[Also see: PVC: A Health Hazard From Production through Disposal Paul Goettlich 25oct01]
POLYVINYL CHLORIDE
Structural Formula. [~CH2CHCl~]n
M = 300,000 to 400,000
CAS No 9002-86-2
8063-94-3
51248-43-2
93050-82-9
RTECS No KV035000
Abbreviations. PVC (polyvinyl chloride), VCM (vinyl chloride monomer), ATBC (acetyl tributyl citrate), DEHP [di(2-ethylhexyl) phthalate], DEHA [di(2-ethylhexyl) adipate], DOA (dioctyl adipate), ESBO (epoxidized soybean oil), TMSN (tetramethyl succinonitrile).
Synonym and Trade Names. Armodour; Astralon; Bakelite; Exon; Hostalit; Igelite; Lucoflex; Lucovyl; Marvinol; Norvinyl; Opalon; Ortodur; Polychlorovinyl; Polytherm; Porodur; Trovidur; Viniplast; Viniplen; Vinnol; Vinoflex; Yugovinyl.
Composition. PVC is manufactured by polymerizing VCM. To increase the heat- and light-aging resistance of PVC, stabilizers are introduced. Different plasticizers (phthalic and phosphoric acids, etc.) are added to give it elasticity. Plasticizer contents can vary from 3.0 to 80% which produce a considerable effect on material properties. With time, plasticizers can migrate to PVC article surface carrying other components of the composition (e.g., stabilizers) with them. PVC materials without plasticizers are referred to as rigid-vinyl plastic.
Properties. The structure of this polymer is relatively tight, but some air will pass through it. PVC has a heat distortion temperature of 72°C and a maximum continuous service temperature of 65°C. Because its shrink and melt points are so low, PVC can be used to shrink wrap foods which will tolerate very little heat. It is resistant to water, acid, bases, some solvents, fats, and oils. It is a carbon-chain linear polymer of amorphous structure. Solid white translucent material. Dens. 1.35 to 1.43. The properties of PVC highly depend on the method of its production: in the case of block or suspension polymerization, the polymer is lighter, more readily releases different low-molecular-mass impurities, and possesses higher water and heat resistance than emulsion-synthesized PVC. Even a small increase in the proportion of emulsion PVC in the composition leads to increased intensity of migration of its components.
Applications. PVC is approved for use as the film to wrap fresh red meats because it allows enough air to go through the package to make the meat pigments "bloom" bright red. PVC is prior sanctioned for use in general food-contact applications. The heat sealing range is from 90 to 180°C. It is used in the production of food containers, molded articles, and water pipes.
Migration Data. There are some indications of possible migration of VCM, stabilizers, and plasticizers from PVC. The maximum amount of VCM is released from rigid PVC into fat-containing products and alcoholic drinks (VCM contents in PVC exceed 30 mg/kg): 0.21 mg/l in a dry martini, 0.12 mg/l in gin, 0.25 mg/l in Sherry, 0.19 mg/l in whisky.1 The authors do not consider given concentrations to be health hazards.
VCM contents of PVC articles in contact with food products and of the products themselves are regulated in EU countries at a level of 1.0 and 0.05 mg/kg, respectively. Migration of VCM into water amounts to 0.01 to 0.2 mg/l (exposure from 1 week to 12 months). When VCM contents in the polymer amount to 10 mg/kg, 0.03 mg/l of the monomer was released into water from PVC bottles within 3 months, but with VCM contents of the polymer of 1.0 mg/kg, no monomer was released into water (Daniels and Proctor, 1975). Ando and Sayato point out that with time there is a greater probability of VCM reacting with chlorine dissolved in water and its transformation into chloroacetic anhydride, chloroacetic acid, etc. There is no migration of VCM into water when its contents in PVC are 2.0 pg/kg.2
There is no evidence that VCM can migrate from PVC pipes into water in a quantity that can be a health hazard and stay in water for a long enough time to cause undesirable effects. In contrast to industrial conditions where VCM inhaled with the air can accumulate in the blood and form metabolites with a carcinogenic and mutagenic effect, such accumulation is impossible with occasional entry of VCM into human body in trace amounts with water or food.3
VCM tetramer migration has been studied as a representative oligomer that has the potential for migration from PVC packaging. Tetramer levels in PVC bottles for retail beverages ranged from 70 to 190 mg/kg. No tetramer migration was observed into the simulants, such as distilled water, 3.0% acetic acid, 15% ethanol, and olive oil (detection limit of 5 to 10 µg/kg).4
