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（每日健康新闻）--最新专项研究发现，使用手机与患脑瘤之间存在着微弱的潜在联系。

    一项对有关这一主题的现有研究进行的回顾并没看清二者之间的全部关系，回顾论文发表在网络版的《临床肿瘤学杂志》上。但是，针对这一大家都关注的问题，只有在应用更严格的研究方法时，潜在的危害才被发现。

    这一结论，加上以前相似的模棱两可的研究结论，没有给全世界四十亿手机用户一个明确的指示：如果存在风险的话，那么他们通话时的风险是什么？

    "我们对此不能做出任何明确的结论，"华盛顿特区隆巴尔迪综合癌症中心脑瘤分中心的专家，迪帕*苏巴马廉说，"但本次研究，还有以前所有的研究对于增加风险的观点仍存疑虑。所以，经过这么多年的研究，我们仍没有一个明确的答案。"

    "让人担心的是，质量更高的研究表明两者之间的确有关联。"她说

    这项研究的最早发起人，加利福尼亚大学伯克利分校公共卫生学院家庭及公共卫生中心主任，乔尔*莫斯科维茨说："风险明显存在。"

    "我不让孩子使用手机，或者起码要求他们戴上耳机，"莫斯科维茨说，"作为社会或者说整个人类，在没有做大量的潜在危害性及如何防范这些危害研究的情况下，就将这一技术推广到现在这种程度，我们是极不负责的。显然，关于这一技术我们需要了解的还很多。"

    技术行业不同意这种说法。

    美国无线通信与互联网协会公共事务副会长，约翰*渥斯在一份事先备好的声明中说："同业互查组织的科学证据一边倒式地表明，无线电装置不会给公共健康带来危险。"

    "再说，已知机理没有表明，在美国联邦通信委员会设立的极限以内的微波能量会对健康造成不利影响，"他说，"这就是权威性全球卫生机构，如美国癌症协会、美国国家癌症研究所、世界卫生组织及美国食品与药物管理局一致认为，无线电装置不会给公众健康带来危险的原因。"

    对于新的研究，莫斯科维茨及其南朝鲜的同事们以"移动电话"、"蜂窝电话"、"无绳电话"以及"肿瘤"或"癌症"为关键词搜索医学数据库。他们总共进行了23次病例对照研究，总参加人数为37916人。

    汇总研究结果时，使用移动电话与患脑瘤（包括良性和恶性）之间的风险没有被发现。但是采用更严格方法的一个从属研究小组报告了有害作用，这些方法是由瑞典的同一个研究小组实施的。然而，一组由工业社团支助的缺乏严格性的研究却发现了防护作用。

    明确地说，更精确的研究发现，使用手机十年以上，患脑瘤的风险增加18%.

    还有些研究表明，脑瘤更容易出现在脑部使用手机的一侧。

    据美国癌症协会报道，美国每年成人中近21000人被诊断为恶性脑瘤或脊髓肿瘤，有3800名儿童被诊断出此类肿瘤。

    莫斯科维茨还认为，把手机放在衣袋中，有可能对身体其它部位，如生殖器造成伤害。

    他说，世界上用手机的人如此之多，即使小风险也会带来大量的疾病和死亡。

    苏巴马尼安赞成这种说法。

    她说："我鼓励人们尽可能使用扬声器电话或免提装置。我当然不鼓励儿童使用移动电话，因为如果这样，那么他们一生中所冒的接触风险则大。"

    "在我看来，问题仍悬而未决，但这总会带来找到二者之间联系的可能性。"

    莫斯科维茨警告说："我们必须做更多的研究，因为这个问题的风险太大。有证据提示，对此您最好保持谨慎，特别是儿童，他们的器官正在发育，头骨和大脑都小。

    美国国家科学院和美国国家工程学院的主要营业机构――美国国家研究院应美国食品及药物管理局的请求，去年编写了一份报告。报告呼吁对长期使用手机构成的风险进行研究，而不要进行通常短期风险研究，此类研究要注重儿童、孕妇、胎儿以及遭受高职业照射量的工人的健康。