A. INTRODUCTION 

Section 20.108, "Orders Requiring Furnishing of 

Bioassay Services," of 10 CFR Part 20, "Standards for 

Protection Against Radiation," states that the Atomic 

Energy Commission may incorporate in any license 

provisions requiring bioassay measurements as necessary 

or desirable to aid in determining the extent of an 

individual's exposure to concentrations of radioactive 

material. As used by the Commission, the term bioassay includes in vivo measurements as well as measurements 

of radioactive material in excreta. This guide provides criteria acceptable to the Regulatory staff for the 

development and implementation of a bioassay program for mixtures of the naturally occurring isotopes of 

uranium U-234, U-235, and U-238. The guide is programmatic in nature and does not deal with labora

tory techniques and procedures. Uranium may enter the 

body through inhalation or ingestion, by absorption through normal skin, and through lesions in the skin. 

However, inhalation is by far the most prevalent mode 

of entry for occupational exposure. The bioassay pro

gram described in this guide is applicable to thi 

inhalation of uranium and its compounds, but does not 

include the more highly transportable compounds UF 6 and U0 2F2 . 

Significant features of the bioassay program devel

oped in this guidb ar listed below: 

1. A bioassay program is necessary if air sampling is 

necessary for purposes of personnel protection. The 

extent of the bioassay program is determined by the 

magnitude of air sample results. 

2. A work area qualifies for the "minimum bioassay program" so long as the quarterly average of air sample results is <1% of the Derived Air Concentration (DAC) and the maximum used to obtain the average is <25% of

USAEC REGULATORY GUIDES 

Regulatory Guides we issued to describe and make available to the public rnelhods acceptable to ite AEC Regulatory staff of impmenmeting specific parts of the Cominrnstion's regulations, to delineate lechniques, -ed by the Staff in Ielliusting specific problems or postulated accidents. or to provide guidance to aplitants Reglatory Guides ore not substitutes for regulations and complianci with them is not required. Methods and solutions different from thoKi at set nm the guidlsl will be acscaptable if they provide a basts for the findings requisite to the iesuance or continuance of a permit or •icense by the Commission. 

Published •uides will be revised periodicalt-.i at apropr~ate, to accommodatei commnrs amtd to relfle new information or experience.

June 1974

GUIDE

DAC. It must be demonstrated that air sample results 

used for this purpose are representative of personnel 

exposure. 

3. Under the minimum program, bioassays are per formed semiannually or annually for all workers to 

monitor the accumulatiorý of uranium in the lung and 

bone. More frequent bioassays are performed for a 

sample of the most highly exposed workers as a check 

on the air sampling program; these bioassays are per formed at sufficient frequency to assure that a signifi cant single intake of uranium will be identified before 

biological elimination of the uranium renders the intake 

undetectable. 

4. If a work area does not qualify for the minimum 

program, bioassays in addition to the minimum program 

are performed at increasingly higher frequencies, de

pending on the magnitude of air sample results. 

5. A model is used which correlates bioassay measure

ment results with radiation .dose or with uptake of uranium in the blood (chemical toxicity). 

6. Actions are specified, depending upon the dose or uptake indicated by bioassay results. These actions are corrective in nature and are intended to ensure adequate worker protection. 

7. Guidance is referenced for the difficult task of determining, from individual data rather than models, the quantity of uranium in body organs, the rate of 

elimination, and the dose commitment. 

This bioassay program encourages improvement in the confinement of uranium and in air, sampling tech niques by specifying bioassays only to-ihe extent that confinement and air sampling can not be entirely relied 

upon for personnel protection.

C*0vPp of piutiishedguidtosmay be obtained by requet indicating the divisions testirend to the US. Atomic Energy Condmmd.on Washington D.C. 20•45, Attention. 

irorsrovesents Director of Regulatory Stan<erde. Comments and sugestions for 

of 

in t hes guides ae encouraged and Should be sent to the Secretary 

Attention: 

the Commetuon, 

Chief 

US. Atomic Energv Commission Wahington, D.C. 20545. Public Proceedings Staff. 

The uide* are issued in the following ten broad divisions: 

1. Power Reactors 6. Products 2. A emrch and Test Reactors 7. Transportation 3. Fuels med Materials Facilities 8. Occupation•l Health 4. Enronmental and Siting 9, Antitrust Review S. Meegesair and Plant Protection 10. General

U.S. ATOMIC ENERGY COMMISSION 

REGULATORY 

DIRECTORATE OF REGULATORY STANDARDS 

REGULATORY GUIDE 8.11 

APPLICATIONS OF BIOASSAY FOR URANIUM
B. DISCUSSION 

The topics treated in this guide include determining 

(1) whether bioassay procedures are necessary, (2) which 

bioassay techniques to use and how often, (3) who 

should participate, (4) the action to take as based on 

bioassay results, and (5) the particular results which 

should initiate such action. Taken together, these topics 

comprise an exposure control program. Technical bases 

for the criteria appearing in the guide are provided in 

"Applications of Bioassay for Uranium," WASH-1251, 

which is available from the Superintendent of Docu

ments, U.S. Government Printing Office, Washington, 

D.C. 20402. 

After an exposure to uranium has occuired, the 

difficult problems of estimating the quantity present in 

the body and the anticipated dose commitment arise. 

This subject is treated in considerable detail in WASH

1251. 

C. REGULATORY POSITION 

!. Special Terminology 

Several of the terms used in this guide have been 

given special definitions and are listed in this section for 

the convenience of the reader. 

Bioassay - The determination of the kind, quantity 

or concentration, and location of radioactive 

material in the human body by direct (in vivo) 

measurement or by analysis of materials excreted 

or removed from the body. 

Derived Air Concentration (DAC) -- Equivalent to 

the concentrations listed in Appendix B to 10 

CFR Part 20. 

Dowe Commitment (Dc) -- The total radiation dose

equivalent to the body or specified part of the 

body that will be received from an intake of 

radioactive material during the 50-year period 

following the intake. 

Exposure - The product of the average concentration 

of radioactive material in air and the period of 

time during which an individual was exposed to 

that average concentration (jICi-hr/cc). 

