It's scary to hear that cellphones - devices that most of us have with us all the time - have been linked to cancer by a government study.
But despite any headlines you may have seen, there's still not enough information or evidence for the average person to be concerned by these findings.
"I'm not going to stop using my mobile phone in the light of this," Kevin McConway, emeritus professor of applied statistics at The Open University, said in a statement to the Australian and UK Science Media Centre.
Here's why you shouldn't panic
The latest results that we have access to are very preliminary findings from a peer-reviewed study conducted by the US National Toxicology Program (NTP). That experiment looked at the effects of cell phone radiation on a number of rats, and we won't see the full findings until at least later on this year.
So far, the released NTP data show a very weak link between excessive cell phone radiation exposure and the risk of developing some cancers. Specifically, male rats that were exposed to full-body doses of radiation for nine hours a day - from before the time they were born until they were just over two years old - were slightly more likely to develop brain and heart cancers than rats not exposed to that radiation.
It's an interesting finding, and one that could explain a mechanism by which radiation like that from cell phones could potentially cause cancer. That potential causal mechanism was enough to convince some involved with the study to release that information to the website Microwave News, which wrote about the results before NTP released the data.
SMercury98 via Flickr
If these results were to directly apply to humans, that would be scary. And if cell phone use increased human cancer rates even two or three percent (approximately the increased risk seen in rats), that would be a vast increase in the number of cancer cases across the globe.
But that's not what the data released so far shows, and extensive studies of human cell phone use certainly don't show cancer rates increasing in that way.
So far it's a stretch to apply this study to humans
First and foremost, rats are not humans, and many of the ways we test things on animals mean we find results there that don't end up translating to humans.
But the differences between the rats that did develop tumors in the experiment and the rats that did not leave us with a lot of questions.
Groups of rats were exposed to radiation at three different levels. These radiation levels were much higher than the levels most people are exposed to. Also, the rats were exposed to this radiation from before they were born to the end of the study for a full nine hours a day - not exactly replicating real-world human cellphone usage.
"I understand from information in the report that the lowest radiation levels used were somewhere around the safety limits imposed on mobile phone manufacturers, for the radiation when one is actually using the phone," said McConway. "It's certainly not yet obvious how these high-dose results in rats might tell us anything about normal levels of human mobile phone use."
Male rats exposed to radiation were more likely to develop tumors, but exposed rats were also more likely to survive the two-year test period than rats who were not exposed.
This "is counter intuitive given that the increased tumour rates normally lead to reduced lifespan," Rodney Croft, Director of the Australian Centre for Electromagnetic Bioeffects Research, told the Science Media Centre.
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A cancer cell.
Strangely, while an increased cancer risk was found in male rats, there was no increased cancer risk for female rats. And strangely, none of the rats in the control groups developed these brain tumors, which is not normal - some cancers would be expected in the control groups, too.
"The NTP study will thus need to be fully evaluated once further details become available, and considered within the context of RF emissions science as a whole," said Croft. "At present though, and particularly given a range of uncertainties regarding its results, the NTP report does not provide reason to move from the current scientific consensus that mobile phone-like exposure does not impact health."
The study gives us interesting information and definitely contributes to the discussion of the potential health impacts of cellphones. But for now, these results aren't quite as "explosive" as they've been described.
Scientists have previously said there's a possible chance that cell phone use could cause cancer (like almost everything ever studied, pickled vegetables and coffee included), but that so far, we haven't seen increased cancer incidence in humans that we can directly say comes from cell phone use.
"There has been much previous research on this topic, some of which has found no evidence of any risk, and some of which has found limited evidence of a small risk with heavy phone use. I don't think that these NTP results have moved us on from that yet," said McConway.