The risks that nanosilver poses to the environment need to be more stringently examined, said a new report partly conducted by Australian scientists published on Friday.

The literature review was conducted by Swiss Federal Laboratory for Materials Science and Technology, as well as Australian National University (ANU).

According to Professor Thomas Faunce, research council future fellow studying nanotechnology and public health at the ANU, silver is regarded as harmless to humans unless it is present in high concentrations, but it is toxic to microorganisms like bacteria and viruses.

"Nanosilver is the nanotech substance most widely spread in consumer products. There's a large amount of it being used in clothing, washing machines and all sorts of applications that could end up in our water ways", Professor Faunce told ABC Science on Friday.

"The problem is that while we've known for a long time that silver is a very potent biocide, nanosilver appears to have a quite unique toxicity purely because of its size."

The physical and chemical properties of particles in the nano- range can be different from larger particles or dissolved compounds, and the report said due to different properties, there should be "a new and more rigorous human and environmental risk assessment."

The review also raised concern that the sludge and wastewater from treatment plants are often sold to farms as fertilizer. From there nanosilver could potentially enter the food chain.

Dr Bernd Nowack, of Empa, the Swiss Federal Laboratory for Materials Science and Technology said pollution to food chain is not the only potential problem with nanosilver entering the sewage system.

"There are major concerns because our sewerage systems work using nitrifying bacteria. If the silver gets into those systems it may inhibit them working properly," he told ABC Science, adding that the use of nanosilver in consumer goods, therefore is currently under intense scrutiny from occupational scientists and regulators, as they try to determine exactly how toxic the substance is.

The review has published in the journal Science.