Plastic is one of humanities great inventions. Arguably the most versatile, durable and useful material to help our lives. It can be used to make things as diverse as a keyboard, a chair or bubble wrap. Plastic has become indispensable to make syringes, test tubes or to keeping food stay fresh for longer to feed more people. But because it's cheap to make, it is used for useless wrapping and many consumer-items for convenience, not necessity.
We use billions of tons of plastic for single, short-term use even when alternatives exist or plastic isn't needed. This has potential knock-on effects to our health and the environment.
In this review, we asked 28 experts to share the facts on plastic. Will plastic production ever become sustainable? Can all plastics be recycled? Are plastic fragments harmful for the environment or for us? And should you switch to glass containers for your packed lunch?
Here's what we found.
9 billion: Tons of plastics produced by humans.
400,000%: increase in plastic production since 1950.
79%: Plastic that ends up in landfills or in nature.
3.8%: Greenhouse gas emissions that are due to plastic.
190: Times more plastic produced today than in 1950.
100 million: Plastic bottles sold per minute.
12: Minutes that a single-use plastic bag is used for.
2030: Date for all plastic packaging to be reusable/recyclable in the EU.
9%: Plastic that is currently recycled.
883: Number of micro-plastic particles (1–5000 μm) consumed by adults each day
553: Number of micro-plastic particles (1–5000 μm) consumed by children each day
Bakelite was the first plastic ever created. In 1907 New York, a Belgium-born chemist Leo Baekeland, coined the term “plastic”. At the time, plastic just referred to the properties of the material (which could adapt to different shapes).
Today, we use the term mostly as a synonym for any polymer, that is, a chemical substance that is made up of hundreds or thousands of units of another, much smaller molecule. The polystyrene used in packaging and for insulation, for example, is a string of styrene molecules, which act as building-block pieces.
The PVC in your water pipes at home is just polyvinyl chloride. Plexiglass screens, which we have all seen a lot of over the last year, are made of polymethylmethacrylate (PMMA). Polymers can be natural too, though. Take natural rubber, which chemists call polyisoprene. Latex is made of this molecule, which certain trees produce to heal their wounds.
As plastic is an umbrella term for so many different materials and its definition has not always been clear, it is no surprise that several people are thought to have invented it. English engineer Alexander Parkes invented parkesine in 1856. That same year, American John Wesley Hyatt patented it as celluloid. The original goal was to come up with a replacement for ivory to make billiard balls (first world problems, anyone?). However, their discoveries were not met with much commercial success. By contrast, Baekeland’s bakelite, also known by the slightly more intimidating name of polyoxybenzylmethylenglycolanhydride, was the first plastic that was mass-produced and widely used. Manufacturers rapidly adopted the new material to make non-conducting parts of various devices — including Eriksson’s DBH 1001 telephones, which were sold for over three decades.
While the initial inventions are about two centuries old, we have only been mass-making plastics from the 50s. In 1969, Neil Armstrong planted a nylon (polyamide) flag on the Moon. Motorola developed the first mobile phones in the 70s. In 1982, the first artificial heart (made mainly of polyurethane) was implanted in a human.
You already know the rest of this story, really. Plastic production has sky-rocketed in recent years, as have warning signs that we need to rethink how we use plastic and manage waste. The world’s leading experts on plastic are calling for a more circular economy, where items are cycled in the production system rather than going straight to landfill (which most of the plastic waste does at the moment). More sustainable materials that are easier to recycle or have a longer lifespan are being developed. We are Homo sapiens, after all. Or Homo plasticus, some might say.
Can all plastics be recycled?
Okay, it sounds like we’d better be recycling all that plastic. There seems to be much room for improvement, as only about 9% of plastic is currently recycled. But can we really recycle all plastics? Not in the real world, say the experts.
Several factors make it hard for plastics to be recycled. First, good separation facilities are key for effective recycling - and these are not available everywhere. Experts also insist that products made of different components are challenging to recycle, and additives added to the polymers can also impede recycling. For these reasons, some say product design should improve if we want to facilitate recycling. “Plastics called thermosets (like those used in electronic circuits) do not melt, so they are much harder to recycle. The use of additives, like the ones used in electronic equipment (smartphones, tablets, computers), also hinders plastics' recyclability,” explains Dr Alethia Vázquez-Morillas, environmental engineer from Mexico.
Even when plastics can be recycled, they lose some of their properties in the process, becoming an overall poorer material. According to Dr Carla Elliff from the University of Sao Paulo, “there are basically two methods for recycling plastic: either cutting up the original plastic into small bits and melting them together into something new, or breaking down the polymer chain and restructuring the material in what is called chemical recycling. In both cases, the quality of the original plastic product decreases each time it goes through this process”. In other words, even recyclable polymers cannot really be recycled infinitely, but only a few times before being burned or ending up in landfill. For Dr Jill Bartolotta from Ohio State University, “plastic bottles will never be recycled into another plastic bottle. It will most likely become a bag or plastic clothing fabric. A plastic bag will become plastic lumber. There is no recycling option for plastic clothing or plastic lumber.”
