ORAU Team

Dose Reconstruction Project for NIOSH

Internal Dose Overestimates for Facilities With Air Sampling 

Programs

Document Number:

ORAUT-OTIB-0018

Effective Date: 03/18/2005

Revision No.: 00

Controlled Copy No.: ______

Page 1 of 27

Subject Experts: Elizabeth M. Brackett and Donald E. Bihl

Document Owner

Approval: Signature on File Date: 03/17/2005

Judson L. Kenoyer, Task 3 Manager

Concurrence: Signature on File Date: 03/17/2005

Richard E. Toohey, Project Director

Approval: Signature on File Date: 03/18/2005

James W. Neton, Associate Director for Science

Supersedes:

None
Effective Date: 03/18/2005 Revision No. 00 Document No. ORAUT-OTIB-0018 Page 2 of 27

RECORD OF ISSUE/REVISIONS

ISSUE 

AUTHORIZATION 

DATE

EFFECTIVE 

DATE

REV. 

NO. DESCRIPTION

Draft 11/23/2004 00-A New technical information bulletin to provide 

information for internal dose overestimates for 

facilities with air sampling programs. Initiated by 

Donald E. Bihl.

Draft 01/06/2005 00-B Incorporates internal review comments. Initiated 

by Donald E. Bihl.

Draft 03/10/2005 00-C Incorporates changes requested by NIOSH, 

including Attachments B and C. Updates RU 

contaminant levels. Eliminates discussion about 

ORAUT-OTIB-0002 related to ORAUT-OTIB0018. Initiated by Donald E. Bihl.

03/18/2005 03/18/2005 00 First approved issue. Initiated by Donald E. Bihl.
Effective Date: 03/18/2005 Revision No. 00 Document No. ORAUT-OTIB-0018 Page 3 of 27

1.0

The purpose of this technical information bulletin (TIB) is to provide an alternative method to that 

discussed in Technical Information Bulletin 002, Maximum Internal Dose Estimates for Certain DOE 

Complex Claims (ORAU 2004), for estimating intakes and internal doses when overestimated doses 

are acceptable. The internal doses estimated using this TIB will be smaller than those obtained using 

ORAU (2004) under some situations but are still overestimates. See Section 7.0 for additional 

discussion about when to use this TIB rather than ORAU (2004). 

PURPOSE

2.0

ORAU (2004) provides default overestimated intakes based on the assumption “that an intake 

resulting in 10% of a MPBB [maximum permissible body burden] would not have likely occurred to an 

unmonitored worker or would have likely resulted in a readily noticeable bioassay result in a 

monitored worker, readily noticeable air sample, or other indicators of personnel contamination.” 

ORAU (2004, Table 3.1.1-2) applies this assumption to each of a list of radionuclides to which 

workers at most U.S. Department of Energy (DOE)

BACKGROUND

1

For efficiency in processing claims, another method was needed to estimate intakes that are 

sites might have been exposed. The list includes 

three beta/gamma-emitting radionuclides and nine alpha-emitting radionuclides for nonreactor sites 

and an additional 16 beta/gamma-emitting radionuclides for sites with reactors. However, the ORAU 

(2004) method resulted in unrealistically high intakes of long-lived, long-retained radionuclides when 

the exposure time was only a few years; that is, the air concentrations would have had to have been 

unrealistically high for a worker to have incurred unnoticed intakes resulting in 10% of the MPBB. 

• Overestimates

• Derived from more realistic air concentrations

Most DOE sites had air sampling programs for particulate radioactive contamination and, with the 

exception of short-term, unplanned situations, controlled air concentrations to limiting values 

established by the National Council on Radiation Protection and Measurements (NCRP) or DOE. The 

first official national guidelines on air concentrations were produced by the NCRP and published in 

1953 in National Bureau of Standards (NBS) Handbook 52 (NBS 1953). The NCRP revised its 

methodology and expanded the list of covered radionuclides in 1959, published as NBS Handbook 69 

(NBS 1959). Both of these documents were based on and consistent with similar guidance from the 

International Commission on Radiological Protection (ICRP 1959). Subsequent to the publication of 

the NBS handbooks, DOE issued orders or regulations establishing air concentration limits applicable 

to its sites [for instance, in U.S. Atomic Energy Commission (AEC) Manual Chapter 0524 (AEC 1968) 

and DOE Order 5480.11 (DOE 1988)]. Since December 1993, 10 CFR Part 835 has established 

limits on air concentrations. Table 2-1 lists the history of workplace air concentration limits applicable 

at DOE sites for a number of important particulate radionuclides.

Most sites performed total alpha and total beta counting on air samples, using either a time delay or 

mathematical correction to account for radon progeny. Radionuclide identification was either not 

performed or was performed occasionally as a check on basic assumptions from knowledge of the 

facility source terms and processes. Trigger levels and prompt decisions for changing access to an 

area, usually by placing a “respiratory protection required” restriction for the area, were usually based 

on total alpha or total beta air concentrations. Because the radionuclide was not identified for every 

 1 In this document, reference to DOE includes its predecessor agencies.
Effective Date: 03/18/2005 Revision No. 00 Document No. ORAUT-OTIB-0018 Page 4 of 27

Table 2-1. Limiting air concentrations for selected particulates from 1953 to present. 

Radionuclidea

Limiting air concentration (μCi/mL)

