Nanoobjects are suspected of being more toxic than a similar mass of fine particulates of the same material. Their size is 1–100 nanometers. One nanometer is equivalent to one billionth of a meter. For comparison, consider that a human hair is about 50,000 nanometers thick and that a DNA strand is about two nanometers thick.
About 100 publications on nanotoxicology have appeared. However, the data they are based on is rather heterogeneous because the composition, form, and surfaces of the objects studied – along with the duration of the studies themselves and the effects they considered – differ quite a bit. This situation complicates a reliable toxicological assessment.
At the request of the German Federal Environment Agency, researchers at the Fraunhofer Institute developed a database on particle and fiber toxicity (PaFtox). It enables comparisons of data from individual studies, thereby making it possible to evaluate the toxicity of nanoobjects.
The researchers evaluated more than 100 studies that examined the effects of carbon black, silicon dioxide, and metals or metal oxides on rodents. The results? Nanoobjects caused pneumonia more quickly and at lower doses than particles in microscale. Silver showed the highest potential for toxicity among the metals.
The studies also showed that chronic inflammation can be a precursor to cancer. The scientists encourage future grouping of nanomaterials based on their potential to cause inflammations.
The complete study is available for download here.