Plastics for all
The first National Plastics Exposition opened its doors in New York City in April 1946. Post-war recovery and a sustained global economic expansion were starting, and people were enthralled by plastics. They were cheap, durable, versatile and convenient, and no one asked or cared if they were also biodegradable. The petroleum with which to make them was abundant, and chemical engineers were highly creative. There seemed no end to the benefits that plastics would bestow on ordinary people. Since then, 10 billion tonnes or so of plastic have been made. Highly resistant to biological degradation, virtually all of that legacy plastic is still with us in the global environment, including inside us.
A new relationship with nature
On World Environment Day we consider issues that are harming the global environment, Earth’s living systems, and human wellbeing. Some have their own special days in the UN calendar, such as threats to biodiversity, wetlands, wildlife, forests, Mother Earth, oceans, and mountains. So on 5 June the focus is on key issues that might otherwise be neglected. One is the fast-growing problem of plastic pollution. How to end it was the focus of an international conference hosted by UNESCO in Paris from 29 May to 2 June 2023, with the aim of negotiating a new treaty by 2024. This is vital because plastics, microplastics and nanoplastics have now penetrated every part of the biosphere. Their effects as pollutants are diverse and dangerous, so plastics now have a key role in defining a new era in humanity’s relationship with nature.
A tsunami of plastic
Total plastic production is now over 400 million tonnes annually, having doubled since 2005 and likely to double again by mid-century. Less than a tenth of total production is recycled, and half of all plastic products are designed to be used only once. Among other things, these account for a million plastic bottes sold every minute worldwide, and five trillion plastic bags used each year. About three-quarters of all plastic is discarded as waste, mostly into land-fill, but nearly 25 million tonnes annually end up in lakes, rivers and seas. Of these, about 11 million tonnes enter the oceans each year, getting tangled up in marine ecosystems or joining one of the great floating garbage patches that are fed by rotating oceanic currents or gyres.
Ruining the view
There are few more depressing sights than rubbish in what would otherwise be a lovely place. Plastic garbage especially, since we know it will never decay naturally and will stand forever as a sign of human grubbiness. Tips spilling down slopes from beauty-spot car parks; skeletons of trapped shrews in old bottles; ragged bags hanging from twigs; bones, feathers and cigarette lighters in sea-bird nests where the chicks should be; yoghurt pots, shopping bags and fishing lines wafting to and fro in coral reefs; spangles of multicoloured fragments in the tissues of jellyfish. Even if plastics were totally harmless to living systems, which they are not, the heart rebels at the carelessness and ugliness of it all.
Microplastics and nanoplastics
Rather than decaying organically, plastics break down into ever-smaller fragments. Microplastic particles, ranging in size from a millionth to five thousandths of a metre (1 μm to 5 mm), move easily in water and air and have been detected in ecosystems and organisms across the world. Globally, the great majority of of drinking water and sea salt samples now contain microplastics, for example, and fragments of polyethylene terephthalate, polyethylene, polystyrene and polypropylene have all been detected in human blood. Far smaller nanoplastic particles (0.001-1 μm) are also out there in vast quantities, and it is known that the smaller they are the more easily they enter plant and animal tissues. But nanoparticles are hard to study and very hard to filter from effluents, such as from recycling facilities where plastics are made into pellets. One modern re-processing facility in the UK, for instance, was found to be releasing hundreds of tonnes of small micro- and nanoplastic particles annually, as they passed straight through the installed filters. The result is that the biosphere is now awash in tiny plastic fragments, all doing unknown but potentially severe harm to everyone and everything.
Feral toxins
The main components of plastics are carbon polymers, but on average they also contain about 6% of additives such as plasticisers, flame retardants, stabilisers and pigments, as well as various processing residues. Over 13,000 chemicals are involved in making plastics, of which barely more than half have been tested for hazardous properties and nearly half of those are dangerous. These are linked to a wide range of acute, chronic and inter-generational toxic effects, including specific organ toxicity, various types of cancer, genetic mutations, reproductive toxicity, developmental toxicity, endocrine disruption and ecotoxicity. Many also persist in the environment, accumulate in food chains, and are able to move to over long distances. Thus plastic garbage poses dangers locally, downstream, and far away, right up to the Arctic where persistent organic pollutants condense in the cold and enter the food chain, all the way up to orcas and polar bears. Few waste recyclers have full information on these hazards, or the technology to manage them, so recycling can release toxins and recycled plastics may even contain concentrated poisons.
A plastic shroud for Mother Earth
Many scientists believe that we have now entered a geological period called the Anthropocene, the ‘new age of humanity’. They expect that one day a layer of rock dated to about 1950 and only a few millimetres deep will exist all over the world. It will be rich in the fragments and residues of agriculture, industry, fire and war, and most obviously plastics. Below this layer will be abundant and diverse fossils, revealing the richness of life in the pre-human biosphere. But for centimetres above it there will be few fossils other than those of chickens, rats and people. It will stand out to future observers in the same way as the thin dark layer, rich in iridium, that marks the Chicxulub meteor strike 66 million years ago. This caused such global devastation that it killed the non-avian dinosaurs, pterosaurs, ichthyosaurs and many other kinds of life. In this sense, humanity’s rise over 11,700 years since the last ice age has been truly meteoric. The plastic stones of the future will surely mark us as the champion litterbugs of planet Earth.
Turning off the plastics tap
UN Member States have now agreed to seek a treaty on ending plastic pollution. Many technical solutions are available to reduce the use of virgin petroleum-based polymers, and allow much more plastic to be recycled safely. Biodegradable alternatives also have a key role. But ensuring uptake of these solutions will be hard, and livelihoods will have to be safeguarded. A system-change approach has been proposed, in which markets for reusable and alternative products, and the business case for recycling, would all be strengthened. More investment would also be needed in collecting and processing legacy plastics. But the costs would be relatively low, especially if the economic benefits of reduced pollution and new business opportunities are considered. Thus there is a viable path to making plastic pollution a thing of the past. To join it, treaty negotiators must find ways to harmonise international action, while building synergies to create major policy shifts and practical changes. And then the hard work of global clean up can begin in earnest.
© Julian Caldecott