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Pyrex Cookware May Explode and Injure You

pyrexAbout 5:30 PM there was a loud bang from the oven. Sylvia opened the oven door and the Pyrex dish had shattered into a million pieces…”

TRUE says Snopes.

Consumers have been noticing for years that sometimes their Pyrex brand cookware unexpectedly breaks during or shortly after use, often with such shatterings occurring in rather eruptive form. It is not unheard of for a Pyrex dish to suddenly “explode” while sitting in a hot oven or soon after it has been taken from one and is resting on a counter.

As to what might be the cause of so many shatterings, one possible explanation is that while Pyrex products were originally made of borosilicate glass, the company’s products now vended in the North American market are fashioned of tempered soda-lime glass, a cheaper material.

To see the video "Testing Pyrex: Experts Weigh In," please see this link.

Dr. Mercola's Comments:

Pyrex has been one of the most popular brands of kitchen glassware for almost a century.

It was invented in 1913 when Bessie Littlejohn, the wife of the vice president of Corning Glass Works, asked her husband to bring home something from the factory that could be used as a piece of oven-safe cookware. After two years of product development, a full line of glass baking dishes was marketed to the public. After only four years, more than 4.5 million pieces of Pyrex had been sold, and its popularity has steadily marched on.[1]

Pyrex glass was even used for other applications over the years, including the windows of the space capsules for NASA’s Gemini and Apollo missions in the 1960s and 1970s.

Pyrex as Improvised Explosive Device

So why are you suddenly hearing reports of Pyrex exploding? (To see the video "Testing Pyrex: Experts Weigh In," please see this link.)

The Pyrex products now sold by Wal-Mart are NOTt the same Pyrex products your mother and grandmother received as wedding gifts.

Most people have no idea that Corning actually sold Pyrex to a company called World Kitchen in 1998. But even prior to that, the U. S. industry as a whole switched from borosilicate to soda lime glass in the 1980s, for a number of reasons:

  • Soda lime glass is easier to melt and work with (fewer deformities in the glass).

  • The raw materials for soda lime glass cost less than those of borosilicate glass (especially pricey boron).

  • Borosilicate glass produces far more emissions from a glass furnace and puts far more boric acid into the water and the soil.

  • Companies don’t want to outlay the funds needed to install multi-million dollar filtration systems to decrease boric acid pollution.

  • Glass furnaces have a longer lifespan firing soda lime glass because the energy requirements are 15 to 20 percent lower than for borosilicate glass.

The conversion to soda lime glass was simply far more profitable for all the reasons described above.

Pyrex for the kitchen is now made from heat-treated soda lime glass, although the Pyrex sold in Europe is still made of borosilicates. If you have a Pyrex dish that is more than 25 years old, there is a good chance it contains borosilicate glass.

Heat-treated lime isn’t able to withstand temperature changes the way the old borosilicate glass could. Soda lime glass undergoes three times the thermal expansion of borosilicate glass, which is why a hot soda lime dish placed on a cold, wet surface turns your baking dish into a virtual thermal bomb.

This also explains why borosilicate is still the type of glass used for laboratory glassware.

Bakeware With a Temper

What World Kitchens will tell you is that heat-treated soda lime glass has twice the mechanical strength of borosilicate—less likely to break when you drop it—which is the most common way people get injured from glass bakeware, according to emergency department records.

World Kitchens blames Pyrex shatterings on consumers for not reading the fine print on the product label about avoiding sudden temperature changes. Yet, the product packaging ALSO says that it is “freezer safe…microwave safe…dishwasher safe…oven safe.”

Dr. Steve Friedman, an expert on brittle materials formerly with the National Institute of Science and Technology, said the glass used in today’s Pyrex products may not be tempered properly, making it more likely to explode than products sold under the Pyrex label in European countries[2] .

The manufacturer denies this, stating that it has an “exemplary” safety record.

But the record is anything BUT exemplary.

People who have had their Pyrex dishes “explode” report large shards of glass being ejected at high speeds, and photos and independent tests back up their claims. If the glass were tempered properly, this wouldn’t be happening.

