Our critique explores the limitations of plastic recycling and the health hazards of plastic exposure. It delves into the challenges of recycling, including low recycling rates, contamination, and the deceptive practice of mass balancing.
by Stuart M. Caplen, MD updated 9/26/24
Worldwide production of plastic, according to the United Nations Environmental Program, is about 430 million metric tons per year.[1] This compares to 2 million metric tons of plastic produced in 1950.[2]
About 9% of these plastics are recycled, 12% incinerated, and 79% deposited in landfills or disposed of into the natural environment in places such as rivers, seas or oceans.[3]
Some of the sources of environmental plastic may not be obvious. It is estimated that plastic from tire wear is responsible for about 8.6% of the plastic content in the oceans.[4] Each year, laundering clothing made of artificial fibers is estimated to release 500,000 metric tons of plastic microfibers (the equivalent weight of about 3 billion polyester shirts) which end up deposited into the waterways and oceans.[1,5] However, by far, the largest amount of plastic deposition comes from plastic waste.[1] It is estimated that by the year 2050 there may be more plastic by weight in the ocean than fish.[6]
99% of plastics are made from fossil fuels.[2] There are several potential health issues which may be caused by exposure to plastics. Chemicals in plastic can leach out which represents a problem with food packaged in plastic or processed with plastic tubing. Aluminum beverage cans and aluminum dishes may have a plastic coating, as may cardboard containers. Some of the compounds in plastics have been linked to a number of serious health issues.[7]
In addition to chemicals leaching from plastics, another potentially serious health problem is related to microplastics (extremely small plastic fragments or fibers), which enter the food chain. Microplastics have been found in many food and environmental items such as fish, meat and chicken, fresh fruits and vegetables, tap water, bottled water, rice, sea salt, and honey.[7] Microplastics are now also present in the environment in places such as ocean water, ground water and in the soil.[7] Research on the effects of microplastics on human health is at an early stage, but ingested or inhaled microplastic fragments or fibers have been detected in human brains, hearts, lungs, kidneys, livers, intestines, testes, bone marrow, hip and knee joint synovial membranes, atherosclerotic plaques, and feces.[7] In one study, subjects who had plastic particles in their carotid artery atherosclerotic plaques had a 4.5 times higher risk of having a stroke, myocardial infarction or death in the next 34 months compared to those that did not.[8] With respect to infants, microplastics have been found in breast milk, polypropylene infant feeding bottles, infant feces, and placentas indicating humans now may possibly be exposed to plastic microparticles for their entire lives.[7] More research on harmful effects of plastic exposure and the deposition of microplastics in the body is needed.
Given that modern societies are using vast amounts of plastics which can leach potentially toxic chemicals into food and the environment, as well as produce microparticles that can be absorbed into bodily organs, can we recycle our way out of this plastic dilemma?
Recycling holds the promise of decreasing the one-use plastic culture, but recycling has a number of problematic issues. It is currently more expensive to recycle plastic than to use virgin plastic in products.[9,10] Different types of plastics cannot be mixed when recycling so they need to be sorted, which is a time-consuming process.[10] Another issue with recycled plastics is that new chemicals may be introduced into the plastic when it is recycled. When toxic substances are stored in plastic containers, the plastic can absorb some of them. If that plastic is then recycled, those substances may be incorporated into the new plastic products which may then leach out.[11] Recycled plastics are not generally as structurally sound as virgin plastics[12] and more chemicals appear to leach out of recycled products than virgin plastic.[11] In addition, the environment around plastic recycling plants may become contaminated with plastic components.[11]
Although the worldwide rate of recycling is estimated to be about 9%, in 2021 the estimated recycling rate of plastic products in the U.S. was only 5%-6%.[9] Greenpeace did a survey of 375 plastic recycling facilities in the U.S. in 2022 and found only two types of plastics were accepted by 100% of the facilities, polyethylene terephthalate (recycling code 1), used in items such as water bottles and salad covers and high-density polyethene (recycling code 2), used in plastic milk and detergent bottles. Polypropylene tubs and containers, used for products such as yogurt containers (recycling code 5), were only accepted by 52% of the facilities. After that there was a steep drop-off with items such as plastic cups accepted by 9% of the facilities and plastic bags, plates, and cutlery being accepted by 2% or less of the recycling facilities.[10] In 2022 only an estimated 60% of U.S citizens had access to municipal collection for polyethylene terephthalate and high-density polyethene bottles, and only 29% had access to municipal collection for polypropylene tubs and containers. In that same year the actual capacity of the U.S. to process plastic waste was estimated to be only 21% for polyethylene terephthalate refuse, 10% for high-density polyethene refuse and less than 5% for polypropylene tubs and containers.[10] As a result, most plastic products are either not eligible or not able to be recycled and most of the items intended for recycling end up in landfills, or in some locations, incinerated.[9,10]
