducing stable iodide into the circulating blood in sufficient quantity that " saturates" the thyroid's iodide transport mechanism, which prevents subsequent uptake of
-(stable or radioactive) iodide from the circulating blood.
The KI dose-response curve for inducing thyroid blockade reaches near maximal levels of thyroid blockade (i.e., 95%) for doses of about 30 mg and asymptotically
~
reaches a maximum level of 99% for doses greater than 50 mg.
Critical to 6
l j
~
4 thyroid protection is that the KI level in the circulating blood is maintained at levels greater than 30 mg in order to maximally block the thyroidal uptake of radioiodide that may also be present in the circulating blood.
Both stable and radioactive iodide are continuously removed from the circulating blood with a half-period of about six hours. Thus, for a 130 mg dose of KI, serum levels of KI decline from 130 mg to about 30 mg over a period of 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />, and exposure to radioiodine from a passing plume within this time frame of 0 to 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> post-KI administration is reduced with near maximal efficiency of 99%.
When exposure to radiciodine precedes KI administration, the prophylactic impact of KI is limited to the fraction of radioiodine that has not been removed from the circulating blood.
For example, if an individual were exposed to a slua exposure of radiciodine at time zero, about one-half of the ingested radiciodine will still be in the circulating blood six hours after intake. KI administered fully six hours after such a " point-in-time" exposure would block the remaining 50% of blood-born fraction with a 99% efficiency.
Unlike a slug exposure, plume exposures are likely to have durations of hours.
For plume exposures, the efficacy of thyroid protection, when radiciodine exposure precedes KI administration, may be a combination of the above-cited conditions.
For example, if KI is administered two hours after plume arrival and plume duration is six hours, thyroid protection is based on thyroid exposure / blockade that (1) precedes KI administration and (2) follows XI administration.
The overall thyroid protection in this case is the time-weighted sum of protection for pre-and post-KI administration.
For the above-stated condition, it is calculated that the KI administration two hours after plume arrival (having a duration of six hours) can reduce thyroid exposure by about 92%.
10.
When stockpiled KI exceeds its shelf life, does it present a waste disposal problem; if so, please discuss the issue (see pg. 6 of NUMARC letter)?
Reply:
Both potassium and iodine in elemental or ionic form are ubiquitous in the environment.
Due to its solubility, iodide is readily leached from soil by rain, which ultimately carries it to the world's oceans.
From ocean waters, iodide evaporates and follows water vapor that constitutes rain clouds which replenish the soil and complete the cycle.
Iodide (as well as potassium) is essential to good health for humans and animals, and the main source is through food.
The highest natural iodide content is found in sea foods, which may reach concentrations as high as 800 pg per kg.
Iodide is also contained in a variety of food supplements (e.g., iodized table salt, vitamins, kelp tablets) and may be administered for pharmacological reasons (e.g., as in cough syrup or expectorant).
From the above discussion, it is not expected that KI would pose significant problems for disposal.
Furthermore, informal communications with several commercial waste management / disposal services identified landfills designed for chemical wastes as defined by current RCRA regulations as the most cost-effective type of disposal site.
Disposal costs (inclusive of shipping) involving 55-gallon 7
A 4 4
(:
l drum containers are estimated at $200 per drum container. Assuming the total of all KI stockpiles for all persons living within five miles of any nuclear plant consists of 10 tablets o 130 mg FI for each of one million individuals, the total quantity of 1.3 x 10[ g or 1300 kc is roughly the equivalent of two to three 55-gallon drum containers that wou~ d require disposal at five-year intervals. Thus, the annualized disposal cost is estimated at $100 per year.
ANBEX, one of two vendors licensed by the FDA, has stated bwfilingness to assume responsibility for the disposal / disposal costs. associated with KI.
An alternative to the disposal of KI (assuming that disposal is even necessary
- see response to Question #12) is the potential 'for recycling KI for alternative uses.
Potential alternative uses for " recycled" KI include its use in photographic emulsions, analytical laboratories, animal. feeds, etc.
11.
