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:
“Medication alone is not to be relied on. In one half the cases medicine is not needed, or is worse than useless. Obedience to spiritual and physical laws—hygeine [sic] of the body, and hygeine of the spirit—is the surest warrant for health and happiness.”
—Harriot K. Hunt (1805–1875)
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—Ruth Davidson Bell. Ourselves and Our Children, by Boston Women’s Health Book Collective, ch. 3 (1978)
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—Lewis P. Lipsitt (20th century)