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Wednesday, 18 September 2019
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Raw materials & technologies, Technologies, Nanotechnology

Facade paints: There is no risk of nano-dust danger

Monday, 20 January 2014

After 42 months the research project "NanoHouse” has ended, and the verdict is a cautious "all clear” – nanoparticles in the paint used on building facades do not represent a particular health risk.

According to latest research, nanoparticles in the paint used on building facades do not represent a particular health risk

Source: Kalle Kolodziej - Fotolia.com
According to latest research, nanoparticles in the paint used on building facades do not represent a particular health risk Source: Kalle Kolodzie...

In the course of a "Technology Briefing” Emparesearchers discussed the results with specialists from the construction industry. The institute has been, and continues to be, involved in several EU research projects and has also contributed to various information brochures on the subject of nanomaterials. One outcome of this effort is the website Nanopartikel.

Research into the safety of nanoparticles

The "NanoHouse” project, which is financially supported through the EU, began in 2010 with the aim of investigating possible health effects caused by nanoparticles in building materials and houses. Various aspects of the research program included rubbing tests on model facades, attempts to wash out nanoparticles from surface coatings and an analysis of the biological effects on humans and the environment. For the first time not only were freshly manufactured products studied to see if they set free nanoparticles, but also aged samples.

Many laboratory studies but only a few products

Some paints containing silicon dioxide are water repellent, easy to clean and scratch resistant. Nano titanium-dioxide has photocatalytic properties and can decompose air pollutants. Nano titanium-dioxide, along with nano zinc-oxide and nano-iron oxide, can be used to provide UV protection and, depending on the size of the particles used, also to protect against infrared radiation, i.e. heat. Similarly, nanoparticles can protect against attack by blue stain fungus and algae. Whilst many laboratory studies have confirmed the effectiveness of nanoparticles, in practice one question remains open: how much of the nanomaterial does one have to mix with the paint to ensure that it functions as expected? For this reason only a few products for external façades containing nano-materials are available on the market to date. The greatest opportunity nanoparticles offer lies in the combination of various functional properties, for example scratch resistance and easy (or self) cleaning characteristics.

Astonishingly little is released to the environment

The results of the investigations into how much nanomaterial is set free from facades showed: The release rate is generally very low – only 1 to 2% of the nanoparticles find their way into the environment. And in most cases they are released not as nanoparticles but bound to large paint particles, which significantly reduces their nano-scale effects. The researchers had expected that the catalytically active nanoparticles would also attack the paint surrounding them, leading to more frequent release. Toxicological studies revealed that paints containing nanoparticles have the same effect on the behaviour of cells from the gastrointestinal tract and immune system as do similar paints which do not contain nanoparticles. The researchers don’t therefore expect that these nanoparticle-containing paints will represent a new, acute health risk. However, the investigations did at the same time show that nanoparticles are absorbed by the cells. Whether this accumulation of nanoparticles in the cells might lead to longer-term effects cannot yet be definitively determined.

Making a plea for a reasonable balance

For a house with an assumed lifetime of eighty years, painting the facade with nanomaterial based paint would be more economic if this lasted for 30% longer than conventional coatings. Then, over the lifetime of the house, one would have to repaint the façade one time fewer, avoiding all the environmental effects caused by manufacturing the paint and disposing of the leftover material. This theory remains somewhat controversial however – houses are frequently repainted for aesthetic reasons and not because a new coating is strictly necessary. In this case the advantage offered by the longer lifetime of nanoparticle-based coatings becomes completely irrelevant.

Lack of awareness in industry

A risk researcher reported on the results of an industrial survey. Many companies expected paint containing nanoparticles to have a longer lifetime than conventional paint. Some expected it to be easy to handle, for example because it dries faster. But exactly how one correctly disposes of leftover paint containing nanoparticles is something that only a handful of respondents knew. The Painter’s and Plasterer's Association gave the view from the sharp end, where quite simply the customer is king, and sometimes demands the latest in paint technology. On the other hand, about half of all painters are female, so protection from possibly unhealthy chemicals is therefore particularly important. The association needs more information, so that it can take up a clear position with respect to customers and employees.

Nanomaterials should not have a negative affect on recycling

Finally, the Swiss Federal Office of the Environment (SFOE) explained the current regulations covering the disposal of waste material containing nanoparticles. On its website the SFOE offers tips on how to dispose of such material properly. The current regulations relating to safe working practices with nanomaterials were explained by the Swiss government’s State Secretariat for Economic Affairs (SECO). The essential point here is that the manufacturer of the material must provide a Material Safety Data Sheet, as is the case with other chemicals.

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