電磁場（EMF）
electromagnetic fields (EMFs)

電磁場とは、電流による力が働く場所のことである。

多くの人はEMFでガンになると恐れている；だがEMFとガンの因果関係が確立されているわけではない。事実、国立研究協議会（National Research Council, NRC）は３年以上かけて過去20年以上にわたって行われた科学研究500報以上を調査し、電磁場が人体に有害だとする“確固たる一貫性のある証拠”は見い出されなかったと結論づけている。NRC委員会の座長を務めた神経生物学者チャールズ・F・スティーブンス教授は、“本研究の結果、家庭で一般的に生じている電磁場が健康問題を引き起こすという確固たる証拠は見られなかった。また大規模な試験研究では、EMFがヒトの健康に有害なかたちで細胞に障害を与えるといったことは見られなかった”と述べている。

1997年、ニューイングランド医学雑誌（The New England Journal of Medicine）はEMFとガンの関係について今まで最大規模かつ最も詳細におこなわれた研究の結果を掲載した。この研究を指揮したマーサ・S・リネ博士は、こう述べている：“家庭レベルの磁場が小児白血病のリスクを増大させるという証拠は見い出されなかった。”この研究は８年間かけておこなわれたもので、送電線の近傍で生成される磁場への曝露計測まで含まれていた。15歳以下の急性リンパ性白血病を罹患している子供638人を、健常な子供620人と比較した。“本研究者らは、母体の妊娠期間中を含め、白血病が発見されるまで子供たちが５年以上生活していたすべての家屋の電磁場を測定した。”母体や子供たちが曝露したEMFを正確に知るのは不可能だとして、この研究は批判された。計測はすべて曝露後になされねばならず、曝露中のEMF強度は大きくは変動しないと仮定せねばならないのだ。だが、妊娠から幼少期を通じてEMFへの曝露をシステマチックに制御した対照研究など、ナチスの医師ヨゼフ・メンゲルの知的伝統を受け継ぐ連中を除けば、やったりしないだろう。

それでもなお、多くの人は送電線の近くに住んだり携帯電話を使うとガンになると信じている。なぜだろうか？ある種の弁護士やマスメディア、それに科学に無知な大衆がこうした栄誉を担っている。

ロバート・プールは、EMFに反対する一般的見解は雑誌ニューヨーカーといった非科学的な情報源によって喚起されたと主張している (Pool, 1990)。同様な見解の喚起は、ラリー・キングといったトークショーのホストによってなされた。キングは、妻を脳腫瘍で失ったのは携帯電話が輻射するEMFが原因だと主張する男やもめを全国に紹介した。当然、裁判となった。証拠？腫瘍は電話を当てる耳の近くにあったのだ。主要テレビネットワークは裁判や脳腫瘍と携帯電話についてレポートした。話に‘深み’と信憑性を与えるため、科学者がインタビューされた。だがEMFとガンの間に因果関係を見い出した科学者はいないし、それは携帯電話と脳腫瘍の間ではなおさらだ。したがって、すでに生じている腫瘍をEMFに曝露させた科学者が、インタビューを受けた。彼は、EMFに曝露されると腫瘍の肥大が促進されると自分の研究が示していると報告した。携帯電話の売り上げは落ち、携帯電話を生産している企業の株価も下落した。EMFに曝露した腫瘍の肥大が促進されるからといって、EMFが悪性・良性いずれであれ、腫瘍の原因になるということを示すわけではない。

携帯電話が脳腫瘍の原因になっているという可能性はあるが、その可能性は小さい。携帯電話が輻射するEMFは非常に弱く、曝露も断続的なものだ。脳腫瘍の人が携帯電話を使用するのは危険性が高いという可能性はあるだろう。携帯電話を使わない場合と比較して、腫瘍の肥大が促進されるだろうからだ。しかし今のところ、いずれの可能性についても、それらを合理的に裏づける証拠はない。

Lawyers representing claimants who blame their cancers on power lines cite a Swedish study that found leukemia rates were 400% higher among children living near power lines. Another study, done by the University of Southern California, found increased leukemia rates in children living near power lines. According to Robert Pool,
 

The study examined 232 leukemia patients under than age of 10, and a group of control subjects that were matched for age, sex, and race. The amount of EMF exposure for each child was determined in a number of ways. No correlation was found between the incidence of leukemia and the electric field exposure as measured by spot checking. An insignificant correlation was noted between incidence of leukemia and levels of exposure to magnetic fields, as measured by a continual measurement over a 24-hour period. A significant correlation was seen between the EMF exposure, as measured by wire coding, and an increased risk of leukemia. Those with the highest level of exposure had a 2.5-fold greater risk of developing leukemia. It is not understood how these differences in correlation depend on the way the EMFs are measured. It is possible that some types of EMF exposure may lead to an increased risk of leukemia. On the other hand, measurements taken by wire coding may be more sensitive. Further study is needed to see what factors are being measured by the wire coding and not by the other methods. Until that is understood, it is not clear if exposure to high levels of EMFs is related to an increased risk of leukemia. (Pool, 1991)