60% of the PVC films declared for use in contact with fatty foods showed too high overall migration. Migration of phthalates from PVC into water has been the subject of many investigations.5-10 In most instances, DEHA made up about 80% of the total amount of plastic constituents migrating to isooctane.11
PVC films were exposed to the official food simulant, olive oil, or to isooctane. DEHA were determined by combined capillary GC-MS. Migration exceeding the specific migration limit of 4.0 mg/cm2 was found in 42 films (89% of the samples) and these films were deemed to be illegal according to their present declared field of application as given by their labeling.12 Diethyl ether extracts of food-contact PVC were analyzed by GC-MS methods: DEHA, dinonyl phthalate, and other phthalates were present in relatively large quantities (10 times higher than the internal standards). However, 68% of the extracts contained no peaks higher than the internal standards.13 The static migration test of a PVC film (children's sucking and biting) containing approximately 30% DEHP with saliva simulant gave the lowest values of DEHP; simple shaking increased the amounts of DEHP from 25 to 499 µg/g film.14
Migration of DOA from plasticized PVC into both olive oil and distilled water during microwave heating was studied. Migration into olive oil reached equilibrium after heating for 10 min at full power (604.6 mg DOA/l). Migration into distilled water was 74.1 mg/1 after 8 min at full power.15
Migration of DEHP from plasticized PVC tubing used in commercial milking equipment reached 30 to 50 µg/kg. Retail whole milks from the UK contained 35 µg DEHP/kg.5 No differences in migrated amounts between food-grade PVC irradiated with y-radiation and non-irradiated samples of food-grade PVC were observed. The amount of ATBC that migrated into olive oil after 97 hours of contact was non-detectable (<1.0 mg/l at 4 to 5°C). Concentrations of ATBC at 20°C, after 29 and 94 hours were 3.3 and 5.1 mg/l, respectively.6 At 20°C, traces of plasticizer dioctyl phthalate migrate into water from PVC water pipes containing 8 parts of plasticizer. At 37°C level, of migration amounted to 0.1 to 0.16 mg/l.
The introduction of fillers (chalk, barium sulfate, etc.) into plastisols reduces migration of plasticizers, but elevated contents of ESBO in PVC (> 3.0%)increases migration of dioctyl phthalate.028 The contents of TMSN, the main decomposition product of 2,2'-azobisisobutyronitrile in PVC products used for food packaging, were examined. The TMSN concentration in 17 PVC products ranged from 0.05 up to 523 mg/kg. The release of TMSN from two PVC products into five kinds of food-simulating solvents (60°C; 30 min.) was observed. When pieces of the bottle were stored in olive oil at 40°C for 120 days, 5.0 mg/kg of TMSN was detected in the oil.16
ESBO is used as a plasticizer and heat stabilizer in PVC films and gaskets. Levels of ESBO in fresh retail meat samples wrapped in PVC film ranged from less than 1.0 to 4.0 mg/kg, but were higher (up to 22 mg/kg) in retail cooked meat. Migration into sandwiches and rolls from take-away outlets ranged from less than 1.0 to 27 mg/kg depending on factors such as the type of filling and the length of the contact time prior to analysis. When the film was used for microwave cooking in direct contact with food, levels of ESBO from 5.0 to 85 mg/kg were observed, whereas when the film was employed only as a splash cover for re-heating foods, levels ranged from 0.1 to 16 mg/kg.9
Stabilizers calcium stearate, ricinooleate, magnesium and sodium stearate are non-toxic, but their stabilizing effect is low. They are used mainly for their synergistic effect. PVC stabilized with lead, cadmium or organotin is considered unacceptable.
Stabilizers used now form metal chlorides that to some degree are soluble in water. Intense flow of water and its temperature result to more intense washing out of lead stabilizers. When over 2.5% lead stabilizer is introduced in PVC, the amount of lead washed out is proportional to its contents in the composition, and it is washed out only from the surface layer of pipes. The bulk of lead is washed out during the first 2 to 3 days; later the process slows down. Considerable effect on washing out lead salts from PVC pipes has contents of CO2 dissolved in water. But small amounts of CO2 can even promote stability of lead because of formation of almost insoluble carbonate PbC03. On the other hand, lead hydrocarbonate which readily passes into solution, is formed with higher CO2 concentrations.
Barium compounds are normally used in synergistic mixtures with cadmium compounds. However, their use is limited by their high toxicity.
