Health and Safety
Plastics degrade, albeit slowly, in all environmental settings by means of bio-degradation, photo-degradation, thermo-oxidative degradation or hydrolysis. Degradation is a chemical change that drastically reduces the average molecular weight of the polymer. Since the mechanical integrity of plastics invariably depends on their high average molecular-weight, any significant extent of degradation inevitably weakens the material. Weathering degradation of plastics results in their surface embrittlement and microcracking, yielding microparticles that continue on in the environment, known as 'microplastics.' Micro-plastics concentrate Persistent Organic Pollutants (POPs). The relevant distribution coefficients for common POPs are several orders of magnitude in favour of the plastic medium. Consequently, the micro-particles laden with high levels of POPs can be ingested by organisms in the bio-sphere. Given the increased levels of plastic pollution of the environment, this is an important concept in understanding the food web.
Read more about this topic: Polyvinyl Chloride
Famous quotes containing the words health and, health and/or safety:
“We have two kinds of “conference.” One is that to which the office boy refers when he tells the applicant for a job that Mr. Blevitch is “in conference.” This means that Mr. Blevitch is in good health and reading the paper, but otherwise unoccupied. The other type of “conference” is bona fide in so far as it implies that three or four men are talking together in one room, and don’t want to be disturbed.”
—Robert Benchley (1889–1945)
“Our young people are diseased with the theological problems of original sin, origin of evil, predestination, and the like. These never presented a practical difficulty to any man,—never darkened across any man’s road, who did not go out of his way to seek them. These are the soul’s mumps, and measles, and whooping- coughs, and those who have not caught them cannot describe their health or prescribe a cure. A simple mind will not know these enemies.”
—Ralph Waldo Emerson (1803–1882)
“Firm, united, let us be,
Rallying round our Liberty;
As a band of brothers joined,
Peace and safety we shall find.”
—Joseph Hopkinson (1770–1842)