In combination with silver chloride, antibacterial pads are made ^[3]. Microcrystalline cellulose, however is used as a food additive E460 and also in the pharmaceutical industry. It serves as dietary fibre for low-calorie foods, as a release agent or as a carrier. There are reservations against the use of microcrystalline cellulose in the food sector, e.g. for the production of sauces and low-calorie preparations, because the intestinal walls are permeable for microcrystalline cellulose. In pharmacy, it is applied as a binder and carrier for the manufacture of pills ^[4].

Literatur:

1. Eyholzer, C et al (2011) Biomacromolecules 12 (5), 1419–1427
   
2. Borges, AC et al (2011) Acta Biomaterialia 2011
   
3. Klemm, D et al (2011) Angew Chem Int Ed Engl, Volume 50, Issue 24, pages 5438–5466
4. Mikrokristalline Cellulose : Roempp online

This effect is due to the strong binding of the cellulose fibers to water, which thus is removed from the environment ^[1]. If, however, sufficient water for bacterial growth is present, microorganisms can also be used for the production of nano-cellulose. The enzymatic activity of bacteria and fungi is used for the secession of single nano-cellulose fibers from the complex networks of naturally occurring cellulose.
In the luminescent bacteria test nanocellulose caused no acute toxicity, even though high concentrations were used. A NOEC of ≥ 100 mg/l was derived. However, nano-cellulose fibers limited the movement of water fleas. This effect is due to the non-uniform distribution of fibers in water and is purely mechanical in nature. There is no evidence of a direct toxic effect of nano-cellulose ^[2].
After a comprehensive toxicological characterisation of nano-crystalline cellulose in nine aquatic species (including fish, water fleas, algae) of various stages of development and in a rainbow trout liver cell line, no harmful potential to aquatic inhabitants was identified ^[3]. There was no, or only a low toxicity observed in experiments.

Literature:

1. Wikipedia - Nanocellulose.
2. Vartiainen J et al., 2011, Cellulose, 18, 775-786.
   
3. Kovacs T et al., 2010, Nanotoxicology, 4, 255-270.