World Kitchen states that tempered soda lime is more resistant to mechanical breakage. But Hank Chamberlain, president of Allied Glass Experts, a glass consulting and testing company, said this is not necessarily true. That toughness only exists in unchipped and unscratched tempered glass. In a kitchen environment, these conditions aren’t the norm.

Chamberlain goes on to say:

We're not having trouble with people dropping these things on the tile floor and cutting their toes. We're having trouble with people taking them out of the oven and having them blow up and put scalding food on them. People understand that if you drop a piece of glass, it’s likely to break. They don’t understand that it’s likely to blow up when you take it out of the oven.”2

Chamberlain independently tested eight Pyrex dishes. He found that the tempering was uneven, and there was “quite a bit of inconsistency within the pieces.” He went on to say that he was “absolutely certain that they have less core tension and therefore less residual surface compression than fully tempered glass. This stuff produces some wicked-looking big shards,” Chamberlain exclaims.

It is also important to point out that tempered glass can lose its temper when heated, if you’ll pardon the pun.

Chamberlain and one other glass expert expressed serious doubts that tempered soda lime glass could maintain a thorough temper after numerous heating and cooling cycles in the normal home kitchen. And when the glass loses its temper in some areas, the stresses from uneven temperatures could result in the violent explosions we’ve been hearing about lately.

Manufacturer Plays Dumb

According to CBS 2, the Consumer Product Safety Commission has received 66 Pyrex safety complaints over the last ten years. Other consumer product agencies have collected about 300 complaints about Pyrex over the last five years.[3] has had complaints from every major English-speaking country where World Kitchen products are sold including Canada, New Zealand, and Australia.2

Interestingly, there has been only one report of a European Pyrex dish exploding, according to a spokeswoman for Arc International, who manufactures Pyrex for the European Union. Arc International’s Pyrex dishes are made from borosilicate glass and are sold for about twice the cost of World Kitchen’s dishes.

Warning: It is NOT Just Pyrex You Need to Be Aware of

And it’s not just Pyrex that’s exploding.

Anchor Hocking, a manufacturer of similar dishes made of soda lime glass, has generated 48 complaints in the database. A representative of Anchor Hocking said tempered soda lime is safer than borosilicate because it does not break into large dangerous shards.2

This probably isn’t very consoling to a woman who lost her eyesight for months after an Anchor Hocking dish exploded while she was standing over it, embedding shards of glass into her face and into the ceiling above her head.

In the word of James Hood, writer for, the party line with these companies is essentially:

“There are no known defects in our products. If we knew of defects and did not fix them, then we would be liable for damages from their use. Therefore, we don’t know of any such defects.”

It’s very similar to Ford Motors not knowing about failing head gaskets in Windstar engines, or Merck not knowing that Vioxx caused heart attacks.

Considering that there have been 370 million Pyrex glass products manufactured since 1998, the reports of exploding dishes represent a very small percentage of the overall rate of usage. Granted, not everyone whose Pyrex dish becomes an IED is going to report it. But now that the story is out, reports are coming in with increasing frequency (you can read many of them for yourself at

These figures reported by The Stats Blog give some perspective on the scope of the problem[4]:

  • Based on emergency department data for 2005, you had a 1 in 3.7 million chance of sustaining a non-fatal injury from glass bakeware that was NOT a result of dropping it.

  • In 2006, you had a zero percent risk.

  • In 2006, your risk for sustaining an injury from operating a blender was 1 in 95,152…you know, those moving blades.

I could not find any statistics about other kitchen accidents, but stunts like cutting yourself with a knife or scalding yourself with boiling water have got to be among the most common.

The point is, there are plenty of kitchen hazards to be aware of without worrying about your dishes blowing up. Indestructibility and perfect safety are not the only standards for measuring risk.

Pyrex Dangers Pale in Comparison to Teflon, Iron and Aluminum Cookware

The far greater danger posed by your cookware is the toxins it could be leaching into your food.

Many more people are cooking with pans and utensils that pose a risk to their health on a daily basis than those whose bakeware is exploding. Non-stick pans with Teflon and other coatings begin releasing toxin fumes into the air at a temperature of 446 degrees Fahrenheit, causing potentially serious health problems.

