Why Cell-Phone Health Concerns Persist

Why Cell-Phone Health Concerns Persist

Despite years of study, questions continue to be raised whether mobile phones can contribute to health problems

by Jay Yarow

Why can't we get a definitive answer about cell phones and health?

Mobile phones have been around for over 20 years, and they're now used by more than 3 billion people. Yet questions linger over whether mobile phones can contribute to health problems, including cancer. The most recent alarm came from the director of the University of Pittsburgh Cancer Institute, who warned school employees to limit their cell-phone use based on early unpublished data from scientific studies. "Although the evidence is still controversial, I am convinced that there are sufficient data to warrant issuing an advisory to share some precautionary advice on cell-phone use," wrote Ronald Herberman in a memo to 3,000 faculty and staff in late July.

To be clear, many studies have presented evidence that cell phones are safe. The wireless industry, from Nokia (NOK) and Motorola (MOT) to Verizon Wireless and AT&T (T), says there is no cause for concern. "The overwhelming majority of studies that have been published in scientific journals around the globe show that wireless phones do not pose a health risk," said the Cellular Telecommunications & Internet Assn., the wireless industry's trade group, in a statement following Herberman's memo.

Not Around Long Enough

But definitive scientific proof is tough to come by. One key reason is that people use their cell phones, by definition, in ways that make them hard to study. We make phone calls on the go, from the grocery store or in our cars. That makes it difficult to reap the precise details important to scientific study, like how long we used the phone or which side of the head it was pressed against. The topic also falls between areas of scientific study, with doctors expert in the human body on one side and engineers well versed in radio technology on the other. Finally, time is an issue. While cell phones have been around a while, they've been mainstream products for only 10 years or so, and it may take much longer than that for adverse effects to show up. "The most difficult thing to resolve is whether there is an effect with long-term mobile-phone use," says Rodney Croft, executive director at the Australian Center for Radio Frequency Bioeffects Research.

Consumers and scientists had hoped that an ambitious research project, due out later this year, to study the issue would overcome these limitations. The effort, called Interphone, is a decade-long study involving 13 countries. "It's time for the Interphone to come out. It's a public health issue," says Louis Slesin, author of Microwave News, a newsletter that tracks non-ionizing radiation research—the type cell phones emit.

Still, the slices of Interphone research that have been published recently (while the final report is being prepared) suggest that it won't be the definitive word, either. Interphone's research coordinator, Dr. Elisabeth Cardis, warns that "the interpretation of the data is not very clear." Slesin says that "Interphone will not be the last word. It is more a progress report."

Studying Tumor Risk

In February of this year, Japanese scientists participating in Interphone published partial findings, based on their research, in the British Journal of Cancer. They "observed no increase in overall risk of [tumors] in relation to regular mobile-phone use among our Japanese subjects."

While some experts hailed the research as providing evidence that mobile phones do not cause cancer, others dispute the conclusion. Bruce Hocking, an Australian doctor who specializes in occupational and environmental medicine, argues that the Japanese study had key flaws. In a letter to the Journal, Hocking said the Japanese gathered data that relied on people's ability to remember "cumulative length of use and cumulative call time," which "may be associated with random errors, leading to overestimation or underestimation of true usage." This is referred to as recall bias.

"It is hard for people to recall, accurately, their phone use over a 10-year period. Researchers want mobile-use records, but they are challenged by privacy rules," says Hocking. "The best way to research it is, prospectively, off billing data."

Closed Research Labs

But new studies on health and cell phones are tough to get going. In the U.S., most research on the topic was discontinued at the beginning of the decade, largely because industry groups and government considered the questions resolved and haven't been willing to finance new studies. "The U.S. had been the leading country in the research on radio-frequency radiation from the 1960s to the 1990s," says Dr. Henry Lai, a professor at the University of Washington who has studied research funding of the issue. Over time, however, "most labs in the U.S. that did research on electromagnetic fields closed down."

But scientists are concerned that cutting off studies could be a mistake. "It was 15, 20 years after people began smoking that we saw concerns associated with it," says Dr. Michael Kelsh, principle scientist and epidemiologist for Exponent, a scientific consulting firm. "Down the road, the same could happen with phones." He says that studying cell-phone usage requires time, because the latency period for brain tumors can be 10 to 15 years.

Dr. Michael Thun, vice-president of epidemiology and surveillance research for the American Cancer Society agrees that time is a concern, particularly with children using cell phones. "We haven't had long-term exposure with kids. There can always be surprises; we cannot say with 100% certainty that it is safe. It is just not clear yet."

Despite the ongoing concerns, Slesin cautions that people need not live in fear. "People should wear wired earpieces," he says. "I don't think people should stop using cell phones. I think people need to be aware that there is a risk."

Yarow is an intern at BusinessWeek.

