In vitro studies ... indicated that THF was first hydroxylated by the microsomal enzymes and further cleaved to the straight chain fatty acid in the presence of cytosol.
HUMAN TOXICITY: Data pertaining to the toxicity of tetrahydrofuran (THF) in humans is quite limited. The probable oral lethal dose in humans is 50-500 mg/kg. Severe occipital headaches were reported in the testing for pharmacological properties of THF & among technicians performing animal experiments. Toxicity (TCLo) is expected following exposure to a 2.5% concn of THF. ANIMAL TOXICITY: Animal studies indicate that THF is only "MODERATELY TOXIC" from acute exposure with the lowest reported LD50's of 1900-2900 mg/kg by oral route. Median lethal concns by inhalation varied with the duration of exposure but were >20,000 ppm with all species for exposures of 1 hr or less. Reports of animal studies document irritation of the skin & mucous membranes, including the eyes, nose, & upper respiratory tract, as the predominant effect from lower exposures (about 100-200 ppm). High acute doses (about 25,000 ppm) produced anesthesia with delayed induction & recovery periods, accompanied by a fall in blood pressure & strong respiratory stimulation. The margin of safety between anesthesia & death is small. Other effects recorded are those of damage to liver, kidneys, & lung after prolonged exposures to levels of THF >1000 ppm. Toxic manifestations varied somewhat with the route of exposure with irritation of upper respiratory tract observed with inhaled THF & inflammation of the GI tract following oral ingestion. The only report on carcinogenicity is that of a test for skin tumors in which THF was applied to the skin of mice twice/wk for 25 exposures with an observation period of 17.5 months. No carcinogenic effect was observed. THF was negative when tested for mutagenicity using the Ames test; however, it would appear to enhance the mutagenicity of certain tryptophan-pyrolysate substances. No information is presented on metabolism, absorption, & distribution. The only report on excretion is the finding of THF in mother's milk.
来源:Hazardous Substances Data Bank (HSDB)
毒理性
致癌性证据
A3; 已确认的动物致癌物,对人类的相关性未知。
A3; Confirmed animal carcinogen with unknown relevance to humans.
THF levels in various organs as well as excretion rates were determined in three different inhalation experiments in rats: 1) 30 min exposure to 45 mg/L (15,000 ppm); 2) 30 min/day, 7 day exposure to 45 mg/L (15,000 ppm); 3) 1 hr/day, 5 days/week, 12 weeks exposure to 9 mg/L (3000 ppm). Results: 1) Immediately after the completion of the exposure the following order of THF concentrations were seen: blood > brain > kidneys > heart > liver > spleen > lung. The lowest concentration was in the lung: 200 mg/kg, in the other organs: 480-600 mg/kg (maximum excretion in exhaled air). After 1 hr 70-80% had been excreted from the organs; the remainder slowly disappeared over 12-13 hr. 2) Directly after the final exposure, the lowest value was 130-300 ug/kg as in the single exposure. Excretion in the initial phase was weaker with higher THF concentrations after 1 or 3 hr. After 6 hr the excretion rate was similar to the single exposure study. 3) Directly after the last exposure the highest THF concentration was in the thymus (160 ug/kg) and spleen (110 ug/kg), 60-100 ug/kg in the other organs. The thymus also had the highest concentration of the organs after 6 hr; the concentrations in the lungs and other organs were similar (an indication of reduced exhaled excretion); complete excretion of THF was in about 12 hr as in 1) and 2). Conclusion: tissue levels are dependent on THF-concentrations in exhaled air. Greatest excretion occurs in exhaled air. /Translated from German/
A single oral application of 300 mg/kg THF as a 10% aqueous solution was given to rats (strain and sex not given). The animals were killed 10-300 min following application and the THF concentration in liver, kidneys, brain, spleen, muscle, adipose tissue, and blood determined (gel column, mass spectroscopy). The highest THF value in the blood was at 1 hr post-application (about 200 mg/kg). The biological half-life in blood was 5 hr. THF concentrations in adipose tissue and kidneys were 1.3-1.4 times higher than in blood; levels in liver, brain, spleen, and muscle were similar to blood. Comparable levels were found in two rabbits after oral application of 700 mg/kg (half-life 4-6 hr; THF(adipose tissue)/THF(blood) ratio 1.4, ratio for remaining organs 0.5-0.9). In a second experiment with rats, 300 mg/kg doses were again used. THF concentration in blood was measured over 24 hr. It climbed rapidly to a maximum of 150 mg/kg 1.5-2 hr post-application; thereafter it declined gradually to null over 24 hr. Biological half-life in blood: 7.5 hr. /Translated from German/
Adult male rats exposed to tetrahydrofuran vapor at 8.2 (200 ppm), 41 (1,000 ppm) or 82 mumol/l (2,000 ppm) for 2 to 18 weeks, five days a week, 6 hrs daily, showed dose-dependent brain and perirenal fat solvent burden linearly correlated to each other. After two weeks of exposure, the body burden of tetrahydrofuran seems to decrease. This might have been caused by increased oxidative metabolism as enhanced 7-ethoxycoumarin-O-deethylase activity was detected in liver and kidneys in the second week and onwards. The exposure also caused inhibition of alcohol and formaldehyde dehydrogenase activities in liver at the highest dose. Biochemical effects in the cerebellum were not detected, while gluteal muscle specimens showed increased succinate dehydrogenase activity in a dose-related manner. This points to effects on the energy metabolism. Muscle acetylcholine esterase activity was also increased showing possible effects on the myoneural junctions.