Bioplastics: Benefits and Pitfalls

holding a plastic bag of compost

There are a lot of claims made about bioplastic products. Some are true, some are partly true, many are misleading, and most are unsubstantiated. It’s a bit of a Wild West scenario in the world of bioplastics: producers are trailblazing into new terrain in search of petrochemical plastic alternatives; everything from corn to mushrooms to poop is seen as a polymer source. Manufacturers and retailers are hot to tout what they see as “environmentally safe” plastic. Meanwhile, policymakers and regulators are scrambling to attach real definitions to the producers’ eco-fantastic labels.

There’s plenty to get excited about in terms of finding a good alternative to petrochemical-produced plastics, but we shouldn’t ride off into the sunset with bioplastics just yet.

What are bioplastics?


Bioplastics are, in simple terms, plastics made from renewable feedstocks, which can include corn, sugar cane, potatoes, coconuts, mushrooms, wheat, wood, or soy beans to name a few. (Conventional plastics are made from crude oil.) Like conventional petrochemical-produced plastics, there are several types of bioplastics: Some of the most common include poly lactic acid (PLA) derived from corn, wheat, or sugar cane, and labeled with a #7 resin recycling code; bio-polyethylene made from sugar cane or corn, with a #4 recycling code; polyhydroxyalkanoate (PHA) primarily derived from corn, with a #7 recycling code.

Bioplastics are used to make a lot of so-called “green” products like food containers, cutlery, bags, bottles, foams, electronics casings, medical supplies, and beyond. Many are compostable, a few might be biodegradable, and some are also recyclable.

Sounds great, doesn’t it—a naturally derived plastic from a renewable source that just melts back into the Earth when we’re done with it? We hate to break your bioplastic bubble, but not all of these biomass-produced polymers are environmentally innocent.  

Renewable Isn’t Always Green

You probably noticed that many of the renewable feedstocks used to make bioplastics are agricultural crops—corn, sugar cane, soy beans. Industry cowboys are quick to point that out, too. But what they aren’t so forthcoming about is that much of the corn used for bioplastics is a GM (genetically modified) crop, and that crop requires a lot of industrial fertilizers, pesticides, water, and land to produce. For example, NatureWorks, one of the largest manufacturers of PLA bioplastic in the US (a subsidiary of Cargill, one of the largest suppliers of genetically modified corn in the world), uses—you guessed it—GM corn.

Magnify this process to a global scale: GM crops expanding, huge swaths of land being converted to agriculture but not for food, more deforestation, more fertilizers and pesticides being used, food costs continuing to soar, and food shortages becoming even more of an issue. Suddenly, the scenario isn’t so Earth-friendly. Sure, the stuff isn’t made from crude oil, which decreases use of fossil fuel and the production of greenhouse gases, but it has negative consequences in other ways.

But not all bioplastics use genetically modified corn, or even corn, and innovations using more sustainable biomass, like algae and even chicken feathers, are already underway. There are promising results by a California-based start-up converting sewage into biodegradable bioplastic. There’s certainly no shortage of human waste! According to Heeral Bhalala, a research associate in sustainable plastics for the Institute for Local Self-Reliance (ILSR), even mega-companies like PepsiCo. are greening bioplastics: “[They] are already working on using the food scraps from their food production plant to create 100% biobased bottles for their beverages.”

That said, even if bioplastic companies start using abundant, low-impact materials for their products, we can’t neglect to consider the end-of-life cycle of many of the bioplastics—that is to say, their ability to biodegrade, compost, or recycle.

Beware of Biodegradability Claims

This is the category in which bioplastics theoretically have huge benefits. Bioplastic producers like to hoot and holler about their bioplastics being 100% biodegradable and/or compostable. Not every bioplastic is biodegradable (e.g., bio-polyethylene (#4) is only recyclable), and even those that do biodegrade may only do so in specific environments, if at all. ILSR’s Heeral Bhalala states that most product claims of biodegradability “are usually not true.”

Part of the problem is that there are loose standards for what qualifies as biodegradable, and there’s virtually no third-party verification of manufacturers’ biodegradability claims. The Federal Trade Commission “Green Guide” gives a broad definition for biodegradability for manufacturers to use a guide in terms of marketing, but the FTC is an agency built to protect consumers from deceptive advertising—it doesn’t make environmental policy or set the standards.

ASTM International, an organization that develops international standards across various industries, created pass/fail standards for biodegrading and composting that are generally accepted and trusted. Yet, know that these are voluntary standards; bioplastic products aren’t required to be tested, except in California.

