研究のタイプ: 疫学研究 (observational study)

[接触電流ばく露と小児白血病リスク] epidem.

Exposure to electrical contact currents and the risk of childhood leukemia.

掲載誌: Radiat Res 2011; 175 (3): 390-396

この研究は、接触電流ばく露小児白血病リスクとの関連、さらに住宅での接触電流磁界との関係を調査した。この北カリフォルニア小児白血病研究(2000-2007)は、症例245例および対照269例の診断時に居住していた住宅の屋内と屋外において、接触電圧および磁界の測定値を収集した。ロジスティック回帰手法を用いて、年齢、性別、ヒスパニックであるか否か、母親の人種、世帯収入を調整したオッズ比OR)を算出した。その結果、小児白血病と屋内接触電圧レベルの間に統計的に有意な関連は見られなかった(90パーセンタイル値(10.5 mV)を上回るばく露グループにおいて、OR = 0.83、95 %信頼区間(CI):0.45 - 1.54);同様に、屋外接触電圧レベルについては、90パーセンタイル値(291.2 mV)を上回るばく露グループにおいて、OR = 0.89、95 %CI:0.48 - 1.63]、屋内磁界レベルについては、ばく露レベル > 0.20 μTグループにおいて、OR = 0.76、95 %CI:0.30 - 1.93であり、統計的に有意な関連は見られなかった;接触電圧磁界と弱く相関しており、相関係数は、屋内接触電圧でr = 0.10(P = 0.02)、屋外接触電圧でr = 0.15(P = 0.001)であった;総括すると、調査したカリフォルニアの人口集団では、小児白血病接触電流または磁界へのばく露との間に関連の証拠はなかった、と報告している。

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研究の目的(著者による)

A case-control study was conducted in the USA to investigate the association between contact current exposure and the risk of childhood leukemia. Furthermore the relationship between residential contact currents and magnetic fields should be examined.

詳細情報

The hypothesis whether exposure to contact currents might act as a confounder in the reported associations between magnetic fields and childhood leukemia should be tested. Contact currents occur when a person touches conductive surfaces at different potentials and completes a path through which electric current flows within the body. The voltage on a residential water line can produce contact currents in young children while they are bathing provided that they are in contact with a metallic fixture and that the drain is made of conductive material.
Exposure to contact currents and magnetic fields were assessed by 30-minutes measurements inside and outside the homes of the children.

影響評価項目/リスク推定のタイプ

リスク推定のタイプ: (オッズ比(OR))

ばく露

ばく露評価

ばく露集団

グループ 説明
参照集団 1 indoor contact voltage: quartile 1-2 (0.00 - 0.25 mV)
集団 2 indoor contact voltage: quartile 3 (0.25 - 1.50 mV)
集団 3 indoor contact voltage: quartile 4 (≥ 1.50 mV)
参照集団 4 indoor contact voltage: unexposed (90. percentile, < 10.5 mV)
集団 5 indoor contact voltage: exposed (≥ 10.5 mV)
参照集団 6 outdoor contact voltage: quartile 1 (0.00 - 35.8 mV)
集団 7 outdoor contact voltage: quartile 2 (35.8 - 89.7 mV)
集団 8 outdoor contact voltage: quartile 3 (89.7 - 166.8 mV)
集団 9 outdoor contact voltage: quartile 4 (≥ 166.8 mV)
参照集団 10 outdoor contact voltage: unexposed (90. percentile, < 291.2 mV)
集団 11 outdoor contact voltage: exposed (≥ 291.2 mV)
参照集団 12 indoor magnetic field exposure: quartile 1 ( 0 - 0.01 µT)
集団 13 indoor magnetic field exposure: quartile 2 ( 0.01 - 0.02 µT)
集団 14 indoor magnetic field exposure: quartile 3 ( 0.02 - 0.05 µT)
集団 15 indoor magnetic field exposure: quartile 4 (≥ 0.05 µT)
参照集団 16 indoor magnetic field exposure: unexposed (90. percentile, < 0.09 µT)
集団 17 indoor magnetic field exposure: exposed (≥ 0.09 µT)
参照集団 18 indoor magnetic field exposure, a priori cutpoint: ≤ 0.10 µT
集団 19 indoor magnetic field exposure, a priori cutpoint: > 0.10 - ≤ 0.20 µT
集団 20 indoor magnetic field exposure, a priori cutpoint: >0.20 - ≤ 0.30 µT
集団 21 indoor magnetic field exposure, a priori cutpoint: > 0.30 µT

調査対象集団

症例集団

対照集団

調査規模

症例 対照
参加者 245 269
統計学的分析方法: (調整: )

結論(著者による)

No statistically significant associations were observed between childhood leukemia and indoor or outdoor contact voltage levels and indoor magnetic fields. Contact voltage was weakly correlated with magnetic field (correlation coefficients r = 0.10 (P = 0.02) for indoor contact voltage and r = 0.15 (P = 0.001) for outdoor contact voltage).
The authors concluded that in this Califoria population, there was no evidence of an association between childhood leukemia and exposure to contact currents or magnetic fields and a weak correlation between measures of contact current and magnetic fields.

研究助成

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