Intake - The quantity of radioactive material 

entenng the nose and/or mouth during inhalation; 

the product of the exposure and the breathing 

rate. 

In Vivo Measurements - Measurement of gamma or 

X-radiation emitted from radioactive material 

located within the body, for the purpose of 

estimating the quantity of radioactive material 

present.

Maximum Permissible Annual Dose (MPAD) The 

annual maximum occupational radiation dose 

recommended by the ICRP for the body or part ul' 

the body. 

Maximum Permissible Dose Commitment (MPDc) 

A dose commitment numerically equivalent to the 

Maximum Permissible Annual Dose. 

Measurement Sensitivity Limit The smallest quan

tity or concentration of radioactive material that 

can be measured with a specified degree of 

accuracy and precision. 

Nontransportable- Slowly removed from the pul

monary region of the lung by gradual dissolution 

.in extracellular fluids, or in particulate form by 

translocation to the GI tract, blood, or lymphatic 

system; Class (W), nontransportable dust with 

50-day biological half-life in the lung. Class (Y), 

nontransportable dust with 500-day biological 

half-life in the lung. 

Transportable- Dissolved upon contact with extra

cellular fluids and translocated to the blood- Class 

(D), transportable dust with rapid clearance from 

the lung. 

Uptake -- The quantity of radioactive material enter

ing the nose and/or mouth during inhalation that 

is not exhaled and enters extracellular fluids. 

w/o U-235 Percentage by weight of the isotope 

U-235 in a mixture of U--234, U-235, and U-238 

(w/o U-235 in natural uranium is 0.72). 

2. Programmatic Guidance 

The following programmatic guides are applicable 

where personnel are occupationally exposed to uranium 

in respirable form and in sufficient quantity that 

measurements of uranium concentrations in air are 

considered to be necessary for the protection of workers 

in ccmpliance with Regulatory requirements, including 

license conditions. 

a. Basic Requirements and Minimum Capabilities 

The following guides establish basic requirements 

and minimum capabilities which should he found in a 

program for protection against internal exposure from 

operations with uranium: 

(1) Responsibilities foi protection against ura

nium contamination should be weil defined and under

stood by all personnel concerned and should be specified 

in direct;ves from management 

(2) A comprehensive and technically sound protec

tion program should be developed and implemented.

8.11-2 L

I
(3) Personnel, space, equipment, and support 

resources should be provided as necessary to conduct the 

program. 

(4) An effective method of periodic internal audit 

of the protection program should be maintained. 

(5) Before assigning employees to work in an area 

where exposure to uranium contamination may occur, 

action should be taken to ensure that facility and 

equipment safeguards necessary for adequate radiation 

protection are present and operable, that the employees 

are properly trained, that adequate procedures are 

prepared and approved, that an adequate surface and air 

contamination survey capability exists, that a bioassay 

program at least equivalent to the program described in 

this guide will be maintained, and that survey and 

bioassay records will be kept. 

b. Bioassay Program 

In the development of a bioassay program the 

following guides should be implemented: 

(1) Necessity 

The determination of the need for bioassay 

measurements should be based on air contamination 

monitoring results in accordance with criteria contained 

in this guide. 

(2) Preparatory Evaluation 

Before assigning an employee to work in an 

area where substantial exposure to uranium contami

nants may occur, his condition with respect to radio

active material of similar chemical behavior previously 

deposited and retained in his body should be determined 

and the necessity for work restrictions evaluated. 

(3) Exposure Control 

The bioassay program should include, as appro

priate, capabilities for excreta analyses and in vivo 

measurements, made separately or in combination at a sufficiently high frequency to assure that engineered 

confinement and air and surface contamination surveys 

are adequate for employee protection. The program 

should include all potentially exposed employees. 

(4) Diagnostic Evaluation 

The bioassay program should include capabili

ties for excreta analyses and in vivo measurements as 

necessary to estimate the quantity of uranium deposited 

in the body and/or in affected organs and the rate of 

elimination from the body and/or affected organs.

3. Operational Guidance 

a. Criteria for Determining the Need for a Bioasay 

Program 

Where air sampling is required for purposes of 

occupational exposure control, bioassay measurements 

are also needed (Table 1) The bioassay frequency 

should be determined by air sample results as averaged 

over I quarter. 

Testing should be performed to determine whether 

awi sampling is representative of personnel exposures. Air 

sample results which have been verified as representative 

may be used to determine the quarterly average. 

If the 1-quarter average does not exceed 10% of 

the appropriate Derived Air Concentration (DAC) from 

Appendix B to 10 CFR Part 20 and if the maximum 

result used in the calculation of the average does not 

exceed 25% of DAC, only a minimum bioassay program 

is necessary (Table 2). If the 1-quarter average exceeds 

10% DAC, or if the maximum result exceeds 25% of the 

DAC, additional bioassays are necessary (Table 3), 

except as noted below. Frequency criteria for both cases are discussed in Section C.3.c. The approach is illus

trated in Figure 1. 

The additional bioassays are not performed for a specific individual if the licensee can demonstrate that 

the air sampling system used to protect the individual is 

adequate to detect any significant intake- and that 

procedures exist for diagnostic bioassays following 

detection of an apparently large intake. 

The necessity for bioassay measurements may also 

arise following an incident such as a fire, spill, equip

ment malfunction, or other departure from normal 

operations which caused, or could have caused, abnor

mally high concentrations of uranium An air. Criteria for 

determining this necessity are shown in Pigure 2. (The 

term "Early Information" refers to an instrumented air 

sampler with an alarm device.) Reliance cannot be 

placed on nasal swab results from mouth breathers. 

bioassays should be performed. 

