Fluoride added to drinking water through a process called fluoridation can increase risk of bone cancer in boys, according to a Harvard study published in 2006 in Cancer Causes & Control.
The study led by Elise B. Bassin at Harvard School of Dental Medicine and colleagues from other organizations shows a positive link between exposure to fluoride in drinking water under the age of seven years and bone cancer risk. And higher exposure was linked higher risk for bone cancer in boys.
The potential risk was not as consistent or as significant in girls though.
The study analyzed data from a study of 103 cases of bone cancer and 215 matched controls performed through 11 U.S. hospitals. The exposure to fluoride was estimated based on the type of drinking water and climate conditions. Cases and controls were aged younger than 20 years old.
For the study, three levels of fluoride exposure were defined, including low (30% of the CDC targeted level of fluoridation), medium (30 to 90% of the CDC targeted level) and high (> 99% of the CDC targeted level).
The risk of bone cancer was significantly elevated in those with higher exposure to fluoride as the age increased. The highest risk which was four times as high as that for those who were not exposed to higher levels of fluoride was observed in boys and girls at the age of seven years.
After adjustment for confounders, the risk for boys at the age of seven years to develop bone cancer remained consistent and was 5.46 times as high as that in those who were not exposed to high levels of fluoride.
The association was not as apparent among females.
The authors conclude that fluoride exposure in drinking water during childhood was associated with a significantly elevated risk of bone cancer in boys.
Fluoride is added (a process called fluoridation) in more than 75% of the U.S. public water system. At this moment, the U.S. Environmental Protection Agency set the recommended level at 1 ppm. There is some variation from one city to another. The early recommended level was higher.
Dentists who advocate the fluoridation movement claim that exposure to low levels of fluoride can help prevent dental caries. But over-exposure to the toxic chemical, which is known to lower IQ in children, can cause even more serious dental fluorosis and even skeletal fluorosis. Fluoride is harmful to neurons and bone cells to say the least.