I assumed that microwaving frozen dinners in the little plastic trays they all come in is bad for you, but am having a remarkably difficult time coming up with a credible cite.
I don’t eat a lot of frozen dinners – maybe twice a month – but enough to get me curious.
Is there a compelling cite that anyone can find? I have tried googling six ways to Sunday to establish that they are bad, but I can’t find anything outside of stuff like YouTube videos.
Surely some credible health authority somewhere on the planet has published findings that demonstrate harm/toxicity from microwaving frozen dinners.
PubMed is always a good source. This came up immediately, though there are many other papers on the subject:
This study investigated the release of microplastics and nanoplastics from plastic containers and reusable food pouches under different usage scenarios, using DI water and 3% acetic acid as food simulants for aqueous foods and acidic foods. The results indicated that microwave heating caused the highest release of microplastics and nanoplastics into food compared to other usage scenarios, such as refrigeration or room-temperature storage. It was found that some containers could release as many as 4.22 million microplastic and 2.11 billion nanoplastic particles from only one square centimeter of plastic area within 3 min of microwave heating. Refrigeration and room-temperature storage for over six months can also release millions to billions of microplastics and nanoplastics. Additionally, the polyethylene-based food pouch released more particles than polypropylene-based plastic containers. Exposure modeling results suggested that the highest estimated daily intake was 20.3 ng/kg·day for infants drinking microwaved water and 22.1 ng/kg·day for toddlers consuming microwaved dairy products from polypropylene containers. Furthermore, an in vitro study conducted to assess the cell viability showed that the extracted microplastics and nanoplastics released from the plastic container can cause the death of 76.70 and 77.18% of human embryonic kidney cells (HEK293T) at 1000 μg/mL concentration after exposure of 48 and 72 h, respectively.
I’m not aware of them being banned anywhere. The data is suggestive, not conclusive. That microplastics are emitted (and enhanced with heat) is certain. Not to mention other chemicals leaching into the food. But how bad is it, actually? No one knows yet.
Maybe? It is a topic of research. No one thinks it is good for you but…maybe…it is not actually bad for you either. I dunno.
Public concerns over the health effects of microplastics are growing. In the past year alone, headlines have sounded the alarm about particles in tea bags, seafood, meat, and bottled water. Scientists have estimated that adults ingest the equivalent of one credit card per week in microplastics. Studies in animals and human cells suggest microplastics exposure could be linked to cancer, heart attacks, reproductive problems, and a host of other harms. Yet few studies have directly examined the impact of microplastics on human health, leaving us in the dark about how dangerous they really are.
ETA: A “credit card per week” of ingested plastics seems unlikely to me but I didn’t do any research.
Yeah, it’s nonsense. The figure comes from this paper, which seems legit enough:
Subsequently, we estimated that globally on average, humans may ingest 0.1–5 g of microplastics weekly through various exposure pathways.
The “credit card” estimate comes from the 5 grams. But it’s basically totally bogus:
Researchers at Wageningen University released a study questioning the Newcastle findings. Their study published in March 2021 accounted for the size ranges and particle shapes when pulling data from other studies. The researchers obtain a median plastics consumption through microparticles of only about 4.1 µg per week for adults — a million times less than 5 g.
I read the abstract of the article, and wonder if it’s the microwaving that’s uniquely bad, or if any heating-in-plastic option (baking in a toaster oven or sous vide) with lots of plastic surface area being in direct contact with food would have similar results.
I had a similar thought. I was thinking if microwaving is bad, most frozen dinners do have directions for how to heat them up in the oven. But then I immediately thought it’s the heat itself that’s bad, not the mechanism of heating.
But I’m wondering about the scale. Given how much micro plastics we have in our systems just by living on earth, how many frozen dinners would you have to eat to move the needle in a non-negligible way? Ten? A thousand? A million?
It’s possible that eliminating frozen dinners entirely might be the microplastics equivalent of rearranging deck chairs on the Titanic.
EDIT: Heating a frozen dinner in the oven in the little plastic tray has to be worse, right? You typically have to cook them five times as long in the oven, and the oven almost certainly heats up the plastic directly much more than a microwave does. Would a microwave even heat up an empty plastic tray at all? An oven certainly will.
First of all, DO NOT MICROWAVE FOODS IN PLASTIC. “Higher temperatures facilitate the leaching of chemicals and the release of microplastics,” says Martin Wagner, a biologist studying plastic exposure at the Norwegian University of Science and Technology.
So again, it seems that surface area exposed to plastic and HEAT rather than the microwave itself are the biggest issue. With other issues, such as acidic and high-fat foods having a higher chance to coax chemicals/microplastics into the food.
So, unsurprisingly, the Microwaving plastic being bad is an oversimplification. There are a variety of risks, and certain habits/foods are riskier than others. So heating food and drink in plastic containers is an avoidable risk, though the degree of risk is still under evaluation.
Sounds like the popular sous vide cooking option would be worse in many ways - because you have heat, full contact with your food, and much longer cooking times than most microwaved options.
That sucks, I was strongly considering an immersion cooker.
One point to keep in mind is that plastic isn’t a substance. It’s a very large category of a great many different substances, with a wide variety of physical and chemical properties. Some plastics are definitely a bad combination with heated food… and so those generally aren’t used in those contexts. Others, there’s no evidence that they’re dangerous.
It may be that the plastic tray used for a frozen meal is approved for use, one time, to cook or reheat that meal, but not for repeated use. I sometimes get take-out food in plastic trays and some are labeled as microwave-safe but I think some are labeled as not.
Lots of plastics are unhealthy even without microwaving. Today I was reading this article:
Led by researchers at NYU Langone Health, the current study focused on a kind of phthalate called di-2-ethylhexyl phthalate (DEHP), which is used to make food containers, medical equipment, and other plastic softer and more flexible. Exposure has been shown in other studies to prompt an overactive immune response (inflammation) in the heart’s arteries, which, over time, is associated with increased risk of heart attack or stroke. In their new analysis, the authors estimated that DEHP exposure contributed to 356,238 deaths, or more than 13% of all global mortality from heart disease in 2018 among men and women ages 55 through 64.
No cites, but I’m just going to throw in two comments.
One is that a major and potentially very significant difference between microwaving a frozen dinner and heating it in the oven is the time it spends in a hot environment, giving whatever leaches out of the plastic more time to do its bad stuff (say, five minutes versus half an hour or more). That said, I’m still going to oven-bake fried chicken dinners! Not interested in soggy fried chicken, and it hasn’t killed me yet!
The other point is that I’ve seen many plastic food containers labeled as “single use”. Implying that nothing particularly bad will happen if the contents is heated as directed, but if you keep re-using them, you may get more and more unwanted chemicals leaching out.
I just opened a frozen dinner for tonight and was pleased to see that it was in a sort of paperboard tray. I hope that this is a growing trend. The paper can either be rinsed and recycled or sent out for composting. Much preferable to plastic.
ETA: Obviously, this only works for microwave-only products.
That’s surprising, But then, OTOH, I frequently use parchment paper for baking, and at far higher temperatures than recommended. The worst that happens is that the edges get a bit scorched.
I’d much rather have an outlying edge of scorched parchment paper than deadly chemicals leaching into my food!