Monique Retamal, University of Technology Sydney; Elsa Dominish, University of Technology Sydney; Nick Florin, University of Technology Sydney, and Rachael Wakefield-Rann, University of Technology Sydney
We all know it’s wrong to toss your rubbish into the ocean or another natural place. But it might surprise you to learn some plastic waste ends up in the environment, even when we thought it was being recycled.
Our study, published today, investigated how the global plastic waste trade contributes to marine pollution.
We found plastic waste most commonly leaks into the environment at the country to which it’s shipped. Plastics which are of low value to recyclers, such as lids and polystyrene foam containers, are most likely to end up polluting the environment.
The export of unsorted plastic waste from Australia is being phased out – and this will help address the problem. But there’s a long way to go before our plastic is recycled in a way that does not harm nature.
Plastic waste collected for recycling is often sold for reprocessing in Asia. There, the plastics are sorted, washed, chopped, melted and turned into flakes or pellets. These can be sold to manufacturers to create new products.
The global recycled plastics market is dominated by two major plastic types:
polyethylene terephthalate (PET), which in 2017 comprised 55% of the recyclable plastics market. It’s used in beverage bottles and takeaway food containers and features a “1” on the packaging
high-density polyethylene (HDPE), which comprises about 33% of the recyclable plastics market. HDPE is used to create pipes and packaging such as milk and shampoo bottles, and is identified by a “2”.
The next two most commonly traded types of plastics, each with 4% of the market, are:
polypropylene or “5”, used in containers for yoghurt and spreads
low-density polyethylene known as “4”, used in clear plastic films on packaging.
The remaining plastic types comprise polyvinyl chloride (3), polystyrene (6), other mixed plastics (7), unmarked plastics and “composites”. Composite plastic packaging is made from several materials not easily separated, such as long-life milk containers with layers of foil, plastic and paper.
This final group of plastics is not generally sought after as a raw material in manufacturing, so has little value to recyclers.
China banned the import of plastic waste in January 2018 to prevent the receipt of low-value plastics and to stimulate the domestic recycling industry.
Following the bans, the global plastic waste trade shifted towards Southeast Asian nations such as Vietnam, Thailand, Malaysia, and Indonesia. The largest exporters of waste plastics in 2019 were Europe, Japan and the US. Australia exported plastics primarily to Malaysia and Indonesia.
Australia’s waste export ban recently became law. From July this year, only plastics sorted into single resin types can be exported; mixed plastic bales cannot. From July next year, plastics must be sorted, cleaned and turned into flakes or pellets to be exported.
This may help address the problem of recyclables becoming marine pollution. But it will require a significant expansion of Australian plastic reprocessing capacity.
Our study was funded by the federal Department of Agriculture, Water and the Environment. It involved interviews with trade experts, consultants, academics, NGOs and recyclers (in Australia, India, Indonesia, Japan, Malaysia, Vietnam and Thailand) and an extensive review of existing research.
We found when it comes to the international plastic trade, plastics most often leak into the environment at the destination country, rather than at the country of origin or in transit. Low-value or “residual” plastics – those left over after more valuable plastic is recovered for recycling – are most likely to end up as pollution. So how does this happen?
In Southeast Asia, often only registered recyclers are allowed to import plastic waste. But due to high volumes, registered recyclers typically on-sell plastic bales to informal processors.
Interviewees said when plastic types were considered low value, informal processors frequently dumped them at uncontrolled landfills or into waterways. Sometimes the waste is burned.
Plastics stockpiled outdoors can be blown into the environment, including the ocean. Burning the plastic releases toxic smoke, causing harm to human health and the environment.
Interviewees also said when informal processing facilities wash plastics, small pieces end up in wastewater, which is discharged directly into waterways, and ultimately, the ocean.
However, interviewees from Southeast Asia said their own domestic waste management was a greater source of ocean pollution.
The price of many recycled plastics has crashed in recent years due to oversupply, import restrictions and falling oil prices, (amplified by the COVID-19 pandemic). However clean bales of PET and HDPE are still in demand.
