ID Number		17
Study Type		In Vivo
Model		900 MHz (GSM) exposure to rats and analysis of cancer in two models: a DMBA-induced mammary tumor bioassay and a long-term spontaneous tumor model
Details		Sprague Dawley (female) rats given a single i.g. dose of DMBA (50 mg/kg) at day 51 and exposed (non-restrained in plastic cages) to a 900 MHz (GSM) RF at whole body average SARs from 0.017 - 0.07 W/kg (depending upon animal size during the course of the study) from day 51 until day 400. Weekly mammary tumor palpatation beginning 7 weeks after DMBA administration continued for 1 year. The overall data from three separate and replicate studies indicated no effect of exposure on either mammary tumor incidence for malignant (OR 1.08, CI 0.91-1.29) or benign (OR 0.96, CI 0.85-1.07) tumors or for mammary tumor latency. Authors' Abstract: Bartsch et al. 2012 (IEEE #5210): conditions displayed seasonal rhythms but subsequently were not always able to confirm this. Since there was no ndication under which conditions such rhythms may be present, we performed four consecutive identical experiments with untreated female SpragueDawley rats within the same animal room during 19972006. Nocturnal urine samples (1923, 233, 37 h) were collected at monthly intervals over 494658 d with 12 animals each in experiments I and II (19971999, 19992000), 30 animals in experiment III (20022004), and 15 in experiment IV (20052006). 6-Sulfatoxymelatonin (aMT6s) was measured by ELISA. The excreted aMT6s at each time interval as well as total nocturnal aMT6s-excretion (197 h) was submitted to standard statistical analyses as well as to a spectral chronobiological analysis to determine the period lengths of the components involved which was followed by processing with the single cosinor method. Seasonal rhythm components (circannual period length: 360 ± 60 d) were detected in experiment III (20022004) for the overall nocturnal excretion as well as for two sub-intervals (233 and 37 h) and in one night interval of experiment II (233 h). Multiple components with mostly short period lengths of around 100 d and some long ones of 500650 d were found in the other experiments. Systematic MESOR and amplitude variations were observed during the experiments, being highest in experiment II (197 h, also 233 h and 37 h) and lowest in experiments I and IV. These results illustrate that seasonal melatonin rhythms are not a general phenomenon in female laboratory rats indicating an involvement of unknown environmental cues. As an extension of our earlier hypothesis regarding a seasonal Zeitgeber function of the horizontal intensity H of the geomagnetic field showing circannual variations, we assume further modulation by the 11-yrs sunspot cycle which leads to geomagnetic disturbances and could facilitate seasonal aMT6s rhythmicity during specific years.
Findings		Effects
Status		Completed With Publication
Principal Investigator		University of Tubingen, FRG
Funding Agency		Deutsche Telekom, Germany
Country		GERMANY
References		Bartsch, H et al. Radiat. Res., (2002) 157:183-190 Bartsch , H et al. Neuro Endocrinol Lett., (2010) 31:457-473 Bartsch, H et al. Chronobiology International., (2012) 29:1048-1061
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