Australia is responsible for over 13 thousand tonnes of plastic litter per year. At the end of June 2018, the Australian government released an inquiry report on the waste and recycling industry in Australia. One of the recommendations was that we should phase out petroleum-based single-use plastics by 2023.
This means a real social shift, because the convenient plastic products that we use once and throw away are ubiquitous in Australia.
Bans, as Coles and Woolworths recently adopted for plastic bags, are one option – but are not suitable for every situation. They can also feel like an imposition, which can inspire backlash if the community is not on board. Behavioural science can offer a path to curb our plastic use.
Technology alone is not the solution
First off, plastic is not evil: it’s flexible, durable, waterproof and cheap. The issue is the way we dispose of it. Because plastic is so versatile it has been adopted across a range of single-use “throw away” consumer products.
Many people are working on technological solutions to our plastic problems. These range from better recycling techniques and biodegradable “plastics” made from algae or starch, to (my favourite) using the wax moth caterpillar or “mutant bacteria” to consume plastic waste.
But these options are slow and expensive. They can also have other environmental impacts such as greenhouse gas emissions and resource consumption.
There are lots of reusable alternatives to many single-use products. The challenge is getting people to use them.
Behavioural science to the rescue
My research involves applying insights from various disciplines (like economics, psychology, sociology or communication) to understand how governments and businesses can encourage people to change their behaviour for environmental, social and economic benefits.
Research has found that simply providing information through awareness campaigns is unlikely to change behaviour. What media attention and campaigning can do is increase the public visibility of an issue. This can indirectly influence our behaviour by making us more open to other interventions and by signalling social norms – the unwritten rules of acceptable behaviour.
Successful behaviour change campaigns must empower individuals. We should be left feeling capable of changing, that changing our behaviour will impact the problem, and that we are not alone. One positive example is modelling sustainable behaviours, like using KeepCups or beeswax wraps, in popular TV shows.
Once we’re aware of an issue, we may need a little help to move from intention to action. One strategy for providing this push is a small financial disincentive, like Ireland’s famous “plastax” on single-use plastic bags. Many cafés also offer discount coffees to reward bringing reusable cups.
We can also encourage retailers to “change the default”. Japan increased the refusal rate of plastic bags to 40% after six months of cashiers simply asking people if they wanted a bag.
This approach could be used for other products too. For example, imagine your drink not coming with a straw unless you specifically ask for it. This would cut down on waste, while also avoiding the unintended consequences of banning a product that is important for people with a disability.
Given that there is already strong support for reducing our reliance on single-use plastics, another simple solution would be to provide prompts in key locations, like carparks and workplaces, to remind people to bring their reusables.
While we may have the best of intentions to carry reusables, our old habits can often get in the way. Defaults and prompts can help to bring our good intentions in line with our actual behaviours.
Consumer demand also encourages manufacturers to make more convenient reusable options, like collapsible coffee cups and metal keychain straws. Businesses can also make reusables more accessible by introducing product-sharing schemes like the Freiburg Cup in Germany or Boomerang Bags in Australia.
No ‘one size fits all’ solution
Different situations need different solutions. Product sharing or reusable coffee cups might work in an office or café where the same customers return regularly, but would be impractical at a gallery or museum where customers vary each day.
For societal-level change multiple approaches are more effective than any one initiative alone. For example, if we wanted to phase out plastic cutlery nationally, we could start with an awareness campaign that encourages people to carry reusable alternatives. Then, once the community is on board, implement a small fee with some reminder prompts, and finally move to a ban once the majority have already changed their behaviour.
The key to successfully phasing out our reliance on single-use plastic products is to change the norm. The more we talk about the problem and the solutions, the more businesses will seek out and offer alternatives, and the more likely we are to mobilise together.
Microplastics in the ocean, pieces of plastic less than 5mm in size, have shot to infamy in the last few years. Governments and businesses targeted microbeads in cosmetics, some were banned, and the world felt a little better.
Dealing with microbeads in cosmetics is a positive first step, but the reality is that they are just a drop in the ocean (less than a billionth of the world’s ocean).
