BfR Annual Report 2015

Food Safety

Cellular intake of silver nanoparticles

resorption area for nutrients and, where applicable, also

for nanoparticles. This membrane also acts as an effec-

tive barrier to substances that should not enter the blood

stream and other organs. The investigation showed that

the transport of these particles is mostly prevented by

an intact intestinal mucous membrane and that only a

small quantity of the particles therefore pass the intesti-

nal barrier and enter the blood stream. However, regular

intake of larger quantities of nanosilver in food supple-

ments can result in an overdose and therefore in damage

to the barrier function of the intestinal mucosa. The con-

sequences of this kind of long-term intake on the human

body and in particular on the organs are still unclear. It is

also for this reason that the BfR advises against the use

of nanosilver in consumer products.

The study findings were published in the journal

Biological Chemistry.

(DOI: 10.1515/hsz-2015-0145)

One of the questions addressed by BfR researchers was

how nanoparticles behave in the gastrointestinal tract

during the digestion process. It has not been clear up to

now whether nanoparticles dissolve here, for example,

or whether they clump together to form larger particles,

thus losing their specific toxicological properties and

small size.

In order to answer this question silver nanoparticles were

artificially digested in a purpose-modified system. The

conditions that exist in the oral cavity, the stomach and

the intestines were simulated, and the size of the parti-

cles in the digestive juices then examined. It was found

that the size of the nanoparticles hardly changes at all

during passage through the gastrointestinal tract. The

next step was to investigate the effect of the particles on

model cells of the mucous membrane of the small intes-

tine. The mucous membrane of the intestine is the largest

Microvilli

Silver nanoparticles

In the rat

In cell culture

Small intestine cross-section

Silver nanoparticles

1 µm

Intestinal lumen

Cell nucleus

Intestinal cells