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.