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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Studies on sural nerve biopsies in endemic skeletal fluorosis
Sural nerve biopsies from 13 patients with radiologically confirmed skeletal fluorosis were studied for myelinated fibre densities, frequency distribution oftheir diameters, and single teased nerve fibre preparations. It was observed that most of the biopsies showed a marked reduction in myelinated fibre densities with more than half of them in:volving
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Effects of fluorine on the human fetus.
In an endemic fluorosis area, 16 fetuses that were delivered during their sixth to eighth month of gestation by means of artificial abortion were collected and studied. The results [compared to 10 control fetuses from a non-endemic area] show that fluorine levels in tissues are obviously high, especially in brain, calvarium, and femur. The activity of alkaline
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Studies on skeletal muscle biopsies in endemic skeletal fluorosis
Neurological manifestations of skeletal fluorosis have been attributed to compressive radiculomyelopathy. Experimental fluorosis has shown evidence of myopathic changes. Data on human muscle pathology is very scanty. This study included 22 patients with established osteofluorosis. 16 of them showed only EMG changes of neurogenic muscle disease. Histochemistry and histopathology of muscle biopsies showed
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Developmental toxicity of sodium fluoride in rats
Despite the chronic exposure of the US population to fluoridated drinking water since the 1940s, existing studies have been judged inadequate to determine any potential reproductive or developmental hazard. This study was conducted to determine the effects of sodium fluoride (NaF) on foetal development. Sperm-positive female rats were given 0,
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Effects of fluoride exposure on performance in water labyrinth and monoamine neurotransmitters of rats
Objective To study the effects of fluoride exposure on performance in water labyrinth and monoamine neurotransmitters of rats. Methods Forty SD rats were divided randomly into 4 groups:control group,high-fluoride exposed group,medium-fluoride exposed group and low fluoride exposed group.These 4 groups of rats were exposed to different concentrations (0,5,10,20 mg/kg) of sodium
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"Pre-Skeletal" Fluorosis
As demonstrated by the studies below, skeletal fluorosis may produce adverse symptoms, including arthritic pains, clinical osteoarthritis, gastrointestinal disturbances, and bone fragility, before the classic bone change of fluorosis (i.e., osteosclerosis in the spine and pelvis) is detectable by x-ray. Relying on x-rays, therefore, to diagnosis skeletal fluorosis will invariably fail to protect those individuals who are suffering from the pre-skeletal phase of the disease. Moreover, some individuals with clinical skeletal fluorosis will not develop an increase in bone density, let alone osteosclerosis, of the spine. Thus, relying on unusual increases in spinal bone density will under-detect the rate of skeletal fluoride poisoning in a population.
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