So what can be recycled? Our World in Data, run by researchers from Oxford University, has a useful cheat-sheet about recycling plastics. Let us sum it up for you:
Widely recycled: Drink bottles, milk containers, shampoo and cleaning product bottles...
Often not recyclable: PVC pipes, bottle lids, furniture, houseware, ropes...
Rarely recycled: Plastic bags, plastic film, food wrappings, takeaway containers, plastic cutlery, diapers...
The good news is that alternatives are being rolled out to minimize use of single-use plastics. This includes a clear shift towards reusable carrier bags. Almost everyone we asked said that banning plastic bags is good for the environment.
These bags are usually used just for a few minutes, and are made of a type of plastic that is hard to recycle. They can also cause havoc for wildlife. “A lightweight plastic bag, if it escapes the waste stream can blow onto land, into rivers and into the ocean, where they can take potentially hundreds of years to degrade, depending on the conditions,” explains Dr Britta Denise Hardesty from the CSIRO in Australia.
According to Prof Calabrò, “substituting single-use plastic items with similar products made of biodegradable materials (e.g. cellulose straw or plates) or with reusable items (e.g. reusable shopping bags) is a good thing,” he writes. “If bans serve to obtain this they are welcome,” he adds.
However, several experts warn about 'greenwashing', marketing tactics to mislead the public into believing something is more sustainable than it really is. According to Dr Elliff, “any ban must be thoughtful of the context in which it is being implemented - meaning it should promote the use of alternatives, inform consumers and retailers, and be aware of biodegradable greenwashing that can take advantage of loopholes and make the ban effectively moot.”
Are biodegradable plastics better for the environment?
Experts were divided on the core part of this question. Many experts say 'biodegradable plastic' can also be 'greenwashing', while virtually all agreed that petrol-derived plastics are not and will not be sustainable. New polymers and blends are being synthesized currently to provide biodegradable alternatives they said. For instance, polyhydroxyalkanoates (PHAs) are a group of plastics produced by some forms of bacteria that are called to become the new generation of plastics as they are biodegradable and non-toxic. “Promising materials using waste from food production and biodegradable bioplastics are being developed,” writes Dr Sharon George from Keele University.
However, their ability to compete with traditional plastic is hampered by several drawbacks: their mechanical properties (and therefore their range of functionalities) are more limited and their production cost is higher. On top of that, they respond differently to temperature so they cannot be processed by the standard thermal techniques, and they degrade easily by heat.
Some of these materials are easier to degrade, but only in the right conditions. “Some biodegradable plastics require very specific conditions, for example, industrial composting conditions over 50C,” writes Dr George. It is only after these materials are fragmented by a combination of heat, water and enzymes that they can be degraded by microbes, she explains. According to Dr Vázquez-Morillas, “if compostable plastics go to landfills, where oxygen is lacking, they will not degrade readily. If, on the other hand, they are littered in the environment, there is no guarantee that they will find the required microorganisms, oxygen, and water needed for their biodegradation. Even if they find them, the process will not be immediate, and they could be ingested by different animals or cause other harmful effects.”
In this line, several experts are critical and warned against greenwashing, claiming that the term ‘biodegradable’ can be misleading. As biodegradable plastic does not necessarily biodegrade, it can be “even worse for the environment, because it leads to misunderstandings about the best ways to promote plastic recycling,” argues Dr Jacqueline Rutkowski from Brazil’s Interdisciplinary Centre for Studies and Research on Sustainability. For Dr Chris Wilcox from the CSIRO in Australia, biodegradable plastics are just “shorter lived pollution”.
Besides, “some bioplastics do not have the properties or economic value that traditional fossil-fuel based plastics do,” according to Dr Brian Johnston from the University of Wolverhampton, who argues that the main hurdle is making these polymers economically sustainable.
Are microplastics harmful to human health?
Plastic fragments have been found in plastic bottles and food packaging, so people are asking whether they can harm us when we ingest them. The focus on plastics vs microplastics is really one of size. If a human swallows a sharp shard of plastic that can cause havoc in their gastrointestinal tract, of course. But what about microplastics? While microplastics are just small fragments of plastic (<5 mm), the question of whether they are harmful to human health is a complex one.
Microplastic levels are on the rise in air, land and water, and there is evidence that we are constantly inhaling and ingesting them from our environment (including food, carpet fibers and many other sources). Each day, we inadvertently take up almost a thousand of these tiny fragments. And they can move around the body, once taken up. “If we ingest them, they will go through our digestive system, and if we inhale them, they will go to our respiratory system,” explains Dr Vázquez-Morillas.
Now, can they cause any harm to our organs? Several experts stress that microplastics are a rather recent issue, so we just haven’t had enough time to figure out any long term effects microplastics might have. Having said that, “there is evidence of plastic causing oxidative stress and inflammation in different human-derived cells,” writes toxicologist Josefa Domenech from Universidad Autónoma de Barcelona.
