Adverse and beneficial effects in Chinese hamster lung fibroblast cells following radiofrequency exposure

Study snapshot

Abstract

Adverse and beneficial effects in Chinese hamster lung fibroblast cells following radiofrequency exposure Sannino A, Zeni O, Romeo S, Massa R, Scarfi MR. Adverse and beneficial effects in Chinese hamster lung fibroblast cells following radiofrequency exposure. Bioelectromagnetics. 2017 Jan 10. doi: 10.1002/bem.22034. Abstract In this study, the effect of radiofrequency (RF) exposure to 1950 MHz, Universal Mobile Telecommunication System signal, was investigated in Chinese hamster lung fibroblast cell line (V79). Genotoxic and cytotoxic effects of 20-h exposure at specific absorption rate (SAR) values from 0.15 W/kg to 1.25 W/kg were measured by means of cytokinesis-block micronucleus (MN) assay. Exposure was carried out blinded under strictly controlled conditions of dosimetry and temperature. The effect of RF exposure alone at four SAR values was tested, that is, 0.15, 0.3, 0.6, and 1.25 W/kg. A statistically significant increase in MN frequency was found in cultures exposed to 0.15 and 0.3 W/kg (P < 0.05) compared to sham-exposed ones, in the absence of cytotoxicity. SAR values of 0.6 and 1.25 W/kg did not exert any effect. Moreover, to evaluate the ability of RF to exert protective effects with respect to a chemical mutagen, cell cultures were also pre-exposed for 20 h at 0.3 or 1.25 W/kg, and then treated with 500 ng/ml of mitomycin-C (MMC). A significant reduction in the frequency of MN was detected in cultures pre-exposed to 1.25 W/kg compared to cultures treated with MMC alone (P < 0.05), indicating induction of adaptive response. Such a decrease was not induced by pre-exposure at 0.3 W/kg SAR. Taken together, our results indicated that V79 is a sensitive cell model to evidence either adverse or beneficial effects of RF exposure, depending on experimental conditions applied. Excerpts The results presented here indicated lack of MN increase in cultures exposed for 20 h to 1950 MHz, UMTS signal, at SAR values of 0.6 and 1.25 W/kg. On the contrary, exposure to 0.15 and 0.3 W/kg SAR resulted in a statistically significant increase in MN frequency (P < 0.05), compared to sham controls. Concerning 0.3 W/kg, such an increase was also detected in three more independent experiments, carried out to evaluate RF-induced AR (Table 3). On the whole, an average MN increase of 55% was gained on seven independent experiments, in absence of cytotoxicity, although some experimental variability was recorded. The observed effect was non-thermal, since chromosomal damage has been recorded at 0.15 and 0.3 W/kg SAR but not at higher values (0.6 and 1.25 W/kg).... Consistent with results presented here, Xu et al. [2013] identified Chinese hamster fibroblasts as a sensitive cell model in a comparative study where different cell types were exposed to RF. The authors exposed six cell types to 1800 MHz, GSM, 3 W/kg SAR, and 24 h exposure (5 min on/10 min off cycles), resulting in a significant increase in DNA damage, evaluated as gamma foci formation in Chinese hamster lung cells and human skin fibroblasts, but not in other cell types tested [Xu et al., 2013]. The dependency of the effect on cell type has been also reported by other authors, who demonstrated that the same RF exposure conditions resulted in affecting certain cell types but not others, when protein expression [Sanchez et al., 2006; Zimmerman et al., 2012; Lu et al., 2014], enzyme activity [Hoyto et al., 2007], oxidative stress [Lantow et al., 2006], or cell proliferation [Trillo et al., 2011] were investigated. We do not have an explanation for the chromosomal damage detected in this investigation. Rather, due to dependence of the effect on SAR level, our findings seem in agreement with the theory of "window" effects, proposed to explain several non-linear results in bioelectromagnetic research [Postow and Swicord, 1986]. Effects have been reported at some frequencies but not at others, or at lower but not at higher SAR levels of the same frequency, or at certain modulations but not at others, either in vivo or in vitro [Dutta et al., 1992; Panagopoulos and Margaritis, 2010a,b]. ncbi.nlm.nih.gov

Main findings

After 20 h UMTS 1950 MHz exposure, micronucleus frequency increased significantly versus sham at SAR 0.15 and 0.3 W/kg (P < 0.05) without cytotoxicity, while no effect was observed at 0.6 or 1.25 W/kg. In an adaptive-response experiment, pre-exposure at 1.25 W/kg (but not 0.3 W/kg) reduced micronucleus frequency after mitomycin-C treatment compared with mitomycin-C alone (P < 0.05).

Outcomes measured

• Genotoxicity (micronucleus frequency; cytokinesis-block micronucleus assay)
• Cytotoxicity
• Adaptive response/protective effect against chemical mutagen (mitomycin-C)

Limitations

• Sample size not reported in provided abstract/metadata
• In vitro cell model; generalizability to humans not addressed in provided abstract
• Mechanism not explained in provided abstract; authors note they do not have an explanation for observed chromosomal damage

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