A study conducted by the National Toxicology Program (NTP) found carcinogenic activity in male rats exposed to a radiofrequency radiation (RFR) rate much higher than the current safety standard set for cell phone emissions. The study, nominated by the Food and Drug Administration (FDA), has been called the most comprehensive assessment of RFR exposure in rodents to date.

Researchers at the NTP exposed rats and mice to levels of RFR frequency that was equal to and higher than the highest level permitted for local tissue exposure in cell phone emissions for up to two years. The studies used 2G and 3G frequencies and modulations which are still used in voice calls and texting in the U.S. Rats were exposed to 1.5 to 6 watts per kilogram (W/kg) and mice to 2.5 to 10 W/kg — the lowest level is equivalent to the highest permitted level for today’s exposures in cell phone emissions.

The researchers found that in male rats the incidence of malignant schwannoma in the heart increased with higher levels of RFR. Unusual patterns of cardiomyopathy were also noted in exposed  male and female rats, however no health problems were seen in any of the exposed mice.

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Acknowledging how the levels of exposure in the study were much greater than those experienced by people, John Bucher, PhD, and senior scientist at NTP said, “These findings should not be directly extrapolated to human cell phone usage.” However he went on to remark that, “The tumors we saw in these studies are similar to tumors previously reported in some studies of frequent cell phone users.”

The Federal Communications Commission (FCC) sets the standard for radiofrequency cell phone exposure limits, however they base their standards on scientific research from the FDA and other health agencies.

The FDA explained in a statement how, “The current safety limits are set to include a 50-fold safety margin from observed effects of radiofrequency energy exposure.” They went on to say that the results still require ‘careful discussion’, and that they would be participating in a peer review of the study, due to take place during March 26-28.

For more information visit ntp.niehs.nih.gov.