Drastic Plastic

Forest and Bird, Volume 21, Issue 3, 1 August 1990, Page 6

Drastic Plastic

THE MUCH HERALDED ANSWER to the plastic waste problem — biodegradable or photodegradable plastic — has been given the thumbs down overseas, on the grounds that the plastic does not in reality degrade. Composting experiments conducted in the United States suggest that even under the ideal decomposition setting of a compost heap, the kind of degradable plastic now available merely weakens, sometimes breaking into small pieces. Although the plastic changes form, most of its volume remains. Degradable plastics were hailed as a solution to the problem of marine life being entangled in plastic six-pack holders, or ingesting plastic bags. But when supposedly biodegradable plastic bags were recently placed in lobster pots and submerged, they simply did not degrade in saltwater. That doesn’t mean to say degradable plastic is a hoax. In fact ICI has just developed the first truly degradable plastic. Instead of being derived from oil, the polymer, called PHB, is extruded from the natural excretions of bacteria. The bacteria can live on sugar so the whole process is completely renewable. The

sad fact is that ICI has been unable to sell any PHB because the current price of sugar is so high. Combined with the capital costs of setting up a production plant, it couldn’t hope to compete against conventional plastic. The question of Forest & Bird magazine wrapping is frequently raised by readers. One option is to revert to manilla envelopes: the consequence would be a doubling in the price of despatch. However, it’s questionable whether such a move would necessarily assist the environment, as brown paper is heavier and bulkier in landfills and more polluting in its manufacture than polyethylene, a non-toxic form of plastic. Contrary to accepted wisdom, paper does not break down easily in landfills, graphically demonstrated by US "garbologist" William Rathje who has discovered buried copies of newspapers printed 40 years ago that "looked so fresh you might read one over breakfast."