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 "Federal Register" that all landfills would eventually leak and should only be used as a stopgap measure. Years of research and empirical knowledge of the failures of the Warren County PCB landfill led citizens of Warren County to conclude that the EPA's dry-tomb landfill design and regulations governing the disposal of toxic and hazardous waste were not based on sound science and adequate technology. Warren County's citizens concluded also that North Carolina's "1981 Waste Management Act" was scientifically and constitutionally unacceptable because it authorized the siting of toxic, hazardous and nuclear waste facilities prior to public hearings, preempted local authority