Case Studies in Nanotoxicology and Particle Toxicology (eBook)

Antonietta M Gatti, Stefano Montanari (Autoren)

eBook Download: PDF | EPUB

2015 | 1. Auflage
276 Seiten
Elsevier Science (Verlag)
978-0-12-801254-3 (ISBN)

Infos

Case Studies in Nanotoxicology and Particle Toxicology presents a highly-illustrated analysis of the most prominent cases on the adverse effects of nanoparticles and their impact on humans and the environment. This comprehensive reference demonstrates the possible risks imposed by managing and handling nanoparticles, showing the effects of involuntary inhalation or ingestion during their use and after their incineration. Through the use of numerous examples, readers will discover the possible risks and effects of working with nanoparticles, along with best practices to prevent these effects. The text is an essential reference for anyone working in the risk assessment of nanoparticles, including nanosafety professionals, occupational toxicologists, regulatory toxicologists, and clinicians. - Presents real-life cases showing the potential risks to human health following exposure to nanoparticles - An ideal reference for anyone working in the risk assessment of nanoparticles, including nanosafety professionals, occupational toxicologists, regulatory toxicologists, and clinicians - Provides examples to help assess risks of handling engineered nanomaterials - Advises on the best forms of protection and the safest nanotechnological products

Textauszug

Chapter 2

A Very Brief History of Particulate Pollution

Abstract

Natural dust has always been part of the environment as a pollutant. Man started, though at first imperceptibly, to pollute the planet when he learned how to light a fire, but since the first Industrial Revolution rapidly increasing quantities of dust have come from man’s activities and are being introduced at alarming levels. Besides natural dust, some of the particles present in today’s environment derive from low-temperature sources but most of them originate from combustion since most of today’s technologies are based on or require high temperature and, as a consequence, produce particulate matter. Whatever their origin, their effects on health and the environment are harmful.

Keywords

Dust

pollution

combustion

primary particles

secondary particles

Industrial Revolution

bioenergy

Contents

2.1 Origin 7

References 10

2.1. Origin

Man has lived in a dusty environment all along, an environment that grows dustier everyday with pollution directly related to the increase in human activity (industrial processes, traffic, disasters, etc.). As briefly mentioned in the previous chapter, for hundreds of millennia dust was exclusively from natural sources: rock and soil erosion, sand carried by the wind, volcanic fumes and the smoke of occasional wood fires. It was the discovery of how to light, keep and use fire – something that occurred long after man was present on the Earth in a more or less now recognizable form, and probably his most important technological breakthrough ever – that introduced artificial pollution into the environment.

Along with gases, every combustion generates particles whose composition depends on what is being burned and whose shape and size depend mainly, though not only, on the temperature at which that combustion occurs. Some of them are formed immediately at the combustion site, and some are formed by condensation, as soon as the chemical elements or molecules are set free in the fire and find a cold enough temperature away from the fire in which they come from. As a general rule, the mostly-metallic particles generated directly by combustion (the ones that are part of the focus of our treatment), are spherical and hollow with a size that decreases with the raising of the formation temperature, ranging from a few tens of microns down to some tens of nanometers. Their crust, often very thin, is usually crystalline and particularly fragile, so that it breaks easily into minute fragments. Other particles, called secondary as opposed to the primary ones just briefly described, are produced at a distance from the combustion site and after some time through photochemical condensation of gases such as nitrogen oxides, sulphur dioxide, ammonia and volatile organic compounds with water vapor, ozone and free radicals more or less naturally present in the atmosphere.

So, environmental pollution is composed of micro- and nanosized particulate matter (PM) generated by natural processes [1], added to which today’s environment contains large quantities of other pollutants derived from industrial activities, high-tech nanotechnological productions [2,3], combustions in general [1,4], waste incineration [5,6], engines [7], etc.

Dust is a natural component of the Earth and has always been a part of human life, but it is also something that could be the cause, or one of the causes, of its end. As it is written in the Bible: “Remember, thou art dust and to dust thou shalt return” (“Memento homo, quia pulvis es et in pulverem reverteris”) (Genesis 3:19).

Of course, we are not religious exegetes and it is very likely that this phrase was not intended as a sort of planetary prophecy, although catastrophic effects have already occurred in the world’s history. In fact, life on Earth came to a sort of eye-catching standstill when dinosaurs disappeared in a very short time about 65 million years ago. There are many theories that try to explain this event. Walter Alvarez of the University of California at Berkeley is well-known for having hypothesized that a large extraterrestrial object collided with the Earth, and its impact threw up enough dust to cause a climatic change. Another theory considers dust, in this instance coming from a mass volcanism phenomenon, as triggering global changes not compatible with the life of great reptiles, for many millions of years the actual lords of the planet. No matter what happened then, dust in the atmosphere above a certain density is incompatible with the type of life we know [8]. It is obvious then that, whatever happens, the Earth will find another equilibrium. The only problem for us is if and how we can adapt to a new scenario.

