This study was based on the total intake of children in
the real world. There was no intervention, just a look at what the kids got from toothpaste, supplements, and water. (The
graph is on all sources.) The study was in Iowa on about 1300 normal Midwestern children. (Timing wise, this study ran from
1992-95, so mostly before the May 1995 new schedule from the AAP.*)
My take on this is that the average children (50th percentile
line) are pretty close to what we would like to see.
(And this makes sense, as the recommendations most are
following are based on the average child. The stated optimum intake from the AAP and most other sources is still .05 mg/kg.
I think that dosage is fine, but a little dated as an optimum. I use .033 mg/kg and that is the line I put on the graph.)
at the lower percentiles, the 10th and 25th. These children, especially in first year, are very, very low in fluoride. They
are probably at or near a negative fluoride balance** much of the time.
Graph data: Levy, SM 2001, unpublished data from the Iowa
Fluoride Study. firstname.lastname@example.org
See also Levy SM et al. Patterns of Fluoride Intake from
Birth to 36 Months. J Pub Health Dent 2001. 61(2):70-7.
* Since the 1995 AAP schedule change, even more infants
will be too low. The major change is dropping all fluoride supplements under age 6 months. At the time of the study, roughly
40% of the USA did not have fluoridated water, and if not infants were scheduled to get a .25 mg F supplement. That dose to
a 5 kg (11 pound) infant is .05 mg/kg, which is where the 50th percentile is on the graph above, from about 3-10
months. Now many of these kids that were fine will drop into the negative fluoride balance zone.
** The line
on the graph for the threshold of negative fluoride balance is just a guess. I'll get a graph up one day to show the guesswork.
Basically you can say for sure that below an intake of about .005 mg/kg an infant will be losing fluoride. Then there is a
lack of data until you get into the optimum zone. My guess is that if you can give an infant .011 mg/kg, odds are about 90%
the infant will be gaining fluoride or at least staying even.