Document gaLBoMd08XbLbXMR5YJpX3g19

May 21. 1973 INFORMATION ON VINYL CHLORIDE TO BE PRESENTED ORALLY TO NIOSH I. Description of the Vinyl Chloride and Polyvinyl Chloride Industry Vinyl chloride is a commodity used in very large quantities to make polyvinyl chloride resins (polymer and copolymer}. The following estimated figures for 1972 illustrate the tremendous inportance of this industry which has operated for 35 years in the United States and 40 years in Europe. U.S. Production U.S. Capacity World Production Vinyl Chloride 5.2 billion lbs (0.5 exported) 5.9 billion lbs 22 billion lbs Polyvinyl Chloride 4.4 billion lbs Annual growth last 5 years 14% Projected annual growth, U.S. 114 U.S. Plants 14 37 (23 companies) U.S. Workers World Workers 15 0.0 10,000 5000 Virtually all (>99) vinyl chloride is used in production of tyfro K> polyvinyl chloride and other polymers. It is difficult to estimate the number of workers employed in converting, molding, and fabricating these polymers but it is of the order of 10's of thousands, working in thousands of plants. It has been estimated that the wholesale value of fabricated products is over $3 billion. Almost all of the vinyl chloride and polyvinyl chloride producers in the U.S. are participants in the MCA Technical Task Group on Vinyl Chloride Research. Over 954 of the PLAINTIFFS EXHIBIT 12866 U.S. vinyl chloride capacity and 85%'of the pvc capacity are represented by the following 20 companies today. Air Products Allied Chemical Borden Chemical BP Industries (British) Conoco Diamond Shamrock Dow Ethyl Exxon Firestone Goodrich Goodyear Monsanto Olin PPG Shell Stauffer Tenneeo Union Carbide Uniroyal II. Summary of Toxicity Studies on Vinyl Chloride Monomer A. Published Information on VCM URL 2 2 8 6 7 Vinyl chloride monomer was for many years considered to be very low in toxicity, both from single and repeated exposure. Because of its volatility, inhalation was considered the only important route of exposure for workmen. Ihe high flammability of VCM has been considered to be a more serious hazard than inhalation. From the earliest lists until 1962, the American Conference of Governmental Industrial Hygienists (ACGIH) recommended that the time-weighted average long-term 7-8 hour daily exposure of workmen not exceed 500 ppm v/v mg/m^). This recommendation was based on single exposure studies on animals and on human experience. Recommended time- weighted average concentrations are published by the ACGIH in an annual list of "Threshold Limit Values" (TLV). A TLV was considered by this group to "represent conditions under which it is believed that nearly all workers may be I repeatedly exposed day after day, without adverse effect." In 1963 the ACGIH modified their Recommendation go that 500 ppm was to be a maximum concentration (or ceiling) rather than a time-weighted average. This change was in part due to the publication by Torkelson, Oyen, and Rowe (American Industrial Hygiene Association Journal Vol. 22, p 354, 1961) of the results of six-months repeated /&. inhalation studies on laboratory, animhls. These authors reported ssLight reversible( liver RajSSfc in rats exposed 7-hours per day tc^jS^ppm and recommended that the time- i weighted average exposure of workers not exceed 50 ppm. However, this recommendation was not considered appropriate by Lester, .Greenberg, and Adams - (jjaid. Vol. 24, p 265, 1963) jt..... ilder siinj ui>y to have resulted in . rats which they had repeatedly exposed to<ffilppm v/v. /n **C- **,"9 19 About 1963-1964 reports appeared in the European literature describing pain and tenderness in the fingers of polyvinyl chloride workers. X-ray examination showed that the bones of the hand were dissolving. This condition known as acroosteolysis was also investigated by American vinyl and polyvinyl chloride companies and similar disease was found in workers who, cleaned polymerization vessels. The epidemiological data from this investigation was published in January 1971. (Archives of Environmental Health, Vol. 22, pp 61-91, 1971). This epidemiological study was directed at workers currently employed by the companies. In May 1970, Dr. P. Luigi Viola, an Italian physician, reported in Houston that he had attempted to create a bone condition in rats similar to human acroosteolysis. (Tenth Inti. Cancer Congress, Houston, Texas, May 22-29, 1970). Dr. Viola observed tumors in the ear canals of rats exposed to 30,000 ppm (3%) vinyl chloride vapor 4 hours per day for 12 months. Viola also reported tumors in the lungs and bones of these rats but these later tumors are of questionable significance. URL 22868 These data were subsequently published (Viola, P. L., Bigotti, A., and Caputo, A., Cancer Research 31, 516-522, May 1971). In 1970 the ACGIH proposed reduction of their recommended TLV to a time-weighted average of 200 ppm primarily on the basis of work reported by Xramer and Mutchler at a 1968 Gordon Research Conference on Toxicology`and subsequently published in January 1972 (American Industrial Hygiene Association Journal, Vol. 33, p 20, 1972). The authors reported evidence of clinical findings in workers exposed to a time-weighted average concentration of 300 ppm VCM for many years. In 1972 the ACGIH took vinyl chloride from the list of Intended Changes and changed the value in their regular list to 200 ppm. This value remains the recommended value in the 1973 list. A copy of the Documentation for the ACGIH TLV for vinyl chloride as published in 1971 is attached. * In order to get more details of Dr. Viola's experiments, including additional unpublished studies and observations that he might have compiled, he was invited by the Manu facturing Chemists Association to visit Washington and discuss his findings with MCA's Occupational Health Commit tee. On May 5 and 6, 1971, he discussed data published in 1971 and referred to other studies completed and underway. Dr. Viola was extremely vague and evasive in giving details. He did report that his vinyl chloride was quite impure and claimed to have seen tumors in rats exposed to 5000 ppm. He thought 2500 ppm would be without such an effect. He produced no data and refused to give details. He'claimed * he would not be concerned about workers exposed to less than 500 ppm. We are not aware of any further publications by Dr. Viola on this subject. URL 2 2 8 6 9