TUESDAY, Oct. 13 （HealthDay News） -- The latest study focusing on a possible cell phone-brain tumor connection finds a weak potential link between the two.

    A review of existing research on the topic, published online Oct. 13 in the Journal of Clinical Oncology, discerned no overall link. But when the spotlight was turned on only the more methodologically rigorous studies, a potentially harmful association was found.

    Combined with similarly murky conclusions from earlier research, this leaves the world's four billion cell phone users with no clear indication of what risk, if any, they are taking when they converse on the go.

    "We cannot make any definitive conclusions about this," said one expert, Dr. Deepa Subramaniam, director of the Brain Tumor Center at Georgetown Lombardi Comprehensive Cancer Center in Washington, D.C. "But this study, in addition to all the previous studies, continues to leave lingering doubt as to the potential for increased risk. So, one more time, after all these years, we don't have a clear-cut answer."

    "What makes me worry," she stated, "is that the higher quality studies [seen here] did indeed show an association."

    Joel Moskowitz, the study's senior author, said that "clearly there is risk." He's director of the Center for Family and Community Health at the University of California, Berkeley, School of Public Health.

    "I would not allow children to use a cell phone, or I at least would require them to use a separate headset," Moskowitz said. "It seems fairly derelict of us as a society or as a planet to just disseminate this technology to the extent that we have without doing a whole lot more research of the potential harms and how to protect against those harms. Clearly, we need to learn a whole lot more about this technology."

    Some in the technology industry disagree.

    "The peer-reviewed scientific evidence has overwhelmingly indicated that wireless devices do not pose a public health risk," John Walls, vice president of public affairs for CTIA-The Wireless Association, said in a prepared statement.

    "In addition, there is no known mechanism for microwave energy within the limits established by the [U.S. Federal Communications Commission] to cause any adverse health effects," he said. "That is why the leading global heath organizations such as the American Cancer Society, [U.S.] National Cancer Institute, World Health Organization and the U.S. Food and Drug Administration all have concurred that wireless devices are not a public health risk."

    For the new study, Moskowitz and his fellow researchers in South Korea searched medical bases for the keywords "mobile phones," "cellular phones," "cordless phones" and "tumors" or "cancer." They included 23 case-control studies, involving 37,916 total participants, in their final analysis.

    When the studies were pooled, no risk was seen between mobile phone use and brain tumors, either benign or malignant. But a subgroup of studies that employed more rigorous methodology -- most conducted by the same research team in Sweden -- reported a harmful effect, whereas a set of less rigorous studies -- most funded by an industry consortium -- found a protective effect.

    Specifically, the more robust studies found that using a mobile phone for a decade or longer resulted in an 18 percent increased risk for developing a brain tumor.

    Some studies also showed that brain tumors were more likely to appear on the side of the brain where the cell phone was used.

    According to the American Cancer Society, nearly 21,000 malignant brain or spinal cord tumors are diagnosed in adults in the U.S. each year, while 3,800 such tumors are diagnosed in children.

    Moskowitz also believes that there's potential for harm to other areas of the body -- the genitals, for example -- when the phone is carried in a pocket.

    With so many people worldwide using cell phones, even a small risk could translate into many illnesses and deaths, he said.

    "We need to do a whole lot more research because the stakes are really high and there seems to be suggestive evidence that you better be careful about this, especially in children, who have developing tissue and smaller brain and skull sizes," Moskowitz warned.

    Subramaniam seemed to agree.

    "I do encourage people to use the speaker phone or a hands-free device if they can, and I definitely do not encourage children to use cell phones because then there's a much longer lifetime risk of exposure," she said.

    "In my opinion," she said, "the question remains unsettled -- and unsettled always carries with it likelihood that we might find an association."

    A report last year from the National Research Council, the main operating agency of the National Academy of Sciences and the National Academy of Engineering, and compiled at the request of the U.S. Food and Drug Administration, called for more research into the risks posed by long-term cell phone use, rather than the more commonly studied short-term risks. It urged that such research focus on the health of children, pregnant women and fetuses as well as workers subject to high occupational exposure.

