According to the pieces of evidence we got, the blood and the lymph are the obvious carriers of the particles that are then filtered by organs like the liver and the kidneys. Circulation is a “closed” system and it is impossible to demonstrate the presence of rare foreign bodies dispersed in five or more litres of blood without introducing any pollution or interference by opening of the system. Thus, our Laboratory of Biomaterials had recourse to an indirect method that had the advantage of being cheap and free of external interactions. Some centres which implanted vena cava filters (vena cava filters are devices which are implanted within the lumen of the inferior vena cava to prevent thrombi from embolising to the pulmonary circulation) in patients actually suffering or in danger to suffer from deep vein thrombosis sent the explanted devices to the Laboratory. In the series checked, the filters had stayed in situ for periods ranging from 18 to 385 days. The thrombi the devices had captured were detached and processed in order to verify if foreign bodies were to be found there, a thing that was proved in all cases.

Those were low-size particles, below 10 micron (a cell red has a 7-micron diameter) with a wide variety of compositions. Some of them, like barium sulphate, compounds of zirconium, compounds of iron or lead or silver, for example, had already been detected in other patients and in other districts. We did not have le possibility to check the lymph directly, but all the samples of lymph-nodes belonging to lymphoma patients we had the opportunity to observe contained inorganic particles.

Inside the thrombi examined we found particles made up of various compositions, such as talc, barium sulphate, steel, lead compounds and also silver, either alone or bound to mercury, tin and copper, a composition typical of dental amalgams. But in the blood, as well as in the other considered tissues, very unusual combinations were detected, that are not listed in any chemistry handbook. One of the possibilities as to their origin is a provenance from cement factories or incinerators where new compounds can form. The presence of foreign micro- and nano-particles in the blood was never documented before. It is hard to think that those objects, technically speaking emboli, can travel in the blood forever. So, sooner or later, they must settle somewhere. It is also reasonable to think that they are thrombogenic the way any foreign body is, and be the cause of at least some of the pulmonary embolism episodes in patients where a deep-vein thrombosis focus could not be demonstrated. As a matter of fact, the particles we detected where deeply embedded in the thrombus and not on their surface.

Debris of cobalt–tungsten found in a small thrombus grown in the blood stream.

Debris of basalt found in a cauliflower soup. The cauliflower was grown
under the fall-out of the Etna ashes during the 2002 eruption.

POLLUTION SOURCES
Pollution forms are very numerous and further sources keep being introduced by new technologies and new habits of life. Air pollution in geneal has long been suspected to induce lung diseases like granulomatoses and cancers, while other diseases like silicosis (specifically induced by silica) and asbestosis (specifically induced by asbestos) are more typical of a polluted working environment. It is so well-known a fact that air polluted by particulate matter the size of 10 microns, the so-called “PM-10”, is hazardous, and air polluted by “PM-2.5” (size below 2.5 microns) is even more so, that many countries have already taken legal measures to reduce that presence by limiting somehow the emission of fumes, by closing city areas to cars, etc.

Explosions as may occur in warfare, in military drills, in quarries or in any other environment, condition and circumstance are an important and aggressive pollution source. In some cases, the temperature produced as a consequence of military or industrial processes is high enough to form particles of previously unknown metal alloys, whose effects on the organism are still to be investigated. But natural pollution exists as well. During the latest eruption of the volcano Etna in Sicily, we found basalt particles on vegetables coming from the area close to the eruption site. Our analyses show that those particles that pollute the environment are breathed in and settle in the alveoli, and recently a Belgian group demonstrated that 2.5-micron particles can cross the alveolus barrier and enter the bloody stream within a minute to settle in the liver by the end of their observation time. (Those researchers used radiolabelled particles and they could follow them just for one hour.) It was also demonstrated that the curve describing the incidence of cardiovascular diseases follows very closely that of the increased and decreased presence of PM 2.5 particles in the environment. Not so for the PM10. Food may be a further pollution source. Micro and nanoparticles diffused in the atmosphere fall to the ground and settle on fruit and vegetables, which become food for men and animals. And pollutants are generally introduced, for example, into flour by the wearing of the grindstones. Very common in pharmaceutical technique is the use of talcum, silica and other inorganic particles added to tablets as excipients and of inorganic abrasives to tooth-paste and chewing-gum.

Particles coming from worn orthopaedic prostheses, dental ceramics and amalgams can be found in diseased organs.Tobacco smoke contains inorganic particles as well, and those particles may be both inhaled and absorbed through the oral mucosa. Penetrating the tissues, the particle advances as deeply as its size allows, and stops as soon as the filter offered by the tissue is thick enough. Particles larger than 20 microns and introduced through the digestive system, for example, are generally, though not always, entrapped by the intestinal mucosa where they induce an inflammatory reaction. If the particle floats in the blood, it can either be captured by a tissue whose filtering property (and here the term “filtering” has a mere physical meaning) is as high as needed, or reach the pulmonary circulation, or travel in the blood until it triggers a thrombotic reaction. On account of the homogeneity of the cases we observed, each tissue seems to show a certain chemical or size selectivity, but particles coming from the same pollution source are not necessarily to be found in the same organ in two different patients. It is very likely that an organ or tissue threshold concentration exists, and once that limit is exceeded, the tissue involved starts an “obvious” inflammatory reaction, generally a mild one, aimed at defending itself from the foreign aggression. Hence the granulomatoses and the start point of the other pathologies observed.
Some of the materials we find are defined biocompatible, but none is biodegradable. Some of them are certainly chemically toxic, like mercury or lead, and it is probable that they react with some of the chemicals present in the organism.