PVC: health implications and production trends.

Poly(vinyl chloride) (PVC) is a complex plastic system. Individual components of the PVC system, including residual vinyl chloride monomer (RVCM) and certain additives, may pose risks of harm to human health. There have been significant reductions in the RVCM content of PVC resin since 1974, reducing the cancer risk of workers in PVC fabrication plants and consumers of PVC products. A "no-effect" level for vinyl chloride monomer (VCM)-induced carcinogenesis has not been found to date; therefore, the significance of human exposure to low levels of RVCM remains to be determined. Exposure to PVC dust may cause pulmonary dysfunctions. Pulmonary and other possible health effects of PVC dust require further study. The PVC plastics system should be characterized as to interactions among its various components and as to interactions of the components and the PVC system as a whole with biological systems.

In January 1974, B.F. Goodrich Chemical Company announced that three reactor workers in a poly(vinyl chloride) (PVC) polymerization plant had developed a rare cancer, angiosarcoma of the liver. Exposure to vinyl chloride was linked to development of angiosarcoma of the liver by subsequent epidemiological studies. Animal studies, several initiated before the B.F. Goodrich announcement, also link exposure to vinyl chloride (VCM) with development of cancer.
Regulations promulgated in the United States of America since early 1874 have resulted in the lowering of VCM concentrations in the atmosphere of PVC manufacturing plants, and decreased concentrations of VCM in PVC resin. This has reduced the cancer risk of PVC production workers, workers in PVC fabrication plants and the ultimate consumers of fabricated PVC products.
We are now at a crucial stage as regards studies of the effects of plastics and plastics components on human health. Human exposure to massive doses of VCM, whether due to uncontrolled venting of PVC polymerization vessels or the voluntary venting in a home bathroom of an aerosolized VCM hair spray, is essentially over. The time has come for study of possible health hazards posed by the complex plastic system called PVC. Why be concerned about PVC? A publication (1) states that: "Total world employment in the VCM and PVC producing industries is likely to be well over 70,000 workers. Those employed in industries which use PVC as a basic element are likely to total in the millions. Those who come in contact with PVC every day in some form or other probably make up about at least one-third of the human race." What are the human health effects of PVC?
There are several components of PVC which, on their own, could affect human health adversely: VCM, PVC dust considered as a dust, additives of various sorts. ("Additives" for our purposes includes stabilizers, colorants, flame retardants, plasticizers, fillers, etc.) But one cannot consider the components of PVC solely as independently acting potentially toxic agents. PVC is a complex chemical system with little-understood interactions, both physical and chemical, among its components. Leaving aside the multicomponents interaction problem for the time being, consider the individual components of PVC which may pose risk of harm to humans. VCM is already identified as a cancer-causing agent. Even given the reductions of VCM in PVC resin, which have been achieved by changes in both production and compounding procedures, some RVCM (residual vinyl chloride monomer) is still present in PVC. In 1974 Rowe (2) estimated the average monomer concentration of PVC resin to be approximately 1000 ppm. As shown in Table  1, RVCM concentrations of 100 ppm or less for suspension resins before compounding were not unusual by April 1975. An advertisement (3) run in July 1975 by a major manufacturer of PVC stated that general-purpose PVC homopolymers and blending resins were being produced with a maximum of 10 ppm, and usually less than 5 ppm, RVCM.* Tables 1-3, taken from a U.S. Environmental Protection Agency (EPA) publication (4) * The advertisement states (in part): "At Tenneco, we've developed a unique new production technology that allows us to produce our general purpose PVC homopolymer, blending and dispersion resins with no more than 10 parts per million of VCM(vinyl chloride monomer). In fact, the typical VCM content of these homopolymer and blending resins is less than 5 parts per million and under 3 parts for our dispersion resins. And, we are producing our flexible compounds at nondetectable(less than 1 ppm) levels.
"This is a 98%o to 99% reduction from what was once the typical practice of the industry for residual VCM." give some idea of the present RVCM in several PVC resins. In particular, note company E in Table 1. 86.8%c<G of suspension resin production is said to be at 0-50 ppm RVCM (with a footnoted qualification that "some values are speculative until improved stripping is installed".) Note also that for company A, 60% of whose resin had a RVCM concentration of 2000-4000 ppm in April 1975, with the remaining 40% at 4000-6000 ppm, "all suspension resins (were) to be reduced to less than 400 ppm RVCM by 7/75." Health problems which may be associated with RVCM in finished PVC resin are of importance to workers and consumers. The residual VCM in the old high-residue PVC evidently posed problems for workers in fabrication plants. Data collected by the United States National Institute for Occupational Safety and Health (NIOSH) indicate that several angiosarcoma cases were identified in fabrication plant workers in this country and abroad (  October 1976 Table 4. Reported cases of angiosarcoma of the liver among nonpolymerization workers exposed to vinyl chloride. i Diagnosis: sarcoma (possibly "angiosarcoma"), liver. Possibility of generalized neoplasm of the reticuloendothelial cell system cannot be ruled out.
k Accountant at plant making PVC fabric.
exceeded the 1 ppm 8-hr time-weighted average currently permitted by OSHA. How low must you go before RVCM ceases to represent a hazard? A "no-effect" level for VCM carcinogenesis has not been found to date; cancer has been found in all groups of animals tested with nonzero concentrations of inhaled VCM. Just how low are the VCM concentrations in fabrication plants now? Publication of monitoring data would be useful for analysis of possible risks of harm to health.
