Wildlife Peril Eased : Degradable Plastics Now on Market

Times Science Writer

The ideal plastic Big Mac container, foam coffee cup or disposable diaper, experts say, should be a lot like Oliver Wendell Holmes's "wonderful one-hoss shay," which ran perfectly for 100 years before it fell apart in one brief moment of chaos.

For example, the foam cup should keep coffee warm until it is empty, then disintegrate into thousands of microscopic pieces, whether in a trash container or on the roadside.

Alas, the cup is better built than the shay. It will last for 100 years, and then it will last for another 100 and another 100. Sunlight won't age it; wind and rain won't weaken it; bacteria won't eat it. The abandoned plastic cup and its kin will persist virtually forever, a blot on the landscape, a hazard to wildlife who eat it or get entangled in it.

But that situation may change soon. Spurred by aesthetic and environmental concerns as well as political pressures, a handful of companies are beginning to produce plastics that are, in effect, booby-trapped so that they can be broken down by sunlight or bacteria.

Limited Use So Far

The new degradable plastics have only limited uses so far: in one brand of trash bags and one out of three six-pack carriers in the United States, and in a small percentage of trash and grocery bags in Europe. But many other companies that already produce plastic packaging materials, bottles, diapers and similar products are testing degradable materials and may introduce such products later this year.

Environmentalists and others hope that this increased interest, along with new laws that limit ocean dumping, could significantly reduce the amount of plastic litter and the danger to wildlife. Plastic materials that could be made degradable now account for less than 2% of all solid waste in the United States, according to Anthony Redpath, president of Eco Corp., a plastics producer in Toronto, Canada.

But the degradable plastics are not without their problems. Manufacturers of plastic products fear that, despite the plastic producers' assurances, the degradables will lose their strength or be attacked by bacteria and fungi prematurely. And they cost 5% to 7% more than regular plastics, Redpath said.

In the Atlantic Ocean off the northeast coast of the United States, each square mile has more than 46,000 pieces of plastic floating on the surface, including ropes, fishing nets and plastic sheeting, according to a 1987 survey by the Woods Hole Oceanographic Institution in Massachusetts.

Abandoned fishing nets and lines entangle propellers of commercial vessels, necessitating expensive, time-consuming repairs.

"The irony is that most of this plastic is legally dumped by other vessels, who are fouling their own environment," said marine biologist James M. Coe, head of the National Oceanic and Atmospheric Administration's Office of Marine Entanglement. Commercial and fishing vessels around the world dump nearly 500,000 tons of trash each year, according to the National Academy of Sciences.

The impact on marine life is especially severe, Coe added. As many as 30,000 northern fur seals, more than 5% of the population, are killed each year by becoming entangled in plastic ropes, nets, and shipping bands. All seven species of marine turtles are considered endangered or threatened, in large part because of ingestion of plastic litter.

Such pollution at sea may be reduced by an international agreement banning all dumping at sea by commercial vessels and fishing boats. The treaty was negotiated in 1973, and was approved by the U.S. Congress last November. It is to take effect one year after it is ratified by at least 15 countries, representing half the world's shipping tonnage. The U.S. approval fulfilled those qualifications, and the treaty is to take effect next November.

Localities Consider Bans

Some localities are also considering bans on the use of non-degradable plastics. The Berkeley City Council has asked merchants to halve their use of non-degradable food packaging by 1990. Suffolk County, N.Y., has proposed a ban on fast-food packaging made from two types of plastics, and New York state has asked McDonald's, the country's largest fast-food chain, to phase out all plastic packaging.

And the United States is not alone in its interest in degradable plastics. Italy, for instance, has mandated that all plastic grocery and shopping bags be degradable by 1990, and other European countries are considering similar laws. The cities of Florence and Venice banned non-degradable bags last summer.

Degradability, ironically, is the antithesis of the properties, especially inertness and durability, for which plastics have been prized since they were developed near the end of World War II.

The extremely long polymer molecules that comprise plastics cannot be digested by naturally occurring bacteria or other microorganisms in the environment and are not affected by sunlight.

To make such plastics biodegradable, chemists must place tiny time bombs in the polymers by incorporating molecules that "detonate" when they are exposed to sunlight or bacteria, breaking the plastic into smaller molecules that can be degraded naturally within weeks or months.

That process is a delicate balancing act: if the time bombs go off too soon, the package's contents may be ruined; too late, and the advantage of degradability is lost. Much of the research on degradable polymers involves determining precisely the correct amount of additives required to achieve a particular product lifetime.

Six-Pack Carriers

The prime example of this approach is the plastic carrier used for six-packs of soda and beer. Once discarded, the carriers can strangle animals and fish or entangle them in such a way as to prevent them from eating.

