By Keanu Heydari, Environmental Storyteller Fellow, Rackham Graduate School
On an ordinary morning, it feels reasonable to trust the symbols and labels on the things we buy. A parent pulls a bottle of sparkling water that proudly advertises “100% recycled plastic” from the fridge. A child drags a stuffed animal across the floor on the way out the door, its tag listing polyester as the main material. The bottle carries the familiar #1 recycling triangle that signals PET plastic and suggests something safe and responsible. The toy is made from the same PET, even though it has no recycling symbol and will never go in a curbside recycling bin.
A new peer-reviewed study co-led by the Ecology Center shows that this story is incomplete.
The study compared virgin and recycled PET and asked two basic questions: Which chemicals are present in these materials, and do those mixtures interfere with hormone receptors in laboratory tests? It found that PET beverage bottles, polyester clothing, and children’s toys commonly sold in the United States can release complex mixtures of hazardous chemicals into water under conditions that mimic everyday use. The results also show that both manufacturing and recycling of PET generate more than a dozen hazardous byproducts that were not intentionally added to the plastic.
Gillian Miller, senior scientist at the Ecology Center, described her reaction in stark terms: “I was struck by how many chemicals with known toxicity leached out of the bottles and polyester clothing and toys into just water. The amounts aren’t high enough to cause immediate health effects; instead the concern is exposure over the long term and release into waterways at points during the whole life of the plastic or textile.” Her comment underlines two points that run through the study: These are everyday products, and the exposures they create are cumulative (i.e. worse over time).
This article explains what the Ecology Center study found, why it matters for Michigan communities, and how a related Italian study supports the call for stronger protections.
PET In Everyday Life
Polyethylene terephthalate, usually called PET or PETE, appears almost everywhere. It is the clear plastic used for many disposable beverage bottles. It is the fiber that makes up much of the polyester clothing in closets and drawers. It is the stuffing inside countless pillows and plush toys that children keep close at night.
PET begins its life as fossil fuel. Oil and gas are refined into chemical feedstocks, which are transformed into pellets of plastic resin. Manufacturers melt and shape those pellets into bottles and fibers. At several stages, they blend in other compounds that help the material flow more easily, resist heat, stay clear, or meet flammability standards. None of this complexity is visible to the shopper who picks up a bottle or reaches for a fleece sweatshirt. In most cases, there is no requirement to disclose the additives or the by-products that end up in the finished product.
If PET is not a single, inert substance but a mixture of the base polymer plus additives and non-intentionally added substances which are formed during polymer production and recycling, what actually moves out of that material and into water under conditions that resemble real use and real pollution?
The Study
To answer that question, the Ecology Center designed a project around products that families actually use and discard. Staff in our Healthy Stuff Lab led the study design, selected the products, and coordinated work across several partners. Defend Our Health, the Alliance of Mission-Based Recyclers, Toronto Metropolitan University, and Wayne State University contributed scientific expertise, laboratory testing, and policy framing.
The team purchased PET beverage bottles containing water and soda from stores in Michigan and California. They also bought children’s textiles, including plush toys, pillows, and clothing, from shops and online retailers in Michigan and Oregon. For each category, they selected pairs of products: one made from virgin PET and a counterpart marketed as containing recycled PET. This design allowed the researchers to compare chemical patterns in new and recycled material rather than treating “PET” as a single undifferentiated category.
The study then followed two main paths. First, Toronto Metropolitan University researchers carried out leaching experiments using filtered lake water. Cut-up pieces of the bottles and textile products were submerged in it under controlled conditions that mimic temperature and light exposure in real lakes. After a defined period, the team analyzed the water to see which compounds had moved out of the plastic. Second, they performed solvent extractions of the bottles and textiles to draw out a broader range of substances. These extracts were analyzed for known PET additives and a variety of volatile organic compounds that have been detected by other researchers in PET. Extracts were also tested in cell-based assays that measure interference with hormone receptors.
As Ecology Center Executive Director Mike Garfield notes, the project was demanding and unusual. It required close coordination between university laboratories, a commercial laboratory, and several nongovernmental organizations that approached the problem from different vantage points. It is also the first study of its kind that relies on PET bottles and textiles purchased in the United States, under U.S. regulatory rules, rather than on samples from Europe or Asia. That distinction matters because chemical rules and manufacturing practices differ from region to region. Without data from U.S. products, claims of safety rest on incomplete evidence.
What The Researchers Found In PET Bottles And Textiles
The findings call into question the idea that PET is a simple, stable material, and highlight that PET contains hazards in line with other plastics. Across the bottles and textiles, the team identified a wide range of substances of concern. These included plastic additives designed to be present from the start, such as certain flame retardants and processing aids, and compounds that appear to result from breakdown reactions (Non Intentionally Added Substances or NIAS’s) or contamination during manufacturing and recycling, like adhesive chemicals from labels.
