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Looking Back on Chernobyl:
A Public Health Perspective
Timothy J. Jorgensen, PhD, MPH
Associate Professor of Radiation Medicine
Director, Health Physics and Radiation Protection Program
Georgetown University
3970 Reservoir Road, NW, TRB Room EG16, Washington DC 20057
email: [email protected]
program website: http://healthphysics.georgetown.edu/
author website: http://www.timothyjorgensen.com/
Twitter: @Tim_Jorgensen
The Fundamentals of Radiation Biology
Two Routes of Exposure to the Body:
• External: sources of radiation/radioactivity outside the body
(e.g. nuclear blast radiation)
• Internal: radioactivity inside the body (e.g. nuclear fallout)
Two Types of Exposure to the Body:
• Whole-Body: all organs exposed (e.g. Hiroshima)
• Partial-Body: specific organs exposed (e.g. I-131 at Chernobyl)
If you know the route of exposure, the type of exposure, and the amount
of exposure, you can calculate organ and whole-body doses fairly
accurately.
Since dose drives health effects, you can predict the type and severity
of health consequence by just knowing the doses among individuals.
@Tim_Jorgensen
LD50
= THRESHOLD FOR DEATH
The Health Consequences are Driven by Dose
1,000 mSv threshold
for radiation sickness
NOTE: The “millisievert” (mSv) is the Standard International dose unit for radiation protection
purposes. All countries in the world use it, except for the United States government, which still
uses the older unit, the “millirem” (mrem). (1 mSv= 100 mrem)
@Tim_Jorgensen
Radiation Sickness Dose Range
LD50
LD50
hematopoietic
syndrome
(death in weeks)
1,000 mSv
∂
∂
GI
syndrome
CNS
syndrome
(death in days)
(death in hours)
10,000 mSv
5,000 mSv
15,000 mSv
WHOLE-BODY DOSES
SURVIVORS
TREAT
•
•
•
•
•
@Tim_Jorgensen
antibiotics
IV fluids
transfusions
growth factors
BMT
FATALITIES
20,000 mSv
Radiation Sickness Dose Ranges
LD50
LD50
hematopoietic
syndrome
(death in weeks)
∂
CNS
syndrome
(death in days)
(death in hours)
TREATMENT
BENEFIT
NO BENEFIT
1,000 mSv
∂
GI
syndrome
5,000 mSv
NO BENEFIT
10,000 mSv
15,000 mSv
WHOLE-BODY DOSES
SURVIVORS
@Tim_Jorgensen
TREAT
FATALITIES
20,000 mSv
FALLOUT
HIROSHIMA
CHERNOBYL
FALLOUT INVOLVEMENT
Fallout hazard
No fallout
hazard
IND
RDD
@Tim_Jorgensen
LOCAL DEPOSITION
WIND
hundreds of miles
RAIN
CONCERNS AT NON-LETHAL DOSES (<1,000 mSv):
• Increased risk of cancer
• There are no currently no medical countermeasures available to reduce
the cancer risk, and none likely in foreseeable future.*
• When should people be evacuated?
• How do we clean it all up?
• What is clean enough?
• When is it safe to return?
What can nuclear power plant accidents tell us?
@Tim_Jorgensen
*Yoo SS, Jorgensen TJ, Kennedy AR, Boice JD Jr., et al. Mitigating the risk of radiation-induced cancers:
limitations and paradigms in drug development. J Radiol Prot. 2014 Jun; 34(2):R25-52. doi:
10.1088/0952-4746/34/2/R25. Epub 2014 Apr 14.
Drug treatment
Fukushima was no Chernobyl
@Tim_Jorgensen
Radiation Casualties
Chernobyl
•
•
•
•
127 cases of radiation sickness
54 deaths from radiation sickness
16,000 thyroid cancers
23,000 other cancers
Fukushima
•
•
•
•
no cases of radiation sickness
no deaths from radiation sickness
no significant increase in thyroid cancers
no significant increase in other cancers
When will it be safe for people to return home?