Also, Pool reports, "there have been numerous scientific reports of elevated levels of leukemia in people who are exposed to high EMF levels on the job, such as power-line repairmen and workers in aluminum smelters." While the scientific jury is still out on the causal connection, if any, between living near power lines and cancer, the lawsuits are starting to come in. Over 201 challenges to utility projects were made in 1992 in which EMF was an issue. At least three suits have been filed in federal courts claiming exposure to utility lines caused cancer [Pool, 1991]. Utility companies are running scared. They are pouring billions of dollars into efforts to cut EMF exposure from their power lines. Dr. Robert Adair, a physicist at Yale University, calls the reaction "electrophobia" and says that it would take EMF levels 150 times higher than those measured by the Swedish researchers to pose a hazard.

Lawyers will be able to take their cases to court long before the scientific evidence is anywhere near conclusive. And the standards of proof in a court of law are appallingly much lower than those in science. For example, a few years ago Judith Richardson Haimes of Philadelphia was awarded more than $1 million by a jury because they believed she lost her psychic powers after having a CAT scan performed on her at Temple University Hospital. (A judge later reduced the award to $1, which is probably 98 cents more than her psychic powers were worth.) "All it's going to take is one or two good hits and the sharks will start circling," says Tom Ward, a Baltimore attorney who is suing Northeast Utilities Co. and its Connecticut Light & Power Co. unit over an alleged EMF cancer.[ibid.] There is currently a great push to bury all power lines. Better safe than sorry? The cost goes up twenty-fold to bury the lines. Then what? Lawyers claiming their clients' cancers were caused by EMFed water? It was bad enough trying to sell a house with power lines nearby when people cared about the ugliness of the view. But try to sell the same house when people are afraid of getting cancer from the ugly lines! In any case, we will have to bury our electrical wires even deeper than our power poles are high if we are to make a significant difference in shielding us from the magnetic fields of power lines.

It is not very likely that the average person has anything to worry about from power lines. Most of us do not get that close to them to be significantly affected by their EMFs. Our exposure to them, even if they are nearby, is not direct, up close and constant. We're probably in more danger of EMF pollution from the wiring in our homes and the electrical appliances we use, than from the wires overhead. No one can avoid electromagnetic radiation. It is everywhere. Furthermore, "while electrical fields are easily screened, magnetic fields make their way unimpeded through most substances" (Pool, 1990). In fact, it is curious that while fear of EMFs is on the rise so is the use of magnets to cure just about any ache or pain.

 The scientific evidence supports the view that we're not in much danger in our homes if our wiring is properly insulated. Yet, because utility companies fear lawsuits we are all likely to pay higher utility fees to cover the billions extra it will cost to put wires underground. If the utilities lose lawsuits, it's the shareholders who lose money and they don't want that. On the other hand, utility rates are generally set by public commissions, and these commissions might argue that the rate hikes are unwarranted because there is no proven hazard from EMFs. Utility companies may be forced to be advocates for the "electrophobes" in order to justify raising rates to cover the cost of putting lines underground to avoid the cost of lawsuits. Make no mistake about it: when the lines go underground it will be to avoid lawsuits, not to save lives or prettify urban neighborhoods.

further reading

• Study: no clear proof electromagnetic fields pose health risk
• Study: Leukemia risk no higher near power lines
• Powerlines and Cancer FAQs: Bibliography
• Static Electric and Magnetic Fields and Cancer FAQs
• EMF Link

Edwards, Diane D. "Cells Haywire in Electromagnetic Field?," Science News, v. 133, n. 14 (April 2, 1988).

Livingston, James D. Driving Force: The Natural Magic of Magnets (Harvard University Press, 1997). $11.96

Pool, Robert. "EMF-Cancer Link Still Murky," Nature, v. 349, n. 6310 (Feb 14, 1991).

Pool, Robert. "Is there an EMF-cancer connection?," Science, v. 249, n. 4973 (Sept 7, 1990), pp. 1096-1099.

Richards, Bill.  "Elusive Threat: Electric Utilities Brace for Cancer Lawsuits Through Risk is Unclear/ Companies Spend on Cutting Electromagnetic Fields as Lawyers Smell Blood," The Wall Street Journal, February 5, 1993, p. 1.

Sagan, Leonard A. "EMF Danger: Fact or Fiction?," Safety & Health, v. 145, n. 1 (Jan, 1992), pp. 46-49.

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