Environmental Engineering Reference
In-Depth Information
obvious that something that behaves that way cannot be considered biocompatible.
A few analyses carried out on thrombi extracted from the coronary arteries the first
day after a myocardial infarction revealed the presence of inorganic foreign bodies
inside the thrombus, and so did the analyses of venous thrombi captured by vena-
cava filters. But, in the majority of circumstances, the particles that are carried by
the blood reach virtually any organ—impossible, as far as we know, to foretell the
butt—and those organs, with very little differences, behave like mechanical filters,
capturing that solid matter [
11
,
12
].
Ingestion is another doorway for particles. In that case those that are in touch
with the wall of the digestive system long enough can negotiate that barrier and
enter the blood circulation, thus sharing their lot with the ones passed through the
lungs. According to what we observed, the digestive system allows the passage of
particles much bigger than those entered through inhalation.
But inhalation and ingestion are not the only possibility for particles to get into
the organism. We found particulate pollutants in injectable preparations and it is
only obvious that those will be introduced in the organism of the subject receiving
the injection. And we have also found them as additives in cosmetics. In that case,
we have no solid-enough evidence to say that they can negotiate the skin barrier,
this remaining one of the many aspects of particle behavior to be clarified.
G. Oberd¨rster [
13
] demonstrated that nanoparticles can move along the olfac-
tory nerve and it will not be a surprise if also other nerves or even all nerves could
host the same phenomenon.
Anyway, no matter how they got there, in the course of our research we keep
finding micro- and nano-sized particles in all organs: the liver, the kidney, the
spleen, the brain, the gonads, the thyroid, the lymph nodes. We find them even
inside cell nuclei in contact with DNA and that can induce DNA damages [
14
,
15
].
Most particles are not biodegradable, i.e. they are bio-persistent and, once they
have been imprisoned by a tissue, cannot be expelled, since no such mechanism
exists. Their permanence in the tissue can activate physico-chemical reactions that,
over time, are likely to induce adverse effects.
In some instances, particles tend to concentrate and, in that particular situation,
the tissue that hosts them perceives them as foreign bodies—as they actually are—
and starts the classical foreign-body reaction, with the formation of a granulation
tissue and the establishment of a chronic inflammatory condition. According to the
current medical literature and to our experience, in the long run a chronic inflam-
mation with such characteristics can be the cause of a cancer [
16
,
17
].
How long the phenomenon will take to be completed is hard to foretell. What we
can say in keeping with what we have seen in the more than 2,000 human cases we
had a chance to analyze so far, is that particularly intense exposures to particles can
induce a cancer in a matter of months. Slow, diluted, chronic exposures can take
many years or even, though we have no evidence but it is just a matter of
speculation, so long as to exceed the natural lifespan of the subject.
It is a fact that cardiovascular accidents and cancer in many different varieties
are the most common adverse effects particles can bring about in the organism, but
they are not alone.
