韓国における診断医用放射線技師の職業的放射線被曝と循環器疾患の罹患率

Occupational radiation exposure and morbidity of circulatory disease among diagnostic medical radiation workers in South Korea.

• Eun Shil Cha
• Lydia B Zablotska
• Ye Jin Bang
• Won Jin Lee

抄録

目的:

診断医用放射線従事者の低線量外部職業放射線被曝と循環器疾患の罹患率との関連を調査した。

OBJECTIVES: We investigated the association between low-dose external occupational radiation exposure and circulatory disease morbidity among diagnostic medical radiation workers.

方法:

診断用放射線業務従事者11500人のコホートを、全国線量登録データと国民健康保険サービスデータとの関連付けを行った。職業的要因と循環器疾患の罹患率との関連を調べるために相対リスク（RR）を計算し、100ミリグレイ当たりの過剰相対リスク（ERR/100mGy）を推定して放射線量と放射線量の反応関係を定量化した。

METHODS: A cohort of 11 500 diagnostic medical radiation workers was linked with the National Dosimetry Registry data and the National Health Insurance Service data. Relative risks (RRs) were calculated to explore the association between occupational factors and circulatory disease morbidity, and excess relative risks per 100 milligray (ERR/100 mGy) were estimated to quantify the radiation dose-response relationship.

結果:

全体では、観察期間93,696人年（平均追跡期間＝8.1年）の間に循環器疾患の発症は2270例であった。高血圧症のRRは、2000年以前に勤務を開始した人が2005年以降に勤務を開始した人に比べて有意に増加した。すべての循環器疾患のERR/100mGyは0.14（95％CI -0.57～0.99）であった。脳血管疾患および虚血性心疾患の放射線リスクは、個々の心臓への累積線量を推定すると有意ではなかった（ERR/100mGy=3.10（-0.75～11.59）、1.22（-0.71～4.73））。しかし、ERRの推定値は一般的に女性対男性、若年者対50歳以上の労働者でより強く正の値を示した。

RESULTS: Overall, there were 2270 cases of circulatory diseases during 93 696 person-years of observation (average follow-up=8.1 years). RRs for hypertension were significantly increased for individuals who started working before 2000 compared with those who started in 2005 and later. ERR/100 mGy for all circulatory diseases was 0.14 (95% CI -0.57 to 0.99). Radiation risks of cerebrovascular diseases and ischaemic heart disease were non-significantly increased with estimates of individual cumulative doses to the heart (ERR/100 mGy=3.10 (-0.75 to 11.59) and 1.22 (-0.71 to 4.73), respectively). However, ERR estimates were generally more strongly positive for female versus male workers and for younger workers versus more than 50-year-old workers.

結論:

本研究では、韓国の医療用放射線従事者を対象とした短期間の追跡調査において、職業的放射線被曝と循環器疾患の全リスクとの間の正の関連性を支持する証拠はほとんど得られていない。しかし、初勤務年が早いほどRRが有意に上昇し、女性労働者および若年労働者ではERRが上昇していることから、さらに追跡調査を行う必要があると考えられる。

CONCLUSIONS: This study provides little evidence in support of a positive association between occupational radiation exposure and the overall risk of circulatory disease over a short follow-up period among medical radiation workers in South Korea. However, significantly increased RR with earlier year first worked, elevated ERR in female workers and young workers should be further followed up.

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