<P> The U.S. Centers for Disease Control found a 9 percentage point increase in the prevalence of confirmed dental fluorosis in a 1999 - 2002 study of American children and adolescents than was found in a similar survey from 1986 - 1987 (from 22.8% in 1986 - 1987 to 32% in 1999 - 2002). In addition, the survey provides further evidence that African Americans suffer from higher rates of fluorosis than Caucasian Americans . </P> <P> The condition is more prevalent in rural areas where drinking water is derived from shallow wells or hand pumps . It is also more likely to occur in areas where the drinking water has a fluoride content greater than 1 ppm (part per million). </P> <Table> Dietary reference intakes for fluoride <Tr> <Th> Age group </Th> <Th> Reference weight kg (lb) </Th> <Th> Adequate intake (mg / day) </Th> <Th> Tolerable upper intake (mg / day) </Th> </Tr> <Tr> <Td> Infants 0--6 months </Td> <Td> 7 (16) </Td> <Td> 0.01 </Td> <Td> 0.7 </Td> </Tr> <Tr> <Td> Infants 7--12 months </Td> <Td> 9 (20) </Td> <Td> 0.5 </Td> <Td> 0.9 </Td> </Tr> <Tr> <Td> Children 1--3 years </Td> <Td> 13 (29) </Td> <Td> 0.7 </Td> <Td> 1.3 </Td> </Tr> <Tr> <Td> Children 4--8 years </Td> <Td> 22 (48) </Td> <Td> 1.0 </Td> <Td> 2.2 </Td> </Tr> <Tr> <Td> Children 9--13 years </Td> <Td> 40 (88) </Td> <Td> 2.0 </Td> <Td> 10 </Td> </Tr> <Tr> <Td> Boys 14--18 years </Td> <Td> 64 <P> (142) </P> </Td> <Td> 3.0 </Td> <Td> 10 </Td> </Tr> <Tr> <Td> Girls 14--18 years </Td> <Td> 57 (125) </Td> <Td> 3.0 </Td> <Td> 10 </Td> </Tr> <Tr> <Td> Males 19 years and over </Td> <Td> 76 (166) </Td> <Td> 4.0 </Td> <Td> 10 </Td> </Tr> <Tr> <Td> Females 19 years and over </Td> <Td> 61 (133) </Td> <Td> 3.0 </Td> <Td> 10 </Td> </Tr> </Table> <Tr> <Th> Age group </Th> <Th> Reference weight kg (lb) </Th> <Th> Adequate intake (mg / day) </Th> <Th> Tolerable upper intake (mg / day) </Th> </Tr>

Excessive ingestion of fluoride during the time of tooth formation