Nanoparticles in cosmetics can stick together, study finds.

Jun 27, 2012

Nazarenko Y, H Zhen, T Han, PJ Lioy and G Mainelis. 2012. Potential for inhalation exposure to engineered nanoparticles from nanotechnology-based cosmetic powders. Environmental Health Perspectives http://dx.doi.org/10.1289/ehp.1104350.

Synopsis by Cheryl Stein

Microscopic particles in makeup and other cosmetics can clump together and lodge in nasal passages, according to a new study. This suggests that nanoparticles in cosmetics should be tested to ensure their safety.

Nanoparticles in powder blush and other make-up can clump and form larger particles when applied to the face, reports a laboratory study in the journal Environmental Health Perspectives.

These bigger particles are more apt to stick in the upper airways rather than travel into the lungs as single particles would. It is not clear whether this exposure to the aggregated particles poses health risks.

The findings, though, suggest more research is needed to find out if exposure to nanoparticles in consumer products is harmful. Right now, no safety tests specifically for nanoparticles are required. Studies like this are important because they point out the factors – such as particle size and aggregation – to consider when safety tests for nanomaterials are adopted.

Nanoparticles are tiny. Most are about the size of human proteins or a DNA molecule. About 10,000 nanoparticles could fit across the width of a single strand of human hair.

Manufacturers are interested in using nanoparticles because they behave differently from larger ones of the same materials. Some of these different properties are valuable because they can enhance and improve products.

For instance, remember the thick, white sunscreen that could never be rubbed completely into skin? The pasty cream was made from two chemicals – titanium and zinc – used to protect skin from the sun’s ultraviolet rays. Now, some use titanium and zinc nanoparticles, and the result is clear, easily absorbed sunscreens.

These improved consumer products may not come without a price. Past studies show nanoparticles in cosmetics can be absorbed through the skin or breathed in through the nose and mouth. Once in the airways, particle size may determine where they end up. Generally, the smallest can go deep into the gas exchange area of the lung, larger aggregated ones in the windpipe or bronchial tubes, and the even larger agglomerates in the head via the nose.

To better understand how nanomaterials act, researchers applied makeup to a specially designed mannequin head with a fake nose. According to a manufacturers inventory list, three of the products tested – a moisturizer, a blush and a powder sunscreen – had nanoparticles and three – two powders and a finishing powder – did not. The nose "breathed in" the air with the makeup powder, much as someone would while putting on cosmetics. The researchers measured the size and distribution of the particles in the products and in the air that was drawn up through the tube nose.

Only some of the nanoparticles were breathed in as individual particles. More often, the particles clung together and were inhaled as a larger clump – what the authors call an agglomeration of particles.

These larger particles may move through the body differently from single ones and may have different health effects. Future safety testing should include both grouped and individual particles to guarantee effects are not missed, the authors suggest.

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