Abstract
Research data on the biological effects of intermediate-frequency magnetic fields (IF-MF) remain inadequate, and there are no protocols currently exists that can assess the biological effects of electromagnetic fields similar to those used with the OECD guidelines for chemicals. IF-MF <100 kHz have a dominant stimulatory effect, which has raised concerns about their effects on neurological disorders. The purpose of this study was to investigate methods for detecting pain in response to IF-MF exposure and to establish a standardized protocol for electromagnetic field pain assessment for use in various environments. The von Frey test, which can assess foot pain, was performed using the partial sciatic nerve ligation (PSL) model, which is a nerve hypersensitivity and allodynia model, together with IF-MF-exposed, sham-exposed, and no-treatment (control) groups. Significant changes were observed at all postoperative measurement points in the PSL group, whereas no significant differences were present among the other groups. In addition, gene expression analysis for four inflammation-related factors (P2rx4, Ccl2, Irf8, and Iba1) was performed using real-time quantitative PCR in the sciatic nerve on postoperative day 15 after exposure. The expression of these genes was significantly upregulated in the PSL group but was unchanged in the remaining three groups. These results confirm that IF-MF exposure (1 hr/day), which is 2.3 times higher than the basic restriction for occupational exposure according to the ICNIRP guidelines, does not cause pain and that these detection methods with positive controls are effective as pain assessment methods for IF-MF exposure.