为什么人们一直担心手机会危害健康

为什么人们一直担心手机会危害健康

尽管经过多年的研究，人们还是不断地在问：手机是否可能导致健康问题？

作者：吉艾.亚尔欧（Jay Yarow）

对手机和健康的关系，为什么我们得不到明确的答案？

手机面世已有二十年的时间了，现在手机用户超过了三十亿。但手机是否会引发包括癌症在内的健康问题？这一疑问仍时常引起人们的争论。最近的警告来自匹兹堡大学癌症研究院主任，基于以前未公布的科学研究数据，他警告学校员工要限制使用手机。“尽管各种证据仍有互相矛盾，我还是相信有充分的数据足以发布建议，分享关于手机使用的预防性忠告，”罗纳德.荷伯尔曼（Ronald Herberman）在七月底发给3,000名员工的备忘录中写到。

很明显，许多研究给出了使用手机是安全的证据。在无线通讯行业，不管是诺基亚、摩托罗拉，还是Verizon Wireless或AT&T，他们都声称没有理由要特别关注这一问题。“全球科学杂志上发表的绝大多数研究都显示，无线电话不构成健康风险，”无线行业贸易组织移动通信及互联网协会（the Cellular Telecommunications & Internet Assn）在针对荷伯尔曼（Herberman）备忘录的一份声明中表示。

问题出现时间的跨度还不足以作出最后结论

但是很难拿出明确的科学证据。按定义，一个关键的理由是，人们使用手机的方式使得研究比较困难。不管是在杂货店还是汽车里，我们在移动中打电话。这使得获取像用了多长时间的手机、通话过程用手机放在头的哪一侧这样的准确细节非常困难，而这些细节对科学研究相当重要。这一课题在科学研究领域的两个方面都没能得到解决，这里的一方是擅长人类身体研究的医生，另一方是精通于无线电技术的工程师。最终，时间成了个问题。虽然手机最近很普及，但它成为主流产品还只有十年左右的时间，使用产生的不良效果要显现出来，也许要花比这更长的时间。“最难以解决的问题是长期使用手机是否会对人体健康产生影响，”澳大利亚无线射频生物影响研究中心执行主任罗德尼.克洛福特（Rodney Croft）表示。

消费者和科学家都寄希望于为了研究这一问题而计划今年晚些时候开始的一项雄心勃勃的研究计划能战胜这些制约条件。该项目被称为Interphone，是一项涉及十三个国家为期十年的研究。“是开展Interphone项目进行研究的时候了。这是大众健康问题，”跟踪手机发射出的这类非电离辐射研究的《微波新闻》作者路易斯.思莱森（Louis Slesin）说。

然而，最近发布的Interphone研究的部份资料（最终报告正在准备之中）仍然暗示这也不是最终定论。Interphone计划协调员爱丽莎贝兹.卡尔迪斯（Elisabeth Cardis）博士警告“对数据的解释不是非常清楚。”思莱森（Slesin）说“Interphone将不是最终结论。它只是一份进展报告。”

研究导致肿瘤的风险

今年二月，参与Interphone的日本科学家根据其研究，在《英国癌症杂志》（the British Journal of Cancer）上发表了部份发现。他们“观察到，在日本国民中没有出现与经常使用手机行为相关的（患肿瘤）总体风险上升现象。”

在一些专家欢呼该研究提供了手机并不致癌的证据的同时，另外一些专家对此仍持异义。布鲁斯.哈克因（Bruce Hocking）是一名专攻职业病和环境医学的医生，他指出日本的研究存在一些关键的缺陷。在写给该杂志的信中，哈克因（Hocking）说，日本的研究收集数据靠的是人们记忆“累积使用长度和累积通话时间”的能力，“这也许与导致高估或低估真实使用情况的随机误差相关。”这涉及到回忆倾向。“人们要准确无误地回忆过去十年中的手机使用情况，这很困难。研究者需要手机使用记录，可他们受到隐私规则的挑战，”哈克因（Hocking）说。“研究这一问题的最佳方法可能是与账单资料脱勾。”

纷纷被关闭的实验室

不过，要开展健康与手机间联系的新研究很艰难。在美国，大多数关于该课题的研究这个十年刚刚开始时就终止了，很大程度上是因为行业组织和政府认为该问题已经解决了，不愿意出钱资助新的研究。“从十九世纪六十年代到九十年代，美国已经成为了射频辐射研究的领先国家，”对这一问题的资助情况进行了研究的华盛顿大学教授亨利.莱（Henry Lai）博士说。可是，随时间流逝，“美国从事电磁领域研究的大多数实验室都关闭了。”

科学家们担心中止研究可能是个错误。“在人们开始抽烟十五到二十年后我们才看到相应的危害，”科学咨询公司埃克珀恩特（Exponent）的首席科学家和流行病学家麦歇尔.凯尔斯（Michael Kelsh）博士说。“一段时间后，手机使用上也会出现同样的事情。”他认为研究手机使用需要时间，因为脑瘤的潜伏期为十到十五年。

美国癌症界（the American Cancer Society）流行病和监督研究副主席麦歇尔.商（Michael Thun）博士也同意时间很关键，特别是小孩子们使用手机。“我们没有研究小孩长期使用手机可能会产生的问题。生活中总是有惊喜；我们不能百分之百确定地说这很安全。这只是还不清楚罢了。”尽管持续的关注，思莱森（Slesin）告诫大家不必生活在恐慌之中。“我们应该用有线话筒，”他说。“我并不认为大家应该停止使用手机。我认为大家需要清楚使用中存在危险。”

亚尔欧（Yarow）是《商务周刊》的一名实习记者。