Plastics are ubiquitous in everyday life because they are lighter, cost less than alternatives and are extremely useful. However, they may remain in the environment for years as they degrade into smaller and smaller pieces through wear and tear, unless properly disposed of or recycled. The smaller pieces of plastic (smaller than 5 mm) are called microplastics, while nanoplastics refer to extremely small pieces or particles of plastic (≤100 nm). Microplastics and nanoplastics comprise mixtures of polymers and functional additives, which may also include residual ‘impurities’. Functional additives include flame retardants, antistatic agents, surface modifiers, rheology control and anti-scratch additives, clarifiers and nucleating agents. For example, many people are familiar with the use of polystyrene in packaging and its ability to withstand impact and absorb shock.
Microbeads (deliberately produced microplastics) have been manufactured for about 50 years and it has only relatively recently been recognised that they can pass through water filtration systems and end up in the marine environment, posing a potential threat to aquatic life (United Nations Environment Programme, 2015). While some countries have banned exfoliating beads in facial and body scrubs and cosmetic products (The US in 2015, Canada in 2016, New Zealand in 2018, Sweden in 2019, Italy in 2020, UK in 2021, Korea in 2021) to reduce the deliberate manufacture of primary microplastics, they remain in cleaning products and fertilisers. Most microplastics (70–80%) are unintentionally formed through wear and tear, as well as the poor management of discarded plastics, known as secondary microplastics (Ali et al, 2023). Like other sectors, healthcare—and those working in healthcare—contribute to the ever-growing challenge of microplastics in the environment through the heavy use of disposable products.
Three review papers have outlined how microplastics are a major emerging threat to all ecosystems (atmosphere, soil, rivers and seas, and oceans), and how humans are exposed to microplastics via various routes with little information about how microplastics may impact human health and their potential toxic effects on organs. Ziani et al (2023) noted that the large volume of discarded personal protective equipment, particularly face masks made mainly of polypropylene during the COVID-19 pandemic, combined with poor waste management has worsened microplastic pollution. The review cites evidence that microplastics have been detected in many marine species in addition to in drinking water and various foods with animal studies finding plastic micro- and nanoparticles in the liver, spleen, heart, lungs, thymus, reproductive organs, kidneys and brain (indicating that plastic particles had crossed the blood–brain barrier). Ziani et al (2023) cautioned that microplastics were transporters of pollutants, which can interfere with normal biological processes and their long-term effects were unknown.
Lee et al's (2023) review was undertaken within the context of South Korean government's efforts to promote the effective management of microplastics. They noted that a mean concentration of 0.05 pieces/L of microplastics had been detected in 24 water-treatment plants receiving water from four South Korean rivers in 2017 and a mean concentration of 0.47 pieces/g microplastics had been detected in highly consumed marine products (including seafood) in 2020. This review set out how the population in South Korea was exposed to microplastics through direct ingestion, direct contact and inhalation, with increasing concern about the emerging evidence of the detrimental health effects of microplastics with exposure from infancy onwards.
Ali et al's (2023) review compiled the existing evidence relating to human exposure to microplastics through inhalation, ingestion and skin contact. Microplastics have been found in human stool samples because of ingestion through food, water and food packaging at varying levels, depending on age, sex, diet and lifestyle. Dermal exposure is considered least problematic, with the banning of microbeads in personal care products. Inhalation is one of the main routes of exposure and includes synthetic fibre particles with growing evidence of consequent respiratory tract damage. However, there is also evidence of the presence of microplastics in most body systems including cardiovascular, hepatic, renal, reproductive, nervous, immune, endocrine and muscular systems. Ali et al (2023) admitted that the current lack of standardisation of measurement is hampering the development of knowledge quantifying the extent of microplastics and their concentrations related to health risk. The first evidence of microplastics in human placenta was found in maternal, fetal and amniochorial membranes in 2020 (Ragusa et al, 2021) highlighting the imperative of minimising microplastics in the environment. The next World Environment Day is Thursday, 25 June 2025, which provides the opportunity to consider how healthcare plastic pollution can be reduced (Centre for Sustainable Healthcare, 2025). Where possible remember to: Reduce. Reuse. Recycle.