Health and safety issues.
Because plastics are relatively inert, the final products do not normally present health hazards to the maker or user. However, some monomers used in the manufacture of plastics have been shown to cause cancer. Similarly, benzene, which is an important raw material for the synthesis of nylon, is a carcinogen. The problems involved in the manufacture of plastics parallel those of the chemical industry in general.
Most synthetic plastics are not environmentally degradable; unlike wood, paper, natural fibres, or even metal and glass, they do not rot or otherwise break down over time. (Some degradable plastics have been developed, but none has proved compatible with the conditions required for most waste landfills.) Thus, there is an environmental problem associated with the disposal of plastics. Recycling has emerged as the most practical method to deal with this problem, especially with products such as the polyethene terephlalate bottles used for carbonated drinks, where the process of recycling is fairly straightforward. More complex solutions are being developed for handling the commingled plastic scrap that constitutes a highly visible, albeit relatively small, part of the problem of solid waste disposal.
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