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The International Workshop on Radiation and Thyroid Cancer ( Day 2 )

The International Workshop on Radiation and Thyroid Cancer ( Day 2 ). Dose Estimation. Effects Identification. Dose Response Relationship. Risk Estimation. Session 2:  Dose Estimations for Those Affected in Fukushima Prefecture.

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The International Workshop on Radiation and Thyroid Cancer ( Day 2 )

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  1. The International Workshop onRadiation and Thyroid Cancer (Day 2 ) Dose Estimation Effects Identification Dose Response Relationship Risk Estimation

  2. Session 2:  Dose Estimations for Those Affected in Fukushima Prefecture • Dose estimations by WHO, FMU, NIRS, and Hirosaki Univ. were presented. • The more recent estimations (FMU, NIRS, Hirosaki Univ.) are lower than the WHO value. • External doses, for the first four months, have been estimated for more than 470,000 respondents from the Basic Survey. • The effective dose distribution (excluding workers): <1 mSv, 66.3%, <2 mSv, 94.9%, <3 mSv, 99.3%

  3. Session 2:  Dose Estimations for Those Affected in Fukushima Prefecture • Independent estimations indicated that the internal thyroid doses were around 30 mSv at 90 percentile for small children in relatively high dose areas. • Individual determinations of thyroid dose are important to be communicated back to the individual so they can make informed decisions about the management of their health. • To improving the dose estimation; • Clarification on the source term, the ratio of radioactive Iodine to Cesium. • Additional analyses, e.g. combination of internal dose measurement and evacuation routes of the evacuees .

  4. Session 3: Thyroid Ultrasound Examinationsand Thyroid Cancers • Thyroid ultrasound examinations has been started on all children in the Fukushima Prefecture. • There has been an increase in childhood thyroid cancer in prefectures far from Fukushima and in Korea. • Base-line vs Radiation-associated Thyroid Cancer: • Dose-response relationship. • Latency period ( 4 to 5 years for radiation-induced thyroid cancer ) • Age distribution (More in younger, if radiation-induced) • What is being seen now should be used as the baseline for thyroid cancer into the future.

  5. Session 4: Thyroid Cancer Risk Estimates • Experts expect an incidence of thyroid cancer, after 1st screening of 0.3 cases per 100,000 person-years. Expect a 6 times larger incidence in later screening as the population ages. • As of September 2013 the observed prevalence of thyroid cancer in Fukushima is 0.031%. • It will be important to use standard approaches for realistic dose reconstruction and analytical epidemiological studies. • Maternal radioiodine exposure is the pathway for thyroid dose to the fetus. • Fetal thyroid dose is largest in the third trimester of pregnancy.

  6. The International Workshop on Radiation and Thyroid Cancer(Day 2 ) Dose Estimation Effects Identification Dose Response Relationship Risk Estimation

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