Decoding Medical-grade Plastics: Exploration & Selection

TAGS:  Medical    

The medical industry needs special polymer grades that comply with the standards of the healthcare system. The global market demand for these plastics is expected to increase in the upcoming years.

Medical-grade plastics play a huge role in healthcare — from live-saving devices to simple pill bottles. Thus, these materials are expected to possess some desirable properties such as:

• biocompatibility,
• non-permeability,
• sterilization resistance,
• lightweightness, and
• durability

Funds are being regularly allotted by the government and regulatory bodies for the research of medical plastics. Innovations in recycling and navigating the problems associated with it are being addressed.

This article will ease your selection of medical plastics grades as we take you through the following aspects:

1. What are medical-grade plastics?
2. Global Market Growth of Medical Plastics
3. Which polymers are key in medical applications?
4. What properties are associated with medical plastics?
5. Common Sterilization Methods for Medical-grade Plastics
6. Are regulatory standards imposed on medical-grade plastics?
7. Can medical plastics be recycled?

What are medical-grade plastics?

Medical-grade plastics are a special type of polymers used in healthcare. These materials are engineered to meet strict needs for medical use. For example, being safe for the body, able to be sterilized, functionality, performance, and durability.

Medical plastics must not induce adverse reactions (toxicity, irritation, or others...) on coming in contact with the human body. They also must withstand repeated sterilization by heat, chemicals, or radiation.

Some common medical plastics are:
Polyethylene (PE)	Polypropylene (PP)	Polyvinyl chloride (PVC)
Polystyrene (PS)	Polycarbonate (PC)	Polyetheretherketone (PEEK)
Polymethylpentene (PMP)	Acrylic (PMMA)	Acrylonitrile butadiene styrene (ABS)

With more focus on sustainability, the medical industry is using more eco-friendly options. This shift is driven by the necessity to follow stringent regulations. It also reduces the ecological footprint of healthcare practices.

Global Market Growth of Medical Plastics

The market for medical-grade plastics has witnessed significant growth in recent years. This is driven by the following aspects:

• Advancements in medical technology
• An aging population
• An increasing demand for innovative healthcare solutions. For example, wearable medical devices, disposable medical supplies, implantable devices, etc.

The global medical plastics market size was estimated at 52.9 billion USD in 2023. It is expected to grow at a compound annual growth rate (CAGR) of 7.4% from 2024 to 2030.¹

U.S. Medical Plastics Market Research¹
(Source: Grand View Research)

Key Polymers in Medical Applications

Polyethylene (PE)

Polyethylene is the most common plastic used in medical devices. Its inertness, flexibility, toughness, affordability, & ease of processing make it well-suited for:

•  Fluid handling systems, blood and IV bags, catheters and syringes
•  Tubings, lab equipments, surgical trays, etc.

High-density polyethylene (HDPE) and ultra-high molecular weight polyethylene (UHMWPE) grades are predominantly used.

Polypropylene (PP)

Polypropylene is appreciated for its high-temperature resistance, low density, chemical resistance, and economical cost. It is ideal for:

•  Syringes, housings, vials, test tubes, and medical packaging
•  Urine bags, filters, and autoclavable trays
•  Surgical masks and gowns

Polypropylene is also used as sutures due to its high tensile strength.

Polyvinyl Chloride (PVC)

PVC is intrinsically clear, rigid, and can be easily sterilized. It is the material of choice for:

•  Fluid containers, blood bags, and tubings
•  Oxygen masks
•  Dialysis equipment

Plasticizers are added to make flexible PVC, which is used for gloves and catheters. However, there are concerns over plasticizer leaching and environmental issues of PVC disposal.

Polystyrene (PS)

Polystyrene is optically clear, resistant to chemicals, and inexpensive. It is frequently used to make:

•  Petri dishes and vials
•  Diagnostic instrument housings
•  Tissue culture trays
•  Protective packaging

High-impact polystyrene (HIPS) provides greater toughness for surgical instrument trays, emesis basin, etc.

