“The industry had come out and said that there were thousands of studies that proved that wireless phones are safe, and the fact was that there were no studies that were directly relevant,” says Dr. George Carlo.

For the past six years, Carlo ran the cell phone industry’s $25 million research program, which has studied the effects of microwave radiation from cell phones.

“We’ve moved into an area where we now have some direct evidence of possible harm from cellular phones,” Carlo says in an interview with ABCNEWS’ 20/20.

Although Carlo does not say that cell phones are unsafe, he does say that more research is needed.

The $200-billion-a-year cell phone industry maintains the devices are safe.

“There is a preponderance of evidence that there is not a linkage between the use of wireless phones and health effects,” says Thomas Wheeler, president of the Cellular Telecommunications Industry Association, the industry’s trade group.

The industry has announced that it supports and will sponsor follow-up research.

Electromagnetic Waves Sent Into Brain
What many of the country’s 80 million cell phone users may not know is that cell phones send electromagnetic waves into users’ brains. In fact, every cell phone model sold in the United States has a specific measurement of how much microwave energy from the phone can penetrate the brain.

Depending on how close the cell phone antenna is to the head, as much as 60 percent of the microwave radiation is absorbed by and actually penetrates the area around the head, some reaching an inch to an inch-and-a-half into the brain.

“This is the first generation that has put relatively high-powered transmitters against the head, day after day,” says Dr. Ross Adey, who has worked for industry and government for decades studying microwave radiation, and is one of the most respected scientists in the field.

Position Matters
The cell phone industry says every phone it sells is safe and meets government radiation safety limits. But tests conducted by 20/20 and being made public on tonight’s program have found that some of the country’s most popular cell phones can — depending on how they’re held — exceed the radiation limit.

20/20 reports that government testing guidelines are so vague that a phone can pass the Federal Communications Commission’s requirements when tested in one position and exceed those maximum levels when held in another position.

The cell phone industry says every phone sold in the United States meets the federal safety standard, and that there is a huge margin of safety built into the standard.

“There isn’t data to show that what is happening has a health effect,” Wheeler says, adding that there is no need for Americans to cut back on their cell phone use.

Along with the test results, the 20/20 story shows how users can significantly reduce their exposure to microwave radiation from cell phones.

Richard Allyn and Brenda Breslauer contributed to this report.