[See: A Guide to Cancer Prevention.]

Meanwhile, the U.S. Federal Communications Commission is in the midst of reviewing its safety guidelines for radiofrequency exposure. The current guidelines, based on recommendations from federal health and safety groups like the Environmental Protection Agency and Food and Drug Administration, were adopted in 1996.

"The U.S. has among the most conservative standards in the world," says Neil Grace, FCC senior communication adviser. "As part of our routine review of these standards, which we began last year, we will solicit input from multiple stakeholder experts, including federal health agencies and others, to guide our assessment."

Lori Wirth, medical director of the Center for Head and Neck Cancers at Massachusetts General Hospital, calls Hamzany's data "very interesting and intriguing," but adds that it merits a "healthy amount of caution." "We don't know if there is a direct link between markers of oxidative stress in saliva and the risk of cancer," she says. "We do know that oxidative stress can lead to DNA damage, free radical damage of DNA, and that is one potential mechanism of carcinogenesis."

But the more immediate threat from cellphones, she argues, has nothing to do with cancer, and points instead to the more mundane hazards of distracted driving.

lěng xiào huà jīng xuǎn sān zé ，jué duì jīng diǎn hǎo xiào ！

1、zǎo shàng lǎo gōng lài chuáng ，yòng bèi zi bǎ zì jǐ guǒ le hǎo jǐ céng 。wǒ yī qì jiù yòng pí dài lán yāo gěi tā bǎng bèi zi lǐ ，rán hòu qù shàng bān le 。xià wǔ huí lái ，kàn jiàn lǎo gōng bǎo chí zhe zǎo shàng de zào xíng ，yǎn shén yōu yuàn de kàn zhe wǒ 。tā shuō ：“è le yì tiān bú shì guān jiàn ，méi kòng tiáo rè sǐ liǎo bú shì guān jiàn ，míng tiān zěn me qù dān wèi jiě shì méi shàng bān ér qiě bù jiē diàn huà yě bú shì guān jiàn ，guān jiàn shì ： niào méi yǒu biē zhù …”