In some European countries dioctytin compounds are permitted in certain quantities as additives. Migration of organotins from PVC articles (clear food container, rigid pipe, and flexible membrane) into tetrahydrofuran, xylene and methylene chloride was investigated. Methylene chloride extracted >97% of the total extractable organotins in two extractions. There were <0.3 to 4.7 mg butyltins/g and <0.8 to 8.8 mg octyltins/g solvent. In industrial application, pipe samples were 43 to 1.5 mg butyltins/g and 0.7 to 3.0 mg octyltins/g PVC.17
An investigation of the migration of a sulphur-containing organotin stabilizer (dioctyltin diisooctylthioglycolate) showed that the level of migration is lower when the stabilizer contents in the composition are reduced. The maximum release was observed at 60°C after 5 days contact of PVC with water.18 At 20°C, 0.36 to 0.52 mg/I were released after 24 hours. Matos et al. found out the low levels of migration of mono- and dioctyl derivatives of organotin stabilizers. After contact for 2 years at 30°C, 3.0 µg tin were released from 1.0 dm2 (10 µg permitted).19 Concentrations of 0.1 to 0.122 mg dibutyltin-S,S'-(isooctylthioglycolate)/l were found in the extracts (1 to 2 cm-1; 20 to 60°C; 1 to 3 days).10
Migration of fatty acid amides from PVC used in food packaging and containing commonly used fatty acid amide slip additives into fat and aqueous food simulant was less than 0.05 mg/1(10 day, 40°C).20
Acute Toxicity. Rats received powdered PVC dissolved in sunflower oil at the dose of 2.5 g/kg BW for 14 days. There were no acute changes reported.18
Repeated Exposure. Capsules containing PVC in the from of 6 x 6 mm lumps, shreds, or powder were administered twice a day for 5 days to male dogs (PVC dose 125 mg/kg BW). No changes in the blood and urine parameters were noted. PVC was excreted with the feces unaltered. No morphological changes were reported.21
Long-term Toxicity. Male rats received aqueous extracts of PVC (1 cm-1; 20°C; 15 days) instead of water over a period of 12 months. There were no changes in BW gain, peripheral blood, biochemical indices, or liver function. Lead contents in the liver and bones were slightly higher than in the control animals, though histology of the viscera was not affected.18 Aqueous extracts of Miplast (emulsion PVC K-62) had no toxic effect on rats during 8 months of exposure.22
Aqueous and oil extracts of PVC P-73-M films containing 1.5 parts organotin stabilizers OTS-IS and SSM-9/68 given for 12 months did not have any clinical toxic effect on rats. However, to the end of the study with the oil extracts, there was reduced synthesis of hippuric acid, a slower removal of bromosulfalein from the blood, and depressed activity of mixed-function oxidases.8
Reproductive Toxicity. Epidemiological studies of adverse pregnancy outcome showed no association between PVC contact and the incidence of spontaneous abortion.23 No terata was reported in mice.24
Immunotoxicity. Local hypersensitivity was observed in guinea pigs during inhalation of a PVC mixture containing dibutyl phthalate and orgnochlorine compounds for 3 weeks.25
Carcinogenicity. PVC induced malignant tumors in rodents following s/c imbedding of polymer films.026 Nevertheless, the results of this study were later considered inadequate. Rats received total dose of 200 g/kg BW for 30 weeks. The material is equivocal tumorigenic agent by RTECS criteria.26
Carcinogenicity classification. An IARC Working Group concluded that there is inadequate evidence for evaluation of the Carcinogenicity of PVC in experimental animals and in humans.
IARC: 3
Regulations. U.S. FDA (1998) approved the use of PVC (1) in adhesives as a component (monomer) of articles intended for use in packaging, transporting, or holding food in accordance with the conditions prescribed in 21CFR part 175.105; (2) in the manufacture of resinous and polymeric coatings for polyolefin films for food-contact surface of articles intended for use in producing, manufacturing, packing, processing, preparing, treating, packaging, transporting, or holding food, in accordance with the conditions prescribed in 21 CFR part 175.320; (3) in the manufacture of resinous and polymeric coatings for the food-contact surface of articles intended for use in producing, manufacturing, packing, processing, preparing, treating, packaging, transporting, or holding food for use only as polymerization cross-linking agent in side seam cements for containers intended for use in contact with food (only of the identified types), subject to the conditions prescribed in 21 CFR part 175.300; (4) as a component of the uncoated or coated food-contact surface of paper and paperboard intended for use in producing, manufacturing, packaging, processing, preparing, treating, packing, transporting, or holding dry food of the type identified in 21CFR part 176.170 (c); (5) in the manufacture of semirigid and ńgid acrylic and modified plastics used as articles intended for use in contact with food in accordance with the conditions prescribed in 21CFR part 177.1010; and (6) in the manufacture of cellophane for packaging food in accordance with the conditions prescribed in 21 CFR part 177.1200.
References:
1. Davies, I. W. and Peny, R., Environ. Pollut. Manag, 5, 22, 1975.
2. Ando, M. and Sayato, W., Water Res., 18, 315, 1984.
3. Petersen, J. H., Lillemark, L., and Lund, L., Migration from PVC cling films compared with their field of application, Food Addit. Contam., 14, 345, 1997.
