Toxins are substances that harm the metabolism of living organisms.
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. 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, and when the organism falls as prey to a predator, the toxin concentrates more intensely in the body of the predator.
Specific chemicals of concern
Toxic substances are used to make nearly all types of plastic. Although different plastic resin types vary widely in their concentrations of toxic chemicals, the plastics industry as a whole releases toxins into the environment during every stage of plastic: production, use, and disposal. Often these toxins are released during the manufacturing process and harm workers and communities living near plastics manufacturing plants, and affect local air and water quality.
Key examples of toxins associated with plastic resins include:
- Antimony (PET #1): a toxic metalloid that can leach into food and beverages, causing vomiting, diarrhea, and stomach ulcers (Source)
- Benzene (PET #1, PVC #3, LDPE #4, PP #5): known human carcinogen, workplace exposure depresses the nervous system (Source)
- Dioxins and other chlorine-based chemicals (PVC #3, PS #6): 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 (Source)
- Lead (PVC #3): damaging to the cardiovascular system, digestive system, renal system (urinary tract and kidneys), blood formation, eyes, and the development of fetuses and children (Source)
- Phthalates (PET #1, PVC #3): linked with asthma, allergies, cognitive and behavioral problems, and reproductive issues (Source)
- Styrene (PS #6): strongly suspected to be a human carcinogen; damaging to the nervous system, liver, and eyes (Source)
Polyvinyl chloride plastic (PVC or vinyl) is especially dangerous because it releases scores of different chlorine-based chemicals and dioxins during its production, all regulated as hazardous air pollutants under the Clean Air Act (Source). Dioxins are internationally recognized as a persistent environmental pollutant and highly toxic. Prolonged exposure to vinyl chloride gas in the workplace can damage the liver, immune system, and nervous systems, and dioxins are also linked to severe health problems like cancer, immune system damage, and hormone disruption (Source).
Toxins leach into food and water
For consumers using products made from plastic, the most common concern is that chemicals can seep into foods and beverages during storage and heating. While individual food packaging may contain minute quantities of chemicals, the risks are magnified with a lifetime's exposure to the chemicals through eating food previously wrapped or stored in plastics.
Among the more well-studied packaging is polystyrene (PS #6) food containers, which have been found to leach the toxin styrene into warm food or drink, posing health risks to the gastrointestinal tract and kidneys (Source). Bisphenol A (BPA) and phthalates, common chemicals in drinking bottles and food containers, are also known endocrine disruptors that interfere with the reproductive system (Source).
When plastics degrade in landfills or as litter, they continue to leach countless chemicals into our soils, streams, rivers, and oceans. The toxins in plastics, such as phthalates, have been found in leachate from landfills (Source), and BPA in plastic marine litter was also found to leach into the environment (Source). Based on studies, printed PE (#4) and PVC (#3) had the highest leaching ratios whereas PET (#1) had the lowest leaching potential.