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:
“It is always singular, but encouraging, to meet with common sense in very old books, as the Heetopades of Veeshnoo Sarma; a playful wisdom which has eyes behind as well as before, and oversees itself. It asserts their health and independence of the experience of later times. This pledge of sanity cannot be spared in a book, that it sometimes pleasantly reflect upon itself.”
—Henry David Thoreau (1817–1862)
“Plants are the young of the world, vessels of health and vigor; but they grope ever upwards towards consciousness; the trees are imperfect men, and seem to bemoan their imprisonment, rooted in the ground.”
—Ralph Waldo Emerson (1803–1882)
“There is always safety in valor.”
—Ralph Waldo Emerson (1803–1882)