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Wifi experiment on cress growth

In 2012, there was great fuss about a small research paper of Danish students adressing the, supposedly great negative influence of radiation from Wi-Fi routers on the germination of cress. In the Danish Wi-Fi plant experiment, huge differences were observed between cress grown within the influence of a router vs a similar setup that had none. We tried to do a partial reproduction of the experiment to see to what end we could reproduce the results.

Research Question

The research question for this experiment has been defined as:

To what extent can we reproduce the results of the previous experiment on the effect of WiFi on the development of cress?

Test setup

For this experiment we created a test setup by putting a tray with cress seeds on an active router and a similar tray 4 ft away from it. Note that, during the entire experiment, the router has had active Wi-Fi tranmission on both the 2.4GHz and 5GHz band.

Criticism

Some criticisms on the original research are taken into account for this experiment:

  • In the Danish school, there was word of heat production by laptops. We’ve reduced this effect by not having a laptop anywhere near the setup.
  • We have tried to make the two trays to be in the exact same conditions except for the presence of the router.
  • Each day, 15 ml of water was added in both packages.
  • Both trays received the same amount of light.
  • Wi-Fi activity on both channels, with a minimum of 16 hours a day.

Factors besides radiation that have not been overcome

  • The heat production by the router. This could potentially causes the temperature to rise in the seed tray. Water could have been evaporating more quickly which may have had a negative effect on the germination.
  • The bottom of the seed tray on the router is much darker than the other one. Through the glass-bottom of the containers used, the germination could certainly be influenced. After all, we have already seen that the influence of light is enormous on cress growth.

100 cress seeds per tray

Both containers are filled with a few layers of paper towels and 100 cress seeds. Every day, approximately 15 ml of water was added to the trays.

The experiment

Wi-Fi experiment setup day 0

Wi-Fi experiment setup day 6

Results day 6

Day 6 – At a distance from router

Day 6 – Placed on the router

Observations

We can see the cress without the router grows clearly better. However, it would be an easy conclusion to write this effect direct full path to electromagnetic radiation of the wifi signal.

External factors

Factors that may be, affect, and are not excluded in this experiment are, for example:

  • Router produces heat, therefore creating a less favorable (?) germination temperature.
  • With this higher temperature water can evaporate faster and therefore the seeds could have had less water to grow with, causing unfavorable germination possibilities.
  • Efforts were made to keep the factor ‘light’ as neutral as possible, however it can not be ruled out that the cress is affected by the “black floor” due to the router.

Conclusions

There seems to be a clear negative effect on the development of cress by the router. However, there are still too many factors outside the Wi-Fi radiation that can also affect the results. The tray with cress sprouts on the router is easily a few degrees warmer. We can conclude that there are negative effects of the router but that is probably not due to Wi-Fi radiation.

So we can say we kind of reproduced the original Danish results a bit but we do not think this is due to radiation.

Wifi experiment on cress growth In 2012, there was great fuss about a small research paper of Danish students adressing the, supposedly great negative influence of radiation from Wi-Fi routers on

Wi-fried: do wireless routers really kill plants?

Electromagnetic radiation from a wireless router is unlikely to be strong enough to have any effect on living tissue. Photograph: Denis Closon/Rex Features Photograph: Denis Closon/Rex Features

Electromagnetic radiation from a wireless router is unlikely to be strong enough to have any effect on living tissue. Photograph: Denis Closon/Rex Features Photograph: Denis Closon/Rex Features

Last modified on Wed 14 Feb 2018 20.52 GMT

You may have seen in the Daily Mail on Monday (well, you MAY read the Daily Mail, who am I to judge?) the headline “What’s wifi doing to us? Experiment finds that shrubs die when placed next to wireless routers”.

Really? This is a bit worrying if so. What shrubs? Well, read a bit further down and the answer may surprise you: cress. I didn’t realise cress was a shrub, but you live and learn eh?

Apparently the researchers (some 15-year-old schoolchildren, in a classroom experiment in Denmark), decided to run the experiment after noticing they had trouble concentrating the morning after sleeping close to their mobile phones.

Quite why wi-fi got blamed for this, I’m not wholly sure, since the wi-fi in their rooms is unlikely to change depending on how close they are to their phones, but anyway, on we go.

Details about what they actually did are sketchy, but what’s been reported is that they put six trays of cress in a room near a wi-fi router, and six trays in a different room without a router. Then they reported what had happened to the cress 12 days later.

This article mentions that the rooms had equivalent light and the seeds were given equal amounts of water, which is great, but it’s unlikely that these students would have had the resources to truly monitor that conditions were equivalent in each room.

I think it’s unkind of me to criticise the experiment too much though. After all, this was a classroom study, and as such is frankly a great design, for that environment. But that certain mainstream media have leapt on this to scaremonger that wi-fi might be damaging our brain is nonsense. This experiment is not controlled enough to give us any evidence for that (and also, I’m not quite sure how similar human brains are to cress anyway).

The suggestion by scientists interviewed about the research is that routers give out heat, and this probably dried out the cress in the rooms with the routers in, so equivalent water was not enough for them.

As for why the girls might struggle to concentrate the day after sleeping with their mobile phones on their bedside, perhaps the lure of late-night Facebook sessions or internet procrastination means they sleep less well? There have been suggestions that the light from mobile phones or tablets just before bed can disrupt sleep patterns, although again there’s not really any strong evidence for this.

Mobile phones, wi-fi and the like are going to cause controversy; almost all new technology does. But wi-fi signals are not strong, you would have to go around with a router strapped to your head for extended lengths of time to be exposed to any meaningful level of electromagnetic radiation.

One thing I’d like to say though to the young women who conducted this experiment, is PLEASE don’t listen to people like me writing critiques of your experiment! I am not criticising what you did at all, because I think it’s great. What I think is dangerous and unhelpful is the media reporting schoolroom science in the same style as well-controlled peer-reviewed research, and claiming it provides the same strength of evidence.

I completely agree with this quote from Olle Johansson at the Karolinska Institute (taken from this article):

The girls stayed within the scope of their knowledge, skilfully implemented and developed a very elegant experiment … I sincerely hope that they spend their future professional life in researching, because I definitely think they have a natural aptitude for it.

Some students in Denmark did a school experiment and found cress growing near wi-fi routers went brown. Cue hysteria …