As a matter of fact, today global industrial activity is generating a never-experienced-before mass of dust and what is more noteworthy is that that mass is increasing rapidly, particularly in emerging, developing countries where tumultuous economic development takes place without concern for health or the environment. On the other hand, the rest of the developed world is happy to buy goods at extremely cheap prices, apparently without realizing that such a policy is bound to be disastrous for the whole planet, since cheap means also uncontrolled. In addition to that, the Earth is much smaller than it looks, so its poisoning is not limited to confined areas and will sooner or later spread everywhere. As long as that problem remains unsolved, the pathologies caused by pollution will continue to rise steadily and inexorably.

Man lived for thousands of centuries like any other primate, without impacting on the world he inhabited. It was only when he discovered how to light a fire that man, at first imperceptibly, started to stain the planet. The quantity and concentration, especially in urban areas, of PM, though, could be considered negligible until the so-called Industrial Revolution between the eighteenth and nineteenth century. Then it started to increase in the environment at an accelerating pace and is now at objectively alarming values. Internal-combustion engines (i.e., mainly vehicular traffic, factories, foundries, cement works, power plants burning heavy oil, coal or biomass, waste incinerators) are all agents unknown until not long ago and responsible for particulate pollution, a kind of pollution that is partly irreversible since a considerable fraction of the matter generated as an unwanted by-product is neither degradable nor technically possible to isolate once it has been released into air, water and soil.

The Great Smog of 1952, or Big Smoke, was a severe air pollution event that affected London during December 1952 [9]. Medical reports in the following weeks estimated that no less than 4,000 people died prematurely and 100,000 more were made ill because the smog’s effects on the human respiratory tract. More recent research suggests that the number of fatalities was considerably greater at about 12,000 [10].

As stated above, all combustive processes are a source of particles. So, the so-called “bioenergy,” a form of energy obtained by burning biomasses like agriculture waste or poultry droppings, does not represent by any means an exception, and the bio prefix should be looked at as rather suspicious not as much for the origin of the sources of energy, but for the effects of the industrial process on the environment.

Particles can also be produced unintentionally at low temperatures by mutual friction of hard objects. An example may be that of car brakes with pads rubbing on disks. In those cases the PM shapes are irregular, and the size ranges from nanometric to rather coarse. Metal milling, turning and polishing are further cold sources of PM as well as the artefacts from aging buildings.

But, as already mentioned, not all particles, especially nanosized ones, have unintentional origin. With the discovery of the extraordinary physical characteristics of nanoparticles and the advancement of Nanotechnology, higher and higher quantities and more and more various compositions of particles both in the micro and nano range are constantly being introduced into the market and, as an obvious consequence, into the environment by laboratories set up for the purpose. If their presence is dwarfed by what comes from traffic, industry and incineration, it is not hard to see that this will indeed soon change. However, engineered micro- and nanoparticles currently being added to some food, drugs and cosmetics are a component of an increasing number of high-tech yarns, sports equipment, paints, glasses, etc.

The quantity of submicronic particles released into the air is constantly on the increase. While until a few decades ago the nanosized fraction of PM was comparatively low or, in any case, restricted to some industrial areas (steel melting industries, laser ablation technique, laser soldering, etc.), today other activities like those briefly listed above release an increasing quantity of dust into the air we inhale. Because of that, the exposure to every breathing creature grows every day from a safe level and that exposure increases the probability of a noxious interaction with our body and our internal organs. Human life is based essentially on the O2/CO2 exchange, and dust can conflict with this basic mechanism. The accumulation of these foreign bodies creates...

Produkt-Details

• Erscheint lt. Verlag: 29.5.2015
• Sprache: englisch
• Themenwelt: Medizin / Pharmazie ► Gesundheitsfachberufe
• Themenwelt: Studium ► 2. Studienabschnitt (Klinik) ► Pharmakologie / Toxikologie
• Themenwelt: Studium ► Querschnittsbereiche ► Prävention / Gesundheitsförderung
• Themenwelt: Technik
• Themenwelt: Wirtschaft
• ISBN-10: 0-12-801254-4 / 0128012544
• ISBN-13: 978-0-12-801254-3 / 9780128012543