I. Lagroye

Measurement of DNA damage and apoptosis in Molt-4 cells after in vitro exposure to radiofrequency radiation.

Abstract Hook, G. J., Zhang, P., Lagroye, I., Li, L., Higashikubo, R., Moros, E. G., Straube, W. L., Pickard, W. F., Baty, J. D. and Roti Roti, J. L. Measurement of DNA Damage and Apoptosis in Molt-4 Cells after In Vitro Exposure to Radiofrequency Radiation. Radiat. Res. 161, 193–200 (2004). To determine whether exposure to radiofrequency (RF) radiation can induce DNA damage or apoptosis, Molt-4 T lymphoblastoid cells were exposed with RF fields at frequencies and modulations of the type used by wireless communication devices. Four types of frequency/modulation forms were studied: 847.74 MHz code-division multiple-access (CDMA), 835.62 MHz frequency-division multiple-access (FDMA), 813.56 MHz iDEN® (iDEN), and 836.55 MHz time-division multiple-access (TDMA). Exponentially growing cells were exposed to RF radiation for periods up to 24 h using a radial transmission line (RTL) exposure system. The specific absorption rates used were 3.2 W/kg for CDMA and FDMA, 2.4 or 24 mW/kg for iDEN, and 2.6 or 26 mW/kg for TDMA. The temperature in the RTLs was maintained at 37°C ± 0.3°C. DNA damage was measured using the single-cell gel electrophoresis assay. The annexin V affinity assay was used to detect apoptosis. No statistically significant difference in the level of DNA damage or apoptosis was observed between sham-treated cells and cells exposed to RF radiation for any frequency, modulation or exposure time. Our results show that exposure of Molt-4 cells to CDMA, FDMA, iDEN or TDMA modulated RF radiation does not induce alterations in level of DNA damage or induce apoptosis.

In vitro and in vivo genotoxicity of radiofrequency fields

There has been growing concern about the possibility of adverse health effects resulting from exposure to radiofrequency radiations (RFR), such as those emitted by wireless communication devices. Since the introduction of mobile phones many studies have been conducted regarding alleged health effects but there is still some uncertainty and no definitive conclusions have been reached so far. Although thermal effects are well understood they are not of great concern as they are unlikely to result from the typical low-level RFR exposures. Concern rests essentially with the possibility that RFR-exposure may induce non-thermal and/or long-term health effects such as an increased cancer risk. Consequently, possible genetic effects have often been studied but with mixed results. In this paper we review the data on alleged RFR-induced genetic effects from in vitro and in vivo investigations as well as from human cytogenetic biomonitoring surveys. Attention is also paid to combined exposures of RFR with chemical or physical agents. Again, however, no entirely consistent picture emerges. Many of the positive studies may well be due to thermal exposures, but a few studies suggest that biological effects can be seen at low levels of exposure. Overall, however, the evidence for low-level genotoxic effects is very weak.

Effects of radiofrequency electromagnetic fields on the human nervous system

The effects of exposure to radiofrequency electromagnetic fields (EMF), specifically related to the use of mobile telephones, on the nervous system in humans have been the subject of a large number of experimental studies in recent years. There is some evidence of an effect of exposure to a Global System for Mobile Telecommunication (GSM)-type signal on the spontaneous electroencephalogram (EEG). This is not corroborated, however, by the results from studies on evoked potentials. Although there is some evidence emerging that there may be an effect of exposure to a GSM-type signal on sleep EEG, results are still variable. In summary, exposure to a GSM-type signal may result in minor effects on brain activity, but such changes have never been found to relate to any adverse health effects. No consistent significant effects on cognitive performance in adults have been observed. If anything, any effect is small and exposure seems to improve performance. Effects in children did not differ from those in healthy adults. Studies on auditory and vestibular function are more unequivocal: neither hearing nor the sense of balance is influenced by short-term exposure to mobile phone signals. Subjective symptoms over a wide range, including headaches and migraine, fatigue, and skin itches, have been attributed to various radiofrequency sources both at home and at work. However, in provocation studies a causal relation between EMF exposure and symptoms has never been demonstrated. There are clear indications, however, that psychological factors such as the conscious expectation of effect may play an important role in this condition.

Mouse Strain Susceptibility to Trypanosome Infection: An Arginase-Dependent Effect

We previously reported that macrophage arginase inhibits NO-dependent trypanosome killing in vitro and in vivo. BALB/c and C57BL/6 mice are known to be susceptible and resistant to trypanosome infection, respectively. Hence, we assessed the expression and the role of inducible NO synthase (iNOS) and arginase in these two mouse strains infected with Trypanosoma brucei brucei. Arginase I and arginase II mRNA expression was higher in macrophages from infected BALB/c compared with those from C57BL/6 mice, whereas iNOS mRNA was up-regulated at the same level in both phenotypes. Similarly, arginase activity was more important in macrophages from infected BALB/c vs infected C57BL/6 mice. Moreover, increase of arginase I and arginase II mRNA levels and of macrophage arginase activity was directly induced by trypanosomes, with a higher level in BALB/c compared with C57BL/6 mice. Neither iNOS expression nor NO production was stimulated by trypanosomes in vitro. The high level of arginase activity in T. brucei brucei-infected BALB/c macrophages strongly inhibited macrophage NO production, which in turn resulted in less trypanosome killing compared with C57BL/6 macrophages. NO generation and parasite killing were restored to the same level in BALB/c and C57BL/6 macrophages when arginase was specifically inhibited with Nω-hydroxy-nor-l-arginine. In conclusion, host arginase represents a marker of resistance/susceptibility to trypanosome infections.

