Published by Advanced Industrial and Engineering Polymer Research

Available online 29 June 2021

the original link https://www.sciencedirect.com/science/article/pii/S2542504821000348

Author: Blessy Josepha(a), Jemy Jamesb(b), Nandakumar Kalarikkala(a), Sabu Thomasac(a,c)

a.International and Inter University Centre for Nanoscience and Nanotechnology, Mahatma Gandhi University, Kottayam, 686560, Kerala, India

b.WiTec, Bengaluru, 560094, Karnataka

c.School of Energy Materials, Mahatma Gandhi University, Kottayam, 686560, Kerala, India

Received 9 April 2021, Revised 13 June 2021, Accepted 16 June 2021, Available online 29 June 2021.

Highlights

Recycling medical wastes into value added products.

Internal collection system at each source.

Sorting using spectroscopic techniques.

Choice of sterilization technique matters.

Sterilization wraps and other common plastic materials can be effectively recycled.

Abstract

A large amount of non-infected plastic wastes are being generated at the healthcare facilities all over the world. However, only a small fraction is recycled. Conventionally, the used plastics are either disposed in landfills or inadequately incinerated. These practices impart an adverse effect on our environment. Plastics are indispensable part of the medical sector owing to their high versatility. The outbreak of Covid-19 clearly showed the growing demand for single use plastics. Hence, completely avoiding plastics can be challenging at this point of time. Recycling of plastics is undoubtedly a solution to solve the crisis of plastic pollution. Medical plastic recycling is limited mainly due to difficulties involved in sorting or cleaning. Recycling medical plastic wastes is possible only through proper coordination between healthcare sector and recycling industries. New recycling technologies are to be adopted in a sustainable manner. Moreover, the plastics used in medical applications should be designed such that recycling is possible. This review highlights the downside of medical wastes and discusses the recycling potential of commonly used medical plastics.

Keywords

medical recycling; single use plastics; incineration; pyrolysis

1. Introduction

Plastics have made our life easier. From house hold items to medical equipment, plastics are integral part of our life. They have revolutionized industries mainly because of their ease of processing, transparency and cost effectiveness[1,2]. They can be designed with tailored properties and resist environmental degradation with time. Medical plastics are designed for specific applications in healthcare industry. Plastics can be processed into any shape or size and can be easily functionalized for imparting desired chemical or functional properties. Medical instruments which were made of steel, ceramics or glass are low replaced with plastics which proved to be cost effective and durable. Plastics are widely explored in medical disposable manufacturing owing to the spread of infections associated with non-disposable materials. They are light weight and can be blended with additives or fillers to fine tune their flexibility or surface properties. To use plastics for biomedical applications, care should be given in selecting appropriate plastic material, their chemical or thermal properties, sterilization potential and its durability.

The mismanagement of medical plastics is causing serious health issues and can be a reason for long term pollution. Worldwide there have been huge demand to reduce plastic consumption. Removing or reducing plastic is a challenging task; for instance this can be done from our house hold applications. Regarding medical industry, removal of plastic is still a herculean task to achieve. The unprecedented outbreak of COVID 19 resulted in tons of medical plastic wastes. Single use plastics offer immense health benefits in terms of maintaining a sterile environment, thus has become part our daily life especially during this pandemic. There has been a dramatic demand for personal protective equipment (PPE). PPE which includes masks, safety goggles, face shields, hair covers etc. are all made of plastics like polyethylene terephthalate (PET), polycarbonate, low density polyethylene etc.[3]. The commonly used respirators contain PP non-woven fibres. Although, plastics provides great sort of protection against deadly virus, single use plastics can cause detrimental impacts on the environment. According to World Health Organization (WHO), 89 million masks, 30 million gowns, 1.59 million goggles and 76 million gloves are required every month due to the pandemic condition. The pandemic outbreak has also led to large number of medical waste generation which also include plastics. The average waste generated in King Abdullah University hospital, Jordan was estimated to be ten times greater than the average generation rate during the regular operational days of the hospital (14.16 kg/patient/day while considering 95 infected patients) during 25days period[4]. This data clearly shows how difficult it is to manage the dramatic increase in medical waste during the time of pandemic. Studies report that corona virus remains in the surface of plastic for more than 72hours[5,6]. Recovery of plastics in such cases can be problematic.

In Asia, the total medical waste generated is estimated to be around 16,659.48 tons/day[7]. Around 5.9 million tons of waste are generated per year from healthcare facilities across US and 1.7 million tonnes of this are comprised of plastics [8]. 25% of this is comprised of plastic materials. Millions of tonnes of plastic enter sea every year according to reports and is detrimental to marine life. Research says if plastics dumped into the ocean are recycled, it can save the lives of up to 1 million sea creatures per year[9]. This shows the desperate need for recycling plastics. By taking effective recycling measures we are not only reducing plastic pollution, but we are saving energy as well as greenhouse emissions. There has been a growing concern over the disposal of medical wastes. The hospital wastes are source of potential infections. Usually, medical wastes are treated in incinerators which might not be effectively designed. Moreover, this has raised the problem of air pollution. Hence alternative means to dispose medical plastics is still a major factor that needs to be addressed.

Introducing sustainability into medical plastics have been a matter of discussion over recent times. Several studies focus on the necessity of using biodegradable or bio plastics. Bioplastics are environmental friendly and are used for applications ranging from medical implants to drug delivery devices. The main source of bio plastics are biomass like agricultural crops. Some of the common examples include polylactic acid (PLA), starch, cellulose etc. Bioplastics are also produced by microorganisms, algae etc. PHA is a commonly studied biodegradable plastic produced by microrganisms. Microalgae is considered as a potential source of biomass for bio plastic production. They can be also combined with other polymers or petroleum plastics to produce bio plastics having enhanced mechanical properties[10]. Polymers like PLA can take about one year to degrade in soil. However, PLA can be recycled to produce lactic acid[11]. Thermal and mechanical recycling of PLA has also been reported[11,12]. Bioplastics have properties comparable to petroleum based counter parts hence they should be produced in large scale to meet the growing industrial needs. More studies should focus on the cost effective production of bio plastics which have the potential to replace the single use non-degradable plastics widely employed in medical sectors. The design of medical grade plastics should be geared towards recyclable and cost-effective strategies.

Sustainability should be a matter of concern for everyone including the regulatory bodies and common man. Currently, not much data are available on the recycling of medical plastics although recycling is an efficient waste management strategy. This review aims to detail the need for recycling medical plastics, current recycling techniques and their limitation within the framework of available data.

2. Medical plastics: Types and properties

Medical devices have been part of human race since thousands of years. During the initial part of history, metal was the major material being used to prepare medical devices. Later on by the late 1920s’, ceramic also started to be a material to be used, especially for orthopaedics, bone and dental implants. Sometime later, glass came in to the picture where in it was used in tubing and storage. But some of the issues associated with these materials, like heavy weightiness, higher cost of manufacturing, lower biocompatibility, paved the way for plastics to be used in the medical care. Even though, scientist have been experimenting with plastics since the early 19th century, plastics started revolutionizing the medical industry only by the middle of the 20th century.

The global market size of medical plastics valued around USD 22.8 billion in 2019 and is expected to reach USD 31.7 billion by 2024, at a CAGR of 6.8% according to a report by Markets and Markets. Plastics have revolutionized the medical field mainly due to its resistance to corrosion, heat, chemicals, light weight nature and most importantly cost effectiveness. It can withstand several sterilization cycles and different types of sterilization. Plastics are used in varied applications involving MRI casings, surgical tools replacing ceramics and other metals, implants, bedpans etc. (Table 1).