Work Environment Research Group, National Institute of Occupational Safety and Health, Kawasaki, Japan.
Department of Systems Design, Tokyo Metropolitan University, Hachioji, Japan.
Front Public Health. 2022 Jul 28;10:870784. doi: 10.3389/fpubh.2022.870784. eCollection 2022.
To assess exposure levels to electromagnetic fields (EMFs) among library workers in Japan, focusing on co-exposure to intermediate-frequency EMF (IF-EMF) and pulsed EMF, to propose a new epidemiological research methodology.
The evaluated exposure sources were an electromagnetic type-electronic article surveillance gate (EM-EAS, IF-EMF (operating frequency 220 Hz-14 kHz)) and an activator/deactivator of anti-theft tags termed as "book check unit" (BCU, pulsed EMF). Short-term exposures were: (E1) whole-body exposure from the EAS gate when sitting within 3 m; (E2) local exposure to transient IF-EMF while passing through or beside the EAS gate; and (E3) local exposure to a pulsed magnetic field on BCU use. E1-E3 were evaluated based on exposure levels relative to magnetic flux density at the occupational reference level (RL; E1) or as per occupational basic restrictions (BR; E2 and E3) delineated by the International Commission on Non-Ionizing Radiation Protection (ICNIRP) 2010 guidelines. Exposure indices based on mid-term exposure (D1-D3), assuming exposure according to employment on a weekly basis, were used to assess exposure in actual working conditions. D1 represents continuous exposure from an EAS gate when sitting within 3 m of the gate. D2 and D3 represent repeated transient exposures occurring during gate pass or on the operation of a BCU. A link to a web-based questionnaire was distributed to librarians working at all libraries where the authors had mailed institutional questionnaires (4,073 libraries). Four exposure patterns were defined according to various exposure scenarios.
We obtained information on exposure parameters and working conditions from the 548 completed questionnaires. The ICNIRP guideline levels were not exceeded in any of the E1-E3 scenarios. Median of the D1 (% ICNIRP RL × hour/week) was 1, and >85% respondents had values <10. However, the maximum value was 513. Altogether, these results indicate that continuous exposure was low in most cases. The same tendency was observed regarding repeated transient exposure from EM-EAS gates (i.e., the median value for D2 (% ICNIRP BR × gate pass) was 5). However, there were several cases in which D1 and D2 values were >10 times the median. The median of D3 (% ICNIRP BR × BCU operation) was 10, and most respondents' D3 values were greater than their D2 values, although the derived results depended on the assumptions made for the estimation.
We conducted an assessment of combined exposures to IF-EMF and pulsed EMF among library workers in Japan by evaluating both short-term exposures (E1-E3) and exposure indices based on mid-term exposures (D1-D3) assuming actual working conditions per questionnaire results. These results provide useful information for future epidemiological studies.
评估日本图书馆工作人员接触电磁场（EMF）的水平，重点关注中频 EMF（IF-EMF）和脉冲 EMF 的共暴露情况，并提出一种新的流行病学研究方法。
评估的暴露源包括电磁式电子物品监控门（EM-EAS，IF-EMF（工作频率 220 Hz-14 kHz））和防盗标签的激活/去激活器，称为“图书检查单元”（BCU，脉冲 EMF）。短期暴露包括：（E1）坐在 3 m 范围内的 EAS 门内时全身暴露；（E2）通过或在 EAS 门旁边时局部暴露于瞬态 IF-EMF；（E3）在使用 BCU 时局部暴露于脉冲磁场。E1-E3 的评估基于相对于职业参考水平（RL；E1）的磁通密度的暴露水平，或基于国际非电离辐射防护委员会（ICNIRP）2010 年指南规定的职业基本限制（BR；E2 和 E3）。基于中期暴露（D1-D3）的暴露指数，假设每周根据就业情况进行暴露，用于评估实际工作条件下的暴露情况。D1 表示坐在离门 3 m 范围内的 EAS 门时的连续暴露。D2 和 D3 表示在门通过或 BCU 操作期间发生的重复瞬态暴露。向作者已向其邮寄机构问卷的所有图书馆的图书馆员分发了一个基于网络的问卷链接（4073 个图书馆）。根据各种暴露情况定义了四种暴露模式。
我们从 548 份完成的问卷中获得了暴露参数和工作条件的信息。在任何 E1-E3 情况下，ICNIRP 准则水平均未超标。D1（% ICNIRP RL×小时/周）的中位数为 1，超过 85%的受访者的值<10。然而，最大值为 513。总的来说，这些结果表明大多数情况下连续暴露较低。从 EM-EAS 门的重复瞬态暴露来看，也存在同样的趋势（即，D2（% ICNIRP BR×门通过）的中位数为 5）。然而，在某些情况下，D1 和 D2 的值是中位数的 10 倍以上。D3（% ICNIRP BR×BCU 操作）的中位数为 10，大多数受访者的 D3 值大于其 D2 值，尽管推导结果取决于对估计的假设。
我们通过评估短期暴露（E1-E3）和基于中期暴露（D1-D3）的暴露指数，评估了日本图书馆工作人员接触 IF-EMF 和脉冲 EMF 的综合暴露情况，假设结果基于问卷调查结果的实际工作条件。这些结果为未来的流行病学研究提供了有用的信息。
