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Back to Contents of Issue: September 2002


Is the Keitai craze putting your health at risk by exposing you to untold radiation?

by Tim Hornyak
ON THE EVENING OF May 31, thousands of passengers became stranded in a JR Yamanote Line train that had halted between Yoyogi and Harajuku stations in Tokyo when a fire broke out in a building adjacent to Yoyogi. The blaze paralyzed a major part of the JR East rail network for hours, forcing the cancellation of 318 services and affecting 318,000 commuters during rush hour. The passengers on the stranded train were eventually guided to safety by JR officials.

According to research by Sendai's Tohoku University, the passengers on the loop line train were likely exposed to dangerous levels of electromagnetic radiation soon after it was halted. The source? Their own mobile phones.

A study by assistant statistical physics professor Tsuyoshi Hondou warns that trains can trap mobile phone radiation and levels can exceed international safety limits even if a small number of phones are being used. But the average train or subway car in Japan is chock-full of people using their keitai in one way or another.

When hundreds of passengers in a packed train dial others after an accident and tell them they'll be late, the resultant power of radiofrequency (RF) emissions would be comparable to the radiation generated by a microwave oven or a satellite broadcasting station -- well above the safety standard set by an affiliate of the World Health Organization called the International Commission on Non-Ionizing Radiation Protection (ICNIRP), according to Hondou.

In his article in the February edition of the Journal of the Physical Society of Japan, Hondou posits that the metals in a train carriage body reflect electromagnetic radiation, causing them to accumulate within to potentially dangerous levels.

"Conventional analysis is valid as long as there is only one mobile phone and also the boundary is not reflective," he states in the article. "These conditions are not appropriate for considering current situations."

Although some waves can escape through the windows, he illustrates the phenomenon with a room in which the interior is painted black and lit by a single, weak light bulb. Cover all the black areas with mirrors, and the inside gets brighter, he says, and the same electromagnetic laws apply to cellphone signals.

Mobile phone radiation physics is not Hondou's specialty. He was commuting on the JR Senseki Line one day and heard interference in his music player headphones. Wondering at the cause, he contacted the manufacturer of the device and was told it was electromagnetic waves emitted from nearby keitai. Finding nearly no studies in the literature on the accumulation of waves in an enclosed space, he derived a simple formula to predict their average strength. Then he applied it to the design of a typical commuter train car, which he says is made of metals that have nearly 100 percent wave reflectivity. He found that "the simultaneous use of a number of mobiles in an area with a reflective boundary creates a level of exposure which can exceed that stipulated in the ICNIRP guidelines."

Phones emit power as long as they are on, according to Hondou, who says he did not determine output in different modes because product characteristics often change and he was more concerned with analyzing the problem of radiation dissipation.

The article rekindled health concerns associated with mobile phone use in Japan and abroad, and recalls fears that electromagnetic fields around such emitters as high-voltage electrical wires may cause cancer. But several international experts as well as officials in Japan's Ministry of Public Management, Home Affairs, Posts and Telecommunications were skeptical of Hondou's findings.

"We believe that the article does not take into account the fact that the RF fields are absorbed by the sides of the carriage and by people in it," says Mike Repacholi, a coordinator for radiation and environmental health at the WHO in Geneva. "Thus, it would be extremely unlikely for a number of mobile phones being used in a train to cause people to be exposed to RF fields in excess of the international limits."



The view reflects a consensus among some authorities that RF fields have not been shown to cause any adverse health effects. However, a 1999 expert panel report by the Royal Society of Canada noted holes in current understanding, and added, "It is possible that users of wireless telecommunication devices, including cellphones, may experience exposures of sufficient intensity to cause biological effects, although these biological effects are not known to be associated with adverse health effects." A report the following year by Britain's Independent Expert Group on Mobile Phones even states, "It is not possible at present to say that exposure to RF radiation, even at levels below national guidelines, is totally without potential adverse health effects ... the gaps in knowledge are sufficient to justify a precautionary approach."

Hondou argues that while people use cellphones at their own risk, the public often has no choice when it comes to exposure to radiation, including those with pacemaker implants, which is one of the only subjects of keitai advisories in Japanese trains and subways.

He says he found through the study and the reaction to it that some electromagnetism experts and people in the Japanese government do not grasp the basics of the field and would fail an exam on it if they repeated their claims that RF waves will have negligible reflection if the walls of an area are far enough apart. He calls for further detailed studies on the matter as well as appropriate guidelines.

"Increasing public exposure to electromagnetic wave emission is a form of environmental pollution," he states in the study, "in both cases, naive personal consumption will lead to global pollution, which eventually may hurt humans." @

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