Vijayalaxmi, Logani, M. K., Bhanushali, A., Ziskin, M. C. and Prihoda, T. J. Micronuclei in Peripheral Blood and Bone Marrow Cells of Mice Exposed to 42 GHz Electromagnetic Millimeter Waves. Radiat. Res. 161, 341–345 (2004).The genotoxic potential of 42.2 ± 0.2 GHz electromagnetic millimeter-wave radiation was investigated in adult male BALB/c mice. The radiation was applied to the nasal region of the mice for 30 min/day for 3 consecutive days. The incident power density used was 31.5 ± 5.0 mW/cm2. The peak specific absorption rate was calculated as 622 ± 100 W/kg. Groups of mice that were injected with cyclophosphamide (15 mg/kg body weight), a drug used in the treatment of human malignancies, were also included to determine if millimeter-wave radiation exposure had any influence on drug-induced genotoxicity. Concurrent sham-exposed and untreated mice were used as controls. The extent of genotoxicity was assessed from the incidence of micronuclei in polychromatic erythrocytes of peripheral blood and bone marrow cells collected 24 h after treatment. The results indicated that the incidence of micronuclei in 2000 polychromatic erythrocytes was not significantly different among untreated, millimeter wave-exposed, and sham-exposed mice. The group mean incidences were 6.0 ± 1.6, 5.1 ± 1.5 and 5.1 ± 1.3 in peripheral blood and 9.1 ± 1.1, 9.3 ± 1.6 and 9.1 ± 1.6 in bone marrow cells, respectively. Mice that were injected with cyclophosphamide exhibited significantly increased numbers of micronuclei, 14.6 ± 2.7 in peripheral blood and 21.3 ± 3.9 in bone marrow cells (P< 0.0001). The drug-induced micronuclei were not significantly different in millimeter wave-exposed and sham-exposed mice; the mean incidences were 14.3 ± 2.8 and 15.4 ± 3.0 in peripheral blood and 23.5 ± 2.3 and 22.1 ± 2.5 in bone marrow cells, respectively. Thus there was no evidence for the induction of genotoxicity in the peripheral blood and bone marrow cells of mice exposed to electromagnetic millimeter-wave radiation. Also, millimeter-wave radiation exposure did not influence cyclophosphamide-induced micronuclei in either type of cells.
Vijayalaxmi and Prihoda, T. J. Genetic Damage in Mammalian Somatic Cells Exposed to Radiofrequency Radiation: A Meta-analysis of Data from 63 Publications (1990–2005). Radiat. Res. 169, 561–574 (2008).During the last several decades, numerous researchers have examined the potential of in vitro and/or in vivo exposure of radiofrequency (RF) radiation to damage the genetic material in mammalian somatic cells. A meta-analysis of reported data was conducted to obtain a quantitative estimate (with 95% confidence intervals) of genotoxicity in RF-radiation-exposed cells compared with sham-exposed/unexposed control cells. The extent of genotoxicity was assessed for various end points, including single- and double-strand breaks in the DNA, incidence of chromosomal aberrations, micronuclei and sister chromatid exchanges. Among the several variables in the experimental protocols used in individual investigations, the influence of three specific variables related to RF-radiation exposure characteristics was examined in the meta-analysis: frequency, specific absorption rate, and exposure as continuous-wave, pulsed-wave and occupationally exposed/cell phone users. The overall data indicated that (1) the difference between RF-radiation-exposed and sham-/unexposed controls as well as the effect size or standardized mean difference due to RF-radiation exposure was small with very few exceptions; (2) at certain RF radiation exposure conditions, there were statistically significant increases in genotoxicity for some end points; and (3) the mean indices for chromosomal aberrations and micronuclei in RF-radiation-exposed and sham-/unexposed controls were within the spontaneous levels reported in the historical database. Considerable evidence for publication bias was found in the meta-analysis.
Four specific quality control measures were used to determine the quality of 225 publications on the genetic damage in mammalian cells exposed in vitro and in vivo to RF energy and they were as follows. (i) 'Blind' collection/analysis of the data to eliminate individual/observer 'bias'. (ii) Adequate description of 'dosimetry' for independent replication/confirmation. (iii) Inclusion of 'positive controls' to confirm the outcomes. (iv) Inclusion of 'sham-exposed controls' which are more appropriate to compare the data with those in RF exposure conditions. In addition, meta-analysis of the data reported from 2160 tests was used to obtain the 'd' values or effect size or the standardized mean difference between the experimental and control cells. The relationship between d values and the above-mentioned quality control measures was ascertained. In addition, the correlation between the quality control measures and the conclusions (no significant difference between the cells exposed to RF energy and control cells; increased damage in former cells compared with the latter; increased, no significant difference and decreased damage in cells exposed to RF energy in the same experiment; decreased damage in cells exposed to RF energy) reported in the publications was examined.
To investigate the extent of damage in nucleated cells in peripheral blood of healthy human volunteers exposed to a whole-body 60 Hz, 200 microT magnetic field. In this study, 10 male and 10 female healthy human volunteers received a 4 h whole-body exposure to a 200 microT, 60 Hz magnetic field. In addition, five males and five females were treated in a similar fashion, but were exposed to sham conditions. For each subject, a blood sample was obtained prior to the exposure period and aliquots were used as negative- (pre-exposure) and positive- [1.5 Gray (Gy) (60)Cobalt ((60)Co) gamma-irradiation] controls. At the end of the 4 h exposure period, a second blood sample was obtained. The extent of DNA damage was assessed in peripheral human blood leukocytes from all samples using the alkaline comet assay. To detect possible clastogenic effects, the incidence of micronuclei was assessed in phytohemagglutinin (PHA)-stimulated lymphocytes using the cytokinesis-block micronucleus assay. There was no evidence of either increased DNA damage, as indicated by the alkaline comet assay, or increased incidence of micronuclei (MN) in the magnetic field exposed group. However, an in vitro exposure of 1.5 Gy gamma-irradiation caused a significant increase in both DNA damage and MN induction. This study found no evidence that an acute, whole-body exposure to a 200 microT, 60 Hz magnetic field for 4 hours could cause DNA damage in human blood.
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