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RESEARCHERS PROVE THAT NOT ONLY QUANTITY OF DUST PARTICLES LUNGS BUT ALSO AMOUNT OF METAL
International organizations like the WHO point to the quantity of aerosol pollutants in the air we breathe as the greatest health problem related to air quality. Even most filter systems are unable to hold back the finest dust particles emitted by industrial plants and road vehicles. These microscopic particles, measuring less than 2.5 micrometers across, often contain metals that pose a health risk. But current environmental emission standards only prescribe limits for the concentration of particles, or total mass per volume of air. A recent study of particulate air pollution in Hettstedt, south of the city of Magdeburg, indicates that such values are inadequate for the purpose of establishing recommendations on the basis of sound toxicological data. This small industrial town has a long tradition of mining and metalworking, especially copper. It suffered from severe air pollution until the 1990s, since when an industrial modernization program has succeeded in reducing the level of particulate emissions to that of surrounding rural areas. And yet children living in Hettstedt are still significantly more likely to suffer from asthma than those only fifty kilometers away in the rural town of Zerbst. In order to establish reasons for this disparity, researchers at the Fraunhofer Institute of Toxicology and Experimental Medicine ITEM got together with colleagues at the National Research Center for Environment and Health near Munich to examine the effect of metal-contaminated environmental aerosols (Am. J. Respir. Crit. Care Med. 2004, vol. 170, p. 898). The medical researchers conducted tests that involved depositing samples of dust taken from each of the two locations in separate areas of the lungs of twelve healthy volunteers. The applied dose of 100 micrograms corresponds to the quantity normally inhaled by a human subject over 24 hours. The team at the ITEM department of clinical allergy, asthma and inhalation research found that the metallic dust samples from Hettstedt provoked a significantly more pronounced inflammatory response than the samples from Zerbst. "It's not just the quantity of dust that counts, but also its quality, for instance metal content," sums up head of department, Professor Norbert Krug. "Importantly, we were the first in Germany to carry out clinical tests directly in the human lung, and to provide evidence of an inflammatory response to such a low volume of particles, which is representative of the real environmental burden." These findings are sure to spark off a new debate on the limits for particulate emissions prescribed in the EU.
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