Ministry of Health, Labour and Welfare

Ministry of Health, Labour and Welfare

20 September 2013
Office for Radiation Protection of Workers
Industrial Health Division
Occupational Safety and Health Department
Labour Standards Bureau

Press Release

Implementation status on medical examinations for workers engaged in radiation work in Fukushima Prefecture

  1. In accordance with the laws and regulation (Note 1), the Ministry of Health, Labour and Welfare has requested the employers to implement medical examinations for workers engaged in radiation and decontamination work, and to report the implementation status to the competent Labour Standards Inspection Office.

    Data from reports of each employer were analyzed and compiled to show the latest implementation status of medical examinations for workers engaged in radiation work etc. within the jurisdiction of the Fukushima Prefectural Labour Bureau (Note 3) including the Tomioka Labour Standards Inspection Office (Note 2). (See Annex for details.)

    (Note 1) "Ordinance on Prevention of Ionizing Radiation Hazards" (known as the Ionizing Radiation Ordinance), "Ordinance on Prevention of Ionizing Radiation Hazards at Works to Decontaminate Soil and Wastes Contaminated by Radioactive Materials Resulting from the Great East Japan Earthquake and Related Works" (known as the Ionizing Radiation Ordinance for Decontamination)

    (Note 2) The Labour Standards Inspection Office supervising TEPCO’s Fukushima Daiichi and Daini Nuclear Power Plants. Almost all of the workers who undertook the ionizing radiation medical examination in fiscal year 2012 were those who were engaged in works related to the nuclear power plants or decontamination.

    (Note 3) Approximately 80% of the workers who undertook the ionizing radiation medical examination in fiscal year 2012 were those who were engaged in works related to the nuclear power plants or decontamination. The other 20 % included health care and medical workers and educational institution researchers.


    Summary

    • The rate of having an abnormal finding in the ionizing radiation medical examination (Note 4)
      • The rate of having an abnormal finding in the ionizing radiation medical examination in 2012 was 6.90% as the national average, 6.26% within the jurisdiction of the Fukushima Prefectural Labour Bureau, and 4.21% within the jurisdiction of the Tomioka Labour Standards Inspection Office. These are 3 - 4 percentage points higher than those in 2010 which is before the disaster (Table 1).

      • Of the tests (based on the sampling survey within the jurisdiction of the Tomioka Office), "white blood cell count" showed the highest rate of having an abnormal finding of 2.2% This is 1.5 percentage points higher than that in 2010 (Table 2).

      (Note 4) "Have an abnormal finding" means the case where remarks were written by a medical doctor such as: "detailed examination required", "treatment required", or "follow-up required". It should be noted that the reference value in the clinical test is conventionally determined so as to include roughly 95% of both subjectively and objectively healthy individuals who meet certain criteria (reference individuals). It should also be noted that "white blood cell count" varies depending on other factors than radiation such as smoking and infectious diseases.


    • The rate of having an abnormal finding in the decontamination medical examination (Note 5)
      • The rate of having an abnormal finding in the decontamination medical examination in 2012 was 5.48% as the national average, and 5.48% within the jurisdiction of the Fukushima Prefectural Labour Bureau (Table 1).

      (Note 5) The implementation status is available only after 2012 because the Ionizing Radiation Ordinance for Decontamination did not become effective until January 2012.


    • The rate of having an abnormal finding in the general medical examination
      • The rate of having an abnormal finding in the general medical examination in 2012 was 53.11% within the jurisdiction of the Fukushima Prefectural Labour Bureau, which increased 1 percentage point compared to that in 2010. The table compiled for each office indicates that the rate of having an abnormal findings increased in some offices, and that it was 63.86% within the jurisdiction of the Tomioka office with an increase of 9.8 percentage points. The highest rate of having an abnormal finding was 48.42% for "lipid blood", which increased 11.50 percentage points (Tables 4 and 5).

    • Effective dose and change in reporting sites
      • While the rate of workers whose effective doses in 2011 exceeded 5 mSv was 32.5% in the ionizing radiation medical examination within the jurisdiction of the Fukushima Prefectural Labour Bureau, it was 1.9% in the decontamination medical examination. The weighted average estimates that were calculated with the median in each category were 10.26 mSv and 2.80 mSv respectively, for the ionizing radiation and decontamination medical examinations. The former was roughly 3.7 times larger than the latter (Table 3).