In traditional recycling, called mechanical recycling, the plastic is shredded and then melted into pellets to be reused.[11,12] However, a newer process called chemical recycling, or pyrolysis, uses heat, solvents and pressure to break down plastic to molecular components and then recombines them to make different products from the plastics. An advantage of pyrolysis is that it can process types of plastics which are currently not accepted by standard mechanical recycling facilities, such as smaller plastic items and bags, which can jam mechanical shredders.[12] One best-case estimate for the near future, is that given current capabilities in pyrolysis facilities, pyrolysis could only produce 0.2% of new plastic used per year.[13] In the pyrolysis process,15%-20% of plastic waste is recycled as plastic with 80%-85% of the plastic made into other products such as diesel fuel, hydrogen, methane, and other various chemicals. In comparison, 55%-85% of plastic is recycled with mechanical shredding and therefore 15%-45% of the material becomes waste needing disposal.[13]
While it is theoretically possible to assign recycled material percentages to the plastic pellets created in mechanical shredding, it is virtually impossible to know with pyrolysis exactly how much of the recycled materials are in each product. One straightforward approach is to use a proportional method where all of the end products are given a recycled material percentage based on the weight or volume of the material produced. However, that method is not used in pyrolysis, and mass balancing has become the standard method of calculating recycled plastic percentages in products. Mass balancing is based on the principle that the number of molecules of recycled material going in must equal the number of molecules coming out of the process. However, using this method has allowed recyclers to assign recycled plastic percentages to products that may not be true percentages. Reasons for doing this may be that higher percentages of recycled plastic in high-grade plastics may be more profitable because using recycled plastic is now a sign of corporate environmental responsibility, and higher percentages are more desirable.[12,13]
To explain mass balancing, let’s say a recycling facility makes four products recycling a combination of virgin and recycled plastic by pyrolysis; high-quality plastic, low-quality plastic, petroleum-based products and fuel. Enough recycled plastic is added, so that each of the four final products actually contains about 25% recycled materials.
With mass balancing, as long as the final total is 100%, the percentage of recycled plastic can be shifted among products. For example, if the manufacturer decides to label the low-quality plastic, which actually has 25% recycled materials, as having zero recycled materials, that percentage can be shifted over to the high-quality plastic. Mass balancing allows the recycler to claim that the high-quality plastic was made of 50% recycled materials when it actually contained only 25%. Recycled plastic pellets with a minimal amount of recycled plastic can theoretically be sold as having 100% recycled materials as long as all the other products produced in that group were listed as having zero recycled materials.[12,13,14]
According to the New York Times, a recycling company can also build a balance sheet of recycled credits that later can be used on other products. Thus, due to mass balancing and the ability of the recycler to randomly assign recycling percentages to plastic pellets, product manufacturers and consumers may not know how much of the product was actually made from recycled plastic.[12] There are currently no standards for mass balance certification in the U.S.[12]
Given the large amount of plastic being manufactured, the low percentages of plastic actually being recycled, and the inefficiencies and economics of the recycling process, it seems unlikely that recycling will ever be able to solve either the problem of environmental plastic pollution or human exposure to plastic. It is already known that chemicals which can leach out of plastic into foods can potentially cause significant health issues. While research into human microplastic exposure is still emerging, it is clear from the data gathered so far, that humans are both being exposed to and are absorbing some microplastics. It is possible that once more studies are completed, it may be determined that absorbed microplastics are a slow-motion health crisis, which may take decades to manifest in individuals. It does not seem likely that plastic particles, made from petroleum products, which are accumulating in various organs would be beneficial to human health.
