What should one look for when evaluating claims on the possibility that cell phones cause brain tumors and other health claims?
I just read an article claiming that cell phone usage increases the risk of brain tumors. I have also read contradictory research reports claiming no connection. Contradictory claims for health research are common; so how does one evaluate health claims?
News articles often leave out crucial details. Look for in-depth articles that give necessary details, or better yet, the original article. Articles in peer reviewed medical/scientific journals are best.
The human body is extremely complex making epidemiological studies complex. Small effects are difficult to isolate causing many contradictory studies. For claims about health effects of cell phones, or anything else, don't rely on a single study. Look at many studies for overall trends.
When evaluating studies consider the following points:
- How large is the study sample? Larger samples are more likely to be accurate.
- Is there a control sample? Controlled double blind studies are the gold standard for medical research.
- Are variables properly isolated? A good study isolates or corrects for other variables so that only the tested variable changes.
- To claim an effect, there should be a correlation, the stronger the better. However that is not enough. Correlation does not prove causation. So to claim something causes a health effect, good or bad, there should also be a plausible mechanism. In the case of cell phones, they send their signals via microwaves. Microwaves are very low energy electromagnetic waves, but there is a very small possibility repeated exposure could cause cellular damage.
- How long did the study last? Very small effects, such as from cell phones, may take decades to cause problems.
We won't really be able to reliably evaluate the long term effects of constant cell phone exposure on brain tumors until cell phones have been around for several decades.
