Understanding the Long-Term Implications of Severe ...

United Nations Scientific Committee on the Effects of Atomic Radiation

Wolfgang Weiss (Germany), UNSCEAR

International Experts’ Meeting on Decommissioning and Remediation after a Nuclear Accident Organized in connection with the implementation of theIAEA Action Plan on Nuclear Safety

Understanding the Long -Term Implications

of Severe Radiological Accidents (including Infrastructure and Resource Needs)

United Nations Scientific Committee on the Effects of Atomic Radiation 2


Characteristics of the Process

During the remediation process, theapplication of the radiation protectionprinciples „justification “ and „optimization “has to be conducted with great care todeploy remediation actions which are theresult of a balance between objectiveelements (exposure, costs, etc.) andsubjective elements (public perception,anxiety, political pressure, etc.).

PreparednessResponse Recovery

Early Intermediate Late

Planning

Stage

Event/Respons

e Initiation

Crisis

Managemen

t

Consequenc

e

Managemen

t

Transition

to

Recovery

(including

recovery

planning)

Recovery/Long-

term

Rehabilitation

Emergency Exposure Situation

Existing

Exposure

Situation

Emergency Management Timeline

Available information or Stakeholder involvement

Homma 2012

Past experience


Long -term experience of chronic exposuresituations is readily available from nucleartest sites (Bikini, Maralinga), nuclearaccidents (Kyshtym, Palomares, Chernobyl,Fukushima), or radiological source accidents(Goiaˆnia).

UNSCEARs Chernobyl experience



ICRP recommendations

Challenges


The available experience clearly showsthat all dimensions of the daily life of theinhabitants within contaminated areas, aswell as the social and economic activities,are affected resulting in complex situationswhich cannot be managed with radiationprotection considerations alone.

Multiple dimensions


Remediation actions must address allrelevant dimensions such as health,environmental, economic, social,psychological, cultural, ethical, political ,etc..

Following WHO's definition health is:"A state of complete physical, mental andsocial well-being, and not merely theabsence of disease".

The responsibilities of authorities


The first priority of strategies implementedby authorities is to protect people with thehighest exposures, and in parallel toreduce all individual exposures to as low asreasonably achievable. This impliesassessments of the dose distribution,comparison of the doses with the referencelevel, and subsequent optimisation ofprotection .

There is a strong need for transparency ofthe underlying processes.

Key elements of implementation strategies


Clean-up of buildings, remediation of soilsand vegetation, changes in animalhusbandry, monitoring of the environmentand produce, provision of clean foodstuffs,managing of waste (resulting from clean -upor from unmarketable contaminated goods),provision of information, guidance,instruction and equipment (e.g. formeasurements), health surveillance,education of children, information forparticular exposed groups and the public atlarge, etc..

Dose-dependent health effects

Clinical effects• Acute radiation

syndrome• Local injuries

Clinical effects• Acute radiation

syndrome• Local injuries

CancerCancer

Hereditary effects

Hereditary effects

Other• Fetal effects• Cataracts• Cardiovascular

Other• Fetal effects• Cataracts• Cardiovascular


Late health effects – Chernobyl


The major health consequences from theradiation exposure of the ARS survivorsremain skin injuries and radiation -inducedcataracts. A high prevalence of nervoussystem diseases among the survivors hasbeen registered . Similarly, there have beenreports of a high percentage ofcardiovascular and gastrointestinal diseases.Among the ARS survivors there have been afew confirmed cases of solid cancer.



A substantial increase in the incidence ofthyroid cancer has occurred in the threerepublics since the Chernobyl accidentamong those exposed as children oradolescents. The increase of thyroidcancer among children and adolescentsbegan to appear about 5 years after theaccident and persisted up until 2005.


In order to guide decision -making on publichealth resource management, and given thatthere is a latent period between exposure andthe appearance of any increased incidence instochastic effects, attempts have been madeto predict the health impact on populationsexposed to radiation by applying radiationrisk models to the estimates of populationdose.


Interpretation of radiation risk projections


The interpretation and communication ofradiation risk projections is fraught withmany difficulties, and it is not easy tocommunicate the intrinsic scientific limi-tations of attribution of health effectsadequately. There are no biomarkers specificto radiation available and it is not possible tostate scientifically that radiation caused aparticular cancer in an individual . This meansthat in terms of specific individuals, it isimpossible to determine whether theircancers are due to the effects of radiation orto other causes.

Attribution of health effects at low doses


Due to the great uncertainties in riskestimates at very low doses, UNSCEARdoes not recommend multiplying very lowdoses by large numbers of individuals toestimate numbers of radiation -inducedhealth effects within a population exposedto incremental doses at levels equivalentto or lower than natural background levels.

Options to evaluate long term cancer risks


Two types of studies are considered byUNSCEAR when evaluating the cancer risk topopulations exposed during the Chernobylaccident:• geographical correlation studies relating

aggregated rates of disease with averageexposure and

• analytical studies ( case-control or cohort )where individual information is used .

Other causes of health effects


The Chernobyl accident is known to havehad major effects that are not related to theradiation exposure. They include effectsbrought on by anxiety about the future anddistress , and any resulting changes in diet,smoking habits, alcohol consumption andother lifestyle factors, and are essentiallyunrelated to any actual radiation exposure.

Other causes of health effects


The Chernobyl Forum concluded that stresssymptoms, increased levels of depression,anxiety (including post-traumatic stresssymptoms ), and medically unexplainedphysical symptoms , have been found in theexposed populations compared to controlgroups. Mostly, these conditions weresubclinical and did not meet the criteria forclassification as psychiatric disorders.

Effects of similar nature have been observedafter the Fukushima nuclear accident.


Needs identified by ICRP

• a monitoring record system beestablished under the responsibility ofthe relevant authorities.

• health registries be established for thepopulation residing in the affectedareas.



Quantifcation of the intrinsic uncertainties isan integral part of the estimation of theannual doses. Whenever possible, annualdoses should be reported as a distribution ofpossible values rather than as single pointvalues. Radioactive residues are usuallyunevenly distributed, creating situations ofheterogeneous prolonged exposure. Theseneed to be addressed on a case-by-casebasis by making realistic assumptions aboutthe pattern of people's exposure.


In most cases in long -term exposuresituations, the level of exposure is drivenby individual behaviour .

It is an obligation of the authorities tofacilitate processes to allow inhabitants todefine, optimise, and apply their own(„self-help “ ) protective actions.


Key aspects of self help


Thank you for your attention


Contact details: [email protected]

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