This is a photo of Thiago Verano-Braga. Image: Birgitte Svennevig, Univ. of Southern DenmarkEndocrine disrupters are not the only worrying chemicals that ordinary consumers are exposed to in everyday life. Nanoparticles of silver — found in dietary supplements, cosmetics, food packaging and more — also worry scientists. A new study from the Univ. of Southern Denmark shows that nanosilver can penetrate our cells and cause damage.

Silver has an antibacterial effect and the food and cosmetic industry often coat their products with silver nanoparticles. Nanosilver can be found in drinking bottles, cosmetics, bandages, toothbrushes, running socks, refrigerators, washing machines and food packaging.

"Silver as a metal does not pose any danger, but when you break it down to nanosizes, the particles become small enough to penetrate a cell wall. If nanosilver enters a human cell, it can cause changes in the cell," explain Associate Prof. Frank Kjeldsen and Thiago Verano-Braga, Department of Biochemistry and Molecular Biology at the Univ. of Southern Denmark.

Together with their research colleagues they have just published the results of a study of such cell damages in the journal ACS Nano.

The researchers examined human intestinal cells, as they consider these to be most likely to come into contact with nanosilver, ingested with food.

"We can confirm that nanosilver leads to the formation of harmful, so called free radicals in cells. We can also see that there are changes in the form and amount of proteins. This worries us," say Kjeldsen and Verano-Braga.

A large number of serious diseases are characterized by the fact that there is an overproduction of free radicals in cells. This applies to cancer and neurological diseases such as Alzheimer's and Parkinson's.

Kjeldsen and Verano-Braga emphasizes that their research is conducted on human cells in a laboratory, not based on living people. They also point out that they do not know how large a dose of nanosilver, a person must be exposed to for the emergence of cellular changes.

"We don't know how much is needed, so we cannot conclude that nanosilver can make you sick. But we can say that we must be very cautious and worried when we see an overproduction of free radicals in human cells," they say.

Nanosilver is also sold as a dietary supplement, promising to have an antibacterial, anti-flu and cancer-inhibitory effect. The nanosilver should also help against low blood counts and bad skin. In the EU, the marketing of dietary supplements and foods with claims to have medical effects is not allowed. But the nanosilver is easy to find and buy online.

In the wake of the Univ. of Southern Denmark-research, the Danish Veterinary and Food Administration is warning against taking dietary supplements with nanosilver.

"The recent research strongly suggests that it can be dangerous," says Søren Langkilde from the Danish Veterinary and Food Administration to the Danish Broadcasting Corporation (DR).