Russ is dangerous

What makes soot particles so dangerous?


When researchers use solvents to separate soot particles from the chemical toxins attached to them, the following becomes apparent: Bare soot particles trigger a genetic detoxification mechanism in cell cultures. But the washed-out substances that previously stuck to the soot also have their effect: They cause inflammatory reactions in the cells and also act as cell toxins.

Particulate matter
Fine dust is considered toxic and, according to estimates by the EU Commission, costs many Europeans their lives every year. With a size of less than 10 µm fine dusts can float in the air (so-called airborne dusts) and can be inhaled by humans, so that the fine dust particles can get into the lungs and pass into the body via the alveoli. So they advance into the liver, among other things.
is dangerous to health - this knowledge is not new. But what makes particulate matter so dangerous? Is it just the diesel soot from the engines or is the danger, e.g., from the wood-burning fireplace in the holiday home? Or even from the fat-smoking deep fryer smoke from the restaurant next door? For a long time, such questions were a tough nut to crack for science. Sooty fine dust could be collected in filters in order to analyze the chemical components. Nevertheless, the question remained: where exactly is the danger? Is it the soot particles themselves that make people sick? Or is it toxins that the soot carries around with it - like a soaked sponge?

Artur Braun, physicist at the Eidgenössische Materialprüfungs- und Forschungsanstalt (Empa) and an expert in X-ray spectroscopy, has made a significant contribution to analyzing the structure and composition of soot particles. Before joining Empa, the researcher had worked at the University of Kentucky and there in 2002 for the first time soot particles with the help of soft X-rays on a synchrotron synchrotron
Particle accelerator in which charged elementary particles or ions can be accelerated to very high (relativistic) speeds so that they receive a particularly high kinetic energy.
analyzed. The result: Diesel particles that are created in the engine under high pressure and heat have a graphite framework - this can be clearly seen in X-ray light. In the case of soot particles from wood fires, which were created under mild atmospheric conditions, this graphite framework is missing. The chemical functional groups also differed: in diesel soot, there were carboxyl groups as they also occur on formic acid and acetic acid molecules; Braun found hydroxyl groups in wood smoke, as is known from methanol and ethanol. So not all smoke is the same.

Toxicologists from the Norwegian Ministry of Health (Norwegian Institute of Public Health) now went a step further and with the help of solvents, the soot particles were removed from the chemical toxins at Braun's colleagues at the University of North Dakota separate. Braun then analyzed the components individually using X-ray light: first the bare soot particles, then the solution with the allegedly carcinogenic toxins that had previously adhered to the soot. Braun again found various functional groups on the carbon skeleton and was able to compare them with the findings of his earlier research.

At the same time, the toxicologists tested what effect the two fractions of soot particles have on human lung cell cultures. For the first time, it was examined separately what is so dangerous about soot. According to von Braun, the study, which recently appeared in the journal Toxicology Letters (online publication on November 9, 2011) is the first in which the X-ray absorption spectroscopy (NEXAFS) method was combined with toxicological research methods.

The result of the study was clear: the bare soot particles triggered a genetic detoxification mechanism in cell cultures. So the cells had been attacked. But the washed-out substances that had previously adhered to the soot also had an effect: They caused inflammatory reactions in the cells and also acted as cell toxins.

The World Health Organization responded at the same time. Several new studies - including those by Braun and his colleagues from Norway and the USA - had indicated the carcinogenic effects of soot and adequately explained the mechanisms. Now it could no longer - as since 1988 - from the probable risk of cancer ("probably carcinogenic to humans“) Can be spoken. The new classification followed on June 12, 2012 - see also Diesel soot is now proven to be ("based on sufficient evidence“) Lung cancer causing. There is also a certain probability that diesel soot also increases the risk of bladder cancer.

Another publication on the subject of fine dust from wood combustion is currently in preparation, to which Braun has also made decisive contributions. The cooperation between the disciplines will not end there. "The medical-scientific potential of synchrotron methods for analyzing the biological interaction of cells with pathogenic substances is far from being exhausted," says Braun.

Source: Empa - Federal Materials Testing and Research Institute