Final answer:
Excessive fluoride intake leads to fluorosis, with the US EPA setting a maximum limit of 4 ppm for fluoride in drinking water. Fluorosis is most commonly caused by naturally high levels of fluoride in groundwater. Products like toothpaste also contain fluoride, contributing to the total intake but can lead to fluorosis when concentration levels are too high.
Step-by-step explanation:
Fluoride is a naturally occurring mineral that plays a crucial role in dental health. However, excessive fluoride intake can lead to fluorosis. The US Environmental Protection Agency has set a maximum level of 4 parts per million (ppm), or 4 mg/L, as the limit for fluoride in drinking water to prevent fluorosis, although fluoride levels are not regulated in all countries. Notably, other products such as toothpaste and mouth rinses also contribute to fluoride intake.
Areas with naturally high levels of fluoride in groundwater, which is utilized for drinking water, are at risk of dental and skeletal fluorosis, which can cause joints to stiffen and bones to thicken, affecting mobility and the thyroid gland. Water fluoridation is considered a cost-effective method of delivering fluoride to prevent tooth decay, with more than 75% of the US population having access to fluoridated water. Yet, about 100 million Americans do not have fluoridated water.
Fluoride in toothpaste also helps in preventing tooth decay. In the United States, toothpaste typically contains 1,000 to 1,100 ppm fluoride, whereas concentrations in some European countries can be higher. The additional fluoride in products helps to form fluorapatite, making dental enamel more resistant to decay. However, an excessive amount of fluoride, especially from natural water sources, is the primary cause of fluorosis.