Pyrex glass bakeware has been made using the same soda lime composition and heat-strengthening process for more than 60 years. Pyrex glass bakeware was originally made from borosilicate glass in 1915, and in the 1940s Pyrex glass bakeware started being made from soda lime. Today, Pyrex glass bakeware is made at the same soda lime plant in Charleroi, Pennsylvania, and has not changed the manufacturing process or soda lime composition. While both soda lime and borosilicate are appropriate compositions for glass bakeware, heat strengthened or tempered, soda lime glass is more resistant to impact breakage – the far more likely cause of consumer injury. According to the U.S. Consumer Product Safety Commission’s National Electronic Injury Surveillance System data, consumers are far more likely to be injured by dropping glass bakeware than from breakage caused by sudden or uneven temperature changes. Additionally, Pyrex glass bakeware is heat strengthened to increase its resistance to breakage caused by impact or sudden, uneven temperature changes.