A lawsuit alleges that Ziploc bags shed microplastics when microwaved or frozen. Bob Chamberlin / Los Angeles Times
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A new lawsuit is questioning the “microwave safe” and “freezer safe” claims of Ziploc plastic bags. The lawsuit against S.C. Johnson alleged that these claims for its Ziploc brand products are misleading, and that these uses of the products increase risk of exposure to microplastics.
According to the lawsuit documents“Defendant affirmatively markets its Ziploc bags and containers (the ‘Products’) as ‘Microwave Safe’ and suitable for ‘Freezer’ use, creating the reasonable impression that they are fit for use in the microwave and freezer. In reality, these Products are made from polyethylene and polypropylene — materials that scientific and medical evidence shows release microplastics when microwaved and frozen — making them fundamentally unfit for microwave and freezer use. Relying on Defendant’s false misrepresentations, individuals have unwittingly exposed themselves and their families to undisclosed microplastics during routine kitchen practices.”
As CNET reported, exposing polyethylene and polypropylene to extreme temperatures, such as heat from a microwave or the cold of a freezer, causes the surface of these materials to begin breaking down and shedding microscopic pieces.
But the lawsuit alleges that Ziploc has not addressed this occurrence on its packaging, yet labels its products safe to use in microwaves or freezers.
According to a 2024 studythere are other concerns over microplastic shedding from these types of self-closing “zippered” plastic bags. According to that study, which analyzed Armada, Hercules and Ziploc branded bags, but is not involved or cited in the lawsuit, these bags can release microplastics and nanoplastics every time they are opened and closed. These findings could raise additional concerns over claims that these bags are safely reusable, an argument that was also made in the lawsuit.
“Given that Defendant markets the Products as reusable, it is foreseeable that the Products may undergo multiple freeze-thaw and reheat cycles,” the lawsuit said.
Ziploc is not the only company facing lawsuits over alleged microplastic risks. As CNET reported, Newell Brands is being sued, with the plaintiffs claiming that certain Rubbermaid containers marketed as “microwave safe,” “microwave reheatable” and “freezer safe” could also be shedding microplastics in food. The lawsuit alleged that the products, made from polypropylene plastic, shed microplastics when microwaved or frozen.
“By promoting the Products as affirmatively safe while concealing these material risks, Defendant has duped consumers nationwide out of millions of dollars, placing their health and welfare in jeopardy. Sadly, this also includes millions of families specifically targeted for purportedly safe on-the-go school and work meals, and vulnerable children for whom ingesting microplastics is especially dangerous,” the lawsuit stated.
Microplastics are everywhere, but currently, the U.S. Food and Drug Administration has stated that there are no known risks to human health by microplastics detected in food. However, more studies are investigating potential human and environmental health risks posed by these particles.
A study published earlier this year found that microplastics were accumulating in mice brains, causing blood flow blockages. A separate study found microplastic accumulation occurring in human brains. Yet another study published in January linked the presence of microplastics in human placentas to premature birthswhile another early 2025 study linked microplastic exposure to several respiratory, digestive and reproductive risks.
The FDA has said that if the agency confirms safety risks from microplastics or nanoplastics present in food, it will establish regulations in response.
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