Plastics Industry Struggles With Biodegradability

New ASTM regulations promise to set clear definitions, enabling scientists to develop truly degradable plastics WASHINGTON--The growing public demand for truly biodegradable plastics has gone unfulfilled, in part because of a lack of agreement on what "biodegradability" means. But a new and comprehensive set of standards to define and measure such natural polymers, due out this spring, promises to help clear up the confusion within the scientific community as well as society at large. "The new standards will help scientists to design new biodegradable plastics," says Ramani Narayan, chairman of the subcommittee on environmentally degradable plastics for the American Society for Testing and Materials (ASTM), which is developing the standards. Scientists across a broad spectrum of disciplines, from physics to ecology to chemical engineering, working in university and industry labs as well as at government research centers, expect the standards to improve their ability to design new plastics from natural substances. Scientists "will look up the ASTM procedure to do a test and, by seeing if the results fit specific criteria, they will determine if the plastic is biodegradable," says Narayan, who is also a chemical and biochemical engineer at Michigan State University in East Lansing. The need for such standards was the driving force behind the creation two years ago of the Polymer Degradation Research Consortium at the University of Lowell in Massachusetts. "The consortium was founded because of the need for scientific research on truly degradable materials, as opposed to starch-filled plastics," says Stephen McCarthy, a plastics engineer. "There was a lot of data, but none of it was comparable or realistic. Someone might say, for instance, that a plastic is degradable because it supports a fungal growth on a plate. But that could be just due to a plasticizer in the material, while the plastic itself remains inert." McCarthy and his colleagues are working on wastebasket-size models of landfills, marine environments, and compost heaps. That information, as well as data and suggestions from five other labs and a number of government agencies, is being used to formulate the ASTM standards. The society will publish the first set of seven broad definitions for such terms as hydrolytically degradable and photodegradable, as well as one set of testing specifications for photodegradation, this April. Eleven additional testing methods, as well as more detailed definitions for plastics deposited in landfills, in compost heaps, and by the road, will be released as ASTM scientists continue to monitor materials for loss of tensile strength, chemical structure changes, and the amount of carbon converted to carbon dioxide and biomass. Although scientists have generated considerable data on these materials, the significance of the information is not always clear. And without widely accepted definitions, claims of the existence of environmentally friendly plastics have turned out to be premature. Many scientists in the field hope that a universal set of standards will give the government a more realistic set of goals and will address a number of other problems that plague researchers in this area. "These new standards will certainly expedite research," says Thomas J. Galvin, consultant and former biopolymers manager for ICI Americas Inc. in Wilmington, Del., which has developed a new plastic from bacteria. "Scientists will be on a level playing field at last, and we'll be able to compare work." The new biopolymers being developed by Galvin and other researchers are made, unlike their pervasive petroleum-based cousins, from natural sources such as starches and sugars. Under the right conditions, these starch- and sugar-based bioplastics will degrade. But progress has been slowed by advertisers' claims and by the public's misunderstanding of research, some scientists complain. "So much was made of biodegradable polymers it just ended up hurting this area," says James Kinstle, who manages chemical and polymer research at the James River Corp., a paper and packaging company in Neenah, Wis.20"You can't give people such high hopes and then dash them and not lose some credibility." Research has also been impeded by a lack of testing standards and definitions of even the most basic terms. "Traditionally the tests for polymers have been to see how resistant they are to degradation," says Michael Gould, director of research at the Biotechnology Research and Development Corp. in Peoria, Ill., and formerly with the Agriculture Department's Biopolymer Research Unit there. "In this new situation, where you want natural polymers to be degradable, everyone is making their measurements in a different way. There is no accepted method for uniform testing, which complicates comparing data from one lab with data from another." An object buried in a moist, aerobic environment, such as a compost heap, may decay, for example. But that same object, placed in a dry, anaerobic landfill, may remain inert, says Gould. "People at scientific meetings get very frustrated and confused," he adds. "Everyone has a ruler that is a different length, and we are all trying to agree on what an inch is." Communication is further hampered, say some scientists, by the interdisciplinary nature of the work. Any field that brings together biochemists, ecologists, organic chemists, marine biologists, physical chemists, microbiologists, and materials engineers also must figure out a way to overcome the differences in vocabulary among the disciplines. "What does `degradable' mean?" asks Gould. "If I tell a physical chemist that this plastic degraded, he would think it has lost tensile strength. But a biologist would say it is converting