Lack of promotion of 7,12-dimethylbenz[a]anthracene-initiated mouse skin carcinogenesis by 1.5 GHz electromagnetic near fields

Abstract

The effects of 1.5 GHz electromagnetic near fields of time division multiple access (TDMA) signal for the Personal Digital Cellular, Japanese cellular telephone standard (PDC) used for cellular phones, on mouse skin carcinogenesis initiated by 7,12-dimethylbenz[a]anthracene (DMBA) were examined. Ten-week-old ICR female mice were treated with a single application of DMBA on shaved dorsal skin by painting at a concentration of 100 microg/100 microl acetone per mouse. One week later, mice were divided into four groups, receiving electromagnetic near fields exposure (DMBA-EMF), sham-exposure (DMBA-Sham), 12-O-tetradecanoylphorbol-13-acetate (TPA, 4 microg /200 microl acetone/mouse), as a positive control (DMBA-TPA), and no-treatment (DMBA-Control). EMF near fields exposure conditions were as follows: skin local peak specific absorption rate (SAR) 2.0 W/kg, whole body average SAR 0.084 W/kg (ratio of peak to average SAR is 24), 90 min a day, 5 days a week, for 19 weeks. At week 20, animals were killed and skin tumors were analyzed histopathologically. The incidences of skin tumors in DMBA-EMF, DMBA-Sham, DMBA-TPA and DMBA-Control groups were 0/48 (0%), 0/48 (0%), 29/30 (96.6%) and 1/30 (3.3%), respectively. Histopathologically, papilloma and squamous cell carcinoma (SCC) were observed in the DMBA-TPA group and only papilloma observed in the DMBA-Control group. The incidences of squamous cell papillomas and squamous cell carcinomas in DMBA-TPA and DMBA-Control groups were 29/30 (96.6%) and 1/30 (3.3%), respectively, numbers of tumors per mouse (tumor multiplicity) being 18.8 +/- 13.4 and 0.1 +/- 0.5. These data clearly demonstrated that near fields exposure to 1.5 GHz EMF, used for cellular phones, does not exert any enhancing effect on skin tumorigenesis initiated by DMBA.

Epidemiology of Health Effects of Radiofrequency Exposure

“…Experimental evidence from animal and laboratory studies at the cellular level confirms the lack of genotoxic effect of RFs (Krewski et al 2001; Moulder et al 1999). Similarly, an investigation in rodents did not find support for the suggestion that growth of tumors induced by other agents may be promoted by RFs from mobile phone signals (Imaida et al 2001; Mason et al 2001). …”

Toxicity bioassay in Sprague-Dawley rats exposed to 20 kHz triangular magnetic field for 90 days

“…The most perplexing questions are those concerned with the problems of whether such an exposure either triggers or promotes disease processes. A few well-controlled human studies failed to show a positive association between exposure to RF radiation and carcinogenesis [Imaida et al, 2001;Bartsch et al, 2002], in vivo studies of chronic exposure of animals to repeated high and low level RF irradiation indicate a positive relationship between exposure and carcinogenesis [Rapacholi, 1997;Moulder et al, 1999]. The majority of the studies of long-term exposure indicate a negative impact on overall health, and suggest the possibility that RF radiation may have epigenetic activity, particularly at high exposure levels [Brusick et al, 1998;Verschaeve and Maes, 1998;Moulder et al, 1999].…”

Chronic exposure to a 1.439 GHz electromagnetic field used for cellular phones does not promote N‐ethylnitrosourea induced central nervous system tumors in F344 rats

“…Previously we conducted similar tumor initiationpromotion experiments to clarify whether EMF had a tumor enhancement effect on rat liver or mouse skin carcinogenesis [Imaida et al, 1998[Imaida et al, , 2000[Imaida et al, , 2001 and concluded that continuous local exposure did not have a tumor promoting activity. Furthermore, recent work in our laboratory with Big Blue mice demonstrated that local exposure to 900 MHz EMF did not cause mutations in mouse brain [Takahashi et al, 2002].…”