NBS 1953 NBS 1959

AEC Manual 

Chapter 0524b

DOE Order 

5480.11c 10 CFR 835

Alpha emitters

Po-210 7E-11 2E-10 2E-10 3E-10 3E-10

Th-230 NLd 2E-12 2E-12 3E-12 3E-12

Th-232 NL 2E-12e 3E-11f 5E-13 5E-13

U natural sol 1.7E-11 7E-11 7E-11f NL NL

U natural insol 1.7E-11 6E-11 6E-11f NL NL

U-234 sol (D) NL 6E-10 6E-10 5E-10 5E-10

U-234 insol (Y) NL 1E-10 1E-10 2E-11 2E-11

U-238 sol (D) NL 7E-11 7E-11 6E-10 6E-10

U-238 insol (Y) NL 1E-10 1E-10 2E-11 2E-11

Np-237 NL 4E-12 4E-12 2E-12 2E-12

Pu-238 NL 2E-12 2E-12 3E-12 3E-12

Pu-239 2E-12 2E-12 2E-12 2E-12 2E-12

Am-241 3E-11 6E-12 6E-12 2E-12 2E-12

Cm-244 NL 9E-12 9E-12 4E-12 4E-12

Beta emitters

Mn-54 NL 4E-8 4E-8 3E-7 3E-7

Co-58 NL 5E-8 5E-8 3E-7 3E-7

Co-60 1E-6 9E-9 9E-9 1E-8 1E-8

Fe-59 6E-7 5E-8 5E-9 1E-7 1E-7

Zn-65 2E-6 6E-8 6E-8 1E-7 1E-7

Sr-90 2E-10 3E-10 1E-9 2E-9 2E-9

Y-91 4E-8 3E-8 3E-8 5E-8 5E-8

Nb-95 4E-7 1E-7 1E-7 5E-7 5E-7

Zr-95 NL 3E-8 3E-8 6E-8 6E-8

Tc-99 NL 6E-8 6E-8 3E-7 3E-7

Ru-103 NL 8E-8 8E-8 3E-7 3E-7

Ru-106 3E-8 6E-9 8E-8 5E-9 5E-9

Cs-134 NL 1E-8 1E-8 4E-8 4E-8

Cs-137 2E-7 1E-8 1E-8 7E-8 7E-8

Ba-140 6E-8 4E-8 4E-8 6E-7 6E-7

La-140 6E-8 1E-7 1E-7 5E-7 5E-7

Ce-141 NL 2E-7 2E-7 3E-7 2E-7

Ce-144 7E-9 6E-9 6E-9 6E-9 6E-9

Pm-147 2E-7 1E-7 6E-8 6E-8 6E-8

Eu-152 NL 3E-7 2E-8 1E-8 1E-8

Eu-154 6E-9 4E-9 7E-9 8E-9 8E-9

Eu-155 NL 7E-8 7E-8 4E-8 4E-8

a. Most limiting form (e.g., soluble, insoluble, inhalation class D,W,Y) is listed, with the exception of

uranium, for which the soluble form was based on chemical toxicity.

b. From 1968 version

c. From 1988 version (effective January 1989)

d. NL – not listed.

e. Printed as 2E-12 μCi/mL, but a footnote stated that continued use of 3E-11 μCi/mL was recommended 

until further investigation. 

f. Based on special definitions for the curie that added disintegrations from selected progeny. 

sample, the limit for the most restrictive, plausible radionuclide was often used to establish the trigger 

level. For facilities handling transuranics, the most restrictive air concentration for the alpha 

measurements was based on plutonium; for facilities with potential exposure to fission or activation 
Effective Date: 03/18/2005 Revision No. 00 Document No. ORAUT-OTIB-0018 Page 5 of 27

products, the most restrictive air concentration for beta measurements was based on 90Sr; at uranium 

facilities, the limits for uranium were generally used. 

3.0

3.1 APPLICABILITY

APPLICABILITY, LIMITATIONS, AND ASSUMPTIONS

This TIB applies to:

• Sites or facilities that rigorously sampled particulate air concentrations in areas of risk and 

controlled exposure to intakes according to the measured concentrations.

• Employment between 1953 and the present. (See first bullet in Section 3.2 for an exception.) 

• Claims for which it is likely that the covered employee had no significant intakes of particulate 

radioactive material. (See Section 7.0 for a discussion on insignificant intakes in the context of 

this TIB.)

• Intakes of particulate radioactive material only.

• All organs except respiratory tract organs for monitored workers and the thyroid; however, it 

can apply to the thyroid for uranium facilities or plutonium-only facilities (i.e., where there is no 

chance of exposure to radioiodines). 

3.2 LIMITATIONS

This TIB has the following limitations:

• It does not apply to employment prior to 1953; however, if the limiting air concentrations for the 

site of exposure are known for years prior to 1953, those concentrations can be used in the 

manner discussed in Sections 4.0 and 5.0. In addition, see Attachment A. It does not apply 

to Nevada Test Site outdoor exposures prior to 1963. 

• It applies only to particulate radioactive material. These particulate intakes are in addition to 

any intakes of 3

H, radioiodines, 14C, or radon/thoron and their progeny, as applicable.

• Intakes of particulate material with a documented particle-size distribution other than 5-μm 

activity median aerodynamic diameter (AMAD) must be checked to ensure that the dose to the 

organ of concern from this TIB is greater.

• If site-specific limiting air concentrations were greater than those listed in Section 3.3, those 

concentrations must be used. If the site-specific concentration was applicable to 

contamination for a given radionuclide only and exposure was limited to that radionuclide, the 

dose reconstructor can apply the intake to that radionuclide only. For instance, Mound had 

special limits for exposure to 210Po.

• It does not necessarily provide an overestimate to respiratory tract organs for monitored 

workers.
Effective Date: 03/18/2005 Revision No. 00 Document No. ORAUT-OTIB-0018 Page 6 of 27

• It does not provide an overestimate to the thyroid (regardless of monitoring), unless the worker 

was employed only at a uranium facility or a plutonium-only facility (i.e., where there is no 

chance of exposure to radioiodines).

3.3 ASSUMPTIONS

This TIB applies the following assumptions:

• All significant intake exposure was covered by an air sampling program, or the radiation 

protection program had a valid method to ensure that air concentrations did not exceed limits. 

(For instance, airborne contamination might have been controlled by controlling the inventory 

of radioactive material in an area and/or the physical form of the material.) 

• Chronic intakes were for 40 hours per week, or 2,000 hours per year, of particulate radioactive 

material with a 5-μm-AMAD particle-size distribution. 

• The breathing rate was 9.6 m3

/workday (ICRP 1994a) or 1.2 m3/hr averaged over an 8-hr day. 

• For sites or facilities with an exposure to alpha-emitting radionuclides that was principally 

transuranics, chronic exposure was at 2 × 10-12 μCi/mL. 

• For sites or facilities with an exposure to beta-emitting radionuclides, chronic exposure was at 

2 × 10-9 μCi/mL. 

• For sites or facilities with an exposure principally to uranium, chronic exposure was at 

6 × 10-10 μCi/mL. 

• Measured air sample concentrations were not always representative of the air concentration 

breathed. However, when applied to the long-term, 40-hour-per-week, chronic-intake 

assumption, it is assumed that the air sampling program was sufficient to prevent long-term 

intakes from exceeding the limiting air concentrations. See Section 6.0 for additional 

consideration of the possible nonrepresentativeness of air sampling. 