A fabricated PVC product category with wide consumer exposure is PVC automobile upholstery, rooftops, and interior fittings. The Given the number of individuals exposed to "new car atmospheres" and cars or other motor vehicles generally, some further data on the RVCM content of PVC auto fittings might be useful.
Even if risk to consumers from RVCM in PVC seat covers is low, what is the risk of harm to persons working in automobile factories ?
A recent study by Infante et al (10) is especially interesting. The data collected by Infante have been interpreted to suggest that VCM may exert a mutagenic effect on sperm cells of PVC production workers, leading to an increase in fetal deaths among pregnancies of workers' wives. Infante's findings are not surprising in light of the demonstration by Ducatman et al. (11) of chromosome aberrations in PVC production workers and the finding by Ames (12) that VCM is mutagenic in a Salmonella test system. The sewing of vinyl automobile upholstery and other vinyl fabric automobile fittings is, evidently, in large part woman's work. Even given the multicomponent nature of the PVC in auto fittings, it might be interesting to determine the incidence of cancer, stillbirths, and birth defects in offspring among women vinyl auto upholstery workers.
What happens to PVC on pyrolysis? There seems to be some disagreement as to whether VCM is liberated (13) or whether the principal health threat from burning PVC is caused by evolution of HCI (14,15). Has there been a definitive demonstration that VCM is not evolved during pyrolysis of PVC? What about depolymerization on aging? in sunlight? in heat? PVC exposure has been linked both to dermatitis and Raynaud's syndrome or occupational acroosteolysis (16). Dermatitis could be attributable to several of the additives in PVC, or possibly to VCM itself. A catalog of resin components which have caused skin sensitization reactions would be useful.
One of the important consumer uses of PVC is in food packaging. Regulations recently proposed by the United States Food and Drug Administration (FDA) (17) deal with PVC food packaging. Although industry data (18) have been presented to FDA which indicate migration of VCM from PVC as below 50 ppb (the "lowest detectable" level established by the FDA proposal), challenges (19) have been raised to permitting use of PVC food wrap if there is any RVCM capable of migrating.
The debate about PVC food wrap points up what may be the salient characteristic of PVC considered as a source of residual VCM: RVCM contained in PVC has now joined the ranks of other carcinogenic substances whose presence in trace amounts-the amounts limited only by the means of detection-in the US food supply is forbidden by the Delaney Clause, an amendment to the United States Food, Drug and Cosmetic Act. That clause reads in pertinent part: ". . . no additive shall be deemed to be safe if it is found to induce cancer when ingested by man or animal, or if it is found, after tests which are appropriate for the evaluation of the safety of food additives, to induce cancer in man or animal . . ." (20).
FDA's attempt to set a nonzero tolerance for VCM in food wrap has been challenged as illegal due to conflict with the Delaney Clause (19). It may be that final promulgation of a proposal setting a nonzero tolerance for RVCM in food wrap will be challenged in the courts.
Efforts to reduce VCM residual in PVC have come a long way in just over two years. The industry has demonstrated its ability to reduce VCM levels in PVC production plants from hundreds or thousands of ppm to a level close to or at the OSHA 8-hr TWA of 1 ppm.
Since chemical reactions rarely go to completion and are usually reversible, will it ever be possible to produce a PVC resin completely free of residual VCM and incapable of breaking down to release VCM? The stumbling block for the continued health and growth of the PVC industry may well prove to be not the threat of massive doses of VCM and high potential risk of cancer for the few, but the threat of low doses of VCM and a low but nonzero risk of cancer for the many.
The preSence of RVCM in PVC represents a potential health hazard for the large number of humans exposed to resin or, more commonly, finished plastic goods. The dusty nature of PVC resin may represent a health hazard for persons with an occupational exposure to PVC.
Where could PVC dust represent a significant hazard? In a polymerization plant, work stations which could be dusty include drying and bagging areas, storage rooms or silos where PVC resin is held for shipment, mixing areas in compounding and/or fabrication facilities, and baghouses or cyclones in production or fabrication facilities. If the dusty operations are not completely isolated from the remainder of the production or fabrication facility, dust hazards could be present throughout the plant.
How dusty do PVC plants get? Two photographs (Figs. 1 and 2) taken in 1975 in a large PVC polymerization facility in the U.S. (21) may be of interest. Figure 1 gives a general idea of the powdery coating on the equipment in the bagging area; Figure 2 is a picture of the floor of the plant: note the depth of the dust, as indicated by the footprints.
PVC dust concentration data are not readily available; at least, the author had difficulty obtaining such data from labor, government, academic, and industry sources. It would be very helpful to those interested in problems of dustcaused disease for industry, labor or government to take measurements of PVC dust in the workplace and make them public.
