This Swiss study looks at the effect of two kinds of nanoparticles, separately and combined. Both copper oxide (CuO) and titanium dioxide (TiO2) ultrafine particles (nanoparticles or NP) are widely used in many things from paint and electronics to makeup, food, and paper. Much of it is released into the water, so the authors chose to see what these two chemicals do to fish. Applying each chemical separately and both together to different groups of carp, they determined that they not only reacted to each chemical separately, but when exposed to both together they reacted much more strongly. Their swimming behavior was abnormal; the had convulsions, hyperactivity, loss of balance, and increased surfacing activity compared to the controls (fish not exposed to the chemicals).
If it weren’t that they obviously suffered in this study, I would be amused at the thought of the fish becoming hyperactive. However, a search of MedLine for “ADHD TiO2” came up with nothing at all. I will keep watching for it and bring it to the blog as soon as I can find something.
When examining the tissues and organs of these fish, Mansouri et al found an increased number of blood cells, degeneration and death of cells, damage and swelling of the gills and intestine, and abnormalities of the kidneys and liver.
CONCLUSION: “More studies are needed to evaluate the behavior of NP coexistence with other pollutants to understand the potential risks of environmental pollution by NPs.”
NOTE: See a study by Jovanovic et al (2016) in which the researchers found that environmentally relevant concentrations of TiO2 have no effect on the overall function of the ecosystem.