Document OJKBRN6o5n07RR7DeDkp4VdaQ

A. E. ArdU / Richard Henderson M University of Michigan Study A*oo*t, Mui, Nev Havan, Conn. Septaaber IS, 1969 cofy to Fila f'o'^ Enclosed are copies of three pages from the University of Michigan report. In addition to the seven positive and two questionable mentioned in this report* there are also reports of positives from France and Belgium. Note the recommendation that exposure to vinyl Chloride monomer should be kept below $0 parte per million instead of $00 parts per million* which is the current Threshold Limit Value of the American Conference of Governmental Industrial Hygienists. KHiaph Enel.-pages 101-103. i Richard Henderson why me thi* eoFYt ir you muit mitain it, bpccify a pbfimitb mktknyiom pcmiodi on via*. OLI 2375 OTMBII. or elsewhere, followed by healing after removal from the job but with per sistent Raynaud's phenomenon. 1. Reactor Scraping This Job appears to be the greatest single factor in the precipitation of AOL. In the overwhelming majority of cases, a history of work In this Job can be found. In some few cases outside this study, AOL has been seen to oc cur In maintenance mechanics. The cleaning of lines from the reactor tanks may afford these workers occasional exposures qualitatively similar to that of reactor cleaners* 2. Compounding Operations Ho definitive cases of AOL were found In operations Involving compounding or fabrication of the finished polymer. Neither was there undue Raynaud's phenomenon occurrence in such plants. The relatively small population Involved (l.e., 357 Individuals) does not prove, of course, that the disease never occurs In this operation. The one questionable x-ray (Ox Cat. 4) seen in this population Is not unexpected in view of the conmon occurrence of such border line x-rays In the control population. F. MATERIAL EXPOSURE AND ACL i 1 1. Despite cosputer assisted comparison, no one compound or class of ccopounds clearly or exclusively was associated with the plants having AOL In cosparlson to plants without AOL. 1 I 2. As regards Raynaud's phenomenon, there is a possibility that exposure to vinyl chloride per se may precipitate a response. While It Is understood i] that the exposure to vinyl chloride In such unique operations Is minimal, nevertheless, the rather unexpected higher incidence of Raynaud's phenomenon In Plant Q is noteworthy. If this turns out to be the case, the IxpUcatlcns for the etiology of ] AOL are obvious. Accordingly a close surveillance of VC monomer production population nay prove valuable. ] G. WORK PRACTICES AND AOL J 1. Recovery Phase The use of a short period far recovering unreacted monomer from the poly mer might lead to more residual monomer In the reactor (e.g.. In voids of FVC 101 OLI 2376 1Tr * residue on reactor walls). A study of the temperature and time characteristics of the recovery phase in several plantB failed to show differ nces In practices between plants with AQL and thos without. * 2. Air Flush of Beactor Before Entry of Cleaner While operating procedures have been established by plant supervision, it appears that these are being shortcut by hourly employees resulting in In' creased potential for exposure. 5. Beactor Cleaning Procedures Hand scraping of reactors has been practiced In ell plants except one that started operation In 1966 and which has always used solvent cleaning. Among the seven plants with AOL, all band scraped the reactors, generally after every hatch, though one of these started using water jets in 1965 and another cleaned a portion of the reactors with water jets from 1962. Among the 17 plants without AOL, only 10 band scraped the reactors after evexy batch and one of these changed to solvent cleaning in 1965. Others manually cleaned reactors every 2 to 10 hatches. The plant that started operatian in 1966 with solvent cleaning has bad no cases. > In the two plants with questionable cases, one hand scraped the reactors after every hatch and one after "several" cycles. The latter utilized solvent cleaning intermittently far a portion of the reactors in 1966. Size differences in plsnt populations between the "positive" and "negative" plants reduce the validity of meaningful cosperlsons between the two groups as . related to cleaning aethoda. Use of high pressure water jets and solvents for reactor cleaning greatly reduced the time that workers were inside the reactors following discharge of the batch and also their contact with materials remaining in the reactor. * H. CONTROL MEASURES IX FRZVHfTIOT CT ACROOSTEOLY8IS In suggesting control methods, it would seem in order to reduce exposure to suspect materials even though the identification of them as the causative agents is not conclusive. Decrease in the time spent scraping reactors could be acccnpllshed by mare extensive utilization of high pressure water or sol vents In cleaning procedures. The severity of exposure of reactor cleaners to vinyl chloride and also of personnel on the charging floor should he kept at a minimum, desirably below 50 parts per million as suggested by Torkelson et al.9 102 OLI 2377 t 1 * ! i i r t r l ib ! f 1 i 1 1 | 11 f rather than merely below the current threshold limit valu of 500 parts per million. To assure that atmospheric concentrations are below this level, air analysis Instruments of adequate sensitivity should be used. The flanmsble vapor detector at most of the plants gives a positive reading only down to 100 to 800 parts per million of vinyl chloride. A more sensitive instrument of this type is conmerclally available that reads to a tenth of these levels. Also a portable gas chromatograph has recently become commercially available that has even greater sensitivity. Both these Instruments give Immediate readings of the concentration present. The current practice of venting the reactors by means of a portable blow r placed on the charging floor with the vinyl chloride laden air from the reac tor being discharged Into the general charging roam atmosphere may result In excessive vinyl chloride concentrations In this area occupied by the reactor operators and others. Since the odor threshold is 4000 parts per million, freedom from odor does not assure safe concentration. Certainly the concen tration varies greatly depending on the enclosure, general ventilation, and the number of reactors being vented during the day. Air analysis using ade quately sensitive methods should be conducted In these areas. If vapor con centrations at locations where personnel la exposed are above 50 parts per million for any appreciable duration, consideration should be given to provi sion of an exhaust system to remove residual vinyl chloride from the reactor to the outside of the building or to a vapor recovery system. 105 v OLI 2378