Environmental Engineering Reference
In-Depth Information
of pathologies, but it must be said that they, as particles taken for long periods in
small quantities do, could take a long time before their adverse effects grow
manifest. Besides, it is at least unusual that the etiology of a disease is attributed
to something occurred many years ago and Silver could be considered free from
blame simply because no one thinks of it. However, the FDA issued a Final Rule
declaring that all over-the-counter drugs containing colloidal Silver or Silver salts
are not recognized as safe and effective and are misbranded [
3
].
But even if national and international regulatory organizations (ISO, OECD, etc.)
are actively working with the aim of governing the subject (from definitions to
nomenclature, from tests to devising prevention measures), market runs much faster
than regulators. Therefore, taking advantage from the virtual absence of rules,
nanoproducts are blindly invading the market, blindly because no one really knows
the land on which we are all treading. In short, we do not know whether the risks
brought about by engineered nanoparticles outweigh their benefits for society
[
4
]. What we are sure of is that confusion is rampant: research needs money and
time, two things on which no one seems willing to invest, and the lack of knowledge
hinders the regulators who are often forced to act extrapolating from other,
non-specific knowledge. On the other hand, end-users are kept unaware not only of
the potential dangers they could encounter, but in many cases they do not even know
that they are using a nanoproduct, since declaring their presence is not mandatory for
manufacturing companies. So, many of them prefer not to let their customers know
what they are buying, lest they would refuse the purchase. Even people who work in
laboratories where nanoparticles are engineered not always handle them with due
care. As to investors and manufacturers, they too are at risk. Should nanoproducts be
proven to be really dangerous, the economic loss would be a certitude.
If, from the health point of view, we do not know much about engineered
particles, we know that unintentionally made nanoparticles, i.e. those generated
by car traffic, waste incinerators, factories working at high temperature, etc. are
extremely invasive and can rather easily enter the organism where they are the
documented responsible for deleterious reactions. We know that they are inhaled
and ingested, that they can cross the lung and digestive-system barriers and enter
the blood stream where, in particular conditions, they can have the blood clot. Then,
carried by the blood, they can reach virtually any organ and tissue where they are
trapped without having the possibility of being expelled. And we also know that
they can cross the cell membrane and enter the nucleus. In any case, they are foreign
bodies and so they are perceived by the organisms. There is no reason why
engineered particles should be different in their behavior.
Like never before, the environment we are living in contains huge quantities of
micro- and nanoparticles, and very unusual ones, at that. The images that follow
demonstrate their extreme invasiveness, showing engineered and incidental parti-
cles embedded in pathological tissues. The images were obtained by means of a
novel ultramicroscopic technique developed by using a Field-Emission-Gun Envi-
ronmental Scanning-Electron Microscope (FEG-ESEM Quanta 250, FEI, the Neth-
erlands) and an X-ray microprobe of an Energy Dispersive Spectroscopy (EDS by