large molecules into small molecules. And the average person thinks that a product labeled `biodegradable' should just degrade into dust, like leaves on the ground, and blow away." This confusion of terms, though typical of any new area of research, is hampering development of bioplastics, say some experts. "I run a lot of symposia where I bring together bacteriologists and enzymologists, for example, and the language is so different," says Kinstle, who is also chairman of the American Chemical Society's Division of Polymeric Materials. "Eventually the poor communication slows down being able to get the right teams together, impeding research at research institutes, companies, and universities." While it's clear that a lack of a common vocabulary makes it difficult for scientists to compare data, some scientists also claim that research itself has been slowed by the absence of testing standards. "We have materials we would like to test, but we are really not sure how to do it," says William Daly, a polymer chemist at Louisiana State University in Baton Rouge, who is developing polymers from chitin, the tough outer shell of crabs and other crustaceans. "The standard in the past has been to bury it in your garden for six months, and we haven't been able to get a protocol or guidelines to replace that." The lack of universal standards has also contributed to the public's misunderstanding of bioplastics. And that confusion results in disillusionment, which leads to criticism of the scientific community. Until five years ago, biopolymers were used mostly for biomedical materials, such as sutures for surgery. But a revived environmental consciousness across the United States. States inspired companies to produce trashbags, diaper coverings, and cups, all from natural polymers. Unfortunately, this demand for environmentally friendly products pressured some scientists into discussing their research too soon. "The whole field has suffered because of the enormous amount of attention that was placed on these things in the public eye," says Gould. "This happens all the time when you have a very complicated problem. The media are looking for simple answers, and the public ends up being misled into thinking there is an easy answer." Without a clear set of definitions, advertisers were quick to use the term "biodegradable" to help sell their products. But those claims did not always square with reality. A plastic bag that degrades by the side of the road or in a compost heap, for instance, won't decay at all in a typical municipal landfill, where even 15-year-old carrots have been unearthed in near-perfect condition. "There is a public conception that a landfill is a giant fermenter and that things in there rot and decay and go back into the biosphere," says Gould. "But in fact that doesn't happen. Most landfills are set up to minimize biological activity." The effect of overenthusiastic advertising claims was exacerbated by the youth of the science. In the first years of biopolymer research, much of the focus was on starch blends, in which cornstarch is mixed in with a more traditional plastic. When the starch decays, the original product breaks up into little pieces of nondegradable plastic. Scientists and government groups wondered whether such items could really be called biodegradable. Recently, however, scientists have made headway with a so-called second generation of biopolymers that contain no synthetic plastics. But much of the work on these plastics, derived from substances such as corn and potato starch or shrimp and other crustaceans, or produced by bacteria or fungi is still in its infancy. And scientists worry that the premature claims of a few years ago could hurt research into these products. "Two years ago a lot of people came on as if biodegradable polymers were some kind of panacea," says Kinstle. "Legislation and funding was swayed by that push into the starch-filled plastics. "When people figured out they wouldn't work, it hurt the whole field, just at a time when we needed more attention to the other areas of biodegradable plastics." The enthusiasm, for example, led to public and government claims of false advertising when expectations weren't met. Last November, a 10-state task force of attorneys general released a "Green Report" accusing advertisers of making claims that are "trivial, confusing, or even misleading." And early last year, the Federal Trade Commission began to investigate 20 manufacturers who were advertising their products as "biodegradable," "photodegradable," "recyclable," or "ozone friendly." Such abuses helped both scientists and the government to realize that a reliable set of standards was needed. The Green Report called for definitions for marketers to follow. Both the FTC and the state attorneys general have urged the ASTM to develop its guidelines. Sen. John Glenn (D-Ohio), who two years ago introduced a bill to induce industry to develop and market degradable plastics, now believes that a set of standards must be developed first. "At the hearings [to discuss the 1988 bill and a similar one a year later] there was much controversy on what is degradable and what is non-degradable," says a Senate staffer. As a result, says the aide, Glenn now plans to introduce a bill that would establish another committee to develop standards, definitions, and testing methods for degradable plastics. Whatever their specific content, the new standards will require researchers working in this field to make a sharp break from the past. "For years we scientists have been taking molecules from oil to build products," says ASTM's Narayan. "Now we have to think about the best way to take apart plastics."

Plastics Industry Struggles With Biodegradability

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