The effects of long-term exposure to extremely low-frequency magnetic fields on bone formation in ovariectomized rats.

The effects of long-term extremely low-frequency magnetic field (ELF-MF) exposure on bone formation and biochemical markers were investigated in ovariectomized rats. Sixty mature female Sprague-Dawley rats were randomly divided into four different groups (n = 15): (i) unexposed control (CTL); (ii) ovariectomized only (OVX); (iii) non-ovariectomized, exposed (SHAM + ELF-MF); and (iv) ovariectomized, exposed (OVX + ELF-MF). The third and fourth groups were exposed to 1.5 mT ELF-MF for 4 h a day for 6 months. Bone mineral density (BMD) was determined using dual energy X-ray absorption (DEXA) measurements. The formation and resorption of bone were evaluated using bone-specific alkaline phosphatase (BAP), osteocalcin, osteoprotogerin, and N-telopeptide. After 6 months of ELF-MF therapy, BMD values were significantly lower in the OVX group and higher in the OVX + ELF-MF and SHAM + ELF-MF groups than they were before therapy (P < 0.001). Although there was no significant difference in BMD values among the groups before therapy, the BMD values increased significantly after 6 months in the OVX + ELF-MF and SHAM + ELF-MF groups and were reduced in the OVX group compared to the CTL group (P < 0.001). The concentrations of BAP, osteocalcin, osteoprotogerin, and N-telopeptide in the three experimental groups also changed in a significant way compared to the CTL group. The results of the present study suggest that osteoporosis can be inhibited by ELF-MF stimulation treatments. It was also concluded that ELF-MF may be useful in the prevention of osteoporosis in ovariectomized rats.

Effects of extremely low frequency electromagnetic fields on hematologic and immunologic parameters in welders.

BACKGROUND: Electric arc welding is known to cause considerable exposure to extremely low frequency magnetic fields. Although some studies of exposure to magnetic fields and epidemiologic studies have included groups of welders, typically little information is available concerning the hematologic and immunologic effects of ELF electromagnetic fields on welders. Therefore, the aim of the present study is to investigate whether or not extremely low frequency electromagnetic fields (ELF EMF) emitted from electric arc welding affect some hematologic and immunologic parameters of welders. METHODS: The study was carried out on 16 male welders and 14 healthy males between 20 and 40 years of age from the same geographic area and with similar life styles. The following hematologic and immunologic parameters were measured in both groups: red blood cells (RBC); hemoglobin (Hgb); hematocrit (Hct); platelets (Plt); total white blood cells (WBC); neutrophils; lymphocytes; eosinophils; and CD3, CD4, CD8, and CD4/CD8. RESULTS: Some of the hematologic and immunologic parameters under investigation were similar in both groups. Although T lymphocyte surface antigens, such as levels of CD4 and CD8(,) were found to be lower in the welders than in the control subjects (p <0.001, p <0.05), the hematocrit levels of the welders were found to be higher than those of the control subjects (p <0.05). However, the differences observed were not clinically significant. ELF electromagnetic field intensities in the welding areas varied between 0.10 and 0.25 mT. CONCLUSIONS: These results suggest that ELF electromagnetic fields do not affect the hematologic and immunologic parameters of welders.