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
Toxic waste such as batteries, used computer equipment, and leftover paints or pesticides. Toxic material can be either human-made and others are naturally occurring in the environment. Not all hazardous substances are considered toxic. The United Nations Environment Programme (UNEP) has identified 11 key substances that pose a risk to human health: The most overlooked toxic and hazardous wastes are the household products in everyday homes that are improperly disposed of such as old batteries, pesticides, paint, and car oil. Toxic waste can be reactive, ignitable, and corrosive. In the United States, these wastes are regulated under the Resource Conservation and Recovery