“Pollution” describes materials and substances that are released into the air, water, or soil, and that disrupt the health of ecosystems. These disruptions can occur as physical obstructions, such as when the natural flow of streams are blocked by garbage pile-ups or when animals eat bits of plastic and choke on them, or as chemical obstructions, such as when pollution carries toxins into the environment. “Toxins” describe substances that harm the metabolism of living organisms when those organisms absorb them. Whether or not a substance is toxic depends on its concentration in the organism and the species of the organism, meaning that most determinations of toxicity are open to debate. Nevertheless, many chemicals associated with conventional plastics are indisputably toxic to many species, and their concentrations in the environment are increasing.
Plastic is an extremely common component in pollution today, demonstrated by the sad fact that 80% of ocean debris is plastic.1 No matter how high or how low its level of toxicity, all pollution causes harm and distress to natural systems and living creatures.
Plastic Pollution – Litter
Because it is relatively cheap to manufacture, plastic is produced in staggering volumes and then is frequently discarded as litter. Plastic bags, for example, are used at a rate of about a hundred billion per year in the US alone.2 A study conducted in 2009 by Keep America Beautiful found that, while overall littering in the United States had decreased by 61% from 1969 to 2009, plastic litter had actually increased by 165% during the same period. The study attributed this finding to the skyrocketingamount of plastic packaging used by manufacturers, up 340% per capita over 40 years.3
Plastic litter can be deadly to wildlife in many ways. Plastic bags and plastic food containers often carry scents that appeal to animals, attracting them to eat the plastic. Over a hundred thousand animals – ranging from sea turtles to albatrosses to camels – die each year from the ingestion of plastic bags.2, 4 The plastic becomes permanently lodged in the animals’ digestive tracts, blocking the passage of food and leading to death by starvation or infection. Animals also frequently die from entanglement in plastic fishing lines and plastic six-pack holders, and sometimes by getting trapped inside plastic bottles and containers. Plastic litter frequently piles up along the shores of lakes, disrupting the nesting patterns of waterfowl.5
Improper disposal of plastic is a major contributor to water pollution. Styrofoam cups, plastic bags, caps from ballpoint pens – an endless stream of plastic litter is swept down urban storm drains into streams, rivers, and ultimately into the ocean. Marine animals are especially prone to eating minute bits of plastic, because they look similar to their natural prey or because they are contaminated with food residue.6 Again, ingested plastic can block an animal’s digestive tract, causing starvation, infection, and death.
Even in the emerging green industry of commercial composting, plastic litter is a major challenge. The organic refuse that is collected from homes and small businesses typically arrives at commercial facilities bearing a variety of plastic contaminants such as plastic bags, plastic-coated paper products (like milk cartons), and diapers. Most composters use a ½ inch (12 mm) sieve to screen contaminants from their finished compost.7 However, smaller pieces will bypass the sieve and contaminate the finished compost. At this point, the concern shifts from a question of physical obstruction to a question of toxicity. The long-term chemical inertness of different plastic resins in soil has not been studied sufficiently. Some types of plastic are known to leach toxins into foods and beverages when heated.8 It remains to be determined whether any types of plastic also leach toxins into soil.
Plastic Pollution – Toxins
From start to finish, plastics release toxins into the environment. Granted, different plastic resin types vary widely in their levels of chemical inertness and concentrations of toxic chemicals. Even so, as a whole, the plastics industry releases toxins into the environment during every stage of plastic: during its production, its use, and its disposal.