In addition, plastic additives, pathogens and pollutants can stick to microplastics and scientists worry about the potential impact of this. According to Dr Elliff, ”it might be the case that the actual plastics are not the greatest threat here but rather what these plastic particles carry with them.” However, “it would be challenging to isolate the effect of microplastics from that of the multiple chemical agents that we are in contact with every day,” admits Dr Vázquez-Morillas. Most of these data come from studying cultured cells or wild animals, but we still know very little about how microplastics may affect humans.
Still, indirect effects of microplastics on communities exposed to high levels of them are already a cause of concern. “Plastic pollution in beaches can reduce tourism, and thus compromise the livelihood of communities, and consequently their nutrition or access to healthcare,” explains chemist Joana Prata from the University of Aveiro.
Despite all the uncertainties, the experts agree on one thing — while scientists try to figure out whether and how microplastics can damage our health, avoiding its spread into the environment is our best shot.
Is it harmful to put plastic waste in landfill?
Once plastic waste is generated, it needs to be processed and managed. But what is the best way forward? And is it a bad idea to put plastic waste in landfill when it can not be recycled?
“The best option for plastic is limiting its use through substitution with other materials or by reuse”, writes Prof Paolo Calabrò, environmental engineer from Calabria University. “The second best is separate collection and recycling”, he adds. If these cannot be done, however, he defends disposal in controlled landfills as an option. “In a landfill the fossil carbon contained in the plastic is sequestered and basically cannot harm the environment,” according to Prof Calabrò. Release or leaching of harmful substances is unlikely “if the landfill is built and managed according to acceptable standards,” he explains. However, even if landfills are properly monitored, their capacity is limited so they are not a feasible long-term option. “Because [plastic] does not degrade, landfills soon fill up and new space is required to store new waste. Occupying new territory just to stock waste is definitely not a solution,” writes chemical engineer Dr Gian Claudio Faussone . “Where waste landfilling is not properly conducted, waste plastic can be dispersed into the environment over time, resulting in increasing pollution of land and sea”, he adds.
Scavenger animals such as gulls, who are regular visitors of landfills, are among those most harmed by plastic waste. Dramatic images of albatross that die after mistaking plastic for food have received much attention in recent years too. “Within seabirds, plastics can cause starvation, suffocation via blocking the air passage, strangulation and entanglement. In the case of bird species who are unable to regurgitate such as Albatross, plastics fill stomachs and cause the animals starvation which often leads to death”, explains Dr Sahar Seif from Carleton University. He explains that, in research done on gulls, plastic bits can affect their reproductive success as well.
Dr Manfred Fehr, engineer from the Federal University in Brazil writes that plastic is just one of the types of waste that ends up in landfill. “As it has no metabolism, it will happily stay there forever. It does not do any harm.” However, he argues that it is inappropriate to put plastic waste in landfill. “There are hundreds of ways to recirculate plastic material from one use to another. As long as it circulates in the economy, it generates revenue. So why throw it into a landfill?” Dr Fehr asks.
Is plastic production increasing globally? All the experts we asked said yes. Plastic production has increased exponentially in recent years and continues to do so across the world.
Are there any other uses for plastic waste? Yes, it could be used in construction — for instance, as a replacement aggregate for making concrete in substitution of sand.
Are plastic bag bans good for the environment? Yes. Bans or fees for plastic bags have reduced our use of single-use plastic bags, which are very harmful (particularly for marine wildlife). Compostable or reusable alternatives are better for the planet, but again, beware of greenwashing.
Is there a “plastic continent” in the Pacific? Not quite — it is more of a soup. The so-called Great Pacific Garbage Patch is the largest accumulation of ocean plastic in the world (which builds up between Hawaii and California due to the ocean currents).
Is it safe to reuse plastic water bottles? Yes, reused water bottles are just as safe as new ones. You do not have to worry about microplastics and leaching, but be sure to wash them thoroughly to keep them hygienic.
Is it safe to microwave food in plastic containers? Experts are split on this. Some containers are certified safe, but heat and fatty food help melt plastic. Some particles may then be released into your food, although it is unclear whether they would be harmful.
Is household recycling net beneficial to the environment?
Reduce, Reuse, Recycle
It is certainly better for households to recycle whenever possible, however there are greater environmental benefits to reduce where possible. For example, rather than accepting reusable bags at the supermarket, take your own; try and shop where there is less packaging for fruit, veg, and personal products. For household items such as carpet, furniture, electrical goods etc, when upgrading, explore the options for local reuse if they are in good working order, or recycling options with your local municipality.
Dr Rebecca Cunningham from University of Technology Sydney
We are producing more plastic than ever before, which puts pressure on wildlife and local communities across the world.
Plastic production from non-renewable sources is not sustainable, but work is being done to make them cheaper and more environmentally friendly.
Biodegradable plastics exist, but in practice they only biodegrade if they end up in the right composting facilities.
We likely consume nearly 1000 micro-plastic particles each day. The debate on the health effects of microplastics remains open. They spread easily and can be found in all sorts of body tissues, so experts are cautious about their potential harm.
Many plastic products cannot be recycled, and no plastic can be recycled infinitely. There is no single bullet to tackle plastic waste, but reducing and replacing plastic use remain the most effective actions.