Document nmQnN6nY5MEM14VbJ08j8JL41

R&S 027478 DOW POSITION STATEMENT - VINYL CHLORIDE There is much work going on relative to assessing the toxicity of vinyl chloride monomer (VCM) and to interpreting the data available into appropriate work practices which will permit the material to be manufactured, handled and used with a high degree of safety. The most pertinent data available may be briefly summarized as follows: 1) Humans who were exposed to VCM years ago have developed cancer of the liver (angiosarcoma). The intensity and duration of the exposures they received are unknown except that they are believed to be high. 2) Examination of all the medical records available on persons who have worked with vinyl chloride at Dow have revealed no cases of angiosarcoma of the liver. Exposures that occurred prior to about 1960 in the Midland facility were in the range of 200-300 ppm on a time-weighted average basifs with peaks of short duration (minutes) ranging up to 1000-2000 ppm on a few particular jobs where documenta tion is available. Since 1960, when continuous monitoring was initiated along with a 50 ppm guideline, exposures (TWA's) with one exception have been below 50 ppm with rare short excursions into the 1000-2000 ppm range. The R&S 027479 2- - one exception is a location where concentrations range from 100 to 150 ppm and respiratory protection is required. In recent years personnel monitoring at outdoor plants in other locations has revealed TWA exposures to be controlled within the existing Dow guideline. 3) The toxicological studies on animals in the Italian laboratories of Professor's Viola and Maltoni have revealed cancer of the liver (angiosarcomas) and other malignancies in rats exposed four hours/day, five days/week for extended periods of time, to VCM concentrations of 250 ppm and higher but not at 50 ppm. Mice exposed for 35 weeks to 2500 ppm have developed angiosarcomas of the liver, mammary carcinomas (possibly too few to be signifi cant) and adenocarcinomas of the lung. At concentrations of 500 and 250 ppm, mice have developed adenocarcinomas of the lung but at.50 ppm no cancers have been observed. Intermediate concentrations are being studied. 4) Toxicological studies on animals sponsored by American industry through the MCA are being conducted at Industrial Bio-Test Laboratories (IBT). In these studies, rats, hamsters, and mice have been exposed 7 hours/day, 5 days/week for up to 7 months at concentrations of 2500, 200, and 50 ppm. R&S 027480 -3- No tumors have been observed among the rats or hamsters, but tumors have been observed in the livers (angiosarcomas), lungs, and subcutaneous tissue of the mice at all three levels of exposure. The subcutaneous tumors tentatively are considered to have originated from mammary tissue or Zymbal's gland of the ear canal. The incidence of tumors appears to be dose-related. The finding of tumors in mice exposed to SO ppm VCM has increased the political pressure in Washington for a downward revision of the limits as specified in OSHA's Emergency Temporary Standard for Exposure to Vinyl Chloride published in the Federal Register, Friday, April 5, 1974, Vol. 39, No. 67, pg 12342-4. We also feel that it is desirable to increase the margin of safety and propose the following guidelines as work practices. Area monitoring. Work areas in which VCM may reasonably be expected to exist should be monitored continuously using an automatic sampler, analyzer and printout, if feasible. Other detection devices may also be used for spot or routine repeated sampling as needed. An analytical sensitivity to at least 5 ppm must be required. If monitors show the concentration in the work area to exceed 25 ppm, all persons must don appropriate respiratory protection if their exposure is expected to last more than 10 minutes. -4- If monitors detect a concentration of 50 ppm (or more), they shall sound an alert which requires all persons to evacuate the area and put on appropriate respiratory equipment before reentering the area. If some event occurs which suggests that excessive concentra tions may exist, an alert should be sounded and action as described immediately above must be taken. % If work must be done in areas which consistently approach or exceed 25 ppm as determined by sound industrial hygiene studies workers shall always wear appropriate respiratory protection when entering such an area. These areas should be well identified. Personnel monitoring. Personnel monitoring should be conducted so that an evaluation of the actual exposure of individuals by inhalation can be calculated; i.e. the samples must be taken from the breathing zone of the person. A person wearing appropriate respiratory protection in a contaminated area as determined by area monitoring may not be exposed at all and this must be taken into account in the assessment of the individual's total exposure as determined by proper industrial hygiene practices. ft&S 027481 % -5Recommended Dow guidelines for vinyl chloride. The timeweighted average exposure (TWA) for an 8-hour day should not exceed 10 ppm for any individual and the ceiling for short exposures should not exceed 25 ppm. V. K. 5/7/74 R&S 027482