Here's some info I have posted in the past about Pyrex and Anchor Hocking that points out the change to a cheaper and potentially dangerous forumla:
For anyone who wants an UNBIASED account of the development and changes in Pyrex and Anchor Hocking, it would behoove them to read the Consumer Reports article entitled "Glass Bakeware That Shatters" in its January 2011 issue and not depend solely on the manufacturer's own website.
The Consumer Reports in-depth five-page analysis was a year in the making and includes the history of the glassware, the results of their lab tests on the current Pyrex and Anchor Hocking products made in the U.S. and those made in Europe, a series of interviews with people severely injured from shattered glass bakeware, suggestions for consumers' safety when using the bakeware, and a plea for government action, primarily because the two companies have been reluctant to address the problems but instead have taken a "blame the victim" stance.
Yes, World Kitchen does claim that Pyrex has consistently been made of soda lime glass for 60 years. However, Sarah Horvath, a Corning spokewoman, states that Corning made Pyrex out of both soda lime and borosilicate before selling to World Kitchen in 1998. And a former executive scientist with Corning, P. Bruce Adams, says that borosilicate was still being used by Pyrex when he retired in 1987. So it is not at all clear when the switch took place.
The important point is that strengthened or not, the cheaper soda lime version tested much more poorly than did the more expensive borosilicate glass, which by the way, is still made in Europe by the company that bought the rights from Pyrex in 1994.
This information is not really new, but it is delineated clearly and thoroughly in this Consumer Reports article. It is worth reading before deciding to buy Pyrex or Anchor Hocking glass bakeware. And the sidebar on reducing the risks if one does decide to buy and use the product is invaluable.
A google search of "Pyrex dangers" will verify this information.
~Who in the world am I? Ah, that's the great puzzle~ Lewis Carroll, Alice in Wonderland