In Australia, material recovery facilities currently sort PET and HDPE into separate bales. But small contaminants of other materials (such as caps and plastic labels) remain, making it harder to recycle into high quality new products.
Before the price of many recycled plastics dropped, Australia baled and traded all other resin types together as “mixed plastics”. But the price for mixed plastics has fallen to zero and they’re now largely stockpiled or landfilled in Australia.
Several Australian facilities are, however, investing in technology to sort polypropylene so it can be recovered for recycling.
Exporting countries can help reduce the flow of plastics to the ocean by better managing trade practices. This might include:
improving collection and sorting in export countries
checking destination processing and monitoring
checking plastic shipments at export and import
improving accountability for shipments.
But this won’t be enough. The complexities involved in the global recycling trade mean we must rethink packaging design. That means using fewer low-value plastic and composites, or better yet, replacing single-use plastic packaging with reusable options.
The authors would like to acknowledge research contributions from Asia Pacific Waste Consultants (APWC) – Dr Amardeep Wander, Jack Whelan and Anne Prince, as well as Phil Manners at CIE.
Monique Retamal, Research Principal, Institute for Sustainable Futures, University of Technology Sydney; Elsa Dominish, Senior Research Consultant, Institute for Sustainable Futures, University of Technology Sydney; Nick Florin, Research Director, Institute for Sustainable Futures, University of Technology Sydney, and Rachael Wakefield-Rann, Research Consultant, Institute for Sustainable Futures, University of Technology Sydney
Australia’s wetlands are home to a huge range of stunning flora and fauna, with large snakes often at the top of the food chain.
Many wetlands are located near urban areas. This makes them particularly susceptible to contamination as stormwater, urban drainage and groundwater can wash metals — such as arsenic, cadmium, lead and mercury — into the delicate ecosystem.
We know many metals can travel up the food chain when they’re present in the environment. So to assess contamination levels, we caught highly venomous tiger snakes across wetlands in Perth, and repurposed laser technology to measure the metals they accumulated.
In our new paper, we show metal contamination in wild wetland tiger snakes is chronic, and highest in human-disturbed wetlands. This suggests all other plants and animals in these wetlands are likely contaminated as well.
Urban growth and landscape modification often introduces metals into the surrounding environment, such as mining, landfill and waste dumps, vehicles and roadworks, and agriculture.
When they reach wetlands, sediments collect and store these metals for hundreds of years. And if a wetland’s natural water levels are lowered, from agricultural draining for example, sediments can become exposed and erode. This releases the metals they’ve been storing into the ecosystem.
This is what we suspect happened in Yanchep National Park’s wetland, which was supposed to be our “clean” comparison site to more urban wetlands. But in a 2020 study looking at sediment contamination, we found this wetland had higher levels of selenium, mercury, chromium and cadmium compared to urban wetlands we tested.
And at Herdsman Lake, our most urban wetland five minutes from the Perth city centre, we found concentrations of arsenic, lead, copper and zinc in sediment up to four times higher than government guidelines.
In our new study on tiger snake scales, we compared the metal concentrations in wild wetland tiger snakes to the concentrations that naturally occurs in captive-bred tiger snakes, and to the sediment in the previous study.
We found arsenic was 20-34 times higher in wild snakes from Herdsman Lake and Yanchep National Park’s wetland. And snakes from Herdsman Lake had, on average, eight times the amount of uranium in their scales compared to their captive-bred counterparts.
Tiger snakes usually prey on frogs, so our results suggest frogs at these lakes are equally as contaminated.
We know for many organisms, exposure to a high concentration of metals is fatally toxic. And when contamination is chronic, it can be “neurotoxic”. This can, for example, change an organism’s behaviour so they eat less, or don’t want to breed. It can also interfere with their normal cellular function, compromising immune systems, DNA repair or reproductive processes, to name a few.
Snakes in general appear relatively resistant to the toxic effects of metal contamination, but we’re currently investigating what these levels of contamination are doing to tiger snakes’ health and well-being.
