PLASTIC
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Plastics are materials with a high degree of utility and many safe household uses. They can take the place of other materials that may have more harmful relative impacts. Some plastics, however, are associated with dangers in the manufacturing process, when misused and on other occasions: over their entire lifecycle from manufacture to ultimate disposal. They also comprise a significant fraction o f the entire municipal waste stream.
For these reasons the principals of source reduction, reuse and recycling are just as valid for plastics as for other waste products (see Reasonable Responses below).
| EPA Annual Municipal Solid Waste Characterization Update |
| EPA Municipal Solid Waste Site |
Plastic is made from fractions of natural gas or crude oil changed chemically into solid form. There are two basic types of plastic: thermosetting and thermoplastics. Thermosetting plastics are set to a permanent shape and cannot be softened. These plastics are used primarily for multiple use items, such as dishes and furniture. Thermoplastics are soft when exposed to heat and pressure and harden when cooled. Thermoplastics are the most common type of plastic and are used to make a variety of products.
Following is a list of some of the most common types of thermoplastics, along with their recycling code # (the number that appears in the triangle on the bottom), and their common uses.
Recycling Code |
Plastic Type |
Common Uses |
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#1
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Polyethylene Terephthalate (PETE) | soft drink containers |
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#2
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High Density Polyethylene (HDPE) | milk crates milk jugs and beverage bottles soft plastic margarine tubs |
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#3
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Polyvinyl Chloride (PVC) | auto parts inflatable toys insulation pipes phonograph records shampoo bottles shower curtains some food containers |
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#4
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Low Density Polyethylene (LDPE) | trash bags and other films |
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#5
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Polypropylene |
auto parts |
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#6
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Polystyrene | hot food containers packing materials plastic utensils wall tiles |
While plastics have many practical applications and safe household uses, there are some hazards to plastics that merit their inclusion in the Virtual House website. These are the environmental and health impacts throughout the lifecycle of plastics -- from manufacture to use to ultimate disposal.
Plastics are a significant component of the overall waste stream. In 1998 they
comprised 10.2% by weight and 24 % by volume (USEPA, Polystyrene Packaging Council).
They comprise about 6 percent of all litter. For further information on municipal
waste generation and recycling see USEPA's Characterization of Municipal
Solid Waste: 1999 Factsheet at:
http://www.epa.gov/epaoswer/non-hw/muncpl/msw99.htm
Plastics do not degrade readily. They never totally biodegrade in the environment because their content is not digestible by microorganisms. If they are not picked up by highway workers or volunteers, then they are moved by air and water or accumulate in low areas, waterways, and along fences.
Plastic litter is itself a danger to wildlife. It can kill or injure animals though entanglement in discarded fishing lines, 6-pack rings, and packing bands; or through ingestion of plastic that was mistaken for food.
Toxic chemicals are used in the manufacture of plastics. These chemicals include benzene, cadmium compounds, carbon tetrachloride, chromium oxide, diazomethane, lead compounds, styrene, and vinyl chloride. Some health studies have shown that people who work in, and live near, plants that manufacture plastics and the chemicals used in plastics experience higher incidents of some kinds of cancer than other population (OSHA).
According to the federal Food and Drug Administration, 55% of all packaging
made in the U.S. is for food, with plastics replacing other materials with increasing
frequency. While FDA monitors plastics used in food packaging, it has no regulatory
authority over plastics with "prior sanction," meaning those that
were determined to be safe for use before 1958 (FDA Consumer, 1991).
One exception is Ethyl Carbamate (urethane) for which the FDA has prepared an
Ethyl Carbamate Preventative Action Manual available at:
http://www.cfsan.fda.gov/~frf/ecaction.html
FDA also has a report with recommendations on the use of recycled plastics infood
packaging at:
http://vm.cfsan.fda.gov/~dms/opa-recy.html
A regulatory directory of "indirect additives" that come in contact
with food can be found at:
http://vm.cfsan.fda.gov/~dms/opa-indt.html
The most immediate FDA regulatory contact for plastics in food packaging is:
Ms. Hortense L. Macon
Indirect Additives Branch
Division for Petition Control
Office of Premarket Approval
Center for Food Safety and Applied Nutrition
U.S. Food and Drug Administration
200 C Street S.W.
Washington DC 20204
Phone: (202) 418-3086
Fax: (202) 418-3131
E-mail: HMACON@CFSAN.FDA.GOV
A recent concern regarding plastic consumer products is connected to phthalates, chemicals used to soften plastics and widely used in plastic toys and children's products. Laboratory experiments have linked phthalates to liver and kidney damage, and tumors. In 1998, the Consumer Product Safety Commission requested that manufacturers remove phthalates from products that children are likely to chew and mouth -- such as nipples, pacifiers, teethers, and soft rattles. Most manufacturers were expected to comply with this request by 1999. To check whether a specific toy contain phthalates, contact the Consumer Product Safety Commission at http://www.cesc.gov.
For the reasons stated previously, it important to make careful and sparing use of plastics. The familiar pattern of reduce, reuse and recycle is important.
Plastic recycling has grown significantly in quantity and impact. The annual amount of post-consumer plastic has increased at least sixfold since 1990: to 1.45 million pounds in 1998. This is, however still less than 10% of total annual plastic output; it is estimated that at least 80% of all thermoplastics could be melted down and made into new products.
Incineration is one way to reduce the volume of plastics headed for the landfill. When burned, plastics release more energy than other municipal wastes. When burned in a municipal incinerator, plastics release more energy than other municipal wastes. However, they also contribute many pollutants, including heavy metals (e.g. cadmium, lead) to the incinerator's ash and air emissions. The incineration of PVC releases highly corrosive hydrochloric acid, which contributes to acid rain and may lead to the formation of dioxins in the environment. In addition, the energy value of PET plastic bottles is about 11,000 BTUs per pound. However it takes about 49,000 BTUs to produce one pound of PET. So even ignoring potential pollution, burning plastic as fuel is not efficient.
We know now that nothing breaks down very quickly in the anaerobic conditions of a landfill, so plastics are expected to remain in landfills unchanged for hundreds of years. There is some evidence of decomposition, however. Phthalates are hazardous substances widely used in plastics manufacture. One of these phthalates (di-2-ethylhexyl phthalate) has been discovered in many leachate samples, leading researchers to believe that the chemicals are leaching from plastics buried in the landfill.
Plastics, metals, and glass make up the bulk of the non-organic portion of the municipal solid waste stream. Plastics contribute to the volume of non-organic materials in landfills that are not easily degradeable. However, some companies have been researching and have made considerable progress toward the manufacture of plastics using plants as the raw materials, instead of nonrenewable petroleum. These plastics would degrade in a compost environment. In addition, some plastic products have been manufactured to be susceptible to photodegradation (degradation due to sunlight). Photodegradable plastics are primarily used in items like six pack rings that are often littered and may pose a threat to wildlife.
The potential for all wastes in landfills to decay may be slower than in the environment. Municipal solid waste landfills today are designed to stay dry in order to reduce the production of leachate and prevent groundwater contamination. There is some pilot testing and research of a different kind of landfill, called a bioreactor. In a bioreactor landfill, liquids are added in order to speed up decomposition so that the landfill will reach stability earlier than in a dry environment.
Marie Steinwachs, Office of Waste Management, University of Missouri Outreach and Extension.
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