@Tim_Jorgensen
The Fukushima Question: Is 20 mSv per year “safe”?
Before Fukushima: annual limit to public was 1 mSv/yr
After Fukushima: mitigation goal for rehabitation is 20 mSv/yr
Answer:
• For radiation sickness it is safe, because radiation sickness has a
threshold of about 1,000 mSv.
• For cancer risk, it depends who you ask.
Consider the risk:
• 20 mSv per year has a cancer risk of about 1: 1,000 per year
• Stated another way, if 1,000 returning evacuees lived for one year at 20
mSv per year, we would expect 1 of them to ultimately develop cancer
from their exposure.
• Stated yet another way, out of 1,000 randomly selected people, we
would expect 250 to die of cancer (because cancer is a common
disease). If all 1,000 also received a 20 mSv dose we would expect the
cancer death number to go up to 251.
@Tim_Jorgensen
Ask yourself: Is this level of risk “safe”?
Some Lessons Learned from Nuclear Power Plant Accidents*
•
Widespread contamination may limit access and inhibit the recovery efforts.
•
Evacuation for purely radiation exposure reasons may cause more harm than good.
•
Late phase recovery is not a one-time effort but rather a long-term continuous and iterative
program where exposures/doses are gradually reduced over time, requiring large amounts
of money.*
•
Fear and anxiety over radiation is one of the most important considerations that late-phase
recovery must deal with.
•
Transparent decision-making is the only means to get stakeholders to “buy into” the
recovery efforts and establish trust.
•
Clean-up to the levels of traditional statutory regulatory exposure limits could take decades,
if possible at all. Such a protracted efforts are damaging to the communities economic and
social well-being. More damaging that the radiation.
*
• ICRP Publication 111: Application of Commission Recommendations to the Protection of People Living in Long-Term Contamination
Areas After a Nuclear Accident or a Radiation Emergency (2009).
• NCRP Report No. 175. Decision Making for Late-Phase Recovery from Major Nuclear and Radiological Incidents. Bethesda MD: National
Council on Radiation Protection and Measurements, (2014): Appendix A: Lessons Learned from Historical Incidents.
One lesson that hasn’t been learned yet:
The public needs to be educated about radiation threats.
“There has been no education regarding radiation,” says Katsunobu
Sakurai, the mayor of Minamisoma, where 14,000 people were
evacuated after the accident. “It's difficult for many people to make the
decision to return without knowing what these radiation levels mean
and what is safe,” he says.
-- Science, March 4, 2016
(5 years after Fukushima accident)
@Tim_Jorgensen
No easy solution … but public health officials could do a better job by
educating the public about radiation before an incident occurs.*
•
Radiation risk education needs to happen as early a possible and not be relegated to
merely a component of the late-phase recovery plan.
•
Ideally education should take place prior to an incident, particularly for those living near nuclear power pants
or in high-risk terrorist target sites.
If it did not occur prior to an incident, then education should commence during early and middle phase
recovery efforts, as much as possible.
•
•
People need to be given a working knowledge of what the terms radiation,
radioactivity, and dose mean.
•
•
Radiation risk should be depicted as just one of many risks that victims face as a
result of an incident (e.g. radiation terrorist attack), and usually not the major risk.
•
•
•
Without this minimal technical understands it is difficult to engage in meaningful conversation about risk.
Trauma
Burns
Radiation risk should be portrayed as an inescapable part of living, and the level of
the risk depends upon dose. By deciding personal risk tolerance, an acceptable
individual dose level can be determined.
•
•
This dose will vary tremendously from individual to individual, and will depend on the competing risk and
benefits.
Since competing risks and benefit are specific to individuals, only individuals can do a meaningful risk
benefit analysis that is uniquely appropriate for them.
*Jorgensen, TJ. The New “Normal”: Stakeholders and Radiation Protection Limits in a Post-9/11 World. Health
Physics (in press).
1 mrem = 10 microSv
U.S. vs. international
@Tim_Jorgensen