The Internet antenna proposed for installation near a Walnut Creek elementary school takes wireless communication to a new level.

The 37-foot tower uses a technology called WiMax, and it spreads its radio waves far wider than standard Wi-Fi radio waves.

"Wi-Fi is very focused on a specific small area, a coffee shop or a library," said Debra Havins, spokeswoman for Clearwire, a Kirkland, Wash., company that sells the antennas. "WiMax is much broader, its coverage is measured in miles rather than a few feet."

The prospect of such a powerful antenna rising just a few hundred feet from Walnut Heights Elementary School playground had parents and activists crying foul at a school meeting Wednesday, as they expressed alarm over the health hazards of the nonstop radio waves the tower would emit if it were installed.

"A lot of people are still saying, 'Oh, the science is inconclusive,' " said Ellie Marks, an Orinda real estate agent who has become an outspoken advocate for greater regulation of equipment emitting radio waves, or non-ionizing radiation. "However, if there's a risk, I don't want my kid to be the guinea pig."

Havins, however, pointed to decades of study on the issue.

"At this point there is nothing conclusive," she said, "and there's no reason to believe they constitute a potential health hazard to nearby residents or students."

The antennas also emit electromagnetic radiation that falls within Federal Communications Commission guidelines addressing human health hazards, she said.

A call to the FCC seeking information on the studies it uses to develop its guidelines wasn't returned Thursday.

But Martin Blank, a professor of biophysics at Columbia University in New York City with an expertise on the health effects of electromagnetic radiation, regards the federal regulations as inadequate.

"I think the parents are right to be concerned," Blank said. "The fact of the matter is that electromagnetic fields over a whole range of frequencies have very potent biological effects."

Blank cited numerous potential health effects of electromagnetic radiation, including Alzheimer's disease and leukemia, and studies backing them. He and other scientists wrote the BioInitiative Report detailing their concerns, which is available at www.bioinitiative.org.

Blank also said his research has shown that electromagnetic energy, including the radio waves used in wireless communication, activate a cellular stress response that indicates cellular damage. It's a protective mechanism that increases the levels of stress proteins that help repair damaged proteins.

"The biochemical changes are indicative of dangers," he said.

The American Cancer Society noted a 1999 study from the National Institutes of Health that said evidence for health harms from electromagnetic fields was "weak" but could not be totally discounted.

"The conflicting data concerning electromagnetic fields will undoubtedly continue to generate controversy," the organization said on its Web site. "Clearly, the question of whether or not electromagnetic fields can cause cancer needs to be answered."

Suzanne Bohan covers science. Contact her at 510-262-2789. Follow her on Twitter at www.twitter.com/SuzBohan.