Heat pump the brand name Freon, a trademark of DuPont. Its manufacture is now banned or severely restricted by the Montreal Protocol of August 1987 because of the damage that CFCs cause to the ozone layer if released into the atmosphere. One widely adopted replacement refrigerant is the hydrofluorocarbon (HFC) known as R-134a (1,1,1,2-tetrafluoroethane). Heat pumps using R-134a replaced R-12 (dichlorodifluoromethane) and have similar thermodynamic properties but with insignificant ozone depletion potential and a somewhat lower global warming potential. Other substances such as liquid R-717 ammonia are widely used in large-scale systems, or occasionally the less corrosive but more flammable propane or
Toxic Substances Control Act of 1976 later explained during a 1975 Congressional Testimony, "While some authority exists to control the production of certain categories of toxic substances, such as pesticides, drugs, and food additives, most existing Federal authorities are designed to prevent harmful exposure only after the substances have been introduced into production." In Order to adequately regulate what chemicals should enter the environment, CEQ recommended that the government create a more comprehensive chemical policy to identify and control the chemicals that are manufactured, produced, and used in the U.S economy. Specifically, CEQ recommended that TSCA strengthen government oversight by requiring the following measures: First, manufacturers