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
Clothianidin report it was stated that clothianidin should not present a direct acute or chronic risk to freshwater and estuarine/marine fish, or a risk to terrestrial or aquatic vascular and nonvascular plants. It is considered to be toxic to aquatic invertebrates if disposal of wastes according to disposal instructions are not followed. The Pest Management Regulatory Agency of Canada lists it as "very highly toxic" to aquatic invertebrates, but only slightly toxic to fish. In the 2003 EPA report it was stated that although no water monitoring studies had been conducted, due to the extreme mobility and persistence of clothianidin in