Are cell phones safe? Research hasn't proved any hazards, but there may be cause for concern.

Ten years ago, David Reynard said on Larry King's CNN talk show that he blamed his wife's brain tumor on her cell-phone use. After her death, he sued a cell-phone carrier and a maker, charging that the phones had health risks.

A federal judge eventually dismissed the lawsuit for lack of scientific evidence. But questions remain that new research has yet to resolve. More than 70 research papers on the potentially adverse effects of cell-phone use have been published in the past decade. Some have raised concerns about cancer, neurological disorders, sleep problems, or headaches; others have shown no association or were inconclusive.

The major unanswered question: Can exposure to low levels of electromagnetic energy that the body absorbs from a cell phone be harmful? (A phone emits the most radiation when you're on a call, but it also emits small amounts periodically whenever it's turned on.)

The federal government sets upper exposure limits to electromagnetic energy from cell phones known as the specific absorption rate, or SAR. However, the SAR limit does not address other effects, such as those from very low levels of radiation on cells and tissues.

CONFLICTING FINDINGS

The government's stance on cellular safety comes in this carefully worded but equivocal statement from the Food and Drug Administration (FDA) and Federal Communications Commission (FCC): "The available scientific evidence does not show that any health problems are associated with using wireless phones. There is no proof, however, that wireless phones are absolutely safe."

To help clarify matters, the FDA made a research agreement with the Cellular Telecommunications & Internet Association (CTIA) in June 2000. The FDA provides scientific oversight for CTIA-funded research. Three studies, involving lab and animal tests, are expected to be completed later this year.