Polycarbonate (PC)

Polycarbonate combines optical clarity, dimensional stability, high impact resistance, and inherent sterilizability. It is widely used for:

•  Dialyzers and incubators
•  Surgical tools
•  Orthodontic appliances and lenses

It is also used in transparent medical equipment housings that must withstand frequent high-temperature sterilization.

Acrylic (PMMA)

Polymethyl methacrylate, also known as acrylic, offers transparency, UV resistance, and weatherability at low cost. It is used for:

•  Anesthetic masks, incubators, and viewing windows
•  Transparent medicalware and lenses
•  Dentures and orthopedic implants

PMMA is also popular for bone cement.

Acrylonitrile Butadiene Styrene (ABS)

ABS is an economical, rigid thermoplastic with good dimensional stability. It is chemically resistant and easier to process than PC. ABS finds use in:

•  Medical housings, handles, and fittings
•  Instrument panels
•  Structural components

It can be sterilized by radiation, chemicals, and moderate heat.

Polyetheretherketone (PEEK)

PEEK is an advanced thermoplastic with excellent chemical resistance, thermal stability, and biocompatibility. It is used for:

•  Trauma implants
•  Spinal fusion cages
•  Other high-performance medical applications
•  Catheter bushings

Polymethylpentene (PMP)

PMP is a semi-crystalline polymer with high tensile strength, purity, and transparency. It offers exceptional resistance to sterilization methods. PMP is used for:

•  Films
•  Autoclavable medical trays and boxes
•  Other applications needing repeated or aggressive sterilization
•  Orthopedic implants

Main Properties Associated with Medical Plastics

Biocompatibility: Ensuring safe body response

Biocompatibility refers to the ability of a material to perform with an appropriate host response when used for its intended medical purpose. Thus, medical plastics must not be toxic, injurious, or immunogenic when in contact with bodily tissues or fluids.

Some key considerations for the biocompatibility of medical plastics include:

• Cytotoxicity — The material should not have toxic effects on living cells. Leachables and extractables must be below hazardous levels.


• Sensitization — The plastic should not cause an allergic response when implanted. Sensitization testing is done using animal models.


• Irritation and inflammation — Medical plastics should not cause irritation, swellings, lesions, or inflammatory responses in the body. These are evaluated through skin irritation studies.


• Hemocompatibility — Medical plastics must undergo a hemolysis test. If the device involves blood contact, the plastic must not induce thrombosis, embolism, rupture of red blood cells, etc.


• Carcinogenicity — The materials must not promote cancerous tumors when implanted. Two-year animal carcinogenicity studies are conducted.


• Genotoxicity — The plastics must not damage cell DNA or cause mutations. Tests like the Ames test can identify genotoxins.


• Sterilization residuals — After sterilization, the plastics should not retain toxic residues. They must not leach out later.

Non-permeability: Resisting diffusion of substances

Non-permeability refers to the ability of the plastic to act as an effective barrier. This prevents the diffusion of various substances through it. This is crucial for those plastics used in fluid handling, containment, and delivery applications.

Key aspects of non-permeability:

• Water permeability — Medical tubing, fluid bags, catheters, etc., must not allow water transmission or absorption from medical devices. This can impact the performance and properties of medical devices.


• Gas permeability — Oxygen masks, anesthetic equipment, and IV tubing should not permit gas diffusion. This could lead to concentration changes. Select all medical plastics with low gas permeability.


• Chemical permeability — Drug-eluting devices rely on plastics that diffuse active agents at a controlled calibrated rate. They should be impermeable to other chemicals.


• Microbial permeability — The plastic matrix should act as a barrier against microbial transmission. Microporosity compromises sterility.


• Leachable permeability — Plastics must not diffuse out of the material into the fluids or surrounding tissue. Examples of plastic components that can leach are additives, fillers, plasticizers, etc.

