This is the presentation I made at the 2015 Health Physics Society Annual Meeting, in the Special Session called "Health Risks from Low Doses and Low Dose-Rates of Ionizing Radiation" on July 14, 2015.

1. Future of radiation protection regulations
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Mohan Doss, PhD, MCCPM
Medical Physicist, Diagnostic Imaging
Fox Chase Cancer Center,
Philadelphia, PA
E-mail: mohan.doss@fccc.edu
2015 Health Physics Society Annual Meeting, Special Session:
Health Risks from Low Doses and Low Dose-Rates of Ionizing Radiation
July 14, 2015
Copyright © 2015 by Mohan Doss
Version 1.01, Release date: July 15, 2015
This presentation in its entirety may be copied, shared, and distributed freely without any restriction.
If using individual slides or figures, please acknowledge this presentation as the source.
Disclaimer: Opinions expressed in this presentation are my own professional opinion,
and do not necessarily represent those of my employer.

2. How do we decide on radiation protection regulations for
low-dose radiation (LDR)?
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3. How do we decide on radiation protection regulations for
low-dose radiation (LDR)?
It is elementary.
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4. How do we decide on radiation protection regulations for
low-dose radiation (LDR)?
1. If LDR increases cancer risk
Regulation: Avoid/Reduce LDR exposures
2. If LDR decreases cancer risk
Regulation: None or minimal, so that
LDR can be used to reduce cancers.
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5. After we set up regulations,
• Be on the lookout for evidence contradicting the
hypothesis used.
• If new evidence contradicts the assumed hypothesis,
revise the regulations in accordance with new
knowledge.
• Do this promptly, to minimize danger to public from
the use of the wrong hypothesis.
What should we do if there is insufficient
knowledge of LDR cancer risks?
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6. Cancer risk in populations exposed to
low-dose radiation
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All the data show reduction of
cancers following low-dose
radiation exposures

7. 7
LNT Model: Using radiation cancer risk coefficients
averaged for males and females from BEIR VII Report

8. 8
Additional Data on Cancer risk in Populations Exposed
to Low-dose Radiation
All the data show no increase in cancers or reduction of cancer for low doses.

9. Cancer Patient Survival after 10-15 cGy total body or half-body
irradiation repeated during 5 weeks (Total dose = 1.5 Gy)
Survival following repeated low-dose total
body irradiation was as well as or better than
chemotherapy
Addition of Low-dose
total body or half body
irradiation resulted in
better survival than
radiation therapy alone

10. 10
Green ovals enclose high radon level areas; Red ovals enclose areas having high lung cancer
rates. There is little overlap between red ovals and green ovals.

11. 11
Radon Levels and Lung Cancer in UK

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16. 16
Radon Levels and Lung Cancer in USA

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Note: Iowa is the state that has the highest average radon levels in the USA.
The areas marked as “Exceptions” have high radon levels and high lung cancer rates.

18. Radon Levels and Lung Cancers in TEXAS
Note: Texas is a state with some of the lowest radon levels in the USA
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19. Note: California has the second lowest smoking rate in the USA
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20. Note: Kentucky has the highest smoking rate in the USA
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Kentucky

21. Note: West Virginia has the second highest smoking rate in the USA
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Ozasa et al. (2012) state: The curvature has become significant with
longer observation. Curvature apparently due to lower than expected
risks in the 0.3-0.7 Gy range.
Doss (2012): A-bomb survivor data more consistent with radiation
hormesis than LNT model
Dr. Mark Little (NCI) in Debate (Doss, 2014): did not use A-bomb
data to claim support for the LNT model.
Actions speak louder than words.
Major change in
nature of dose-
response shape in
A-bomb survivor
cancer mortality
data with recent
update.

24. 24
Nov 2014 - Scoping Meeting for BEIR VIII report at NAS:
No discussion of impact of Ozasa data on LNT model
June 2015 - Open Meeting of NRSB at NAS.
Dr. Puskin (EPA) said: Not much has changed in the A-
bomb survivor data, regarding LDR cancer risk.
ICRP, NCRP, UNSCEAR, IAEA, WHO, NRC, CNSC: No
recognition of impact of the update on the LNT model.
Nobody is on the lookout for evidence contradicting the
hypothesis used, to minimize danger to public from
current recommended regulations.
How did advisory and regulatory bodies respond to
this major change in A-bomb survivor data?

