Biodegradable plastics have gotten cheaper and more reliable, but some still object to their ecological footprint, according to The Christian Science Monitor Paper, plastic... or biodegradable? Yes, get ready to add a third option at the grocery store checkout line as biodegradable plastics enter the mainstream consumer market.

It is hard to imagine that the plastic grocery bag made its debut only 30 years ago. But now, even in Antarctica, scientists regularly find them blowing about.

The problem is that, unlike many other overnight sensations, plastics stick around. It can take roughly 1,000 years for some petroleum-based plastics to disintegrate. And when they do disintegrate, traditional plastics leave behind a messy legacy of fragments and chemical residues that get absorbed into streams and soil. In the meantime, they clog landfills and rivers, or kill whales and sea turtles t hat mistake them for food. With up to 1 trillion plastic bags manufactured annually and 2.7 million tons of plastic used just to bottle water each year, concern is rising worldwide.

Enter bioplastics, designed to degrade into an ecofriendly mix of water, carbon dioxide, and biomass. While biodegradable plastics have been introduced before in the past 20 years, they have failed to achieve widespread use due to their inferior strength and higher cost. But this is changing, says Steve Mojo, executive director of the Biodegradable Products Institute (BPI) in New York City.

"In the last decade, we‘‘ve seen that through improved production technology . these materials have become comparatively durable and affordable, without leaving behind the remnants that petroplastics do," says Mr. Mojo.

While the cost of producing bioplastics ranges from as little as 10 percent more to many times that of traditional plastics, bioplastics companies have seen an i ncreased demand due to rising environmental concerns among consumers and changing environmental regulations. The improved strength, meanwhile, is great news to any trash collector or conscientious pet owner who knows the hazards of an inferior plastic bag.

But when it comes to disposal, not all bioplastics are created equal, leading to confusion for consumers and waste-management groups alike. Bioplastics are not uniform in their ability to decompose under different conditions. While some brands can biodegrade within a few months in backyard compost piles, others require several months at industrial composting facilities.

NatureWorks, the largest producer of bioplastics (they make about 300 million pounds per year), distributes beverage bottles made from polylactic acid (PLA), a hydrobiodegradable polymer. Its bottles are touted as biodegradable within 100 days - but only if it reaches an industrial composting plant with high humidity and temperatures.< br />
According to the Container Recycling Institute, such bottles are unlikely to end up at such plants; of the estimated 25 billion single-serving, plastic water bottles Americans will buy this year, 8 out of 10 (22 billion) end up in landfills. Many stores do not accept returned PLA plastic for recycling or composting. And given that scarcely more than 100 industrial composting facilities exist nationwide, some question the benefits of bioplastics largely destined to end up as litter or in dumps.

In contrast to NatureWorks, Mirel, a product line of Metabolix Inc., says its products - including bags, gift cards, and razor-blade handles - will decompose in a backyard composter within two months, and within four months in soil, fresh water, or salt water.

Currently, both companies‘‘ products are primarily made of modified corn feedstock, as opposed to petroleum byproducts. Ultimately, the natural polymers biodegrade as microorganisms consume them. W hile this source of plastic seems earth friendly, some environmentalists say the footprint of co