Brakes pollute waters

Heavy metal contamination due to tire wear higher than due to exhaust gases

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Whoever talks about environmental pollution by cars usually means the exhaust fumes. Surprisingly, the greatest heavy metal contamination for watercourses is caused by the abrasion of brake linings and tires. According to a new study, road traffic has replaced industry as the largest heavy metal polluter. At more than half of the measuring points in German waters, the limit values ​​for copper and zinc have now been exceeded with consequences for sensitive animal and plant species.


The vehicles are still a source for other pollutants, according to the study of the Fraunhofer Institute for Systems and Innovation Research (ISI) in Karlsruhe: Every year, 932 tons of copper, 2, 078 tons of zinc and carbon come through the abrasion of brake linings and tires 80 tons of lead in the environment. The equipment of roads and highways with galvanized guard rails or gantries as well as the road wear also contribute to the burden.

Sewer transports contaminated water

However, road traffic does not bear sole responsibility for this, as the investigations on behalf of the Federal Environmental Agency show. On roofs and facades of buildings, these metals are also increasingly used because of the longer durability, for example of gutters, and because of the ease of processing. However, due to design considerations, architects today also like to use copper and zinc veneers, with the result that every year 85 tonnes of copper, 682 tonnes of zinc and 25 tonnes of lead are released into the environment, the lion's share of them through sewers into rivers and lakes.

"There are sensible alternatives, " says Thomas Hillenbrand, project manager at the Fraunhofer ISI. These find builders and architects in a guide of the Federal Environment Agency. In addition to refraining from large metal surfaces on buildings, the guide lists other metallic products such as tinned copper sheet, coated zinc sheet or aluminum and stainless steel sheets, which have significantly lower corrosion rates. Filter systems for treating roof runoff water also help to reduce heavy metal pollution. display

Hillenbrand sees an urgent need for action with brake pads. Although it has not been possible to produce brake linings containing lead since 2004, lead balancing weights are also banned, but copper is still contained in brake linings, although that would no longer be necessary. There are already copper-free coverings in the spare parts trade, but these have not yet been implemented as original equipment by car manufacturers.


The study "Entries of copper, zinc and lead in waters and soils - Analysis of emission paths and possible emission reduction measures" can be downloaded here.

(Fraunhofer Institute for Systems and Innovation Research, 16.02.2007 - AHE)