4.0

4.1 INTAKE QUANTITY

INHALATION INTAKE

The inhalation intake is determined by 

Intake = (air conc.)(breathing rate)(exposure period) (1)

From Equation 1, intakes in Bq/yr can be determined by 

Intake (Bq/yr) = (air conc. μCi/mL)(1.2 m3

/hr)(2,000 hr/yr)(106 mL/m3)(3.7 × 104 Bq/μCi)

or

Intake (Bq/yr) = (8.9 × 1013)(air conc. μCi/mL) (2)

where the air concentration is obtained from Table 4-1 or from site-specific limiting air concentrations 

(in μCi/mL) when applicable. 
Effective Date: 03/18/2005 Revision No. 00 Document No. ORAUT-OTIB-0018 Page 7 of 27

Table 4-1. Default limiting air concentrations

Exposure type

Air concentration 

(μCi/mL)

Associated daily 

intake (pCi)

Alpha-emitting radionuclides except for uranium facilities 

(includes Hanford from 1949, see Attachment A)

2E-12 13.2

Beta-emitting radionuclides except for uranium facilities 

(includes Hanford from 1949, see Attachment A)

2E-9 1.32E4

Uranium including recycled uranium (includes Hanford from 

1949, see Attachment A)

6E-10 3.96E3

ORNL alpha-emitting radionuclides except for uranium 

facilities, 1944-1952 

3E-11 1.98E2

ORNL beta-emitting radionuclides, 1944-1952 1E-7 6.60E5

Hanford alpha-emitting radionuclides except uranium facilities, 

1946-1949

4E-11 2.64E2

Hanford beta-emitting radionuclides, 1946-1949. 1E-8 6.60E4

Mound, 1952-71, Po-210 onlya NA 5.88E3

a. Mound had special urinalysis limits for Po-210. The doses associated with this intake will be larger than for general 

alpha-emitting radionuclides at 13.2 pCi/d for years of exposure but will be less for years after exposure ends. The dose 

reconstructor will have to run both cases and determine which option gives the largest total dose to the organ.

The intake per calendar day in pCi is

Intake (pCi/cal. d) = (air conc. μCi/mL)(1.2 m3

/hr)(2,000 hr/yr)(106 mL/m3)(106 pCi/μCi)/365 cal. d/yr

or

Intake (pCi/cal. d) = (6.6 × 1012)(air conc.) (3)

For most sites intakes will be assigned for alpha and beta intakes. Only the uranium intake should be 

assigned for facilities with exposure to only uranium (or natural thorium), with the exception of years 

when exposure was to recycled uranium. For recycled uranium, add intakes as listed in Table 4-2. 

Table 4-2. Intakes of contaminants in recycled 

uranium as fraction of uranium intake.

Radionuclide

Activity fraction of contaminant 

(e.g. pCi X/pCi U)

Pu-238 0.06

Np-237 0.005

Tc-99 0.4

Th-232 0.02

Ru-106 0.04

4.2 CHOICE OF RADIONUCLIDE

Because total alpha and total beta activity were measured on the air filters, the measurements 

represented all the particulate activity being breathed (as opposed to bioassay measurements that 

usually measure only certain radionuclides such that unmeasured radionuclides have to be accounted 

for in addition to the measured radionuclides). To be most accurate, the fractions of the total activity 

(alpha or beta) would have to be assigned to each radionuclide in the mixture in the air breathed. 

Those fractions were generally not determined on a regular basis and would have varied among sites, 

facilities, processes, or even specific work tasks. 
Effective Date: 03/18/2005 Revision No. 00 Document No. ORAUT-OTIB-0018 Page 8 of 27

Rather than estimating radionuclide fractions, this TIB overestimates the internal dose by assigning 

100% of the intake to the single radionuclide that produces the largest dose per unit intake to the 

organ of concern. In addition, organ dose depends on the absorption type of the radionuclides. The 

radionuclide and absorption type combination that produces this “largest dose” can differ by organ, 

time of exposure, and time after end of exposure. Because the annual organ dose is the dose of 

interest, and the annual dose varies from year to year for a given radionuclide, the largest dose 

contributor could change over the years. For example, for a 10-year chronic intake of beta emitters, 

134Cs type F delivers the largest dose to the urinary bladder during years 1 through 10. However, if 

the date of diagnosis is sometime after the intake period, the assumption of a 106Ru type F intake 

during the 10 years of exposure yields the largest dose for years 11 through 14, as does 90Sr type F 

for all subsequent years. Rather than determining which radionuclide and absorption type 

combination produces the largest dose, an additional claimant-favorable assumption was made. 

Each year between the start of exposure and date of diagnosis is evaluated individually and the 

largest dose is assigned. For the previous example, it would be assumed that the intake was 

comprised of 100% type F 134Cs when assigning years 1 through 10. For years 11 through 14, it 

would be assumed that the intake had been entirely made up of type F 106Ru, and that it was 90Sr for 

years 15 through 65.

Table 4-3 lists the inventory of radionuclides and absorption types from which the combination 

producing the largest dose can be obtained. This is the default list at present. 

Table 4-3. Inventory of radionuclides and absorption types.

Radionuclides/absorption types 

associated with the alpha choice

Am-241 M, S Pu-240 M, S

Cf-252 M Pu-242 M, S

Cm-244 M Ra-226 M

Np-237 M Th-228 M, S

Po-210 F, M Th-230 M, S

Pu-238 M, S Th-232 M, S

Pu-239 M, S RUa F, M, S

Radionuclides/absorption types associated with the beta 

choice

Ag-110 M, S Fe-59 F, M S-35 F, M

Ba-140 F Hf-181 F, M Sb-125 F, M

Ce-141 M, S La-140 F, M Sc-46 S

Ce-144 M, S Mn-54 F, M Sn-113 F, M

Co-58 M, S Mo-99 F, S Sr-89 F

Co-60 M, S Na-24 F Sr-90 F 

Cr-51 F, M, S Nb-95 M Tb-160 M

Cs-134 F Ni-63 F, M Tc-99 M

Cs-137 F P-32 F, M Y-91 M, S

Eu-152 M Pm-147 M, S Zn-65 S

Eu-154 M Ru-103 F, M, S Zr-95 F,M,S

Eu-155 M Ru-106 F, M, S

Radionuclides/absorption types associated 

with the uranium choice

Th-232 M, S RU F, M, S

a. RU = U-234 plus the contaminants from Table 4-

2 in the ratios provided in Table 4-2.
Effective Date: 03/18/2005 Revision No. 00 Document No. ORAUT-OTIB-0018 Page 9 of 27

Notes: Ac-227 is a progeny of 231Pa in the 235U decay chain. It was probably not present in significant 

quantities unless 231Pa or 227Ac was purposely concentrated; therefore, it was not included in the 

default list for the alpha choice. It should be added to the list if 231Pa or 227Ac was handled in a pure or 

concentrated form at the site in question. 

