Special Report

Flexible PVC Faces Stiff Competition

Despite a series of challenges on health and environmental grounds, PVC remains the dominant polymer in the medical device sector. But the debate has spawned a new generation of materials that promise to augment, if not replace, PVC in a variety of applications.

Benjamin Lichtman

Polyvinyl chloride (PVC) has long enjoyed a privileged position in the medical industry. Flexible, transparent, economical, and easily sterilized, it has traditionally been the material of choice for such devices as IV and blood bags, tubing components, catheters, and inhalation masks. The polymer's strength, kink resistance, ease of fabrication, and weldability are often credited with its prevalence in such applications. Moreover, the material has also found a home in vinyl gloves, inflatable splints, mattresses, and hospital floorings.

But according to a recent report from Frost & Sullivan (London), although PVC continues to dominate the medical disposables market, "its share is gradually being eroded by polyolefin-based systems." The report concludes that the market share of PVC "has declined from 58.1% of unit shipments in 1995 to 55.5% in 1998." By 2005, the report predicts, PVC "will account for 47.7% of total unit shipments of plastic in medical disposables." The material's share of market revenues is projected to fall from 72.4% in 1998 to 66.2% in 2005.

Non-PVC tubing supplied by Rehau Ltd. is formed from such materials as silicone, EVA, and polyurethane, and is suited for use in pharmaceutical production, infusion kits, catheters, and wound drains.

The medical industry may be witnessing the death of a giant. Recent concerns about the safety and environmental consequences of using PVC in medical devices have threatened the polymer's position in the industry. Specifically, di-ethylhexyl phthalate (DEHP), the plasticizer that is most often used to soften PVC for flexible applications, is being investigated as a possible human carcinogen and endocrine disrupter. And environmentalists have raised concerns that the disposal of PVC by incineration may be a source of dioxin contamination.

The EU has been slow to take any regulatory action on these issues in the medical sector, although it did move to ban phthalates in certain children's toys in November 1999. The European Commission is currently conducting a horizontal, cradle-to-grave life cycle study of PVC in a variety of nonmedical applications, as well as a risk assessment study of the plasticizer DEHP. The results of the horizontal study are expected to be released by the end of 2000, but it is unlikely that the risk assessment study will be completed any time soon. In the meantime, DEHP remains the only recognized plasticizer for medical use according to the European Pharmacopoeia, and some readers may have noticed that until recently, the Commission's Berlaimont building in Brussels was covered in PVC to contain asbestos during renovations.

As might be expected, a lack of legislation has not prevented the market from reacting. In what is viewed as a harbinger of future market trends, major medical manufacturers including Baxter S.A. (Brussels), as well as purchasing groups such as Tenet Healthcare Corp. (Dallas, TX, USA), have recently signalled their intent to shift their product development and purchasing activities away from PVC in favor of alternative materials like polypropylene or polyethylene. These announcements have been lauded by groups such as Greenpeace International (Amsterdam) and Health Care Without Harm (HCWH; Falls Church, VA, USA), which seek the eventual replacement of PVC in the medical industry. HCWH has issued a report on the possible health risks of DEHP and petitioned US FDA to require labelling of medical products that contain the plasticizer.

Follow the Leader

Baxter's case has particular significance, because of the company's leading role in the IV therapy market. In April 1999, the firm signed a memorandum with a group of institutional shareholders stating, "Baxter is committed to exploring and developing alternatives to PVC products and to developing and implementing proposed timetables for substituting its current containers for intravenous solutions with a container that does not contain PVC."

The company stresses that the move away from PVC "has nothing to do with the unwarranted concern raised by activist groups regarding the safety of PVC." Nevertheless, many in industry view the move as a watershed development that will have a strong impact on material selection in the device sector. "Do we really have a choice?" asks a material and process engineer at a company that is a competitor of Baxter. "We don't have a decision to make; we need to make the move away from PVC," he says, predicting that within five to seven years his company will produce all of its IV bags with alternative materials.

"Baxter's decision was a milestone, and a big influence for other companies to think very seriously about [the PVC] issue," concurs Hermann Koch, product manager at Sengewald Verpackungen GmbH & Co. KG (Halle/Westfalen, Germany). Even before Baxter's announcement, Sengewald had begun to supply a coextruded, polypropylene film as an alternative to PVC in medical fluid bags. "In 1996, we felt that the PVC-free market would be very prosperous. We saw the potential for bag applications and we developed Propyflex," says Koch. The material recently garnered Sengewald a WorldStar 99 packaging award from the World Packaging Organization, a global association of industrial companies and scientific institutes.

It's Not Easy Being Green

Because medical PVC waste is a biohazard, it is typically disposed of through incineration. According to Koch, one of the advantages of materials like Propyflex is that their incineration is less detrimental to the environment than that of PVC. Because they do not contain chlorine, he notes, they do not contribute to dioxin emissions. "This is important," he adds, "since incineration often takes place at hospitals, which don't have all the environmental safety mechanisms of municipal waste incinerators."

Yet some scientists and industry observers argue that PVC is not the environmental culprit that it has been made out to be. "Our research has shown that in a normal municipal solid waste incinerator, removing PVC from the waste stream won't affect dioxin levels," says Stellan Marklund, professor of environmental chemistry at the University of Umeå in Sweden.

Jason Leadbitter, environmental and regulatory affairs manager at Hydro Polymers Ltd. (Newton Aycliffe, Co. Durham, UK), agrees. "The limiting step in dioxin formation in incinerators is not primarily determined by the amount of chlorine in the incinerator feed, but by plant hardware configuration and operating conditions," he says, adding that such parameters are regulated and controlled in Europe by the appropriate national agencies. Hydro supplies specialty PVC resin and compounds to the device sector and is reportedly the largest single-site PVC compounder in Europe.

