Cancer - Dose Assessment and Risk Factors

Transcription

1 Evaluación de riesgo sobre la salud en respuesta al accidente de Fukushima-Daiichi Dra Maria del Rosario Pérez Departamento de Salud Pública y Medio Ambiente

2 WHO Response to Fukushima accident Headquarters Geneva 1 WHO emergency response plan was immediately activated with continuous situation monitoring from 1, 2, 3 Western Pacific Regional Office (WPRO, Manila) 2 3 Kobe Centre

3 WHO short-term response actions Relevant WHO technical programs (Radiation Team, Water and Sanitation, Food Safety, Children Health, Mental Health, etc.) and expert networks (REMPAN, INFOSAN) to assess health risks and provide advice on public health measures Technical support to national authorities (food, water, travel, transport, trade, mental health, public information ) Continuous information to governments, media, public (dedicated website, media statements, press conferences, Fact Sheets and Q&As, social networks - Facebook, Twitter, etc.)

4 Crisis communication- lessons learned. Importance of providing timely and accurate information To inform decision-making (e.g. travel, trade) To prevent risky reactions (e.g. potassium iodide) To allay unnecessary fears (e.g. travel, breastfeeding) To promote healthy behaviours

5 WHO assessment of health risk resulting from Fukushima Daiichi NPP

6 Health Risk Assessment To fulfil WHO's role and responsibilities under the Joint Plan To provide information for Member States and the public To identify needs and priorities for public health action including health surveillance and long-term epidemiological studies ma_dose_assessment/en/ ma_risk_assessment_2013/en/index.html

7 HRA report: the steps Hazard Identification What is the agent and what health problems are potentially caused by the agent? Exposure Assessment What exposures are likely to occur, and what is the resulting dose to humans? Dose-response Relationship What are the health problems at different exposures? Risk Characterization What is the extra risk of health problems in the exposed population?

8 WHO Preliminary Dose Assessment International Panel established by WHO to conduct an initial assessment of radiation exposure of populations inside and outside Japan June 2011 Independent scientific experts from UK (HPA), Russia (IRH), Germany (BfS), Japan (NIRS, NIPH), USA Representatives from WHO, IAEA and FAO Observers UNSCEAR and the Government of Japan Observers:

9 Independent experts Lynn Anspaugh Mikhail Balonov Carl Blackburn Florian Gering Stephanie Haywood Jean-René Jourdan Gerhard Proehl Shin Saigusa Jane Simmonds Ichiro Yamaguchi and other contributors listed in the report

10 International Dose Assessment Expert Panel Planning meeting (30 June 2011) Working meeting- assumptions, scenarios, approaches (5-6 Sept 2011) Compilation of measurement data in Japan and human monitoring data performed outside Japan (end Sept 2011) Radiation dose assessment and expert meeting to review and discuss study results (Oct 2011) Draft reports v01, v02, v03 (Nov-Dec 2011) Final review and editing (Jan-Feb 2012) Publication (May 2012) Planning Meeting / Vienna, 30 June Working Meeting / Geneva, 5-6 Sept Review Meeting / Geneva, Oct.

11 Assessed exposure pathways IAEA report on Environmental consequences of the Chernobyl accident and their remediation: twenty years of experience (2006)

12 WHO Health Risk Assessment Observers:

13 Independent experts Makoto Akashi Billy Amzal Lynn Anspaugh Anssi Auvinen Nick Gent Peter Jacob Dominique Laurier Charles Miller Ohtsura Niwa Roy Shore Richard Wakeford Linda Walsh Wei Zhang and other contributors listed in the report

14 Health Risk Assessment Working Group December 2011: WHO established a HRA WG and convened 1 st meeting to agree on working methods, dose response models, age groups, end points, work plan and timeline March 2012: 2 nd HRA WG meeting discussed results, identified gaps and areas requiring refinement, reviewed the HRA report outline, agreed on next steps Geneva, December 2011 Geneva, March 2012 Report completed in December 2012; editing, formatting, proof reading in Jan-Feb 2013, published end of Feb 2013.

15 Scope Radiation doses and risks to the public and workers (since workers doses were not assessed by the panel, dose estimations provided by TEPCO were used ) Different age groups Public: 1y infants, 10y children and 20y adults (females and males) Workers: 20, 40, 60 year olds (males) Global geographical coverage Fukushima Prefecture Other prefectures in Japan Countries neighbouring Japan Other regions of the world (excluding the evacuation zone within 20 km of the NPP): no dosimetric data

16

17 End-points of the HRA Lifetime Attributable Risk (LAR) estimates of radiation-related cancer risk based on organ doses: all solid cancers incidence leukaemia incidence thyroid cancer incidence female breast cancer incidence Non-cancer risks were considered but not modeled (thyroid nodules, thyroid dysfunction, visual impairment, circulatory diseases, reproductive dysfunctions, risk of radiation-induced tissue damage and developmental changes in embryo and fetus)

18

19 Lifetime dose model - ratio of lifetime dose to 1-year dose On the basis of the Chernobyl experience, and taking into consideration the differences between the Chernobyl and Fukushima Daiichi NPP accidents, the HRA Expert Group considered it reasonable to assume that the ratio of long-term dose to 1-year dose would be equal to 2 and that the result should be treated as a lifetime dose commitment

20

21

22 Japanese survival curve, Probabilty of cancer free survival Male and Female Male survival curve Female survival curve Age at lower boundary of the Age group (years) Lifetime baseline risk (LBR) based on cancer incidence rates from a general population is the cumulated baseline probability of having a specific cancer over the lifetime LBR All solid cancer Thyroid Leukaemia Breast Males Females

23 Lifetime Fractional Risk (LFR) LAR can be scaled to the lifetime spontaneous cancer incidence in the reference population (LBR) LFR = LAR/LBR. LFR is more suggestive of the actual level of a radiation risk than the LAR.

24 LAR (x 10-2 )

25 LAR (x 10-2)

26 LAR (x 10-2) LFR~70%

27 LAR (x 10-2)

28 The occupational health assessment

29 Occupational doses workers 5,639: TEPCO (24%) 17,533: contracted (76%) Maximum total effective dose: msv Maximum internal dose: 590 msv

30 Occupational doses

31 Workers thyroid doses Dose (msv) Workers > 10,000 2 > 2,000 10,000 or < 10 > 1,000 2,000 or < 32 > 500 1,000 or < 50 > or < 69 > or < or < 344

32 Considerations The dose estimates and assumptions used in this assessment were deliberately chosen to minimize the possibility of underestimating eventual health risks so some overestimation of doses may have occurred. The results should be regarded as inferences of the magnitude of health risks (not effects). Because scientific understanding of radiation effects, particularly at low doses, may increase in the future, it is possible that further investigation may change our understanding of the risks of this nuclear accident.

33 Conclusions No discernible increase in health risks from the Fukushima event is expected outside Japan. With respect to Japan, this HRA estimates that the lifetime risk for some cancers may be somewhat elevated above baseline rates in certain age and sex groups that were in the areas most affected. These estimates provide information for setting priorities in the coming years for population health monitoring, as has already begun with the Fukushima Health Management. If more precise dose estimations become available (e.g. UNSCEAR study), such data can be used to further refine these risk estimates.