Chemistry

Chemical Properties & Production

Vinyl Chloride Monomer (VCM) is a highly volatile molecule that exists as a gas at Standard Temperature and Pressure; for this reason, occupational exposure to VCM occurs primarily through inhalation. Many vinyl workers are surprised to learn that humans are unable to detect the smell of VCM until it is present at levels at least thousands of times higher than the one part per million (1ppm) permissible exposure limit (PEL) established by OSHA in it's 1974 standard. (VCMs "odor threshold" is most often estimated at 3,000 to 4,000 ppm.) The smell of VCM is universally described as sweet and not unpleasant.

VCM is manufactured by the relatively simple process of heating ethylene dichloride (EDC) to around 700F in the presence of oxygen. VCM is manufactured in a relatively small number of plants that are almost entirely located along the Gulf coast in Texas and Louisiana. VCM is used almost exclusively in the manufacture of various types of polyvinyl chloride (PVC) resins at PVC resin plants located across the United States, but again, primarily in Texas and Louisiana using, again, a relatively simple manufacturing process called polymerization.

VCM is charged to large polymerization reactors that are often referred to as "polys" or PVC "kettles." Since the polymerization process never consumes all of the available VCM, varying amounts of VCM remain trapped in every form of PVC resin and in every finished product fabricated from PVC resins. As a result, this residual vinyl chloride monomer (RVCM) is present in varying quantities in all raw PVC resin and in all finished PVC products until it is liberated into the atmosphere by "off-gassing" or migrates into food, drink, or other substances stored in containers made of PVC as well as various types of food wraps, etc. The potential adverse health effects associated with consumer product exposures are predictable but, because of the relatively low levels involved and the ubiquity of such exposures, difficult or impossible to demonstrate empirically in human beings. However, given animal studies and biological considerations, RVCM almost certainly poses a significant risk to human beings even at exceedingly low levels, notwithstanding industry propaganda to the contrary. However, the potential health risks posed by PVC products is not at all limited even to the millions of workers involved in fabricating PVC products, but extends to everyone who is exposed to vinyl products, meaning virtually everyone.

From the PVC plant, raw PVC resin is bagged and shipped to a large number, perhaps hundreds, of compounding facilities where the raw PVC resin is compounded with other chemicals. Most resin, however, is shipped by rail and tank truck to thousands of PVC fabrication plants where fabrication workers melt or mold the PVC resin and process it to make consumer goods. In the course of product fabrication, millions of American workers are occupationally exposed to significant levels of vinyl chloride although the vinyl industry would have us believe that only those workers directly involved in the manufacture of VCM or PVC resin are at risk for occupational diseases caused by vinyl chloride exposure. Even the limited studies that have been conducted demonstrate a clear occupational health hazard for these "downstream" vinyl workers involved in melting, molding, extruding, and calendaring PVC into "thousands of useful finished PVC products."

Toxic Effects

The independent scientific community has recognized VCM as a multi-potential carcinogen for almost thirty years and it is recognized as a potent cause of a wide variety of cancers arising in various organs of the body, both in humans and in animals. These cancers are not at all limited to vinyl chloride's "signal neoplasm," angiosarcoma of the liver, whose very existence in a given population strongly implies a larger occupational cancer risk caused by vinyl chloride. The most commonly recognized vinyl chloride related cancers include primary non-angiosarcoma liver cancer, primary brain cancer, lung cancer, lymphoma, and cancers of the blood and blood-forming organs. Perhaps surprisingly or, considering evidence developed in vinyl chloride litigation, perhaps not so surprisingly, the most commonly unappreciated adverse health effects associated with vinyl chloride exposure do not involve cancer. The true nature and extent of these non-malignant diseases has been the subject of an industry wide cover-up since at least the 1960s. The concealment of VCM's toxicity goes back even further. Although the vinyl industry has been largely successful in its efforts to declare the non-malignant diseases caused by vinyl chloride a more or less moot point, their having been all but completely eliminated by reduced exposure levels supposedly common in these modern times, the truth is that systemic non-malignant disease is very likely still an enormous problem and is certainly enormously undocumented and unappreciated by the general public and even most public health professionals. The non-malignant diseases caused by vinyl chloride exposure are systemic and serious, often resulting in a systemic sclerosis of the body as a whole, and are known outside the United States as "vinyl chloride disease." However, these non-malignant diseases are probably often obscured by their non-specific nature (Raynauds syndrome, scleroderma, acroosteolysis, etc.) with alternate etiologies, including such common ailments as autoimmune disease, arthritis, dermatitis, idiopathic sclerosis, and even carpel-tunnel syndrome. Also, because the non-malignant diseases are insidious and not so often a direct cause of death in afflicted persons, and hence undetected by even well conducted mortality studies, VCMs role in causing these diseases remains unappreciated. Morbidity studies that would normally be necessary to detect such insidious and chronic diseases are quite rare in comparison with mortality studies. However the limited studies that are available, for example a study of former workers at a "modern" Vinatex PVC plant in Chesterfield England that began operations only in 1969 have shown an enormous prevalence of non-malignant diseases (diseases that the industry long ago declared to be all but extinct) even in workers whose first exposures occurred after 1974. Neither the chronic effects of vinyl chloride at relatively low dosages, nor the adverse health effects resulting from a single or limited number of high-level exposures (such as exposures resulting form accidental spills, emergency releases, etc.) is completely known in part as a result of the vinyl industry's deliberate abandonment of research efforts in these areas. Once the initial "vinyl chloride scare" died out following the sensational public report of angiosarcomas that occurred in workers at a BFG PVC plant in Louisville Kentucky in 1974, industry began to limit the scope of disease attributable to VCM exposure. Hopefully avenues of research long ago abandoned by industry will one day be again taken up by independent scientists as a result of an increasing awareness of the vinyl industry's abrogation of it's commitments and other responsibilities to investigate the nature and extent of the diseases caused by vinyl chloride.
[Some Known VC Related Disease]