Adventures in Dose Reconstruction
Lynn R. Anspaugh, Ph.D.
Research Professor of Radiobiology
Radiology Department, School of Medicine
University of Utah, Salt Lake City
Presentation to the
Community Environmental Monitoring Workshop
Brian Head, Utah
July 26, 2011
1
Outline of Presentation
• What is dose reconstruction?
• NTS Downwinders
– ORERP
– HHS Feasibility Study
• Chernobyl
• Semipalatinsk
• Mayak Production Association
– Techa River Cohort
– Ozersk Children’s Cohort
2
What is radiation-dose reconstruction?
• It involves reconstruction of radiation doses for
members of the public exposed to effluents from a
facility or exposed to a “practice.”
• Typically large numbers of the general public are of
interest—1000s to 100,000s or even 100,000,000s.
• Exposure may have been acute or chronic.
• It is common for environmental dose reconstruction to
be performed long after the beginning of exposure.
3
Hierarchy of methods of dose
reconstruction
• Individual biologic analysis
• Dosimetry of materials in homes—like thermal or
optical luminescence of quartz extracted from bricks
or porcelain
• Analysis of environmental residues
• Reconstruction of releases, plus atmospheric
transport models
4
My first major project was calculating
dose to downwinders of the Nevada Tests.
Bruce Church was Project Manager.
5
Analysis of environmental residues
• Historical measurements of external gamma-exposure
rate
• Deposition densities, historical or current data
– Short-lived radionuclides (historical only)
– 90Sr
– 129I
– 137Cs
– 239+240Pu, plus the ratio of 240Pu-to-239Pu
6
Environmental behavior of
radionuclides
7
• 100 atmospheric tests plus many vents.
• Collective external dose in the domain was
12,000 person-Gy.
• The U.S. Congress implemented a compensation
program, but based on politics, not science.
8
Collective dose, organ-gray
6
10
5
10
4
10
3
10
2
10
1
Thyroid
LLI
ULI
Bone surface
Red bone marrow
Small intestine
Stomach wall
Total body
Liver
Kidney
Ovaries
Uterus
Bladder wall
Adrenals
Spleen
Muscle
Pancreas
Testes
Lungs
Breast
Brain
Skin
10
Organ
9
There were two follow-on studies
mandated by the U.S. Congress.
• Dose to the thyroid from 131I for the 48 contiguous
states
• Dose to other organs from a select list of major doseforming radionuclides.
– External
– Internal
10
11
12
The ORERP work led to involvement at
Chernobyl
13
The destroyed reactor
14
Acute health effects
• Two workers died from physical trauma.
• 134 plant and emergency personnel had acute
radiation syndrome (ARS).
• 28 died
• 13 of the 28 had bone-marrow transplants, but
12 died.
• 3 of the 13 might have survived without the
transplants.
• No member of the public had ARS.
15
The first
UNSCEAR dose
assessment for
Chernobyl was
published in
1988.
16
The 2000 UNSCEAR
report was
controversial. It
reported there was no
substantial evidence of
latent health effects
other than childhoodthyroid cancer.
This finding was
rejected by the
governments of
Belarus, Ukraine, and
the Russian Federation.
There was lack of
agreement among the
UN agencies.
17
Chernobyl
• Doses were initially calculated based upon reported
values of 137Cs deposition, or other environmental
values.
• Thyroid measurements had been taken and were
made available.
• Later on, a huge data base on environmental
measurements and biologic dosimetry (including
whole body counts) became available.
18
Ground depositions of 137Cs
19
Ground depositions of 137Cs
20
21
22
23
24
Thyroid cancer in young people
after Chernobyl
• Major increase in risk :
– 6000 cases among those who were below 18 at
the time of the accident (1992-2005)
• Many epidemiological studies
– Confirm increased risk
– Provide estimates of risk per Gy
– Most cases attributable to radiation from the
accident
Adapted from E. Cardis, Intl. Agency for Research on Cancer, Lyon
25
Estimates of collective thyroid dose in
the three more affected countries
Country
Russian Federation
Belarus
Ukraine
Total
Collective thyroid dose, man-Gy
300,000
550,000
740,000
1,600,000
26
A good source of
detailed information
about Chernobyl.
