I’m confident that plastic waste in the environment is not a good thing, but I confess that in my personal list of things to worry about–economic, environmental, hot war in Europe–I’m not sure how high to rank the issue. For background, the OECD has just published “Global Plastics Outlook: Economic Drivers, Environmental Impacts and Policy Options” (February 2022, freely readable online, although you need to pay for a PDF or hard copy).

The report points out at the start that the benefits of plastics are also the source of the environmental concerns:

The first manufactured plastic, Parkesine, was developed from cellulose in the mid-19th century and found applications as a clothing waterproofer and as synthetic ivory. Almost half a century later, Bakelite became the first truly synthetic plastic to be developed. However, it was not until 1950 that global plastics production began its unprecedented growth, which has seen it expand 230-fold to the present day. The rapid growth of plastics is due to their unique properties: high strength-to-weight ratio, high moldability, impermeability to liquids, resistance to physical and chemical degradation, and low cost. They can easily substitute for other materials (such as glass, metal, wood and natural fibres) in a wide range of applications.
However, some of the desirable qualities of plastics are also their key limitations. Plastics are highly resistant to physical and chemical degradation, which also means that they can persist as waste in the environment for decades or even centuries.

Use of plastics has been rising substantially, as has plastic waste.

Globally, the annual production of plastics has doubled, soaring from 234 million tonnes (Mt) in 2000 to 460 Mt in 2019. Plastic waste has more than doubled, from 156 Mt in 2000 to 353 Mt in 2019. After taking into account losses during recycling, only 9% of plastic waste was ultimately recycled, while 19% was incinerated and almost 50% went to sanitary landfills. The remaining 22% was disposed of in uncontrolled dumpsites, burned in open pits or leaked into the environment. … Almost two-thirds of all plastic waste comes from applications with lifespans of less than five years: packaging (40%), consumer products (12%) and textiles (11%). Only 55 Mt of this waste was collected for recycling, but 22 Mt ended up as a recycling residue that needed further disposal.

How bad is plastic waste for the environment? The main focus of the OECD report is on tracking and forecasting production and waste flows of plastic around the world, and the report devotes relatively little space to this issue. Indeed, the report is forthright that the existing knowledge on environmental/health costs of plastic still has real gaps: “A major challenge posed by plastics in the environment is the considerable uncertainty about the magnitude of the damage. Firstly, there are still important gaps in the current understanding of the plastic health-biosphere links. Secondly, there are important uncertainties surrounding the quantities of plastics entering the environment and their accumulation.”

With that reality duly noted, here’s a sample of the concerns and evidence from the report:

In aquatic environments, the most visible negative effects on marine wildlife are the entanglement of marine organisms in floating plastic debris and increased mortality following the ingestion of macro and microplastics by marine species such as mussels, turtles, fish and sea birds. At least 690 wildlife species, as well as coral reefs, are known to be affected (Gall and Thompson, 2015[65]). However, the negative consequences of plastics extend beyond these first order impacts. Microplastics have been documented in the digestive tract of several types of mussels and fish destined for human consumption (Lusher, Hollman and Mendoza-Hill, 2017[66]). Thus, the ingestion of seafood contaminated with microplastics has
also been identified as a potentially substantial exposure pathway for humans.

Microplastic contamination is not exclusive to marine environments – it has also been documented in freshwater and terrestrial environments, as well as in food and beverages, such as tap water, bottled water and beer (Kosuth, Mason and Wattenberg, 2018[67]; Mintenig et al., 2019[68]). Humans are also exposed to microplastics by inhaling airborne particles and fibres, and microplastics have been reported both in indoor and outdoor environments (Gasperi et al., 2017[69]; Allen et al., 2019[61]). The main studies of human health impacts of airborne microplastics have looked at exposure to non-exhaust road traffic emissions

Plastics may also act as a sink and transportation media for chemicals and persistent organic pollutants (POPs), which accumulate on the surface of plastics while in seawater. Adsorbed chemicals found on sampled plastic debris include PCBs, PAHs, DDE (a breakdown product of DDT) and trace metals (Engler, 2012[70]; Teuten et al., 2007[71]). Plastic fragmentation may enhance leaching of chemical substances to the surrounding environment. Nanoplastics are of particular concern because their small size allows them to potentially be transferred to tissues or cells (SAPEA, 2019[72]).

Furthermore, marine plastic leakage has substantial economic costs for coastal communities due to potential negative impacts on fishing and tourism. Plastics can affect the sustainability of fisheries, while plastic leakage on beaches deters visitors, causing financial distress to local communities reliant on tourism. Beaumont et al. (2019[73]) estimate the economic costs of the loss of marine ecosystem services to be around USD 3 300 per tonne of marine plastic per year.

None of this is good, of course, and it certainly makes a prima facie case for focusing on some ways to reduce plastic waste. But the reader will also notice that evidence on the spread of plastic waste is more clear than evidence on harms to the size or health of marine populations, or to human health. And of course, substituting other materials for plastics or recycling plastics has costs, too.

The report discusses various options, like developments in recycling. I was discouraged to learn that efforts to create plastics which biodegrade naturally, which seemed relatively promising to me a few years ago, have not gained much traction and now seem to be faltering.

Biodegradable plastics gained some popularity with the idea they would degrade in the natural environment into carbon dioxide, water and biomass. They are currently used for packaging, agriculture, horticulture, textiles and consumer goods. Global production capacities of biodegradable plastics was 1.2 Mt in 2019 or less than 0.3% of total plastics (Crevel, 2016[4]; European Bioplastics, 2019[5]). Innovation in biodegradable plastics, measured by the number of patented inventions, doubled between 1995 and 2017. Between 2013 and 2017, 228 patent families for biodegradable plastics were granted every year (Dussaux and Agrawala, forthcoming[2]). However, since 2013, the speed of innovation has
slowed down, probably because the environmental impact of compostable plastics has become controversial due to the issues related to biodegradation in natural environments

The concerns over biodegradable plastics seem to come in two forms. One is that biodegrading requires certain conditions, which often aren’t present: “Biodegradation also requires optimal conditions, such as the concentration of enzymes, strains of microorganisms, temperature, pH value, humidity, oxygen supply and light. These optimal conditions are rarely present in natural environments …” In other words, when you put “biodegradable” plastics in landfill, they don’t actually break down. The other issue is that some biodegradable plastics have extra ingredients added, like certain metals, to help the breakdown process–but the metals themselves can be a source of environmental concerns, too.

For some previous posts on plastics, see: