In 1974, Drs. Frank Sherwood Rowland and Mario J. Molina proposed that chlorofluorocarbons, used as propellants in aerosol sprays, contributed to the depletion of Earth's ozone layer. In response to this theory, the U.S. Congress passed amendments to the Clean Air Act in 1977 authorizing the Environmental Protection Agency to regulate the presence of CFCs in the atmosphere. The United Nations Environment Programme called for ozone layer research that same year, and, in 1981, authorized a global framework convention on ozone layer protection. In 1985, Joe Farman, Brian G. Gardiner, and Jon Shanklin published the first scientific paper detailing the hole in the ozone layer. That same year, the Vienna Convention was signed in response to the UN's authorization. Two years later, the Montreal Protocol, which regulated the production of CFCs was formally signed. It came into effect in 1989. The U.S. formally phased out CFCs in 1995.