Snakes can be a great indicator of environmental contamination because they generally live for a long time (over 10 years) and don’t travel too far from home. So by measuring metals in older snakes, we can assess the contamination history of the area they were collected from.
Typically, scientists use liver tissue to measure biological contamination since it acts like a filter and retains a substantial amount of the contaminants an animal is exposed to.
But a big problem with testing the liver is the animal usually has to be sacrificed. This is often not possible when studying threatened species, monitoring populations or working with top predators.
In more recent years, studies have taken to measuring metals in external “keratin” tissues instead, which include bird feathers, mammal hair and nails, and reptile scales. As it grows, keratin can accumulate metals from inside the body, and scientists can measure this without needing to kill the animal.
Our research used “laser ablation” analysis, which involves firing a focused laser beam at a solid sample to create a small crater or trench. Material is excavated from the crater and sent to a mass spectrometer (analytical machine) where all the elements are measured.
This technology was originally designed for geologists to analyse rocks, but we’re among the first researchers applying it to snake scales.
Laser ablation atomises the keratin of snake scales, and allowed us to accurately measure 19 contaminants from each tiger snake caught over three years around different wetlands.
Our research has confirmed snake scales are a good indicator of environmental contamination, but this is only the first step.
Further research could allow us to better use laser ablation as a cost-effective technology to measure a larger suite of metals in different parts of the ecosystem, such as in different animals at varying levels in the food chain.
This could map how metals move throughout the ecosystem and help determine whether the health of snakes (and other top predators) is actually at risk by these metal levels, or if they just passively record the metal concentrations in their environment.
It’s difficult to prevent contaminants from washing into urban wetlands, but there are a number of things that can help minimise pollution.
This includes industries developing strict spill management requirements, and local and state governments deploying storm-water filters to catch urban waste. Likewise, thick vegetation buffer zones around the wetlands can filter incoming water.
Anyone with even a passing interest in the global environment knows all is not well. But just how bad is the situation? Our new paper shows the outlook for life on Earth is more dire than is generally understood.
The research published today reviews more than 150 studies to produce a stark summary of the state of the natural world. We outline the likely future trends in biodiversity decline, mass extinction, climate disruption and planetary toxification. We clarify the gravity of the human predicament and provide a timely snapshot of the crises that must be addressed now.
The problems, all tied to human consumption and population growth, will almost certainly worsen over coming decades. The damage will be felt for centuries and threatens the survival of all species, including our own.
Our paper was authored by 17 leading scientists, including those from Flinders University, Stanford University and the University of California, Los Angeles. Our message might not be popular, and indeed is frightening. But scientists must be candid and accurate if humanity is to understand the enormity of the challenges we face.
First, we reviewed the extent to which experts grasp the scale of the threats to the biosphere and its lifeforms, including humanity. Alarmingly, the research shows future environmental conditions will be far more dangerous than experts currently believe.
This is largely because academics tend to specialise in one discipline, which means they’re in many cases unfamiliar with the complex system in which planetary-scale problems — and their potential solutions — exist.
More broadly, the human optimism bias – thinking bad things are more likely to befall others than yourself – means many people underestimate the environmental crisis.
Our research also reviewed the current state of the global environment. While the problems are too numerous to cover in full here, they include:
About 1,300 documented species extinctions over the past 500 years, with many more unrecorded. More broadly, population sizes of animal species have declined by more than two-thirds over the last 50 years, suggesting more extinctions are imminent
about one million plant and animal species globally threatened with extinction. The combined mass of wild mammals today is less than one-quarter the mass before humans started colonising the planet. Insects are also disappearing rapidly in many regions
a halving of live coral cover on reefs in less than 200 years and a decrease in seagrass extent by 10% per decade over the last century. About 40% of kelp forests have declined in abundance, and the number of large predatory fishes is fewer than 30% of that a century ago.
The human population has reached 7.8 billion – double what it was in 1970 – and is set to reach about 10 billion by 2050. More people equals more food insecurity, soil degradation, plastic pollution and biodiversity loss.