Th-232 is included in the uranium list because many uranium facilities also processed thorium at 

some time. Th-232 can be removed from the list if it is known for sure that the facility did not handle 

thorium. Removal of 232Th will reduce dose from 2 to 700 times depending on organ and length of 

exposure.

For strontium, type S is applicable to the titanate form only and is unlikely to be present at most sites.

Type S was not included in the default list for the beta choice. If it is established that a site had 

strontium titanate, type S strontium will have to be added to the list. Check the Site Profile for 

applicability. Adding type S strontium will significantly increase the dose for some organs. 

5.0

The possibility of ingestion intakes has to be considered separately from inhalation intakes when 

intake is not based on bioassay measurements. Estimation of Ingestion Intakes (OCAS 2004) 

provides the method for estimating ingestion intakes based on air concentrations:

INGESTION INTAKE

Ingestion intake = 0.2 (inhalation intake) (4)

These intakes would be applied to the same years for which inhalation intakes occurred, using the 

same radionuclide. Use the f1 associated with the absorption type from Annex F in ICRP Publication 

68 (ICRP 1994b). 

6.0

Assuming an intake at the limiting air concentration for every minute of employment is probably an 

overestimate. However, there are sources of uncertainty. For instance, 

DOSE DISTRIBUTION

• The air sample results might not have been representative of the air breathed. If a worker was 

close to a localized source, the air concentration the worker breathed might have been higher 

than the air collected by a sampler several to tens of feet away. Offsetting this problem 

somewhat is the likelihood that the worker breathed larger particles than the air sampler 

collected. The time spent near a localized source would have been less than full time.

• Enforcement of the limiting air concentrations at some facilities for some periods might have 

been lax.

• Prior to widespread use of alarming continuous air monitors (CAMs), exposure to air 

concentrations above limiting air concentrations for periods of days to a few weeks was 

possible. For instance, a filter exchanged weekly with delayed counting for radon decay could 

easily result in a 2-week lag between the change in air concentration and change in access 

control. Even with the use of CAMs, radon progeny interference was a problem with alpha 

monitoring in many facilities such that immediate recognition of an air concentration slightly 

greater than the plutonium limit was difficult. 

• For beta emitters, the counting efficiency for converting counts to total activity is dependent on 

the beta energy. If the beta energy of the radionuclide on the filter is less than the beta energy 
Effective Date: 03/18/2005 Revision No. 00 Document No. ORAUT-OTIB-0018 Page 10 of 27

of the calibration source, the total activity would have been underestimated. This is offset 

somewhat by the generally lower dose per unit intake from the lower energy beta emitters. 

For alpha emitters, self-absorption of the alphas due to high dust loading might not have been 

compensated for. 

• The volume of air sampled might not have been measured accurately; for instance, it was 

common to use flow rate meters and the average of the on/off flow rate to estimate the volume 

of air rather than using total air volume meters.

• Operational logistics might have temporarily compromised the air sampling in some areas, 

such as pump failures, leaking filters, filters destroyed by harsh chemicals, or filters obviously 

contaminated by a source other than the air. 

These problems arguably could have enabled intakes exceeding the air concentration limits for some 

periods. Because of the sensitivity to these uncertainties of the method used in this TIB to determine 

dose, the dose uncertainty distribution is lognormal with the geometric mean as determined by 

the equations in this document with a geometric standard deviation of 3.

Remember that exposure to tritium, radioiodines, radon, or 14C has to be accounted for separately 

from these intake/dose estimations. 

7.0

Dose reconstructors should use this TIB for workers who were not on a bioassay program or were 

monitored but had no indication of intakes in the bioassay data, except as discussed below and 

subject to the limitations in Section 3.0. 

WHEN TO USE THIS TIB

Some bioassay methods were capable of detecting small intakes, well below the intakes determined 

using this TIB. Whole-body counting for gamma emitters with high gamma abundance and energies 

greater than about 200 keV is a good example. Use of this TIB is still an overestimate even if there 

are bioassay indications of intakes (i.e., bioassay results exceeding the decision level, minimum 

detection level, or recording level, as appropriate), provided the results meet the conditions listed in 

Table 7-1. The values in Table 7-1 are actually a factor of 10 less than that which would equal the 

dose produced by the assumed intake to account for uncertainties in counting, the possibility of 

several radionuclides in a single count, undetected radionuclides, and the different impacts between 

inhaled or ingested material. 

Urinalysis results from the intakes listed in this TIB can be predicted using the current ICRP models. 

If an individual has urinalysis results that are less than 0.1 times that predicted by the intakes of this 

TIB using the most favorable absorption type, the TIB intake can be considered an overestimate.
Effective Date: 03/18/2005 Revision No. 00 Document No. ORAUT-OTIB-0018 Page 11 of 27

Table 7-1. Whole-body count (WBC) results below which this TIB method is still considered an 

overestimate.

Radionuclide Absorption type

Time since last 

WBC (d)a Organ of concern

WBC result must be less 

than (nCi):

Cs-137 F 90 Adrenals 34

Urinary bladder 30

Brain 28

Breast 27

Gall bladder 58

Heart wall 31

Kidneys 31

Liver 150

Muscle 30

Ovaries 32

Pancreas 32

Testes 29

Thyroid 30

Red bone marrow 115

Bone surface 220

Stomach 30

SI 31

ULI 52

LLI 130

Skin 26

Spleen 31

Thymus 30

Uterus 32

ET 69

Lung 640

Colon 87

Esophagus 30

Cs-137 F 180 Adrenals 39

Urinary bladder 34

Brain 32

Breast 30

Gall bladder 66

Heart wall 35

Kidneys 35

Liver 170

Muscle 33

Ovaries 36

Pancreas 36

Testes 33

Thyroid 34

Red bone marrow 130

Bone surface 250

Stomach 34

SI 36

ULI 58

LLI 140

Skin 29

Spleen 35

Thymus 34

Uterus 36

ET 78

Lung 720

Colon 98

Esophagus 34
Effective Date: 03/18/2005 Revision No. 00 Document No. ORAUT-OTIB-0018 Page 12 of 27

Table 7-1 (Continued). Whole-body count (WBC) results below which this TIB method is still 

considered an overestimate.