Factors influencing permeability include crystallinity, crosslinking, polarity, fillers used, and molecular structure. High-density and crosslinked plastics offer lower permeability.

Resistance to sterilization: Preventing infection transmission

Medical devices and equipment need to be repeatedly sterilized by hospitals. This helps to prevent infection transmission. Medical-grade plastics must withstand frequent sterilization through heat, radiation, steam, and chemicals. There must be no change in visual appearance, physical properties, mechanical performance, etc.

Key considerations include:

• Heat resistance — Plastics are subjected to repeated autoclave or dry heat sterilization cycles. They must retain their properties even after these sterilization processes. For example, tensile strength, impact resistance, and other mechanical properties.


• Radiation resistance — Gamma or e-beam radiation can degrade polymers. This can happen through chain scission, oxidation, and crosslinking. Suitable plastics should resist high sterilization doses.


• Chemical resistance — Chemical sterilants should not cause degradative effects over time. For example, cracking, hydrolysis, leaching, swelling, etc.


• Sterilant absorption — Residual-absorbed sterilants should not leach from the plastics and cause toxicity. Aeration/extraction procedures may be needed.


• Appearance — Sterilization should not significantly change the appearance of plastics. For example, optical clarity, reflectivity, or color, or cause yellowing/chalking.

Plastics can resist damage during repeated sterilization necessary for safe medical use. This can be achieved with the presence of additives. For example, antioxidants, stabilizers, radio-opacifiers, etc.

Lightweightness: Enabling easier handling

Lightweight plastics help reduce fatigue and improve ergonomics for medical professionals. They do so by making devices and equipment easier to handle and carry. For patients, lightweight plastics in medical products minimize the weight burden. For example, in prosthetics and mobility aids.

Some key aspects are as follows:

• Low density — Medical plastics like polyethylene, polypropylene, acrylic, and ABS have densities between 0.85 - 1.2 g/cm³. This is lower than metals like steel (8 g/cm³).


• High strength-to-weight ratio — Medical plastics can be formulated and engineered for high strength and stiffness relative to their low mass. This allows downgauging and weight reduction.


• Easier handling — Devices made from lightweight plastics reduce wrist strain. They are more comfortable for extended surgical procedures requiring manipulation.


• Portability — Portable equipment with plastic frames and housings is easier to transport and use. For example, wheelchairs, patient monitors, etc.


• Ergonomics — Customized plastics make handheld devices easier to use with less fatigue issues. For example, handles, grips, and housings.


• Patient comfort — Lightweight plastics are less burdensome for patients to carry. For example, plastic prosthetics, braces, and implants.

Durability: Maintaining performance throughout the lifetime

Medical devices made from plastics need to maintain performance throughout their expected lifetime. This is despite their routine cleaning, handling, transportation, and sterilization stresses.

Key aspects of durability include:

• Tensile strength — Plastics used for load-bearing applications need high strength and stiffness. This helps to withstand mechanical forces during use without permanent deformation or cracking.


• Creep resistance — Medical parts like plastic tubing and device housings undergo repeated flexing. The materials should be fatigue-resistant.


• Impact and abrasion resistance — Good toughness and abrasion resistance help external components. For example, plastic enclosures withstand bumps and scratches during routine use.


• Dimensional stability — Plastics should maintain close dimensional tolerances over time. This should be without any warpage. For example, precision fittings and components.


• Chemical resistance — Medical plastics need to resist cleaners, disinfectants, and bodily fluids. They must not crack or expand/contract excessively. Select medical-grade plastics with good chemical resistance.


• UV/weathering resistance — Plastic devices must retain properties even upon being exposed outside. For example, light, humidity, and other environmental conditions in storage and use. Select medical-grade plastics with good weather resistance.