Special bioassay measurements should be per

formed to evaluate the effectiveness of respiratory 

protection devices. If an individual wearing a respiratory 

protection device is subjected to a concentration of 

transportable uranium in air within a period of I week, 

such that his exposure with no respiratory protection 

device would have exceeded 40 x DAC ,Ci-hr/cc, 

urinalysis should be performed to determine the result

ing actual uranium uptake. If an individual wearing a

8.11-3
TABLE I 

SELECTION OF BIOASSAY MEASUREMENT TECHNIOUES

Transportable Non transportable 

Purpose Compounds Compounds 

Choice of Measurement 

1st 2nd' 3rd 

Preparatory Evaluationb uc ivc fr u 

Exposure Control 

Check on Air Sampling Program u iv f u 

Monitoring of Lung Burden Buildup - iv f u 

Monitoring of Bone Burden Buildup u u 

Detection of Unsuspected Intake u iv f 

Diagnostic Evaluation u iv f u 

Work Restriction Removal i iv f u 

alf for any reason air sampling is not adequately effective, and the appearance of urinary uranium is long delayed by extreme 

nontransportability, the buildup of uranium in the lung pmay continue undetected until a positive in vivo result is obtained. Fecal 

analysis is an excellent and highly recommended early indicator in such cases. Fecal analysis should be considered if in vivo 

measurements are too infrequent to permit early identification of an unfavorable trend. 

bDiagnostic evaluation necessary if results are positive. 

Cu, urinalysis; f, fecal analysis; iv. in vivo.

respiratory protection device is subjected to a concen

tration of nontranrsportable uranium in air within a 

period of 13 weeks, such that his exposure with no 

respiratory protection device would have exceeded 

520 x DAC jiCi-hr/cc, the resulting actual uranium 

deposition in the lung should be determined using in 

vivo measurements and/or fecal analyses. These special 

bioassay procedures should also be conducted if for any 

reason the magnitude of the exposure (with no respira

tory protection device) is unknown. 

b. Selection of Measurement Techniques 

The appropriate selection of bioassay techniques 

appears in Table 1. Preparatory evaluation refers to 

bioassays performed for job applicants or existing 

employees prior to an assignment involving potential 

exposure to uranium. Exposure control refers to bio

assays performed to assure that engineered confinement 

and the air sampling program are sufficiently effective in 

the control and evaluation of exposures. Diagnostic 

evaluation refers to bioassays performed following a 

known significant exposure. These evaluations are per

formed to determine the location and magnitude of 

uranium deposition, which would in turn aid in deter

mining whether therapeutic procedures are indicated and 

whether work restrictions are necessary. The evaluations

would also aid in estimating the retention function and 

dose commitment. Work restriction removal refers to 

bioassays performed for employees who, because of past 

depositions of radionuclides, have been restricted by 

management in their work involving exposure to radio

active material until the magnitude of such depositions is 

reduced sufficiently to permit the removal of these work 

restrictions. 

c. Selection of Measurement Frequency 

Acceptable frequencies for the minimum bioassay 

program are given in Table 24Table 3 gives acceptable 

frequencies when additianal bioassay measurements are 

necessary to detect unsuspected single intakes, unless the 

measurement capability is the limiting factor. Figures 3 

through 7 present the maximum time between measure

ments based on measurement sensitivity considerations; 

the figures should be used to determine the measure

ment frequency unless the interval specified in Table 3 is 

shorter. The Class (W) curve in Figure 5 may be used for 

Class (Y) materials if it is known that Class (D) or Class 

(W) materials are present. 

Table 2 specifies, for the minimum program, 

semiannual or annual bioassays for monitoring the 

accumulation of uranium in the lung and bone, plus

8.11-4
TABLE 2 

BIOASSAY FREQUENCY FOR EXPOSURE CONTROL

Program Objective Dust Measurement Frequency Classification Techniquea 

Check on air sampling (D) u Use Figures 3 and 4 

program and on con- (W) iv Use Figure 6 

finement procedures (Y) iv Semiannual 

Minimum" and equipment. 

Adequate if Monitor lung burden (W) iv AnnualF 

QA < I/ I 0DA( buildup. (Y) iv Serruannualc 

and M < 1/4 DAC 

Monitor bone burden (D) u Semiannual 

buildup. (W) u Semiannual 

(Y) u Class (D) or Class (W) Not Present, Annuald 

(Y) u Class (D) or Class (W) Present, Semiannuald 

Additional Detect unsuspected (D) u Use Table 3e 

intake. (W) iv, f, or u Use Table 3 e Acceptable it (Y) iv, f. or u Use Table 3e 

QA > 1/10 DAC 

and/or M > 1/4 DAC 

aiv, n vivo; u, urinalysis; f, fecal analysis. 

bQA, quarterly average of air sample results; M, maximum result used to determine QA 

CThese frequencies are applicable if no individuals are near work restriction limits. Quarterly or even monthly iv may become necessary as workers approach these limits 

dSpecial urinalysis should be performed each time exposure to new Class (Y) material begins to determine if more transportable component is present. eThese measurements are additional to those listed above for the minimum program. If it is demonstrated that air sampling provided for a specific individual is adequate to detect any sigmficant intake and that procedures exist for diagnostic bioassays following detection of an apparently large intake, these additional measurements need not be performed.

(

00
TABLE 3 

FAEQUENCYa FOR ADDITIONAL BIOASSAYS BASED ON CONCENTRATION OR EXPOSURE 

QA Most recent quarterly average of concentration or most recent quarterly average of weekly exposures 

M Maximum result used in the calculation of the quarterly average 

u urinalysis 

iv - it vivo 

Multiply numbers in first column by DAC pCi/cc or by 40 DAC pCi-hr/cc. Frequencies are given in bioassaysper year 

at equally spaced intervals.

Air Sample Results Class (D) Class(W) 

u U iv

Class (Y) 

ub iv

O<QA< 1/10 

1/4<M< I 

I <M< 10 

10<M 

I/i0<QA< 1/4 

0<M< I 

I <M<10 

10< M 

1/4<QA< 1/2 

C<M< I 

i<M< !0 

ii < M

4 

12

4 

12

2c 

4 

12 

12 

26

1i2<QA< I 

0<M< 10 

10<M

2 

4 

12 

2 

4 

12 

4 

12 

26 

26 

52

1 

2 

4

1 

2 

4 

2 

4 

12 

12 

12

2 

4 

12 

4 

12 

26 

12 

26 

52 

26 

52

2 2 

4 

4 

4

4 

4 

12 

12 

12

a Low frcqucncicý indicated may be precluded by measurement capability limitations: see Figures 3 through 7 

bAppicable if Class (D) or Class (W) materials are known to be present;convert 52 and 26 to 12 if they are not present. Fecal analysis 

may be substituted for urinalysis. 

c Frequency possible only for high w/o U-235; naturally occurring urinary uranium prohibits detection otherwise.

more frequent bioassays (based on measurement sensi

tivity) to check on the air sampling program. Section 

C.3.d indicates that all workers should participate in the 

bioassay program for purposes of monitoring the organ 

buildup, while only a sample of workers is sufficient for 

checking the air sampling program. If a working area 

does not qualify for the minimum program, additional 

bioassays are specified in Table 3 at somewhat higher 

frequencies. Any urinalysis procedure performed for one 

of these purposes may be used to satisfy a urinalysis 

requirement for another purpose, provided the fre

quency criteria are met. A similar statement may be 

made regarding in vivo measurements. 