Radionuclide Absorption type

Time since last 

WBC (d)a Organ of concern

WBC result must be less 

than (nCi):

Cs-137 F 365 Adrenals 24

Urinary bladder 21

Brain 19

Breast 19

Gall bladder 16

Heart wall 22

Kidneys 21

Liver 106

Muscle 21

Ovaries 22

Pancreas 22

Testes 20

Thyroid 21

Red bone marrow 80

Bone surface 150

Stomach 21

SI 22

ULI 36

LLI 89

Skin 18

Spleen 21

Thymus 21

Uterus 22

ET 48

Lung 440

Colon 60

Esophagus 21

Cs-137 F 730 Adrenals 2

Urinary bladder 2

Brain 2

Breast 2

Gall bladder 4

Heart wall 2

Kidneys 2

Liver 10

Muscle 2

Ovaries 2

Pancreas 2

Testes 2

Thyroid 2

Red bone marrow 8

Bone surface 15

Stomach 2

SI 2

ULI 4

LLI 9

Skin 2

Spleen 2

Thymus 2

Uterus 2

ET 5

Lung 43

Colon 6

Esophagus 2
Effective Date: 03/18/2005 Revision No. 00 Document No. ORAUT-OTIB-0018 Page 13 of 27

Table 7-1 (Continued). Whole-body count (WBC) results below which this TIB method is still 

considered an overestimate.

Radionuclide Absorption type

Time since last 

WBC (d)a Organ of concern

WBC result must be less 

than (nCi):

Co-60 M or S 90 Adrenals 10

Urinary bladder 21

Brain 25

Breast 5

Gall bladder 23

Heart wall 4

Kidneys 15

Liver 36

Muscle 13

Ovaries 14

Pancreas 11

Testes 28

Thyroid 15

Red bone marrow 43

Bone surface 108

Stomach 11

SI 13

ULI 15

LLI 25

Skin 16

Spleen 9

Thymus 6

Uterus 20

ET 4

Lung 11

Colon 20

Esophagus 6

Co-60 M or S 180 Adrenals 12

Urinary bladder 27

Brain 31

Breast 8

Gall bladder 30

Heart wall 7

Kidneys 19

Liver 45

Muscle 17

Ovaries 18

Pancreas 14

Testes 35

Thyroid 19

Red bone marrow 51

Bone surface 135

Stomach 14

SI 17

ULI 18

LLI 31

Skin 29

Spleen 14

Thymus 9

Uterus 25

ET 6

Lung 19

Colon 25

Esophagus 9
Effective Date: 03/18/2005 Revision No. 00 Document No. ORAUT-OTIB-0018 Page 14 of 27

Table 7-1 (Continued). Whole-body count (WBC) results below which this TIB method is still 

considered an overestimate.

Radionuclide Absorption type

Time since last 

WBC (d)a Organ of concern

WBC result must be less 

than (nCi)

Co-60 M or S 360 Adrenals 13

Urinary bladder 28

Brain 32

Breast 9

Gall bladder 30

Heart wall 8

Kidneys 19

Liver 46

Muscle 17

Ovaries 18

Pancreas 15

Testes 36

Thyroid 19

Red bone marrow 60

Bone surface 139

Stomach 15

SI 17

ULI 19

LLI 32

Skin 21

Spleen 14

Thymus 10

Uterus 26

ET 5

Lung 20

Colon 26

Esophagus 10

Co-60 M or S 730 Adrenals 6

Urinary bladder 13

Brain 14

Breast 4

Gall bladder 14

Heart wall 4

Kidneys 9

Liver 21

Muscle 8

Ovaries 8

Pancreas 7

Testes 17

Thyroid 570

Red bone marrow 27

Bone surface 63

Stomach 7

SI 8

ULI 9

LLI 15

Skin 10

Spleen 7

Thymus 4

Uterus 12

ET 2

Lung 9

Colon 12

Esophagus 4
Effective Date: 03/18/2005 Revision No. 00 Document No. ORAUT-OTIB-0018 Page 15 of 27

Table 7-1 (Continued). Whole-body count (WBC) results below which this TIB method is still 

considered an overestimate.

Radionuclide Absorption type

Time since last 

WBC (d)a Organ of concern

WBC result must be less 

than (nCi):

Mn-54 F or M 90 Adrenals 24

Urinary bladder 49

Brain 42

Breast 23

Gall bladder 35

Heart wall 20

Kidneys 29

Liver 47

Muscle 40

Ovaries 31

Pancreas 30

Testes 65

Thyroid 51

Red bone marrow 70

Bone surface 113

Stomach 39

SI 42

ULI 43

LLI 100

Skin 47

Spleen 39

Thymus 26

Uterus 43

ET 15

Lung 150

Colon 71

Esophagus 26

Mn-54 F or M 180 Adrenals 8

Urinary bladder 17

Brain 14

Breast 16

Gall bladder 12

Heart wall 13

Kidneys 10

Liver 16

Muscle 14

Ovaries 11

Pancreas 10

Testes 22

Thyroid 18

Red bone marrow 24

Bone surface 39

Stomach 14

SI 11

ULI 15

LLI 35

Skin 16

Spleen 16

Thymus 17

Uterus 15

ET 6

Lung 117

Colon 24

Esophagus 17
Effective Date: 03/18/2005 Revision No. 00 Document No. ORAUT-OTIB-0018 Page 16 of 27

Table 7-1 (Continued). Whole-body count (WBC) results below which this TIB method is still 

considered an overestimate.

Radionuclide Absorption type

Time since last 

WBC (d)a Organ of concern

WBC result must be less 

than (nCi):

Mn-54 F or M 365 Adrenals 0.5

Urinary bladder 0.9

Brain 0.8

Breast 0.9

Gall bladder 0.6

Heart wall 0.7

Kidneys 0.5

Liver 0.9

Muscle 0.7

Ovaries 0.6

Pancreas 0.6

Testes 1.2

Thyroid 1.0

Red bone marrow 1.3

Bone surface 2.1

Stomach 0.7

SI 0.6

ULI 0.8

LLI 1.9

Skin 0.9

Spleen 0.9

Thymus 0.9

Uterus 0.8

ET 0.3

Lung 14

Colon 1.3

Esophagus 0.9

Mn-54 F or M 730 Not applicable for all organs

Nb-95 M or S 90 Adrenals 18

Urinary bladder 34

Brain 50

Breast 13

Gall bladder 35

Heart wall 11

Kidneys 16

Liver 53

Muscle 24

Ovaries 14

Pancreas 21

Testes 65

Thyroid 33

Red bone marrow 57

Bone surface 51

Stomach 18

SI 13

ULI 11

LLI 15

Skin 34

Spleen 22

Thymus 14

Uterus 27

ET 3

Lung 12

Colon 13

Esophagus 14
Effective Date: 03/18/2005 Revision No. 00 Document No. ORAUT-OTIB-0018 Page 17 of 27

Table 7-1 (Continued). Whole-body count (WBC) results below which this TIB method is still 

considered an overestimate.

