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:
“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)
“Nothing in Nature’s sober found,
But an eternal health goes round.
Fill up the bowl, then, fill it high,
Fill all the glasses there—for why
Should every creature drink but I?
Why, man of morals, tell me why?”
—Abraham Cowley (1618–1667)
“There was only one catch and that was Catch-22, which specified that a concern for one’s own safety in the face of dangers that were real and immediate was the process of a rational mind.... Orr would be crazy to fly more missions and sane if he didn’t, but if he was sane he had to fly them. If he flew them he was crazy and didn’t have to; but if he didn’t want to he was sane and had to.”
—Joseph Heller (b. 1923)