Microwaves and Plastic: A Dangerous Combo

By Dr. Mercola

I don’t recommend storing your food in plastic or cooking it in a microwave, but if you’re going to use either, at least don’t use them together. Microwaving food in a plastic container virtually guarantees that your food will be contaminated with plastics chemicals that have leached into your food during the heating process.

There’s no arguing that plastic is convenient, inexpensive, and virtually unbreakable, making it tempting to use for food storage, especially while you’re out and about. However, though it seems perfectly safe, plastic is made with a veritable stew of chemicals.

What’s Lurking in Your Plastic Containers?

Depending on what product you’re using, your plastic might contain phthalates, for starters. Phthalates are a group of "gender-bending" chemicals causing males of many species to become more female.

These chemicals have disrupted the endocrine systems of wildlife, causing testicular cancer, genital deformations, low sperm counts, and infertility in a number of species, including polar bears, deer, whales, and otters, just to name a few.

In humans, phthalates have been linked to preterm birth and neurobehavioral problems in infants after in-utero exposure.¹ They’ve also been found to increase blood pressure levels,² and high urinary levels are associated with insulin resistance, which can lead to diabetes.³

Plastic containers may also contain bisphenol-A (BPA) or any one of its similar “replacement” chemicals, including BPS (there’s also Bisphenol B, C, E, F, G, M. P, PH, TMC, and Z).

While the replacement chemicals haven’t been widely studied, BPA is a known endocrine disruptor that’s been linked to a number of health concerns, particularly in pregnant women, fetuses, and young children, but also in adults, including:

What else might be lurking in your plastic? Commercial-grade cling wrap (which may be used to wrap cheese or other deli items) may be made from polyvinyl chloride (PVC), which is known to cause cancer. The manufacture of PVC also leads to the formation of dioxin, another carcinogen.

Styrofoam food trays, egg cartons, carryout containers, and opaque plastic cutlery may contain yet another chemical known as styrene, which has been classified as a possible human carcinogen by the International Agency for Research on Cancer (IARC).

Heating Accelerates the Transfer of Chemicals to Your Food

In a study of common plastic products, 70 percent tested positive for estrogenic activity, which means they’re capable of disrupting your hormone levels.⁴ However, that was before researchers subjected them to conditions in which they’re actually used.

Under real-world conditions like running the plastics through a dishwasher or heating them in a microwave, 95 percent tested positive for estrogenic, hormone-disrupting activity.

While regular use, such as washing in a dishwasher and scratches, has been found to increase the rate of chemical leaching, heat appears to be the worst offender of all, increasing the rate of chemical transfer by up to 55-fold. As written in the journal Toxicology Letters:⁵

“Using a sensitive and quantitative competitive enzyme-linked immunosorbent assay, BPA was found to migrate from polycarbonate water bottles at rates ranging from 0.20 ng/h to 0.79 ng/h.

At room temperature the migration of BPA was independent of whether or not the bottle had been previously used. Exposure to boiling water (100 degrees C) increased the rate of BPA migration by up to 55-fold.”

In the US, the National Institute of Environmental Health Science recommends consumers avoid microwaving food in plastic containers because heat increases the likelihood of chemical leaching.⁶

Plastic ‘Microwaveable’ Containers Increase Your Risk of High Blood Pressure

The US Food and Drug Administration (FDA) recommends any plastic containers you use in the microwave should be labeled for microwave oven use.⁷ But such containers may not be much safer than standard plastics.

“Microwaveable” containers may be formulated with supposedly “safer” chemicals. Diisononyl phthalate (DINP) and diisodecyl phthalate (DIDP), for instance, have been used to replace di-2-ethylhexylphthalate (DEHP), an endocrine-disrupting phthalate known to cause reproductive toxicity.

DEHP is highly lipophilic (fat soluble), and when used in PVC plastic is only loosely chemically bonded to the plastic. It readily leaches into blood (when used in IV tubing, for example) or other lipid-containing solutions in contact with the plastic.

DINP and DIDP have been touted as safer alternatives, but they, too, have been linked to health concerns, including high blood pressure.⁸ Microwaving food in #7 polycarbonate plastic, in particular, should be avoided, even if it is labeled microwave-safe.

According to the National Resources Defense Council (NRDC):⁹

“What the term ‘microwave-safe’ basically means is that any chemicals leaching from the container into food do so at levels far below those shown to have any health effects.

There is cause to be wary of this claim, however. In particular, #7 polycarbonate plastic should not be used in a microwave, even if it is labeled ‘microwave-safe,’ because it leaches hormone-disrupting bisphenol A (BPA), especially when heated.”

I would expand this to say that there is really no such thing as “microwave-safe” plastic. There are many chemicals that could potentially leach into your food, and it’s unclear which are tested for and what levels are deemed “safe” for consumption.

For instance, the Nutrition Action Newsletter reported the leakage of numerous toxic chemicals from the packaging of common microwavable foods, including pizzas and popcorn. Chemicals included polyethylene terephthalate (PET), benzene, toluene, and xylene.