Radionuclide Absorption type

Time since last 

WBC (d)a Organ of concern

WBC result must be less 

than (nCi):

Nb-95 M or S 180 Adrenals 4

Urinary bladder 8

Brain 12

Breast 4

Gall bladder 8

Heart wall 3

Kidneys 4

Liver 13

Muscle 6

Ovaries 3

Pancreas 5

Testes 16

Thyroid 8

Red bone marrow 14

Bone surface 12

Stomach 4

SI 3

ULI 3

LLI 4

Skin 8

Spleen 5

Thymus 4

Uterus 7

ET 1

Lung 3

Colon 3

Esophagus 4

Nb-95 M or S 365 Adrenals 0.1

Urinary bladder 0.2

Brain 0.3

Breast 0.1

Gall bladder 0.2

Heart wall 0.1

Kidneys 0.1

Liver 0.3

Muscle 0.2

Ovaries 0.1

Pancreas 0.1

Testes 0.4

Thyroid 0.2

Red bone marrow 0.4

Bone surface 0.3

Stomach 0.1

SI 0.1

ULI 0.1

LLI 0.1

Skin 0.2

Spleen 0.1

Thymus 0.1

Uterus 0.2

ET 0.0

Lung 0.1

Colon 0.1

Esophagus 0.1

Nb-95 M or S 730 Not applicable for all organs
Effective Date: 03/18/2005 Revision No. 00 Document No. ORAUT-OTIB-0018 Page 18 of 27

Table 7-1 (Continued). Whole-body count (WBC) results below which this TIB method is still 

considered an overestimate.

Radionuclide Absorption type

Time since last 

WBC (d)a Organ of concern

WBC result must be less 

than (nCi):

Ce-141 M or S 90 Adrenals 130

Urinary bladder 240

Brain 270

Breast 106

Gall bladder 180

Heart wall 79

Kidneys 170

Liver 29

Muscle 180

Ovaries 107

Pancreas 140

Testes 320

Thyroid 240

Red bone marrow 104

Bone surface 20

Stomach 37

SI 18

ULI 6

LLI 6

Skin 200

Spleen 180

Thymus 108

Uterus 200

ET 3

Lung 4

Colon 6

Esophagus 108

Ce-141 M or S 180 Adrenals 36

Urinary bladder 65

Brain 74

Breast 27

Gall bladder 50

Heart wall 20

Kidneys 46

Liver 8

Muscle 48

Ovaries 27

Pancreas 39

Testes 89

Thyroid 67

Red bone marrow 29

Bone surface 6

Stomach 9

SI 5

ULI 1.4

LLI 1.5

Skin 57

Spleen 45

Thymus 27

Uterus 57

ET 0.8

Lung 0.9

Colon 1.4

Esophagus 27
Effective Date: 03/18/2005 Revision No. 00 Document No. ORAUT-OTIB-0018 Page 19 of 27

Table 7-1 (Continued). Whole-body count (WBC) results below which this TIB method is still 

considered an overestimate.

Radionuclide Absorption type

Time since last 

WBC (d)a Organ of concern

WBC result must be less 

than (nCi):

Ce-141 M or S 365 Adrenals 1.3

Urinary bladder 2.4

Brain 2.7

Breast 0.9

Gall bladder 1.8

Heart wall 0.7

Kidneys 1.7

Liver 0.3

Muscle 1.7

Ovaries 0.9

Pancreas 1.4

Testes 3.3

Thyroid 2.4

Red bone marrow 1.1

Bone surface 0.2

Stomach 0.3

SI 0.2

ULI <0.1

LLI <0.1

Skin 2.1

Spleen 1.5

Thymus 0.9

Uterus 2.0

ET <010

Lung <0.1

Colon <0.1

Esophagus 0.9

Ce-144 M or S 90 Adrenals 56

Urinary bladder 59

Brain 46

Breast 40

Gall bladder 89

Heart wall 52

Kidneys 53

Liver 3

Muscle 49

Ovaries 60

Pancreas 56

Testes 52

Thyroid 54

Red bone marrow 13

Bone surface 15

Stomach 30

SI 15

ULI 4

LLI 4

Skin 38

Spleen 55

Thymus 52

Uterus 63

ET 5

Lung 3

Colon 4

Esophagus 52
Effective Date: 03/18/2005 Revision No. 00 Document No. ORAUT-OTIB-0018 Page 20 of 27

Table 7-1 (Continued). Whole-body count (WBC) results below which this TIB method is still 

considered an overestimate.

Radionuclide Absorption type

Time since last 

WBC (d)a Organ of concern

WBC result must be less 

than (nCi):

Ce-144 M or S 180 Adrenals 86

Urinary bladder 90

Brain 69

Breast 60

Gall bladder 136

Heart wall 79

Kidneys 80

Liver 5

Muscle 75

Ovaries 91

Pancreas 86

Testes 78

Thyroid 82

Red bone marrow 20

Bone surface 22

Stomach 46

SI 20

ULI 6

LLI 5

Skin 58

Spleen 83

Thymus 78

Uterus 95

ET 6

Lung 4

Colon 5

Esophagus 78

Ce-144 M or S 365 Adrenals 103

Urinary bladder 108

Brain 84

Breast 72

Gall bladder 160

Heart wall 96

Kidneys 97

Liver 6

Muscle 90

Ovaries 110

Pancreas 103

Testes 95

Thyroid 99

Red bone marrow 24

Bone surface 27

Stomach 53

SI 22

ULI 6

LLI 6

Skin 70

Spleen 100

Thymus 95

Uterus 110

ET 7

Lung 4

Colon 6

Esophagus 95

a. ±15%. The choice of days is meant to represent general measurement frequencies, such as quarterly, semiannually, or annually. It is 

recognized that workers did not get whole-body counts at intervals that were exact to the day. 
Effective Date: 03/18/2005 Revision No. 00 Document No. ORAUT-OTIB-0018 Page 21 of 27

REFERENCES

AEC (U.S. Atomic Energy Commission), 1968, Manual, Chapter 0524, “Standards for Radiation 

Protection,” AEC 0524-01, November 8.

