"Nano particles are penetrating the brain

Synthetic nano particle can penetrate tissue and cells and spread all over the body - even into the brain. Professor Peter Gehr of the university of Bern - an international prestigious specialist on tissues - is astonished about the fact that outside of science and public administration almost noone acknowledge the possible health riscs.

Internview: Kaspar Meuli

Does the Swiss population is taking care about the health impacts of nano particles?

Peter Gehr: No, because either people don't have any idea what it is all about or they don't look at it as a problem. Also the possible dangers are not a topic in politics.

Why this carelessness?

Peter Gehr: The nano technology and the with corresponding procedures produced nano particles are intriguing and have already accomplished positive applications like for example advanced materials. That way it is possible to produce very tough and extremely light materials with nanotubes out of carbon. With that material a bicycle frame is a couple of kilogram less heavier.

On the other side there are alarming news - for example about chinese female workers, who shall suffer with lung afflictions because of high concentrations of nano particles at the working place.

Meanwhile it has been shown that the corresponding study had severe defects. As the media captured this topic in December 2009, I thought however now the mood would tip. I assumed that we nano researchers had to justify ourselves because people bother seriously. But the newspaper news did not trigger any greater debate, and the topic was frizzled out within days. People are not even reacting at the moment to the at best dubious sides of artificial nano particles.

Have you as a researcher restrained your concerns too strongly?

Peter Gehr: No, on the contrary. I explain where the dangers are everywhere - in talks with female and male politicians, at public lectures and on panel discussions: If nano particles are not bounded tightly to some material there is a risc to inhale them. Then they can get into the lungs and spread into the whole body. Still we don't know what kind of implications this will have for the health. But the fact alone is problematic that particles penetrate into our body. However, outside of science and public administration it is hardly taking note of this.

Laypersons are obviously irritated about the contradictory judgment about the chances and riscs of that technology.

Peter Gehr: I have also been strongly irritated for about a year. In animal experiments there is proof that nano particles penetrate tissue and cells and can spread through the blood all over the body - even into the brain. Admittedly we still don't know how this exactly is taken place. Since recently it is talked about amongst researchers that nano particles which get into contact with our organism will be covered with a layer of proteins. This is happening at the latest if they get on to the surface film which covers the inner lung surface. We still know little about this so called "Coating" of the particles. Thus it is vague how exactly this is working, if the protein coat in the way of penetration into the cells is being changed and what kind of meaning this has to the functioning of the cells. For my part this is the greatest insecurity regarding the health riscs in contact with nano particles.

What are you saying to studies which immediately suggest themselves that nano tubes out of carbon are as dangerous as asbestos?

Peter Gehr: From filaments of asbestos it is known that they can lead to cancerous changes at the outer lung surface. Now there were animal experiments with synthetic nano tubes which are structured in their dimensions similiar to the filaments of asbestos. During experiments into the abdominal cavity of mice the implemented particles were entitled to lumplike enlargements which are held to be predecessors to cancer. Whereas nano tubes which were not comparable to shape and size with filaments of asbestos did not cause such changes.

Is this result comforting or does exist cause of concern?

Peter Gehr: I have fundamental objections towards nano tubes out of carbon - namely independently from their shape. The imagination to have to inhale nano- or micrometersized tubes causes me to be frightened. We are not that far away from such scenarious.

At a congress for nano technology in Japan recently there were introduced tires which shall give them a higher resistivity with nano tubes out of carbon. Presumed, all cars on the road had such tires, we would have a real problem indeed. The rubber and the therein enclosed nano particles would be rubbed, effloresced and the nanotube out of carbon would be released into the air. This imagination is not that unrealistic.

Our breathing air is already today strained with fine dust. Do these particles operate to our health in a different way than nano particles industrially produced?

Peter Gehr: No, because the main problem during the penetration of solid particles into our organism is their seize. The seize is much more important than the shape or the kind of the material from what they were being produced of - how we could certify at our institute. So called PM10-particles which contain many nano particles are underlying the same physical mechanism. They get bathed and afterwards shifted into the depth towards the lung tissue.

Is fine dust in this way equally as dangerous as artificial nano particles?

Peter Gehr: This is practically the same.

How problematic is the proof of nano particles in the brain?

Peter Gehr: We could show with the most modern microscopes in my laboratory that nano particles break down the air-blood-barrier. Analogly to this they can get also through the blood-brain-barrier into the brain tissue, which has been proven by research colleagues in animal experiments with the aid of radioactive substances. Admittedly it is a matter of tiny amounts but that is still thousands upon thousands of nano particles which penetrate into the brain by that way.

Could this lead to impairment?

Peter Gehr: I know the work of a female colleague who grew up in Mexico City and then has worked in the leading centers of environmental research in the USA. She has examined brains of men who died from Alzheimer. She compared these with the brain tissue of a young male who lived his whole life at a very car-used street in Mexico City and then lost his life through an accident. I will never forget the intriguing parallels of these brain pictures. The same inflammatory changes of the brain manifested in both cases - so called beta-amyloid plaques -, which are being categorized as antecedent of Alzheimer. Very exaggerated, we may conclude from this context that air pollution leads to Alzheimer.

Is this certain?

Peter Gehr: No, at the moment these are hypotheses. But various researchers are arising the question: if environmental pollution could not be one cause of Alzheimer. If this was the case then with the greatest probability by the way of inhalation of particles which got into the blood and surpassed the blood-brain-barrier.

Contact: magazin@bafu.admin.ch
Bundesamt für Umwelt BAFU
(Federal agency for the environment)"
Translation by Denglisch
http://www.bafu.admin.ch/dokumentation/umwelt/10649/10659/index.html?lang=de