HowdoyourelatAthe-Tennesseeexparience(Ref.7toSECY-93-318 1
" Summary ofl Assumptions Made by and Results of the Potassium Iodide Stockpiling Cost-Benefit Ratio Ruanalysis") in the pre-distribution program to'the potential effectiveness of any proposed pre-distribution program (relates to cost / benefit ratio calculated for question no. 3, scenario (a))?
Realy:
The Tennessea experience prcvided the bases for all of our assumptions in the analyses of the predistribution option, both regarding cost (see response to Question 5) and regarding effectiveness.
It was assumed that 70% of the population has access to preaistributed KI, and it was assumed that i
all individuals who have access to their predistributed KI take it before plume arrival, so that the achieved overall dose reduction factor, among that i
70% of the population, is 99%.
These assumptions are also used in the enclose! responses to the Chairman's'
)
questions (page 9, Enclosure 1).
s 12.
Does staff agree with the estimated shelf life (3 years) of KI in Ref. 7 to SECY-93-318 (" Summary of Assumptions Made by and Results of the Potassium Iodide Stockpiling Cost-Benefit Ratio Reanalysis")?
\\
Early:
No, the currently accepted shelf life is 5 years, which was assumed in all of our analyses.
Carter-Wallace, one of two FDA-approved suppliers of KI tablets, has periodically tested KI for residual pharmacological potency.
Based on test data supplied by Carter-Wallace Laboratory, the FDA's Metabolism Division has verified a minimm shelf-life of 5 years for KI tablets supplied in vials (Carter Wallace) or in blister packs (ANBEX) (informal communication, Feb. 24, 1994, with Solomon Sobel, M.D., Division of Metabolism (301-443-3490).
At this time, however, it is uncertain why, under proper storage conditions, this stable metal-salt would not be expected to have.a shelf-life that extends to decades and would, therefore, never require disposal for the operating life of nuclear power plants.
8
O ATTACHMENT (to Enclosure 3)
I 2.6 Potential Adverse Reactions to Stable Iodide I
Iodine is a ubiquitous but variable constituent in the emironment. Due to its solubility, edide is readily leached out of soil by rain which ultimately carries it to the world's owans. Fmm ocean waters, iodide evaporates to the atmosphere where it is concentrated in rain which replenishes the soil (Koutras 1980). Iodide is essential to good health, and the main source for humans is thmugh food. The highest natural iodine content is found in sea foods which may reach concentrations as high as 800 pg iodine per kg.
2-20
Other dietary sources ofiodide are eggs, meat, milk, and cereals. Additionally, many foods are artificially enhanced in the United States. by additives such as iodized salt. It is estimated that the daily intake ofiodide for adults in the United States ranges between 125 pg to 700 pg (Oddie 1970; Rubery 1988).
Dietary iodide levelu play a key role in potential adverse reaction incidence rates.
'1 When dietary levels are high, adverse reactions are assumed to be at their lowest rate.
Epidemiological and metabolic studies support a minimum daily adult requirement of 100 pg; endemic goiter is usually not found when the dietary intake ofiodine is above 100 pg per day (Stanbury 1980). However, the American Thyroid Association (ATA) has stated that-
"... [while] many anecdotal reports ofisolated reactions to iodides have been published, reliable incidence data do not exist. It is reasonable to assume that obvious iodide reactions are rare in the United States where the diet is high in iodine content... When reactions do occur, they may be intrathyroidal or extrathymidal"(Becker 1984)
In instances of dietary deficiency, the synthesis of thyroid hormones is restricted and the serum concentration of T is low. This stimulates the thyroid pituitary feedback 4
mechanism with increased synthesis and secretion of TSH. Elevated serum levels of TSH increase thyroid metabolism ofiodide as well as the growth of the thyroid which under pmlonged conditions ofiodide deficiency becomes goitrous.
Stable iodide prophylaxis is based on the prompt administration of relatively large amounts of stable potassium iodide (i.e.,130 mg per day) over a period of a few days to a 1
potentially exposed population. This transient increased intake of iodide may produce detrimental changes in iodide metabolism, thyroid function, and immune reactions among subjects with low dietary iodide intakes. Also at risk for adverse reactions are individuals with existing thyroid disorders and pathologies. Lastly, the fetal thyroid is potentially at risk from pharmacological levels of iodide. Table 2-2 identifies the most common adverse reactions known to be associated with iodide.
