By Penny Stern, MD

NEW YORK, May 08 (Reuters Health) - Concerns have been raised about whether cell phone use can be linked to the development of brain tumors. Now, a study from Swedish researchers provides evidence backing the claim.

Dr. Lennart Hardell, of the department of oncology, at Orebro Medical Center together with colleagues there and at the Karolinska Institute in Stockholm, Sweden, describe their findings in the May 4th edition of Medscape General Medicine, an online peer-reviewed medical journal. Their results are based on questionnaire and interview data obtained from 209 persons with brain tumors and 425 healthy "control" subjects.

Hardell explained to Reuters Health that in a 2-year study, the team found "an increased risk in anatomical areas of the brain...exposed (to microwaves) during a mobile phone call." This risk holds even when statistical adjustments are made for other risk factors including ionizing radiation and laboratory exposures, Hardell said.

The researcher pointed out, however, that most of the people in the study "used the older analog system, which gives two to three times higher exposure than the digital system, which is now mostly used--at least in Europe."

He stressed that "larger studies are necessary to make firm conclusions." In fact, he and his team "have a much larger brain tumor study ongoing with about 1,500 incident patients and 1,500 controls. The results are expected within one year." Nevertheless, "our findings indicate that prudent avoidance of exposure" is warranted, he added.

In light of their current findings, Hardell offers several suggestions about cell phone usage. "Use...an earpiece to reduce exposure to the brain (and), in a car, use (an) external fixed antenna," he said. "Otherwise, your exposure to microwaves might even be higher than using the phone outside the car." In addition, he advised that extended conversations be conducted on a regular telephone.

Insofar as children are concerned, Hardell commented that since "the developing brain might be more sensitive to microwaves," children's exposure should be limited.

One useful tip he suggests is to find out the specific absorption rate (SAR) value of various cell phone types. "The SAR may differ (by as much as a factor of) 20...between different brands," Hardell cautioned.

According to the researcher, he and his colleagues were somewhat surprised by their results since microwaves have not been shown to be toxic to cells in the way that ionizing radiation has. Ionizing radiation includes x-rays and ultraviolet rays, both of which can cause harmful effects to living organisms.

The journal Medscape General Medicine is available at http://www.medscape.com/journal/MedGenMed.

SOURCE: Medscape General Medicine, May 4, 2000.

http://www.doctorbob.com/ - 05/10/2000