TABLE I
Showing Relation of Fluoride to Incidence of Mottled Enamel in Children

		Composite of 9, 10, and 11 Year Old Children
City and State	Fluoride Content in p.p.m.	Number of Children Examined	Incidence per 100 Children
Junction City, Kans.	0.7	115	1.7
East Moline, Ill.	1.5	110	24.5
Webster City, Iowa	1.6	72	26.4
Clovis, N. M	2.2	138	71.0
Plainview, Tex.	2.9	77	87.0
Amarillo, Tex.	3.9	229	89.5
Conway, S. C.	4.0	59	88.1
Lubbock, Tex.	4.4	164	97.6

In Table I, taken from report by
Dean and Elvove,²⁷ are shown data for
the incidence of mottled enamel in children
correlated with the fluoride content
of waters from widely separated
cities in the United States.

… In Figure I is shown the distribution
of areas known to have mottled
enamel and in most cases the
waters are known to contain excessive
fluorides.

… In Figure II a relief map of the
United States shows the general geologic
conditions. Note the Piedmont
areas adjacent to the igneous protrusions
into which drainage water from
igneous formation percolates. The
presence of mottled enamel in areas
adjacent to Mt. Vesuvius in Italy appears
to have been associated with
waters which had their origin on the
laval surfaces of that volcano.

…In Table II are given results showing
that there were only 40 rocks of the
172 that contained more than the
average amount of fluorine and that of
these there were only 8 which contained
the element in amounts above 1.0 per
cent. Fluorine was found in not only
many different kinds of rocks but it
was also rather evenly distributed
among the various classes of igneous
rocks. The occurrence of fluorides in
sedimentary formations seems to be
still more erratic than that in primitive
rocks.

… Fluorapatite, Ca5 (P04)sF, is another
mineral which may be responsible
for the presence of fluorides in natural
waters, as it is a rather common constituent
of all classes of rocks-igneous,
metamorphic, and sedimentary, and
forms the source of fluorine in the
phosphate rock deposits of Florida,
Tennessee, Virginia, Idaho, and Montana.
The fluorine content of these
materials varies from practically zero to
4 per cent, and the presence of this
element in these products, which are
used both for fertilizer, as a supplementary
mineral in stock feeding, and
as a source of phosphate in baiting
powders, has occasioned much experimentation
on the· physiological effect of
fluorine on both animal and plant life.