Motorola 280 - Manual (Page 186)

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First, it is uncertain how to apply the results obtained in rats and
mice to humans. Second, many of the studies that showed
increased tumor development used animals that had already
been treated with cancer-causing chemicals, and other studies
exposed the animals to the RF virtually continuously—up to 22
hours per day.
For the past five years in the United States, the mobile phone
industry has supported research into the safety of mobile
phones. This research has resulted in two findings in particular
that merit additional study:
1 In a hospital-based, case-control study, researchers looked
for an association between mobile phone use and either
glioma (a type of brain cancer) or acoustic neuroma (a
benign tumor of the nerve sheath). No statistically
significant association was found between mobile phone
use and acoustic neuroma. There was also no association
between mobile phone use and gliomas when all types of
types of gliomas were considered together. It should be
noted that the average length of mobile phone exposure in
this study was less than three years.
When 20 types of glioma were considered separately,
however, an association was found between mobile phone
use and one rare type of glioma, neuroepithelliomatous
tumors. It is possible with multiple comparisons of the same
sample that this association occurred by chance. Moreover,
the risk did not increase with how often the mobile phone
was used, or the length of the calls. In fact, the risk actually
decreased with cumulative hours of mobile phone use.
Most cancer causing agents increase risk with increased
exposure. An ongoing study of brain cancers by the