Teflon coated aluminum contains perfluorooctanic acid (PFOA), a synthetic compound that creates a slippery soap-like finish, which helps your eggs not stick. But Teflon is highly suspected to cause health problems from your immune system to problems with childbirth.

Although non-stick cookware often goes by the brand name Teflon, watch for other non-stick brands with the same coating including Silverstone, Fluron, Supra, Excalibur, Xylon, Duracote, Resistal, Autograph and T-Fal.

In animal studies, PFOAs were linked with organ damage, including brain, prostate gland, liver, thymus gland, and kidneys. Some of the laboratory rats died as a result of the PFOA exposure. PFOA has been implicated in cancer of the pancreas, liver, testicles, and mammary glands, as well as miscarriages and thyroid problems. Even PFOA plant workers are showing an increased rate of prostate cancer.

And you very likely have PFOAs in your own body since the CDC found evidence of them in 98 percent of the population, including 100 percent of newborns tested.

DuPont, being the patented manufacturer of Teflon, is right in the middle of the controversy, having already been fined $10.25 million by the Environmental Protection Agency (EPA) for hiding health data about PFOA for twenty years.

Other cookware materials are not much better. Aluminum is a reactive metal and suspected causal factor in Alzheimer’s disease.

Even stainless steel, which was long thought to be completely non-reactive, has been found to leach metals into your food and cause some serious allergic reactions. In a study conducted on heart patients receiving stainless steel stents, restenosis occurred in 50% of patients. Allergies to the nickel and molybdenum in the stainless steel were suspected to have caused this.

And those metals have been found to leach into foods in small quantities when cooking with stainless steel.

So, What IS Actually Safe to Cook With?

The best option I have found is the high-fired ceramic cookware I now offer through my website, called Mercola Healthy Cookware. It is made from inorganic natural materials and is extremely safe because it’s non-reactive and non-toxic. No odors or gases release into the air during cooking, even when temperatures exceed 2500 degrees F.

It has a high-tech nanoglaze that is completely nonporous and extremely durable.

It’s environmentally friendly, and manufactured using clean burning natural gas. And it has a 50-year warranty against any breakage from thermal shock.

And so far, we’ve had no explosions.

I have been using it myself for a couple of years now and am convinced it is simply the best cookware in the market today and is the only cookware I use. I love it so much I have given sets to many of my friends and relatives.

Simple Kitchen Tips for Minimizing Pyrex-Pyrotechnics

If you have glass bakeware and want to continue using it, Consumer Affairs offers a few tips for minimizing your risk for glass ovenware disasters[5]:

  1. Wear oven gloves, which will offer some protection if a dish breaks in your hands.

  2. Wear shoes or slippers in the kitchen.

  3. Keep the dish away from your face.

  4. Keep kids and dogs away from the cooking area; never allow kids to cook unsupervised.

  5. Set bakeware dishes down gently.

  6. Preheat your oven before putting your baking dish into it. Some ovens use the top heating elements (the “broil” feature) during the preheat cycle, which can subject your cold dish to excessive thermal shock.

  7. Avoid putting objects on the stove unless you intend to cook them; even with the burners off, significant heat can radiate up from the oven to the stovetop.

  8. Discard any glass oven dish that has a crack, chip or deep scratch since these can serve as triggers for uneven heating or cooling and lead to a mishap.

The kitchen can be a dangerous place, although we tend not to think of it that way.

Just use some common sense and be aware that glass can be a hazard if not handled with care, whether it’s a car window or a casserole dish. Seriously consider replacing your cast iron, Teflon, and aluminum cookware if you want to eliminate one more obstacle to your goal of better health.

[1]K. Kennedy, “The history of Pyrex,”

[2] J. Enoch, “Three years later: Pyrex dishes still go boom: Government safety agency mum, company blames victims for cuts, burns,” August 20, 2008,

[3] “CBS sweeps week shocker: Glass can break!” The Stats Blog

[4] “Does Pyrex ‘explode’ because the manufacturer changed the mix? CBS Chicago’s epic investigation continues,” The Stats Blog

[5] J. Hood, “Pyrex panic: Shrapnel in the kitchen,” March 27, 2006