Toxic effects, vinyl chloride

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 hazards of chemicals are commonly detected in the workplace first, because exposure levels there are higher than in the general environment. In addition, the exposed population is well known, which allows early detection of the association between deleterious health effects and the exposure. The toxic effects of some chemicals, such as mercury compounds and soot, have been known already for centuries. Already at the end of the eighteenth century, small boys who were employed to climb up the inside of chimneys to clean them suffered from a cancer of the scrotum due to exposure to soot. This was the first occupational cancer ever identified. In the viscose industry, exposure to carbon disulfide was already known to cause psychoses among exposed workers during the nineteenth century. As late as the 1970s, vinyl chloride was found to induce angiosarcoma of the liver, a tumor that was practically unknown in ocher instances. ... 

Most of the materials used in the manufacture of chemicals are poisonous, to some extent. The potential hazard will depend on the inherent toxicity of the material and the frequency and duration of any exposure. It is usual to distinguish between the short-term effects (acute) and the long-term effects (chronic). A highly toxic material that causes immediate injury, such as phosgene or chlorine, would be classified as a safety hazard. Whereas a material whose effect was only apparent after long exposure at low concentrations, for instance, carcinogenic materials, such as vinyl chloride, would be classified as industrial... 

Additive toxic effects, 25 213—214 Adducts, of vinyl chloride, 25 632 Adenine, 8 174. See also ADP entries Adenocard, molecular formula and structure, 5 98t... 

When exposures to chemical carcinogens have been high enough to cause noticeably large risks, there has usually been little doubt about the need to reduce the risks. It is well known, however, that cigarette smoking — one of the most serious public risks — has not been drastically reduced, e.g., Loeb et oL, 1984. In the case of vinyl chloride monomer, which is used to manufacture the millions of tons of plastic in use, no associated toxic effects were known 25 years ago, and no... 

The induction of unconsciousness may be the result of exposure to excessive concentrations of toxic solvents such as carbon tetrachloride or vinyl chloride, as occasionally occurs in industrial situations (solvent narcosis). Also, volatile and nonvolatile anesthetic drugs such as halothane and thiopental, respectively, cause the same physiological effect. The mechanism(s) underlying anesthesia is not fully understood, although various theories have been proposed. Many of these have centered on the correlation between certain physicochemical properties and anesthetic potency. Thus, the oil/water partition coefficient, the ability to reduce surface tension, and the ability to induce the formation of clathrate compounds with water are all correlated with anesthetic potency. It seems that each of these characteristics are all connected to hydrophobicity, and so the site of action may be a hydrophobic region in a membrane or protein. Thus, again, physicochemical properties determine biological activity. 

Vinyl chloride is a chemical used in the manufacture of plastics, which is carcinogenic and causes various toxic effects, including liver injury and damage to the bones and skin. Liver hemangiosarcomas are produced in animals and humans. Vinyl chloride undergoes metabolic activation by cytochrome P-450 to an epoxide, which may interact with DNA and form adducts (ethenodeoxyadenosine and ethenodeoxycytidine), which leads to mutations. These can be detected in white cells, and a mutant p21 ras protein can be detected in the serum of exposed workers. Also, reaction with GSH occurs. 

List the toxic effects of vinyl chloride. One of these shows an unusual dose-response relationship. Briefly describe and explain this. Name any toxic metabolites produced by metabolism of this compound. 

CA 86, 51210 (1977) [The toxic effect of PVC combstn products on the human organism was evaluated and the Toxic Threshold Level is reported as 0.3g of PVC products/M3 of air] 2) M. Bert et al, Reduction of Smoke Generation in Poly (Vinyl Chloride) Combustion , FireRes (4-5), 301-11 (1978) CA 90,72796 (1979) [The authors report that the most efficient (toxic) smoke suppressors for PVC are those which show catalytic activity in oxidation reactions, such as Cu, Fe, or V compds. These suppressors cause incandescence and complete combstn of the solid residue without excessive smoke prodn. They conclude that their efficiency is not very dependent on the anion bound to the metal, but may depend on the temp] 3) E A. Harrison, Toxicity of Vinyl... 

One of the most effective biocides currently available is 10,10 -oxybisphenoxarsine (22). It is supplied as a dilute solution in various plasticizers (to minimize toxicity problems) and is used exclusively as a preservative for flexibilized poly(vinyl chloride). It is very stable to heat and light and performs well for exterior applications. 

General term applied to effects of toxic substances to the liver Caused by exposure to vinyl chloride Characterized by deposition and buildup of fibrous collagen tissue that replace active liver cells... 

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 illustrate this point consider the production of lacquers for PVC films and sheeting. Such lacquers contain a PVC homopolymer or low-acetate vinyl chloride-vinyl acetate copolymer, poly(methyl methacrylate), a plasticizer and perhaps some stabilizers, dulling agents (such as silica), pigments, and so on. Methyl ethyl ketone (MEK) is the solvent of choice because it gives the best balance of low toxicity, volatility, and low cost. Any other solvent is effectively... 

The adverse effects of tetrachloroethylene are similar to those of carbon tetrachloride (CQ4), but less severe. Tetrachloroethylene is hepatotoxic and neurotoxic, but gastrointestinal disturbance is the only common adverse effect when it is used carefully. There is some risk of addiction to the inhaled vapor inhalation can result in vascular reactions, loss of consciousness, pulmonary edema, and fatal hepatic and renal damage. Alcohol and fatty foods increase absorption and hepatic toxicity. Exposure to tetrachloroethylene has been known to lead to vinyl chloride disease. Allergic reactions have not been reported. 

Chronic animal studies report increased mortality and weight loss, as well as effects on the liver, kidney, and CNS at levels as low as 1.3 mg kg day Animal studies have shown increased testicular damage as well as decreased male fertility in rats exposed to low levels of vinyl chloride for 12 months. In addition, some animal studies have shown decreased fetal weights and increased terata at maternally toxic inhalation exposure levels of vinyl chloride. Animal studies have also reported that inhaled vinyl chloride increases the incidence of angiosarcoma of the liver. 

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