Five ninth-grade students from northern Jutland, Denmark, used cress seeds to investigate a question that had begun with their own experience of mobile phones and sleep. Their classroom project attracted international attention, including interest from researchers in Europe. Its photographs offered a striking comparison between trays of seedlings, but the question of what caused the difference requires more than a visual contrast.
The attention surprised the students, who had begun with an everyday question rather than an international research programme. "I still can't believe it. It's really exciting and overwhelming. It's just not an everyday thing", says Lea Nielsen and Mathilde Nielsen, two of the students.
It all began when the girls found it hard to concentrate during a typical day at school. As Nielsen explains: “We all feel we have found it hard to concentrate in school if we had slept with our mobile beside our head. Sometimes we even found it hard to sleep”.
After this observation, the girls took 400 cress seeds and put them in twelve trays. They then put six trays in each of two different rooms at the same temperature. They decided to give the same amount of water and sun to all the trays for twelve days.
Nevertheless, six of the trays were placed beside two Wi-Fi routers. Wi-Fi and mobile communications both use radiofrequency electromagnetic fields, but that does not establish identical exposure. The feature reported poorer growth near the routers after twelve days; it did not provide genetic evidence for the claimed “mutations.”
Olle Johansson praised the project, and a possible follow-up with Marie-Claire Cammaerts was discussed.
That interest later led to a 2015 paper by Cammaerts and Johansson in Phyton, described by its authors as a preliminary replication study. They reported differences in cress germination under the exposure conditions they examined. This was further research on seeds, not a clinical test of Wi-Fi exposure in people.
In the coverage of the school experiment, Johansson said: “The girls stayed within the scope of their knowledge, skilfully implemented and developed a very smart experiment. The wealth of detail and accuracy is excellent, selecting cress was wise, and I could go on”.
Johansson also expressed an interest in working with the students and encouraged them to consider a future in research. "I firmly believe they have a natural aptitude for it. Personally, I would like to see them in my team!" , he adds.
The experiment did not prove that ordinary Wi-Fi use is dangerous to people. The students’ reported personal choices are not a clinical finding. After the experiment, the students said they had stopped sleeping with phones beside them. "Either the mobile is placed far away, or it is placed in another room. Also, the computer is always off”, says Lea.
The school project does not support a health recommendation to relocate a Wi-Fi router. Its design and the distinction between plant growth and human evidence are explained below.
References: Why Don't You Try This, Stop Smart Meters
The central issue is the comparison
The students’ curiosity is worth encouraging. The reported comparison does not isolate Wi-Fi exposure well enough to establish a cause of the growth difference, and a test of seedlings cannot establish a health effect in people. A difference between trays is the beginning of a question about causes, not the end of that investigation.
In particular, placing one exposure condition in one room and the other condition in another room ties the proposed treatment to the room. Any room-level difference could then travel with the treatment. Equal intended watering, light, and temperature are helpful aims, but they do not demonstrate that every relevant condition was measured and remained identical.
Six trays do not necessarily mean six independent exposure tests
If all six exposed trays share one room and all six comparison trays share another, the room is part of the experimental unit. Repeating measurements within a room does not remove a possible difference between the two rooms. A stronger design would need independent replication of the exposure comparison, with randomized placement and careful measurement of environmental conditions.
Scoring plant growth without knowing which treatment a tray received would also help reduce observer expectations. These are examples of design improvements, not allegations that any particular error definitely occurred. The available account does not provide enough detail to diagnose the actual cause of the reported growth difference.
Poor growth is not a genetic test
A photograph of damaged or poorly growing seedlings cannot establish a mutation. That word describes a genetic change and requires appropriate evidence. Even a well-replicated finding in cress would still need separate reasoning and research before being applied to human health.
The UK Health Security Agency’s Wi-Fi evidence summary, updated in 2025, reports no consistent evidence that Wi-Fi exposure adversely affects the health of the general population. That assessment should not be replaced by a viral school-project photograph, nor exaggerated into a claim that every conceivable exposure question has been settled forever.
The constructive lesson is how to improve a test. A compelling classroom question can lead to better controls, clearer measurements, and a more precise conclusion. Respecting the students’ interest in science means applying those standards to the claims made on their behalf.
For another student project whose claims need a defined scope, read Jack Andraka’s Cancer Sensor Project: Promise and Validation.
My computer tells me that if I had the codes to them all I have access to five additional WiFi routers in my neighborhood. I also have utility company smart meters outside my bedroom window. How harmful is this to my health?
ReplyDelete=
would be easier just to tell us what the cure is ..why would we have to call the number etc... bah sounds like a scam to me.
ReplyDeletehttp://www.snopes.com/cress-wifi-experiment/
ReplyDeleteAlthough anti-technology sites continue to present the claim as novel and credible, seasoned researchers almost immediately identified significant flaws in the methodology. At least one attempt was made to replicate the results of the teenagers’ research, but no information emerged between May 2013 and April 2017 to suggest it was ever determined that wifi definitively stunts the growth of cress, or any other plant.
Am really grateful and thankful for what Dr.Olori has done for me and my family. I Was having HIV/ AIDS for good three years with no solution, the diseases almost took my life and because I was unable to work and I was also loosing lots of money for medication, one faithful day when I went online, I met lots of testimonies about this great man, so I decided to give it a try , message him at he Email and he told me everything i need to do, then i did it because i wanted to be cured,to God be the glory he did it. he cured me of my diseases and am so happy right now ,if you want he help you have to message him at this Email Olorispellhome@dr.com. if you need his help or you also want to get cured just the way I got mine, go get your healing. He has cure for other deadly diseases like Diabetes, Herpes, Hepatitis of all types and Cancer..
ReplyDelete