ML19275A450

Reg Guide 8.20,Revision 1, Applications of Bioassay for I-125 & I-131

ML19275A450
Person / Time
Issue date:	09/30/1979
From:	NRC OFFICE OF STANDARDS DEVELOPMENT
To:
References
AB35-1, REGGD-08.020, REGGD-8.020, NUDOCS 7910040426
Download: ML19275A450 (6)

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Revision 1 U.S. NUCLEAR REGULATORY COMMISSION September 1979

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OFFICE OF STANDARDS DEVELOPMENT 1MS 327 REGULATORY GUIDE 8.20 APPLICATIONS OF BIOASSAY FOR l-125 AND l-131 l, O. -.-

.f A. INTRODUCTION vitro of materials excreted or removed from the body.

Section 20.108, " Orders Requiring Furnish-l ing of Bioassay Services," of 10 CFR Part 20 Intake-The total quantity of radioactive i

" Standards for Protection Against Radiation,'-

material entering the body.

indicates that the Nuclear Regulatory Commis-4 sion (NRC) may incorporate into a license pro-In vivo measurements-Measurement of gamma-visions requiring a specific program of or x-radiation emitted from d ase material i

bioassay measurements as necessary or located within the body for the purpose of desirable to aid in determining the extent of an detecting or estimating the quantity of radio-individual's exposure to concentrations of active material present.

radioactive muerial. In certain cases, the requirement on bioassay may also be included in In vitra measurements-Measureme.it of radio-the license by reference to procedures specify-activity in samples af material excreted from ing in vivo measurements, measurements of the human body.

l radioactive material in excreta, or both.

This guide provides criteria acceptable to the NRC staff for the development and implementa-

1. Conditions Under Which 13ioassay Is Necessary tion of a bioassay program for any licensee bioassay is necessary when an '*

handling or processing I-125 or I-131.

It

a. Routinet further provides guidance to such licensees individual handles in open fonn unsealed 2 i

regarding the selection of workers who should quantities of radioactive iodine that exceed participate in a program to detect and measure those shown in Table 1 of this guide. The possible internal radiation exposure. The guide quantities shown in Table 1 apply to both the is programmatic in nature and does not deal quantity handled at any one time or integrated

n with measurement techniques and procedures.

as the total amount of activity introduced into a process by an employee over any 3-month B. DISCUSSION period.

The topics treated in this guide include de-

b. When quantities handled in unsealed terminations of (1) whether bioassay should be form are greater than 10% of Table 1 values, performed, (2) frequencies of bioassay, (3) a who should participate, (4) the actions to take

%nes indicate substantive changes from previous issue.

I based on bioassay resulfs, and (5) the partic-1Routme means he re that an individual is assigned on a ular results that should initiate such actions.

scheduled and repeatable basis to submit specimens for bionssay or to report for m vivo measurements. Either radiochemical l

For the user's convenience, the following bi assay f urm or in = coun*ing is acceptable to the NRC staff for estimatmg internal radacectivity burdens or intakes.

3 termr. are presented with their definitions as la some cases, however, a licensee may wish to corroborate used in this guide:

est2 mates fmm urmalysis data with m vivo deternanations.

Smce there are adequate references m the literature to help devise bioassay measurements. this guide does not include Bioassay-The determination of the kin d,

recommended analytical procedures. Each installation should j

quantity or concentration, and location of adopt procedures or cbtain services best suited to its own

"d'~

radioactive material in the human body by direct (in vivo) measurement or by analysis in rsee discussen in the footnote to Table 1 of this ruide.

i i

USNRC REGULATORY GUIDES Comments should be sent to the Secretary of the Commission. U.S.

