"These contradictory results do not justify a classification of fluorine as an essential element, according to accepted standards.”
SOURCE: National Academy of Sciences. (1989). Recommended Dietary Allowances: 10th Edition. Commission on Life Sciences, National Research Council, National Academy Press. p. 235.

“fluoride is no longer considered an essential factor for human growth and development.”
SOURCE: National Research Council (1993). Health Effects of Ingested Fluoride. National Academy Press, Washington DC. p. 30.

“First, let us reassure you with regard to one concern. Nowhere in the report is it stated that fluoride is an essential nutrient. If any speaker or panel member at the September 23rd workshop referred to fluoride as such, they misspoke. As was stated in Recommended Dietary Allowances 10th Edition, which we published in 1989: ‘These contradictory results do not justify a classification of fluoride as an essential element, according to accepted standards.”
SOURCE: Alberts B, Shine K. (1998). Letter from Bruce Alberts, President, National Academy of Sciences, and Kenneth Shine, President, Institute of Medicine to Dr. Albert Burgstahler. November 18, 1998. (See letter)