The American College of Veterinary Toxicologists of the American Veterinary Medical 
Association is just finishing a color film strip with a documented descriptive narration 
on ‘‘A Study of Chronic Fluorosis in Livestock."* This film was prepared with the assist- 
ance of many States, countries, and industrial companies that have conducted and fi- 
manced research on the subject. Huffman (1952) and later Binns (1956) summarized 
the principal problems of industrial fluorine contaminations of livestock feeds. 
Chronic fluorosis develops in farm animals receiving more than a minute amount of 
fluorine for a long time. The minimal amount of fluorine in the form of soluble fluorides 
required to produce injury in cattle and other farm animals lies between 1 and 2 mg./kg. 
body weight daily. The effect on a given animal depends on the species, the amount of 
fluorine ingested, the age during ingestion, the form of fluorine in the feed, and such 
stress factors as nutritional balance. All these factors must be considered in evaluating 
the effect of fluoride on an animal. Thus it is difficult to state the exact degree of herbage 
contamination that is significant. Contamination of pasture plants with industrial fumes 
and dusts to the extent of 25 to 50 p.p.m. on a dry-matter basis is generally considered 
to be potentially dangerous to grazing animals (Garner, 1957). However, ina 6-year 
study on a controlled experiment with healthy cattle on adequate calcium, phosphorus, 
protein, and vitamins, a total intake of 60 parts per million of sodium fluoride was 
required to produce definite chronic fluorosis (Newell and Schmidt, 1958). Other workers 
have classified the effects of ingestion of fluorine according to reduced feed consumption, 
failure to grow, loss in weight, loweredmilk production, lowered reproduction, lameness, 
bone exostoses, fluorine content of bone, blood studies, urine fluorine, and teeth changes. 
The p.p.m. ingested have been correlated with these changes (Hobbs, et al, 1954). An 
increased intake of fluorine, environmental or experimental, results in a progression of 
dental effects. The changes from minor to severe effects in dental fluorosis are chalki- 
ness of the enamel staining of the caries and erosion of the enamel, hypoplasia of the 
enamel, and hypoplasia of the teeth. These have all been excellently demonstrated in 
color plates by Hobbs, et al. (1954). Inthis work, it took about 2-1/2 years for cows on 50 
p-pem. fluorine to show reduced feed consumption and 18 months for cows on 70 p.p.m. 
This definite proof of the long time required to show illness and the detrimental effects 
of the prolonged feeding of small amounts of fluorides emphasize the need for much 
toxicological research on farm animals for effects of some chemicals in their feed. 
Fluorides are emitted in various processes such as the manufacture of aluminum, 
steel, phosphate fertilizer, bricks, pottery, ferroenamel; also, in the calcining of iron 
ore where the source is mainly the fluorine-rich ore itself, from fused tricalcium phos- 
phate furnaces, and from the burning of some coal. The troubles from fluorine effluents 
from steel plants and metal works usually have been when large amounts of the fluospar 
in the flux are used, The stack gases from phosphate fertilizer plants contain considerable 
quantities of fluorides. It is more difficult to control the emanations from phosphate 
fertilizer plants than from aluminum reduction plants. 
Hay and forage crops may be contaminated from phosphatic dusts or from air-borne 
industrial effluents not properly controlled. Phosphatic soils may contain 50,000 p.p.m. 
and raw rock phosphate may be a constitutent of feed supplements. Hydrogen fluoride and 
fluorine are important air contaminants even in their extremely low concentrations of 
0.001 to 0.10 p.p.m. by volume because they accumulate in the leaves of plants and can 
be absorbed in forage and hay to such an extent as to cause fluorosis in animals (Katz, 
1956). Concentration values are lower than those of virtually all other pollutants, which 
may occur in the atmosphere from industrial activities; the various fluorides dispersed 
as aerosols have received considerable and particular attention because of the poisoning 
from such small amounts if consumed for a long time. Rupp (1956) reported the maximal 
permissible concentration of hydrogen fluoride for industrial operations is 3 p.p.m. 
Ferguson (1960) reports that industry as a whole is working very hard to clean up their 
atmospheric effluents. One aluminum reduction plant in particular has already spent in 
excess of $2-1/2 million in this particular field. 
The fluorine content of any mineral or mineral mixture that is to be used directly for 
feeding of domestic animals shall not exceed 0.3 percent for cattle; 0.35 percent for 
sheep; 0.45 percent for swine and 0.6 percent for poultry. These limits have been set by 
the Association of American Feed Control Officials (Maynard and Loosli, 1956). 
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