Nuclear Regulatory Commission. Washington, D.C. 20555, Atten-Re atory Guides are issued to describe and make available to the tion: Docketmg and Service Branch pu ic methods acceptable to the N RC staff of implementing specific parts of the Commission's regulations, to delineate techniques used The guides are ass med in the following ten broad divisions:

by the staff in evaluating specific problems or postulated accidents >r to provide guidance to applicants. Regulatory Guides are not substi-

1. Power Reactors

6. Products tutes for regulations, and compliance with them is not required.

2. Researth and Test Reactors

7. Transportarion Methods and solutions different from those set out in the guides will

3. Fuels and Materials Facilities

8. Occupational Health be acceptable if they provide a basis for the findmgs requisite to the

4. Environmental and Siting

9. Antitrust and Finandal keview issuance or continuance of a permit or license by the Commission.

5. Materials and Plant Protection 10. General Copies of issued guides may be purchased at thecurrent Governmint Comments and suggestions for improvements in these guides are Printing Office, price. A subscription service for future guides in sye-encouraged at all times, and guides will be revised. as appropriate,to cific divisions is available through the Government Prmting Office.

accommodate commenta and to reflect new information or experi-Information on the subscription service and current GPO prices mty ence. This guide was revised as a result of substantive comments be obtained writing the U.S. Nuclear Regulatory Commissiori, received from the public and additional staff review.

Washington,

.C. 20555, Attention: Publications Sales Managir.

Y910040y,%

e routine bioassay may still be necessary under

3. Ty pes of liioaway s That Should lie Perfonned certain circumstances. A written justification for not performing such measurements should

a. Baseline fpreemployment or preopera-be prepared and recorded for subsequent re-tion al). Prior to beginning work with ra dio-view during NRC inspections whenever bio-active iodine in sufficient quantity that bio-assay is not performed and the quantities assay is specified in regulatory position 1.

handled exceed 10* of the levels in Table 1.

b.

Rou tin e. At the frequency specified in

c. Except as stated in regulatory posi-regulatory position 4 tion 1.e, bioassay is not required when pro-cess quantities handled by a worker are less

c. Emergency. As soon as possible after any than 10% of those in Table 1.

incident that might cause thyroid uptakes to exceed burdens given in regulatory posi-

d. In nuclear reactor installations, employ-tion 5.a(2), so that actions recommended in ees should be bioassayed by an in vivo count regulatory position 5.a(2)(b) can be most effective <

within 30 days after the end of exposure in

$ work locations where concentrations exceeded, Postoperational and with Separation Ph,vs-d.

or might have exceeded, 9 x 10

pCi/ml averaged over any 40-hour period. Table 1 and ical. A bioassay should be performed within 2 regulatory position < regarding frequency of weeks of the last possible exposure to 1-125 or I-131 when operations are being discontinued bioassays are not applicable to reactor licen sees.

r when the worker is terminating activities with potential exposure to these radionuclides.

c. Special bioassay measurements should Diagnostic. Followup bioassay should be e.

be performed to verify the effectiveness of performed within 2 weeks of any measurements respiratory protection devices and protective exceeding levels given as action points in clothing. If an individual wearing a respiratory regulatory position 5 in order to confirm the protective device or protective clothing is sub-initial results and, in the case of a single jected to a concentration of I-125 or I-131 (in intake, to allow an estimate of the effective any form) in air such that his or her intake half-life of radiciodine in the thyroid.

with no protection would have exceeded the 2

limits specified in paragraph 20.103(a)(1) of 4. 17requency 10 CFR Part 20,3 bioassa3 s should be per-formed to detc.mine the resulting actual 1-125 a.

Initial Routine. Except in situations +

or I-131 intake. These special bioassay proce-where thyrcid burdens may exceed quantities dures should also be conducted for personnel specified in regulatory position 5.a(2), a bio-wearing respirators if for any reason the I-125 assay sample or measurement should be or I-131 concentration in air and the duration obtained within 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> following entry of an

' of exposure are unknown or cannot be conser-individual into an area where bioassay is I

vatively estimated by calculation.

performed in accordance with regulatory posi-tions 1 and 2 (but waiting at least 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> for distribution of a major part of the iodine to the thyroid * ) and every 2 weeks or more

2. Participatum frequently thereafter as long as the conditions described in regulatory positions I and 2.

All workers handling radioactive iodine or sufficiently close to the process so that intakt When work with radioactive iodine is on!

exist.

an infrequent basis (less frequently than every is possible (e.g., within a few meters and in 2 weeks), bioassay should be perfonned within the same room as the worker handling the 10 days of the end of the work period during material) should participate in bioassay pro-which radioactive iodine was handled (but notl grams described in regulatory position 1.