DOE (U.S. Department of Energy), 1988, “Radiation Protection for Occupational Workers,” Order 

5480.11, Washington D.C., December 21.

ICRP (International Commission on Radiological Protection), 1959, Report of Committee II on 

Permissible Dose for Internal Radiation, Publication 2, Pergamon Press, London. 

ICRP (International Commission on Radiological Protection), 1994a, Human Respiratory Tract Model 

for Radiological Protection, Publication 66, Pergamon Press, London.

ICRP (International Commission on Radiological Protection), 1994b, Dose Coefficients for Intakes of 

Radionuclides by Workers, Publication 68, Pergamon Press, London.

NBS (National Bureau of Standards), 1953, Maximum Permissible Amounts of Radioisotopes in the 

Human Body and Maximum Permissible Concentrations in Air and Water, NBS Handbook 52 

(also referred to as NCRP Publication 11), Washington, D.C.

NBS (National Bureau of Standards), 1959, Maximum Permissible Body Burdens and Maximum 

Permissible Concentrations in Air and Water for Occupational Exposure, NBS Handbook 69 

(also referred to as NCRP Publication 22), Washington, D.C.

Office of Compensation Analysis and Support, OCAS-TIB-009, Technical Information Bulletin: 

Estimation of Ingestion Intakes, Rev 0, April 13, 2004.

ORAU (Oak Ridge Associated Universities), 2004, Technical Information Bulletin — Maximum Internal 

Dose Estimates for Certain DOE Complex Claims, ORAUT-OTIB-0002, Rev. 1, Oak Ridge, 

Tennessee. 
Effective Date: 03/18/2005 Revision No. 00 Document No. ORAUT-OTIB-0018 Page 22 of 27

ATTACHMENT A

AIR CONCENTRATION LIMITS PRIOR TO 1953

Air concentration limits established for a site prior to 1953 can be used to extend the applicability of 

this TIB to those earlier years. 

Because Hanford Site tolerance levels were used to control intakes, they fit the criteria of air 

concentration limit. The alpha and beta particular air concentration limit at Hanford from at least 1949 

to 1952 were 1 × 10-12 μCi/mL for alpha in nonuranium facilities, 1 × 10-9 μCi/mL for beta, and 1.5 × 

10-4 μg U/mL (which converts to 1.1 × 10-10 μCi/mL) for uranium facilities (Patterson 1949). These 

concentrations are less than the concentrations listed in Table 4-1; thus, the use of Table 4-1 values 

is a plausible overestimate. Therefore, this TIB approach can be used unmodified for Hanford claims 

from 1949 to the present. Higher tolerance levels of 1 × 10-8 μCi/mL for beta-emitters and 4 × 10-11

μCi/mL for plutonium were in place at least by October 1945 (Cantril 1945).

Oak Ridge National Laboratory (ORNL) used the concept of tolerance levels for air concentrations 

prior to 1953. By July 1944, ORNL had established an air concentration limit of 5 × 10-10 μg/mL 

(3 × 10-11 μCi/mL) for plutonium based on alpha counting (Parker 1944a). A limit for beta-emitters in 

air (based on tolerance in the thyroid for 131I even though they might not have been collecting iodine 

properly on their filters) was established at least by 1944 at 1 × 10-7 μCi/mL (Parker 1944b). 

REFERENCES

Cantril, S. T., 1945, “Tolerance Limits,” Letter to file, HW 4.159 or 7-2602, Hanford Works, Richland, 

Washington, October 18.

Parker, H. M., 1944a, “Product Concentration in the Air,” Memo to I. Perlman, ORNL CF 44-7-78, 

Clinton Laboratories, Oak Ridge, Tennessee, July 1. 

Parker, H. M., 1944b, Review of Air Monitoring Procedures at Clinton Laboratories, CH-2562, Clinton 

Laboratories, Oak Ridge, Tennessee. 

Patterson, C. M., 1949, “General Operating Tolerances,” Letter to Lauriston S. Taylor (National 

Bureau of Standards), HW-12710, Hanford Works, Richland, Washington, March 11. 
Effective Date: 03/18/2005 Revision No. 00 Document No. ORAUT-OTIB-0018 Page 23 of 27

ATTACHMENT B

VALIDATION OF THE BASIC ASSUMPTION IN THIS TIB

The basis for this TIB is that weapons sites with a radiological control program controlled exposures to 

airborne radioactive contaminates to less than an applicable limit. The limit varied with time and 

isotope of concern. This TIB acknowledges that exposures to concentrations greater than these limits 

did occur. However, the assumption is that, when integrated over time, the average exposure to any 

individual was less than that which would occur if someone were exposed to the limit continuously. 

The assumption is tested in the following analysis. Note that this analysis does not change the 

assumption but merely tests the validity of it.

B.1 URANIUM

Uranium urinalysis data from the Y-12 site was used to test the validity of the assumption. The Y-12 

site processed uranium extensively. The data consisted of hundreds of urine samples each month 

from 1952 through 1985. Because this TIB provides mean values that are to be used in a lognormal 

distribution, the median result was used in the comparison. Figure B-1 plots these median sample 

results as well as the uranium result predicted by this TIB for an inhalation of type M uranium.

Figure B-1. Y-12 versus OTIB-18 uranium (type M).

The TIB result is considerably higher than the actual Y-12 median urine sample result. The 2-year 

result begins 1 month after the start of the chronic intake and is approximately 10 times higher than 

the highest actual median result. This verifies that for Y-12 uranium intakes, either the assumed 

intake is an overestimate or the lung absorption of the uranium is considerably slower than type M. 

Figure B-2 shows the same information using an absorption type S assumption for the TIB values. 

This graph indicates that for a long-term exposure, it can be shown that this TIB overestimates actual 

results even if absorption type S is assumed. The short-term exposure, on the other hand, indicates 

that it could take as long as 3 years to reach the level of the highest median urinalysis result. This 

implies that this TIB approach might not be an overestimate for type S exposures of duration that are 

less than 3 years.
Effective Date: 03/18/2005 Revision No. 00 Document No. ORAUT-OTIB-0018 Page 24 of 27

Figure B-2. Y-12 versus OTIB-18 uranium (type S).