The purpose of the additional bioassay measure

ments is the timely detection of unsuspected exposures 

not detected by the air sampling program. Therefore, the 

additional bioassays are not necessary for an individual

who is protected by a monitoring system that essentially 

assures detection of any significant intake. 

Although fecal analysis is not shown in Table 3, 

this procedure is preferred over urinalysis for Class (W) 

and Class (Y) materials and may be substituted for 

urinalysis in the table. If in vivo measurements are made 

at the frequency shown for urinalysis, Class (W) and 

Class (Y), the unnalyses are unnecessary; the urinalyses 

prescribed in Table 2 are adequate. 

The bioassay measurement frequency, as deter

mined from Table 2 or 3 (or the associated figures), 

should not be decreased because of consistently low 

bioassay results; bioassay measurements are needed as a 

final check on the contamination confinement capability 

and on the effectiveness of the air sampling program. 

Consistently high bioassay results may suggest that more

8.11-6
frequent bioassays should be performed even though 

there is no such indication from air samples. In this case, 

however, improvements in the air sampling program are 

required rather than more frequent bioassays. The 

appropriate frequency can be determined from air 

sample data if the air sampling program is adequately 

representative of inhalation exposures. 

If workers are exposed to a mixture of uranium 

compounds, the DAC for the mixture, DACm, should be 

calculated as

Dn= [i, f DACm Zi DAC1

]

-I

where DACi is the DAC for the ith compound and fi is a 

fraction representing the contribution of the ith com pound. The calculation of fi depends on the exposure 

mode. If the material is a mixture, fi is the activity 

fraction. For exposure in more than one area, fi is the 

time fraction spent in the ith area. As an alternative 

DACm may be taken as the lowest DACi. As to the 

quarterly average for air samples, if the material is a mixture and exposure occurs in only one area, the 

quarterly average calculation, applicable to all workers in 

the area, should be performed as for non-mixtures, i.e., 

from samples characterizing conditions in the area. If 

exposures occur in several areas, the quarterly average 

for the mixture may be a time-weighted average for the 

individual, using ( arterly average air samples that 

characterize full-time conditions in each area. i.e., 

n 

QAm = 2 fi QAi 

i=l 

where QAi is the quarterly average for the ith area and fi 

is the time fraction of the quarter that the individual 

worked in the ith area. As an alternative, QAm may be 

taken as the highest QAi. 

Figure 5 indicates that a urinalysis measurement 

sensitivity of about 0.7 pCi/I is required to detect the 

equivalent of I MPDc following a single exposure to 

Class (Y) materials with neither Class (D) nor Class (W) "'tracer" dusts present. To obtain this sensitivity, a 

chemical concentration procedure is necessary. Fecal 

analysis is recommended as an alternative, using the 

frequency schedule given for urinalysis. 

If work restrictions that have been imposed do not 

involve total exclusion from restricted areas, it is 

necessary to ensure that bioassay measurements made 

for the purpose of removing work restrictions are 

performed at least as frequently as would be required for 

purposes of exposure control.

A monthly in vivo frequency may be reduced to 

quarterly if weekly fecal analyses are made, with an in 

vivo measurement at the end of the quarter. An in vivo 

measurement should be performed as soon as practicable 

if the excretion rate exceeds 7 pCi/day Class (Y) or 700 

pCi/day Class (W). For lower results the following 

procedure should be followed. Results from the first 4 

weekly specimens should be plotted (semilog) against time, and a best fitting curve should be extrapolated to t = 0. thus obtaining an estimate of the initial excretion 

rate, (dP Idt)o, and the individual's half-lifel T. The dose 

commitment, Dc, should be estimated using these values 

with the following equation:

Dc= 8.4 T2 [

where T is in days and (dP/dt)o is in MOCt/day. The 

actions indicated in Table 4 should then be taken. This 

procedure should be repeated at the end of 8 weeks 

when results from 8 specimens are available. At the end 

of the quarter D. should be evaluated using results from 

all 12 specimens. If the indicated Dc is < 3 rems, the in 

vivo measurement may be considered unnecessary If the 

Dc indicated by the fecal data exceeds 3 reins, the in 

vivo measurement should be performed. 

A quarterly in vivo frequency may be reduced to 

semiannual if monthly fecal analyses are made, with an 

in vivo measurement at the end of 6 months If any result exceeds 7 pCi/day Class (Y) or 460 pCi/day Class 

(W). an in vivo measurement should be performed as 

soon as practicable. For lower results the following 

procedure should be followed. Results from the first 3 

specimens should be plotted (semilog) against time, and 

a best-fitting straight line should be extrapolated to 

t= 0. Values for (dP /dt)o and T for the individual 

should be obtained and used in the above equation to 

estimate Dc. The actions indicated in Table 4 should 

then be taken. At the end of the fourth and fifth month, 

Dc should again be evaluated using results from all 

specimens. At the end of the 6-month period, the in vivo 

measurement should be performed. 

Fecal specimens used for this purpose should be 

obtained after 2 or more days of no exposure. In the 

extrapolation of excretion rate data to t= 0. it is 

necessary to ignore data points obtained for less than 2 

days after exposure. 

d. Participation 

All personnel whose regular iob assignmentN involve work in an area where bioassay ineasurernenI,, are required should participate in the bioassay program However, as long as air sainple results qualify the area 

and group of workers tor the minimum bioasssa 

program, special consideration may be given in the case

8.1 1-7
of bioassays obtained for the purpose of checking on the 

air sampling program, i.e., the first objective shown in 

Table 2. For these bioassays it is acceptable to limit 

participation to a representative sample of the group. 