Particle sizes within the respirable range have been noted (W. J. Nicholson, Mt. Sinai School of Medicine, personal communication, A number of clinical studies (22)(23)(24) have demonstrated pulmonary abnormalities in PVC production and fabrication workers. Abnormalities have ranged from decreased pulmonary function as measured by FEV to pulmonary fibrosis. Given the data currently available, work is needed to separate the effects on the lung and respiratory system of VCM from those of PVC dust.
Experimental studies associate pulmonary fibrosis with exposure of animals to PVC dust. In a recent paper from Italy, Frongia et al. (25) performed a series of studies with a simple basic plan-place guinea pigs or rats in cages in the bagging area of a PVC polymerization plant and observe the effects on the animals' lungs. These animal experiments were inspired by a clinical report of PVC-induced pneumoconiosis (26). The Frongia group, after microscopic examination of tissues of the animals under study, concluded that they had demonstrated a pneumoconiotic reaction brought on by PVC dust. Experiments reported as "in progress" as of late 1974 were designed to de-termine whether the pulmonary fibrosis was reversible on cessation of exposure to PVC. Data on reversibility of pulmonary and respiratory effects of PVC exposure should also be obtained for human populations.
Work is needed to determine whether VCM exposure heightens pulmonary response to PVC dust or whether, conversely, PVC dust may convey low levels of VCM or additives to the lungs.* Possible enhancement of dust effects by other chemicals in the work atmosphere and/or the additives in the PVC resin should also be investigated.
PVC dust could also be swallowed. Volkheimer (27) has found that PVC particles can * According to Miller et al. (23) ". . . If exposure to vinyl chloride and/or PVC is causally related to air flow impairment, we do not know which substance is more pathogenic. The fine dust of the polymer might be more likely to concentrate in and damage the small airways. This dust, and other small respirable particles, perhaps from tobacco smoke, may also serve as carriers for molecules of a monomer gas to settle in these airways." October 1976 113 111..?..
-VI be "persorbed" from the intestine into the lymph or blood systems. The effect of locally high concentrations of PVC particles carrying minute amounts of potentially leachable RVCM or additives merits investigation, especially as concerns contact with lung or liver tissue.
The possibility of PVC dust serving as a skin irritant should be explored. PVC dust could serve as an efficient means for bringing a sensitizing compound into contact with the skin.
The suggestive nature of the clinical and experimental data available at this time supports reduction of PVC dust levels in polymerization, comnounding and fabrication facilities. The OSHA standard (28) does not include PVC dust protection or reduction regulations, although such regulations were recommended by NIOSH.t Major categories of PVC additives are colorants, fibrous reinforcements (e.g., asbestos), flame retardants, plasticizers (e.g., phthalic acid esters) and stabilizers (e.g., organotin compounds) (28). Based on experimental and/ or clinical data, questions are in order as to the safety of representatives of each of these chemical classes.
For instance, Ames (29) has recently reported that a certain flame retardant compound used in children's sleepwear is highly mutagenic in a Salmonella test system. Compounds exhibiting mutagenic activity in this bacterial test system are likely to be carcinogens as well. What about the toxicity of flame retardants used in PVC plastics?
In September 1972, NIEHS held a conference on phthalic acid esters (30). What is the t To date, neither the US OSHA nor the US EPA has taken any specific steps to reduce PVC dust considered as dust. Dust reduction and protection was recommended to the OSHA by NIOSH; EPA in its standard support document (4), states: "With regard to the potential problem of polyvinyl chloride particulate as a possible cause of pneuumoconiosis, NIOSH is currently involved in experimental studies on the effects of the particulate in animals. The extent of public exposure (as opposed to occupational exposure) to ambient concentrations of the particulate is unknown at this time. Ambient measurements of polyvinyl chloride particulate have not been made by EPA in the vicinity of industrial sources because no techniology is currently available for separating polyvinyl chloride particulate from total suspended particulate. As data become available from NIOSH and other sources on the health effects of polyvinyl chloride particulate, EPA may find that it is necessary to reevaluate the need to propose standards for polyvinyl chloride particulate." current thinking of regulators and researchers regarding the safety of these chemicals?
There is considerable documentation of toxic effects of certain organotin compounds (31). The biocidal activity of organotin compounds, several of which are being used as pesticides at present, should cause concern about possible effects of organotin plastics additives on human health.
The possibility of complex interactions among PVC plastics components and between the components and living systems should be emphasized. Most probably, very little is known about these interactions.
NIEHS has in progress projects designed to identify chemicals which should be studied for possible adverse health effects for humans. Because of its wide population exposure due to enormous production volume and broad spectrum of uses and health problems already associated with VCM and PVC dust and certain additives, PVC seems a likely candidate for further investigation.
Given the current state of scientific knowledge-at least as regards data available for public scrutiny-producers and fabricators of PVC cannot assure the public that PVC plastics are safe for human use.
Therefore, interested scientists the world over, whether working for industry, government, or labor unions, or engaged in research at universities, should make a concerted effort to collect and analyze such data as are available at present on possible risks of harm to human health attributable to PVC. Scientists should identify research which should be carried out to determine whether or not the family of PVC plastics is safe for general use, and seek the necessary funding to carry out whatever studies are needed.