Grand Rapids, Mich., became the first U.S. city to begin fluoridating the drinking water. With the intention of reducing tooth decay, one part per million of fluoride was added to the water supply. Fluorine is the 13th most abundant element on earth, found in nature in its ionic form - fluoride - in combination with other elements, such as calcium, magnesium, phosphates etc. This fluoride is present in small yet varying amounts in almost all soils, water supplies, plants, and animals and, therefore, is a normal constituent of all diets. In mammals, the highest concentrations are found in the bones and teeth. Decades after the conclusion of the Grand Rapids fluoridation study, fluoride continues to be dental science's main weapon in the battle against tooth decay.

France inaugurated its first operational solar generating plant at Odeillo in the Pyranees of southwestern France. Its output of 64 kilowatts (sufficient to power about 1,000 60-watt light bulbs), was connected to the national electricity grid to demonstrate operational solar power. The plant was part of the huge solar furnace project run by the National Center for Scientific Research. The site was built for high-temperature research using an eight-story parabolic mirror to refocus sunlight from an extensive field of mirrors on a hillside in front of it, with 63 moveable mirror arrays designed to follow the motion of the sun. The electricity was generated by a turbo-alternator driven by steam from a boiler at the focus of the reflected sunlight. Alignment of the mirrors began in May 1969.