Document mbygyznEDXgXean8V2EBa8EMZ

Stechnical week European Chemical Nown. Mv .'4 tu/4 CIA argues case against zero VCM exposure limits aitt a> npress Kbrruie>fKinng hheMld tlaasctt wwemeIkt iinn rpvennretrtraattiinonn of PVC in to a wide range London on vinyl chloride (VCM) toxi of market applications, as a major city the UK Chemical Industries Asso industrial material where alternatives ciation (CIA)'s vinyl chloride committee are not available in the quantities nor stressed that the PVC industry would in most cases with the properties stop dead if society demanded zero required, the CIA stated. exposures to VCM in the production, The four UK producers of PVC are fabrication and use of PVC to elimin so far spending over 4m. this year to ate the risk of industrial injuries. reduce the maximum possible atmo The vinyl chloride committee, which spheric concentration of VC^I exposure was set up about three months ago. to plant operatives to 25 ppm hv has as its terms of reference, "to volume, from the existing legal limit enquire into the nature and extent of of VCM exposure of 220 ppm. the hazard to health of vinyl chloride, Currently, 12 cases of angiosarcoma whether in the free state or as a con of the Uver (a rare liver cancer) have stituent of polymerized material. been discovered in the USA, one in the Secondly, to establish in collaboration UK, and around five in continental with expert bodies both in the UK Europe. These diagnoses (two cases are TiM t: UK uoo at PVC In ItlS still surviving) have occurred over a ten- Application Tonnagt hm4 Main aaaa Martlet penetration % year period. Of the 18 cases, Pipe* 4 Attlngo 100 DOC (SO 000 mileo of plpawork) Electric cabtoa 40 000 Hard flooring Packaging mr 30 000 Watar mains. rainwater plpa, soli plpa. electrical conduit House wiring. motor vehicles. domostle appttencea, powar cabiaa TJIee A continuous Wnyf Aooring 30 00 n 39 100 too to-o 40-90 0 seven have occurred on one plant in the USA (B. F. Good rich), a further three in another US plant (Goodyear), with the incidence elsewhere being very low. Average exposure (a) Fell 4 film 94 000 (b> Botttoa 13 000 (400m. bottlaa) <c) Bottle etoaurea 0000 Records (phonographic) 31 000 (140m. rocorda) Cara to 000 Footwear SO 000 TOm. pairs Foil: margarinotubs, biscuits, ehocotataa Flim:froah moat 4 vegetables Fruit souaah. cooking oil. tweet Jera, food and drink products an racorda ere PVC Uphoiatary, roof Intoriora wiring Sheet (3S%) and ahos uppers 30-8# go so 30 100 M 100 lime of the known case* approaches 20 years. However, the levels of vinyl chloride monomer to which these workers were exposed, thought to be at least 1000 ppm., is ex tremely high com pared with present permitted levels. Colliery 000 conveyor bolting (about 1000 milaa) Underground safety hotting 100 Average exposure levels in tbc UK are now 5 ppm for plant and overseas as well as with govern- atmoopberes in ment departments, the actions neces ppm in plant atmospheres for produc sary to safeguard the health of workers tion of PVC from VCM. and generally and users and to make recommenda 0-5 ppm in plant atmospheres for fabri tions for their speedy implementation.'' cation of PVC articles. Vinyl chloride A major reason for the committee's absorbed in a human diet is about 0*001 determination to arrive at a satisfactory ppm of the diet. solution to the VCM carcinogeoity Thus the Cl A considers that the problem is the importance of PVC to problem, if one still exists, is confined the UK national economy. to the industrial process of converting Four companies, BP Chemicals, 1CI. VCM into PVC. Levels in food arc British Industrial Plastics and Vinatex infinitesimally small, and atmospheric (jointly owned by the National Coal exposure levels in the fabrication in Board and Conoco), produce 400000 dustry. where they may at present ton of PVC annually in the UK, in exceed 5 ppm. can easily he reduced volving 2000 workers. by improved ventilation, the CIA main Table / show* the extent of the tains. I herefure the ctuimulltv's work tv being fiAuwd i*n lltc VCM p4)mcrization process itself. It estimates that average atmospheric concentra tions in the UK were I 000 ppm in the 1945-1955 period, 400-500 ppm in I9I960, 300-400 ppm in 1960-1970. |s. ppm in mid-1973, and is now 50 ppm. Major improvements in the past six months have come mainly from the elimination of procedures which per. mined vinyl chloride to escape into Hu. plant atmosphere (within the prescribed limit of 200 ppm). Ultimate Levels Further improvement will come from detailed plant modifications to eliminate or reduce adventitious leaks, according to the CIA committee, with the ultimate Tor most existing plants at 10 ppm. However, entirely new plants using the latest available tcchnologv might achieve 5 ppm, as (he lowest possible level attainable, the CIA states. In contrast, OSHA, the US Govern ment body concerned with the VCM problem has just proposed a standard of less than 1 ppm for atmospheric VCM levels. The proposal is however open to public comment before heinu adopted as law and the US Society of the Plastics Industry1 has already re sponded by calling the new standard "excessively and unrealistically restric tive." Up till now a temporary limit of 5tl ppm has been established in the USA. Nevertheless a limit of less than I ppm is tantamount to a zero exposure, and therefore zero risk. The CIA stresses that it is impo-Mhh* to prove a zero risk. In the case VCM there has always been some risk, as VCM presents a fire and explosion risk very similar tu that of butane and other liquefied gases used for heating and lighting. There have been more deaths from fire and explosions of such materials than from industrial discjsc and in the case of VCM, on a world wide basis, more people have died from these causes in the past ten years than from cancer, the CIA committee stated. As far as fabrication of PVC is con cemcd, the CIA is recommending that fabricators achieve atmospheric concen trations of less than 5 ppm. However, the fact remains that the concentration of VCM in freshly-produced PVC ex plant is in the range of 200-400 ppm by weight, although the level drops on storage. Typical levels on delivery to a siisto mer arc around 250 ppm. hut aft r processing this drops further in Minv where between 0.5 and 20 ppm >'v weight, depending on the fjhricauun involved. RSV 0006616