健康提示：请跟你的手机保持距离

WARNING: Holding a cellphone against your ear or storing it in your pocket may be hazardous to your health。

　　This paraphrases a warning that cellphone manufacturers include in the small print that is often tossed aside when a new phone is purchased. Apple, for example, doesn't want iPhones to come closer to you than 1.5 centimeters; Research In Motion, BlackBerry's manufacturer, recommends 2.5 centimeters。

　　If health issues arise from cellphone use, the implications are huge. Voice calls - Americans chat on cellphones 2.26 trillion minutes annually - generate $109 billion for the wireless carriers。

　　Devra Davis, an epidemiologist who has worked for the University of Pittsburgh, has published a book about cellphone radiation, "Disconnect." The book surveys scientific research and concludes the question is not settled。

　　Brain cancer is a concern that Ms. Davis examines. Over all, there has not been an increase in its incidence since cellphones arrived. But the average masks an increase in brain cancer in the 20-to-29 age group and a drop for the older population。

　　"Most cancers have multiple causes," she says, but she points to laboratory research that suggests low-energy radiation could damage cells that could possibly lead to cancer。

　　Children are more vulnerable to radiation than adults, Ms. Davis and other scientists point out. Radiation that penetrates only five centimeters into the brain of an adult will reach much deeper into the brains of children because their skulls are thinner and their brains contain more absorptive fluid. No studies have yet been completed on cellphone radiation and children, she says。

　　Henry Lai, a research professor in the bioengineering department at the University of Washington, began laboratory radiation studies in 1980 and found that rats exposed to radiofrequency radiation had damaged DNA in their brains。

　　Ms. Davis recommends using wired headsets or the phone's speaker. Children should text rather than call, she said, and pregnant women should keep phones away from the abdomen。

　　警告：将手机贴在耳边或者塞在口袋里可能有害健康。

　　在消费者购置新机后，常对手机厂商印在不起眼位置的小字警告不以为然。例如，苹果公司提醒称iPhone手机距离人体至少要有1.5厘米，黑莓手机生产商RIM公司建议最小距离为2.5厘米。

　　如果手机使用可导致健康问题，后果将很严重。美国每年手机通话的时长共计2.26万亿分钟，这些语音通话为无线运营商带来了1090亿美元的收入。

　　匹兹堡大学的流行病学专家德芙拉?戴维斯出版了一本有关手机辐射的书《关机》。这本书对有关科学研究进行了调查，其结论是：这个问题还没有定论。

　　脑癌是戴维斯女士研究的辐射后果之一。总体而言，自手机出现以来，脑癌发病率并未上升。但这一平均率掩盖了如下事实：脑癌在20至29岁年龄群体中的发病率增加，而在老年人群中的发病率下降。

　　她说：“大多数癌症具有多种病因。”但她指出，实验室研究表明，低能辐射会损害人体细胞，而这又有可能导致癌症。

　　戴维斯女士及其他一些科学家指出，儿童比成人更容易受到辐射的影响。由于儿童的颅骨更薄，而且大脑中含有更多易吸收辐射的液态物质，因此渗入成人大脑仅5厘米的手机辐射能够渗入到儿童大脑内更深的区域。她表示，手机辐射对儿童影响方面的研究目前还不完善。

　　华盛顿大学生物工程系研究教授赖亨利自1980年开始进行辐射实验研究。他发现，受到射频辐射的实验鼠脑组织DNA会受损。

　　戴维斯女士建议大家使用有线耳机或手机扬声器，儿童应尽量收发短信而不是打电话，而怀孕妇女应将手机远离腹部。