A. W. PEIRCE.
305
EXPERIMENTAL OBSERVATIONS ON POISONING BY FLUORINE
The effects of continual ingestion of fluorine from a variety of sources
have been investigated in cattle (13, 36, 37, 39,76, 87, 91, 92, 93, 95, 101, 112)
in sheep (85, 99, 113) in goats, (15) in pigs, 2, 3, 4, 44, 46 55, 56, 68, 70, 82,
101, 113, 120) and in poultry (11, 12, 53, 54, 60, 67, 68, 88, 89, 94).
In all experiments the animals seem to have suffered from reduced ap-
petite and less efficient utilisation of food when the ingestion of sublethal
amounts of fluorine was continued. This results in less rapid growth in the
young and loss of weight in mature animals. Unthriftiness anorexia and
death follow the ingestion of relatively large amounts of fluorine. Specific
chemical and morphological changes are manifested in the bones and in the
teeth. The normal ivory colour of the bones becomes changed to a chalky
white, and the diameter of the cross section of the long bones is increased, due
in part to an enlargement of the marrow cavity, but mainly to an increase
in the thickness of the bone substance. Exostoses of the long bones and of
the jaws are a common feature. These take the form either of isolated out-
growths or of a complete superficial covering of porous white bone of high
fluorine content. The changes in the mandibles of sheep and cattle are readily
detected by palpation. In pigs, the width of the dental arch is increased
(68). The bones of animals given fluorine are, as a rule, much softer than
normal (3, 4, 46, 53, 68, 82, 101, 103) but owing to overgrowth the breaking
strength of the whole borne may be increased (92). The teeth particularly
the incisors, become pitted and eroded. The molars become abraided and
the uneven wear seriously hinders mastication. In some cases the pulp
cavities are exposed (68, 92) and this leads to reluctance by the affected
animals to drink cold water (68, 92, 95, 111). Few, if any, dental changes
occur if the teeth have been fully developed prior to the ingestion of fluorine,
although bone changes may be induced at any age (85).
The fluorine content of the bones and teeth increases in proportion to
the amount and duration of the intake. Since most food stuffs contain
traces of fluorine, all animal bones which have been examined have been
found to contain this element. While the amount of fluorine immobilised
in this way increases with the age of animal (38, 42, 50), the concentration
found in normal bones' is generally between 0.01 and 0.15 per cent
of the bone ash (7, 13, 18, 48, 50, 54, 68, 69, 85, 101, 102). This is slightly
more than is found in the ash of whole teeth (13, 68, 85, 91, 102), the dentine
of which contains more than is found in the enamel (13, 101). Ingestion of
quantities of fluorine which apparently exert no untoward effects on the
general health of the animal or which bring about no obvious morphological
change in its skeleton, may, nevertheless, increase ten to fifteenfold the fluorine
content of the bones and teeth (13, 54, 68, 85). Intakes sufficiently large to
bring about general toxic effects may enhance the fluorine concentration in
the bones and teeth from fifteen to thirty times that of normal (13, 54, 68,
85) and occasionally as much as seventy times the normal fluorine content
has been observed in these organs (101). Under such conditions the bone
ash may contain up to 2 per cent of fluorine and the ash of the teeth approxi-
mately half this amount. The highest concentrations of fluorine occur in
the exostoses which contain up to 2.7 per cent; the epiphyses contain less
and the compact shaft least of all (85). Cancellous bones may contain from
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