To aid in the selection process, a table outlining specific applications and the most common polymers used, along with their key properties, is provided below:

Applications	Common Polymers	Key Properties
Medical Packaging	PE, PP, PVC	Non-permeability, resistance to sterilization
Surgical Instruments	PP, PC, ABS	Biocompatibility, durability, resistance to sterilization
Implants	PE, PC, ABS, PEEK	Biocompatibility, lightweightness, durability
Drug Delivery Systems	PVC, PP, PC	Non-permeability, compatibility with pharmaceuticals
Diagnostic Components	PS, PC, ABS	Transparency, durability
Dental Devices	PMMA, PC	Biocompatibility, transparency, resistance to sterilization
Wearable Medical Devices	PE, PC, ABS	Lightweightness, durability, biocompatibility
Transparent Components	PMP	Transparency, low density, chemical resistance
High-temperature Applications	PEEK	High-temperature resistance, chemical resistance, strength

Applications and Key Features of Common Polymers Used in Medical Industry

Common Sterilization Methods for Medical-grade Plastics

Ensuring medical plastics can withstand sterilization is important in maintaining the sterility of medical devices. Let’s review some common sterilization methods:

Steam sterilization (Autoclaving)

Autoclaving is a widely used sterilization method. It involves steam and high pressure. Plastics selected for autoclaving must resist:

• deformation,
• discoloration, and
• degradation under these conditions

Radiation-resistant plastics are crucial at places where gamma or electron beam radiation is used for sterilization. Effective for heat and moisture-resistant plastics like polypropylene.

Effect of steam sterilization on properties

Tensile strength and impact resistance: Some plastics may experience a reduction in tensile strength and impact resistance after repeated autoclave cycles. Understanding the temperature limits and duration of exposure is crucial in selecting plastics that can withstand these conditions.

Effect of steam sterilization on performance

Material stability: Heat sterilization can affect the stability of certain materials, potentially leading to changes in the physical and mechanical properties of the plastic. Proper selection ensures that materials maintain their original characteristics even after exposure to high temperatures.

Radiation sterilization

Radiation sterilization uses ionizing radiation, like gamma rays or electron beams. This helps to eliminate various microorganisms from medical devices and equipment. The radiation disrupts the DNA of these organisms. This prevents them from reproducing and thus eliminating their ability to cause harm. This is typically done at ≤ 50 kGy. However, some plastics can withstand higher doses. It generates no toxic residuals and is environment-friendly.

Effect of radiation sterilization on properties

Chain scission and crosslinking: Ionizing radiation, such as gamma rays or electron beams, can induce chain scission or crosslinking in polymers. The extent of these effects depends on the type of polymer and the radiation dose. For example, polyethylene may become cross-linked, affecting its flexibility.

Effect of radiation sterilization on performance

Material integrity: Radiation-resistant plastics are essential to ensure that the material maintains its structural integrity and performance after exposure. This is particularly crucial for medical devices that require reliable and consistent mechanical properties.

Ethylene oxide (EtO) sterilization

EtO sterilization utilizes a gaseous form of ethylene oxide (EtO). This eliminates microorganisms on medical devices under controlled conditions of:

• temperature,
• humidity, and
• pressure

The EtO gas penetrates the packaging and device. This leads to the alkylation of the DNA or RNA of microorganisms. Thus, it prevents them from reproducing and rendering them inactive. It requires lengthy aeration to remove toxic residuals. Limited for thermoplastics due to residue retention and flammability risks.

Effect of EtO sterilization on properties

Material swelling: Ethylene oxide gas can lead to swelling in certain plastics. This may impact the dimensional stability and overall structure of the material.

Effect of EtO sterilization on performance

Residue removal: Ethylene oxide sterilization requires thorough aeration to remove toxic residuals. It is important to consider the potential impact of these residuals on the material's performance and biocompatibility.