In terms of specific legislation, California passed laws that require products with compostable or biodegradable labels pass ASTM standards. And the USDA’s Certified Biobased Product label, which verifies that a product contains a proven amount of renewable biological ingredients using ASTM standards, just went into effect in February of 2011. Further legislation for marketing claims and stricter definitions of terminology are sure to come either on a federal or state level, or both.

However, even biodegrading bioplastics that pass ASTM standards need to be looked at carefully. You have to ask what conditions are required for that biodegradation? By and large, the answer is an aerobic or oxygen-filled environment (a field, a forest, an ocean) with adequate microbes to start munching away at the stuff. Here’s the hitch: a lot of plastics (petrochemically produced or biomass produced) end up in landfills. The Environmental Protection Agency reports on its Web site that “only 7 percent of the total plastic waste generated in 2009 was recovered for recycling.”

Let’s be clear on this: landfills are designed to be as anaerobic (oxygen-void) as possible—the things are practically hermetically sealed to prevent as much decay as possible. Melissa Hockstad, Society of the Plastics Industry’s Vice President of Science, Technology and Regulatory Affairs and Director of the SPI Bioplastics Council, put it bluntly, “Bioplastics are not currently designed to degrade in a landfill.”

In short, even bioplastics from the most sustainable feedstocks aren’t going to benefit the environment any more than conventional plastics if they end up in landfills. They must be disposed of in a way that allows them to biodegrade or compost.

Coordinating Composting

A biodegrading product is not held to the same standards as a composting product; composting is a more strictly defined, standardized process of degrading. “Biodegradable” means a product will break down and return to the Earth in a “reasonably short time,” according to the FTC Green Guides. They may need the help of a municipal composter to do so.

Composting bioplastics shows a lot more promise than biodegrading. “Compostable,” according to the FTC, means the product will degrade into “useable, compost-humus-like material that enriches the soil and returns nutrients to the Earth.” According to the FTC, they are supposed to degrade just like leaves and food waste in a backyard composter, but due to a lack of oversight with this label, the fact is that many will still need a municipal composter to fully break down.

Right now, consumers probably should assume that current “biodegradable” and “compostable” bioplastics can only be composted in a commercial composting facility with controlled heat and moisture (i.e., generally not the backyard heap). Sadly, these composters are few and far between, the majority do not accept material from individuals, and some may ban bioplastics anyway, since many bioplastics are indiscernible from conventional plastics. A lot of progress still needs to be made simply in terms of public access.

On the bright side, detailed international standards for compostability already exist, and the noprofit Biodegradable Products Institute (BPI) created a Compostable Label program that verifies company’s composting claims. Additionally, the Sustainable Biomaterials Collaborative (SBC) created a set of guidelines and recognition levels for compostable biomass-based food serviceware called the BioSpecs, which take into account issues of environmental protection, health, social and economic justice, and material resources. Hopefully paving the way for more cities, San Francisco and Seattle implemented   city-wide compost curbside pick-up programs that accommodate compostable bioplastics; Seattle’s municipal composter, Cedar Grove, even has its own approval label on compostable products that reads “Cedar Grove Approved.”

For other ways to get your compostable bioplastics to a commercial composter, Heeral Bhalala of ILSR suggests seeking out the compostable bins at Whole Foods (not all stores have them) and other sustainably minded stores and restaurants, which often have compost-hauling services. And you can look up your nearest municipal composter and see if it’s one of the few that accept waste from individuals on the Web site

For home-composters willing to try it, Bhalala says “it’s good to test composting [bioplastic] products in your own backyard compost pile. They do require higher temperatures to compost and are slower to break down, so it helps to shred them to increase their surface area and to put them in the middle of the compost pile.”

Melissa Hockstad, of SPI, states that the US Composting Council is “… working on growing the composting industry in the US such that more people have more access to [commercial composting] facilities, which is beneficial for bioplastics such as PLA and PHA.” But until composting facilities are readily available and accessible, bioplastics could most often end up hauled off to landfills.

Recycling Bioplastics

Recycling bioplastics isn’t always an easy accomplishment. Recyclers fear that non-petroleum-based plastics will corrupt their streams (many bioplastics have lower heat resistance—and that whole biodegrading thing they might do is not desirable in the eyes of recycled plastics manufacturers for fear that the recycled plastic will degrade prematurely).