High population densities make pandemics more likely. They also drive overcrowding, unemployment, housing shortages and deteriorating infrastructure, and can spark conflicts leading to insurrections, terrorism, and war.
High-consuming countries like Australia, Canada and the US use multiple units of fossil-fuel energy to produce one energy unit of food. Energy consumption will therefore increase in the near future, especially as the global middle class grows.
Then there’s climate change. Humanity has already exceeded global warming of 1°C this century, and will almost assuredly exceed 1.5 °C between 2030 and 2052. Even if all nations party to the Paris Agreement ratify their commitments, warming would still reach between 2.6°C and 3.1°C by 2100.
Our paper found global policymaking falls far short of addressing these existential threats. Securing Earth’s future requires prudent, long-term decisions. However this is impeded by short-term interests, and an economic system that concentrates wealth among a few individuals.
Right-wing populist leaders with anti-environment agendas are on the rise, and in many countries, environmental protest groups have been labelled “terrorists”. Environmentalism has become weaponised as a political ideology, rather than properly viewed as a universal mode of self-preservation.
Financed disinformation campaigns against climate action and forest protection, for example, protect short-term profits and claim meaningful environmental action is too costly – while ignoring the broader cost of not acting. By and large, it appears unlikely business investments will shift at sufficient scale to avoid environmental catastrophe.
Fundamental change is required to avoid this ghastly future. Specifically, we and many others suggest:
abolishing the goal of perpetual economic growth
revealing the true cost of products and activities by forcing those who damage the environment to pay for its restoration, such as through carbon pricing
rapidly eliminating fossil fuels
regulating markets by curtailing monopolisation and limiting undue corporate influence on policy
reigning in corporate lobbying of political representatives
educating and empowering women across the globe, including giving them control over family planning.
Many organisations and individuals are devoted to achieving these aims. However their messages have not sufficiently penetrated the policy, economic, political and academic realms to make much difference.
Failing to acknowledge the magnitude and gravity of problems facing humanity is not just naïve, it’s dangerous. And science has a big role to play here.
Scientists must not sugarcoat the overwhelming challenges ahead. Instead, they should tell it like it is. Anything else is at best misleading, and at worst potentially lethal for the human enterprise.
Corey J. A. Bradshaw, Matthew Flinders Professor of Global Ecology and Models Theme Leader for the ARC Centre of Excellence for Australian Biodiversity and Heritage, Flinders University; Daniel T. Blumstein, Professor in the Department of Ecology and Evolutionary Biology and the Institute of the Environment and Sustainability, University of California, Los Angeles, and Paul Ehrlich, President, Center for Conservation Biology, Bing Professor of Population Studies, Stanford University
To limit the spread of disease and reduce environmental pollution, human waste (excreta) needs to be safely contained and effectively treated. Yet 4.2 billion people, more than half of the world’s population, lack access to safe sanitation.
In developing countries, each person produces, on average, six litres of toilet wastewater each day. Based on the number of people who don’t have access to safe sanitation, that equates to nearly 14 billion litres of untreated faecally contaminated wastewater created each day. That’s the same as 5,600 Olympic-sized swimming pools.
This untreated wastewater directly contributes to increased diarrhoeal diseases, such as cholera, typhoid fever and rotavirus. Diseases such as these are responsible for 297,000 deaths per year of children under five years old, or 800 children every day.
The highest rates of diarrhoea-attributable child deaths are experienced by the poorest communities in countries including Afghanistan, India, and the Democratic Republic of Congo.
Given the global scale of this problem, it’s surprising sanitation practitioners still don’t know where exactly all the human excreta flows or leaches to, due to absent or unreliable data.
Inadequate sanitation is not only a human health issue, it’s also bad for the environment. An estimated 80% of wastewater from developed and developing countries flows untreated into environments around the world.
If an excess of nutrients (such as nitrogen and phosphorous) are released into the environment from untreated wastewater, it can foul natural ecosystems and disrupt aquatic life.
This is especially the case for coral reefs. Many of the worlds most diverse coral reefs are located in tropical developing countries.
