Vinyl chloride toxic product from

The commercial and household products containing polyvinyl chloride are generally regarded as posing no threat to human health. However, a number of questions have been raised about possible health hazards and risks to the environment as a result of the process by which polyvinyl chloride is made, some of its applications, and its eventually disposal. For example, polyvinyl chloride is made from vinyl chloride, which itself is toxic and a carcinogen. People who work with vinyl chloride in production facilities are at risk for developing a form of liver cancer that may be related to exposure to vinyl chloride. Vinyl chloride, in turn, is made from chloride, a very toxic gas that poses health risks to people who work with it. 

Most toxicity problems associated with the finished product arise from the nature of the additives and seldom from the polymer. Mention should, however, be made of poly(vinyl carbazole) and the polychloroacrylates which, when monomer is present, can cause unpleasant effects, whilst in the 1970s there arose considerable discussion on possible links between vinyl chloride and a rare form of cancer known as angiosarcoma of the liver. 

The environmental impact of PVC is discussed with reference to the toxicity of vinyl chloride, plasticisers and heavy metal stabilisers, the formation of dioxins and acid rain resulting from the incineration of PVC waste, and plasticiser migration from PVC products. A brief examination is also made of the recyclability of PVC. 18 refs. 

Vinyl chloride (VC) is the monomer from which the common polymer, polyvinyl chloride, is produced. Hence, VC is produced on a very large scale. Not surprisingly, occasional releases of the rather toxic VC to the environment occur. What initial biodegradation product would you expect from VC if it were released into an oxic environment ... 

As a second example, there is a wide variety of breakdown products and oligomeric products that may be formed from the reactive monomers that are the building blocks of plastics. For plastics, the general assumption has been that any side-reaction products and breakdown products are likely to be significantly less toxic than the monomers, and so restricting the migration of the monomer was accepted as an indirect way to limit any hazard from the oligomers also. Whilst this approach is probably acceptable for addition polymers, such as those made from the unsaturated monomers vinyl chloride, butadiene and acrylonitrile where the unsaturated monomer is far more noxious than their products, the validity of this means of indirect control is questionable for condensation polymers such as polyesters and for polyethers formed from epoxide monomers. 

Acetylene (Figure 13.1) is widely used as a chemical raw material and fuel for oxyacetylene torches. It was once the principal raw material for the manufacture of vinyl chloride (see reaction 13.2.4), but other synthetic routes are now used. Acetylene is a colorless gas with an odor resembling garlic. Though not notably toxic, it acts as an asphyxiant and narcotic and has been used for anesthesia. Exposure can cause headache, dizziness, and gastric disturbances. Some adverse effects from exposure to acetylene may be due to the presence of impurities in the commercial product. 

To do this, a highly active, nonselective catalyst is required. This is in direct contrast to almost all industrial oxidation reactions where selectivity for partially oxidized products is essential. Another consideration for removal of trace contaminants is that, if the oxidation is incomplete, compounds more toxic than the trace contaminant may be formed (e.g., formation of phosgene from incomplete oxidation of vinyl chloride vapors). 

We have examined a number of materials in terms of toxic gas evolution during pyrolysis or combustion. For example, the products from fibreglass insulations included isocyanic acid and hydrogen cyanide, while the support backing and adhesive of a made-up panel produced acetic acid, acetaldehyde and vinyl chloride as well. The effect of a fire in a confined space such as a surface ship or submarine can be imagined. The products come from thermal decomposition of polymer coatings etc, and while the experimental conditions may not duplicate those of a fire, the information is very useful. 

The most obvious toxic product, that could be formed from vinyl chloride, is chlorooxirane, due to oxidation of vinyl chloride by a monooxygenase. 

If a company is in the business of making and selling products such as acetic acid, vinyl chloride, propylene oxide, or other chemicals and has plans to stay in business and to expand its facilities to serve growing markets, it at least must have economically competitive processes. Today this means being competitive with not only any new processes developed in the United States, but also with any new process technology developed in Western Europe, Japan, and Russia—for the chemical industry is a worldwide industry. This is readily apparent from the data in Tables 1.10, 1.11, and 1.12, which describe the sales for the largest chemical producers in the United States, Western Europe, and Japan, respectively. Further, the processes that are operative must be environmentally compatible—all toxic or carcinogenic by-products or waste must be contained and disposed of harmlessly. Even a relatively innocuous by-product such as salt must be disposed of so as not to intrude on the environment. 

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