Bioplastics' Contribution to Plastic Pollution

Bioplastics aren’t necessarily greener. Producing them may require more energy, cause more pollution, and detract from lands available for food production in a world with a lot of hungry people.

Bioplastics and plastic pollution

Plastic pollution is still an issue with bioplastics.

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In Plastic Purge (St. Martin's Press, 2014), ecologist Michael SanClements has put together the most up-to-date and scientifically backed information available to explain how plastics release toxins into your body and the effect they have on your health (and that of your children). In this excerpt, the negative effects of bioplastics and how they contribute to plastic pollution are discussed.

You can purchase this book from the MOTHER EARTH NEWS store: Plastic Purge.


Bioplastics (and biofuels) are becoming increasingly popular and easier to find in everyday life. In both cases, it’s a seemingly wonderful and simple solution to a big problem, but when you dig deeper, in reality it’s actually very complicated and not necessarily the panacea we may have hoped.

Currently, bioplastics represent a very small (less than 1 percent) but rapidly growing part of the plastics market. Some estimates project growth as high as 30 percent per year (30 percent increase in the amount of bioplastics, not 30 percent of the entire plastics market).

Some big names in bioplastic manufacturing within the United States are NatureWorks—a collaboration between the Japanese company Teijin and the US company Cargill—and Metabolix, based in Cambridge, Massachusetts. While still a very small part of the overall plastics market, bioplastics have benefited from both extremely high oil prices and the recent trend toward environmentalism and preference for “greener” products in consumer choices. The bioplastics market in the United States is estimated to reach a value of $680 million by 2016 and is expected to continue growing in the future. In 2012 both North America and Europe were using approximately 27 percent of their estimated available bioplastic production capacity, meaning companies in both countries have the ability to significantly step up production should they want to. Whether the bioplastics industry grows to fill those capacities remains to be seen.

Since bioplastics still comprise only an extremely small part of the plastics market (less than 1 percent, remember?), I think the most important question to ask is: do we really want that value to grow? And if it does, can it do so in a manner that makes sense from an environmental perspective? I know it may seem like bioplastics are ideal for sustainability, but the reality of the situation is that they aren’t a cure-all for our plastic problem.

Have you ever heard the term “greenwashing”? Greenwashing is a form of spin in which marketing is deceptively used to make a company, policy, or product look environmentally friendly, when in reality it’s anything but. Whether it is to increase profits or gain political backing, greenwashing’s goal is to manipulate popular opinion to garner support for things or sell products that really aren’t so green at all. I employ the term “greenwashing” here because both biofuels and bioplastics rely on it to a degree. Their marketing campaigns tend to boil a very complex issue down to a somewhat deceptive brand logo, like an image of a happy green cornstalk under puffy white clouds. I urge you to think back to the discussion of life cycle assessments and remember to always consider the whole picture (or life cycle) when presented with seemingly green ideas, products, or politics. With bioplastics, it’s easy to leave out a large portion of the life cycle and come to some very erroneous conclusions regarding the costs. Often omitted is the amount of energy that goes into, and the negative effects related to, the growing, harvesting, and transportation of bioplastics. Also, in a world full of hungry people, do we really want to be pushing agricultural lands into production of plastics rather than food?

I’m not saying that bioplastics are all bad—they aren’t. But realizing their shortcomings is critical to making informed decisions as consumers and citizens. To add another layer of complexity, just as with regular plastics, there are several types of bioplastics, each with their own characteristics to consider.

When I hear the term “bioplastics,” I think it’s some snazzy new invention, but these have actually been around for a really long time. Henry Ford even used corn-based plastics in the construction of the Model T in the early 1900s. In modern society there are two popular types of bioplastic: polylactic acid (PLA) and polyhydroxyalkanoate (PHA). Both PLA and PHA cost more than traditional plastics to produce. This is one of the greatest barriers to bioplastics expansion. For now, PLA costs about 20 percent more and PHA is nearly double the price of traditional petroleum-based plastics, but this could change. PLA and PHA are made using starches and sugars (e.g., cornstarch) and both degrade easily, or at least there are claims that both degrade easily. However, PHA can handle higher temperatures than PLA, making it more durable in a sense. Yet Metabolix, the primary manufacturer of PHA, claims that PHA is so biodegradable it will break down in streams and seawater without even being composted!

The issues surrounding the sustainability of bioplastics are, not surprisingly, quite complex. A particularly fascinating concern regarding bioplastics is of a behavioral nature. Steve Davies, the marketing director for NatureWorks, raises an interesting point about consumer behavior with regard to items like bioplastic bottles when he says, “They’ll think, ‘Oh, I can flip it out the car window and it will disappear on the side of the road,’ and it absolutely won’t.” Even in the instances where people do pay attention and place bioplastic items in the recycling bin, they usually wind up in the landfill anyway. Bioplastics get rejected from the recycling stream because the majority of recycling centers in the United States are still unprepared to handle them. Which means one of two things: either the bioplastic item ends up in a batch of regular recycling, where it becomes a contaminant, or it gets tossed into a landfill.

