The study highlights one of the challenges our water systems face as new materials enter the water supply.
In the journal Environmental Engineering Science, researchers from the University of California (UC), Riverside, describe how they arrived at their conclusions after examining one engineered nanoparticle in particular - titanium dioxide.
Nanomaterials are not new - nature is full of tiny particles that are so small you have to use measurements on the scale of atoms and molecules to size them. However, nanotechnology is new, and is creating new types of materials either not present or uncommon in nature.
Engineered nanomaterials are attractive to scientists and technologists because they can be manipulated at the level of atoms and molecules to evince remarkable and unique qualities not present in their large-scale form.
These engineered nanomaterials are a fast growing class of contaminants because they are increasingly being used in industries like energy technology, and to make goods like cosmetics, drugs, electronics and sunscreens.
'Significant concern' about potential health risks of engineered nanomaterials
The authors note there is "significant concern" about the potential health and environmental risks of engineered nanomaterials such as the one they chose to study - titanium dioxide, and say some studies have found one form of the nanomaterial is linked to oxidative stress in human cells and others that it is toxic to various surface water organisms.
The team chose to study titanium dioxide because it is the most widely used engineered nanomaterial - it is found in a wide range of products including paints, cosmetics, coatings and advanced ceramic and semiconductor materials for energy and environmental applications.
Also, they note that unlike other engineered nanomaterials, more than half of globally produced titanium dioxide is expected to enter waste water either directly from cosmetics, or indirectly from other uses.
For their study, the researchers used scaled-down versions of three stages typically used in water treatment plants to test their effectiveness in removing titanium dioxide nanoparticles. The three stages are: coagulation, flocculation and sedimentation.
Study found 'possibility for significant release' of titanium dioxide nanoparticles
The team notes that their results showed that "under realistic water chemistries there is a possibility for significant release," of titanium dioxide nanoparticles. They observed doses of around 5 parts per million of particles smaller than 450 nanometer after sedimentation.
Senior author Sharon Walker, professor of Chemical and Environmental Engineering at UC-Riverside, says:
"While further optimization of such treatment processes may allow for improved removal efficiencies, this study illustrates the challenges that we must be prepared to face with the emergence of new engineered nanomaterials."
In November 2014, Medical News Today learned of a new report from the World Health Organization on behalf of UN-Water that suggests water and sanitation in rural areas are seriously underfunded. The report says while billions of people worldwide today have much better access to clean water and sanitation, some serious funding gaps are holding back progress - particularly in rural areas.