The sample should be composed of the most highly 

exposed or potentially exposed personnel and should 

include at least 10% of the workers who have regular job 

assignments in the area if the total number of such 

workers is 100 or more. If the total is between 100 and 

10 workers, there should be 10 participants. If the total 

is less than 10 workers, all should participate. Thus, 

where the minimum bioassay program is being con

ducted, all workers would participate either semi

annually or annually for monitoring of uranium buildup 

in the lung or bone, in addition, those in the sample 

group would participate more frequently if required to 

do so by Figures 3, 4, or 6. (Note that the in vivo 

frequency for Class (Y) materials is semiannual in every 

case.) This sampling procedure will be of particular 

usefulness to those using Figure 4. Where bioassays in 

addition to the minimum program are conducted, all 

workers should participate (see Table 2, footnote e, for 

exception). 

Personnel whose duties involve only observance 

and who spend less than 25% of the work week in areas 

where bioassay is required may participate on a limited 

basis. The interval between bioassay measurements for 

such personnel should be a matter of judgement based 

on the magnitude of the exposure. 

e. Action Based on Results 

Appropriate action as based on bioassay results is 

dependent first on the underlying purpose of the 

measurement. 

(!) Preparatory Evaluation 

Where urinalysis for uranium is used to screen 

personnel prior to job assignment, the presence of any 

urinary uranium, as detected by routine laboratory 

procedures, should trigger an investigation. Information 

regarding the location and quantity of uranium in the 

body should be sought, and conservative predictions as 

td future retention in the body should be made. This 

information can usually be derived from a review of the 

worker's previous exposure history, including previous 

bioassay results, and from subsequent bioassay measure

mrents as necessary. Findings should be compared with 

criteria given in Section C.3.f.(8), or with other accept

able criteria, and a decision should be made to approve 

the job assignment if acceptable criteria are met, or to 

impose a delay otherwise. 

(2) Exposure Control 

When work is in progress, and bioassay mea

surements are being made routinely, it is essential to

ensure that the measurement results are carefully 

reviewed by qualified personnel and that appropriate 

action is taken if the results are considered high. Action 

should be based on the organ burden, the dose commit

ment, or chemical damage to the kidney as indicated 

(however roughly) by the result. Appropriate actions are 

shown in Tables 4 and 5 for single intakes. In the case of 

chronic exposure, when bioassay results indicate that the 

organ burden is continuing to rise, action should be 

taken to assure that additional buildup will not interfere 

with the worker's career. When urinalysis indicates 50% 

or more of the maximum permissible lung burden for 

nontransportable uranium, in vivo measurements should 

be undertaken. Work restrictions should be tmposed 

without waiting for in vivo measurements if urinalysis 

indicates more than I permissible lung burden. 

(3) Diagnostic Evaluation 

Diagnostic bioassay measurements are made to 

.estimate the quantity and distribution of radionuclides 

in the body after determination that a large deposition 

has occurred. Actions to be based on diagnostic results 

include (I) selection of subsequent measurement tech

niques and frequencies, (2) imposition or removal of 

work restrictions, (3) referral to a physician, and (4) the 

physician's decision to attempt acceleration of the 

nuclide elimination process. 

f. Action Points 

This -section presents acceptable correlations be

tween organ burden, dose commitment, or uranium 

uptake and the quantities actually measured using 

bioassay techniques, thus providing action point criteria 

for purposes of exposure control. Guidance is also given 

for work restrictions and for referral to a physician. 

These correlations are derived entirely from 

models. This approach is acceptable for purposes of 

exposure control. However, these correlations would 

actually predict the dose commitment or uranium 

uptake only if the bioassay result was without error and 

if every condition of the models was actually achieved. 

(1) Dose Commitment and Uptake Correiations, 

Single Intake, Class (D) Dust 

The correlation between dose commitment to 

the bone and urinary uranium concentration is shown in 

Figure 8 for Class (D) materials. In the right hand margin 

of the figure the recommended actions, from Table 4, 

are indicated. The correlation between uptake of 

uranium by the blood and urinary uranium concen

tration is shown in Figure 9 for Class (D) materials. 

Recommended actions, from Table 5, are indicated.

8.11-8
TABLE 4 

ACTION DUE TO BIOASSAY MEASUREMENT RESULTS, RADIATION DOSE 

Result < 1/5 MPDca 

Contamination confinement and air sampling capabilities are confirmed. No action required. 

1/5 < Result < 1/2 MPDc 

Contamination confinement and/or air sampling capabilities are marginal. If a result in this range was expected because 

of past experience or a known incident, any corrective action to be taken presumably has been or is being 

accomplished; no action is required by the bioassay result. If the result was unexpected: 

(I) Confirm result (air sample data review, comparison with other bioassay data, additional bioassay measurements). 

(2) Identify probable cause and, if necessary, correct or initiate additional control measures. 

(3) Determine whether others could have been exposed and perform bioassay measurements for them. 

(4) If exposure (indicated by excreta analysis) could have been to Class (W) or Class (Y) dust, consider the perfor

mance of diagnostic in vivo measurements. 

1/2 < Result < 1 MPDc 

Contamination confinement and/or air sampling capabilities are unreliable unless a result in this range was expected 

because of a known unusual cause, in such cases, corrective action in the work area presumably has been or is being 

taken, and action due to the bioassay result includes action (7) only. Conditions under which a result in this range 

would be routinely expected are undesirable. If the result was due to such conditions or was actually unexpected, take 

actions (1) through (4) and: 

(5) If exposure (indicated by excreta analysis) could have been to Class (W) or Class (Y) dust, assure that diagnostic in 

vivo measurements are performed. 

(6) Review the air sampling program, determine why air samples were not representative and make necessary 

corrections. 

(7) Perform additional bioassay measurements as necessary to make a preliminary estimate of the critical organ 

burden; consider work limitations to ensure that the MPDc is not exceeded. 

(8) If exposure could have been to Class (Y) dust, bring expert opinion to bear on cause of exposure, and continue 

operations only if it is virtually certain that the limit of I MPDc will not be exceeded by any worker. 