sooner than 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> unless emergency actions to obtain an ea rly progaosis and thyroid

%1tiplyin g the concen tra twns gwen m A gendix D to 10 cFR rart 00 Table !. column 1, 5 x 104 pCo m1 for t-125

b. After 3 Months. When a periodic meas-( soNble) and 3 x 10-* pCimi for 1-131 (soluble), by 6.3 x 108 ml gwes the corresponding quarterly mtake of the respect 2ve u remen t frequency-has been selected in iodmes by mha at:on These quarterly mtakes woulJ be about accordance with regulatory position 4.a it may u pCi f ar 1-125 and 5.7 uct fcr t-131. which would give a thyroid dose commit nent of aboct 7 5 rems ta a 20-gram thyroid be changed to quarterly if, after 3 months, all mtegrated over an future time usmg effective ha:f-hves cf 41.8 the following conditions are met:

days for !-125 an6 7 6 days for 1-131 and usmg a quality factor (QF) of 1 7 to cal.%.1 ate effective dismtegration erergy m the (1) The average thyroid burden for case of I-125 (This QF of 1.7 ts used for conservatism. even each individual working in a given area was though the International Ccmmaswn en Ralmlegical Protectwn (1963) and the Natwnal Council on Radiation Protectwn (1971) have publ2shed a QF cf 1. because scme calculations in more

'NCRP Report No. 55 " Protection of the Thyroid Gland m recent scient.fic liternure hava suggested the use of QF values the Event of Releases of Radwiodme. " National Council en higher then 1 for e:ectren or beta energies of 0.03 MeV or Radiation Protectwn and Meas u remen ts. Wa shm gton. D C.

less.)

Aug;2st 1.1977

p. 21.

109~9 P'B s

8. E-2

a less than 0.12 pCi of I-125, less than 0.04 pCi S 20.103 of 10 CFIt Part 20 to be exceeded, the of I-131, and less than the corresponding pro-licensee should restrict the worker from 5 of a mixture of these further exposure until the source of exposure portionate amount nuclides during the initial 3-month period; is discovered and corrected.

(c) Corrective actions that will elim-(2) The quarterly average radioiodine inate or lower the potential for further expo-concentration (pri/ml) in air breathed by any sures should be implemented.

worker (as obtained when measurements of radioiodine concentrations in air are required) does not exceed 25't of the concentration values (d) A repeat bioassay should be taken within 2 weeks of the previous measure-for " soluble"(s) iodine given in Appendix B to ment and should be evaluated within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> 10 CFR Part 20, Table I, Column 1, (5 x 10-9 pCi/mi for I-125 and 9 x 10-9 pCi/ml for 1-131),

after measurement in order to confirm the i.e., 251, of these concentrations multiplied by presence of internal radiciodine and to obtain the total air breathed by an employee at work an estimate of its effective half-life for use in 8 ml,

estimating dose commitment.

during one calendar quarter, 6.3 x 10 does not exceed 0.8 pCi of I-125 or 1.4 pCi of (e) Reports or notification must be 5

I-131. The appropriate proportionate amount of a mixture of these nuclides should be used provided as required by SS 20.405, 20.408, and 20.409 of 10 CFR Part 20 or as required as a guide when both I-125 and I-131 are by conditions of the license pursuant to present; and S 20.108 of 10 CFR Part 20.

(3) The working conditions during the (2) If the thyroid burden at any time 3-month period with respect to the potential for exceeds 0.5 pCi of I-125 or 0.14 pCi of I-131, exposure are representative of working condi-the following actions should be taken tions during the period in which the quarterly bioassay frequency will be employed, ind there (a) Carry out all steps described in is no reasonable expectation that the criteria in regulatory positions 4.b(1) and 4.b(2) above regulatory position 5.a(1).

will be exceedec.