      • When comparing the sites that reported the results of the ionizing radiation medical examination in 2012 to those in 2010 within the jurisdiction of the Tomioka Office, it was found that 382 out of 545 sites (70.1%) that had reported in 2012 were different from those in 2010.

    • Discussion
      (1)    The data of 2010 and 2012 cannot be simply compared because 70% of the sites within the jurisdiction of the Tomioka Office that reported in 2012 were different from those in 2010 (i.e., the two groups are not identical). To evaluate changes in health through the comparison of the rate of having an abnormal finding in 2010 and 2012, information such as age distribution, lifestyle (habits of smoking, drinking, etc.), and medical history is required. However, such information was not included in the report.

      (2)    When comparing the rates of having an abnormal finding in the ionizing radiation and decontamination medical examinations with the effective dose distribution, the difference of the rates was as low as 0.78 percentage points (Table 1) while the distribution of the exposure dose differed significantly (Table 3). It is unclear whether there is a correlation between radiation exposure and changes in the rate of having an abnormal finding.

      It should be noted that there is no particular relationship observed from the general medical examination between the distance from the location of the Labour Standards Inspection Office to TEPCO’s Fukushima Daiichi Nuclear Power Plant and the rate of having an abnormal finding (Table 4).

      (3)    It was presumed that the increased implementation rate (approximately 20 percentage points) in each test may have influenced the increased rate of having an abnormal finding in the ionizing radiation medical examination in 2012 (Note 6). For this reason, a sampling survey was conducted on the rate of having an abnormal finding at each test item, which indicated that the highest rate of having an abnormal finding was 2.2% for "white blood cell count" with only the increase of 1.5 percentage points (Table 2).

      It should be noted that there is a 5% probability that the test value deviates from the reference range even if one is a "healthy person" without health impairment. Therefore, the rate of having an abnormal finding of 2.2% can be considered to fall within the range(Note4).

      (Note 6) The Ordinance on Prevention of Ionizing Radiation Hazards and the Ionizing Radiation Ordinance for Decontamination allow some of the tests (blood, eye, skin) except medical questionnaires to be omitted depending on the exposure dose in the previous year and based on a medical doctor's determination. Since the accident, the MHLW has provided instructions not to omit these tests for workers working in TEPCO’s Fukushima Daiichi Nuclear Power Plant regardless of radiation exposure dose.

      Consequently, the workers who undertook medical questionnaires but omitted blood tests in 2010 are counted in the denominator of the rate of having an abnormal finding (i.e., the number of examinees), but they are not counted in the numerator (i.e., the number of examinees who have an abnormal finding). This may have caused lower rates of having an abnormal finding in 2010.


  2. Actions by the MHLW

    (1)    The MHLW will provide instructions to TEPCO and the primary contractor to implement, in an appropriate manner, the follow-up actions described below for those having an abnormal finding.
    a.    Implement appropriate follow-up actions based on the guidelines for follow-up actions (Note 7).
    b.    Provide instruction and support by the primary contractor to the involved subcontractors.
    c.    Encourage the involved subcontractors to utilize the Fukushima Occupational Health Promotion Center and the Fukushima Prefecture Local Occupational Health Promotion Center.

    (2)    Rigorous epidemiological studies, including investigations on age distribution, smoking, drinking, and medical history, are vital to evaluate radiological health effects. Therefore, the MHLW will conduct necessary step-by-step epidemiological studies.
    a.    Fiscal year 2013: Studies on cataract and thyroid
    b.    After fiscal year 2014: Necessary studies will be conducted with a step-by-step approach, in addition to those conducted in fiscal year 2013.

    (Note 7) Guidelines for actions that should be taken by employers based on medical examination results (Guidelines No.1 for actions based on medical examination results, 1 October 1996). The guidelines include: (a) recommendations on undertaking secondary medical examinations, (b) obtaining opinions from medical doctors regarding medical examination results, (c) determining actions on working conditions, (d) notifying of medical examination results, and (e) providing health guidance.


(Annex) Implementation status on the medical examinations for workers engaged in radiation work in Fukushima Prefecture PDF 284KB
(Reference) Implementation status on the medical examinations for workers engaged in radiation work in Fukushima Prefecture PDF 531KB

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