About 4.2 trillion gallons of water are seen in the United States each year, but about 90% immediately evaporates or goes into the ocean (McCuen, 1986). In 1974, Congress passed the Safe Drinking Water Act after a national debate over the amount of organic chemicals such as chloroform and benzene in U.S. drinking water (McCuen, 1986). One of the other groundwater contaminants is fluoride. There is not much fluoride in the elemental state due to its high level of radioactivity and it exists as fluorides in minerals and water (WHO, 2004). Fluoride was introduced into water during the second half of the 20th century and is one of the two most recent developments in drinking water (Barzilay, 1999). Fluoride is used for protection against cavities and other dental caries and binds to tooth enamel (Barzilay, 1999). Fluoridation is a beneficial achievement for public health and early experiments with it have established that fluoride is an effective and cost-effective method of aiding public health. This cost-effective method of fluoridation costs citizens on average only 30 cents to $2 per year (Walker, 1978). However, only a small amount of the fluoridated water pumped each year reaches people's mouths; because most of the water ends up being used for doing personal things like washing dishes. A fluoride concentration of 1 milligram per liter is the ideal amount of fluoride to prevent tooth decay, although some of the side effects of fluoride in humans can be dangerous if consumed in concentrations that are too high. Is your water fluoridated? At the end of the 20th century more than 60% of the American population used fluoridated water. Approximately...... middle of paper ......lower and where the climate is generally humid and wet, the concentration of fluoride in water is generally higher. Fluoride, when consumed correctly, can be beneficial to your health, but if not consumed properly, it can cause serious health problems and even death. Works Cited Barzilay, JI (1999). The water we drink. New Brunswick, NJ: Rutgers University Press. Langwith, J. (2010). Water. Farmington Hills, MI: Greenhaven Press. McCuen, G.E. (1986). Protect water quality. Hudson, Wis.: GEM Publications. Walker, R. (1978). Water supply, treatment and distribution. Englewood Cliffs, NJ: Prentice-Hall, Inc. WHO. (2000). Chapter 6.5 Fluorides, World Health Organization (WHO), Regional Office for Europe, Copenhagen, Denmark.WHO. (2004). Fluoride in drinking water. Retrieved from http://www.who.int/water_sanitation_health/dwq/chemicals/fluoride.pdf