Document RpdXb2q841R7rYM9nbjZGNYkv

<''7 / sri-fz R&S 004066 Environmental Health Perspectives Vol. ]?, pp. 237-230, 1073 Recent Achievements and Research Initiated in the Swedish Plastics and Rubber Industry * by Anders Engiund* and Bo Holmbergt The improvement in exposure conditions in the Swedish vinyl chloride producing industry is reported. The article comments on the technology and control methods by which the vinyl chloride concentration has been lowered to less than 1 ppm vinyl chloride. Two epidemiological retrospective cohort studies are presently under way on workers in PVC-utiiizir.g industries and in the rubber industry. In the spring of 1974 a search for cases of low value has been argued not only in Sweden liver tumors led to the detection of two cases but also in other countries. A look at the efforts of angiosarcoma of the liver among workers in work hygiene in the factory is, however, in the vinyl chloride/poly (vinyl chloride) (VC/ encouraging. PVC) industry (l).1 Since then, an epidemio The factory was erected at Stockvik, north logical survey reported in this symposium (2) ern Sweden, in 1945 and produced VC mono has been performed without revealing any ex- mer as well as PVC resin until 1968/1969, xess cancers of other sites, when monomer production was halted. At the b Until April 1974, the official permissible con same time the standard of work hygiene was centration for VC was 509 ppm time-weighted partly improved. The factory today employs average (TWA) although the VC/PVC pro around 100 workers in PVC production, and ducing industry with certainty normally did the company concerned is one of two existing not exceed 100 ppm during the last few years. companies in Scandinavia. The production ca In April 1974 a temporary permissible concen pacity in this particular plant was around tration was set at an 8-hr TWA of 20 ppm 6 X *10r kg PVC in 1975. with 50 ppm as a ceiling value. In the autumn of 1974, a low value was discussed among ex perts, but the Swedish company did not agree upon the technological and economical feasi bility of a low-risk-standard around 1 ppm. In October 1974, however, 1 ppm TWA for VC was settled with a ceiling value of 5 ppm as a 15-min average. The impossibility of such a Table 1 (3) shows the arithmetic means of dose measurements in the Stockvik plant dur ing 1974-1975. The mean values as well as the highest and lowest measured values decrease markedly with time and with the improvement of work hygiene technology. As soon as mid1975, half a year before time demanded, the company was able to achieve the permissible concentrations. * Larulsoi-gauizationen i Sverige, Baiuhusgatan 18, What kinds of control are maintained on the s, S-105 53 Stockholm, Sweden. exposure levels and by what means were the t Section of Occupational Toxicology, Department of Occupational Health, National Board of Occupational concentrations lowered? Air samples are auto Safety and Health, Fack, S-100 26 Stockholm, Sweden. matically taken at 2S fixed sampling sites (Fig. t On March 20, 1076 a third man died at the age of 1). The air sample is fed into a centrally lo Cl in a hemangiosarcoma of the liver. He was employed cated analysis apparatus during 24 sec. A sam as an autoclave operator from ]0-17 to 1968, when he left the company. Since 1973 he was granted sick pen sion due to angina pectoris. The tumor disease was asymptomatic until one month prior to the death. ple is taken at a particular sampling site every 15 min. Gas chromatographic analyses on hy drocarbons are performed automatically and ctober 1976 237 Table I. VC dose measurements at tbe Stockvik PVC production plant.* April-June July-Sopt. 1974 1974 Oct.-Dee. 1974 VC, ppm Jan.-March April-June 1975 1975 July-Sept. 1975 Arithmetic mean Highest value Lowest value Percentage employees exposed to less than 1 ppm No. of measurements 12.2 10G 1.3 0 42 7.7 29.5 2.G 0 29 3.4 13.9 0.4 3 32 1.3 4.8 0.1 26 40 1.1 3.0 0.2 74 4G 0.7 4.5 0.1 89 40 Oet.-Dec. 1975 0.G 10.5 0.1 100 46 Data of Norgren (5). recorded. Should the content of VC/hydrocar bon in the air sample exceed 5 ppm, a warning lamp at the sampling site turns on to warn the workers (Fig. 1). The work environment in the PVC plant was improved by application of already known ventilation technology and by closing the proc ess cycle by recirculation of VC- The general ventilation was improved by an increase in air inflow and outflow. The impact of an increased general ventilation was further enhanced by a stabilization of the air flow by air jet streams. (Fig. 2) At the point where leakage occurred, special ventilation was arranged in order to take care of leaking monomers (Fig. 0). In the autoclave area, a mobile ventilation unit can be transferred to a site where a local leak- R&S 004067 Figurk 1. Stationary sampling unit with warning lamp in a PVC producing department. Fict'RF. 2. Ventilation equipment with air inflow at window wall. Air exhaust behind the autoclaves, the bottoms of which are seen to the left. Jet streams from the roof to the left of the pillar stabilizes air stream as seen by smoke indicator. 238 Environmental Health Perspectives equipment was designed. The picture shows such equipment at a tube joint. age has been detected. Before a worker enters an autoclave, fresh air is blown into the auto clave. Workers must wear masks during auto clave cleaning. The financial investment for work hygiene improvements in the Stockvik plant was around 20 million Swedish Crs. (approx. $4.5 million). The conclusions to be drawn from the Swed ish VC/PVC experience are that the techno logical and economical considerations initially expressed by industry are not always valid and that setting a low occupational health standard may govern the technological development. Industries engaged in fabrication of PVC, which employ between 3500 and 5000 workers have had a better start for improvement of their work hygiene as far as exposure to VC monomer is concerned. Improvements have been made by improving ventilation in fabrication and by modifying the PVC resin produc tion process in PVC manufacture so as to leave less residual VC monomers in the resin. This last effort is ongoing and the goal is to produce a resin with less than 0.001 rr residual mono mer. Measurements of TWA dose in four major companies investigated, which produce carpet material, textile fabrics, food packaging, plastic film and tubing, do not normally exceed 0. 1.ppm today. An epidemiological retrospective cohort study is presently under way. A total of about 2100 workers will be checked with the cancer registry and with the national registry for causes of death. The reason for making a sur vey in the fabricator industries is to evaluate the possible risk for excess cancer due to past exposure, which certainly has been higher than today's, but has certainly not been as high as in the PVC production plant- In the rubber industry an epidemiological study on possible health hazards among Swed ish rubber workers has been begun. Two major Sw'edish rubber companies are included in the study on a cooperative basis. The trade union, the companies, and the National Board of Occu pational Safety and Health are all involved. The population at risk is now estimated to be around 5000, with at least 700 workmen from weighing and compounding departments. REFERENCES 1. Byron, D., and Holmbcrg, B. Two possible cases of angiosarcoma of the liver in a group of Swedish vinyl chloride-polvvinvl chloride workers. Ann. N.Y. Acad. Sci. 2-16: 2-10 (1975). 2. Byron, U., ct al. Mortality and cancer morbidity in a group of Swedish VCM and FVC production work ers. Environ. Health Perspect. 17: 1C7 (197C). .'1. Norgren, M. An lever PVC-industrin. (Swedish). Tckn. Tidskr. J97C: No. 1-2, 24. R&S 004068 October 1976 239