In this report
A rash of complaints
Pyrex is born
A new formula
How we tested
Flying shards of glass
What the labels say
Blaming the victims
Next steps to take
Lab tests: Frame by frame
Reduce the risks
Shattering bakeware affects coworkers
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A retrospective of Consumer Reports and its place in the American consumer landscape.

A rash of complaints

Last reviewed: January 2011

The reports have generated enough buzz that World Kitchen, the Illinois-based manufacturer of Pyrex in the U.S., and its competitor Anchor Hocking—which own more than 75 percent of the glass bakeware market—have created pages on their websites aimed at debunking what they say are false and misleading reports.

To find out more about glass bakeware, Consumer Reports conducted a 12-month investigation that included testing in our labs and in outside labs, and gathering information from manufacturers, government agencies, experts, and consumers. Here's what we learned:

  • Consumers in scores of cases reported glass bakeware unexpectedly shattering, according to federal documents, court papers, and interviews. When we examined 163 incidents in detail, we discovered at least 42 reports of injuries. While hundreds of millions of dishes are used safely each year, we believe the situation is serious enough that we have asked the Consumer Product Safety Commission to investigate.
  • The American-made Pyrex and Anchor Hocking bakeware we tested, made from soda lime glass, shattered at lower temperatures in our tough heat tests than European-made pans, which are made of a more expensive glass, borosilicate. U.S. Pyrex and Anchor Hocking glass bakeware used to be made of borosilicate but no longer are.
  • When glass bakeware does shatter, consumers report, it can break into sharp shards that go flying, raising the risks of injuries. This contrasts with claims from one of the manufacturers that its glass bakeware breaks into "relatively small pieces generally lacking sharp edges."
  • While the dishes' packaging might tout their versatility for use in ovens, freezers, and microwaves, sometimes small print on the back contains many cautions about those very uses that are easy to miss.
  • Customer complaints have been regularly challenged by World Kitchen, the current maker of Pyrex in the U.S., in the reports we reviewed. Some consumers say the accidents they report were met with confusing advice about the proper ways to use the product.