Result > I MPDc 

Contamination confinement and/or air sampling capabilities are not acceptable, unless a result of this magnitude was 

expected because of a known unusual cause: in such cases, corrective action in the work area presumably has been ov is 

being taken, and action due to the bioassay result includes actions (10) and (11) only. Prevalent conditions under which 

a result in this range would be expected are not acceptable. If the result was due to such conditions or was actually 

unexpected, take actions(I) through (7) and: 

(9) Take action (8), regardless of dust classification. 

(10) Establish work restrictions as necessary for affected employees. 

(11) Perform individual case studies (bioassays) for affected employees. 

aThe annual MPDC is a 50-yr integrated dose of 15 rems to the lung or 30 reins to the bone.

8.11-9
TABLE 5 

ACTION DUE TO BIOASSAY MEASUREMENT RESULTS, CHEMICAL TOXICITY 

Result < 1/2 L4 

Contamination confinement and air sampling capabilities are adequate. No action required. 

1/2 L < Result < L 

Contamination confinement and/or air sampling capabilities do not provide an adequate margin of safety. If a result in 

this range was expected because of past experience or a known incident, any corrective action to be taken presumably 

has been or is being accomplished; no action is required by the bioassay result. If the result was unexpected: 

(1) Confirm result (air sample data review, comparison with other bioassay data, additional bioassay measurements). 

(2) Identify probable cause and, if necessary, correct or initiate additional control measures. 

(3) Determine whether others could have been exposed and perform bioassay measurements for them. 

(4) Determine why the bioassay result was not predicted by the air sampling program and make necessary corrections. 

(5) Consider work limitations to ensure that L is not exceeded. 

(6) If bioassay result was near L, bring expert opinion to bear on cause of exposure, and continue operations only if it 

is virtually certain that L will not be exceeded by any worker. 

Result > L 

Contaminatiow confinement and/or air sampling capabilities are not acceptable, unless a result of this magnitude was 

expected because of a known unusual cause; in such cases, corrective actuon in the work area presumably has been or is 

being taken, and action due to the bioassay result includes actions (7) and (8) only. Prevalent conditions under which a 

result in this range would be expected are not acceptable. If the result was due to such conditions or was actually 

unexpected, take actions ( I ) through (6) and: 

(7) Establish work restrictions as necessary for affected employees. 

(8) Have additional urine specimen tested for albuminuria under direction of a physician. 

aL is 2.7 ing of uranium in the bWood. Assume uptake is 43% of intake.

(2) Class (D) Dust, Dual Action Requirements 

If the urinary uranium concentration is suf

ficiently large, action due to both radiation dose and 

chemical toxicity may be necessary. Both Figures 8 and 

10 should be consulted for this determination. Figure I I 

presents values of specific activity acceptable for con

verting activity to gravimetric units. 

For exposure to multiple enrichments, values 

from Figure 11 should be weighted to obtain an 

appropriate specific activity. If the weighting factors are 

unknown, the smallest specific activity present shou!d be 

used.

(3) Dose Commitment Correlation, Single Intake, 

Class (W) and Class (Y) Dust, Excreta Analysis 

The correlation between dose commitment to 

the lung, urinary uranium concentration, and uraniuirn 

fecal excretion rate is shown in Figures 12 through 14 

for Class (W) and Class (Y) materials. Recommended 

actions, from Table 4, are indicated. 

(4) Dose Commitment Correlation, Single Intake, 

Clan (W) and Class (Y) Dust, In Vivo 

The correlation between dose commitment to 

the lung and the mass of U-235 measured in the thorax

8.11-10

I
by in vivo techniques is shown in Figure 15 for Class (W) 

materials and in Figure 16 for Class (Y) materials. 

Recommended actions, from Table 4, are indicated. 

These figures are applicable to uranium of 20 w/o 

U-235; scaling factors are provided in Figure 17 for 

other enrichments. 

(5) Exposure to Mixtures 

If a positive urinalysis specimen is obtained 

following exposure to a mixture that included significant 

quantities of Class (Y) materials, actions (1) through 

(11) in Table 4 should be taken. 

if the exposure was to a mixture of Class (W) 

dust and-Class (D) dust with chemical toxicity limiting, 

the urinary uranium mass concentration should be 

determined and the curves in Figure 9 used to determine 

the required actions from Table 5; the activity concen

tration should also be determined, using Figure 12 with 

Table 4. 

If exposure was to a mixture of Class (W) dust 

and Class (D) dust with bone dose limiting, it is 

necessary to estimate the fraction of the dust inhaled 

that was Class (W), fw, and the fraction that was Class 

(D), fd. It is also necessary to determine the urinary excretion factors, Ew and Ed, that would be applicable 

at the timie the specimen was obtained; Figure 18 may be used for this purpose. If R represents the bioassay 

result in pCi/day, Rd the Class (D) component and Rw 

the Class (W) component, such that R = Rd + Rw, then 

Rd = fdEdR/(fdEd + fwEw) 

aw = fwEwR/(fdEd + fwEw) 

These results should be converted to concentra

tion using the factor 1.4 I/day. Then the curves in 

Figure 8 or Figure 12 should be used to determine the 

required actions from Table 4. 

If positive in vivo results are obtained following 

exposure to a mixture of Class (W) and Class (Y) 

materials, Figure 16 should be used to determine the 

required actions from Table 4. 

(6) Lung Burden Correlations, Continuous Intake 

In some working areas airborne uranium is 

routinely present and is responsible for the chronic 

appearance of uranium in urine. Continuous intakes of 

this nature may also be responsible for chronically 

positive in vivo measurement results. Under these condi

tions positive bioassay results are expected, and the 

monitonng tasks are to measure the lung burden buildup 

and to identify single intake peaks above this expected level. Thus it is evident that for purposes of exposure

control the chronic levels due to continuous intake do 

not alter the approach outlined for the detection of 

single intakes. 

The correlation between in vivo measurements 

of U-235 and lung burden is shown in Figure 19. In.vivo 

measurements are considered to be much more reliable 

than urinalysis for Class (W) and Class (Y) materials. 