The study reports twelve additives that fall into a category known as persistent, mobile, and toxic (PMTs). Chemicals in this group tend to travel easily through water and can be difficult to remove once they reach rivers and drinking water sources. The researchers also detected six organophosphate esters, which can serve as flame retardants or lubricants, and fifteen non-intentionally added substances, including solvents, monomer residues, and breakdown products. Ethylene glycol, diethylene glycol, 2-methyl-1,3-dioxolane, benzaldehyde, and several other aromatic compounds appear repeatedly in the data.
Crucially, many of these substances were detected not only in solvent extracts but also in lake water that comes into contact with PET products. That means the chemicals are leaching under conditions that resemble environmental exposure. They are not locked away permanently in the plastic matrix. When bottles sit full of liquid or when polyester textiles are washed and shed fibers, compounds from inside the material can enter the water that people drink and the watersheds that communities depend on.
The study also challenges easy assumptions about the superiority of one kind of PET over another. Virgin PET and recycled PET do not share identical chemical profiles. They differ in ways that are important for policy, yet neither comes out as entirely reassuring.
Virgin PET bottles in the study tend to contain higher levels of ethylene glycol and 2-methyl-1,3-dioxolane, compounds associated with the production of fresh PET resin. Recycled PET bottles, by contrast, contain benzene far more often. Benzene is a known human carcinogen. In this data set, it appears consistently in recycled PET bottles and only once in a bottle made from virgin PET. Organophosphate esters also turn up more frequently in recycled PET. The researchers point to contamination from other plastics, particularly PVC, as a likely source. When PVC or other incompatible materials slip into PET recycling streams and are processed at high temperatures, they can generate benzene and other hazardous by-products that then travel forward into new bottles made from rPET.
The differences between bottles and textiles are also revealing. Beverage bottles commonly contain ethylene glycol, diethylene glycol, limonene from flavorings, and antimony, which is used as a catalyst in PET resin. Textiles and plush toys more often contain formaldehyde, toluene, styrene, and specific glycols and flame retardants. These patterns reflect different manufacturing processes and different performance goals, yet they share a common thread. In both categories, mixtures of hazardous substances are present and capable of moving into water.
For children, that pattern has clear implications. Young children sleep with stuffed animals, wear polyester pajamas, and chew on zippers, seams, and blanket corners. They also drink from PET bottles that adults assume are safe. The exposures are low level but persistent and layered onto other environmental burdens that families may face.
Signals Of Hormone Disruption
The chemical analyses tell one part of the story. Experiments on biological activity tell another. When the research team at Wayne State applied extracts from PET bottles and textiles to living cells, they saw consistent evidence of interference with hormone receptors in the cells.
The mixtures drawn from PET products affected receptors for estrogens, androgens, thyroid, and other hormones in the cells. These effects appeared in extracts from virgin and recycled PET and in samples taken from both bottles and textiles. The patterns varied in strength, but there was no clear case that any one subset of PET products could be treated as hormonally benign.
It is important to acknowledge what these bioassays do and do not show. They are in vitro tests, not clinical studies of disease. They cannot demonstrate that a particular bottle will cause a particular health outcome in a particular person. They do, however, show that the real mixtures of substances leaching from PET can interfere with hormone activity at levels detectable in the laboratory.
Endocrine-disrupting chemicals are well known to have effects at very low doses, especially during pregnancy and early childhood, when hormonal signals help to guide organ formation, brain development, and metabolic programming. A cautious reading of the Ecology Center study therefore sees these bioassay results as an early-warning signal rather than a negligible curiosity. When materials that touch food, skin, and children’s mouths carry mixtures that block hormone receptors in vitro, it is reasonable to ask why the regulatory system treats these plastics as inherently safe.
Why This Matters For Michigan People And Waters
The Ecology Center team used filtered lake water in its leaching experiments for a reason. PET waste does not vanish when it leaves the curb. Fibers and fragments enter storm drains and rivers. Washing machines send polyester microfibers, along with attached chemicals, to wastewater plants, which are not designed to capture every small particle or every dissolved compound. From there, contaminants can reach surface waters, including the Great Lakes.
The category of persistent, mobile, and toxic additives is especially troubling in this context. Chemicals that dissolve readily in water and travel long distances are difficult to control once they leave the product. Water utilities can filter out some contaminants, but not all. Communities that already live with aging infrastructure and limited resources face the greatest challenges in addressing new waves of pollution.
The burden of PET production and disposal also falls unevenly. Defend Our Health’s “Hidden Hazards” research maps PET resin plants and the chemical facilities that supply them and shows that many are clustered in the Gulf Coast and southeastern United States in communities where residents are more likely to be people of color and have lower incomes than the national average. These plants release hazardous pollutants such as ethylene oxide and 1,4-dioxane to air and water, and mechanical recycling of PET bottles can generate benzene and styrene that migrate into new products. Workers inside these facilities and neighbors downwind or downstream face cumulative exposures from multiple industrial sources. The Ecology Center reads the PET findings through this lens of environmental justice: a plastic system that markets convenience to some households concentrates health risks and cleanup costs on others.
For a state defined by fresh water, these questions are not abstract. The same lakes that draw visitors and anchor local economies can serve as sinks for plastic fibers and chemically loaded additives. The longer petrochemical plastics dominate packaging, clothing, and toys, the more difficult it becomes to separate commerce from contamination.
