Below a certain threshold value, electrosmog has no impact on biological processes or even human health – that was the state of scientific knowledge up to now. But for the first time, a research team led by Prof. Dr. Henrik Mouritsen, a biologist and Lichtenberg Professor at the University of Oldenburg, has been able to prove that the magnetic compass of robins fails entirely when the birds are exposed to AM radio waveband electromagnetic interference – even if the signals are just a thousandth of the limit value defined by the World Health Organization (WHO) as harmless.
The findings based on seven years of research by nine Oldenburg scientists, in cooperation with Prof. Dr. Peter J. Hore of Oxford University, are now available in a paper entitled "Anthropogenic electromagnetic noise disrupts magnetic compass orientation in a migratory bird", published in the latest issue of the renowned scientific journal Nature. Nature underlines the importance of this study by making it the cover story of its May 15th issue.
"In our experiments we were able to document a clear and reproducible effect of human-made electromagnetic fields on a vertebrate. This interference does not stem from power lines or mobile phone networks", Mouritsen stresses, explaining that electromagnetic interference within the two kilohertz to five megahertz frequency range is mainly generated by electronic devices. "The effects of these weak electromagnetic fields are remarkable: they disrupt the functioning of an entire sensory system in a healthy higher vertebrate."
It all started with a stroke of luck. For around 50 years it has been known that migratory birds use the Earth's magnetic field to determine their migratory direction. Biologists have proven this in numerous experiments in which they tested the birds' navigation abilities in so-called orientation cages. "So we were surprised when robins kept in wooden huts on the Oldenburg University campus were unable to use their magnetic compass", Mouritsen recounts.
Dr. Nils-Lasse Schneider, an electrophysiologist and researcher in Mouritsen's work group, then came up with the idea that set things in motion: he proposed covering the wooden huts, along with the orientation cages they contained, with sheets of aluminium. This did not affect the Earth's magnetic field, which is vital for the birds to navigate, but it strongly attenuated the time-dependent electromagnetic interference – the electrosmog – inside the huts.
The effect was astounding: suddenly the birds' orientation problems disappeared. "Our measurements of the interferences indicated that we had accidentally discovered a biological system that is sensitive to anthropogenic electromagnetic noise generated by humans in the frequency range up to five megahertz", Mouritsen says. The surprising thing here, the biologist adds, was that the intensity of the interference was far below the limits defined by the International Commission on Non-Ionizing Radiation Protection and the WHO.
Considering the potential importance of the finding, Mouritsen and his team performed a large number of experiments to provide evidence of the effect they observed: “Over the course of seven years we carried out numerous experiments and collected reliable evidence, in order to be absolutely certain that the effect actually exists.” Under the leadership of Svenja Engels, Mourtisen's doctorate students conducted numerous so-called double-blind studies. Several generations of students repeated the experiments independently of one another on the Oldenburg campus. What they found was that as soon the grounding of the screens was disconnected or electromagnetic broadband interference was deliberately created inside the aluminium-clad and earthed wooden huts, the birds' magnetic orientation ability was immediately lost again.
Furthermore, the scientists were able to show that the disruptive effects were generated by electromagnetic fields that cover a much broader frequency range at a much lower intensity than previous studies had suggested. This electromagnetic broadband interference is omnipresent in urban environments. It is created wherever people use electronic devices. As expected, it is significantly weaker in rural areas. And indeed, unlike on the University campus, the magnetic compass of the robin did function in orientation cages placed one to two kilometres outside city limits, even without any screening. “Thus, the effect of anthropogenic electromagnetic noise on bird migration is localised. However these findings should make us think – both about the survival of migratory birds as well as about the potential effects for human beings, which have yet to be investigated”, Mouritsen concludes.
Prof. Dr. Henrik Mouritsen has been teaching and conducting research at the University of Oldenburg since 2002, and obtained his habilitation there in 2005. The Danish biologist has held a Lichtenberg Professorship from the VolkswagenStiftung since 2007. Through its “Lichtenberg Professorships” initiative the foundation funds outstanding scientists in innovative fields of teaching and research. Mouritsen researches the behavioural, molecular, physiological and cognitive mechanisms underlying long-distance navigational abilities in migratory birds. As head of the international research group “Neurosensorik/Animal Navigation” he has contributed substantially to the current state of the art suggesting that the birds use the Earth's magnetic field for orientation in two different ways. Light-sensitive molecules in their eyes enable them to visually detect the compass direction of the magnetic field. Furthermore, the birds seem to have magnetic sensors associated with the ophthalmic branch of the trigeminal nerve, which are connected via neural pathways to the brainstem. Mouritsen's group identified for the first time the areas in the birds' brains involved in both these orientation systems.
“Anthropogenic electromagnetic noise disrupts magnetic compass orientation in a migratory bird” by Svenja Engels, Nils-Lasse Schneider, Nele Lefeldt, Christine Maira Hein, Manuela Zapka, Andreas Michalik, Dana Elbers, Achim Kittel, P.J. Hore, Henrik Mouritsen, Nature.
Dr. Corinna Dahm-Brey | idw - Informationsdienst Wissenschaft
Study suggests new way of preventing diabetes-associated blindness
26.05.2015 | Johns Hopkins Medicine
Memories Influence Choice of Food
22.05.2015 | Universität Basel
Many joining and cutting processes are possible only with lasers. New technologies make it possible to manufacture metal components with hollow structures that are significantly lighter and yet just as stable as solid components. In addition, lasers can be used to combine various lightweight construction materials and steels with each other. The Fraunhofer Institute for Laser Technology ILT in Aachen is presenting a range of such solutions at the LASER World of Photonics trade fair from June 22 to 25, 2015 in Munich, Germany, (Hall A3, Stand 121).
Lightweight construction materials are popular: aluminum is used in the bodywork of cars, for example, and aircraft fuselages already consist in large part of...
Using ultrashort laser pulses, scientists in Max Planck Institute of Quantum Optics have demonstrated the emission of extreme ultraviolet radiation from thin dielectric films and have investigated the underlying mechanisms.
In 1961, only shortly after the invention of the first laser, scientists exposed silicon dioxide crystals (also known as quartz) to an intense ruby laser to...
The only professorship in Germany to date, one master's programme, one laboratory with worldwide unique equipment and the corresponding research results: The University of Würzburg is leading in the field of biofabrication.
Paul Dalton is presently the only professor of biofabrication in Germany. About a year ago, the Australian researcher relocated to the Würzburg department for...
Physicists have developed an innovative method that could enable the efficient use of nanocomponents in electronic circuits. To achieve this, they have developed a layout in which a nanocomponent is connected to two electrical conductors, which uncouple the electrical signal in a highly efficient manner. The scientists at the Department of Physics and the Swiss Nanoscience Institute at the University of Basel have published their results in the scientific journal “Nature Communications” together with their colleagues from ETH Zurich.
Electronic components are becoming smaller and smaller. Components measuring just a few nanometers – the size of around ten atoms – are already being produced...
Development and implementation of an advanced automobile parking navigation platform for parking services
To fulfill the requirements of the industry, PolyU researchers developed the Advanced Automobile Parking Navigation Platform, which includes smart devices,...
20.05.2015 | Event News
18.05.2015 | Event News
12.05.2015 | Event News
29.05.2015 | Life Sciences
29.05.2015 | Earth Sciences
29.05.2015 | Physics and Astronomy