PhotoA $25 million U.S. government study has found a link between cell phones and cancer. The National Toxicology Program's multiyear study found links to two types of brain and heart tumors in rats exposed to the radio frequencies commonly used by cell phones.

In the brain, gliomas affect the gluey tissue that holds the neurons in place. Schwannomas generally affect hearing-related nerves when they occur in the brain. In the heart, they affect neurons and are generally benign but malignant heart schwannomas were found among the rats in the study. 

While the number of tumors was small, scientists said any incidence was worrying, given the massive number of people who use cell phones regularly worldwide.

“Given the widespread global usage of mobile communications among users of all ages, even a very small increase in the incidence of disease resulting from exposure to [radio-frequency radiation] could have broad implications for public health,” an early version of the study said. 

The NTP's report said the types of tumors found in the rats "are of a type similar to tumors observed in some epidemiology studies of cell phone use." It said the findings "appear to support" the International Agency for Research on Cancer (IARC) conclusions regarding the possible carcinogenic effects of cell phone radiation.   

The NTP undertook the study at the direction of the U.S. Food and Drug Administration (FDA). The National Institutes of Health (NIH) helped to oversee it and earlier this week noted that there was "limited evidence of an increased risk for developing cancer from cell phone use."

While rats and humans are not identical, rats are commonly used in cancer studies because their reactions to various carcinogens are similar to humans. The report released today covers only findings affecting the brain and heart. Additional findings will be released later, the NTP said. 

A wake-up call

The test was constructed so that the radiation level the rats received was "not very different" from what humans are exposed to when they use cell phones, said Chris Portier, former associate director of the NTP, Mother Jones reported.

Portier said the findings should be a wake-up call for the scientific establishment. "I think this is a game changer," he said. "We seriously have to look at this issue again in considerable detail," according to the Mother Jones report.

"The NTP does the best animal bioassays in the word," Portier added, the Mother Jones article said. "Their reputation is stellar. So if they are telling us this was positive in this study, that's a concern."

The wireless industry in the U.S. has long proclaimed, without any definitive evidence, that cell phones are harmless. CTIA, the wireless industry's trade group, no longer lists cancer as a topic on its website's Policy & Initiatives page. 

About the study

Cell phones emit what is called non-ionizing radio-frequency radiation (RFR). Ionizing radiation is a well-accepted human carcinogen, but the wireless industry and others have argued that there is no evidence that non-ionizing radiation could induce tumors.

For the study, rats were housed in custom-designed reverberation chambers and exposed to cell phone 900 MHz RFR, using both GSM and CDMA modulation, the two types that are in general use worldwide.

Exposures began in utero and continued over a period of approximately 18 hours using a continuous cycle of 10 minutes on (exposed) and 10 minutes off (not exposed), for a total daily exposure time of approximately 9 hours a day for 7 days per week.

A control group was housed in identical containers and not exposed to the radiations.

Brain effects

A low incidence of malignant gliomas and glial cell hyperplasia was observed in all groups of male rats exposed to GSM-modulated RFR. In males exposed to CDMA-modulated RFR, a low incidence of malignant gliomas occurred. No malignant gliomas or glial cell hyperplasias were observed in specimens of the control group, the NTP report said. 

In females exposed to GSM-modulated RFR, a malignant glioma was observed in a single rat. Glial cell hyperplasia was also observed in a single rat. In females exposed to CDMA-modulated RFR, malignant gliomas were observed in two rats. Glial cell hyperplasia was observed in one female in each of the CDMA-modulation exposure groups. There was no glial cell hyperplasia or any of the seven malignant glioma observed in females of the control group. 

Heart effects

Cardiac schwannomas were observed in male rats in all exposed groups of both GSM- and CDMA-modulated RFR, while none were observed in the control groups. For both the GSM and CDMA modulations, there was a "significant positive trend" in the incidence of schwannomas of the heart, according to the NTP report.

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