An over 10-year-long study about the link between mobile phone radiation and cancer has shown a ‘clear evidence’ of high levels of exposure and heart cancers, but in male rats.

A long-running study by the National Toxicology Program (NTP) about the effects of radio wave radiation emitted by mobile phones finally came to an end revealing that there is a possible risk of cancer in male rats, but only under specific circumstances.

The study included exposing rats and mice to high levels of radio frequency radiation (RFR) for nine hours a day for two years. Some evidence of links to brain and adrenal gland tumors in male rats were found, but in female rodents and male mice, signs of cancer weren’t clear.

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The radiation exposure was well above the levels most humans would experience and cannot be compared to humans, but as per the researchers, the findings show link between RFR and tumors, at least for rats, reported Independent.

“The exposures used in the studies cannot be compared directly to the exposure that humans experience when using a cell phone. In our studies, rats and mice received RFR across their whole bodies. By contrast, people are mostly exposed in specific local tissues close to where they hold the phone.

“In addition, the exposure levels and durations in our studies were greater than what people experience. We believe that the link between RFR and tumors in male rats is real, and the external experts agreed,” said NTP scientist John Bucher.

The team discovered that 5%-7% of male rats developed malignant schwannomas (a type of nerve tumor) in their hearts, while 2%- 3% of male rats developed malignant gliomas (a deadly brain cancer). However, none of the rodents in the control groups developed these conditions, wrote Futurism.

Also, in female rats and both sets of mice, evidence of cancer formation was ‘equivocal’ meaning there were measurable increases in molecules at times linked to cancer, but no actual evidence was found.

However, the $30 million study was focused on radiation frequencies used by 2G and 3G mobile phones, as compared to the phones that are now moving on to 4G, LTE and 5G technologies.

“5G is an emerging technology that hasn’t really been defined yet. From what we currently understand, it likely differs dramatically from what we studied,” said lead toxicologist Michael Wyde.