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Even the Sustainable Packaging Coalition isn't buying biodegradability

Science appears to be taking the upper hand at the Sustainable Packaging Coalition (SPC). A paper, titled "The SPC Position Against Biodegradability Additives for Petroleum-Based Plastics," and an open forum webinar held on this topic on Dec. 16 are enlightening in this regard.

Clare Goldsberry

December 30, 2015

5 Min Read
Even the Sustainable Packaging Coalition isn't buying biodegradability

Science appears to be taking the upper hand at the Sustainable Packaging Coalition (SPC). A paper, titled "The SPC Position Against Biodegradability Additives for Petroleum-Based Plastics," and an open forum webinar held on this topic on Dec. 16 are enlightening in this regard. It seems that SPC, which "takes a material-neutral, lifecycle-oriented approach to packaging sustainability with a goal of enabling and encouraging a more sustainable economy for all materials," has found in its studies—and concluded—that the use of "biodegradability additives for conventional petroleum-based plastics . . . do not offer any sustainability advantage and may actually result in more environmental harm. These additives should not be used," says SPC.

The formal position paper against the use of biodegradability additives in plastics explains that one of the problems is that the term biodegradability "suggests that nutrients will beneficially return to the environment at the material's end of life." Yet it is actually compostability that is the "superior and preferred indicator of a material's ability to result in nutrient renewal and reuse." Compostability is defined as a "material's ability to successfully undergo a managed process that controls biological decomposition and transformation into a stabilized organic matter within a specified period time."

Compostability, in other words, is a controlled (manmade or managed) process. "The characteristic of biodegradability in itself does not mean that the material will break down in a reasonable, useful amount of time, nor that it will result in any soil-enriching biomaterial." The term biodegradable is misleading, says the SPC position paper, because it causes consumers to assume that the plastic materials labeled as such will break down into useful bio-nutrients into the soil or water. "Petroleum-based plastics made with the currently available biodegradability additives do not break down in such a manner; to date, these additives have not enabled any plastics to become fully compostable," said SPC.

SPC stated that a major problem with biodegradability is its negative impact on recyclability, an optimum end-of-life scenario for petroleum-based plastics due to two inherent attributes that make recovery ideal: "Their high embodied energy content qualifies their value for controlled energy recovery, and their exceptional durability renders them ideal for recycling." Biodegradability additives, "by design, are intended to compromise that exceptional durability," and to date there is no "satisfactory evidence" that plastics with biodegradable additives will not interfere with the recycling stream. Additionally, says the SPC position paper, "petroleum-based plastics . . . are not bio-based, and the addition of biodegradability additives does not change that characteristic."

Another problem that SPC notes in its position paper is that most additives are "designed to fragment petroleum-based plastics into small pieces in order to make it sufficiently available to the microorganisms that perform biodegradation." While these micro pieces of plastic cannot be seen by the human eye, they contribute to the "environmental impact of micro-pollution." Hence, there is a problem with marketing biodegradable additives as being "less detrimental to the environment" because they may contribute to improper end-of-life disposal and pollution.

People love plastic for its usefulness and longevity; they just want it to disappear when they are done with it. SPC referenced a 2006 study by the American Chemistry Council, which concluded that "when a consumer sees the word ‘biodegradable' on a package, about 80% of consumers believe that the package will completely decompose, regardless of the environment in which the package is disposed."

In other words, people want "magic" plastic that disappears!

That is why in 2008 the state of California banned use of the terms "degradable," "biodegradable," "compostable" and similar verbiage on plastic products, determining that they are "inherently misleading. Given the complex nature of biodegradation . . . and given the intrinsic constraints of marketing claims, including the space on the plastic product, there is no reasonable ability for plastic product manufacturers to provide an adequate disclaimer. . . . Given these and other constraints, and the significant environmental harm that is caused by plastic litter, the use of these terms must be prohibited unless, or until, is established an American Society for Testing and Materials (ASTM) standard specification for the term claimed that has been approved by the legislature," says the California statute. Currently, ASTM D6400 is the standard for biobased plastics.

Oxo-degradable additives have become a popular method to promote biodegradability in plastics in a marine environment. However, studies conducted by the Chico Research Foundation at California State University "have shown that plastics with oxo-degradable additives did not successfully biodegrade in marine environments." Like other biodegradability additives, oxo-degradable additives create "fragmentation" that gives the "appearance" that the plastic has disappeared. However, oxo-degradable additives typically used in plastic bags, do not make the bags compostable, but rather degrade by oxidation. However, there are some claims that oxo-degradable additives are more dangerous to the environment due to the fact that they consist of "salts of transition metals such as iron, cobalt and manganese," leaving traces of these metals in the soil as the oxo-degradable plastics fragment.

A report released by the Pacific Northwest Pollution Prevention Resource Center in Portland, OR, noted that while oxo-degradable plastic manufacturers "claim the material is recyclable and compostable, and degradable in landfill," studies show that "these bags are not compatible with recycling or composting."

Of course those companies who have invested millions of dollars in manufacturing biodegradable additives will argue that biodegradable additives are optimal, while the oxo makers will claim their products make plastics more eco-friendly. It all depends in which basket they've put their eggs. Private companies need to make a good return on their investment, so their sympathies lie with their money.

At this point, we can read all the arguments for and against the various means and methods of getting rid of plastic at the end of its useful life. After all is said and done, however, what we need to do is to look at what solution provides the greatest value and the best return on investment for that solution. We have to look at the input required to recycle, compost, degrade and produce waste-to-energy, and the resulting output in terms of value—both monetary and environmental.

Ultimately there is no single magic bullet that can make plastic disappear. And I don't think that most people want plastics to disappear. What we'd like to see disappear is the litter in our communities and in the world's waterways. And that's not a plastics problem—that's a people problem. An additive that makes plastic litter "degrade" to fragments in 180 days is not exactly what I'd call a solution.

About the Author(s)

Clare Goldsberry

Until she retired in September 2021, Clare Goldsberry reported on the plastics industry for more than 30 years. In addition to the 10,000+ articles she has written, by her own estimation, she is the author of several books, including The Business of Injection Molding: How to succeed as a custom molder and Purchasing Injection Molds: A buyers guide. Goldsberry is a member of the Plastics Pioneers Association. She reflected on her long career in "Time to Say Good-Bye."

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