If you’re like most people, you’ve got a drawer full of Ziploc bags somewhere in your kitchen. They’re basically a staple at this point. But a recent lawsuit is making waves, claiming that using these bags in your freezer or microwave might expose you to something pretty alarming: microplastics. And honestly, the science behind it is worth paying attention to.
What’s going on with the lawsuit
A class action lawsuit was filed in April 2025 against S.C. Johnson & Son, the company that owns Ziploc. The complaint argues that their bags release microplastics when they’re frozen or microwaved. And that’s a problem because the packaging says they’re safe for those uses. California resident Linda Cheslow filed the suit, claiming the marketing is misleading since scientific evidence shows these plastics break down under extreme temperatures. I mean, if you’re labeling something as microwave-safe, it shouldn’t be leaching tiny plastic particles into your food, right?
SC Johnson responded by saying their products are totally safe when used as directed. They also pointed out that microplastics are already everywhere—in our water, our air, the food we eat. But that doesn’t really address whether their bags are adding to the problem.
The materials in question
Ziploc bags are made from low-density polyethylene and polypropylene. These plastics are supposedly more durable than what you’d find in cheaper resealable bags. But the lawsuit cites research showing that both materials can degrade when exposed to the kind of heat you get in a microwave or the cold of a freezer. After trying to dig into this myself, it’s pretty clear that the science isn’t entirely settled, but there’s enough evidence to raise concerns.
A 2023 study published in Environmental Science and Technology found that microwave heating released the highest amount of microplastics compared to other methods. Some containers released over 4 million microplastic particles from just one square centimeter of plastic after three minutes in the microwave. That’s a lot of plastic ending up in your food.
Why freezing might be just as bad
You’d think freezing would be safer since it’s cold, not hot. But the belief is that freezing makes plastic more brittle. And when plastic gets brittle, it sheds more particles. Carmen Marsit, who’s a professor at Emory University, explained that the freezing process can cause more shedding of microplastics into whatever food you’re storing. So basically, you’re not avoiding the problem by using the freezer instead of the microwave. The last time I stored soup in a Ziploc bag in the freezer, I didn’t think twice about it. Now I’m sort of rethinking that habit.
And it’s not just about one-time exposure. It’s the cumulative effect that matters. If you’re using these bags regularly for freezing or reheating, those microplastics add up over time.
What even are microplastics
Microplastics are tiny pieces of plastic that measure less than 5 millimeters long. They come from larger plastics breaking down, but some are intentionally made—like those little beads in hand sanitizer or exfoliating scrubs. Once they’re created, they end up in waterways, oceans, and eventually in the fish and other animals we eat. It’s kind of a vicious cycle. We create plastic, it breaks down, it enters the food chain, and then we consume it again.
Does anyone actually know how much plastic we’re eating? A 2019 study estimated that Americans consume between 39,000 and 52,000 microplastic particles annually just from food. When you add in inhalation and drinking water from plastic bottles, that number jumps to somewhere between 74,000 and 121,000 particles. And the researchers said those numbers are probably underestimates.
Health risks you should know about
The research into how microplastics affect human health is still ongoing, but what we know so far isn’t great. Studies have linked microplastics to digestive problems, respiratory issues, and disruptions to the immune and reproductive systems. A 2023 study in the Yonsei Medical Journal explained that these particles can carry contaminants—chemicals that have been linked to cancer and birth defects. Honestly, that’s pretty alarming when you think about it.
But there’s more. Chemicals in plastic food packaging, like ortho-phthalates and PFAS, can mess with your endocrine system. That’s the system that regulates your hormones, which control everything from your appetite to your metabolism to how your cells grow. A 2024 study even suggested a link between microplastics and colon and lung cancer, though more research is needed to confirm a direct cause. Still, the evidence is piling up.
What Ziploc says about safety
On their website, Ziploc states that their bags can be used in the microwave, but only to defrost or reheat food. They also recommend leaving the zipper open at least one inch to let steam escape. But there’s no mention of microplastics or any potential risk from using the bags this way. The company insists their products are safe when used as directed, and they’ve called the lawsuit meritless. But is that enough?
Some experts aren’t convinced. Brad Younggren from Circulate Health told CNET that repeated exposure to extreme temperatures stresses plastic materials, which can lead to the breakdown of surface layers and the release of tiny particles. Every time I’ve microwaved leftovers in a plastic container, I didn’t think about this. Now it seems like something worth considering.
Are there better alternatives
If you’re worried about microplastics, there are other options. Glass containers are a solid choice for storing and reheating food. They don’t leach particles, and they’re pretty durable. Metal containers work too, though you obviously can’t microwave those. For bags, wax paper bags are an alternative, though they’re not as convenient for everything. I’ve noticed glass containers are more expensive upfront, but they last way longer than plastic. At least that’s been my experience.
And if you do keep using plastic, try to avoid heating it. Room temperature storage is safer than microwaving or freezing. It’s not a perfect solution, but it’s something.
What experts recommend
Most toxicologists agree that minimizing plastic use is a smart move. Dr. Kelly Johnson-Arbor from MedStar Health says it’s nearly impossible to avoid microplastics entirely, but reducing single-use plastics can help. She also suggests avoiding reheating food in plastic containers whenever possible. Jamie Alan, a toxicology professor at Michigan State University, echoed that, saying it’s the cumulative exposure that’ll determine the long-term impact. Basically, the less plastic you use, the better off you’ll probably be.
But let’s be realistic. Completely eliminating plastic from your life isn’t exactly practical for most people. It’s about making small changes where you can and being aware of the risks. After reading all this, I’m definitely rethinking how I use plastic bags. Are they convenient? Absolutely. But are they worth the potential health risks? That’s the question everyone has to answer for themselves.
What happens next
The lawsuit against Ziploc is still ongoing, so we’ll have to wait and see how it plays out. It’ll be interesting to see if the courts find that the company misled consumers or if the science isn’t strong enough to prove harm. Either way, the attention on microplastics isn’t going anywhere. More studies are being published all the time, and public awareness is growing. Maybe that’ll push companies to be more transparent about what’s in their products and how they should—or shouldn’t—be used. Until then, it’s probably safest to err on the side of caution and limit how much you’re microwaving or freezing plastic. Your future self might thank you for it.
