Cell phone studies find no 'consistent evidence' of cancer link(2002)

A review of cell phone studies commissioned by the Swedish Radiation Protection Authority has found no "consistent evidence" of an increased risk of cancer from usage, the agency said.

Studies have differed on whether the use of mobile phones increases the risk of cancer as the handsets have become increasingly popular and efficient.

The governmental agency asked Dr. John D. Boice Jr. and Dr. Joseph K. McLaughlin of the International Epidemiology Institute in Rockville, Md., to evaluate published epidemiological research on the subject.

The review looked at nine studies since 1996 that included factors such as type of phone, duration and frequency of use and brain tumor location.

"No consistent evidence was observed for increased risk of brain cancer (or other forms)," the scientists said in the review, released Wednesday.

The agency acknowledged public concern about the issue and said many studies were still being performed and continued follow-up was needed on any possible carcinogenic effect linked to mobile phone usage.

"You can never say that something is without risk, but at least we can say that there is no scientific evidence for a causal association between the use of cellular phones and cancer," said Lars-Erik Paulsson, a radiation expert with the agency.

The review singled out research by Swedish oncologist Lennart Hardell, which said that long-term users of old-fashioned analog cell phones were at least 30% more likely than nonusers to develop brain tumors. Newer digital phones emit less radiation than older analog models of the sort studied.

Hardell, whose study was published recently in the European Journal of Cancer Prevention, studied 1,617 patients with brain tumors and compared them with a similar-size group of people without tumors.

The review said Hardell's study and some U.S. research with similar findings were "non-informative, either because the follow-up was too short and numbers of cancers too small, or because of serious methodological limitations."

It contrasted those with three studies in the United States, and studies in Finland and Denmark, which Paulsson said used more reliable sampling methods and were based on medical reports rather than interviews with patients.

Those studies found "a consistent picture ... that appears to rule out, with a reasonable degree of certainty, a causal association between cellular telephones and cancer to date," the agency said.

最近,由瑞典辐射保护研究所组织进行的一份研究显示,目前尚没有任何"直接证据"表明使用手机会增加癌症的患病几率。

在学术界，关于手机的广泛使用到底会不会增加癌症的患病率这一课题的争论由来已久，但一直都没能得出一致的结论。

作为政府的官方机构，瑞典辐射保护研究所从美国马里兰州罗克维尔的国际流行病研究所请来了约翰·D·布瓦斯·Jr和约瑟夫·K·麦克劳克林两位教授，对目前研究这一课题的众多出版物进行了综合性评估。

两位科学家共分析了1996年以来的9份研究报告，其中包括手机的种类，使用寿命及频率，甚至还有脑部肿瘤通常所在的位置等。

在9月16日公布的研究结果中，他们的结论是："目前还没有发现使用手机和引发脑癌（及其他癌症）之间有任何直接的必然联系。"

考虑到民众对这一问题的普遍关注，瑞典辐射保护研究所表示，他们还将继续这一课题的研究，跟踪调查手机使用中可能产生的所有致癌物质。

研究所的一位辐射专家拉尔斯-埃里克·保尔松指出："不能肯定这（使用手机）绝对没有危险性，但至少我们现在可以说用手机和得癌症之间没有必然的直接联系。"

这份报告中还专门以瑞典肿瘤科医生伦纳特·哈德尔的调查为例进行了分析。哈德尔的调查认为长期使用老式模拟手机的人患脑癌的可能性要比不用手机的人高至少30%。而新型数字机的辐射则要比老式模拟机少得多。

哈德尔共研究了1617名脑癌患者，并将他们的与人数差不多的非脑癌患者进行了比较。他的研究刊登在最近的《欧洲癌症预防》杂志上。

和哈德尔一样，另一些美国科学家的研究也得出了类似的结论。但研究所的分析认为，他们的调查"信息不够充分"，一方面跟踪调查的时间太短，癌症患者的人数太少，另一方面调查方法也存在着局限性。

研究所的分析将他们的调查与另外三位分别来自美国、芬兰和丹麦的科学家所作的调查作了对比。认为这三位的调查进行了更可信的取样，并且是以医学报告为依据，而不仅仅是简单地采访一些病患者。

因此，研究所得出了这样的结论：这三份调查的一致结果更为可信，它们用科学的分析排除了用手机和得癌症之间的直接、必然联系。