Adverse reactions to iodide may be categorized as intrathyroidal and extrathyroidal.
1 2-21
[.
Table 2-2 Adverse Reactions to Iodide Intrathyroidal Effects - Excess or insufficient production of thyroid hormones.
Iodide-induced thyrotoxicosis (hyperthyroidism)
Iodide-induced hypothyroidism e
Extrathyroidal Effects - non-thyroid related reactions and hypersensitivity reactions.
Erythema nodosium; ioderma; urticaria; bullous emptions; e
acne; dermitis herpetiformis; etc.
Swelling of salivary glands, rhinitis, iodism Vasculitis; serum sickness; anaphylactoid reactions o
2.6.1 Intrathyroidal Adverse Reactions individuals with normal thyroid function are aql at risk for intrathyroidal effects leading to conditions of hyperthymidism (thyptoxicosis) and. hypothyroidism.
Hyperthyroidism, when induced by exogenous administration of lodide, is termed "Jod-Basedow" phenomenon and involves an overproduction of thyroid hormone.
This phenomenon is common to individuals whose thyroid is no longer under the regulatory contml of the pituitary gland's secretion of TSH.
The underlying pathologies for autonomously functioning thyroids were previously discussed and include thyroid nodules / cancer, and Graves Disease (Alexander 1%5; Vagenakis 1972; Tunbridge'1977).
Iodine supplementation has also been recognized to increase the incidence of hyperthymidism among individuals in previously iodine-deficient areas following the intmduction ofiodized salt. This Jod-Basedow phenomenon in previously lodide-deficient areas is thought also to involve individuals with autonomously functioning thyroids.
Apparently, the thyroid in these individuals was functioning autonomously at a hyperactive level before supplemental administration of iodide, but was unable to manifest hyperthyroidism owing to the limitation of hormone synthesis imposed by the low dietary intake (Connolly 1970; Fradkin 1983).
2-22 I
l For select individuals, the administration of iodide may have the reverse effect of induced hypothyroidism. The antithyroid action of acute iodide overload resulting in a state of hypothyroidism is well documented (Wolff 1%9; Nagataki 1974). In normal subjects, an iodide overload causes a transient block of iodide organification (i.e., thyroid hormone synthesis) known as the "Wolff-Chaikoff effect"(Wolff 1980; 1%9). Even with continued administration and elevated serum levels of iodide, healthy subjects escape from this transient and subclinical hypothyroid state within hours and resume normal thyroid hormone production. In some individuals, the induction of the Wolff-Chaikoff effect by exogenous iodide is not followed by a prompt escape of its inhibitory effect ofiodide organification, so that a state of prolonged hypothyroidism and possible goiter develops. Continuing and unrelieved Wolff-Chaikoff thyroid suppression is seen among individuals with Hashimoto's thyroiditis, Graves' Disease, and after surgical thyroidectomy or I-131 treatments (Wolff 1%9; Braverman 1971).
Sub-Populations Likely to Manifest Intrathyroidal Effects from KI Prophylaxis. It is well established that Hashimoto's thyroiditis, Grave ' Disease, and idiopathic myxedema are organ-specific autoimmune disorders of the thyroid. These and other autoimmune disorders 1
probably develop because of the consequences of an abnormal function or reaction of the immune system that is genetically predisposed. The concept that excess iodine might indirectly influence thyroid function by triggering thyroid autoimmune reactions is based on clinical studies that suggest an association between increased consumption of dietary iodine and autoimmune thyroid disorders. Studies have shown a greatly reduced incidence rate of.
lymphocytic infiltration of thyroid tissue, Hashimoto's thyroiditis, and Graves' Disease in iodine-deficient and goiter-endemic areas when compared to areas of iodine sufficiency (Bouki 1983; Hall 1996; McGregor 1985). Although the precise mechanismo responsible for the initiation of autoimmune phenomena against the thyroid gland in genetically predisposed individuals are highly speculative, there is evidence that iodine can play a role in the initiation and expression of these autoimmune thyroid disorders.
