Nanoparticles Used in Common
Household Items Cause DNA Damage
Titanium dioxide (TiO2) nanoparticles, found in everything from
cosmetics to sunscreen to paint to vitamins, caused systemic genetic
damage in mice, according to a comprehensive study conducted by
researchers at UCLA's Jonsson Comprehensive Cancer Center.
The TiO2 nanoparticles induced single- and double-strand DNA
breaks and also caused chromosomal damage as well as inflammation,
all of which increase the risk for cancer. The UCLA study is the
first to show that the nanoparticles had such an effect, said
Robert Schiestl, a professor of pathology, radiation oncology
and environmental health sciences, a Jonsson Cancer Center scientist
and the study's senior author.
Once in the system, the TiO2 nanoparticles accumulate in different
organs because the body has no way to eliminate them. And because
they are so small, they can go everywhere in the body, even through
cells, and may interfere with sub-cellular mechanisms.
The study appeared the week of November 16 in the journal Cancer
In the past, these TiO2 nanoparticles have been considered non-toxic
in that they do not incite a chemical reaction. Instead, it is
surface interactions that the nanoparticles have within their
environment- in this case inside a mouse -- that is causing the
genetic damage, Schiestl said. They wander throughout the body
causing oxidative stress, which can lead to cell death.
It is a novel mechanism of toxicity, a physicochemical reaction,
these particles cause in comparison to regular chemical toxins,
which are the usual subjects of toxicological research, Schiestl
"The novel principle is that titanium by itself is chemically
inert. However, when the particles become progressively smaller,
their surface, in turn, becomes progressively bigger and in the
interaction of this surface with the environment oxidative stress
is induced," he said. "This is the first comprehensive
study of titanium dioxide nanoparticle-induced genotoxicity, possibly
caused by a secondary mechanism associated with inflammation and/or
oxidative stress. Given the growing use of these nanoparticles,
these findings raise concern about potential health hazards associated
The manufacture of TiO2 nanoparticles is a huge industry, Schiestl
said, with production at about two million tons per year. In addition
to paint, cosmetics, sunscreen and vitamins, the nanoparticles
can be found in toothpaste, food colorants, nutritional supplements
and hundreds of other personal care products.
"It could be that a certain portion of spontaneous cancers
are due to this exposure," Schiestl said. "And some
people could be more sensitive to nanoparticles exposure than
others. "I believe the toxicity of these nanoparticles has
not been studied enough."
Schiestl said the nanoparticles cannot go through skin, so he
recommends using a lotion sunscreen. Spray-on sunscreens could
potentially be inhaled and the nanoparticles can become lodged
in the lungs.
The mice were exposed to the TiO2 nanoparticles in their drinking
water and began showing genetic damage on the fifth day. The human
equivalent is about 1.6 years of exposure to the nanoparticles
in a manufacturing environment. However, Schiestl said, it's not
clear if regular, everyday exposure in humans increases exponentially
as continued contact with the nanoparticles occurs over time.
"These data suggest that we should be concerned about a
potential risk of cancer or genetic disorders especially for people
occupationally exposed to high concentrations of titanium dioxide
nanoparticles, and that it might be prudent to limit their ingestion
through non-essential drug additives, food colors, etc.,"
the study states.
Next, Schiestl and his team will study exposure to the nanoparticles
in mice that are deficient in DNA repair, to perhaps help find
a way to predict which people might be particularly sensitive
The study was funded by the National Institutes of Health.
Reference Source 128
November 17, 2009