(b) As soon as possible, refer the l case to appropriate medical consultation forl After Use _ of Respiratory Protection De-recommendations regarding therapeutic proce-l c.

l vices. Between 6 and 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> after respiratory dures that may be carried out to accelerate !

protective devices, suits, hoods, or gloves are removal of radioactive iodine from the body,

. used to limit exposure as stated in regulatory This should be done within 2-3 hours after

! position 1.e.

exposure when the time of exposure is known l

For individuals placed on a quarterly so that any prescribed thyroid blocking agent !

schedule, sampling s: ould be randomly distri-would be effeMive.4 buted over the quar.er but should be done i within ore week after a procedure involving (c) Carry out repeated measurements the handling of I-125 or 1-131. This will pro-at approximately 1-week intervals at least until the thyroid burden is less than 0.12 pCiof.-125 vide a more representative assessment of expo-or 0.04 pCi of I-131. If there is a possibility of

. sure conditions longer-term compartments containing I-125 or S. Action Points and Conesponding Actions 1-131 that require evaluation, continue meas-urements as long as necessary to ensure that

a. Biweekly or More Frequent Measurements appreciable exposures to these other compart-(1) Whenever the thyroid burden at the ments do not go undetected.

time of measurement excceds 0.12 pCi of I-125 or 0.04 pCi of I-131, the following actions b.

Quarterly Measurements. Carry out actions at levels as indicated under regulatory should be taken:

position 5.a(1) and (2). If measurements and surveys indicate an appreciable likelihood that (a) An investigation of the opera-a worker will receive further exposures tions involved, including air and other in-plant surveys, should be carried out to determine exceeding the criteria of regulatory posi-the causes of exposure and to evaluate th e tions 4.b(1) and 4.b(2), reinstitute biweekly or more frequent bioassays.

potential for further exposures.

(b)If the investigation indicates thr: further work in the area n.ight result in D. IMPLEMENTATION of a worker to concentrations that exposure would cause the limiting intakes estetished in The purpose of this section is to provide in-i"' Sea Appendix B to this guide for a descrgtwn and example formation to applicants and licensees regarding l of unng this conditwn for amures.

IO95 329 8.20-3

the NRC staff's plans for using this regulatory incorporated in their licenses in accordance guide.

with 9 20.108 of 10 CFR Part 20.

Except in those cases in which the applicant or licensee proposes an acceptable alternative if an applicant or licensee wishes to ue the method described in this regulatory guide on l

method, the staff will use the methods l described herein after December or before December 15, 1979, the pertinent 15, 1979, in portions of the applicatior or the licensee's evaluating the radiation protection pfwgrams of performance will be evaluated on the basis of licensees who have bioassay requirements this guide.

Table i ACTIVITY LEVELS ABOVE WillCII DIOASSAY FOR I 125 OR I 131 IS NECESSARY Actisityllandk

.n Unsealed Form Making Bioassay Necewary*

Volatile

!!ound to or Nomolatile Types of Operation Dispersible*

Agent

• Processes in open room or bench, with possible escape 1 mci 10 mci of iodine from process vessels Processes with possible escape of iodine carried out 10 mci 100 mci within a fume hood of a<1 equate design, face velocity, and performance reliabihty Processes carried out within gloveboxes, ordinarily 100 mci 1000 mci closed, but with possible release of iodine from process and occasional exposure to contaminated box and box leakage

• Qda'ntitiWm'ay~tle 'conshlered the cumulative remount in process handled by a worker during a 3-month peri total quantary mtroduced into a chemical or physical proceu over a 3-month period per > >d, by opening stvk reagent containers column may be used when it can be shown that activity itsfrom which radu.at tive todme may esc ape., or on one or more occasion Quan tit ie s in the rig h t -hand process is always chemically 1,ound and processed an such a manner that I-105 or I-131 will remain in nonvolatile form and dilute l to concentrations le s s than 0I mci /mg of nonvolatile agent.

the radioindine in nonfree form, and bioassay would not be necessary unless a capsule were inadvCaps o contain dropped and crushed).

when the material is in process, and the left-hand column may then be applicableIlowever, certain compounds w erten tly cipened (e. g.,

I-125 in radioimmunassay (RIA) kat s, the quantities of I-12s are very small and in less volatale. In those laboratoeies workmg only with requir emen t s may be judged from the forms, thus, bioass.ny right-hand column. In field operations, where outdoore for simple operations such as reagent contamers are opened pourmg liquid solutions, the above table does not apply - hwassay should be performed whenever an individual employee handles m open fonn (e.g., an open bottle or contamer) more th any one time.