All organisms are threatened by the toxic chemical byproducts of plastics, especially humans and other predator species. All animals absorb these chemicals through ingestion and inhalation. If an organism cannot break down or excrete a toxin, that toxin will build up in the organism. Over time, the toxin will become more concentrated in the organism than it is in the surrounding environment. When the organism falls as prey to a predator, the toxin concentrates even more intensely in the body of the predator.9 Dioxin and other chorine-based toxins are already so concentrated in the food chain that all creatures on Earth appear to carry measurable levels in their bodies.8 As early as the 1980’s, the U.S. Environmental Protection Agency demonstrated that styrene – the molecular building block of all polystyrene, including Styrofoam – was present in 100% of the samples of human fat that they collected from all 48 states in the continental United States.10 Toxins such as dioxin, chloride, styrene, PCB, BPA, and many others lead to deadly conditions like cancer, immune system damage, and hormone disruption in humans and other animals.11, 12
Toxins in the production of plastic: Toxic substances are used to make nearly all types of plastic. Some of these toxins escape from the manufacturing process and damage workers in the plastics industry, communities living near plastics manufacturing plants, and the global environment as a whole. Key examples of toxins used in the production of plastic resins include:13
- Polyethylene Terephthalate (PET, #1): antimony oxide, diaszomethane, lead oxide, nickel.ethylene oxide, and benzene
- High Density Polyethylene (HDPE, #2): chromium oxide, benzoyl peroxide, hexane, and cyclohexane
- Polyvinyl Chloride (PVC, #3): benzene, carbon tetrachloride, 1,2-dichloroethane, several phthalates, ethylene oxide, lead chromate, methyl acrylate, methanol, phthalic anhydride, tetrahydrofuran, and tribasic lead sulfate
- Low Density Polyethylene (LDPE, #4): benzene, chromium oxide, cumene hydroperoxide, and tert-butyl hydroperoxide
- Polypropylene (PP, #5): methanol, 2,6-di-tert-butyl-4-methyl phenol, and nickel dibutyl dithiocarbamate
- Polystyrene (PS, #6): styrene, ethylbenzene, benzene, ethylene, carbon tetrachloride, polyvinyl alcohol, antimony oxide, and tert-butyl hydroperoxide, bensoquinone
The Centers for Disease Control designate many of these toxic substances as known human carcinogens. They also designate particular toxic effects that are uniquely associated with each substance. Some of the most significant toxic effects associated with substances used or emitted in plastic production include:13
- Benzene (PET, PVC, LDPE, PP): known human carcinogen, workplace exposure depresses the nervous system
- Chromium oxide (HDPE, LDPE): suspected carcinogen, damaging to the liver and nervous system
- Dioxins and other chlorine-based chemicals (PVC, PS): known human carcinogens, damaging to the immune system, hormonal system, and fetal development; prolonged exposure to chlorine-based gases in the workplace can damage the eyes, skin, respiratory system, and nervous system
- Ethylene oxide (PET, PVC): known human carcinogen, damaging to the nervous system, renal system (urinary tract and kidneys), skin, and eyes.
- Lead (PET, PVC): damaging to the cardio-vascular system, digestive system, renal system (urinary tract and kidneys), blood formation, eyes, and the development of fetuses and children
- Nickel (PET, PP): suspected human carcinogen, damaging to the cardiovascular system, nervous system, respiratory system, and skin
- Phthalates (PET, PVC): damaging to the hormonal system
- Styrene (PS): strongly suspected to be a human carcinogen; damaging to the nervous system, liver, and eyes.
Polyvinyl chloride plastic (PVC or “vinyl”) is especially dangerous in terms of toxicity, since it releases scores of different chlorine-based chemicals and dioxins during its production, all regulated as hazardous air pollutants under the Clean Air Act.8, 14 The U.S. Environmental Protection Agency has classified vinyl chloride, the precursor of PVC, as a known human carcinogen.15 Throughout its lifecycle, PVC plastic creates more of the nation's dioxin pollution than any other industrial product.8 Dioxin is internationally recognized as a persistent environmental pollutant and highly toxic.16 Dioxin and other chorine-based toxins are already so concentrated in the food chain that all creatures on Earth carry measurable levels in their bodies, causing severe health problems like cancer, immune system damage, and hormone disruption.8Prolonged exposure to vinyl chloride gas in the workplace can damage the liver, immune system, and nervous system.17 PVC is a strong contender for being the most environmentally hazardous consumer material ever produced.
Toxins in the use of plastic: Consumers also face exposure to toxins from the use of products made from plastic. The most common concern in this regard is that chemicals in plastic containers can seep into foods and beverages during heating.18 Polystyrene (PS) food containers are especially known for leaching the toxin styrene into warm food or drink, posing health risks to the gastrointestinal tract and kidneys.10Bisphenol A (BPA) and phthalates are other problematic chemicals commonly used in making plastic food containers and drinking bottles from PET, HDPE, and PP plastics. BPA and phthalates are known endocrine disruptors that interfere with the hormone system, and safe levels of exposure have not yet been established.19
Toxins in the disposal of plastic: When incinerated, plastics release over 90 different chemicals into the atmosphere. When plastics are thrown away as litter or escape from landfills on wind and water, they leach countless chemicals into our soils, streams, rivers, and oceans.
Because so many different types of plastic are burned and degrade every day (PVC, PS, PP, HDPE, LDPE, etc.), and because they release so many different toxic chemicals into our environment (PCB, BPA, dioxin, chloride, styrene, etc.), it is impossible to quantify the level of toxicity that plastics pose to life on earth. Government studies indicate it is likely that every person’s body in the U.S carries styrene10 and every animal’s body on the planet carries dioxin.8 For every known biological system – including the nervous system, reproductive system, immune system, hormonal system, and the regulation of cell reproduction and cancer – research has found a variety of plastic’s component substances to be toxic.