Document 4ayzDpg61o9N72dJr17095mOa

NATURE OF THE HEALTH HAZARD FROM CHRONIC EXPOSURE TO VINYL CHLORIDE INCLUDING SPECIFICALLY THE CARCINOGENIC HAZARD This part of your training is intended to cover the Nature of the Health Hazard from Chronic Exposure to Vinyl Chloride Including Specifically the Carcinogenic Hazard. Since those of us who are hand! ing the training program are not medical men, this part will be read to you. To be sure it is adequately covered, part of what I will read was abstracted from the preamble to the OSHA standard. r-` r'ij ' - Sa.'1 >' X-i ^ ' ' : ` ,* ' 'Vr , '* - -m' Jr"t i : ' iT'O'-r! V Vinyl chloride has been used in making FVC Resin for approximately forty years. Until recently it was thought to have no long lasting effect on the health of those exposed. Its anesthetic properti s were well known, and in the work place there were two main concerns. One was anesthetization or asphyziation. At concentrations in the v range of 25000 PPM dizziness occurs and with continued exposur above that concentration the exposed person may lose consciousn esJ7, There was always the danger to consider that a lone individual try-7 jpg to control a serious leak might be overcome by the vapor and if 17 * not/found,-lose his life. The second concern was the danger ^of fire or explosion if an ignition source occurred coincident with,fstfcon- centration of VCM vapor in the explosive range of approximately to 2756. Plant design and safe operating procedures were planned around those two dangers. , %>;. ^ MV* ' . ' 1 '. ^ * ' ' .J . . t . , -5: More recently the danger of contracting angiosarcoma of the liver : from long expostire to VCM has been discovered and this is th pri- / ^mary reason for OSHA VCM Standard 1910.95q about which you have heard so much lately. ; This is the reason for the use of respiratory; equipment, the plant modifications taking place and planned, th medical surveillance program, and it is the subject of this current training program. .i * V: ; -t. _ 1^7`The training program as outlined by OSHA requires that the car cinogenic,hazard of chronic exposure to VCM be explained to each eB^loyee^lAc'^ally;, this is inherent in our entire coutpliance pro-. /gram.S^oh^^vlbieard why the respirators are required and will ;; ; hear t^a?againi^However, to carefully comply with this require-- ^ei^ I will read to you this abstract of part ;:. standard titled Findings Regarding Carci- , ^6genicity#Exposure Levels and Feasibility. Some additional 1- explanatory comments have been inserted for clarity where a state- 7: ment.would not have meaning or might be misleading without r ference. to the res.i^ -pf the document. (Bracketed sections are'the add d . comments. '* " , - a- ` '. ',1 t' z?.- `'-is r.5 1 'i- r-v i" . . . r .r-'' - t 7: . 's : - ;: -;' 'W?- , -- frt.i * 1 ;; a'.-t ------ -i ^ Vv-i; ' OCC ($155 's^^. .' ';?. " ' ; 2- - y9jVtijj'vy ?. - - i 'V*1.., ' rr'te-x- A. bindings Regarding Carcinogenicity, Exposure Levels and -, Feasibility. " .1 Carcinogenicity of vinyl chloride. The carcinogenicity oi vinyl chloride for three animal species (rat, mouse, hamster) has heen documented on the record by studies of Maltoni and Bio-Test Laboratories. QMaltoni as you may already know is an Italian investigator who has been testing the effects of VCM on animals for several years^l Moreover, Maltoni's investigations have demonstrated a dose-dependent relationship for induction of tumors (Cfchat is^ more tumors occur at higher exposure levels), in cluding angiosarcoma of the liver, in rats. The inv stigations of Industrial Bio-Test Laboratories have demon strated a similar relationship for both rats and mic . These investigators have induced angiosarcoma of the liver in rats and mice at exposure concentrations of 50 PPM, and in hamsters at higher concentrations of exposure. Addi tional tumors involving other organs, including the kidneys, lungs, and skin of exposed animals, were also observed .' . in frequencies in excess of control animals. ' ...rfV-. According to the 1970 report by the Surgeon General's Ad- '\r v*. : ,f--vV.- '* i Hoc Committee on the Evaluation of Low Levels of Environ mental Chemical Carcinogens, the finding of cancer in. two V or more animal species may extrapolated to indicat 'a'".'''' carcinogenic hazard to humans. Here, such a finding was / made in three species that were exposed to VC by inhala tion--a route comparable to employee exposure. In addition, , there were at least 15 confirmed cases of angiosarcoma y :5 the liver among employees exposed to VC, a significant -number in view of the rarity of this cancer in the U.S. --T - ' adult male population (testimony of Dr. Marcus Key, ^-of NIOSH, at the rulemaking hearing). [A number .;:-R`9sfeiaddliti<mal cases-were discovered since this report v-&s^'^;%' '^was:.joade.',:- Ity best information is that as of April 1, 1975 A-i0^'ckBea'haye been discovered in this country. This" v investigation covered physical examinations of current .*ygvv-;''workers,:;examinations of autopsy records and slides of: " . ^r'^^Qeaa<e4*^dividual8 who at one time worked with vinyl - d health histories of current and past workersTT , it is concluded that VC must be regard d as ` carcinogen, and the probable causal agent of-". ^losarcoma of the;liver, and that exposure of employe syr;. , ^YC:must.