We’ve all learned in Wire & Cable 101 that poly(vinyl chloride) (PVC) reigns supreme for its low cost, high temperature ranges, and multipurpose capabilities. PVC can be easily manipulated using various additives which contain halogens and phthalates to enhance certain properties like flame resistance, temperature performance, or flexibility. However, when choosing wire and cable components for medical devices, is it time for manufacturers to pick up a new textbook that takes into account the various negative consequences of PVC?

Fig. 1 – Standardized Environmental Questions for Medical Products.

The downsides to using PVC insulation and jacketing on wire and cable components have been rising to the forefront in terms of their environmental and biological risks lately, especially in Europe. When PVC plasticizers are thrown into the mix, used to soften material for greater flexibility, the negative consequences are exacerbated even more. The risks to using PVC components in medical devices can be broken down into three major health consequences: patient, environment, and system.

Patient Health

If we take a look at the history of Diethylhexyl phthalate (DEHP) in medical devices, it has been the long-standing primary plasticizer used, due to its low-cost ability to increase flexibility in medical applications. DEHP is frequently found in electrical cables, as well as blood bags and medical tubing. Since 2002, concerns over the use of plasticizers have emerged, as the harmful elements may migrate from the device to the human body, resulting in patient exposure to those most vulnerable. Plasticizers are not chemically bound to PVC, thus exposure to such chemicals may pose significant health risks to patients such as the elderly, newborns, and those with weakened immune systems.

In 2007, the Scientific Committee on Emerging and Newly Identified Health Risks (SCENIHR) conducted a study on the harmful effect of PVC-plasticizers, including DEHP used in medical devices, and the consequences to using such chemicals in medical devices. An opinion paper can be found here http://ec.europa.eu/health/ph_risk/committees/04_scenihr/docs/scenihr_o_014.pdf . While varying levels of exposure incur greater effects, DEHP elements can have harmful effects on reproductive organs, the liver, and overall alreadyweakened immune systems. The Amendment 2007/47/EC to the Medical Device Directive initiated the labeling requirement for devices containing phthalates (of which plasticizers are made). However, today there is the increasing push to eliminate PVC-plasticizer based components altogether.

What does this mean for your medical device? To avoid the potential risks of plasticizers and phthalate-based components, medical device manufacturers have taken proactive steps to eliminate PVC from their devices in favor of alternate insulations. The SCENIHR is set to revisit the DEHP debate and provide a new opinion on the use of plasticizers in medical devices, in light of increased scientific evidence on its effects over the past five years since their last opinion on the topic. It is no doubt the regulations and limits to PVC-plasticizer usage are sure to become stricter in the coming years. When designing new medical devices for our aging population, why not take the proactive approach to a healthier design?

Environmental Health

Fig. 2 – Size comparison of PVC vs. MPPE insulation.

The medical device marketplace has also shifted its focus when it comes to designing a product that will not harm the environment after it has reached the end of its life. On top of the negative consequences a device can initiate onto its patient, components that contain PVC or XLPE can release harmful halogens such as fluorine, chlorine, and bromine into the environment when disposed. When the wire and cable components of a device typically are made with these types of insulations, the use of such highly reactive elements increases the environmental risk and thwarts recyclability efforts.

With new RoHS regulations put into place as of January 2, 2013, to include medical devices and monitoring equipment, what is a manufacturer to do? PVC insulations are the go-to compound for low-cost and physical properties, but size, weight, and now environmental limitations have put PVC under the magnifying glass for scrutiny. Alternatives to PVC, such as thermoplastic elastomers, are being thrown into the mix as a safe, and performance-enhancing alternative that will meet both RoHS and Waste Electrical and Electronic Equipment (WEEE) Directives. Several companies within the medical device market are already ahead of the curve. Since Autumn 2011, at least six large health care purchasing organizations have promoted a “Standardized Environmental Questions for Medical Products” guide to selecting products made with a greener design in mind, which can be found at https://practicegreenhealth.org/gsc/standardized . (See Figure 1)

Medical device manufacturers including Philips Healthcare and Medtronic have increased their focus on eco-friendly designs that work towards decreasing waste, increasing recyclability, and eliminating hazardous substances.

Surprisingly enough, the costs to replacing PVC in medical devices are far outweighed by the benefits of such alternatives on the market. Companies such as Alpha Wire have developed compounds with superior dielectric properties that allow for a reduced wall thickness, resulting in a smaller, lighter, and tougher wire and cable. The company’s modified polyphenylene ether (MPPE) insulation is successfully used on both wire and cable products, is 100% recyclable, and contains no PVC, halogens, or phthalates. Advantages to using a PVC alternative are increased two-fold when the manufacturer can also decrease the size, weight and outgassing of its internal components. (See Figure 2)

System Health

If you aren’t convinced of PVC’s harmful effects in medical devices up until this point, there remains one last detriment to using this insulation powerhouse. A recent study released by Teknor Apex material science company in October 2013 determined that PVC and plasticizers alongside non-PVC components in devices can migrate when they come into contact with each other, resulting in softening, cracks, and other defects in the system. Their study tested ten different types of plasticizers, including DEHP, and determined it may have adverse effects on non-PVC plastics.

The first thought towards a solution for this might be to eliminate the plasticizers and switch to a rigid PVC compound for the device components. However, doing so would take a step backwards in the design evolution of medical devices. In a 2010 report published by the United Nations Department of Economics and Social Affairs, our population is predicted to increase to more than nine billion by 2050, with more than 15% of the total population aged 60 and older. Medical devices are transitioning to the home, where they are smaller, more portable, and simpler to use. Similarly, as new markets emerge worldwide, medical devices need to accommodate areas where the conventional doctor’s office may be sparce. Traditional PVC-based components will not survive in a competitive marketplace steering towards smaller and lighter designs.

Regulations and negative study results have scientists and officials coming at PVC from all sides, demanding a better solution. Plasticizers are generally turned to for their performance-enhancing benefits such as flexibility, but they are no longer the only solution.

With new advancements on the market that provide PVC alternatives, and increasing regulations handed down from the EU and other regulatory agencies, the trend towards a healthier and greener medical device design is not going to be a passing phase. Design engineers will need to place emphasis on a component’s environmental and health implications as much as its performance overall within the application. By steering designs away from plasticized components, companies can be on the forefront of innovation and ahead of Directive amendments that are sure to come.

This article was written by Kaitlin Janne, Corporate Marketing Specialist, Alpha Wire, Elizabeth, NJ. For more information, Click Here " target="_blank" rel="noopener noreferrer">http://info.hotims.com/49741-160.