an so mCs at opera tior s involving the rou tine use of l-125 or 1-131 in an open room or bench should be practicable, within hnods havmg adequate face velocities of 0.5 m/see or more. scaled bottles or containers holding more than 0.1 mc divou ra ged. Whenever a y O

S 330 0

8.20-4

APPENDIX A SUGGESTED REFERENCES TO ASSIST IN ESTABLISHING A BIDASSAY PROGRAM In response to public comments, this list of publications is provided to assist the licensee in estab-lishing measurements and administrative procedures for a bioassay program appropriate to his opera-tions. This list is not intended to be exhaustive and does not replace the need for professional assis-tance in establishing analytical procedures or services.

1. American NationalStandard, ANSI N44.3-1973, Radiological Protection, Pergamon Press,

" Thyroid Radiciodine Uptake Measurements Oxford, p. 17, 1968.

Using a Neck Phantom," American National Standards Institute, Inc., 1430 Broadway,

9. ICRP Publication 10A, "The Assessment of New

York, N.Y.

10018, approved Internal Contamination Resulting from August 24, 1973.

Recurrent or Prolonged Uptakes,' Recom-mendations of the International Commission

2. R. C. B rown, " 2sl Ingestions in Research on Radiological Protection,

Pergamon Personnel," Op_erational IIcalth Physics,

Press, Oxford,1969.

pp. 276-278, 1976, proceedings of the Ninth Midyear Topical Symposium of the

10. A. L. Orvis, "What Is a ' Reportable' Thy-Ifealth Physics Society, Denver, Colorado, roid Burden?" op. cit., Ref. 2., pp. 268-February 1974 (P.

Im Carson, W.

H.

271.

IIendee, and S.

C.

Ilunt, Eds., Central Rocky Mountain Chapter, IIealth Physics

11. P. Plato, A. P. Jacobson, and S. Iloman, Society, P.O. Box 3229, Boulder, Colorado "In Vivo Thyroid Monitoring for Iodine-131 80303, $15).

in the Environment," Int.

J.

Applied Radiat. an_d Isotopes, vol. 27, pp. 539-

3. E. J. Browning, K. Banerjee, and W. E.

545, 1976.

Reisinger, Jr., " Airborne Concentration of I-131 in a Nuclear Medicine Laboratory," J.

12. Radiological Protection Bulletin 25, " Safe Nucl. Med., vol. 19, pp. 1078-1081,1978.

Working with Iodine-125," National Radio-4 logical Protection Board, Ilarwell, Didcot,

4. J.

G.

Dare and A. II. Deutchman, "The Oxon, England, pp. 19-20, 1978.

Decay Scheme of Iodine-125 and Its Rela-tionship to Iodine Bioassay," op.

cit.,

13. R. P. Rossi, J. Ovadia, K. Renk, A. S.

Ref. 2, pp. 250-254.

Johnston,

and S.

Pinsky, " Radiation Safety Considerations in the Management of

5. B.

C.

Fasiska, " Radiation Safety Proce-Patients Receiving Therapeutic Doses of durn and Contamination Control Practices 18 2I," op. cit., Ref. 2, pp. 279-286.

Involved in Ifign Level I-131 Thyroid Thera-py Cases," op. cit., Ref. 2, pp. 287-291.

14. C. T. Schmidt, " Thyroid Dosimetry of 22sg and an Instrumental Bioassay Procedure,"

6. A. Gavron and Y. Feige, " Dose Distribu-Program and Abstracts: Twenty-Third An-tion and Maximum Permissible Burden of nual Conf. on~ Bioassay, Environmental, 1251 in the Thyroid Glan " liealth and Analytica1 Chemistry,

1D0-12083, Physics, vol. 23, pp. 491-499,19 /2.

Sept. 15, 16, 1977.

7. B.

Y.

Iloward, " Safe llandling of Radio-

15. A. Taylor.

J. W. Verba, N. P. Alazraki, iodinated Solutions," op. cit., Ref. 2, pp.

and W. C. McCutchen, " Monitoring of I-125 247-249.

