研究のタイプ: 疫学研究 (observational study)

[英国における電力線と小児がんの疫学研究:詳細分析] epidem.

Epidemiological study of power lines and childhood cancer in the UK: further analyses.

掲載誌: J Radiol Prot 2016; 36 (3): 437-455

この論文は、英国で実施された、出生時住居の電力線接近度と小児がんに関する疫学研究から導かれた詳細分析の結果を報告している。それによると、架空送電線に関して先に報告した小児白血病リスク上昇は、診断時年齢の高い小児においては、またリンパ性白血病よりむしろ骨髄白血病においては、やや高めであったこと;出生地域間で差が見られたが明らかな傾向はなかったこと;先の報告した1960年代から2000年代にかけてのリスク低下は、対象となる架空送電線の建設年ではなく、出生もしくはがん発症の暦年に関連していた、と報告している。

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研究の目的(著者による)

Further analyses from an epidemiological study of childhood cancer and residence at birth near high-voltage power lines in the UK were reported. Previous publications on this study are Draper et al. (2005), Kroll et al. (2010), Bunch et al. (2014), Swanson et al. (2014) and Bunch et al. (2015).

詳細情報

1.) Three subgroup analyses that were not included in any of the earlier papers are presented: age of child at diagnosis (0, 1-4, 5-9, and 10-14 years), subtype of leukemia and by region of the country (10 different regions).
2.) The aim was to investigate whether the observed declining risk over time from 1962 to 2008 was linked more strongly to year of birth or year of cancer diagnosis or to year of construction of the relevant power line.
3.) Updated magnetic field calculations were performed for the whole study population.

影響評価項目/リスク推定のタイプ

リスク推定のタイプ: (相対リスク(RR))

ばく露

ばく露評価

ばく露集団

グループ 説明
集団 1 distance of address at birth to nearest power line: 0 - 199 m
集団 2 distance of address at birth to nearest power line: 200 - 599 m
集団 3 distance of address at birth to nearest power line: 600 - 999 m
参照集団 4 distance of address at birth to nearest power line: ≥ 1000 m
集団 5 calculated magnetic flux density: ≥ 0.4 µT
集団 6 calculated magnetic flux density: 0.2 - 0.39 µT
集団 7 calculated magnetic flux density: 0.1 - 0.19 µT
参照集団 8 calculated magnetic flux density: < 0.1 µT

調査対象集団

症例集団

対照集団

調査規模

症例 対照
適格者 57,067 -
評価可能 53,506 66,204

結論(著者による)

1.) The results suggest that the elevated risks for childhood leukaemia that were previously found for overhead power lines may be higher for older age at diagnosis and higher for myeloid leukemia rather than lymphoid leukemia. There are differences across regions of birth but not forming any obvious pattern.
2.) The previously reported decline in risk from the 1960s to the 2000s seems to be linked to year of birth or year of cancer diagnosis rather than year of construction of the relevant power line.
3.) A non-significant reduced risk was observed for magnetic flux densities of ≥ 0.4 µT compared to < 0.1 µT (RR 0.50, CI 0.15-1.62) in comparison to earlier analyses (RR 2.00, CI 0.18-22.04). However, calculated magnetic flux densities of ≥ 0.4 µT were observed only for 4 out of 15920 children with leukemia and 10 of 19608 control children.
The authors draw overall conclusions: Some elevated risks for childhood leukaemia associated with overhead power lines were found. These results seem to suggest that there is a factor that can, in some circumstances, lead to raised leukaemia rates in the vicinity of overhead power lines. This effect can be observed to distances of approximately 600 m for 400 kV and 275 kV power lines and to a lesser distance for 132 kV power lines. It has declined progressively from the 1960s and is now not present at all (RR for residential distances < 200 m compared to ≥ 1000 m for all power lines combined, 1960s: 4.50, 2000s: 0.71). This definitely cannot be the effect of magnetic fields alone, and it seems unlikely that magnetic fields are contributing significantly to the excesses at all. The preferred candidate of the authors remains some link between the presence of the power line and socioeconomic or demographic factors in its vicinity.

研究助成

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