306 Chronic Fluorine Intoxication in Domestic Animals.
20 to 50 per cent more fluorine per unit weight than compact bones (85,
101).
While different animals consuming the same diet vary in their capacity
to store fluorine, the greater proportion of the fluorine which is retained ap-
pears to be laid down in the bones. The long latent period, a year or more in
herbivora, during which the animal suffers no apparent untoward effects
while steadily ingesting each day an amount of fluorine which eventually
proves seriously toxic, may no doubt be explained by a gradual saturation
of the skeleton until a stage is reached when its buffering effect is no longer
capable of immobilising the greater part of the absorbed fluorine, which is
then free to exert general toxic effects (85, 92, 93, 111, 115).
There is no general agreement as to the influence of continual ingestion
of small amounts of fluorine on the actual percentage of ash in the bones
and the teeth. Some investigators have detected no change (11, 53, 60, 68),
others have suggested an increase (55, 85), and some an actual decrease (46).
An increase in the percentage of magnesium and a decrease in the carbon
dioxide in the bones has been reported (68), the latter apparently being due
to the conversion of the carbonate-apatite of the bone substance to fluora-
patite.
The fluorine content of the other organs increases also after continual
ingestion of materials containing fluorine. The fluorine concentration in
the tissues of hens and cows has been reported to increase from two to five
times over that found in normal tissues, which is usually between 0.5 and 1 mg.
fluorine per 100 g. dry matter (13, 54). The thyroid of a cow has been report-
ed to contain 160 mg. fluorine per 100 g., two hundred and forty times the
amount found in normal animals (13). The fluorine content of the blood of
cows has been reported to increase from 0.2 to 0.6 mg. per 100 ml. as a result
of fluorine feeding (37), and a similar increase from 0 to 0. 15 mg. per 100 ml.
has been described in hens under similar conditions (94). Eggs-produced
by hens receiving abnormal amounts of fluorine in their diet have been reported
to contain from 0.05 to 0.2 mg. per 100 g. (89, 94), most of it being concen-
trated in the lipoid fraction of the yolk (89). The milk of cows ingesting re-
latively large quantities of fluorine has been found by one observer (91) to
be normal and by another (63) to contain an abnormal amount of fluorine.
Atrophy of the spongiousa, defective and irregular calcification of the
newly formed osseous tissue, and active periosteal bone formation, which
is considered to resemble the histological picture of osteomalacia, has been
described in the bones of pigs, of cattle and of sheep suffering from the chronic
effects of ingestion of fluorine (68, 73, 92, 101). Hypoplasia of both the enamel
and the dentine of the teeth of cattle (92) and of pigs (68, 101) has been des-
cribed. Changes of a degenerative type have frequently been reported in
the kidneys (68, 92, 101, 107) and in the livers (82, 92, 101, 119) of pigs, cattle
and sheep, and in the suprarenals, heart muscle and central nervous system
of cattle (92, 101).
Other effects of fluorine poisoning which have been described are reduced
milk production in cows and goats (15, 64, 92, 95), and reduced egg produc-
tion in poultry (12, '60, 94). These, no doubt are correlated with lessened
food consumption. Diuresis (68, 101) and increased water consumption
(44, 68, 82, 101) have been observed to occur in pigs, and diarrhœa is a