Tuesday, June 03, 2008

Double blind wins again

...but will it make a difference? No.

Are some people sensitive to mobile phone signals? (BMJ. 2006 April 15; 332(7546): 886–891.). Short answer, "No".
Long answer from the abstract:
Objective: To test whether people who report being sensitive to mobile phone signals have more symptoms when exposed to a pulsing mobile signal than when exposed to a sham signal or a non-pulsing signal.

Participants: 60 “sensitive” people who reported often getting headache-like symptoms within 20 minutes of using a global system for mobile communication (GSM) mobile phone and 60 “control” participants who did not report any such symptoms.

Intervention: Participants were exposed to three conditions: a 900 MHz GSM mobile phone signal, a non-pulsing carrier wave signal, and a sham condition with no signal present. Each exposure lasted for 50 minutes.

Results: Headache severity increased during exposure and decreased immediately afterwards. However, no strong evidence was found of any difference between the conditions in terms of symptom severity. Nor did evidence of any differential effect of condition between the two groups exist. The proportion of sensitive participants who believed a signal was present during GSM exposure (60%) was similar to the proportion who believed one was present during sham exposure (63%).

Conclusions: No evidence was found to indicate that people with self reported sensitivity to mobile phone signals are able to detect such signals or that they react to them with increased symptom severity. As sham exposure was sufficient to trigger severe symptoms in some participants, psychological factors may have an important role in causing this condition.
I.e., once they thought they were being exposed to electromagnetic waves, they got a headache. QED for psychosomatic symptoms and the nocebo effect.

Back to my first point. Does this fairly conclusive and simple study make a difference?
A group in Santa Fe says the city is discriminating against them because they say that they're allergic to the wireless Internet signal. And now they want Wi-Fi banned from public buildings. Arthur Firstenberg says he is highly sensitive to certain types of electric fields, including wireless Internet and cell phones.
What is the journalistic and legalistic take on this?
The city attorney is now checking to see if putting up Wi-Fi could be considered discrimination.
Here's an idea. What about checking to see if there's any evidence for this "disability", beyond a psychosomatic response? If it's not a real physiological problem, then legally, there is no problem. Moreover, we might get to the truth of the matter. (I guess I can't expect this to be the motivation of a journalist of lawyer, can I...) Given the credulous reporting of this story, and similar stories, I won't be at all surprised if electrical sensitivity becomes a factoid.

It's not as if the evidence isn't two words away. The paper I linked to is the first peer reviewed double blind trial I found using google scholar which looked at "electromagnetic sensitivity". One hopes if it gets to court, the lawyers will give google a crack.

Here's an even better solution. The city of Santa Fe could label all their WiFi points as "natural" and "organic". That'd do the trick. Or they could offer all the sensitive people "tin-foil deflector beanies". They combat mind control too! (Although there is evidence these might amplify some signals.)
Hat tip SGU for the Santa Fe story.