Microwaving fatty foods in plastic containers also leads to the release of dioxins and other toxins into your food.^10,11 You’re far better off heating your food in glass or ceramic containers – and not in a microwave at all.

Why You Might Want to Rethink Microwave Cooking

At the very least, banish all plastic products (containers, plastic wrap, food wraps, etc.) from ever seeing the inside of your microwave. Even better, banish your microwave altogether.

Microwaves heat food by causing water molecules in it to resonate at very high frequencies and eventually turn to steam, which heats your food. While this can rapidly heat your food, it also causes a change in your food's chemical structure. The first thing you probably noticed when you began microwaving food was how uneven the heating is.

"Hot spots" in microwaved food can be hot enough to cause burns — or build up to a "steam explosion." This has resulted in admonitions to new mothers about NOT using the microwave to heat up baby bottles, since babies have been burned by super-heated formula that went undetected (not to mention the issue with plastic toxins leaching into the milk).

Microwaving distorts and deforms the molecules of whatever food or other substance you subject to it. An example of this is blood products. Blood is normally warmed before being transfused into a person. Now we know that microwaving blood products damages the blood components.

In fact, one woman died after receiving a transfusion of microwaved blood in 1991, which resulted in a well-publicized lawsuit. Further, when you heat food in a microwave, it can zap the nutrition right out of your food. Some excellent scientific data has been gathered regarding the detrimental effects of microwaves on nutrients:

19 Tips to Reduce Your Chemical Exposure at Home

In the US, chemicals are considered safe until proven otherwise. You don’t want to risk your health by exposing yourself to these toxins unnecessarily, especially in your food but also in your personal care products and goods around your home. Implementing the following measures will help you avoid the worst endocrine-disrupting culprits as well as other chemicals from a wide variety of sources. To sum it up, try to stick with whole foods and natural products around your home.

The fewer ingredients a product contains, the better, and try to make sure anything you put on or in your body – or use around your home – contains only substances you’re familiar with. If you can’t pronounce it, you probably don’t want it anywhere near your family.

1. As much as possible, buy and eat organic produce and free-range, organic meats to reduce your exposure to added hormones, pesticides, and fertilizers. Also avoid milk and other dairy products that contain the genetically engineered recombinant bovine growth hormone (rBGH or rBST).
2. Rather than eating conventional or farm-raised fish, which are often heavily contaminated with PCBs and mercury, supplement with a high-quality omega 3, or eat smaller fish or fish that is wild-caught and lab tested for purity. Wild caught Alaskan salmon is about the only fish I eat for these reasons.
3. Buy products that come in glass bottles or jars rather than plastic or canned, since chemicals can leach out of plastics and into the contents.
4. Store your food and beverages in glass rather than plastic, and avoid using plastic wrap.
5. Use glass baby bottles and avoid plastic sippy cups for your little ones.
6. Eat mostly raw, fresh foods. Processed, prepackaged foods (of all kinds) are a common source of chemicals such as BPA and phthalates.
7. Replace your non-stick pots and pans with ceramic or glass cookware.
8. Filter your tap water — both for drinking and bathing. If you can only afford to do one, filtering your bathing water may be more important, as your skin absorbs contaminants. To remove the endocrine-disrupting herbicide Atrazine, make sure the filter is certified to remove it. According to the Environmental Working Group (EWG), perchlorate can be filtered out using a reverse osmosis filter.
9. Look for products that are made by companies that are earth-friendly, animal-friendly, green, non-toxic, and/or 100% organic. This applies to everything from food and personal care products to building materials, carpeting, paint, baby items, upholstery, and more.
10. Use a vacuum cleaner with a HEPA filter to remove house dust, which is often contaminated with traces of chemicals.
11. When buying new products such as furniture, mattresses, or carpet padding, ask what type of fire retardant it contains. Be mindful of and/or avoid items containing PBDEs, antimony, formaldehyde, boric acid, and other brominated chemicals. As you replace these toxic items around your home, select those that contain naturally less flammable materials, such as leather, wool, and cotton.
12. Avoid stain- and water-resistant clothing, furniture, and carpets to avoid perfluorinated chemicals (PFC’s).
13. Minimize your use of plastic baby and child toys, opting for those made of natural wood or fabric instead.
14. Only use natural cleaning products in your home or make your own. Avoid products that contain 2-butoxyethanol (EGBE) and methoxydiglycol (DEGME) — two toxic glycol ethers that can damage fertility and cause fetal harm.¹⁷
15. Switch over to organic brands of toiletries such as shampoo, toothpaste, antiperspirants, and cosmetics. You can replace many different products with coconut oil and baking soda, for example. EWG has a great database¹⁸ to help you find personal care products that are free of phthalates and other potentially dangerous chemicals. I also offer one of the highest quality organic skin care lines, shampoo and conditioner, and body butter that are completely natural and safe.
16. Replace feminine hygiene products like tampons and sanitary pads with safer alternatives.
17. Avoid artificial air fresheners, dryer sheets, fabric softeners, or other synthetic fragrances.
18. Look for products that are fragrance-free. One artificial fragrance can contain hundreds – even thousands – of potentially toxic chemicals.
19. Replace your vinyl shower curtain with one made of fabric.