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Healthcare workers depend on medical gloves for hand protection. For over 40 years a synthetic polymer, polyvinyl chloride (PVC), has been used to manufacture examination gloves. Dr. William Abildgard, a medical doctor, invented PVC examination gloves as an alternative to natural rubber latex gloves. In 1958 Dr. Abildgard founded the Derma-Shield Corporation in San Jose California to commercialize his vinyl gloves. Since that time other companies have also been established to manufacture PVC examination gloves. Before the AIDS epidemic, the glove market was relatively small. Today it is a 40 billion units market that is growing every year. As users become more sophisticated regarding glove usage, manufacturers and chemical companies are developing new synthetic polymers. Currently, about 20 percent of commercially available medical gloves are produced from synthetic polymers such as PVC, block copolymer, nitrile, neoprene, and polyurethane. In response to the growing concern about latex allergy, the selection of appropriate gloves will become an even more challenging and confusing task.
This article intends to address the most common expectation and perception of vinyl gloves amongst glove users.
Although the production of polyvinyl chloride polymers was not commercialized until the 1930s, the chemistry and physical properties of polyvinyl chloride had been studied since vinyl chloride monomer was first prepared in the laboratory of Regnault in 1835. Through chemistry and engineering, these polymers have been processed into products that we often take for granted, such as PVC pipes that provide us with running water, insulate electrical wires, and many other conveniences. Consequently, PVC is the second most abundant industrial material versatile enough in its formulation to permit developing various synthetic compositions with a wide range of physical, chemical, thermal, optical, electrical, and other properties.
According to the Handbook of Plastics and Elastomers1 vinyl belongs to the plastic-material class of thermoplastic materials. It softens upon heating and hardens and takes the shape of the mold upon cooling. Other examples of thermoplastics are nylons, polycarbonates, polyurethanes, polyethylenes and polypropylenes. They are structurally based on the ethylene chain prepared from natural gas.
Although polyvinyl chloride (PVC) is the most widely used the vinyl family is comprised of seven major types that may not contain chloride. In addition to PVC, they are polyvinyl acetals, polyvinyl acetate, polyvinyl alcohol, polyvinyl carbazole, polyvinyl chloride-acetate, and polyvinylidene chloride (Saran). Vinyls are basically tough and strong, resist water and abrasion, and are excellent electrical insulators. They are not degraded by prolonged contact with water, oils, foods, common chemicals, or continuous exposure to temperatures ranging up to 130°F or higher. As resins, latexes, organsols, plastisols, and compounds, PVC is the world's second largest produced raw material with an estimated production capacity of 27.7 million metric tons in 1997.
Most flexible PVC is produced from plastisol. It is a liquid dispersion of fineparticle-size emulsion polyvinyl chloride in plasticizers. The use of phthalate as plasticizers began in the early 1920s. Waldo Semon (1933) found that PVC would form "rubber-like compositions" when it was dispersed in solvent and plasticizer. Adding plasticizer makes the resin softer and more flexible, reduces the modulus and tensile strength, and provides greater elongation. Thus, the theological and physical properties of the vinyl coating can be customized by using different molecular weights of PVC resin and a wide variety of plasticizers to produce materials of varying degree of tensile strength and flexibility. In general plasticizers for PVC resin are esters of aliphatic and aromatic di- and tricarboxylic acids. Secondary plasticizers include high-molecular weight alkyl aromatic hydrocarbons and chlorinated aromatic and aliphatic hydrocarbons.
As a result of its ease of fabrication and extremely good acid and alkali resistance, vinyls are used extensively in household, commercial, medical and consumer products. The following is a comparison between the composition of a vinyl and a latex glove.
| Vinyl Glove |
Latex - Natural Rubber |
| Resin |
Natural Rubber Latex |
| Plasticizer |
Activator - zinc oxide |
| Heat stabilizer |
Crosslinker - sulfur |
| Filler |
Antioxidant |
| Pigment |
Stabilizer - polyethylene oxide condensate Accelerator - zinc diethyl dithiocarbamate |
Polyvinyl chloride is prepared from the polymerization of vinyl chloride monomers - a product of ethylene and chlorine. All ingredients used must pass biocompatibility testing before submission to the FDA for 510(k) pre-market notification. The chance of any person having chemical reactions to the ingredients in PVC is relatively low. In contrast, some chemical accelerators used in the production of NRL gloves can cause allergic reactions such as contact dermatitis in some individuals. Studies on NRL have shown that more than 50 different proteins have been implicated in allergic responses, with up to a total of 240 different proteins found in latex.2 Therefore, as long as NRL continues to be the major raw material in latex gloves, there will always be a concern for some high-risk individuals regarding allergenic reactions to NRL.
A successful partnership between glove manufacturers and the healthcare industry depends on their continuing effort to maximize cost/performance ratios of the products and services they provide. Since the appearance of the AIDS crisis, the medical glove industry has been growing continuously to service the needs of the healthcare market. Many articles have been written about the barrier effectiveness of medical gloves that are made from natural rubber latex (NRL), vinyl, nitrile, and other alternative synthetic polymers. These studies have raised our understanding of medical gloves from an emotional level to a scientific and fact-based level.
Until there are materials that meet the cost/performance/availability relationship, vinyl will continue to be an alternative glove option for the healthcare industry. It is important that we understand the limitation of each material as well as the application to which the material will be exposed. As we become more sophisticated about our knowledge of gloves, the best protection is to apply the same kind of scrutiny to all the innovative, cost-effective synthetic polymeric gloves that are developed. However, under today's competitive environment, unless proper inputs are channeled to the materials manager or the group purchasing organizations, most procurement decisions will be based on cost containment and not on the expectation of the users. A 1993 study conducted by SmartPractice,3 a medical supply company, concluded that the best way to control costs lies in understanding what protective gloves can and cannot offer, and this requires an awareness of the features of a specific glove and the physical properties of its material.
As more hospitals are designating latex-safe operating suites, it is important to separate emotional, political, and social decisions from economic, business, and scientific decisions. Workplace decisions should be made to reduce cumulative exposure to latex, including the use of low-powder, low-allergen latex gloves and nonlatex gloves as appropriate.
REFERENCES
- Harper C.A., Ed. Handbook of Plastics and Elastomers, McGraw-Hill, Inc. New York (1975)
- Reddy S. Latex allergy. Am Fam Physician 1998;57:93-102, comment 42, 47.
- Hainann C.R, Kick S.A., Sullivan K., Taking up the gauntlet: Accepting the challenge of glove evaluation, J Healthcare Material Management, September 1993
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