Abstract

1.  Round-the-clock exposure to hydrogen fluoride concentrations of 0.10 and 0.03 mg/m3 causes inhibition in the central nervous system, decreases the activity of a number of enzymes, impairs the phosphorus-calcium metabolism, and causes the accumulation of fluorine in the body and damage to the internal organs and bone tissue.

2.  A hydrogen fluoride concentration of 0.01 mg/m3 should be regarded as the threshold concentration. Its effects on the body of the animals showed changes in the phosphorus metabolism only (inhibition of alkaline blood phosphatase and a delayed inclusion of radiophosphorus in bone tissue, liver, and blood at the end of a five-month exposure of the animals).

3.  The mean daily maximum permissible concentration of hydrogen fluoride in the air of populated areas, adopted earlier as 0.01 mg/m3, should be lowered to 0.05 mg/m3.

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