13-May-2016 - Empa (Eidgenössische Materialprüfungs- und Forschungsanstalt)

How nanoparticles flow through the environment

Carbon nanotubes remain attached to materials for years while titanium dioxide and nanozinc are rapidly washed out of cosmetics and accumulate in the ground. Researchers from the National Research Programme "Opportunities and Risks of Nanomaterials" (NRP 64) have developed a new model to track the flow of the most important nanomaterials in the environment.

How many man-made nanoparticles make their way into the air, earth or water? In order to assess these amounts, a group of researchers led by Bernd Nowack from Empa in St. Gallen has developed a computer model as part of the National Research Programme "Opportunities and Risks of Nanomaterials" (NRP 64).(*) “Our estimates offer the best available data at present about the environmental accumulation of nanosilver, nanozinc, nano-tinanium dioxide and carbon nanotubes”, says Nowack.

Cosmetics and tennis racquets

In contrast to the static calculations hitherto in use, their new, dynamic model does not just take into account the significant growth in the production and use of nanomaterials, but also makes provision for the fact that different nanomaterials are used in different applications. For example, nanozinc and nano-titanium dioxide are found primarily in cosmetics. Roughly half of these nanoparticles find their way into our waste water within the space of a year, and from there they enter into sewage sludge. Carbon nanotubes, however, are integrated into composite materials and are bound in products such as which are immobilized and are thus found for example in tennis racquets and bicycle frames. It can take over ten years before they are released, when these products end up in waste incineration or are recycled.

39,000 metric tons of nanoparticles

The researchers involved in this study come from Empa, ETH and the University of Zurich. They use an estimated annual production of nano-titanium dioxide across Europe of 39,000 metric tons – considerably more than the total for all other nanomaterials. Their model calculates how much of this enters the atmosphere, surface waters, sediments and the earth, and accumulates there. In the EU, the use of sewage sludge as fertiliser (a practice forbidden in Switzerland) means that nano-titanium dioxide today reaches an average concentration of 61 micrograms per kilo in the affected ground.

Knowing the degree of accumulation in the environment is only the first step in the risk assessment of nanomaterials, however. Now this data has to be compared with ecotoxicological test results and the statutory thresholds, says Nowack. A risk assessment has not been carried out with his new model until now. Earlier work with data from a static model showed, however, that the concentrations determined for all four nanomaterials investigated is not expected to have any impact on the environment.(**)

But in the case of nanozinc at least, its concentration in the environment is approaching the critical level. This is why this particular nanomaterial has to be given priority in future ecotoxicological studies – even though nanozinc is produced in smaller quantities than nano-titanium dioxide. Furthermore, ecotoxicological tests have until now been carried out primarily with freshwater organisms. The researchers conclude that complementary investigations using soil-dwelling organisms is a priority.

Facts, background information, dossiers
More about Empa
  • News

    Visualizing chemical reactions

    Researchers at the joint EPFL-Empa lab in Sion have developed a reactor system and an analysis method that has allowed them to observe the real-time production of synthetic natural gas from CO2 and H2 for the first time. Infrared (IR) thermography is used to determine the temperature of hu ... more

    How to induce magnetism in graphene

    Graphene, a two-dimensional structure made of carbon, is a material with excellent mechani-cal, electronic and optical properties. However, it did not seem suitable for magnetic applica-tions. Together with international partners, Empa researchers have now succeeded in synthesiz-ing a uniqu ... more

    First field measurements of laughing gas isotopes

    Thanks to a newly developed laser spectrometer, Empa researchers can for the first time show which processes in grassland lead to nitrous oxide emissions. The aim is to reduce emissions of this potent greenhouse gas by gaining a better understanding of the processes taking place in the soil ... more

  • Videos

    A water-based, rechargeable battery

    First step to produce a cheap aquous electrolyte for powerful rechargeable batteries: Seven grams of sodium FSI (precise name: sodium bis(fluorosulfonyl)imide) and one gram of water produce a clear saline solution with an electrochemical stability of up to 2.6 volts – twice as much as other ... more

More about ETH Zürich
  • News

    Underestimated chemical diversity

    An international team of researchers has conducted a global review of all registered industrial chemicals: some 350,000 different substances are produced and traded around the world – well in excess of the 100,000 reached in previous estimates. For about a third of these substances, there i ... more

    A fast light detector made of two-dimensional materials

    Two research groups at ETH Zurich have joined forces to develop a novel light detector. It consists of two-​dimensional layers of different materials that are coupled to a silicon optical waveguide. In the future, this approach can also be used to make LEDs and optical modulators. Fast and ... more

    Platelets instead of spheres make screens more economical

    ETH scientists have further developed QLED technology for screens. They have produced light sources that for the first time emit high-​intensity light in only one direction. This reduces scattering losses, which makes the technology extremely energy efficient. QLED screens have been on the ... more

  • Videos

    Oxybromination of methane over vanadium phosphate

    ETH Zurich scientists have discovered a new catalyst that allows the easy conversion of natural gas constituents into precursors for the production of fuels or complex chemicals, such as polymers or pharmaceuticals. The new catalyst is extremely stable and results in fewer unwanted by-produ ... more

More about Universität Zürich
  • News

    Trust in Science and Research Remains High

    The Swiss population’s trust in science and research is high to very high. As the Science Barometer Switzerland 2019 study shows, people in Switzerland have a positive attitude towards science and are keen to receive information about research, with climate and energy considered the most im ... more

    Recycling carbon dioxide from the ocean

    Paper, tin cans, glass - the world recycles as much as possible. So why not declare the greenhouse gas carbon dioxide (CO2) a recycling product as well? Liquid fuels based on carbon will continue to play an important role in the future - despite international efforts to reduce them. So it s ... more

    Researchers Observe Slowest Atom Decay Ever Measured

    The XENON1T detector is mainly used to detect dark matter particles deep underground. But a research team led by Zurich physicists, among others, has now managed to observe an extremely rare process using the detector – the decay of the Xenon-124 atom, which has an enormously long half-life ... more

More about Schweizerischer Nationalfonds zur Förderung der wissenschaftlichen Forschung
  • News

    Diamond watch components

    SNSF-funded researchers have developed a new technique for carving materials to create micromechanical systems. In particular, they have created a miniscule watch component out of synthetic single-crystal diamond. Diamond is very hard and elastic, a very good thermal conductor and highly tr ... more

    The first precise measurement of a single molecule's effective charge

    For the first time, scientists have precisely measured the effective electrical charge of a single molecule in solution. This fundamental insight of an SNSF Professor could also pave the way for future medical diagnostics. Electrical charge is one of the key properties that allows molecule ... more

    The key to chemical transformations

    Chemist Xile Hu is the winner of the National Latsis Prize for 2017. Hu, a professor at the École Polytechnique Fédérale de Lausanne, was recognised for his outstanding scientific career and his original contributions to the fundamental understanding of catalysis. Catalysis is a field of ch ... more

  • Videos

    The key to chemical transformations

    Chemist Xile Hu is awarded the National Latsis Prize 2017, Xile Hu is Professor of Chemistry at the Swiss Federal Institute of Technology in Lausanne (EPFL). He is honored for his impressive scientific career and outstanding research on the fundamental understanding of catalysis. more