You can download it
from the Internet.
27
Similar studies have been undertaken at
the former Soviet test site, Semipalatinsk,
located in Kazakhstan.
• Joint Russian-U.S. methodology
• New problem—the secretion of radioiodine in
– Camels
– Horses
– Sheep
• Basis of general dose reconstruction is historic
measurements of gamma-exposure rate, plus current
TLD and EPR measurements.
28
29
The Soviet ‘Sedan’ in Kazakhstan
30
The Mayak Production Association
• Was the first facility for the production of Pu in
the former USSR.
• Began operations in 1948.
• Due to unrecognized technological failures,
released about 1017 Bq of fission products into
the Techa River.
• Most of the release occurred during 19491951, but lower level releases continued
through 1956.
• There were also substantial airborne releases
of 131I.
31
1
1954
a
el y
sh
i
M
Bas
Metlinsky
Pond
Metlino
(7 km)
r
ive
R
k
1956
Rive
r
1952
kaz
yk
1950
Irtyash
Lake
Kyzyl-Tash
Lake
r
10
ve
Ri
100
et
Is
Radionuclide
composition, %
90Sr
- 11.6
89Sr
8.8
137Cs
- 12.2
95Zr, 95Nb 13.6
103,106Ru
- 25.9
Rare-earth
elements - 26.8
ka
ish
ut r
Sh ive
R
Average daily release, TBq
Techa River 1949-1956
Muslyumovo (78 km)
Techa
River
Brodokalmak (109 km)
Zyuzelka River
32
The exposed population
• Were members of an unselected general population.
• Lived along the banks of the Techa River in 40 villages.
• Were exposed mainly via
– Drinking water drawn from the River,
– Consumption of foods contaminated by river water,
– External exposure from the contaminated sediments
and flood-plain soils.
• Were relocated from the more heavily contaminated
villages beginning in 1955.
33
Pictures of the Techa River settlements
Former Metlino
located at 5-7 km from the
site of release
Muslyumovo
located at 78 km from the site
of release
As in 1965
As in 2000
34
The Techa River dosimetry and
epidemiology projects are integrated.
Disease
classification
Risk
derivation
Personal
Information
Disease
Follow-up
Dose
Dosimetry
system
Dose
calculation
All information is kept in
a central database at the URCRM.
35
Reconstruction of internal dose--89,90Sr
•
90Sr
is one of the main contributors to dose,
due to its hydrologic behavior
• It is retained the body in bone and teeth and
has been studied over long periods in the
same individuals.
• A special whole body counter is used and is
capable of measuring body burdens of 90Sr
through the detection of bremsstrahlung from
the decay of 90Sr/90Y.
36
37
Our dosimetry family portrait
38
ETRC solid cancer and leukemia dose
responses derived from TRDS-2000
Non-CLL Leukemias
10
0.6
Excess Relative Risk
Excess Relative Risk
Solid Cancers
0.4
Linear-Quadratic
0.2
Linear
0
0
0.2
Stomach Dose, Gy
0.4
8
6
Linear
4
Linear-Quadratic
2
0
0
0.5
1.0
RBM Dose, Gy
Krestinina LYu, Preston DL, Ostroumova EV et al. Protracted radiation exposure
and cancer mortality in the Techa River Cohort. Radiat Res 164:602-611; 2005.
39
Another cohort of interest is young
children living in Ozersk during the period
of major releases of 131I
• Epidemiologic studies have indicated an increased
prevalence of thyroid nodules and an increased
incidence of thyroid cancer in the exposed population.
• Study of this cohort could be very useful in resolving
differences in experiences from exposure to 131I from
Chernobyl vs. U.S. experience from the Nevada Test
Site and the Hanford Works.
40
Preliminary estimates of 131I release from
the Mayak Plant
41
42
Thank you for your attention.
43