When bioplastics get tossed into a landfill they decompose in an anaerobic environment to form methane (CH4), a green house gas twenty-one times more effective at trapping heat than carbon dioxide. So you can see how that might not be a great thing. However, landfills can be equipped with the ability to capture methane and create energy to power all sorts of things. Many landfills in the United States are already equipped with this very technology. We actually excel in this department: “nearly 60 percent of the worldwide capture of methane occurs in the United States even though the US only generates 24 percent of the worldwide methane,” according to a report on The Importance of Landfill Gas Capture and Usage in the U.S. by the Council for Sustainable Use of Resources at the Columbia Earth Engineering Center. The potential for this technology to mitigate green house gas emissions and to generate power is quite astounding. The Intergovernmental Panel on Climate Change estimates “gas collection and utilization could reduce methane emissions from landfills globally by 70 percent at negative to low costs by 2030.” The report by Columbia concludes using methane generated by landfills is a “win/win opportunity,” the reason being that using the methane created in landfills to create energy converts that methane back to carbon dioxide, which is the very same gas that would have been created if the waste didn’t end up in the landfill in the first place. And you can still obtain the primary energy benefit of the methane at the same time.

All this talk of landfills isn’t to say that bioplastics are inherently unrecyclable, because they aren’t. PLA is actually highly recyclable and can be recycled over and over again. But it cannot be mixed with the traditional plastic recycling stream. Therefore, a good method for separating bioplastics from petroleum-based plastics is needed. Germany, Switzerland, and Sweden require manufacturers to prominently mark products that are compostable so they can be identified and separated. The best separation method is infrared scanning, which can be used to differentiate between plastic types; unfortunately, this is an expensive technology that is out of reach for many of the small recycling facilities in the United States. Others have suggested a uniform color designation for compostable plastic products would help people to sort them.

Bioplastics don’t necessarily free us from the concerns of endocrine disruptors either. For example, Europe an Bioplastics states “its members are committed to avoiding the use of harmful substances in their products. Many plastic products do not use any plasticisers and a range of acceptable plasticisers is available if necessary. The wide range of bioplastics is based on thousands of different formulas. This means specific information regarding a certain material or product can only be obtained from the individual manufacturer, converter or brand owner using the material.” So there is no uniform answer. They may have endocrine disruptors, they may not. Best to just avoid plastic all together.

Understanding the other potential downfalls associated with bioplastics should also inform your decisions.

A paper in Environmental Science & Technology, a well-regarded peer-reviewed journal, conducted life cycle analyses of several bioplastics versus traditional non-bioplastics and found some rather interesting results. The study rated the different plastics on a number of categories ranging from human health concerns, like potential to cause cancer, to environmental health effects, like global warming and eutrophication (the overloading of nutrients to waterways). This study used a “cradle to gate” assessment, meaning that it included the production of the plastics but not their use or disposal. In the case of assessing bioplastics, disposal may obviously have some benefits relative to traditional plastics. That is to say, what’s the benefit of a plastic that composts rather than persists? Leaving out disposal seems kind of stupid, I know, but there is a good reason for this, which is that there is little quantitative information on the emissions and energy from degradation of bioplastics on which to base an LCA.

The assessment’s results are a little bit surprising in that the bioplastics came out looking far less green than you might expect. The LCA conducted by Environmental Science & Technology found that bioplastics ranked most poorly in five of the ten categories assessed in this study, including ozone depletion, acidification, eutrophication, carcinogens, and ecotoxicity. That means that bioplastics, when assessed on a “cradle to gate” scale, may not always be so great, especially relative to more simple traditional plastics. The production of HDPE, LDPE, and PP did not result in the maximum impact in any category, likely because these are simple polymers that require less chemical processing than others. The authors make the point that “adhering to green design principles reduces environmental impact in either the petroleum or biological polymer categories. Switching from petroleum feedstocks to biofeedstocks does not necessarily reduce environmental impacts.” The article also steps back and makes the recommendation that limiting bioplastics to those made from renewable resources that require little pesticide use or fertilizer might be an excellent thing for further mitigating the negative impacts bioplastic production. Harvesting invasive plants for such purposes comes to mind. I like the idea of cleaning up problems and producing plastics at the same time.

Bioplastics: The Solution to All Our Plastic Problems?

1. Right now bioplastics account for less than 1 percent of plastics.

2. Bioplastics aren’t necessarily greener. Producing them may require more energy, cause more pollution, and detract from lands available for food production in a world with a lot of hungry people.

3. Advances and innovation in the production of bioplastics does make them promising. PHA plastics are produced by microbes and there are companies that claim to be producing carbon negative plastics without utilizing valuable cropland.

Reprinted with permission from Plastic Purge by Michael SanClements and published by St. Martin's Press, 2014. Buy this book from our store: Plastic Purge.