Pulmonary Manifestations of Vinyl and Polyvinyl Chloride

Abstract

Communications for this section will he published as space and priorities permit. The comments should not exceed 350 words in length, with a maximum of five references; one figure or table can he printed. Exceptions may occur under particular circumstances. Contributions may include comments on articles published in this periodical, or they may be reports of unique educational character. Specific permission to publish should be cited in a covering letter or appended as a postscript. To the Editor: I would like to comment on the paper of E. M. Cordasco, et al, entitled “Pulmonary Manifestations of Vinyl and Polyvinyl Chloride (interstitial lung disease): Newer Aspects,” (Chest 1981; 78:828–34) and caution against any premature conclusions reached from this paper. While their article supplies interesting information, it does not substantiate their main contention that the three cases represent what they call vinyl chloride/polyvinyl chloride lung disease. Instead, each case is completely different and not really comparable. The first case represents an alleged pulmonary disease from the inhalation of pyrolysis products of PVC meatwrapping film. The second case is an apparent exposure to vinyl chloride fumes; the third case represents one where the exposure is polyvinyl chloride resin dust. Each of these materials has different properties and characteristics and should not be considered a specific entity. Furthermore, the environmental information concerning exposure in each case is extremely scanty and limited. Therefore, having three individual cases of completely different exposures, and having little information on the specifics of the exposures does not constitute a designation of a disease entity. This fact should be made clear! The first patient described was a meat wrapper exposed to PVC film thermal decomposition products as well as emissions from the adhesive heat label. The exact details of the latter exposure were not given. Blood tests for phthalic anhydride were said to be elevated. Phthalic anhydride was said to be a decomposition product of PVC. This, unfortunately, is not the case. The thermal decomposition of plain PVC has been studied extensively and emission products have been identified.1Vandevort R Brooks SM. Polyvinyl chloride film thermal decomposition products as an occupational illness.J Occupational Med. 1977; 19: 188-191Google Scholar, 2Encyclopedia of Polymer Science and TechnologyPlastics, Resins, Rubber, Fibers. 12 and 14. Interscience Publishers, New York1968Google Scholar, 3Madorsky SL. Thermal degradation of organic polymers. Interscience Publishers, New York1974Google Scholar, 4Palma G Carenza M. Degradation of poly (vinyl chloride). I. Kinetics of thermal and radiation-induced dehydrochlorination reactions at low temperatures.J Appl Polymer Sci. 1970; 14: 1737Crossref Scopus (58) Google Scholar, 5Gupta VA Piere LE. Thermal degradation of poly (vinyl chloride). 1. Structural effects in the initiation and decomposition chain lengths.J Polymer Sci. 1970; 8: 37Crossref Google Scholar, 6Boettner EG Ball G Weiss B. Analysis of the volatile combustion products of vinyl plastics.J Appl Polymer Sci. 1979; 13: 377Crossref Scopus (80) Google Scholar PVC alone is different from PVC meat packaging film, which also contains a number of selected additives including plasticizers (di-2-ethlhexyl adipate) which can comprise up to 30 percent of film. Major emissions from hot-wire cutting of PVC meat packaging film are hydrogen chloride and plasticizer breakdown products including di-2-ethylhexyl adipate. PVC is not part of the emissions, nor is VC. Since phthalic anhydride and phthalates are generally not part of the PVC meat wrapping film, the elevated blood phthalic anhydride level is not due to decomposition of PVC meat wrapping film. Materials such as DE HP, MEHP, phthalic acid and phthalic anhydride measured in tissue or blood cannot be presumed to be the result of exposure to pyrolysis products of plasticized PVC, nor from the metabolism of phthalate plasticizers. Phthalic plasticizers and phthalic anhydride are present in a number of commercial products. Unless one has information on what are normal blood and tissue levels, then a measurement in the blood cannot be given any special significance. The information concerning normal blood levels of the phthalate compounds is not given in the manuscript. Phthalic anhydride is a component of many plastic materials and also a constituent of the thermal-activated price label “hot-melt” adhesives.7Brooks SM Vandevort R. Polyvinyl chloride film thermal decomposition products as an occupational illness.J Occupational Med. 1977; 19: 192-196PubMed Google Scholar Thermal activation of the price labels is performed by heating the labels from the printed side with possible emissions being phthalic anhydride. Our group has studied populations exposed to this chemical and have not identified cases of interstitial lung disease, but have noted cases of bronchial asthma.8Maccia CA Bernstein IL Emmett EA Brooks SM. In vitro demonstraton of specific IgE in phthalic anhydride hypersensitivity.Am Rev Respir Dis. 1976; 113: 701PubMed Google Scholar Furthermore, a number of recent studies of meat wrappers have not demonstrated significant lung disease.9Jones RN. Respiratory health and polyvinyl chloride fumes.JAMA. 1977; 237: 1826Crossref Scopus (1) Google Scholar,10Krumpe PE Finley TN Martinez N. The search for expiratory obstruction in meat wrappers studied on the job.Am Rev Respir Dis. 1979; 119: 611PubMed Google Scholar I seriously doubt, therefore, that the interstitial lung disease described only in one case was due to exposure to PVC meat wrapping film emissions. The second case of the individual exposed to VC spray paint is perplexing. There is discussion on contents of a spray paint, indicating that vinyl chloride is one of the main components and not just a propellant. My information indicates that vinyl chloride is not used in this type of paint and therefore I question the accuracy of the information provided by Dr. Cordasco. Unfortunately, few environmental data are given and there are no details on other environmental exposures. VC is a potent carcinogen and for the past several years has been excluded as a propellant for commercial products.11Gamble J et al.Effects of occupational and nonoccupational factors on the respiratory system of vinyl chloride and other workers.J Occupational Med. 1976; 18: 659-670Crossref Scopus (7) Google Scholar The third case is also confusing. This case involves a 55-year-old man exposed to PVC dust during a reactor cleaning operation. Apparently, the exposure was transient, over a 5–6 week period. The only information we have concerning environmental air concentrations is the statement that PVC in the immediate operational area varied between 200–300 parts per million. This level is not possible. Dust measurements are made in particles per cubic feet of air or weight (ie mg or /μg) per cubic meter of air. Gases are measured in parts per million. Prolonged exposure to PVC has been reported to cause a pneumoconiosis, as indicated by Dr. Lilis in her commentary. Prolonged exposure is necessary and a 5–6 week exposure is unlikely to result in significant lung disease. In summary, therefore, I would again caution against reaching any definite conclusions from the findings in this paper. The environmental data are scanty and inconsistent and in many cases erroneous. Actual levels are lacking and all environmental contaminants have not been adequately identified. The authors have, unfortunately, fallen into the common trap befalling many practicing physicians of attributing an occupational disease to be present because a potentially toxic material is present in the work place, and without properly and accurately determining what the actual exposures are, in what concentrations, the duration of exposure, as well as properly excluding other agents and nonoccupational causes for the disease.