Systematic review of wireless phone use and brain cancer and other head tumors

We conducted a systematic review of scientific studies to evaluate whether the use of wireless phones is linked to an increased incidence of the brain cancer glioma or other tumors of the head (meningioma, acoustic neuroma, and parotid gland), originating in the areas of the head that most absorb radiofrequency (RF) energy from wireless phones. Epidemiology and in vivo studies were evaluated according to an agreed protocol; quality criteria were used to evaluate the studies for narrative synthesis but not for meta-analyses or pooling of results. The epidemiology study results were heterogeneous, with sparse data on long-term use (≥ 10 years). Meta-analyses of the epidemiology studies showed no statistically significant increase in risk (defined as P < 0.05) for adult brain cancer or other head tumors from wireless phone use. Analyses of the in vivo oncogenicity, tumor promotion, and genotoxicity studies also showed no statistically significant relationship between exposure to RF fields and genotoxic damage to brain cells, or the incidence of brain cancers or other tumors of the head. Assessment of the review results using the Hill criteria did not support a causal relationship between wireless phone use and the incidence of adult cancers in the areas of the head that most absorb RF energy from the use of wireless phones. There are insufficient data to make any determinations about longer-term use (≥ 10 years).

Measurement of DNA Damage in Mammalian Cells Exposed In Vitro to Radiofrequency Fields at SARs of 3–5 W/kg

Abstract Li, L., Bisht, K. S., LaGroye, I., Zhang, P., Straube, W. L., Moros, E. G. and Roti Roti, J. L. Measurement of DNA Damage in Mammalian Cells Exposed In Vitro to Radiofrequency Fields at SARs of 3–5 W/kg. Radiat. Res. 156, 328–332 (2001). In the present study, we determined whether exposure of mammalian cells to 3.2–5.1 W/kg specific absorption rate (SAR) radiofrequency fields could induce DNA damage in murine C3H 10T½ fibroblasts. Cell cultures were exposed to 847.74 MHz code-division multiple access (CDMA) and 835.62 frequency-division multiple access (FDMA) modulated radiations in radial transmission line (RTL) irradiators in which the temperature was regulated to 37.0 ± 0.3°C. Using the alkaline comet assay to measure DNA damage, we found no statistically significant differences in either comet moment or comet length between sham-exposed cells and those exposed for 2, 4 or 24 h to CDMA or FDMA radiations in either exponentially growing or plateau-phase cells. Further, a 4-h incubation after the 2-h exposure resulted in no significant changes in comet moment or comet length. Our results show that exposure of cultured C3H 10T½ cells at 37°C CDMA or FDMA at SAR values of up to 5.1 W/kg did not induce measurable DNA damage.

Measurement of DNA damage after acute exposure to pulsed-wave 2450 MHz microwaves in rat brain cells by two alkaline comet assay methods

Purpose: To investigate the effect of 2450 MHz pulsed‐wave microwaves on the induction of DNA damage in brain cells of exposed rats and to discover whether proteinase K is needed to detect DNA damage in the brain cells of rats exposed to 2450 MHz microwaves. Materials and methods: Sprague–Dawley rats were exposed to 2450 MHz pulsed‐wave microwaves and sacrificed 4 h after a 2‐h exposure. Rats irradiated whole‐body with 1 Gy 137Cs were included as positive controls. DNA damage was assayed by two variants of the alkaline comet assay on separate aliquots of the same cell preparation. Results: Significant DNA damage was observed in the rat brain cells of rats exposed to γ‐rays using both versions of the alkaline comet assay independent of the presence or absence of proteinase K. However, neither version of the assay could detect any difference in comet length and/or normalized comet moment between sham‐ and 2450 MHz pulsed‐wave microwave‐exposed rats, regardless of the inclusion or omission of proteinase K in the comet assay. Conclusions: No DNA damage in brain cells was detected following exposure of rats to 2450 MHz microwaves pulsed‐wave at a specific absorption rate of 1.2 W kg−1 regardless of whether or not proteinase K was included in the assay. Thus, the results support the conclusion that low‐level 2450 MHz pulsed‐wave microwave exposures do not induce DNA damage detectable by the alkaline comet assay.