    10月13日，星期二（每日健康新聞）--最新專項研究發現，使用手機與患腦瘤之間存在著微弱的潛在聯系。

    一項對有關這一主題的現有研究進行的回顧并沒看清二者之間的全部關系，回顧論文發表在網絡版的《臨床腫瘤學雜志》上。但是，針對這一大家都關注的問題，只有在應用更嚴格的研究方法時，潛在的危害才被發現。

    這一結論，加上以前相似的模棱兩可的研究結論，沒有給全世界四十億手機用戶一個明確的指示：如果存在風險的話，那么他們通話時的風險是什么？

    "我們對此不能做出任何明確的結論，"華盛頓特區隆巴爾迪綜合癌癥中心腦瘤分中心的專家，迪帕*蘇巴馬廉說，"但本次研究，還有以前所有的研究對于增加風險的觀點仍存疑慮。所以，經過這么多年的研究，我們仍沒有一個明確的答案。"

    "讓人擔心的是，質量更高的研究表明兩者之間的確有關聯。"她說

    這項研究的最早發起人，加利福尼亞大學伯克利分校公共衛生學院家庭及公共衛生中心主任，喬爾*莫斯科維茨說："風險明顯存在。"

    "我不讓孩子使用手機，或者起碼要求他們戴上耳機，"莫斯科維茨說，"作為社會或者說整個人類，在沒有做大量的潛在危害性及如何防范這些危害研究的情況下，就將這一技術推廣到現在這種程度，我們是極不負責的。顯然，關于這一技術我們需要了解的還很多。"

    技術行業不同意這種說法。

    美國無線通信與互聯網協會公共事務副會長，約翰*渥斯在一份事先備好的聲明中說："同業互查組織的科學證據一邊倒式地表明，無線電裝置不會給公共健康帶來危險。"

    "再說，已知機理沒有表明，在美國聯邦通信委員會設立的極限以內的微波能量會對健康造成不利影響，"他說，"這就是權威性全球衛生機構，如美國癌癥協會、美國國家癌癥研究所、世界衛生組織及美國食品與藥物管理局一致認為，無線電裝置不會給公眾健康帶來危險的原因。"

    對于新的研究，莫斯科維茨及其南朝鮮的同事們以"移動電話"、"蜂窩電話"、"無繩電話"以及"腫瘤"或"癌癥"為關鍵詞搜索醫學數據庫。他們總共進行了23次病例對照研究，總參加人數為37916人。

    匯總研究結果時，使用移動電話與患腦瘤（包括良性和惡性）之間的風險沒有被發現。但是采用更嚴格方法的一個從屬研究小組報告了有害作用，這些方法是由瑞典的同一個研究小組實施的。然而，一組由工業社團支助的缺乏嚴格性的研究卻發現了防護作用。

    明確地說，更精確的研究發現，使用手機十年以上，患腦瘤的風險增加18%.

    還有些研究表明，腦瘤更容易出現在腦部使用手機的一側。

    據美國癌癥協會報道，美國每年成人中近21000人被診斷為惡性腦瘤或脊髓腫瘤，有3800名兒童被診斷出此類腫瘤。

    莫斯科維茨還認為，把手機放在衣袋中，有可能對身體其它部位，如生殖器造成傷害。

    他說，世界上用手機的人如此之多，即使小風險也會帶來大量的疾病和死亡。

    蘇巴馬尼安贊成這種說法。

    她說："我鼓勵人們盡可能使用揚聲器電話或免提裝置。我當然不鼓勵兒童使用移動電話，因為如果這樣，那么他們一生中所冒的接觸風險則大。"

    "在我看來，問題仍懸而未決，但這總會帶來找到二者之間聯系的可能性。"

    莫斯科維茨警告說："我們必須做更多的研究，因為這個問題的風險太大。有證據提示，對此您最好保持謹慎，特別是兒童，他們的器官正在發育，頭骨和大腦都小。

    美國國家科學院和美國國家工程學院的主要營業機構――美國國家研究院應美國食品及藥物管理局的請求，去年編寫了一份報告。報告呼吁對長期使用手機構成的風險進行研究，而不要進行通常短期風險研究，此類研究要注重兒童、孕婦、胎兒以及遭受高職業照射量的工人的健康。