It may turn out that the only way to significantly reduce human exposure would be to remove plastic products from both the food chain and food packaging. The question is whether in the future, society would be willing to make the significant changes necessary to accomplish that goal.
If you found this article interesting you may also want to read the article The Effects of Plastics on Human Health .
Author’s note: A thank you to Dr. Theodor Feigelman for editing this article.
References
[1] Everything you need to know about plastic pollution. UN Environment Programme. 25 Apr 2023. https://www.unep.org/news-and-stories/story/everything-you-need-know-about-plastic-pollution
[2] Azoulay D et al. Plastic & Health The hidden Costs of a Plastic Planet. Ciel. February 2019. Retrieved from: https://www.ciel.org/wp-content/uploads/2019/02/Plastic-and-Health-The-Hidden-Costs-of-a-Plastic-Planet-February-2019.pdf
[3] Geyer R et al. Production, use, and fate of all plastics ever made. Sci. Advances .3,e1700782(2017). Retrieved from: https://www.science.org/doi/10.1126/sciadv.1700782
[4] Breaking the Plastic Wave. PEW Charitable Trusts 2020. https://www.systemiq.earth/wp-content/uploads/2020/07/BreakingThePlasticWave_MainReport.pdf
[5] A New Textiles Economy: Redesigning Fashion’s Future, The Ellen McArthur Foundation. 2017. https://emf.thirdlight.com/file/24/uiwtaHvud8YIG_uiSTauTlJH74/A%20New%20Textiles%20Economy%3A%20Redesigning%20fashion%E2%80%99s%20future.pdf
[6] The New Plastics Economy: Rethinking the future of plastics & catalysing action. Ellen McArthur Foundation. 2016. Retrieved from: https://emf.thirdlight.com/file/24/RrpCWLER-yBWPZRrwSoRrB9KM2/The%20New%20Plastics%20Economy%3A%20Rethinking%20the%20future%20of%20plastics%20%26%20catalysing%20action.pdf
[7] Caplen, SM. The Effects of Plastics on Human Health. FibonacciMedicine. Last updated 8/21/24. Retrieved from: https://www.fibonaccimd.com/post/the-effects-of-plastics-on-human-health
[8] Marfella R et al. Microplastics and Nanoplastics in Atheromas and Cardiovascular Events. NEJM. VOL. 390 NO. 10. March 6, 2024. Retrieved from: https://www.nejm.org/doi/full/10.1056/NEJMoa2309822
[9] The Real Truth About the U.S. Plastics Recycling Rate. Beyond Plastics and The Last Beach CleanUp. Bennington College. May 4, 2022. https://static1.squarespace.com/static/5eda91260bbb7e7a4bf528d8/t/62b2238152acae761414d698/1655841666913/The-Real-Truth-about-the-US-Plastic-Recycling-Rate-2021-Facts-and-Figures-_5-4-22.pdf
[10] Circular Claims Fall Flat Again 2022 Update. Greenpeace. October 2022. Retrieved from: . https://www.greenpeace.org/usa/wp-content/uploads/2022/10/GPUS_FinalReport_2022.pdf
[11] Forever Toxic, The Science on Health Threats from Plastic Recycling. Greenpeace. May 2023. Retrieved from: https://www.greenpeace.org/usa/wp-content/uploads/2023/05/GreenpeaceUSA_ForeverToxic_ENG.pdf
[12] Creswell J and TabuchiIs H. Your Water Bottle Really Made From Recycled Plastic? The New York Times. Aug. 26, 2024. Retrieved from: https://www.nytimes.com/2024/08/26/business/energy-environment/tritan-renew-plastic-bottles-recycled.html
[13] Song L. Selling a Mirage. ProPublica. June 20, 2024. Retrieved from: https://www.propublica.org/article/delusion-advanced-chemical-plastic-recycling-pyrolysis
[14] Daphne T, Ahmed N. Mass balance for plastics: Different methods that advance chemical recycling. Circularize. May 22, 2024. Retrieved from: https://www.circularise.com/blogs/mass-balance-for-plastics-different-methods-that-advance-chemical-recycling
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