Chemical sterilization

Chemical sterilization involves using liquid or gaseous chemicals with antimicrobial properties. These chemicals help to destroy microorganisms on medical devices. It needs extensive validation of efficacy and material effects. Various chemicals are employed, but the focus here is on those suitable for plastics:

• Oxidizing agents: They target microbial cell walls and membranes, causing oxidative damage. For example, hydrogen peroxide, peracetic acid, and ozone.
• Halogens: They disrupt essential cellular processes of microorganisms. For example, chlorine dioxide and hypochlorous acid.

Effect of chemical sterilization on properties

Chemical compatibility: Plastics must be selected based on their compatibility with the specific sterilizing chemicals used. Some plastics may be susceptible to degradation or changes in properties when exposed to certain chemicals.

Effect of chemical sterilization on performance

Material integrity: The impact of chemical sterilization on material integrity should be carefully evaluated to ensure that the plastic maintains its performance characteristics without compromising safety.

Regulatory Standards Imposed on Medical-grade Plastics

Several regulations and standards control the use of plastics in medical applications. This enables to ensure patient safety. Medical device manufacturers must comply with a complex framework before their plastic products are marketed. This includes compliance with laws, guidelines, and approval processes. Key areas of regulatory oversight include:

• FDA device classifications
• ISO standards for biocompatibility evaluation and requirements for validated and verified materials
• USP Class VI-grade plastics mandates where direct patient contact exceeds 24 hours

Successfully navigating the regulatory landscape is crucial for companies. This helps to bring safe and effective medical products containing plastics to market.

FDA classifications and approval process for medical devices

The U.S. Food and Drug Administration (FDA) classifies medical devices into three categories². This is based on the level of risk they pose to patients as depicted in the below table. Select suitable medical plastics compliant with US FDA.

Class I/Low Risk Class I devices are considered low-risk and are subject to general controls. Examples include bandages, dental floss, and non-powered surgical instruments.

Class II/Moderate Risk Class II devices require special controls to provide reasonable assurance of safety and effectiveness. This category includes devices like infusion pumps, surgical drapes, and diagnostic devices.

Class III/High Risk Class III devices undergo stringent scrutiny, requiring pre-market approval to ensure safety & efficacy. Examples are life-supporting equipment, implantable & certain diagnostic devices.

ISO standards for biocompatibility testing

International Organization for Standardization (ISO) standards³ provide guidelines for assessing the biocompatibility of medical devices. Medical plastics must be compliant with ISO to ensure safety and performance criteria.

➤ ISO 10993 — This is the key set of standards for biological evaluation of medical devices. It lays out test methods to assess cytotoxicity, sensitization, irritation, systemic toxicity, etc. Select medical plastics compliant with ISO 10993.

➤ ISO 10993-5 — Specifies approaches for evaluating the cytotoxicity of device extracts. In vitro methods include agar overlay, elution assays, and MEM extract assays using cell lines.

➤ ISO 10993-10 — Deals with skin irritation and sensitization testing. Methodologies include animal testing as well as reconstructed human epidermis models.

➤ ISO 10993-11 — Guides systemic toxicity testing of materials. This is through injection, implantation, or other routes of administration into animals.

➤ ISO 18562 — Evaluates biocompatibility of 3D printing materials used in medical applications. It is a newer standard.

➤ ISO 20795 — Covers requirements for the safe use of powders for medical 3D printing made of polymers like PA, TPU, PEKK, etc.

➤ ISO 10993-13 — Specifies identification, quantification, safety evaluation, and control of potential leachables in medical plastics.

➤ ISO 14971 — Focuses on risk management principles. These principles assess, control, and monitor the hazards of medical devices.

USP Class VI passing

USP Class VI is a biocompatibility standard mandated by the United States Pharmacopeia. It is required for plastics used in medical devices that involve patient contact exceeding 24 hours. This includes implants, long-term catheters, etc. Class VI testing is extensive. It involves systemic toxicity, implantation effects, hemocompatibility, pyrogenicity, and more.

