February 14, 2012

The Luddites ride again

Arguably my favourite moment in the movie X-Men comes toward the end, when Magneto has the X-Men trapped in the Statue of Liberty.

"Fry him," team leader Cyclops orders Storm, who controls weather.

"Oh, yes, a bolt of lightning into a huge copper conductor," retorts Magneto. "I thought you lived at a school?"

I get the same feeling as Magneto when I read this news article:

An Ontario teachers' union is calling for an end to new Wi-Fi setups in the province's 1,400-plus Catholic schools.

The Ontario English Catholic Teacher's Association says computers in all new schools should be hardwired instead of setting up wireless networks.

It also says Wi-Fi should not be installed in any more classrooms.

In a position paper released on Monday, the union—which represents 45,000 teachers—cites research by the World Health Organization.

Last year the global health agency warned about a possible link between radiation from wireless devices such as cellphones and cancer.

[Full Story]

I can only guess that there are no science teachers in the OECTA. There are so many things wrong with this statement that I hardly know where to begin.

Last year, the the International Agency for Research on Cancer (IARC), part of the UN's World Health Organization (WHO), designated radio-frequency electromagnetic fields as a Class 2B carcinogen [PDF]. This all sounds scary (and precipitated about the hysteria you would expect), until you know that Class 2B means an agent is "possibly carcinogenic to humans." Not is carcinogenic or is probably carcinogenic, but possibly, meaning " there is limited evidence of carcinogenicity in humans and less than sufficient evidence of carcinogenicity in experimental animals."1 In other words: there's no real evidence that an agent causes cancer, but some piece of data suggests a risk, so on the list it goes. The IACR isn't saying EM radiation causes cancer. They're saying there's no good evidence one way or the other. Other Group 2B agents include coffee, pickles, carpentry, and—the earth's magnetic field. (Ban it! Immediately!)

Had the union read further on the WHO's Web site, they might have come across this conclusion: "Despite extensive research, to date there is no evidence to conclude that exposure to low level electromagnetic fields is harmful to human health."2 As my elementary-school teachers banged into my head 30 years ago: Reading comprehension matters.

There are two kinds of radiation: ionizing and non-ionizing. Ionizing radiation is high-frequency radiation that is energetic enough to strip electrons from atoms—that is, it creates ions (and hence is ionizing), which are chemically reactive. Ionizing radiation includes ultraviolet, X-rays, and gamma rays—which is why you wear sunscreen on the beach and a lead apron in the hospital X-ray room: these wavelengths can cause tissue damage. Non-ionizing radiation includes visible light, infrared, microwaves, radio waves, and extremely low-frequency (ELF) waves. These frequencies are not energetic enough to ionize tissues, and exposure to them is generally safe.

Wi-Fi typically operates at a frequency of 2.4 GHz (though some newer, higher-speed routers might also operate at 5 GHz). This is well within the microwave range. "Aha," you might be thinking, "microwaves are dangerous! You can cook meat in a microwave oven, so just imagine what a wireless router or cellphone can do to you."

Of course it's true that high-powered microwaves (such as you would find in a microwave oven) are potentially dangerous, but not because of ionization. Rather, the cooking effect is caused by heat. The oven generates microwaves at about the same frequency as a Wi-Fi router (about 2.4 GHz), which pass through the food. Water molecules vibrate rapidly as they try to align themselves with this electrical field. Basically, this motion generates friction, and friction generates heat. The oven cooks food by boiling it, which is why you can make tea in the microwave, but not toast.

An inexpensive household microwave oven has a power rating of, say, 1000 watts. Some of that—let's say 400 W—goes to powering the microwave itself and eventually gets dissipated as heat. That leaves 600 W to cook your food—for example, to reheat a cup of coffee almost to boiling in about two minutes.

On the other hand, take a typical home Wi-Fi router, like the blue box everyone has, the Linksys WRT54G. Its default transmit power is 21 mW. Yes, milliwatts: 21/1000 of a watt. The microwave oven has nearly 30,000 times the power of the Wi-Fi antenna. It takes the oven 2 minutes to reheat your coffee; how long do you think it would take your router?

To add more perspective, a cellphone might typically have a transmit power of 1 watt. Your Linksys router transmits a little more than 1/50 of that power—and, unlike your phone, you don't hold it up to your head, so you're only receiving a tiny fraction of that tiny wattage.

Just one more comparison: If you stand outside in broad daylight, you will receive roughly 100 W of radiated power from the sun, nearly 4,800 times as much as the router can put out. In addition, visible light is of a much higher frequency than microwaves.

Wi-Fi doesn't sound so scary anymore, does it?

If the OECTA had argued that Wi-Fi should be banned in schools so as to restrict unauthorized access to the Internet during school hours, it would have been a sensible policy. Instead, the union decided to hitch its wagon to pseudoscience, and took the path of scaremongering instead of sanity. And for that, they are the proud recipients of the DIM BULB du jour. They share this coveted honour with Fred Gilbert, who instituted a campus-wide ban on Wi-Fi five years ago, during his tenure as president of Lakehead University in Thunder Bay. Ludditism is an equal-opportunity offender: once the separate schools and universities get on the bandwagon, you can't blame it on the publik skools anymore.


1 International Agency for Research on Cancer, IARC Monographs on the Evaluation of Carcinogenic Risks to Humans, Preamble, http://monographs.iarc.fr/ENG/Preamble/CurrentPreamble.pdf (accessed February 13, 2012), 23, emphasis in original.

2 World Health Organization, "What are Electromagnetic Fields?" http://www.who.int/peh-emf/about/WhatisEMF/en/index1.html (accessed February 13, 2012).