Microplastics in soil may be a far greater problem. Norwegian research estimates that in Europe and North America, between 110,000 and 730,000 tonnes of microplastic are transferred to agricultural soils each year.
Here lies the issue: we know almost nothing about microplastics in global soils, and even less in Australian soils. In this article we take a look at what we do know, and some questions we need to answer.
How microplastics get into agricultural soil
Sewage sludge and plastic mulch are the two biggest known contributors of microplastics to agricultural soil. Australia produces about 320,000 dry tonnes of biosolids each year, 55% of which is applied to agricultural land. Biosolids, while controversial, are an excellent source of nutrients for farmland. Of the essential plant nutrients, we can only manufacture nitrogen. The rest we must either mine or recycle.
Sewage treatment plants receive water from households, industry, and stormwater, each adding to the load of plastics. Technical clothing such as sportswear and quick-dry fabrics often contain polyesters and polyamides that break off when clothes are washed. Tyre debris and plastic films wash in with the stormwater. Treatment plants filter microplastics out of the water, retaining them in the sludge that is then trucked away and spread over agricultural land.
In agriculture, plastic mulch suppresses weeds, keeps the soil warm and damp to assist germination, and improves yield. Over time, these mulches break down, and some fragment into smaller pieces.
Biodegradable bioplastic mulches are designed to break down into carbon dioxide, water, and various “natural substances”. Environmentally friendly plastics are often more expensive, raising the question of whether businesses will be able to afford them.
Other potential sources of plastics in agricultural soil include polymer sealants on fertilisers and pesticides, and industrial compost. Unsold food is often sent to the composting facility still in plastic packaging, and with plastic stickers on every apple and kiwi fruit.
The Australian Standard for composts tacitly recognises that microplastics are likely to be present in these products by having acceptable levels of “visible contamination”. Anyone who has bought compost or garden loam from a landscaping supplier may have noticed pieces of plastic in the mix.
In horticulture, particularly as green walls and green roofs grace more buildings, polystyrenes are used deliberately to make lightweight ‘soil’.
There might be other pathways we don’t know about yet.
What happens once microplastics are in the soil?
Here we stand at the edge of the cavernous knowledge gap, because we don’t know the effect of microplastics in our soil. The overarching question, physically and biologically, is where do microplastics go?
How plastics fragment and degrade in the soil depends on the type of plastic and soil conditions. Compostable, PET, and various degradable plastics will behave differently, having different effects on soil physics and biology.
Fragments could move through soil cracks and pores. Larger soil fauna might disperse fragments vertically and laterally, while agricultural practices such as tillage could push plastics deeper into the soil. Some fragmented plastics can absorb agrochemicals.
Soil microbes can break down some plastics, but what are the byproducts and what are their effects? Newer, biodegradable bioplastics theoretically have limited impact as they break down into inert substances. But how long do they take to break down in different soil and climatic conditions, and what proportion in the soil are non-degradable PET plastics?
Both the main form of carbon in soil and polythene (the most common type of plastic) are carbon-based polymers. Could the two integrate? If they did, would this prevent plastics from moving deeper into the soil, but would it also stop them breaking down?
Could plastics be a hidden source of soil carbon storage?
Bioaccumulation is when something builds up in a food chain.
Research into microplastic accumulation on land is sparse at best. A 2017 study in Mexico found microplastics in chicken gizzards. In the study area, waste management is poor and most plastics were ingested directly from the soil surface as opposed to having bioaccumulated.
Nematodes can take up polystyrene beads suggesting some potential for bioaccumulation, however earthworms have reduced growth rate and increased mortality when they ingest microbeads.
Larger microplastics are unlikely to cross plant cell membranes, but it’s possible that plants can absorb the chemicals formed when plastic degrades. Plants have natural mechanisms to keep contaminants out of their fruiting bodies – pieces of plastic in apples or berries is highly unlikely – but root vegetables and leafy greens are a different story.
Metals can accumulate in leafy greens and the skin of root vegetables – could plastics or their byproducts do the same?
This is before we even get to nanoplastics, which are 1-100 nanometres wide. Can plant roots can absorb nanoplastics, and can they pass through an animal’s gut membrane?
Where to now?
