The Effects of Ingesting Too Much Fluoride

Found naturally in your body as calcium fluoride, fluoride helps prevent cavities and helps develop strong, healthy teeth. Adult men need 4 milligrams of fluoride per day, whereas adult women require 3 milligrams, according to the University of Maryland Medical Center. Ingesting more than the recommended amounts of fluoride from dietary, as well as from environmental sources can pose a threat to your health. Common sources of fluoride include dental products, processed foods made with fluoridated water, fluorinated pharmaceuticals, fluoride-containing pesticides, bottled tea, mechanically deboned chicken and nonstick pans.

A mother and daughter in the bathroom in their pajamas prepare to brush their teeth. (Image: XiXinXing/XiXinXing/Getty Images)

Dental Fluorosis

Consuming too much fluoride in early childhood when teeth are developing under the gums can lead to dental fluorosis. This condition is characterized by failure of tooth enamel to crystallize properly leading to defects such as brittleness, staining that is barely noticeable to severe brown stains and surface pitting. The severity of dental fluorosis depends on factors such as the dose, timing and duration of fluoride consumption. Children aged 0 to 8 years are at risk for developing dental fluorosis, because this is when permanent teeth begin to form under the gums. For better dental health, the United States Public Health Service has set the amount of fluoride in drinking water between 0.7 and 1.2 milligrams per liter.

Kidney Toxicity

Renal excretion is the main elimination route for inorganic fluoride from your body. As a consequence, the cells of your kidney are exposed to relatively high concentrations of fluoride, making your kidneys vulnerable to fluoride toxicity. According to the Subcommittee on Health Effects of Ingested Fluoride of the National Research Council, animal studies have demonstrated that exposure to fluoride at concentrations of 100 to 380 milligrams per liter of drinking water can cause swelling in between the kidney tubules, dilation of renal tubules and death of proximal and renal tubules.

Gastrointestinal Side Effects

Fluoride and hydrogen ions can bind together to form hydrogen fluoride in the acid environment of your stomach. High concentrations of hydrogen fluoride may damage your stomach. The subcommittee notes that studies of workers exposed to fluctuating levels of fluoride in the workplace have disclosed a wide array of gastrointestinal side effects. These include erosion of the mucosal lining of the stomach, duodenal ulcers and long-term inflammation of the stomach lining with or without accompanying skeletal fluorosis -- a bone disease caused by excessive intake of fluoride. However, due to lack of availability of fluoride measurements, actual exposure concentrations of the mineral are not known but are speculated to be high.

Other Health Risks

A meta-analysis of 27 studies linked fluoride ingestion to I.Q. deficits in children, notes the Fluoride Action Network. Three studies from China have discovered that the increased intake of fluoride during pregnancy can harm the fetal brain. Animal and human research show that ingesting excess fluoride aggravates the effects of iodine deficiency. Iodine is essential for proper thyroid function. Inadequate intake of iodine during infancy and early childhood can lead to permanent brain damage, including mental retardation.