Abdollahzadeh S, Hammond S K, Schenker M B
Department of Family and Community Medicine, University of Massachusetts Medical Center, Worcester 01655, USA.
Bioelectromagnetics. 1996;17(5):406-10. doi: 10.1002/(SICI)1521-186X(1996)17:5<406::AID-BEM8>3.0.CO;2-7.
In studies investigating adverse reproductive outcomes associated with video display terminal (VDT) usage, amounts of time spent in front of a VDT or magnetic field (MF) levels in front of the VDT are used as surrogate measures of subject's MF exposure. However, the relevance of such surrogates to actual exposures has not been demonstrated, and the validity of the use of such measures as a surrogate for the actual MF exposure is only speculative. This study examines 1) measurements of MFs at frequencies of approximately 30-1000 Hz at a fixed distance from the VDTs, 2) reported hours of VDT use, and 3) reported distance between the VDT and the subject's waist as surrogate measures for the average MF exposure level of a VDT user during one 8 h workday. The results showed a weak correlation between the average exposure level of a VDT user and the MF 46 cm from a VDT (R = 0.52, n = 67, P < 0.001). This study showed no association between self-reported hours of VDT usage, or self-reported distance between waist and VDT, and the average MF exposures. Moreover, individuals' average MF exposures did not seem to be affected by other variables, such as position of a VDT on the desk, hours of desk use, and the VDT type (color vs. monochrome). These findings indicate that VDT exposures within office settings are complex and cannot be easily predicted by surrogates.
在调查与视频显示终端（VDT）使用相关的不良生殖结局的研究中，在VDT前花费的时间量或VDT前的磁场（MF）水平被用作受试者MF暴露的替代指标。然而，此类替代指标与实际暴露的相关性尚未得到证实，并且将此类指标用作实际MF暴露替代指标的有效性仅是推测性的。本研究考察了：1）在距VDT固定距离处对约30 - 1000 Hz频率的MF进行测量；2）报告的VDT使用小时数；3）报告的VDT与受试者腰部之间的距离，作为VDT使用者在一个8小时工作日期间平均MF暴露水平的替代指标。结果显示，VDT使用者的平均暴露水平与距VDT 46厘米处的MF之间存在弱相关性（R = 0.52，n = 67，P < 0.001）。本研究表明，自我报告的VDT使用小时数或自我报告的腰部与VDT之间的距离与平均MF暴露之间无关联。此外，个体的平均MF暴露似乎不受其他变量的影响，如VDT在桌面上的位置、桌面使用小时数以及VDT类型（彩色与单色）。这些发现表明，办公环境中的VDT暴露情况复杂，难以通过替代指标轻易预测。
