The American Cancer Society has stated that it is myth that cell phones cause cancer. However, the extensive use of cell phones is a relatively recent phenomenon, and since cancers usually take at least 10-20 years to develop, it is much too soon to conclude whether cell phones cause cancer or not. Meanwhile, there are several studies suggesting reasons for concern, and others indicating no increase.

A review of 18 studies of cell phones and brain tumors, published in Occupational Environmental Medicine in 2007 by Hardell and his colleagues, concluded that studies of individuals using cell phones for more than 10 years "give a consistent pattern of an increased risk for acoustic neuroma and glioma" with the risk being highest for a tumor on the same side of the head that the phone is used. Gliomas are the most common cancerous brain tumor and acoustic neuroma are a benign tumor of the acoustic nerve. The studies were conducted in the United States, Sweden, Finland, the U.K., Germany, and Japan.

A few of these studies were from the Interphone Project, which is an international effort to investigate possible tumor risks associated with the use of mobile phones in 13 countries. The U.S. is not participating in that research. Interphone studies define regular cell phone use as at least one call per week for at least 6 months, and long-term use is defined as at least one call each week for at least 6 years.

One of the 18 studies that found no increase is by Schuz and colleagues at the Danish Cancer Society and International Epidemiology Institute; they reported no significant increases in brain tumors, acoustic neuroma, or other head cancers among cell phone users. Funded at least partially by industry, this study included more than 420,000 Danes who first started a cell phone subscription between 1982 and 1995, and were followed through 2002 to determine if they were diagnosed with acoustic neuroma, gliomas, or other head cancers. Although the study is described as cell phone users "followed for up to 21 years" the average subscription was started only 8.5 years before the study was completed, and only 3% had started using cell phones 15 or more years ago. The researchers did not report the average number of years of cell phone usage, which may be considerably shorter. Individuals with corporate accounts were excluded from the sample, which is a shortcoming because they were the early adopters and heaviest users. There was no increased likelihood of brain cancers for those who used cell phones for more than 10 years; however, it is unclear how often they used cell phones more than 10 years ago. Another shortcoming is that the researchers did not evaluate on which side of the head the phone was used, which was a key variable predicting tumors in other studies. Perhaps most important, cell phone usage in the 1980s and 1990s is not comparable to the extensive use that is common today.

There are no studies of adults who used cell phones extensively as children and adolescents. Now that many children use cell phones, such studies are needed to determine whether children might be more vulnerable to exposure than adults.

A review of the above studies and dozens of others was recently completed by Vini Khurana, an Australian neurosurgeon. He concluded that heavy cell phone use can result in a doubling to quadrupling of the risk of brain tumors in users. His research review is not funded by cell phone companies and is currently being reviewed for publication in a scientific journal. Although not yet published, his report is attracting the attention of many health care providers and consumers. Those who would like to take precautions can read Dr. Khurana’s report and recommendations of how to reduce the risks of cell phones at http://www.brain-surgery.us/mobilephone.html.

In summary, the published research evidence so far indicates that using cell phones for several years does not have a clear impact on brain tumors or cancers. However, a growing number of studies suggest that tumors may be more common on the side of the head that is used for phone calls, especially for individuals using cell phones for more than 10 years. Most published studies evaluated relatively infrequent cell phone usage, and that research is inadequate to draw conclusions regarding safety. The health impact of the frequent, long-term use of cell phones that is typical today could potentially be substantially worse. That is why independent research reviews and more long-term studies are needed. Such research should not be funded by the companies that sell cell phones.