Nanotechnology safety studies blasted for their bad science
10 November 2014
A scientist at the Swiss Federal Laboratories for Materials
Science (Empa), toxicologist Harald Krug, has criticised fellow
scientists studying the safety of nanoparticles for their poorly
prepared experiments, results that do not stand up scientifically
and even for cruelty to animals.
In a study published in the journal Angewandte Chemie he
evaluated several thousand studies on the risks associated with
nanoparticles and discovered a high level of shortcomings. As a
result, Empa is developing new standards for such experiments within
an international network.
Thousands of scientists worldwide are conducting research
on the topic, such as examining whether titanium dioxide
nanoparticles from sun creams can get through the skin and into the
body, whether carbon nanotubes from electronic products are as
hazardous for the lungs as asbestos used to be, or whether
nanoparticles in food can get into the blood via the intestinal
flora, for instance.
Along with growing public interest and research funds flowing
into the topic area, the number of scientific projects is
skyrocketing: between 1980 and 2010, a total of 5,000 projects were
published, followed by another 5,000 in just the last three years.
However, the amount of new knowledge has only increased marginally
because, according to Krug, the majority of the projects are poorly
executed and all but useless for risk assessments.
Iron oxide nanoparticles on the surface of a
How do nanoparticles get into the body?
Artificial nanoparticles measuring between one and 100 nanometers
in size can theoretically enter the body in three ways: through the
skin, via the lungs and via the digestive tract. Almost every study
concludes that healthy, undamaged skin is an effective protective
barrier against nanoparticles. When it comes to the route through
the stomach and gut, however, the research community is at odds.
But upon closer inspection the value of many alarmist reports is
dubious — such as when nanoparticles made of soluble substances like
zinc oxide or silver are being studied. Although the particles
disintegrate and the ions drifting into the body are cytotoxic, this
effect has nothing to do with the topic of nanoparticles but is
merely linked to the toxicity of the (dissolved) substance and the
Laboratory animals die in vain
Krug also discovered that some researchers maltreat their
laboratory animals with absurdly high amounts of nanoparticles.
Chinese scientists, for instance, fed mice five grams of titanium
oxide per kilogram of body weight, without detecting any effects. By
way of comparison, half the amount of kitchen salt would already
have killed the animals.
Poor research was also conducted in the study of lung exposure to
nanoparticles: inhalation experiments are expensive and complex
because a defined number of particles has to be swirled around in
the air. Although it is easier to place the particles directly in
the animal’s windpipe (“instillation”), some researchers overdo it
to such an extent that the animals suffocate on the sheer mass of
While others might well make do without animal testing and
conduct in vitro experiments on cells, here, too, cell
cultures are covered by layers of nanoparticles that are 500
nanometers thick, causing them to die from a lack of nutrients and
oxygen alone — not from a real nano-effect.
And even the most meticulous experiment is worthless if the
particles used have not been characterized rigorously beforehand.
Some researchers simply skip this preparatory work and use the
particles “straight out of the box”. Such experiments are
irreproducible, warns Krug.
The solution: inter-laboratory tests with standard
Empa is thus collaborating with research groups like EPFL’s
Powder Technology Laboratory, industrial partners and with
Switzerland’s Federal Office of Public Health (FOPH) to find a
solution to the problem: on 9 October the “NanoScreen” programme,
one of the “CCMX Materials Challenges”, got underway, which is
expected to yield a set of pre-validated methods for lab experiments
over the next few years.
It involves using test materials that have a closely defined
particle size distribution, possess well-documented biological and
chemical properties and can be altered in certain parameters such as
“Thanks to these methods and test substances, international labs
will be able to compare, verify and, if need be, improve their
experiments,” explains Peter Wick, Head of Empa’s laboratory for
Instead of the all-too-familiar “fumbling around in the dark”,
this would provide an opportunity for internationally coordinated
research strategies to not only clarify the potential risks of new
nanoparticles in retrospect but even be able to predict them.
The Swiss scientists will therefore coordinate their research
activities with the National Institute of Standards and Technology
(NIST) in the US, the European Commission’s Joint Research Center
(JRC) and the Korean Institute of Standards and Science (KRISS).