Thursday, July 31, 2008

Dial 'C' for Cancer

I'm not a cell phone user. Even my grandfather has made the leap, while I remain in the technological dark ages with a phone attached to the wall with a wire! But despite being completely unreachable the second I walk out the door, there may be a bright side. Last week, the director of the University of Pittsburgh Cancer Institute issued a warning about cell phone use and a potential link to cancer:
The head of a prominent cancer research institute issued an unprecedented warning to his faculty and staff Wednesday: Limit cell phone use because of the possible risk of cancer.
The warning from Dr. Ronald B. Herberman, director of the University of Pittsburgh Cancer Institute, is contrary to numerous studies that don't find a link between cancer and cell phone use, and a public lack of worry by the U.S. Food and Drug Administration.
Now this is something many of us have heard before - cell phones cause cancer - but how true is it? Is this warning warranted, or is Dr. Herberman yelling fire in the proverbial theatre? Since the data this is being based on is unpublished, it's impossible for me to comment on. However, studies on cell phones and cancer have been done, so we can look at the data we have so far.

Several years ago, the US Food and Drug Administration consumer magazine had a piece explaining some of the difficulties in getting an answer to the phone-cancer question. The article included a very brief summary of studies that had been done (as well as some commentary by cancer researchers). The conclusion there was that there is very little to no risk of brain cancer from cell phone use. However, the intervening 8 years has been ample time for further studies to be done. A quick pubmed search shows numerous animal studies that show no increase in cell death or proliferation in mice exposed to non-ionizing radiation of the same frequency used by mobile phones. Many of the human studies (retrospective studies, for example here and here) are also negative, but they aren't exclusively so. While meta-analysis is not ideal for answering this type of question (see here for a brief discussion, particularly Bayman's commentary there), so far this year at least two meta-analyses have been done on the issue. This study found no overall increase of brain tumors (though they note in a subset of the cases included in the analysis that there is a potential elevated risk with long term cell-phone use). Similarly, this analysis is more assertive in its conclusions, claiming "a consistent pattern of an association between mobile phone use and ipsilateral glioma and acoustic neuroma using > or =10-years latency period" (while their data show that shorter term use is not associated with increased brain cancers).

So what's the answer? Is there a risk to cell-phone use? The literature seems to indicated that in the short term, no, probably not. Long term (>10 years) usage starts to tilt things towards the positive, although not in a huge way (the studies mentioned above indicate that the increased risk is relatively small). As is usually the case with these situations, the answer will probably bounce back and forth for awhile until a definitive study is done to put the question to rest

This brings us back to the renewed warnings issued last week. Given that the potential risks are small (but not negligible) and associated only with long term exposure, the question becomes what was the proper way to deal with the unpublished data from the University of Pittsburgh Cancer Institute? Again, it's difficult to say without seeing the data in question, but given the information we have so far it's hard to imagine a definitive, home-run conclusion (Herberman, who issued the warning, says as much in the news article). Should he have waited for peer review before sounding the alarm (would an extra few months before releasing it make a difference when talking about a 10 year latency)? Is it better to err on the side of caution? After all, he's not calling for an end to cellphone use, but rather certain precautions, particularly with children. Dr. Herberman defends himself thusly:
Herberman is basing his alarm on early unpublished data. He says it takes too long to get answers from science and he believes people should take action now - especially when it comes to children.
"Really at the heart of my concern is that we shouldn't wait for a definitive study to come out, but err on the side of being safe rather than sorry later," Herberman said.
Without seeing the unreleased data, is it enough to change your cellphone habits? For the University of Pittsburgh statement and the recommended precautions, go here.


3 comments:

Anonymous Coward said...

The bayblab team has preliminary evidence that there may be harmful gases in the atmosphere such as evaporated ethanol. While that paper is in peer review, refrain your children from breathing...

Anonymous said...

This topic has been visited before on the bayblab.

kamel said...

So it has. So maybe we can shift the discussion to the second part of the post and how to handle unpublished findings, particularly with a potential public health issue.