The first step is to quantify how much plastic is currently in the soil, where it is, and how much more to expect. This is more difficult in land than water, as it’s easier to filter plastics out the ocean than to separate them from soil samples. The smaller the plastics are, the harder they’ll be to track and identify – which is why research must start now.
Research needs to address the different types of plastics, including beads and other synthetic fibres. Each is likely to act differently in the soil and terrestrial ecosystems.
Understanding how these plastics react will inform the next obvious questions: at what quantity do they become hazardous to soil, plant and animal life, and how can we mitigate this impact?
Plastics in soil represent artefacts of human civilisation. Soils are full of human artefacts; if this was not the case then there would be no field archaeology. However, the effects of microplastic may persist far longer than our own civilisation. We must fill in our knowledge gaps swiftly.
Alisa Bryce, Research Affiliate, University of Sydney; Alex McBratney, Professor of Digital Agriculture & Soil Science; Director, Sydney Institute of Agriculture, University of Sydney; Budiman Minasny, Professor in Soil-Landscape Modelling, University of Sydney; Damien Field, Associate professor, and Stephen Cattle, Associate professor, University of Sydney
Earlier this year, Melbourne and large areas of Central Victoria, experienced days of smoke haze and poor air quality warnings as a result of planned burns. It’s a regular event occurring every autumn.
But this is only part of the story. A good proportion of the smoke this autumn has actually come from the intensive burning of debris left behind after clearfell logging. This is essentially industrial pollution.
Industrial clearfell logging vs fuel reduction
To understand why clearfell logging burns are different compared with planned burns to reduce bushfire risk, we need to understand clearfell logging, which involves cutting most or all of the commercially valued trees in one single operation across a designated area (called a “coupe”).
In the process of clearfell logging, understorey vegetation is usually pushed over. Along with tree heads and branches left behind after logging, large volumes of debris – known as “slash” – are created. This is partially removed by applying a high intensity burn across the coupe, which in turn establishes an ash seed bed for the next crop of trees to be established. Generally, around 90-100% of the coupe is burnt.
In contrast, planned burns to reduce bushfire risk (otherwise referred to as fuel reduction burns) are less intense. They mostly target “fine fuels” (vegetation less than 6mm in diameter) on the forest floor and in the understorey, which may average around 15 tonnes per hectare (t/ha). Burn coverage is usually 50-70% of the site.
Clearfell logging burns consume much larger volumes of vegetation biomass in the form of tree heads, branches, bark and downed understorey vegetation. According to a report completed for the National Carbon Accounting System, clearfell logging burns consume, on average, 130 t/ha of slash in mixed-species forest and 140 t/ha of slash in Mountain Ash forests. This means that, while clearfell logging burns cover much less ground than fuel reduction burns, they burn far more biomass per hectare – generating far more smoke.
The list of planned burns on Forest Fire Management Victoria’s website showed that, at the beginning of May, 77 of the 119 burns either lit or planned to be lit across the Central Highlands of Victoria and surrounding areas were on logging coupes.
These burns were individually lit over a period of weeks, with some days predominantly logging burns, others fuel reduction burns. An example when logging burns were prominent occurred on April 20 this year, where 10 out of 12 planned burns were observed as occurring on logging coupes. Using a simple calculation based on average biomass consumption, fuel loads and burn coverage for logging and fuel reduction burns, we estimate that up to 99% of biomass burnt most likely occurred on logging coupes. The following day, the Environmental Protection Authority observed “poor” air quality at multiple air monitoring stations across Melbourne due to smoke.
Even on days when the majority of burns lit were for fuel reduction, planned logging burns still contributed a proportion of biomass burned. For example, on April 30, only three out of 12 planned burns were observed as occurring on logging coupes, but they may have contributed to around one-third of the total biomass burned.
Likewise, on the following day, the Environmental Protection Authority observed “very poor” air quality across multiple air monitoring stations. While multiple planned burns contributed to this pollution event, we contend that logging burns increased the levels of pollution in addition to the smoke originating from fuel reduction burns.