However, urinalysis may be used to indicate that in vivo 

measurements are promptly needed. rThe average value 

from several urinalysis results (R) can be used with 

Figure 20 to estimate the number of maximum per

missible lung burdens (MPLB = 0.016 pCi). Arrange

ments for in vivo measurements should be undertaken 

when AR is found to exceed 0.5. If ý'R >1, additional 

exposure should be avoided until in vivo results are 

available. 

(7) Referral to a Physician 

When confirmed bioassay measurement results 

indicate that the Maximum Permissible Annual Dose 

(MPAD) to the lung or bone has been or will be 

exceeded by a factor of 2, the affected individual should 

be so informed, and referral to a physician knowledge

able in the biological effects of radiation and conversant 

in the nature and purpose of regulatory dose limits 

should be considered. 

When confirmed bioassay results indicate that 

an exposure to uranium has resulted in an uptake by the 

blood of more than 2.7 mg within 7 consecutive days or 

less, the affected individual should be informed of his 

exposure and referred to a physician knowledgeable in 

the chemical effects of internally administered uranium. 

(8) Work Restrictions 

AEC regulations establish an upper limit on 

exposures during a specified period of time; it follows 

that work restrictions may be necessary to prevent 

exposures from exceeding this limit. Such restrictions 

may also be necessary to prevent the deposition of 

uranium in the body in such quantity that: 

(i) the mass of uranium entering the blood 

will exceed 2.7 mg in 7 consecutive days; (ii) the activity present in the lung will pro

duce an annual dose-equivalent to the 

pulmonary region exceeding 15 reins; 

(iii) the activity present in the bone will 

produce an annual dose-equivalent to the 

bone exceeding 30 reins. 

For personnel who have a body burden of 

uranium that is producing an annual dose-equivalent 

greater than 15 rems to the pulmonary region of the 

lung or 30 reins to the bone or both, work restrictions

8.111-11
may be imposed as necessary to assure that the 

additional radiation dose from sources under the control 

of the employer would be considered negligible by a 

qualified health physicist. 

4. Diagnostic Guidance 

In previous sections a monitoring program has been 

described which should detect every instance of serious 

deposition of uranium in the body. Once a deposition of 

this nature has been identified, the bioassay purpose 

changes from exposure control to diagnosis. With respect

to chemical toxicity, the objective is to determine 

whether the uranium uptake was sufficient to cause 

kidney damage. The radiological objectives are to esti

mate (1) the quantity of uranium present in the organ of 

reference, (2) the rate of elimination, (3) the magnitude 

of the original deposition, and (4) the dose commitment. 

As with exposure control monitoring, use of models is 

necessary. However, it is usually possible in a given 

individual's case to use factual data rather than some of 

the assumptions, and every opportunity for such refine

ment .should be taken. This subject is treated in 

considerab!e detail in WASH-1251, Section V.

8.11-12

I
A4R SAMPLING DATA 

NOT REPRESENTATIVE I REPRESENTATIVE

1 - QTR. AVE,_<10% DAC 1 - QTR. AVE.>10% DAC 

MAXIMUM_< 25% DAC MAXIMUM >25% DAC

USE OF NON-REPRESENTATIVE AIR 

SAMPLING DATA IS NOT ACCEPTABLE 

IN DETERMINING THE 1 - QTR. AVE.

[MINIMUM BIOASSAY PROGRAM]

SADDITIONAL BIOASSAYS I

Figure 1 Criteria for Initiating Additional Bioassays, Routine Conditions

Figure 2 Criteria for Diagnostic Bioassays Durings Special Investigations

8.1 1-13
~i2 

LU 

z 

wig 

laj 

010 

100 101 102 10310 

MEASUREMENT SENSITIVITY LIMIT (pCi/I) 

Figure 3 Maximumn Time Between Specimens to Detect 1 MPDc, 

Class (D) Uranium Dust, w/o U-235 >80
3 1 1I I I TI I1 l I1111 " V! IIIT _ 

S102

u - USE FIGURE 11 TO CONVERT 

TO ACTIVITY UNITS. 

wI 

9- 0 

uJ 101 -

100 - I I 11111 I 111 X 1 I 1 11111 III1 I I I I 

10-1 100 101 102 103 104 

MEASUREMENT SENSITIVITY LIMIT (pg/I) 

Figure 4 Maximum Time Between Specimens to Detect Uptake of 

2.7 mg Class (D) Uranium, w/o U-235:580

,
6 .I-12..

z Lu 

z 

UA 

2 

uj

100 , I 1 1 1 Hill I 

101 102 

MEASUREMENT SENSITIVITY

Lo3 

LIMIT (pCi/I)

10 

10

I I I I I III I I I (iiY) 

CLASS (Y)

q_

I I I I I Iif I I

10-1 100 101 

MEASUREMENT SENSITIVITY LIMIT (pCi/I)

Figure 5 Maximum Time Between Specimens to Detect 1 MPDc, 

Class (W) or Class (Y) Uranium

V

•llv I A L= a ..... . . . . ....

103 4

0 WJ

2
I I 1 1111 i I I 1111U I I 111111 I I I 11111 

20 w/o U-235

93% U-235

I ! I III_

III', I. I 4 6-.

z 

Ln 

U. 

2 

Iz 

Lu 

Lu 

U.1 cn 

w 

uz 

t-.

101

I I I IIIll I I I IIIII I I 1 11111 I I I I I lll

102 103 

MEASUREMENT SENSITIVITY LIMIT (pg U-235)

Figure 6 Maximum Time Between Measurements to Detect 1 MPDc 

In Vivo, Class (W)

-- I

I'j

--4

102 

.- I,,

I I I I I III 1001 

100

w

-- . . - I . . I . .. -- .. . . . . .. . . . . . II 1 1 1 1 1 1

C

IV

i
TIME BETWEEN MEASUREMENTS (DAYS) 