And overwhelmingly, developing countries have very limited human excreta management, leading to large quantities of raw wastewater being released directly onto coral reefs. In countries with high populations such as Indonesia and the Philippines, this is particularly evident.
The damage raw wastewater inflicts on corals is severe. Raw wastewater carries solids, endocrine disrupters (chemicals that interfere with hormones), inorganic nutrients, heavy metals and pathogens directly to corals. This stunts coral growth, causes more coral diseases and reduces their reproduction rates.
The challenges of climate change will exacerbate our sanitation crisis, as increased rain and flooding will inundate sanitation systems and cause them to overflow. Pacific Island nations are particularly vulnerable, because of the compounding impacts of rising sea levels and more frequent, extreme tropical cyclones.
Meanwhile, increased drought and severe water scarcity in other parts of the world will render some sanitation systems, such as sewer systems, inoperable. One example is the mismanagement of government-operated water supplies in Harare, Zimbabwe leading to the failure of the sewerage system and placing millions at risk of waterborne diseases.
Even in more developed countries like Australia, increased frequency of extreme weather events and disasters, including bushfires, will damage some sanitation infrastructure beyond repair.
Improving clean water and sanitation have clear global targets. Goal 6 of the United Nation’s sustainable development goals is to, by 2030, achieve adequate and equitable sanitation for all and to halve the proportion of untreated wastewater.
Achieving this target will be difficult, given there is an absence of reliable data on the exact numbers of sanitation systems that are safely managed or not, particularly in developing countries.
Individual studies in countries such as Tanzania provide small amounts of information on whether some sanitation systems are safely managed. But these studies are not yet at the size needed to extrapolate to national scales.
A big reason behind the missing data is the large range of sanitation systems and their complex classifications.
For example, in developing countries, most people are serviced by on-site sanitation such as septic tanks (a concrete tank) or pit latrines (hole dug into the ground). But a lack of adherence to construction standards in nearly all developing countries, means most septic tanks are not built to standard and do not safely contain or treat faecal sludge.
A common example seen with septic tank construction is there are a lot of incentives to build “non-standard” septic tanks that are much cheaper. From my current research in rural Fiji, I’ve seen reduced tank sizes and the use of alternative materials (old plastic water tanks) to save space and money in material costs.
These don’t allow for adequate containment or treatment. Instead, excreta can leach freely into the surrounding environment.
A standard septic tank is designed to be desludged periodically, where the settled solids at the bottom of the tanks are removed by large vacuum trucks and disposed of safely. So, having a non-standard septic tank is further incentivised as the lack of sealed chambers reduces the accumulation of sludge, delaying costly emptying fees.
Another key challenge with data collection is how to determine if the sanitation infrastructure if functioning correctly. Even if the original design was built to a quality standard, in many circumstances there are significant deficiencies in operational and maintenance activities that lead to the system not working properly.
What’s more, terminology is a constant point of confusion. Households — when surveyed for UN’s Sustainable Development Goal data collection on sanitation — will say they do have a septic tank. But in reality, they’re unaware they have a non-standard septic tank functioning as a leach-pit, and not safely treating or containing their excreta.
Achieving the Sustainable Development Goal 6 requires nationally representative data sets. The following important questions must be answered, at national scales in developing countries:
for every toilet, where does the excreta go? Is it safely contained, treated on site, or transported for treatment?
if the excreta is not contained or treated properly after it leaves the toilet, then how far does it travel through the ground or waterways?
when excreta is removed from the pit or septic tank of a full on-site latrine, where is it taken? Is it dumped in the environment or safely treated?
are sewer systems intact and connected to functioning wastewater treatment plants that releases effluent (treated waste) of a safe quality?
Presently, the sanitation data collection tools the UN uses for its Sustainable Development Goals don’t answer in full these critical questions. More robust surveys and sampling programs need to be designed, along with resource allocation for government sanitation departments for a more thorough data collection strategy.
And importantly, we need a co-ordinated investment in sustainable sanitation solutions from all stakeholders, especially governments, international organisations and the private sector. This is essential to both protect the health of our own species and all other living things.
