CAMBRIDGE, Mass. - Target offers shoppers an unusual message about its gift cards at some stores, advising that they are biodegradable. "Just make sure you spend them first," the displays conclude.
This isn't just a marketing gimmick. Plastics made from corn and other plants are carving a tiny niche from the market for conventional petroleum-based plastics and being touted as green alternatives for everything from bulk food containers to lipstick tubes and clothing fiber - as well as gift cards.
So-called "bioplastics" offer the world a way to wean itself off oil, and most biodegrade to varying degrees. But their makers' green argument is complex, and environmentalists are cautious with support.
Manufacturing bioplastics produces carbon dioxide, which contributes to global warming. The materials are made from crops - corn, switchgrass, sugar cane, even sweet potatoes - that require land and water to grow. Some sound alarms because genetically modified organisms are used to spur the fermentation that creates them. And recycling presents still other pitfalls.
They also can cost three times more than conventional plastics, which gives businesses pause about adopting them. Yet, until bioplastics expand beyond their current tiny fraction of the overall plastics market, the road to popularity is expected to be rough.
"It's almost a chicken-and-egg scenario," said David Cornell of the Association of Postconsumer Plastic Recyclers. "It might someday
'bioplastics' reach that critical mass, but it has to happen very quickly, because in the meantime it can be a nuisance for us."
Bioplastics' main benefit would be to reduce the share of U.S. petroleum consumption that goes into plastic. The types that are biodegradable also could help compensate for the country's slow progress in recycling - only about 6 percent of plastic made in the U.S. was recycled in 2005, according to the U.S. Environmental Protection Agency.
Bioplastics also lack toxins like polyvinyl chloride that have raised health concerns.
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"This is a promising new technology that faces some challenges," said Mike Schade of the Center for Health, Envi-ronment & Justice, a Falls Church, Va.-based nonprofit.
The market's newest entrant is Mirel, from Cambridge-based Metabolix Inc. It more easily biodegrades than rival materials and, unlike others, can break down in a backyard compost bin. Its first consumer application came in July when Target Corp. began using it in gift cards at 129 stores. Metabolix is talking with potential clients about dozens more applications for Mirel.
Agricultural processor Archer Daniels Midland Co. provides corn feedstock for making Mirel, which requires genetically engineered bacteria to aid in fermentation.
The most widely used bioplastic, NatureWorks - a product of a subsidiary of Minnesota-based Cargill Inc. - also is corn-based and biodegradable. NatureWorks already is used in dozens of products.
No figures are available on overall bioplastics production, but bioplastics makers acknowledge the products occupy a tiny niche in the global plastics market, which totals $250 billion and produces 360 billion pounds a year.
For most biodegradable bioplastics, including NatureWorks, an industrial compost plant is recommended - facilities that are few and far between. Metabolix says Mirel will decompose in a backyard compost within two months and about twice as slowly in soil, rivers, lakes or the ocean. But very few Americans compost, and most who do try not to include even paper products, let alone unfamiliar bioplastics.
And, just as different types of petroleum-base plastic can't be mixed in recycling, bioplastics should not be mixed with any conventional plastic because even tiny quantities can irreparably contaminate some melted petroleum-based plastics that have higher melting points, Cornell said.
"The sustainability concept is taking hold broadly, including in the corporate sector," said McLaughlin. "But these materials face a long road gaining acceptance."
A major bump on that road will be their cost. But, in another chicken-and-egg paradox, growing the market for bioplastics is key to bringing down their price, industry leaders said. NatureWorks says its production costs are just 10 to 20 percent above those of conventional plastics. Companies buying Mirel pay about $2.50 a pound, compared with 70 cents to 90 cents for petroleum-based resin, although the price difference is expected to shrink as quantities grow and oil prices rise.
Tamara Nameroff, acting director of the American Chemical Society's Green Chemistry Institute, said being as good as the product it replaces is not good enough for any green product.
"You have to show a cost advantage to what it's replacing," she said. "The idea that people just want to purchase environmentally friendly products has been demonstrated in some markets, but not universally."