Lately there’s some strange claims doing the rounds on internet and in the media about students finding some adverse effects of Wi-Fi on plant development, cress in this case. It’s very strange that Wi-Fi affected the plants as studies show that Wi-Fi is safe as there’s just not enough energy available in the signal being sent. Which means that what the high school students observed isn’t due to the Wi-Fi signal.
Still this didn’t stop the media spending too much attention on this. And of course pseudo-science websites like Natural News used it (archived here) to bolster their unsupported claims that Wi-Fi is dangerous. Lets start with what Natural News says about the reason the student got interested in researching this:
The experiment began when the five students realized that they had difficulty concentrating in school if they slept near their mobile phones the previous night. Intrigued by this phenomenon, the students endeavored to study the effects of cellphone radiation on humans.
I have a very simple explanation for why they wouldn’t be able to concentrate well in school: they didn’t sleep as well with the phones in their bedrooms as without them.
The probably causes for why they didn’t sleep as well is why I also never have my mobile phone in my bedroom. Depending on the model you have and the settings you use a phone can make noises, you could hear the vibrate function, the screen could temporarily light up, or it has other light sources. All that can disturb you during your sleep or make it harder for you to fall asleep.
Another factor is that when you have your phone in your bedroom it is very tempting to use it while you should be sleeping. Looking at a bright screen will make it harder for you to fall asleep or will wake you further. All these points I just raised are far more likely causes for not being able to concentrate as well the next day. Which has nothing to do with the very weak Wi-Fi signal you phone receives and sends (more on this later).
However, I’m assuming that what the students experienced is a real phenomenon and not for example them thinking they can’t concentrate as well. The medical literature is filled with examples of people thinking they are affected by something when it’s just them thinking this. The effects can be real, but it’s caused by you thinking it has a bad effect on you (it’s the opposite of the placebo effect, it’s called the nocebo effect).
As this was a high shool experiment for a science fair the students didn’t have the resources to test if their concentration issue was due to the Wi-Fi signal. So they switched to using cress as their test subjects:
The girls placed six trays of Lepidium sativum seeds (a garden cress grown commercially throughout Europe) in a room without radiation, and an equal amount in a room next to two Wi-Fi routers. Over a 12-day period, they observed, measured, weighed and photographed the results. Even before the 12th day arrived, however, the end results were obvious: The cress seeds placed near the routers either hadn’t grown or were completely dead, while the seeds placed in the radiation-free room had blossomed into healthy plants.
Sounds dramatic, doesn’t it? The pictures certainly look dramatic:
But here’s someone else already noticed about how the experiment was conducted:
The WiFi and control group were not just different because of the presence of the routers. On the pictures in the report it can be seen that also the laptops in the WiFi group were placed quite near to the plates. It’s very likely that this had an effect on airflow and temperature around the plates and that could have an effect on germination, which has nothing to do with the presence of EM-fields.
Details like this can really affect how well and how fast cress germinates. He also points out another quite important detail from the report the students wrote:
The reports on blogs illustrated the difference in germination by photographs of plates with cress, one showing a full grown, not radiated, ‘healty’ one and a plate which almost doesn’t show any sprouted seed at all, a radiated, ‘sick’ plate. If you look at the actual reported results, they do not look that shocking: on average the control group had 332 sprouted seeds versus 252 in the WiFi group.
The article contains far more and I recommend reading it for a better understanding of the issues with the research the students did. But I’d like to add something else, the amount of energy involved.
A Wi-Fi signal is broadcast at 2.4GHz, consumer microwave ovens usually use a frequency of 2.45GHz to heat food (for simplicity I’m leaving out the 5GHz signal modern Wi-Fi equipment also can use). Most consumer grade Wi-Fi electronics usually don’t go beyond 1 to 3 Watts, that’s more than enough to do the job. With the right equipment you can already get a Wi-Fi signal 420 km (260 mi) with just 6 Watts. Your microwave works at hundreds of watts and that just heats your food. The only reason there’s shielding in your microwave is to prevent it from burning you.
That’s why you shouldn’t worry about the Wi-Fi signal in your homes. It’s harmless as it just doesn’t have the energy to harm you, which is exactly what scientists found when they studied this. One high school experiment doesn’t change the results from those robust studies.