Period 6 element devices though concerns about the element's toxicity have led to mercury thermometers and sphygmomanometers being largely phased out in clinical environments in favor of alcohol-filled, galinstan-filled, digital, or thermistor-based instruments. It remains in use in scientific research applications and in amalgam material for dental restoration. It is used in lighting: electricity passed through mercury vapor in a phosphor tube produces short-wave ultraviolet light which then causes the phosphor to fluoresce, making visible light. Thallium is a chemical element with the symbol Tl and atomic number 81. This soft gray other metal resembles tin but discolors when exposed to air. The
Substantial equivalence conference of officials and industry), although the term "substantial equivalence" was not used. Adopting the term, "substantial equivalence" was formulated as a food safety policy by the OECD, first described in their 1993 report, "Safety Evaluation of Foods Derived by Modern Biotechnology: Concepts and Principles. The term was borrowed from the FDA's 1976 substantial equivalence definition for new medical devices—under Premarket Notification 510(k), a new Class II device that is essentially similar to an existing device can be cleared for release without further testing. The underlying approach of comparing a new product or technique to an existing one has long