Passing Class VI indicates the highest grade of biocompatibility - suitable for permanent or long-term exposure. Lower USP Classes (I to V) are for plastics used in medical devices with limited contact. Class VI compliance is also required by the FDA as part of device submission for plastics that have contact exceeding 24 hours.

ISO 10993 has replaced some Class VI protocols but USP testing is still referenced due to historical requirements. Medical molders and extruders get specific grades certified as USP Class VI compliant based on testing. The Class VI certification facilitates device approval and assures manufacturers and patients of biocompatibility for long-term exposure.

Can medical plastics be recycled?

Recycling of used medical plastics is rarely done. This is due to the concerns over contamination from body fluids and maintaining sterility. There are protocols for the disposal of medical plastics as biohazardous/regulated medical waste. However, certain unused or pre-sterilized medical devices do enter the recycling stream.

The plastics are granulated and reprocessed under strictly controlled conditions. Applications are limited to non-medical products. Although recycled HDPE is sometimes used for new boxes, crates, pallets, trash cans, park benches, etc.

Sustainability efforts are underway to segregate and recover clean medical plastics for recycling. For instance, recycling programs for returned IV bags and tubing. But cost, logistics, and stringent quality demands hinder widescale adoption as yet. The potential risks mandate very high standards to consider recycling used medical plastics.

Addressing challenges in recycling biohazardous medical plastics

Enhanced sorting technologies

Innovations in sorting technologies aim to improve the segregation of biohazardous medical plastics. There are advanced sorting systems utilizing artificial intelligence and machine learning. They can distinguish between contaminated and non-contaminated materials more accurately.

Controlled disassembly processes

Controlled disassembly processes allow the separation of different components within medical devices. This could be instrumental in efficiently extracting and recycling plastics. Thus, it minimizes the risks associated with biohazardous materials.

Single-use device design optimization

Initiatives promoting the optimization of single-use medical device designs are gaining traction. Product design needs to be reimagined with recycling in mind. This enables manufacturers to create devices that are easier to disassemble and recycle. Thus, it reduces the challenges posed by biohazardous waste.

Chemical decontamination advances

Research is ongoing to explore advanced chemical decontamination methods. They can neutralize biohazardous materials without compromising the integrity of the plastics. This could open avenues for safer recycling processes in the future.

Sustainable disposal programs

Closed-loop systems

Some medical institutions are exploring closed-loop systems. Here, medical plastics are collected, processed, and recycled within a controlled environment. These systems aim to mitigate contamination risks. They ensure that biohazardous medical plastics are handled responsibly.

Industry collaboration and standards

Collaborative efforts within the medical and recycling industries are being fostered. It establishes standards and best practices for the recycling of medical plastics. Initiatives like the Healthcare Plastics Recycling Council (HPRC) are creating guidelines. They address the unique challenges associated with recycling biohazardous medical plastics.

Governmental and regulatory support

Incentives and regulations

Governments and regulatory bodies are recognizing the importance of sustainable practices in healthcare. Future policies may include incentives to medical institutions and manufacturers. They would encourage them to adopt environmentally responsible disposal and recycling methods.

Research funding

Research funding for developing efficient recycling technologies for biohazardous plastics will increase. This support can catalyze breakthroughs in recycling processes. They will ensure both sustainability and compliance with healthcare safety standards.

Technological advancements in biohazardous waste management

Smart tracking and identification

Integration of smart tracking and identification technologies will be implemented in the future. This will help to trace the entire lifecycle of medical plastics. This will in turn ensure proper disposal. Tracking of recycled materials back into new medical devices will be facilitated.

Robotics and automation

Robotics and automation could play a significant role in handling biohazardous medical plastics. Automated systems with advanced sensors and safety features can streamline the recycling process. It can minimize the risks associated with human intervention.


Advancements in innovative technologies make the future of medical plastic recycling look promising. It can create a more sustainable and environmentally conscious healthcare industry. The collective efforts of the medical and recycling communities positively drive the way biohazardous medical plastics are managed and recycled.

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