Radiosensitization of heat resistant human tumour cells by 1 hour at 41.1°C and its effect on DNA repair

The present study was undertaken to determine if short duration (1-2h), moderate hyperthermia (41.1°C) could radiosensitize human tumour cells. It was found that moderate hyperthermia (41.1°C), for as little as 1h, can radiosensitize heat resistant human adenocarcinoma cells, NSY42129 (NSY), provided the cells are irradiated 15min prior to the end of the heat exposure. Analysis of the survival data showed a 2.5-3-fold increase in the f parameter with no significant change in the g parameter of the survival curve, implying that the cells had become more susceptible to killing by single radiation energy deposition events as opposed to lethal events that require an interaction between two separate energy deposition events. 41.1°C hyperthermia did not affect the induction or repair of alkaline labile DNA damage in a way that correlated with radiosensitivity. In contrast, heat-induced changes in the induction of micronuclei by radiation correlated with changes in cell killing. Therefore, the effect of 41.1°C hyperthermia on the intracellular localization of the DNA double strand break repair protein, Mre11, was measured using in situ immunofluorescence and immunoblotting of soluble and insoluble cellular fractions. The results showed that Mre11 delocalizes from the nucleus as a function of time at 41.1°C. It was then determined if 41.1°C hyperthermia altered the association of Mre11 with its functional partner, Rad50. A significant decrease in the amount of Rad50 recovered with Mre11 occurred under the experimental conditions that produced significant radiosensitization. These results are consistent with the possibility that the heat-induced perturbation in Mre11 localization and its radiation-induced association with Rad50 contributes to an increase in radiosensitivity.

Measurements of Alkali-Labile DNA Damage and Protein–DNA Crosslinks after 2450 MHz Microwave and Low-Dose Gamma Irradiation In Vitro

Abstract Lagroye, I., Hook, G. J., Wettring, B. A., Baty, J. D., Moros, E. G., Straube, W. L. and Roti Roti, J. L. Measurements of Alkali-Labile DNA Damage and Protein–DNA Crosslinks after 2450 MHz Microwave and Low-Dose Gamma Irradiation In Vitro. Radiat. Res. 161, 201–214 (2004). In vitro experiments were performed to determine whether 2450 MHz microwave radiation induces alkali-labile DNA damage and/or DNA–protein or DNA–DNA crosslinks in C3H 10T½ cells. After a 2-h exposure to either 2450 MHz continuous-wave (CW) microwaves at an SAR of 1.9 W/kg or 1 mM cisplatinum (CDDP, a positive control for DNA crosslinks), C3H 10T½ cells were irradiated with 4 Gy of γ rays (137Cs). Immediately after γ irradiation, the single-cell gel electrophoresis assay was performed to detect DNA damage. For each exposure condition, one set of samples was treated with proteinase K (1 mg/ml) to remove any possible DNA–protein crosslinks. To measure DNA–protein crosslinks independent of DNA–DNA crosslinks, we quantified the proteins that were recovered with DNA after microwave exposure, using CDDP and γ irradiation, positive controls for DNA–protein crosslinks. Ionizing radiation (4 Gy) induced significant DNA damage. However, no DNA damage could be detected after exposure to 2450 MHz CW microwaves alone. The crosslinking agent CDDP significantly reduced both the comet length and the normalized comet moment in C3H 10T½ cells irradiated with 4 Gy γ rays. In contrast, 2450 MHz microwaves did not impede the DNA migration induced by γ rays. When control cells were treated with proteinase K, both parameters increased in the absence of any DNA damage. However, no additional effect of proteinase K was seen in samples exposed to 2450 MHz microwaves or in samples treated with the combination of microwaves and radiation. On the other hand, proteinase K treatment was ineffective in restoring any migration of the DNA in cells pretreated with CDDP and irradiated with γ rays. When DNA–protein crosslinks were specifically measured, we found no evidence for the induction of DNA–protein crosslinks or changes in amount of the protein associated with DNA by 2450 MHz CW microwave exposure. Thus 2-h exposures to 1.9 W/ kg of 2450 MHz CW microwaves did not induce measurable alkali-labile DNA damage or DNA–DNA or DNA–protein crosslinks.

Rat fertility and embryo fetal development: Influence of exposure to the Wi-Fi signal

In recent decades, concern has been growing about decreasing fecundity and fertility in the human population. Exposure to non-ionizing electromagnetic fields (EMF), especially radiofrequency (RF) fields used in wireless communications has been suggested as a potential risk factor. For the first time, we evaluated the effects of exposure to the 2450MHz Wi-Fi signal (1h/day, 6days/week) on the reproductive system of male and female Wistar rats, pre-exposed to Wi-Fi during sexual maturation. Exposure lasted 3 weeks (males) or 2 weeks (females), then animals were mated and couples exposed for 3 more weeks. On the day before delivery, the fetuses were observed for lethality, abnormalities, and clinical signs. In our experiment, no deleterious effects of Wi-Fi exposure on rat male and female reproductive organs and fertility were observed for 1h per days. No macroscopic abnormalities in fetuses were noted, even at the critical level of 4W/kg.