Contamination Using a Portable Scintillation Camera," J. Nucl. Med., vol.19, pp. 431-

8. ICRP Publication 10, " Report of Pommit-432, 1978.

tee IV on Evaluation of Radiation D>ses to Body Tissues from Internal Contamination

16. Technical Reports Series No.148, " Control Due to Occupational Exposure," Recommen-of Iodine in the Nuclear Industry," Inter-dations of the International Commission on national Atomic Energy Agency, Vienna,1973.

1095 33l 8.20-5

APPENDlX 0 CALCULATION OF ACTION LEVELS FOR MlXTURES OF 1125 AND l 131 11.1 Controlling Instantaneous Thyroid Ilurdens period when air concentration data are avail-able to assess the potential exposure of the Regulatory position 4.b(1) is based on con-worker either to random single intakes or to trolling the instantaneous amount in the thy-variable or constant continuous exposures. The roid and is ta).en as 25't of the maximum per-quantities of 0.8 pCi of I-125 and 1.4 pCi of I-missible organ burden (MPOB) of I-125 or 1-131 131 were obtained by calculating 25't of the that would give a dose rate of 0.6 rem / week if total quarterly intakes of 3.2 pCi of I-125 or continuously present in the thyroid. If a mix-5.7 pCi of I-131 (see footnote 3) that would be ture of both nuclides is present in the thyroid inhaled when breathing a total of 6.3 x 108 ml and X is the fractional activity that is 1-125, a per quarter working at the standard man 3-mon th interval may be resumed when the breathing rate for 40 hours4.62963e-4 days <br />0.0111 hours <br />6.613757e-5 weeks <br />1.522e-5 months <br /> per week for 13 total activity of I-12S and I-131 is below weeks.

0.12X + 0.04(1 - X)

Example Example If the average quarterly concentrations esti-mated from air sampled in a worker's breathing If the measurements of I-125 and 1-131 in a zone are 3 x 10-8 pCi/ml for I-125 and 5 x 10-8 worker's thyroid are 0.10 pCi of I-125 and 0.05 pCi/ml for I-131, the total quarterly intakes pCi of I-131, the fractional I-125 activity is are:

X = 0.10/(0.10 + 0.05) 3 x 10-9 x 6.3 x 108 = 1.89 pCi I-125

= 0.667 5 x 10-8 x 6.3 x 10" = 3.15 pCi I-131 Total = 5.04 pCi 0.12X + 0.04(1 - X) = 0.12(0.667) + 0.04(0.33)

0.0932 Also, X, the proportien of I-125, is 1.89/5.04

0.375 Total = 0.10 + 0.05 = 0.15 pCi Thus the control level for maintaining Thus, in this case, the worker involved biweekly or more frequent bioassay checks is:

should remain on the biweekly (or more fre-quent) schedule and should not be put on the 0.8X + 1.4(1 - X) = 0.8(0.375) + 1.4(1 - 0.375) quarterly frequency.

Total = 1.18 pCi for this mixture.

B.2 Controllinx Total lntakes Since the intake of 5.04 pCi is greater than 1.18, this employee should stay on the more Regulatory position 4.h(2) is based on c6n-frequent bioassay schedule.

trolling total intakes 8 during a quarterly M

m W

W Ma a d

• The tuniting total quarterly intakes are in different propor-uons for 1-t::5 and 1-131 than are the MPoBs. This difference in the above calculations do not imply is a result of the fact that pertatas ble concentrations are any given degree of accuracy of mea-5"" elf proporuonal to effective half-lives whereas an MPoB surement. Enough digits are carried to is calculated assuming a constant burden in the organ of con-allow following the arithmetic for pur-cern that ta maintained by continuoss intake of acuvity balanced by an equai rate of etunination f, rom the organ, poses of the examples.

1095 M2 O

8.20-6

UNITE D STATES NUCLEAR REGULATORY COMMISSION I

W ASHINGTON, O. C. 20555

, gy, OFr CI AL BUSINESS u.s. NUCLE A R HE WL A TOR Y PE N ALT i FOR PRIV ATE USE, $300 E

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O 1095 333-O

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