Family safety warning: Glass bakeware that shatters

If you're planning to do some family baking this week or next, read on.

Pyrex and other brands of glass bakeware are a staple of many kitchens, with marketing that dates back decades, touting its versatile uses. In recent years, news reports and Internet postings about glass bakeware unexpectedly shattering have some consumers worried about safety and confused about instructions. Packaging may prominently say freezer-safe and oven-safe. But consumers might not be aware of warnings which can appear on the back of a label in type this small with cautions about preheating the oven, cooling, use of liquids in the pan, and more. (See frame-by-frame still photos of glass bakeware shattering in our labs).

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. (Learn more about how manufacturers blame the victims of exploding bakeware.)

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.

Learn more in the full glass cookware report.