How A Related Italian Study Fits In
The Emerging Investigator article led by the Ecology Center stands at the center of this discussion. It draws on U.S. products, connects chemical profiles to endocrine activity, and frames the findings in terms of environmental and human health. At the same time, it does not exist in isolation. Other researchers are beginning to see similar patterns.
A recent study from Italy by Di Duca and colleagues examined recycled PET flakes, granules, and preforms used for food packaging. The Italian team found that recycled PET samples contained higher concentrations of volatile organic compounds and phthalate esters than virgin PET. They also observed that contamination tended to increase as material moved through the recycling process toward bottle preforms. Ethylene glycol, 2-methyl-1,3-dioxolane, benzaldehyde, benzene, and several phthalates appeared frequently in their data.
The details of the Italian work differ from the Ecology Center project, but the broad message is consistent: mechanical recycling systems that rely on mixed plastic streams tend to carry non-intentionally added substances forward, and in some cases they may amplify those contaminants rather than reduce them. Without effective decontamination and strict control of input materials, recycled PET is likely to contain new chemical hazards beyond what is present in the original plastic.
Together, the two studies point to a structural problem rather than an isolated glitch: a recycling policy that celebrates recycled content in PET bottles without confronting the virgin plastics’ inherent chemical hazards is also creating a contamination problem within the global plastic waste issue.
Rethinking PET, Recycling, And Responsibility
The Ecology Center does not argue that recycling should stop. The study instead questions a narrow vision of sustainability that treats recycled content as a sufficient badge of virtue. If recycled PET carries benzene and other hazardous contaminants more often than virgin PET, and if both forms carry mixtures that interfere with hormone receptors in vitro, then the label “100% recycled” deserves more scrutiny than it currently receives.
Finally, both studies show the unavoidable presence of PET production degradation products (NIASs) in both virgin PET and rPET. This illustrates that PET, similar to other plastics, has inherent hazards. This commonality of the hazards calls for broader regulatory approaches that address these complex chemical mixtures and reduce production of petrochemical plastics in the first place.
Gillian Miller puts the larger picture bluntly. “There are many good reasons to stop using so much petrochemical plastic for packaging, clothing, and toys. From fracking chemicals getting into water supplies to wildlife bellies full of plastic to the leachable chemicals our new study found, it is all just making profits for a few large corporations while leaving a global mess.” Her comment threads together extraction, wildlife harm, and chemical leaching in a way that raises a basic question: who benefits from this system, and who lives with its consequences?
For policymakers, the study points toward several directions. Policy makers should enact protections that address the problems of mixtures, non-intentionally added substances, and endocrine activity in PET and other plastics. Rules that encourage recycled content should be paired with strict limits on contaminants, including an outright ban on PVC and other incompatible plastics that feed benzene formation. For companies that make beverages and children’s products, sustainability claims should rest on genuine chemical safety, not only on the presence of recycled resin.
For Michigan residents and Ecology Center members, the study offers both cause for concern and grounds for action. Households can reduce reliance on bottled water where safe tap water and good filters are available, shift toward glass or stainless-steel containers, and pay attention to how often synthetic clothing goes into the wash. These steps cannot replace systemic reform, but they can lower individual exposure and signal demand for safer options.
More importantly, members can help turn this science into policy. That can mean contacting legislators, speaking with school boards and child-care providers about purchasing policies, supporting bottle bills and reuse programs, and backing campaigns that push for safer materials and stronger chemical protections. It can also mean supporting the Ecology Center’s own work, which depends on member contributions to fund independent testing, policy analysis, and coalition building.
The study’s message is clear. Our bottles, clothes, and toys can carry hidden chemical burdens that move into our water, our bodies, and our ecosystems. Changing that reality will require pressure on regulators and elected officials, and it will require a shift in how we think about plastic in the first place.
Sources Cited
- Li, Y., Fries, E., Miller, G. Z., Gearhart, J., McGrail, D., Kassotis, C. D., and Sühring, R. “Emerging investigator series: Unpacking PET: comparative analysis of leachable and extractable contaminants from virgin and recycled polyethylene terephthalate bottles and textiles.” Environmental Science: Processes & Impacts (2025). DOI: 10.1039/D5EM00615E.
- Ecology Center. “Unpacking PET: Comparative Analysis of Leachable and Extractable Contaminants From Virgin and Recycled Polyethylene Terephthalate Bottles and Textiles.” Member-facing summary, 23 October 2025.
- Di Duca, F., Montuori, P., De Rosa, E., and collaborators. “Occurrence of volatile organic compounds (VOCs) and phthalate acid esters (PAEs) in recycled PET: implications for food packaging materials.” Journal of Chromatography A 1763 (2025): 466433. DOI: 10.1016/j.chroma.2025.466433.
- Defend Our Health. “Problem Plastic: How PET Beverage Bottles Threaten Health.” Report and executive summary, 2022.
- Defend Our Health and Beyond Petrochemicals. “Hidden Hazards: The Chemical Footprint of a Plastic Bottle.” Report, May 2023.