4. Castle, L., Price, D., and Dawkins, J. V., Oligomers in plastics packaging. Part 1: Migration tests for vinyl chloride tetramer, Food Addit. Contam., 13, 307, 1996.
5. Castle, L., Gilbert, J, and Eklund, T., Migration of plasticizer from polyvinyl chloride) milk tubing, Food Addit. Contam., 7, 591, 1990.
6. Goulas, A. E., Kokkinos, A., and Kontominas, M. G., Effect of gamma-radiation on migration behavior of dioctyladipate and acetyltributylcitrate plasticizers from food-grade PVC and PVDC/PVC films into olive oil, Z Lebensm. Unters. Forsch., 201, 74, 1995.
7. Sheftel, V. O. and Katayeva, S. E., Migration of Harmful Substances from Polymeric Materials, Khimiya, Moscow, 1978 (in Russian).
8. Zinchenko, T. M., Hygienic Evaluation of Phthalate Plasticizers of PVC, Author's abstract of thesis, Kyiv, 1988, 20 (in Russian).
9. Castle, L., Mayo, A., and Gilbert, J., Migration of epoxidised Soya bean oil into foods from retail packaging materials and from plasticized PVC film used in the home, Food Addit Contam., 7, 29, 1990.
10. Sheftel, V. O. and Grinberg, I. M., Migration of harmful chemical substances out of polyvinyl chloride materials used in water supply, Gig. Sanft, 8, 78, 1979 (in Russian).
11. Sheftel, V. O., On the risk of vinylchloride migration into water and food-stuffs, Gig. Sanft., 2, 63, 1980 (in Russian).
12. Petersen, J. H. and Breindahl, T., Specific migration of di-(2-ethylhexyl)adipate (DEHA) from plasticized PVC film: results from an enforcement campaign, Food Addit. Contam., 15, 600, 1998.
13. van Lierop, J. B., Enforcement of food packaging legislation, Food. Addit. Contam., 14, 555, 1997.
14. Steiner, L, Scharf, L., Fiala, F., and Washuttl, J., Migration of di(2-ethylhexyl) phthalate from PVC child articles into saliva and saliva simulant, Food Addit.Contam.,15, 812, 1998.
15. Badeka, A. B. and Kontominas, M. G., Effect of microwave heating on the migration of dioctyl adipate and acetyltńbutylcitrate plasticizers from food-grade PVC and PVDC/PVC films into olive oil and water, Z. Lebensmit. Unters.-Forsch., 202, 313, 1996.
16. Ishiwata, H., Inoue, T., and Yoshihira, K., Tetramethylsuccinonitrile in polyvinyl chloride products for food and its release into food-simulating solvents, Z Lebensm. Unters. Forsch., 185, 39, 1987.
17. Forsyth, D. S., Dabeka, R, Sun, W. F., and Dalglish, K., Specification of organotins in polyvinyl chloride) products, Food Addit. Contam., 10, 531, 1993.
18. Sheftel, V. O., Hygiene Aspects of the Use of Polymeric Materials in the Water Supply, Thesis Diss., All-Union Research Institute of Hygiene and Toxicology of Pesticides, Polymers and Plastic Mateńals, Kiyv, 1977, 70 (in Russian).
19. Matos, C. M., Kroll, Y., Hoppe, H., Romminger, K., and Woggon, H., Migration of organic tin stabilizers of hard PVC packing mateńals in food, Z. Ges. Hyg., 33, 258, 1987.
20. Cooper, L and Tice, P. A., Migration studies on fatty acid amide slip additives from plastics into food simulants, Food Addit. Contam, 12, 235, 1995.
21. Johnson, W. S. and Schmidt, R. E., Effects of polyvinyl chloride ingestion by dogs, Am. J. Vet. Res., 38, 1891, 1977.
22. Selivanov, S. B., Hygienic Study and Evaluation of Reverse Osmosa Method of Potable Water Desalination by Filter- press Installation, Author's abstract of thesis, Moscow, 1977, 18 (in Russian).
23. Lindbohm, R. et al., Spontaneous abortion among women employed in the plastics industry, Am. J. Ind. Med., 8, 579, 1985.
24. Ungvary, G., Studies on the teratogenicity of PVC, Acta Morphol. Acad. Sci. Hung., 28, 159, 1980.
25. Shevchenko, A. M., Borisenko, N. F., and Pushkar', M. P., Professional Hygiene in the Manufacture of Polymers and Plastic Materials, Zdorov'ya, Kiyv, 1978, 16 (in Russian).
26. Costa, V. and Frongia, N., Oncogenic activity of polyvinylchloride, Pathologica, 73, 59, 1981.
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