A range of medical PVC compounds is offered by Hydro Polymers Ltd., including DEHP-free grades for specialized applications and compounds with frosted semiopaque finishes.

Birgitta Lindblom, environmental director at Baxter, concedes that if PVC is not properly incinerated, "you will have environmental problems because of the chlorine content." She adds that in the past, older European incinerators couldn't reach the necessary temperatures for proper disposal of PVC.

But, says Lindblom, incineration remains the disposal method of choice for PVC. "While PVC is enormously stable in landfills, this is a waste of energy," she says, noting that countries like Belgium and Sweden are using incinerators equipped with energy-recovery systems to convert heat output into usable energy. And because the raw material is so inexpensive, she explains, there is no good economic support for recycling. Ironically, she notes, "there is no material on the market that is as simple to recycle as PVC. In order to achieve the desired properties for medical applications, the alternative materials often use different laminates or coextrusions that are difficult to recycle."

A New Generation of Materials

The questions raised about the toxicity of PVC and the safety of its disposal have encouraged the development of innovative materials that attempt to sidestep these problems.

In addition to eliminating certain risks associated with PVC, alternative materials may also offer new benefits. Polyolefin bags, for instance, offer an improved water-vapour barrier when compared with PVC. This property is an advantage in the packaging of aqueous solutions, which normally require an extra overwrap layer on top of PVC.

"If there is a material with less risk, this should be considered," says Svend-Axel Laursen, managing director of Melitek a/s (Copenhagen, Denmark). "And if it is also stronger, equally or more transparent, environmentally friendly, and cost-effective, then it goes against all common sense to use the old material." Melitek supplies a flexible, transparent, medical-grade polyolefin alloy that reportedly offers improved strength characteristics when compared with PVC.

But some in industry view the replacement of PVC by new materials as a Pandora's box of unknown risks. According to Leadbitter, device manufacturers need not be concerned about the safety of PVC in medical applications. "A far bigger possible concern to such device manufacturers may be the development of non-PVC-based systems for which there may be far less known toxicological and human exposure data," he says.

Proponents of plasticized PVC argue that the material has been used in the medical industry for more than 40 years with no known adverse effects. Providing great support for this position, a panel convened by the American Council on Science and Health (New York City) and headed by former US surgeon general C. Everett Koop issued a report last year concluding that "DEHP in medical devices is not harmful to even highly exposed people...DEHP imparts a variety of important physical characteristics that are critical to the function of medical devices, and eliminating DEHP in these products could cause harm to some individuals."

EUCOMED, for its part, issued a position paper in November 1999, stating, "In view of the paramount importance of patient safety, any alternative should provide the same benefits as PVC, namely clarity, flexibility, and strength, and must be fully evaluated in terms of risk and performance. To date no alternative has been shown to demonstrate the numerous benefits of medical PVC." The EUCOMED position also makes reference to studies showing that DEHP actually prolongs the shelf life of red blood cells in PVC blood bags.

Considerations for Manufacturers

Even after weighing the important arguments concerning safety and environmental effects, manufacturers that are considering replacing PVC in their products must take a range of additional factors into account.

Cost is an immediate concern. While materials such as polyolefins are expected to become less expensive over time, most PVC alternatives on the market today carry premium price tags. Manufacturers should bear in mind, however, that some alternative materials can be used at lower thicknesses than PVC and may therefore be cost-competitive when downgauging is possible.

Production equipment is another consideration. Many alternative materials cannot be processed on existing equipment, effectively forcing manufacturers who abandon PVC to invest in new production lines. Some suppliers are forming partnerships with equipment manufacturers to develop solutions to this problem, which may involve new processing technologies, or retrofitting for existing machines.

According to some industry observers, this requirement for specialized production equipment effectively limits outsourcing, whereas with PVC, manufacturers had the option of outsourcing activities such as IV bag production. Colin Blass, in his report titled Polymers in Disposable Medical Devices—a European Perspective, points to a similar dilemma in compounding activities. The report, published by Rapra Technology Ltd. (Shrewsbury, Shropshire, UK), cites "the ease and simplicity with which a vast range of medical [PVC] compounds can be produced with tailor-made properties," and notes that some device manufacturers produce their own PVC medical compounds in-house. Not only does this approach result in lower costs, explains Blass, but it also ensures security of supply and allows manufacturers to produce small quantities on demand. It is too early to say whether the same scenario will develop for non-PVC polymers. Blass concludes, "This ability by the medical component manufacturer or OEM to control the PVC biomaterial chain is a strong argument for its continuing selection in competition with other medical polymers, which in almost every other case have to be sourced externally."

Finally, manufacturers should not overlook the regulatory burden in adopting a new material, says Deborah Spak, senior communications manager at Baxter. She notes that regulatory procedures to bring a new medical product to market could take anywhere from five to seven years.

The debate on the safety and environmental impact of PVC will doubtless continue, and various alternative materials are likely to coexist with PVC—at least for the time being. As the development of polyolefin materials continues and their prices decrease, industry observers expect to see a reduction in the market share of PVC.

Device manufacturers have more materials to choose from today than they have ever had before. Whether one material—or a combination of materials—will eventually replace PVC remains to be seen. Gavin Jones, technical marketing manager for the Medical Products Div. of Rehau Ltd. (Walford, Herefordshire, UK), says, "Lots of people are looking for that holy grail, and the first to find it will be a happy man or woman. Until then, it's a question of being smarter with what you've got."

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