As wireless communication companies seek permission to erect more and more cellphone towers on West Seattle apartment buildings, it's difficult to figure out how many antennas there are because the city doesn't keep a running total and companies won't reveal how many they have.

The Seattle Department of Planning and Development approves individual applications to install so-called "minor communication utilities" with transmitting and receiving towers for cellphone users. But the department doesn't keep track of how many cell towers there are in West Seattle or the rest of the city, said Alan Justad, department spokesman.

Most wireless companies won't divulge how many antennas they have in their respective systems. Those are considered trade secrets.

"That is information Sprint doesn't typically give out," said Debra Havins, a company spokeswoman. "It's proprietary information."

Each cellphone company uses different technology so the radiofrequency signals of some systems require more towers than other systems, Havins said.

"It's possible for people to misinterpret," she said. "Does this company have too many? Does that company have too few?"

AT&T Wireless, which recently acquired Cingular Wireless, would not reveal the number of cell towers it operates in West Seattle either, said Lauren Garner, spokeswoman.

Nor would Verizon Wireless.

T-Mobile spokesman Steve Caplan would say only that his company has "hundreds" of towers in the Greater Seattle area. T-Mobile applied to the city to install a new wireless communication facility atop a six-floor apartment building on Alki Avenue as well as on a five-story building on Lincoln Park Way.

The uptick in applications for new cell towers is partly the result of the huge growth in the use of cell phones and the widening array of new things the devices can do, Caplan said.

Companies started out putting up cell towers near freeways and other commuter routes, Caplan said. But as people began using cell phones for personal use at home as well as on the job, companies had to find more antenna sites closer to residential neighborhoods, he said.

Additionally, people now use cell phones for much more than verbal conversations. They send text messages, check e-mail, and watch TV and movies. That requires even more wireless facilities, Caplan said.

While the city of Seattle has jurisdiction over where cellphone towers can be situated, it is the Federal Communications Commission that regulates how much radiofrequency radiation the equipment emits. There is little scientific evidence that wireless communication transmitters and receivers cause human health problems because the technology operates on low frequencies. High-speed broadband service brings about as many radiofrequencies as a baby monitor, said Lauren Garner, spokeswoman for AT&T Wireless.

Meanwhile, the Seattle City Council unanimously passed an ordinance in 2004 establishing priorities for picking cell tower sites. The effort was supported by Mayor Greg Nickels.

A Department of Planning and Development "director's rule" subsequently stated industrial sites are to be preferred for cellphone antenna installations. Next best are sites in downtown Seattle. Third choice is commercial zones.

Following those preferred places are neighborhood commercial zones, then multifamily zones on arterial streets and, lastly, multifamily zones on nonarterial streets.

The director's rule also says cellphone towers should be placed in the least intrusive location.

In addition, the director of the Department of Planning and Development can choose a third party radiofrequency engineer to verify technical information supplied by a cellphone company in its application. Further, the rule requires a third-party technical review for all cellphone antenna bases planned in single-family neighborhoods

Tim St. Clair can be reached at timstc@robinsonnews.com or 932-0300.