The key issue here is that not all “planned burns” are equivalent. Fuel reduction burns are intended to reduce the bushfire risk to lives and property. Indeed, work led by The Australian National University shows that regular fuel reduction burns can reduce risk to properties if carried out within close proximity.
In contrast, clearfell logging burns are part of an industrial process that extracts pulp logs and sawlogs for commercial sale to private enterprise. They play no part in reducing bushfire risk to life and property. Actually, the reverse is true: logging makes forests more prone to subsequent high-severity crown-consuming fires with associated risks to communities.
Given that a substantial proportion of the recent smoke over Melbourne and surrounding regional Victoria likely originated from logging burns, could that smoke be deemed industrial pollution? This is a valid question, given the serious health impacts associated with smoke pollution.
Logging burns would not be needed (and a substantial amount of associated smoke not generated) if the forest had not been logged in the first place. It is imperative that government departments inform the public about the smoke pollution coming from logging operations, whose purpose is for private commercial gain.
The manufacturer of White King “flushable” wipes has been fined A$700,000 because these are not, in fact, flushable. The wipes, advertised as “just like toilet paper”, cannot disintegrate in the sewerage system, and cause major blockages.
The Federal Court found Pental Products and Pental Limited, which manufacture the wipes, guilty of making false and misleading representations. In particular, Pental claimed that the wipes would break down in the sewerage system, like toilet paper does.
So-called flushable wipes, now sold for everything from make-up removal to luxury toilet paper, are a growing hazard to public health. Sydney Water says 75% of all sewer blockages in the city’s waste-water system involve wipes.
Don’t trust the label
While wipes might look a bit like toilet paper, there are major differences. Wipes are made from a very tough material called “air-laid paper”, and are often impregnated with cleansing chemicals, disinfectants and cosmetic scents.
Air-laid paper behaves very differently in sewers to toilet paper and does not readily disintegrate in water.
When in sewer pipes the resilient wipes have a tendency to entangle with other wipes and create blockages. This is a bit like the knot of tangled clothing sometimes found in the washing machine. Sewerage system managers around the globe seem powerless to prevent the problem.
Sewer blockages caused by wipes look grotesque. Unpleasant work in confined places is required to remove the blockages (some of which is done by hand!). In 2016 Newcastle’s Hunter Water removed an ugly seven-metre snake of wipes and assorted sewage debris, weighing roughly a tonne, from its sewers.
Wither do you wipe?
Wipes become very popular in the 1990s to help in cleaning babies’ bottoms while changing nappies. Since then, many similar products (“wet wipes”, “baby wipes” and “face wipes”) have proliferated well beyond the baby aisle.
Wipes may be advertised for personal hygiene, removing makeup and cleaning hands. Others are marketed for cleaning bathroom surfaces, toilets and other household areas. The marketing of wipes often boasts how easy they are to dispose by simply flushing them down the toilet.
More recently, a booming adult market is expanding their use as a luxury alternative to toilet paper, buoyed by endorsements from celebrities like Will Smith and Will.i.am. Research by Sydney Water found that males in the 15-44 bracket particularly preferred to use wipes rather than toilet paper. The same market survey estimated that a quarter of Sydney Water’s 4.6 million customers flush wipes down the toilet rather than putting them in a bin.
The three Ps
The fine imposed on Pental Products and Pental Limited for their “flushable” wipes is an important signal to others in this growing market.
However, wipes are not the only waste item that people should not flush down the toilet. This issue gained international notoriety in 2017 when Thames Water in London removed a 130-tonne monster sewer blockage, in a difficult and laborious three-week operation. The blockage was an accumulation of solids called a fatberg – a nightmarish combination of wipes, congealed fat, nappies, female sanitary products, and condoms.
Have we forgotten what toilets are for? The Australia Water Association reminds us that they are for the three Ps: pee, poo and paper (toilet paper only).
Perhaps people should visit an Irish website called think before you flush. It lists other common waste objects that should not be flushed, such as cigarette butts, cotton buds, dental floss, hair and unwanted medication. It also advises that a bin be placed in each bathroom.
Hopefully, packets of wipes will now carry warning labels to advise users not to flush them down the toilet. Just because you can flush something down the toilet does not mean it is good for the environment or society to do so.