Evidence "increasingly against" phone cancer risk

By Ben Hirschler

LONDON | Sun Jul 3, 2011 10:23pm EDT

(Reuters) - Despite a recent move to classify mobile phones as possibly carcinogenic, the scientific evidence increasingly points away from a link between their use and brain tumors, according to a new study on Saturday.

A major review of previously published research by a committee of experts from Britain, the United States and Sweden concluded there was no convincing evidence of any cancer connection.

It also found a lack of established biological mechanisms by which radio signals from mobile phones might trigger tumors.

"Although there remains some uncertainty, the trend in the accumulating evidence is increasingly against the hypothesis that mobile phone use can cause brain tumors in adults," the experts wrote in the journal Environmental Health Perspectives.

The latest paper comes just two months after the World Health Organisation's (WHO) International Agency for Research on Cancer (IARC) decided cellphone use should be classified as "possibly carcinogenic to humans."

Anthony Swerdlow of Britain's Institute of Cancer Research, who led the new review, told Reuters the two positions were not necessarily contradictory, since the IARC needed to put mobile phones into a pre-defined risk category.

"We are trying to say in plain English what we believe the relationship is. They (IARC) were trying to classify the risk according to a pre-set classification system," Swerdlow said.

Other things deemed by the IARC to be possibly carcinogenic include items as diverse as lead, pickled vegetables and coffee.

Mobile phone use has risen hugely since the early 1980s, with nearly 5 billion handsets in use today, and controversy about their potential link to the main types of brain tumor, glioma and meningioma, has never been far away.

The largest study to date, published last year, looked at almost 13,000 mobile phone users over 10 years.

Swerdlow and colleagues analyzed its results in detail but concluded it gave no clear answer and had several methodological problems, since it was based on interviews and asked subjects to recall phone use going back several years.

Significantly, other studies from several countries have shown no indication of increases in brain tumors up to 20 years after the introduction of mobile phones and 10 years after their use became widespread, they added.

Proving an absence of association is always far harder in science than finding one, and Swerdlow said it should become much clearer over the next few years whether or not there was any plausible link.

"This is a really difficult issue to research," said David Spiegelhalter, Winton Professor of the Public Understanding of Risk at the University of Cambridge, who was not involved in the study.

"But even given the limitations of the evidence, this report is clear that any risk appears to be so small that it is very hard to detect -- even in the masses of people now using mobile phones."

Swerdlow is chairman of the International Commission on Non-Ionizing Radiation Protection's Standing Committee on Epidemiology. The commission is the international body, recognized by the WHO, that constructs guidelines for exposure limits for non-ionizing radiation.

Since mobile phones have become such a key part of daily life -- used by many for websurfing as well as talking -- industry experts say a health threat is unlikely to stop people using them.

(Reporting by Ben Hirschler; Editing by Will Waterman)





携帯電話による発がんリスク説、科学的証拠なし＝調査

2011年 07月 4日 14:05 JST

　［ロンドン　２日　ロイター］　携帯電話の電磁波で脳腫瘍が引き起こされる恐れがあるとの報告が先に世界保健機関（ＷＨＯ）から出されたが、英国と米国、スウェーデンの研究者で構成する専門家委員会は、「携帯電話による発がんリスク説」に科学的証拠はないとの調査結果を発表した。

　２日に学術誌「Environmental Health Perspectives（原題）」に掲載された論文で同専門家委員会は、過去に報告された調査の大規模な見直しを行ったところ、携帯電話の使用とがんの関係を示す有力な証拠は何もなかったと結論付けている。

　また、携帯電話からの電磁波が腫瘍を引き起こす恐れがあるとの説についても、確固たる生物学的メカニズムは見つかっていないと指摘。「いくつかの不明点は残っているが、これまで蓄積された証拠では、携帯電話の使用が成人の脳腫瘍を引き起こす可能性があるとの仮説に反する傾向がますます強まっている」としている。

　ＷＨＯの専門組織である国際がん研究機関（ＩＡＲＣ）は先に、携帯電話の使用について、５段階で示される発がんリスクのカテゴリーで、上から３段階目となる「発がん性が疑われる（possibly carcinogenic）」に位置づけていた。

　ただ、今回の調査を率いた英国がん研究所のアンソニー・スウェドレー氏は「われわれは（携帯電話とがんの）関係を平易な言葉で表そうとしている一方、ＩＡＲＣは既存のカテゴリーによるリスク分類を試みている（という違いがある）」と説明。調査結果とＩＡＲＣの見解は必ずしも相反するものではないとしている。

　携帯電話は現在、世界全体で約50億台が使われており、電磁波が脳腫瘍を引き起こすリスクがあるとの論争は賛否両論が絶えない。しかし、業界専門家らは、すでの日常生活に必要不可欠な存在となっている携帯電話を、健康リスクだけを理由に消費者が使わなくなることはないとみている。