._ 0 

--- f:• T• F 

c m "os m 

Zm 

00 

m 

a *
103

~~~~~~~ ,,t,/ 3ris1M~ -- TABLE 

LL .7 ... ....... ....... ...... 'w mm 

C N 

0 

2 6 rams 

I- / 

RESU 

w 

0 10"0 

N( 

10-21 1 ItI I I l 1 

100 101 102 103 

URINARY URANIUM CONCENTRATION (pCi/I) 

Figure 8 Dose Commitment Indicated by Model vs. Urinary Uranium 

Concentration, Class (D), Single Intake

8.11-19
104I 1 I 1 1 I 1II I l I I I 

103 

E 

-j 

S10 ,o 2 

a 100 

0 

U

CL100 

AI 

10.1 ........ .. / .. .. I 

10- 100 101 102 

URINARY URANIUM CONCENTRATION (pg/I) 

Figure 9 Uptake in Blood Indicated by Model vs. Urinary Uranium 

Concentration, Class (D), Single Intake

8.11-20
102. I 1 ,••" I 1 

S101 

zA 

wA 

- Z 10 

RESULTS LEFT OF BAND REQUIRE NO ACTION. 

RESULTS WITHIN BAND REQUIRE ACTIONS 

(1) THRU (6), TABLE 5 

RESULTS RIGHT OF BAND REQUIRE ACTIONS 

(1) THRU (8), TABLE 5 

10"1 __ 1_ 1 _ 1 !1_ _11111_ 1 1 I I 111111 I I 1 111i 1

10-1 100 101 102 103 104 

URINARY URANIUM CONCENTRATION (pCi/I) 

Figure 10 Action Guide for Urinalysis Results Following Single 

Intake of Uranium, Chemical Toxicity
10.4 

-- I 1 0 

S =(0.4 + 0.38E + 0.0034E2 ) 10-6 

K 0 00 _ _ 

00 I

L) 0 Al DATA 

< 0 GULF DATA 

U.o IAEA SS NO. 6 

uli A ORO-651 EQUATIOF 

S10-6 

S (U-dep) 3.6 x 10-7 Ci/gm 

0 20 40 60 80 100 

WITHOUT U-235, E 

Figure 11 Specific Activity for Mixtures of U-238, U-234 and U-235

8.11-22
1I III I I 

... CLASS (Y) 

ol* o* 

102 4 

V RE 

-J 

I-U.. 

ACTIC 

15 reins =I MPDc TAL 

io 1 /2 < F 

101 0 .5 rtms - ACTI 0;- ...................... ...... . ........... !........... elm 

S-- __ 1/5<R 

UU ACTIO 

lo- 000 

S~REE 

10-1 

100 101 102 103 

URINARY URANIUM CONCENTRATION (pCi/l) 

Figure 12 Dose Conmmitment Indicated by Model vs. Urinary Uranium 

Concentration, Class (W) and (Y), Single Intake

8.11-23
1 0 2 1 R E S U L T >1 M P Oc 

00 10ACTIONS (1) THRU 11) 

15 em TABLE 4 oQ ......... ... .......... ... I......... 

0 1/2 e RESULT S1I MPD, 

2 1O, ACTIONS (11) THRU W( 

0= ... .............. ;• .. .......... .......... cc - 1/5 < RESULT S1 /2 MPO, 

LL -ACTIONS (1) T44RU 14) 

A; RESULT -1 /5 MPDC 

0 100 

Lkl ! NO ACTION 

0 

a 

10-2 1 1 1 .1 1 1 l 

100 101 102 103 

URANIUM FECAL EXCRETION RATE (pCi/DAY) 

Figure 13 Dose Commitment Indicated by Model vs. Uranium Fecal 

Excretion Rate, Class (W), Single Intake 

L

8.11-24

,C03.
102 

REI 

ACT 10 

TABLI 

0........................................a~* 000 0:ass.. ................. Noennn 

1 1/2< F 

10. _, ........ ......... s............u ,. ....................,.. ACTIC 

_ 

1/6< R 

ACTIO 

2 100 2 

0 

10-1 

100 101 102 103 

URANIUM FECAL EXCRETION RATE (pCi/DAY) 

Figure 14 Doss Commitment Indicated by Model Vs. Uranium Fecal 

Excretion Raft, Class (Y), Single Intake

8.11-25
104 S20 w/o U-235 

15-ein.1 PDCT" 

0 101 120 reins 35 IM A 

1/ 

tN y!yo (p U-235) 

Figure 15 Dose Commitment Indicated by Model vs. In Vivo 

Result, Cless (W), Single Intake

3. 11-26
104 

10

102

• oooe)mlm olao o mla e ao m 

20 w/o U-235A 

Is rams 1 MPD, 

7.5 rin 1 

.. ~ ....... ................. ag

RESULT •r1/5 MPD, 

NO ACTION

104

IN VIVO RESULT (pg U-235) 

,Figure 16 Don Commitment Indicated by Model vs. In Vivo 

Result, Class (Y), Single Intake

8.11-27

RESULT >1 MPOc 

ACTIONS (1) THRU 111) 

TABLE 4 

1/2- RESULTS!_I MPD¢ 

ACTIONS (1) THRU 68) 

1f5 <RESULTS1I2 MPO, 

ACTIONS (1) THRU (4)

0 

0 

0 

U. 

I

2)

102 

101

100 

10"1

101 103
A t 11

I.5 -

,/ -ii_

40 50 60

w/o U-235 

Figure 17 fmiichiment Scaling Factors for Model Dose Commitment 

Curves, In ViyD Measurement Following Single Exposure 

to Class (W| or Class (Y) Uranium Dust

90 100

711

0 

z

o0 

00J

1.2 

1.1 

1.0

U EU A

U ! I I I r I t

zu 30 70 80
- 10

'4 

0 

10-4 

z 

10

100 1011013 

TIME (DAYS AFTER INTAKE) 

Figure 18 Urinary Uranium Excretion Factors for Determining 

RD and Rw

8.11-29
LO) 

200 

100 - l 1 1 L 1 L L 1 I 

0 10 20 30 40 50 60 70 80 90 

w/o U-235 

FIGURE 19 Equilibrium Mass of U-235 in the Lung Equivalent to 1 Ma, n rrn

Permissible Lung Burden

100
102 1111 1 11I1!111 IuI I I I I 1 

101 

100 

0. 

w 

a. 

IL 

10-11 

101 102 103 104 

TIME AFTER BEGINNING OF EXPOSURE (DAYS) 

Figure 20 Model for Interpreting Urinalysis Results During Continuous 

Exposure to Constant Concentration of Uranium in Air

8,11-31