How do we save whales and other marine animals from plastic in the ocean? Our new review shows reducing plastic pollution can prevent the deaths of beloved marine species. Over 700 marine species, including half of the world’s cetaceans (such as whales and dolphins), all of its sea turtles and a third of its seabirds, are known to ingest plastic.
When animals eat plastic, it can block their digestive system, causing a long, slow death from starvation. Sharp pieces of plastic can also pierce the gut wall, causing infection and sometimes death. As little as one piece of ingested plastic can kill an animal.
About eight million tonnes of plastic enters the ocean each year, so solving the problem may seem overwhelming. How do we reduce harm to whales and other marine animals from that much plastic?
Like a hospital overwhelmed with patients, we triage. By identifying the items that are deadly to the most vulnerable species, we can apply solutions that target these most deadly items.
In 2016, experts identified four main items they considered to be most deadly to wildlife: fishing debris, plastic bags, balloons and plastic utensils.
We tested these expert predictions by assessing data from 76 published research papers incorporating 1,328 marine animals (132 cetaceans, 20 seals and sea lions, 515 sea turtles and 658 seabirds) from 80 species.
We examined which items caused the greatest number of deaths in each group, and also the “lethality” of each item (how many deaths per interaction). We found the experts got it right for three of four items.
Flexible plastics, such as plastic sheets, bags and packaging, can cause gut blockage and were responsible for the greatest number of deaths over all animal groups. These film plastics caused the most deaths in cetaceans and sea turtles. Fishing debris, such as nets, lines and tackle, caused fatalities in larger animals, particularly seals and sea lions.
Turtles and whales that eat debris can have difficulty swimming, which may increase the risk of being struck by ships or boats. In contrast, seals and sea lions don’t eat much plastic, but can die from eating fishing debris.
Balloons, ropes and rubber, meanwhile, were deadly for smaller fauna. And hard plastics caused the most deaths among seabirds. Rubber, fishing debris, metal and latex (including balloons) were the most lethal for birds, with the highest chance of causing death per recorded ingestion.
The most cost-efficient way to reduce marine megafauna deaths from plastic ingestion is to target the most lethal items and prioritise their reduction in the environment.
Targeting big plastic items is also smart, as they can break down into smaller pieces. Small debris fragments such as microplastics and fibres are a lower management priority, as they cause significantly fewer deaths to megafauna and are more difficult to manage.
Flexible film-like plastics, including plastic bags and packaging, rank among the ten most common items in marine debris surveys globally. Plastic bag bans and fees for bags have already been shown to reduce bags littered into the environment. Improving local disposal and engineering solutions to enable recycling and improve the life span of plastics may also help reduce littering.
Lost fishing gear is particularly lethal. Fisheries have high gear loss rates: 5.7% of all nets and 29% of all lines are lost annually in commercial fisheries. The introduction of minimum standards of loss-resistant or higher quality gear can reduce loss.
Other steps can help, too, including
incentivising gear repairs and port disposal of damaged nets
penalising or prohibiting high-risk fishing activities where snags or gear loss are likely
and enforcing penalties associated with dumping.
Outreach and education to recreational fishers to highlight the harmful effects of fishing gear could also have benefit.
Balloons, latex and rubber are rare in the marine environment, but are disproportionately lethal, particularly to sea turtles and seabirds. Preventing intentional balloon releases and accidental release during events and celebrations would require legislation and a shift in public will.
The combination of policy change with behaviour change campaigns are known to be the most effective at reducing coastal litter across Australia.
Reducing film-like plastics, fishing debris and latex/balloons entering the environment would likely have the best outcome in directly reducing mortality of marine megafauna.
Lauren Roman, Postdoctoral Researcher, Oceans and Atmosphere, CSIRO; Britta Denise Hardesty, Principal Research Scientist, Oceans and Atmosphere Flagship, CSIRO; Chris Wilcox, Senior Principal Research Scientist, CSIRO, and Qamar Schuyler, Research Scientist, Oceans and Atmospheres, CSIRO