Mesh Medical Device News Desk, June 13, 2016 ~ Using Plastic for Permanent Implants Is Not the Ideal Material
Mr. McGuire: I just want to say one word to you – just one word.
Ben: Yes sir.
Mr. McGuire: Are you listening?
Ben: Yes I am.
Mr. McGuire: ‘Plastics.’
Ben: Exactly how do you mean?
Mr. McGuire: There’s a great future in plastics. Think about it. Will you think about it?
Ben: Yes I will.
By the time young Dustin Hoffman was being schooled on his future in the 1967 film, “The Graduate,” the medical industry had discovered plastics.
Derived from the Greek word, “plastikos,” meaning to mold or form, plastics had an advantage over steel, ceramics and glass for medical use. Besides being pliable and implantable, plastics were cheap to produce and easy to dispose of avoiding cross-contamination in hospitals.
Derived from oil refineries generating many units of carbon, oxygen and hydrogen, by midcentury, production techniques allowed plastics to be molded into medical devices including those implantable – heart valves, stents, pacemakers, defibrillators, silicone implants, hip and bone implant components and hernia and pelvic mesh, to name a few.
In 2013, the global market for polypropylene (PP), a cheap commodity plastic, was about 55 million metric tons. PP has a wide range of applications. In the laboratory is can withstand the heat in an autoclave, so PP was easily adapted as suture material.
But problems with plastics are mounting.
While tests showed their endurance when interacting with oxygen, there was very little evidence of how they did constantly exposed to liquids, especially bodily fluids.
That’s a problem for 600,000 people worldwide who have pacemakers implanted and the 100,000 patients who receive defibrillators in the US each year.
When researchers in 2012 mimicked conditions inside the human body, they found materials began to break down within three to six years, including plastic used to coat cardiac leads that carry an electrical current from the battery to the heart. Water caused the plastic to age, soften or lose tensile strength, according to a study, published by the American Chemical Society.
Polypropylene has been used as hernia mesh since the 1950s and more recently implanted as a permanent implant in women with urine leakage or sagging pelvic organs. It too is now believed to change in the body in the presence of bodily fluids and heat with dire results for hernia and pelvic mesh recipients.
Initially marketed as inert, in 2011, Dr. Donald Ostergard, past president of the American Urogynecologic Society, published an article revealing information accumulating since the 1950s. Mesh is not inert, he wrote, the PP was able to incite an inflammatory response or foreign body reaction. Electron microscopy showed the deep cracks in the PP as it degrades in the body as well as shrinks 30 to 50 percent.
More than 100-thousand defective product lawsuits have been filed by women experiencing mesh complications.
What’s equally concerning, PP mesh implants are exposed to ethylene oxide (EtO), a low-temperature sterilization agent. EtO is regarded by the EPA as toxic and a carcinogenic and exposure is regulated by the EPA, and in the workplace, under the rules of the Occupational Safety and Health Administration (OSHA).
Two standards are supposed to assure the implant sterilization is safe for humans and the implants are biocompatible. But the ISO 10993 and United States Pharmacopoeia USP Class VI only go so far. According to Plastics in Medical Devices, Second Edition, “It would be possible to pass the USP Class VI test while still showing up as cytotoxic, mutagenic, hemolytic, or sensitizing in the biological testing.”
On May 24, 2016, a compromise deal in the European Union promised to step up surveillance of implanted medical devices. The deal, agreed to by the European Parliament and EU Council of Ministers, would limit the use of devices that contain carcinogenic, toxic, mutagenic or have hormone disrupting properties, including plastics.
Any device that is implanted and comes in direct contact with the human body containing those properties will be barred unless the proportions do not exceed 0.1 percent by weight. Consumers and doctors will be informed through strict labeling requirements.
The crackdown comes following a scandal in the EU in 2011 when a French manufacturer used industrial grade silicone in breast implants.
In the EU, a central database will list all devices on the market that are implanted.
The U.S. has yet to establish a national database for adverse events when plastic medical devices go wrong. ##