The quantity of exogenous iodide capable ofinducing thyroid suppression is not easily defined since it will depend on external factors, such as dietary intak'e ofiodide, and the inter relationship ofinternal factors such as the intra-glandular pool ofiodide, the efficiency of the autoregulatory mechanism which ptotects against thyroid overloading, and the underlying thyroid disorder. The American Thyroid Association estimates that daily doses of between 50 to 500 mg of iodide may induce prolonged hypothyroidism among these predisposed individuals (Becker 1984).
A second susceptible target population which may be regarded as normal / healthy includes fetuses in the second and third trimester. The partially developed feta' thyroid i
during this time has the ability to concentrate iodide, but does not yet possess the autoregulatory mechanism needed to escape the Wolff-Chaikoff effect (Delange 1985; Sherwin 1982).
2-23
r t
C Chronic consumption of iodide-containing medications such as cough medicine and antiasthmatic drugs has been shown to induce fetal hypothyroidism and fetal goiter (Walfish 1983; Mehta 1983). Fetal and neonatal iodine overload has also been observed following the use of iodinated x-ray contrast media during pregnancy (Rodesh 1976) and the cutaneous application ofiodinated skin disinfectants (Povidone-iodine) at time of delivery (Chanoine 1986). The concentrations of maternal iodide required to induce a fetal Wolff-Chaikoff effect have not been properly quantified but are thought to be relatively high (Delange 1988).
2.6.2 Extrathyroidal Adverse Reactions Numerous non-thyroidal effects have been linked to phamiacological use ofiodide.
t Persons potentially at risk for non-thyroidal adverse reactions are individuals with a known sensitivity to iodide. A particularly sensitive target population comprises individuals with hypocomplementemic vasculitis (Curd 1979). The most common reactions involve swelling of the salivary glands (sialademitis or iodide mumps), a host of skin reactions (erythema nodosum, ioderma with necrotic skin lesions, urticaria, bullous eruptions, acne-form skin eruptions, etc.), iodide fever, rhinitis, and iodism (Becker 1987; Robery 1988; Yalow 1983).
These reactions are generally observed with large doses ofiodide, are self-limiting, and are readily reversed by cessation of drug use. Rare, but of greater significance, are certain hypersensitive or allergic reactions which produce symptoms such as fever, pains in joints, edema of the face and glottis, angiitis, vasculitis, and anaphylactoid /anaphylaxis reactions.
2.6.3 Adverse Reaction Incidence Rate Potential adverse reactions to iodide when taken orally in daily doses of 130 mg can j
be assumed to be very few for the general United States population. This assumption is based on the extrapolation of data reported to the Food and Drug Administration (FDA).
The FDA's Division of Epidemiology and Smveillance maintains a computerized data base of adverse drug reactions known as the Adverse Reaction Reporting System (ARRS).
The primary purpose of the ARRS is to serve as an early warning system for adverse reactions to drugs subject to FDA regulations. Approximately 90% of adverse reaction reports received by the FDA are submitted by drug manufacturers who by law must report all adverse events that become known to them. The remaining 10% of reports are submitted directly by health cr.r professionals in response to suspected adverse reactions among their patients.
An estimate of the potential adverse reaction incidence rate to iodide is best derived from data involving cough syrups and expectorants. Potassium iodide is a major ingredient in these oral medications and results in average daily doses of several hundred milligrams of Kl. Among the few adverse reactions that have been reported, the reactions are aqt life-threatening. In most instances, the reactions are self-limiting or quickly abate with discontinued medication.
2-24
~
A second major class of pharmaceuticals for widch adverse reactions have been reported is iodinated x-ray contrast media. The high attenuation of diagnostic x-rays by organified iodine is the basis for its use in routine medical procedures.
- However, exptrapolation of an adverse reaction incidence rate from iodinated contrast data is subject to numerous uncertainties.
l Appendix C of this report contains summary data of adverse reactions to iodide
{
which have been reported to the FDA.
Also included are basic assumptions and quantitative methods used to derive a best estimate of the adverse reaction incidence rate.
The most current data suggest an adverse reaction incidence rate to a daily oral dose of 130 mg of KI at 1 x 10' or less.
2-25
-