Plastic products are printed with numbers 1–7 depending on the type of resin. Type 1 plastic, PET (or PETE): polyethylene terephthalate, is commonly found in soft drink and water bottles. Type 2, HDPE: high-density polyethylene is found in most hard plastics such as milk jugs, laundry detergent bottles, and some dishware. Type 3, PVC or V (vinyl), includes items like shampoo bottles, shower curtains, hoola hoops, credit cards, wire jacketing, medical equipment, siding, and piping. Type 4, called LDPE, or low-density polyethylene, is found in shopping bags, squeezable bottles, tote bags, clothing, furniture, and carpet. Type 5 is PP which stands for polypropylene and makes up syrup bottles, straws, Tupperware, and some automotive parts. Type 6 is PS: polystyrene and makes up meat trays, egg cartons, clamshell containers and compact disc cases. Type 7 includes all other plastics like bulletproof materials, 3- and 5-gallon water bottles, and sunglasses.Types 1 and 2 are the most commonly recycled.
Recycling is a process using materials (waste) into new products to prevent waste of potentially useful materials, reduce the consumption of fresh raw materials, reduce energy usage, reduce air pollution (from incineration) and water pollution (from landfilling) by reducing the need for "conventional" waste disposal, solid waste management and lower greenhouse gas emissions as compared to plastic production. Recycling is a key component of modern waste reduction and is the third component of the "Reduce, Reuse, Recycle" waste hierarchy.
However, comparing the market cost of recyclable material with the cost of new raw materials ignores economic externalities—the costs that are currently not counted by the market. Creating a new piece of plastic, for instance, may cause more pollution and be less sustainable than recycling a similar piece of plastic, but these factors will not be counted in market cost. A life cycle assessment can be used to determine the levels of externalities and decide whether the recycling may be worthwhile despite unfavorable market costs. Alternatively, legal means (such as a carbon tax) can be used to bring externalities into the market, so that the market cost of the material becomes close to the true cost.
Origins of recycpling
Recycling has been a common practice for most of human history, with recorded advocates as far back as Plato in 400 BC. During periods when resources were scarce, archaeological studies of ancient waste dumps show less household waste (such as ash, broken tools and pottery)—implying more waste was being recycled in the absence of new material.
In a 2007 article, Michael Munger, chairman of political science at Duke University, wrote that "if recycling is more expensive than using new materials, it can't possibly be efficient.... There is a simple test for determining whether something is a resource... or just garbage... If someone will pay you for the item, it's a resource.... But if you have to pay someone to take the item away,... then the item is garbage."