Fine dust acts up to the brain

Far-reaching consequences of particulate matter pollution

09/06/2014

Numerous studies have already investigated possible health effects caused by high particulate matter pollution in the past. Last had that „British Medical Journal“ published a study that concluded that increased particulate matter exposure in the long term is associated with a significantly increased risk of acute cardiovascular disease (unstable angina pectoris, myocardial infarction).

However, all studies have the weakness that they either test the effect of particulate matter under laboratory conditions, but in reality do not do justice to the cumulative exposure from different sources in reality. Or they observe the occurrence of cardiovascular diseases in certain places at certain pressures, but they can not differentiate sufficiently between the different factors. Here, a complex overlap of all available studies is required to enable a reliable assessment of the health risks of particulate matter.

Fine dust as a cause of numerous diseases in the discussion
Among epidemiologists, there is widespread agreement that high concentrations of particulate matter are a major risk factor for cardiovascular disease and respiratory distress. However, particulate matter is also discussed as a possible risk factor for numerous other diseases, such as Parkinson's or Alzheimer's. For example, a study by the Institute of Epidemiology I at the Helmholtz Zentrum München has shown, „that there was a higher insulin resistance in those children who were more exposed to particulate matter.“ Fine dust up to a diameter of 10 microns (µm) in the air „to an increase in insulin resistance by 19 percent per 6 µg / m⊃3;“ guided. Professor Holger Schulz, deputy director of the Institute of Epidemiology I at the Helmholtz Center, told „World Online“, There is also evidence that particulate matter promotes a reduced birth weight of babies and could be responsible for kidney disease and diabetes. „These are not huge effects, but a large part of the population is affected“, cited „World Online“ the physiology professor.

Regular exceedance of EU limit values
The actual particulate matter pollution is recorded in cities with so-called environmental monitoring stations. Despite the efforts to reduce the fine dust concentration, these often show clear violations of the permissible EU limit values. So reported „World Online“ citing the figures of the Baden-Württemberg state institute for environment, measurements and nature protection, that for example the measuring station at the Stuttgart Neckartor for the coarser fine dust „PM10“ (Particle size between 2.5 and 10 µm diameter) on 51 of 120 days had exceeded the EU limit. However, a maximum of 35 exceedances per year are tolerable under the Air Quality Directive. The station regularly takes the sad nationwide top spot in the fine dust concentration with the measured values. The consequences of these burdens for local residents are difficult to predict. Currently, physicians around the world are still busy drawing an overall picture of the health risks associated with particulate matter from the study results available „World Online“. Apart from the information gained from laboratory experiments and the results of clinical studies, the statistics of the epidemiologists are of particular importance here. „You have to bring it all together to get an overall picture“, stressed Professor Schulz.

Causal connection in cardiovascular diseases
In the epidemiology, statistical correlations between the fine dust concentrations and occurring diseases are determined, which, according to Prof. Annette Peters, director of the Helmholtz Institute for Epidemiology II in Munich, a realistic and reliable statement on health risks through increased particulate matter pollution. Therefore, I'll „put more and more emphasis on epidemiological studies“, cited „World Online“ the expert. Although only correlations (correlations) are shown in the epidemiological studies at first, they do not have to be of a causal nature. But from the large number of studies, causal relationships can generally be identified relatively reliably. In particular with regard to cardiovascular diseases, this is the case with fine dust, for example. Prof. Peters explained that, together with colleagues in 2010, she analyzed the causal evidence for the relationship between particulate matter and cardiovascular morbidity and mortality for the American Heart Association, with the result, „that this relationship is probably causal.“

Reactions throughout the organism
In addition, there are the results from the laboratory studies, in which the reactions were observed in the organism on the fine dust. Professor Schulz explained that the particulate matter „a local response in the lungs and a systemic response that covers the whole organism“, causes. It is known from animal experiments that the particles stimulate certain receptors, which in turn alter the balance in the autonomic nervous system. The effect is best seen in the heart, „because you measure changes in the heart rate and also in the regularity of the heartbeat“, cited „World Online“ the physiologist. Furthermore, the immune system tries to eliminate the foreign bodies in the lungs and react with a corresponding inflammation, which also has a systemic effect. The coagulability of the blood is increased, the regulation of the vessel size is influenced and the blood pressure rises. Schulz also sees in the impairment of the blood circulation a possible explanation for the established relationship between particulate matter pollution and reduced birth weight in infants. „As the circulation through the placenta is regulated down, it provides the child with fewer nutrients“, so the presumption of the physiologist. However, this remains a hypothesis so far.

Immune response to the particulate matter
The systemic effect of the particulate matter also contributes to the immune response to penetrating nanoparticles in the various affected organs. For example, would „to find changes directly in the heart, „the direction of inflammation, activation of the immune cascade go“, explained Prof. Schulz. In his estimation, the immune response of the mechanism underlies all the proven fine dust effects in the animal experiments. Thus, it is also the trigger of increased liver activity and even neurodegenerative phenomena could be due to nanoparticles that have crossed the blood-brain barrier, said Schulz. In addition, an immigration via the olfactory cells of the nose, which form a direct extension of the brain, is possible. It has long been known that nanoparticles can enter the brain in this way. Even the most recent association with diabetes and kidney disease found in animal experiments may be explained by the inflammatory mechanisms.

Measures to reduce particulate matter pollution
Although particulate matter is regarded as a risk factor for many illnesses, it is hardly possible to precisely allocate individual diseases in practice. According to Prof. Schulz, the concrete effect of particulate matter can only be estimated from a theoretical human being who has no other risk factors. To determine particulate matter as the cause of the disease with existing symptoms, therefore, remains excluded, even if there appears to be clear evidence for individual diseases. Measures to further reduce particulate matter in cities are, however, justified in any case, given the information available. For example, the introduction of environmental zones has proven to be a relatively reliable, cost-effective means here. They are called for the inner cities or particularly traffic-heavy areas and allow only vehicles with a plaque the driveway. The sticker certifies that a certain pollutant emissions is not exceeded. As traffic dust accounts for the largest proportion of pollution in cities, well-developed local public transport, for example, is certainly suitable as a measure to reduce particulate matter pollution. In particular, municipalities are called to act with regular exceedances of the EU limit values ​​in the interests of the health of their inhabitants. (Fp)

Picture: gnubier