Although plastics have had a remarkable impact on our culture, it has become increasingly obvious that there is a price to be paid for their use.

The first controversy arose in the late 1950s and early 1960s.  There were a number of incidents where small children crawled into plastic bags used by launderers to cover clothing, and suffocated.  The plastics industry managed to fend off trouble by launching a massive public-education campaign.

By the late 1960s, plastics were increasingly seen as a symbol of an outdated 1950s consumer culture.  The term "plastic" became an insult, used to describe someone thought of as soulless.  At the end of the 1960s, the Beatles would even sing of "Polyethylene Pam," a "go-getter" who would do anything to get ahead.

This was partly just a fashion statement, since plastics remained in widespread use anyway, and in many cases were much more effective and environmentally benign than alternative materials.  However, this led to a problem as well, since the consumption of massive amounts of plastic goods led to a massive problem with litter and waste disposal.

Plastic was almost too good, as it was durable and degraded very slowly. In some cases, burning it could release toxic fumes.  There was also the problem that manufacturing plastics often created large quantities of nasty chemical pollutants, and depleted the Earth's bounded supply of fossil fuels.

By the 1990s, plastic recycling programs were common in the United States and elsewhere.  Thermoplastics can be re-melted and reused, and thermoset plastics can be ground up and used as filler, though the purity of the material tends to degrade with each reuse cycle.  There are methods by which plastics can be broken back down to a feedstock state.

Products such as automobiles are now being designed to make recycling of their large plastic parts easier.  To assist recycling of plastic disposable items, the Plastic Bottle Institute of the Society of the Plastics Industry devised the now-familiar scheme to mark plastic bottles by plastic type.  A recyclable plastic container using this scheme is marked with a triangle with three "chasing arrows" inside of it, which enclose a number giving the plastic type: PETE, HDPE, PVC, LDPE, PP, PS, and OTHER.

 

Unfortunately, recycling plastics proved difficult. The biggest problem with plastic recycling is that it is difficult to automate the sorting of plastic waste, and so it is labor-intensive.  While containers are usually made from a single type and color of plastic, making them relatively easy to sort out, a consumer toy like a cellular phone may be made of many small parts consisting of over a dozen different types and colors of plastics.  As the value of the material is low, recycling plastics is unprofitable.  For this reason, the percentage of plastics recycled in the US is very small, somewhere around 5%.

 

Research has been done on "biodegradable" plastics that break down with exposure to sunlight.  Starch can be mixed with plastic to allow it to degrade more easily, but it still doesn't lead to complete breakdown of the plastic.  Some researchers have actually genetically engineered bacteria that synthesize a completely biodegradable plastic, but this material is expensive at present.

So far, these plastics have proven too costly and limited for general use, and critics have pointed out that the only real problem they address is roadside litter, which is regarded as a secondary issue.  When such plastic materials are dumped into landfills, they can become "mummified" and persist for decades even if they are supposed to be biodegradable.

 

There have been some success stories. The Courtald concern, the original producer of rayon, came up with a revised process for the material in the mid-1980s to produce "tencel." Tencel has much superior properties to rayon, but is still produced from "biomass" feedstock, and its manufacture is extraordinarily clean by the standards of plastic production.  Whether the use of plastics can be made completely consistent with environmental quality demands, still remains to be seen.

[时间：2003-06-05  作者：Bisenet  来源：Bisenet]