Since 1977, 11 states--including California, in 1982--have mandated that the carriers be made of degradable plastics. Because of quirks in the distribution system, about one-third of all states now receive drinks in degradable carriers.

"Common sense says this has to be helping the situation with wildlife," said Kathy O'Hara, a marine biologist with the Center for Environmental Education in Washington. The only available evidence about the laws' effects comes from beach cleanups conducted last year, she said.

In California and Oregon, which require use of degradable carriers, volunteers found an average of 15 carriers per mile and four carriers per mile of beach, respectively. In Texas, which has no such law, the average was 106 per mile.

The carriers are photodegradable--they are broken down by ultraviolet light from the sun. That is achieved by chemically inserting carbon monoxide molecules at regular intervals in the polymer chains. The carbon monoxide absorbs ultraviolet light and breaks apart, weakening the plastic.

Sunlight Necessary

Because indoor lights do not produce ultraviolet radiation and windows in stores screen it out, breakdown does not begin until the carriers are left outside in sunlight.

During the summer in Southern California, when the amount of sunlight is the greatest, the carrier will begin to lose its strength within three days. "It still (looks like) a carrier . . . but it is no longer good as a package," said materials engineer Harry F. Pillman of Illinois Tool Works of Itasca, Ill., which manufactures the carriers. After 250 hours of exposure to sunlight, it is too fragile to be handled without crumbling.

The only other consumer products in the United States made of degradable plastics are Good Sense trash bags, sold in the East by Webster Industries of Peabody, Mass. The photodegradable bags have been sold in the Northeast for six years, but the company has been expanding its marketing area in response to new environmental concerns, said spokeswoman Donna McEntyre.

The bags are sold for about 10 cents per box less than competitive products, and have as much as 10% of the market in some northeastern cities such as Boston. The product was purposely priced low in order to gain a market share, McEntyre said.

Eco Corp. manufactures an additive that makes plastics photodegradable. Grocery and trash bags made with the additive account for about 1% of total bag sales in Europe, Redpath said. Safeway Corp. has ordered 50 million grocery bags for use in selected stores in Western Canada.

Approved in Canada

Plastics made with this additive have been approved for use with food products by Health and Welfare Canada, the Canadian counterpart of the U.S. Food and Drug Administration, and the company has filled an order for 2 million foam cups that will be used for dispensing Coca-Cola in convenience stores, Redpath said. Eco Corp. is working with other manufacturers who hope to produce soda straws, fast-food packaging and condoms, he added.

A new type of biodegradable plastic that shows great promise for packaging materials and disposable products such as diapers is made by mixing inexpensive cornstarch with conventional plastics--a technique pioneered by chemist Felix H. Otey of the U.S. Department of Agriculture's research station in Peoria, Ill. The starch-plastic blend can be melted and molded into products just like pure plastic.

When a product made from the blend is discarded, the starch is eaten away by the bacteria and fungi that are ubiquitous in the soil and air. This weakens the plastic so that it breaks into small pieces.

"We can make a seedling pot that will break apart underground in 20 days, or we can make an agricultural mulch film that will last for four months, then catastrophically degrade so it can be (plowed) into the ground," said materials scientist Richard P. Wool of the University of Illinois at Champaign-Urbana. Wool is director of research for Agri-Tech Industries Inc., of Gibson City, Ill., which has an exclusive license on the Agriculture Department patents.

Although no commercial products are yet made from these starch-based plastics, more than 100 manufacturers of trash and grocery bags, food packaging, diapers and hygienic products are experimenting with them, Wool said. He expects trash bags made from the plastics to be marketed before the end of this year, and perhaps agricultural mulch film.

Farmers use about 125 million pounds of mulch films every year, spreading it between rows of crops to inhibit weed growth and hold heat and water in the soil. But the cost of collecting and disposing of the film at the end of the growing season is greater than the cost of the films themselves, Wool said.

Ideal for Fast Foods

Wool also believes that the starch-based plastics would be ideal packaging for fast foods, but Agri-Tech must first seek approval from the FDA. A McDonald's spokesman would say only that the company is "exploring all alternatives" and that it is concerned about increased costs.

Another cornstarch-and-plastic blend that uses technology different from Agri-Tech's is made by St. Lawrence Starch Co., Ltd., of Mississauga, Canada. St. Lawrence also has about 1% of the European market for trash and grocery bags, said business development manager Wayne J. Maddever, and Bio-Guard trash bags made from it went on sale in Canada last month.

St. Lawrence Starch also hopes to begin using it for milk bottles and bottles for the company's own corn oil and corn syrup, Maddever said.

Copyright © 2019, Los Angeles Times
EDITION: California | U.S. & World