Pollution and hazards from manufacturing
The most obvious form of pollution associated with plastic packaging is wasted plastic sent to landfills. Plastics are very stable and therefore stay in the environment a long time after they are discarded, especially if they are shielded from direct sunlight by being buried in landfills. Decomposition rates are further decreased by anti-oxidants that manufacturers commonly add to enhance a container’s resistance to attack by acidic contents.
Plastics also put a big chemical burden on the environment. The Oakland Recycling Association commissioned an analysis of the toxic chemical burden that relied heavily on information from EPA data, especially the Toxics Release Inventory. These data were limited because manufacturers within the “miscellaneous plastics sector” did not file reports. Nevertheless, the information available showed that most toxic releases went into the air, and the plastics industry contributed 14% of the national total. Of the top ten manufacturers ranked by total releases, seven made plastic foam products. Significant releases of toxic chemicals included :
- methylene chloride
- methyl ethyl ketone
- 1,1,1 trichloroethane
Other major emissions from plastic production processes include sulfur oxides, nitrous oxides, methanol, ethylene oxide, and volatile organic compounds.
Less visible but very serious is the pollution generated by producing plastic resin. As ethylene is polymerized, the reactive mixture is scrubbed with dilute aqueous caustic solutions that become high-volume pollutants. The refining process uses waste-minimization methods, but point-source air emissions are still high because of inherent difficulties in handling large flows of pressurized gases. Manufacturing PET resin generates more toxic emissions (nickel, ethylbenzene, ethylene oxide, benzene) than manufacturing glass. Producing a 16 oz. PET bottle generates more than 100 times the toxic emissions to air and water than making the same size bottle out of glass.
Producing plastics can be hazardous to workers, too. Serious accidents have included explosions, chemical fires, chemical spills, and clouds of toxic vapor. These kinds of occurrences have caused deaths, injuries, evacuations and major property damage. A review of the US EPA’s data base of 10,000 accidents and spills from 1980-87 shows that nearly 1,600 (16%) of industrial accidents were associated with producing plastics or plastic constituents.
Negative health effects – toxic additives, migration into food
In addition to creating safety problems during production, many chemical additives that give plastic products desirable performance properties also have negative environmental and human health effects. These effects include direct toxicity, as in the cases of lead, cadmium, and mercury; or carcinogens, as in the case of diethyl hexylphosphate (DEHP). Problem chemicals are used as plasticizers, antioxidants, colorants, flame retardants, heat stabilizers, and barrier resins. A single resin type might be mixed with many such additives, adding complexity to the chemical composition and possibly generating new classes of incompatible resins within the grossly simplified SPI resin code. An example of internal incompatibility is resin type 2, noted earlier as a recycling problem because the blow-mold resin grades and injection-mold grades must be separated for most primary recycling applications.
People are exposed to these chemicals not only during manufacturing, but also by using plastic packages, because some chemicals diffuse (migrate) from the packaging polymer to the foods they contain. Migration potential exists for traces of monomers, oligomers, additives, stabilizers, plasticizers, lubricants, anti-static nucleating agents, and reaction products of the polymer or its additives. Such substances may be toxic.
Diverting solid waste
Curbside plastic collection programs are driven in part by a wish to minimize municipal solid waste. Indeed, most legislation dealing with discarded containers has focused on creating mechanisms that would divert municipal plastic waste from incinerators or landfills. These initiatives include container deposit laws and landfill use-reduction laws. Although important, such measures do not solve the problem of over-packaging or reduce the production of plastic packaging. Only source reduction can do this. As discussed in section 8, Germany recognized the need to implement aggressive source reduction and passed a law requiring all manufacturers to arrange to pick up discarded packaging, usually at the point of sale, such as the supermarket. This requirement has encouraged industry to reduce packaging.
In addition, as noted earlier, providing recycling for plastic containers may actually encourage their use and increased production. But as plastic packages become less standardized and more complex, recycling becomes more difficult. Already, many plastic packages that consumers have expected to be recycled must be landfilled. Therefore the diversion may not be as effective as proponents intend. (See misconceptions 1 and 2 in section 10 below.)