The New World of Plastics -- Not New Enough
A reporter recently asked me for a comment on a solid waste bill proposed by my Congressman Chuck Douglas (R-NH). I said I was glad Douglas was dealing with an urgent problem, but sorry he had fallen for the knee-jerk solution of degradable plastics. Congress should try to reduce the use of plastics, I added. There should be a hefty tax on them, the revenues from which could go to recycling.
My remark was reprinted in Plastics News magazine. The phone started ringing. Letters from plastics makers poured in, and videotapes, and sample boxes of degradable or recyclable plastics.
Most of my respondents were either frustrated or ebullient. One of the frustrated ones asked plaintively if I'd ever seen a legally enforceable definition of "biodegradable." Another wondered if I knew any studies of exactly what happens, how fast, in plastic degradation. The ebullient ones were about to hit the market with billion-dollar ideas -- a process to recycle PET (polyethylene teraphthalate) soda bottles back into soda bottles, or a scheme to buy back and recycle polyethylene trash bags.
The world of plastics is in a mess these days, because it has made a mess. Polyethylene, polystyrene, polyvinyl chloride, and all the other polys are piling up on roadsides, in the ocean, and in landfills. They are likely to last several hundred years there, after serving us sometimes only for a few hours or weeks -- if indeed they could be said to serve us at all. The primary role of many plastics is to catch our attention in a store, for which purpose they are garishly shaped and colored with, among other things, toxic heavy metals. Environmentalists say the dumps are filling up not with packaging, but with marketing.
Until we noticed the dumps filling up, most of us never thought about the stream of plastics flowing through our lives -- 18 million tons each year, of which 6.5 million tons is packaging, and over three billion dollars' worth is plastic garbage bags in which to throw the other plastics out. Now everyone has panicked. In February 1989 the American Paper Institute counted the following bills pending in state legislatures (not counting the Douglas bill and others at the federal level) -- 66 proposed bans on nonbiodegradable packaging, 12 packaging taxes, 74 source separation and recycling mandates, and 19 requirements that state governments purchase recycled materials.
It's not fair to blame plastics for our trash problem, says the industry. They make up only four to seven percent of municipal solid waste (by weight -- by volume it's more like 20 to 30 percent). But plastics are the focus of most legislation, perhaps because they are the fastest growing constituent of trash, or because they are used for so many trivial purposes, or because they are so nearly immortal.
Immortality is one of the qualities that makes plastics useful, of course. They are impervious to bacteria, acid, salt, rust, breakage, almost any agent except heat, and some of them can even stand up to heat. If they didn't junk up our lives so, we would regard them as miracle substances -- long, long hydrocarbon chains, crafted to take on almost any properties we want. Plastics can be transparent or opaque, hard as steel or pliant as silk, squeezable or rigid, moldable into any conceivable shape.
And, environmentalists would say, they are made from depleting oil and gas, wrested from the ends of the earth, synthesized in energy-consuming, hazardous-waste-generating processes, and disposed of carelessly. They are messy from beginning to end. If we were properly charged the full human and environmental costs of our plastics, we would not eliminate them -- they are far too useful for that -- but we would treat those specialized molecules with the respect they deserve. We would not use them for a few days or hours and throw them out.
The standard environmentalist formula for dealing with precious but polluting materials is simple. Reduce, re-use, recycle, in that order, and then, as a last resort, dispose with care. Of course the plastics industry makes money in inverse order. It is looking for a way to keep us buying millions of tons of plastics each year -- and to have them miraculously disappear when we throw them away.
Therefore industry's favorite answers to the plastics problem are two: incineration and degradation.
As a descendent of petroleum, plastic burns beautifully. Like all hydrocarbons, it combusts into carbon dioxide, a greenhouse gas, plus a host of other pollutants. Some of them derive from additives such as heavy metals (which end up either in air emissions or incinerator ash). Others, like the toxic dioxins and furans, come from high-temperature reactions between hydrocarbons and chlorine. Polyvinyl chloride (PVC) releases so much hydrochloric acid when it burns that it corrodes the incinerator. For that reason one incinerator manufacturer recommends keeping PVC out of incinerated trash.
Incineration can recapture a small fraction of the energy and effort put into making plastics. Degradation doesn't even do that.
Degradable plastics come in two forms: biodegradable and photodegradable. The biodegradable kind mixes the long plastic molecules, which nothing in nature can digest, with starch, which micro-organisms will happily munch away. Depending on the material strength required and the rate of degradation, the starch percentage varies, but it's usually something like six percent starch to 94 percent plastic.
On the side of the road a bottle or bag made of biodegradable plastic slowly falls apart -- into tiny shards of undegradable plastic. The bottle or bag disintegrates, but the plastic is still there. Presumably it is inert and harmless, but no one really knows the implications of a world filled with plastic sand.
In a landfill, biodegradation happens very slowly, if at all. Nothing degrades well in a landfill. William Rathje, an anthropologist from the University of Arizona, drills core samples from old landfills and finds intact food, paper, cloth, 20 years old. He can date the layers exactly, because he can read the newspapers. Landfills are not compost heaps. They haven't the proper air circulation, moisture content, mixture of nutrients, or communities of micro-organisms to encourage natural breakdown.
Of course there's no sunlight in a landfill, either. Photodegradable plastics have chemical links built into their molecular chains that fall apart when hit by ultraviolet radiation in sunlight. The breakdown products are shorter chains, not so much plastic sand as plastic powder. If the plastic is polyethylene and the chains are short enough, soil organisms then appear to take over and digest them -- the only evidence I've seen of real plastic biodegradation. But several months of photodegradation are necessary to begin the process.
Promoters of photo- and biodegradable plastics admit, when pressed, that neither can extend the lives of landfills. They only help with the problem of litter. They are designer molecules to do away with the ugly evidence of our unwillingness to pick up after ourselves.
Recycling at least slows the waste stream and lets the plastics serve us several times before discard. Only about two percent of the plastics we use are now recycled (as opposed to 29% of aluminum and 21% of paper), but that's not because it can't be done. Plastics are the easiest of all materials to recycle. Basically they just need to be shredded and remelted, usually at low temperatures, and reformed. The industry itself grinds and reuses 5 billion pounds of plastic scrap a year.
Two things are in the way of serious plastics recycling -- separation and purification. Consumers can put paper and cans in separate waste containers with relative ease, but they can't tell the difference between polypropylene and polystyrene. Bottlers have set up a voluntary coding system, to be phased in over the next three years, which will stamp resin types on eight-ounce and lar