B.2 PLUTONIUM

The Rocky Flats Plant worked extensively with plutonium. Plutonium urine samples from Rocky Flats 

were evaluated from 1953 through 1969. For every year, the median sample was recorded as zero. 

The lowest recorded positive value varied through the years from 0.02 dpm/day (0.009 pCi/day) to 

0.09 dpm/day (0.04 pCi/day) with most years at 0.02 dpm/day. Figure B-3 shows the assumed intake 

in this TIB for both a type S and a type M inhalation. The figure also shows the 0.009-pCi/day and the 

0.04-pCi/day values. The figure indicates that the TIB values would be likely to exceed the measured 

data soon after the start of a chronic type M inhalation. The type S inhalation, however, might not 

result in detectable urine samples.

Figure B-3. Rocky Flats Pu expected urine versus actual results.

The Hanford site produced much of the plutonium used by the weapons program. It appears to be 

reasonable, therefore, to review Hanford site plutonium urine results against the assumptions in this 

TIB. 

The TIB analysis evaluated plutonium urine samples from Hanford from 1953 through 1969. The 

median sample for each year varied. The median result was never more than 0.023 pCi/day and for 
Effective Date: 03/18/2005 Revision No. 00 Document No. ORAUT-OTIB-0018 Page 25 of 27

most years was less than that. Figure B-4 shows the assumed intake in this TIB for both a type S and 

a type M inhalation. The figure also shows the 0.023-pCi/day value. As with the Rocky Flats data, 

the graph indicates that the TIB values would be likely to exceed the measured data soon after the 

start of a chronic type M inhalation but a type S inhalation might not result in a detectable urine 

sample.

Figure B-4. Hanford Pu expected urine versus actual results.

B.3 FISSION PRODUCTS

The fission product that was primarily sampled in urine at Hanford was 90Sr. In the 1960s, the 

recording limit at Hanford for 90Sr urine samples appears to be 16.7 pCi/day. More than 95% of the 

samples in 1966, 1967, and 1968 were recorded as less than this limit. After that period, the 

recording limit decreased and enabled the evaluation of the median sample result.

Figure B-5 shows the median and 95th-percentile urine result predicted from the values used in this 

TIB for a chronic inhalation of type F 90Sr. The 95th-percentile results were determined using the 

assumption in this TIB that the intakes are lognormally distributed with a geometric standard deviation 

of three. The figure also shows the recording limit of 16.7 pCi/day as well as the median sample 

results for 1970 through 1974.

Figure B-5 indicates that the results predicted from the 95th percentile of the intake in this TIB exceed 

the reporting limit from the 1960s. More than 95% of the values were reported as less than this value. 

In addition, it shows that when the reporting limit was reduced, the median result was less than the 

mean result predicted from the intake in this TIB.

B.4 CONCLUSION

The analysis discussed above indicates that the assumption made in this TIB is valid if the material to 

which an individual is exposed has type F or type M absorption characteristics. Because these are 

the limiting absorption types for systemic organs, it appears the assumption is valid for systemic 

organs.
Effective Date: 03/18/2005 Revision No. 00 Document No. ORAUT-OTIB-0018 Page 26 of 27

Figure B-5. Hanford Sr-90 expected urine versus actual results.

Type S, however, is the limiting absorption type (when comparing the same intake values for different 

absorption types) for the respiratory tract. Due to the detection limits of urinalysis, it cannot be shown 

that the values of this TIB are an overestimate for the respiratory tract. However, there are several 

important issues to point out. 

1. While comparing the recording limit to the TIB mean cannot show the TIB to be an 

overestimate, continuous exposures at these levels would be reportable in many of the longterm workers. Levels below the reporting limit were seen in a large percent of the sampled 

population, much larger than 50%.

2. Long-term exposure to these levels requires that an employee would be working into the 

modern era. In more modern eras, chest counts, whole-body counts, and more sensitive 

urinalysis would indicate if the average worker were exposed to these levels for a long 

duration.

3. The data analyzed was obviously for monitored workers. The monitored population is 

probably the population that radiological control personnel believed to have the highest 

exposure potential.

Taken together, this implies that while it might not be possible to demonstrate that the average 

radiological worker was exposed to a lower concentration of type S material, it can be seen that it is

very possible. Therefore this TIB should not be considered an overestimate for respiratory tract dose 

unless other information, such as chest counts or whole-body counts, is available for the individual.

However, the TIB assumes a continuous exposure every working minute of every day. For individuals 

who were only intermittently exposed, a considerably higher air concentration would have had to be 

routinely present to equal the same intake. Intakes considerably higher than those listed in this TIB 

would have been detectable in the urine results of those present more frequently in those areas. This 

TIB should, therefore, be considered an overestimate for intermittently exposed workers regardless of 

the organ of concern.
Effective Date: 03/18/2005 Revision No. 00 Document No. ORAUT-OTIB-0018 Page 27 of 27

ATTACHMENT C

SITE APPLICABILITY

This TIB is applicable to all DOE sites with the limitations listed in the TIB and exceptions listed below. 

Table 4-3 contains three inventory lists of radionuclides. Dose reconstructors should use these lists 

as follows:

• The alpha list should apply alone to sites or facilities that primarily handled plutonium.

• The uranium list should be applied alone to sites or facilities that primarily handled uranium.

• The alpha plus the beta list should be applied to reactor sites, national laboratories, and any 

other sites.

Some large sites contained facilities that performed different functions. For example, the Hanford Site 

is a reactor site but also had fuel fabrication facilities. The fabrication facilities normally controlled air 

concentrations to uranium limits. Therefore, the uranium list should be applied to individuals working 

in those facilities.

Some sites operated with particular nuclides in campaigns. Once the campaign ended, the nuclide 

was no longer routinely handled. For example, the Fernald site produced thorium products during 

several campaigns but did not routinely handle it between these campaigns. Therefore, it is 

permissible to remove thorium from the list of possible radionuclides during times when the individual 

was not exposed to thorium. This can be done in other situations when there is clear evidence that 

the individual was not exposed to a particular radionuclide.

Exception

Until 1962, the Nevada Test Site performed atmospheric testing of nuclear weapons. These tests had 

the potential to create high airborne concentrations for relatively short periods. While it is possible 

that the continuous assumption made in this TIB will overestimate these intermittent exposures, 

further evaluation is necessary to verify this. Therefore, this TIB is not currently applicable to 

exposures at the Nevada Test Site prior to 1963.