Nanotoxicity in Regulatory Vacuum

A vast and rapidly expanding array of engineered nano-
products floods the consumer market unregulated as evidence
of toxicities accumulate. Dr. Mae-Wan Ho

First cases of nanotoxicity occupational exposure

Seven young women (aged 18–47yrs) working in a paint factory
and exposed to nanoparticles for 5–13months fell ill and
were admitted to hospital. Two subsequently died.
Pathological examinations of the patients' lung tissue
showed nonspecific inflammation, fibrosis and foreign-body
granulomas (tumours resulting from inflammation) of the
pleura (membrane around the lungs). Transmission electron
microscopy revealed nanoparticles of polyacrylate lodged in
the cytoplasm and the nucleus of cells and in the chest
fluid [1]. The polyacrylate nanoparticles were confirmed in
the workplace.

These first suspected cases of nanotoxicity from
occupational exposure have heightened concerns over the huge
and rapidly expanding array of nanotechnology products in
the market that remains unregulated despite accumulating
evidence that many nano-ingredients, including those most
common in commercial use, are indeed toxic.

Common nano-ingredients are toxic

Nanotechnologies are technologies at the scale of nanometres
(10-9m), where new quantum effects can alter the chemistry
and physics of elements and compounds, offering exciting new
possibilities in industrial applications, and for exactly
the same reasons, posing unprecedented risks to health and
the environment.

It was difficult to separate hype from reality when it all
began, and almost no one worried about safety [2]
(Nanotechnology, a Hard Pill to Swallow, SiS 16). But
evidence of health hazards soon started to emerge [3-5]
(Nanotox, Metal Nanoshells, Cure or Curse?, Nanotubes Highly
Toxic, SiS 21), and nanotoxicology became established as a
discipline in 2005 [6] (Nanotoxicity: A New Discipline, SiS
28). By then, many serious health impacts had already been
observed in laboratory experiments; and more appeared in
subsequent years. I describe a few recent examples below.

In 2009, researchers at University of California Los Angeles
Jonsson Cancer Center led by Robert Schiest reported that
[7] titanium dioxide nanoparticles (TiO2), found in
“everything from cosmetics and sunscreens to paint and
vitamins” (see Box), caused DNA damage when fed to mice.
They induced breaks in DNA, damaged chromosomes, and caused
inflammation of tissues; “all of which increase the risk of
cancers.”

The mice were exposed to the nanoparticles in their drinking
water, and genetic damage started showing up on the fifth
day [8], equivalent to occupational exposure in humans of
1.6 years. Once taken into the body, the TiO2 nanoparticles
accumulate in different organs because the body cannot
eliminate them, and they are so small that they can go
everywhere.

These latest findings confirm the results of numerous other
studies indicating that nano-TiO2 increases cell death, DNA
damage, and genome instability in the short-term and the
risk of cancer in the longer term. A team of researchers at
several institutes in Taiwan showed that exposing mammalian
cells to TiO2 nanoparticles at 10 ppm in the short-term
(days) resulted in enhancement of cell growth and survival,
and increase in reactive oxygen species (oxidative stress).
In the long-term – after 12 weeks - a dramatic increase in
transformed (cancerous) cells was observed, resulting from a
disturbance of cell division and genome instability [9].
Similar toxicities have been found for other nanoparticles
often used with TiO2, such as ZnO2 and SiO2 [10, 11].