Comparing Plastic Types
Compostable Materials

Comparing Plastic Types

Over twenty different types of plastic are produced and consumed by industrialized economies. These plastics can be sorted into seven different categories, according to the types of resins used to produce them, summarized in the table below. Plastic products are typically labeled with the numbers that correspond to these categories. The different categories carry different levels of recyclability and different types of toxicity.

Characteristics of Plastic Resins in Seven Different Categories

Resin Codes1 Descriptions Typical Products Health and Environmental Concerns
Polyethelene Terephthalate (PET, PETE)
Clear, tough, strong moisture barrier

Drink bottles, food jars, heatable food trays, textiles and films Relatively safe for consumer use, but PET containers can leach toxins into liquid contents if the containers are hot, exposed to sun, or old.2, 3 Small doses of one of these toxins, antimony, can cause headaches and dizziness.3Another category of these toxins, Phthalates, comprises known hormone disruptors.3 Manufacturing PET resin generates toxic air emissions in the form of nickel, ethylbenzene, ethylene oxide and benzene.2, 4 Although technically relatively easy to recycle, in 2006 only 23% of used PET bottles were recycled and only 5% of new PET bottles came from recycled content.5
High Density Polyethelyne (HDPE)
Stiff, strong liquid barrier, resistant to solvents
Bottles for milk, juice, shampoo, detergents, etc; shopping bags, cereal box liners; pipe, wire covering Relatively safe for consumer use, but HDPE containers can leach toxins into liquid contents if the containers are hot, exposed to sun, or old.2 One of these toxins, Bisphenol A (BPA), is a known hormone disruptor.6
Polyvinyl Chloride (PVC, Vinyl)
Chemical and weather resistant, stable electrical properties, high strength and clarity
Rigid packaging, shrinkwrap; pipe, siding, window frames; blood bags and medical tubing; insulation, carpet backing Try to avoid! Contains Bisphenol A, phthalates, and dioxins, which may interrupt hormonal activity, and toxic vinyl chloride, which is carcinogenic.2 Some PVC plastic wraps contain the carcinogen DEHP.2 Production of PVC releases carcinogenic vinyl chloride gas and dioxins into the environment.2 Prolonged exposure to vinyl chloride gas in the workplace can damage the liver, immune system, and nervous system.7 Not only is PVC inherently dangerous in its basic form, but it also needs a large amount of lead to stabilize it.2 PVC contains a variety of additives and lacks a uniform composition, which makes it far less recyclable than other plastics, resulting in a post-consumer recycling rate of less than 1%.8 PVC is a strong contender for being the most environmentally hazardous consumer material ever produced.2
Low Density Polyethelene (LDPE)
Tough, flexible, transparent, oil resistant, good for heat sealing
Bags for dry cleaning, bread, frozen food, and fresh produce; container lids; toys; squeezable bottles; coating for milk cartons and beverage cups Relatively safe for consumer use, but difficult to recycle.2
Polypropelene (PP)
Resistant to acids, alkalis and most solvents, strong, high melting point, clear
Yogurt containers, take-out containers, medicine bottles, caps and closures; large molded parts for cars and durable appliances Relatively safe for consumer use. PP containers are unlikely to leach toxins into contents even if the containers are hot, exposed to sun, or old.9 Even so, trace amounts of Bisphenol A (BPA) have been found to have leached from PP containers when microwaved.2
Polystyrene (PS)
Can be rigid or foamed (Expanded Polystyrene (EPS) or Styrofoam); clear, hard, brittle; low melting point; strong moisture barrier; low thermal conductivity; combined with rubber for High Impact Polystyrene (HIPS)
Food service items like cups, plates, cutlery, clamshells; protective foam packaging, packing peanuts, compact disc cases and aspirin bottles; agricultural trays, electronic housing, building insulation, coat hangers, medical products, toys Try to avoid! Expanded polystyrene (Styrofoam) poses extreme disposal problems, and it frequently escapes as litter into the environment,10, 11 where wind, sun, and wave action degrade it into known and suspected carcinogens, including styrene monomer (SM), styrene dimer (SD) and styrene trimer (ST).4
Made from a resin other than the six listed above, or from more than one resin in a multi-layer combination
Three-gallon and five-gallon reusable water bottles, bottles for citrus juice and catsup; oven-baking bags, custom packaging Try to avoid, unless it’s bio-based PLA plastic! This category contains a wide variety of plastics, some being relatively harmless, and some containing the hormone disruptors Bisphenol A (BPA), phthalates, and various potential carcinogens.6


Written by

World Centric


Read time

5 minutes


Published on

May 15, 2020


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