Report of final results regarding brain and heart tumors in Sprague-Dawley rats exposed from prenatal life until natural death to mobile phone radiofrequency field representative of a 1.8 GHz GSM base station environmental emission.

In 2005, the Ramazzini Institute performed a lifespan study on Sprague-Dawley rats to evaluate the carcinogenic effects of radio-frequency radiation. This study has now been concluded and the findings suggest that the classification of radiofrequency radiation as possibly carcinogenic to humans (Group 2B) should be reevaluated. Already in the early 2000s, published studies showed that those who use cell phones have a significantly higher risk of developing brain tumors and schwannomas (benign tumors of the peripheral nervous system). Modern case-control studies also confirm this increased risk. Experimental studies, however, were for the most part insufficient because of too short exposure durations, too few study animals or incorrect exposure conditions. The study by the Ramazzini Institute, however, used a total of 2448 animals.

A total of 2448 study animals were analyzed. The animals were exposed for 19 hours per day from day 12 of gestation until their natural death. A 1.8 GHz GSM antenna (2G) served as the radio-frequency radiation source. The study animals were divided into 4 groups. Group I was the control group and the animals were not exposed. Group II was exposed, resulting in a SAR value of 0.001 W/kg. Group III and Group IV were also exposed, resulting in a SAR value of 0.03 W/Kg and 0.1 W/Kg. To rule out any external exposure, the animals were housed in shielded rooms. The clinical status of the study animals was unremarkable for the entire duration of the experiment. There were also no differences among the groups with regard to such biological parameters as water and food intake as well as survival index throughout the entire experiment. The scientists used histopathological methods to assess the brains and hearts of the study animals.

The research group found that the male rats of Group IV had developed statistically significantly more heart schwannomas than those in the control group (0% vs. 1.4%). In contrast to humans, schwannomas in rats are classified as malignant tumors. Furthermore, the male animals of this group also showed an increased incidence of hyperplasia (excessive increase in the number of cells produced) in the Schwann cells of the heart; this increase, however, was not statistically significant (0.7% vs. 2.4%). This increased incidence of hyperplasia in the Schwann cells of the heart was also observed in the female animals of Group IV. In the latter group, statistical significance was not reached either (0.5% vs. 1.0%). Likewise, the analysis of the brains of the rats did not produce any statistically significant data. In female animals, however, a trend could be observed that was dependent on the exposure level: 0.5% of Group I, 0.7% of Group II, 1.0% of Group III and 1.5% of Group IV developed malignant gliomas (tumors of glial cells in the central nervous system). It is remarkable that the US National Toxicology Program (NTP) carried out a study that is similar to the one by the Ramazzini Institute (Wyde et al. 2018). In the NTP study, rats were exposed to radio-frequency radiation as follows: 18 h/day, 10 min on / 10 min off, 7 day/week, 104 weeks. The animals were also divided into four groups with SAR values ranging from 0, 1.5, 3 to 6 W/kg. In contrast to the study by the Ramazzini Institute, the animals in the NTP study were not exposed for quite as long (18 h instead of 19 h), not continuously (10 min on / 10 min off) and for a shorter duration (104 weeks instead of whole lifespan), but at much higher exposure levels. The observations of both research groups are in agreement with regard to the histopathological analysis of the hearts and brains.

Due to the authors, the Ramazzini study is significant for three reasons:

> Even the small increase in tumor incidence observed in the study can have a great impact on public health.

> The two independent studies by the Ramazzini Institute and the US National Toxicology Program show data that is in agreement.

> The observed tumors originate from the same types of cells that have been found in the mentioned epidemiological case studies of cell phone users. Based on these experimental studies, the scientists demand that the cancer classification of radio-frequency electromagnetic fields by the International Agency for Research on Cancer (IARC) shall be reevaluated. (IW)