Most bioplastic manufacturers say recyclers’ concerns are unfounded.  In fact, bioplastics are recyclable; bio-polyethylene (given a #4 resin recycling code) is even accepted in many traditional recycling streams. As for bioplastics PLA and PHA (the #7s), they are generally not accepted by municipal recycling collections, but some manufacturers offer to take back their products for recycling. However, there is no infrastructure for individuals to collect and transport the plastics back to the manufacturers, so for those unwilling to mail their bioplastics back to the manufacturer, in the trash it goes!

In essence, current US recycling and composting facilities just haven’t caught up with bioplastics. And in order to give recyclers and composters the incentive to start to invest in accepting bioplastics in their streams or facilities, there needs to be a significantly larger volume of bioplastics to recycle or compost. Basically, the problem has to get worse before it will get better. The current and predicted growth rate for the bioplastics industry (estimated to be upwards of 40% in the next four years by some experts, like Melissa Hockstad), might make that happen sooner than later.

The Toxicity Question

As we reported in the Nov/Dec 2011 Green American, plastics are rarely just made out of oil—they’re mixed with a host of chemical additives to enhance their capabilities, i.e. make them more flexible or less flammable, to prevent them from degrading or to tint them pretty colors, write Mike Neal and Dr. Anthony Andrady in a 2009 research paper published in the Royal Society’s Philosophical Transitions B. The same holds true for bioplastics—they aren’t just made from plants. They may have the same toxicity issues that a conventional plastic does.

In October 2010, a team from the University of Pittsburgh released an analysis of both petro- and corn-based PLA bio-plastics for toxicity and environmental life-cycle impact (from cradle to end use, not including disposal), published in Environmental Science and Technology.  The bioplastics were more toxic than conventional plastics when it came to releasing ozone-depleting chemicals, carcinogens, acidification, eutrophication (contributing to dead zones in bodies of water, usually via fertilizer runoff) and eco-toxicity.

These impacts came largely from fertilizer and pesticide use associated with growing the corn feedstock for the bioplastics, say the researchers. And critics of the study note that it did not take bioplastics’ sustainability trump card—its ability to biodegrade or compost—into account at all in the lifecycle analyses, which may have put bioplastics far ahead of petro-plastics in more categories.

But analyzing the manufacturing of bio-based feedstock into plastics did contribute to the researchers’ toxicity rankings.

In addition to feedstocks, chemical additives and manufacturing processes will differ between manufacturers. Other, more responsible manufacturers not included in the University of Pittsburgh’s analysis have demonstrated far different results when it came to the toxicity of their products.

What consumers can learn from this study is that just because a plastic is plant-based doesn’t make it 100 percent nontoxic.

An Evolving Industry

Responsibly manufactured bioplastics make a lot of sense in many ways. At the most basic level, they aren’t derived from petroleum, and reducing dependence on oil is always a good thing. There’s no question that conventional plastics are an enormous problem for the environment on many levels, from their production to their disposal. Adding urgency to the matter are the expected continued growth of the use of plastics and dismal rate of plastics recycling. Secondly, based on the information we know now about bioplastics, they don’t stick around for hundreds of years, though they probably don’t degrade as quickly as most manufacturers claim—certainly not if they are in a landfill.

At this point, corn, sugar cane, or soy beans may not in sum be significantly better than petrochemicals as a source for plastics, but it’s a start. Bioplastics are still a new industry and it’s evolving almost daily. Nonprofit, watchdog groups (like BPI and SBC) are stepping in where state and federal laws and regulations lag, too. Companies that are using corn, even GM corn today, are already looking to other biomass to produce their bioplastics in the future.

Given enough pressure from consumers, environmental groups, and federal agencies on bioplastics manufacturers, recyclers, and composters to coordinate their efforts, improve accessibility, and become greener, we could end up with a truly biodegradable, compostable, recyclable bioplastic—and live happily ever after.

What to Look for in Bioplastics

In the meantime, the path of least impact is to use compostable bioplastics, especially if you’re able to compost them through a commercial composter or through trial and error in your own compost pile (remember it could take a long time to fully degrade). Heeral Bhalala of ILSR recommends seeking out bioplastics that meet as many of the following criteria as possible:

- Made from biomass, not a conventional plastic with biodegrading additives (e.g. BioGreen Bottles)

- Meets at least a SBC BioSpec Bronze level

- Meets ASTM (D6400 or D6868) or EN 13432 standards of compostability or displays BPI’s Compostable Label or Cedar Grove Approved logo (European companies Vinçotte and Din Certco also have compost labels)

- Made from as much biomass material as possible, preferably displays the USDA Certified Biobased Product label

- Made from GMO-free crops


From Green American Magazine Issue