25. How about publications claiming LDR
increases cancer risk?
•The record of publications that have claimed
increased cancer risk from LDR has been pathetic,
with their conclusion negated on a later date due
to faults identified, corrections to the
data/analysis/interpretation, or updates to the
data.
•There is not even a single publication with
conclusive evidence that LDR increases cancer
risk, that has withstood the test of time.
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26. 26
Conclusion based on
current state of knowledge:
LDR reduces cancer risk.

27. In view of evidence for radiation hormesis,
how should we regulate radiation use?
• We should identify types of radiation
exposures that can cause harm
• Establish regulations to prevent such
radiation exposures
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28. Acute Radiation Exposures
In view of uncertainties in Data and Dosimetry
 Threshold dose could be as low as 35 cGy.
Applying an additional safety factor of 3
 Acute dose of 10 cGy can be considered to be well
below the threshold dose for increased cancers, and so safe.
Suggested Regulation:
Dose guidance level of 10 cGy for acute exposures.
For acute exposures, the atomic bomb survivor
data indicate a threshold dose of ~70 cGy for
increased cancer risk (Doss, 2013).
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29. Radiation Exposures over
Extended Periods of Time
• Increased cancers have been observed
following radiation exposures over extended
periods of time also, but the threshold dose
for increased cancers has been higher.
• Cumulative radiation doses, which are clearly
carcinogenic in acute exposure situations,
have shown a cancer preventive effect.
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30. Details of Studies and Reference(s) Duration
of
radiation
exposure
Range of
cumulative
doses (Gy)
Threshold
dose (Gy) for
increased
cancers
Cumulative
dose for
reduction
of cancers
Thyroid cancers following diagnostic I-131
administration in children (Hahn et al.,
2001)
A few
weeks
0-7 Gy 1.5 Gy -
Cancer patient survival following periodic
low-dose total-body (or half-body)
irradiation (Chaffey et al., 1976), (Choi et
al., 1979), (Sakamoto, 2004), (Mendenhall
et al., 1989)
5 weeks 1.5 Gy to 3 Gy
whole body or
half-body
2 Gy 1.5 Gy
Second cancers in radiation therapy
patients (Tubiana et al., 2011), (Suit et al.,
2007)
6 weeks 0.05 Gy to 60
Gy to different
parts of body
2 Gy ~0.2 Gy
Breast and lung cancers in TB patients
who underwent repeated fluoroscopic
examinations (Howe and McLaughlin,
1996), (Davis et al., 1989), (Rossi and
Zaider, 1997)
3 years 0-18 Gy Chest 1 Gy for
Breast
Cancer,
2 Gy for
Lung Cancer
~0.8 Gy for
Lung
Cancer
Bone sarcomas in radium dial painters
(Evans, 1974), (Rowland, 1996)
40-50 yrs 0-500 Gy 10 Gy -
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31. Lowest threshold dose
- 1 Gy for exposure over 3 years or
~30 cGy for exposure during 1 year
Using a safety factor of 3:
10 cGy per year can be considered to be safe
Suggested Regulation, for exposures over
extended periods of time:
Dose guidance Level of 10 cGy per year
Radiation Exposures over
Extended Periods of Time
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32. • Dose Guidance Level is Not a Dose Limit
• Guidance means: Caution not to exceed this value
significantly in order to stay in the safe zone
• Doses somewhat above guidance level would not be of
concern
• If dose guidance level were exceeded by a factor of 2 or
more, could face increased risk of cancer – this should be
avoided
• Same dose guidance level for radiation workers and the
public. We want everyone to be safe, unlike present
regulations that penalize radiation workers with increased
cancer risk (according to their own estimations using the
LNT model)
Dose Guidance Level of 10 cGy acute Dose
or Annual Dose
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33. New Paradigm of Radiation Protection
• The new paradigm would encourage
prospective studies of health effects of LDR
• No more ALARA
• But, care in the use of LDR will be mandatory,
to avoid exceeding the dose guidance levels
significantly.
• Most current radiation protection regulations
and practices would be limited to potential
high radiation exposure situations, and would
not apply to LDR.
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34. Big Changes are Ahead … maybe.
• NRC is currently considering three petitions
asking it to change the basis of its regulations
from the LNT model to the radiation hormesis
model, rather than dismissing the petitions.
• This is indeed unexpected, encouraging news
and may portend forthcoming changes.
• Comments so far have overwhelmingly
supported the move away from the LNT
model.
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35. Questions:
• How can we speed up the change?
• How do we convince advisory bodies and
regulatory agencies to recognize the evidences
and accept change?
• How do we convince the public that LDR is safe?
• How do we convince governments to act?
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