-be controlled. . V' EXpostire iimits.Upon finding that exposure of employees r<f-- -3- 2. Exposure limits (continued), stances cannot be scien tifically determined. Several witnesses and persons who submitted comments have taken a contrary view and have suggested that man is 1 ss sensitive to biologic aberrations induced by vinyl chloride exposure than experimental animals. Proponents of this position have argued that if humans were as sensitive as rodents, an "epidemic" of cancer resulting from VO ex posures should have already been discovered among employees. They also argue that the employees in whom have been observed are those who have considerable employment ex perience as polymerization reactor cleaners. Because it is generally agreed that reactor cleaning involved high exposures to vinyl chloride in years past, it is argued that the lower levels currently found in the workplac have not induced cancer and are therefore safe. W [OSHAj, reject this argument. v ''f -,v ' . *f ::. '* rr ,.^ V , $L,~ The fact that approximately three-quarters of those employ es 7,v' v.-r'- with the longest exposure to VC (greater than 20 y ars sine v',. initial exposure) have not yet been located, makes it, im- possible to_determine the actual number of affected m- , ployeeees. [This statement by OSHA was made in September, ,1-n9r7TM4. . 33^ continued investigation has discovered the ad<diittiional cases mentioned earlier. Whether more will V; - ' be discovered and how many is, of course, not known at this timeTJ The cases of liver tumors observed to date . have an average latency period, since initial exposur , x. of^approximately 20 years. If it is assumed that induction -`W'bjt^, v. angiosarcoma is a dose-related phenomenon, and if m- 1ipls?altlocrgyeeersdoesnegsagoedf in cleaning reactors did, in fact, ~ receive vinyl chloride, it would be expected that 1^4 diich tumors would be observed earlier for this employ e . population. For this reason, the significance of presumed flower doses 'cannot bfe accurately assessed until a long r passed, as a longer induction period . , . v';. ' - batiaticn: of exposure to chemical carcinogens and induction "Icancej^rare not necessary synchronous events. B caus hysiologic complexities involved with carcinogenesis, t [UCtiontof tumors does not occur in all employees with ; lar^+exposure histories. For example, Dr* Schnelderman; tfie^Tational Cancer Institute emphasized during his -:-f. ^imony that only about a fifth of longer-term heavy ,,..L-f fsmokers develop lung cancer. Accordingly, the indiistry^^,;; .^.|$onitiuition'`that exposure levels have been dramatically ^l^^educed since the 1940`s is not reliable evidence that a;v"' p^PDWrent levels of exposure are safe. QPhe current level ^ erred' to in this case was the 50 PPM limit recommended v. ;|^-;"|^industry3 - : ' ` OCC  2. Exposure limits (continued). Some industry spokesmen also suggested that the apparent nonrandom distribution of observed cancer in employe s may indicate an exposure threshold for tumor induction, based on variations in the workplace design or practice and resultant employee exposures (testimony and questioning by Tenneco Chemicals, Inc.). It has also been emphasized that in only 3 of 8 polymerization plants where employees have been exposed to VC for more than 20 years have any employees developed angiosarcoma of the liver. This argument is very similar to that raised concerning vari ability of past employee exposure. Although geographic and workpractice differences may ultimately be demonstrated to be factors in distribution of angiosarcoma, sufficient information is unavailable to exclude from consideration of risk those employees in workplaces for which cas s of angiosarcoma have not been observed. It has also been suggested that the absence of cancer in 1 a population of 333 Dow Chemical Company polymerization employees monitored over a period of 7 years, indicates that exposure to vinyl chloride at concentrations of less ; V than 200 EPM is safe. (See study by Dr. Cook, submitted , .u-1 at the hearing by Dow Chemical Company.) However, the > ' group surveyed did not include all workers who had'been exposed, and the missing employees included many who had j;; 1 v the longer term (over 20 years; exposures. Moreover, the statistically insignificant size of the sample population :decreases the possibility that tumors would be observed. /V' i . -v* , *' < , i./ A numiber of witnesses: representing employers have str seed *that there is no evidence of cancer, either in employees 'or experimental animals, at exposure concentrations of VC dS": T.less than 50 PPM. (See e.g., testimony of Firestone, Tenneco Chemicals.) ~ The conclusion of these witnesses was OCC 0758. -.--35& -5- il Wepust read parts of the explanation of the carcinogenic hazard from the OSHA standard. If you have any questions I will try to answer them if I can. However, as I said, I have no medical background so if I can't answer your questions, I will make a note of them and get answers for you if answers are available.