SAN FRANCISCO

The great cosmic joke would be to find out definitively that the advances we thought were blessings ”” from the hormones women pump into their bodies all their lives to the fancy phones people wait in line for all night ”” are really time bombs.

Just as parents now tell their kids that, believe it or not, there was a time when nobody knew that cigarettes and tanning were bad for you, those kids may grow up to tell their kids that, believe it or not, there was a time when nobody knew how dangerous it was to hold your phone right next to your head and chat away for hours.

We don’t yet really know the physical and psychological impact of being slaves to technology. We just know that technology is a narcotic. We’re living in the cloud, in a force field, so afraid of being disconnected and plunged into a world of silence and stillness that even if scientists told us our computers would make our arms fall off, we’d probably keep typing.

San Francisco just became the first city in the country to pass legislation making cellphone retailers display radiation levels. The city’s Board of Supervisors voted 10 to 1 in favor. The one against, the Democrat Sean Elsbernd, said afterward: “It’s a slippery slope. I can go on Google right now and find you a study that says there’s a problem with the Starbucks you’re drinking.”

Different phone models emit anywhere from 0.2 watts per kilogram of body tissue to 1.6 watts, the legal limit. The amount of radio frequency energy seeping into the body and brain is measured by a unit called the Specific Absorption Rate (SAR).

“You see all these kids literally glued to their phones,” Gavin Newsom, the mayor of San Francisco, told me. “And candidly, my wife was pregnant and on her cellphone nonstop. So I dusted off some studies and started doing research.

“That’s when I discovered that companies who make cellphones are already required to disclose that information to the federal government, and that it exists but somewhere on someone’s Web page on the 88th page.” Why not underscore it, he thought, by alerting consumers at the store, putting the SAR level in the same font as the phone price?

His alarmed advisers, accustomed to seeing the sleek Newsom diving into bold stands without calculating the potential blowback ”” as with gay marriage ”” told him to focus on jobs and the economy.

“They said: ”˜There you go again. They’re going to mock you. It’s going to be another sideshow,’ ” he recalled. But stroking his baby daughter’s soft head and reading new studies on the vulnerability of children’s thinner skulls to radiation, he persevered.

One Swedish study that followed young people who began using cells as teenagers for 10 years calculated a 400 percent increase in brain tumors. But as Nathaniel Rich recently pointed out in Harper’s, studies about cellphones’ carcinogenic potential all contradict one another, including those involving children.

When Newsom proposed the bill, telecommunications lobbyists went to the mattresses, as did hoteliers, who feared losing convention business.

He said that lobbyists from Washington made it clear that they would invoke “the nuclear option” and come down “like a ton of bricks.”

“This is tobacco money, oil money,” he said. “But these guys from D.C. do not know me because that has exactly the opposite effect. Shame on them, to threaten the city. It’s about as shortsighted as one could get in terms of a brand.”

Months before the bill passed, he read me part of a letter that Marriott sent him: “CTIA ”” The Wireless Association, which is scheduled to hold a major convention here in October 2010, has already contacted us about canceling their event if the legislation moves forward. They also have told us that they are in contact with Apple, Cisco, Oracle and others who are heavily involved in the industry, as you know, about not holding future events in your city for the same reason.”

Sure enough, when the bill passed Tuesday, CTIA issued a petulant statement that after 2010, it would relocate its annual three-day fall exhibition, with 68,000 exhibitors and attendees and “$80 million” in business, away from San Francisco.

“Since our bill is relatively benign,” Newsom said, “it begs the question, why did they work so hard and spend so much money to kill it? I’ve become more fearful, not less, because of their reaction. It’s like BP. Shouldn’t they be doing whatever it takes to protect their global shareholders?”

So now we have Exhibit No. 1,085 illustrating the brazenness of Big Business.

They should be sending Mayor Newsom a bottle of good California wine for caring about whether kids’ brains get fried, not leaving him worried about whether they’ll avenge themselves in his campaign for lieutenant governor.

He’s resigned to that possibility, just as he is to his own addiction. “I love my iPhone,” he said cheerfully.