With over 4 billion cell phones in use worldwide, this once-exclusive device has almost become as common a personal accessory as watches and belts. But unlike your typical neck tie and pocket protector, cell phones must emit radiation to transmit its signal. High-dose radiation can cause cancer through DNA damage and mutations, but what about the low-dose emissions from cell phones?

For the moment, most research studies (related article) and prominent health organizations (i.e., World Health Organization, American Cancer Society, National Institutes of Health) have not linked cell phone use with an increased risk of cancer. But given that the mass adoption of cell phones only occurred approximately 20 years ago, long-term studies are lacking.

Last week, the UK-based Mobile Telecommunications and Health Research Programme (MTHR) officially launched the Cohort Study on Mobile Communications (COSMOS). The study aims to evaluate for any association between cell phone use and detrimental health effects, such as headaches, sleep disorders, cancers, and neurologic diseases. A pilot study performed in 2009 did not demonstrate an increase in either brain or nervous system cancers within 10 years of cell phone exposure. The COSMOS study now plans to extend the same project into a much larger prospective cohort over several decades.

The COSMOS study will invite adult cell phone subscribers from several European countries, including the United Kingdom, Finland, Netherlands, Sweden, and Denmark. The UK arm of the study will invite 2.4 million subscribers in hopes of enrolling 90,000 to 100,000 participants. The international collaboration plans to involve about 250,000 European participants. These individuals will be monitored over several decades for the development of cancers or neurodegenerative diseases.

One advantage this prospective study (following participants over time) has over previous retrospective studies (looking back in time) is the reduction of recall error. In retrospective studies, people may not accurately remember the details of their cell phone use from several years earlier. Another advantage of this study is its long duration. Some cancers and neurologic diseases require many years to develop, and shorter-term studies may not capture early sub-detectable or yet undiagnosed diseases.

This study is a welcomed endeavor to more robustly investigate the relationship between cell phone use and cancer. The first set of results are expected to be reported 10 years from now. For those who cannot wait until then for reassurance, wired earphones permit one to distance the cell phone from the heads. Presumably, this results in a lower-to-trivial level of radiation reaching the head. What about using those fancy Bluetooth devices with blinking lights? That, my friend, is a separate can of worms in itself.