Fluorinated toxicity

While the soil-io-plam segment of ihe fond chain contains some built-in safeguards against fluorine loxicily. this loxicily occurs as a result nf Ihe deposition of airborne fumes and dusts on the above-ground parts of plants, followed hy ihe consumption of these contaminated plants by animals, including humans. Also, fluorine toxicity hits been caused hy direct inhalation of the fumes and dusts, or hy drinking water with abnormally high fluorine levels. If the fumes and dusts anc mixed into the soil, they wilt be inactivated, and they will nol find their way into the food chain in toxic amounls. 

A few other fluorinated kanamycins, including 5-deoxy-5-epi-fluoroamikacin, 5-deoxy-5-ep(-fluoroarbekacin, and their related analogs, have been prepared to study the fluorination-toxicity relationship. In contrast to the low toxicities of the 5-fluoro derivatives [121], these epi-fluoro compounds showed acute toxicity values identical to those of arbekacin and amikacin [122]. This indicates the importance of stereo-electronic effects of the fluoro group at position 5 of the 2-deoxystreptomine moiety in toxicity of aminoglycoside antibiotics. 

In a study on the fluorination-toxicity relationship, investigators prepared 1-A-acylamido derivatives of kanamycins, including (2R,3R)- and (27 ,35)-4-amino-3-fluoro-2-hydroxybutanoylkanamycins A and B (compounds 262-265 ). The l-N-[(2/ ,3i )-4-amino-3-fluoro-2-hydroxybutanoyl] derivatives 262-264 showed activity similar to that of the related compoimds [amikacin (2), arbekacin (260), and l-N-[(5)-4-amino-2-hydroxybutanoyl]-3 -deoxykanamycin B 261], whereas the (2R,3S)-derivative 265 (compounds 260 65) showed decreased activity relative to 260. In toxicity, these compounds were similar to the parent antibiotics, and fluorination did not show any influence in the toxicity of the antibiotics [137]. 

Absorption, Metabolism, Excretion Functions of Fluorine Deficiency Symptoms Interrelationships Recommended Daily Allowance of Fluorine Toxicity... 

Elemental fluorine and the fluoride ion are highly toxic. The free element has a characteristic pungent odor, detectable in concentrations as low as 20 ppb, which is below the safe working level. The recommended maximum allowable concentration for a daily 8-hour time-weighted exposure is 1 ppm. 

Toxicity. Fluorine is extremely corrosive and irritating to the skin. Inhalation at even low concentrations irritates the respiratory tract at high concentrations fluorine inhalation may result in severe lung congestion. 

Toxicity studies (108—110) estabUshed tolerance levels and degrees of irritations, indicating that the eye is the area most sensitive to fluorine. Comprehensive animal studies (111—113) deterrnined a rat LC q value of 3500 ppm-min for a single 5-min exposure and of 5850 ppm-min for a 15-min exposure. A no-effect concentration corresponded to a concentration-time value of ca 15% of the LC q levels. 

Because of the corrosive effects and discomfort associated with inhalation of fluorine, chronic toxicity does not occur. Although the metaboHc fate of fluorine is not clear, it does not seem that much is converted to fluoride ion in the body (107). Therefore comparisons to effects of fluoride ion poisoning, known as fluorosis, are probably incorrect. 

Lead fluorides are highly toxic and should be handled with great care. The ACGIH adopted toxicity value for lead compounds as Pb is TWA 0.15 mg/m and for fluorides as F 2.5 mg/m. PbF is prepared by the action of elemental fluorine on very dry Pbp2 at 280—300°C (15). 

Health and Safety Factors. Completely fluorinated alkanes are essentially nontoxic (16). Rats exposed for four hours to 80% perfluorocyclobutane and 20% oxygen showed only slight effects on respiration, but no pathological changes in organs. However, some fluorochemicals, especially functionalized derivatives and fluoroolefins, can be lethal. Monofluoroacetic acid and perfluoroisobutylene [382-21-8] are notoriously toxic (16). 

Health and Safety Factors. The toxicity of aHphatic CFCs and HCFCs generally decreases as the number of fluorine atoms increases (16), as shown in Table 7, but there are exceptions as in the case of 141b vs 142b. Also, some derivatives like HCFC-132b can have low acute but high chronic toxicides (29). 

Health and Safety Factors. Fluorocarbons containing bromine or iodine are more toxic than the corresponding chloro compounds. When the ratio of the fluorine to other halogens is high, the toxicity can be quite low, especially for bromofluorocarbons. Perfluoro-l-bromooctane [423-55-2] has an LD q of greater than 64 mL/kg when adininistered into the gastrointestinal tract, and has Htde effect when instilled into the lungs (49). Other examples are included in Table 7. 

F. L. M. Pattison, Toxic Aliphatic Fluorine Compounds, Elsevier Publishing Co., New York, 1959, p. 16. 

Pentafluorobenzene. Pentafluoroben2ene has been prepared by several routes multistage saturation—rearomati2ation process based on fluorination of ben2ene with cobalt trifluoride reductive dechlorination of chloropentafluoroben2ene with 10% pabadium-on-carbon in 82% yield (226,227) and oxidation of penta uorophenylbydra2ine in aqueous copper sulfate at 80°C in 77% yield (228). Its ioni2ation potential is 9.37 V. One measure of toxicity is LD q = 710 mg/kg (oral, mouse) (127). 

Because PTFE resins decompose slowly, they may be heated to a high temperature. The toxicity of the pyrolysis products warrants care where exposure of personnel is likely to occur (120). Above 230°C decomposition rates become measurable (0.0001% per hour). Small amounts of toxic perfiuoroisobutylene have been isolated at 400°C and above free fluorine has never been found. Above 690°C the decomposition products bum but do not support combustion if the heat is removed. Combustion products consist primarily of carbon dioxide, carbon tetrafluoride, and small quantities of toxic and corrosive hydrogen fluoride. The PTFE resins are nonflammable and do not propagate flame. 

Rotenoids. The use of rotenone-bearing roots as insecticides in the United States was developed as a result of federal laws against residues of lead, arsenic, and fluorine upon edible produce. Rotenone [83-79-4] (5) is harmless to plants, highly toxic to many insects, and relatively innocuous to... 

Under unusual circumstances, toxicity may arise from ingestion of excess amounts of minerals. This is uncommon except in the cases of fluorine, molybdenum, selenium, copper, iron, vanadium, and arsenic. Toxicosis may also result from exposure to industrial compounds containing various chemical forms of some of the minerals. Aspects of toxicity of essential elements have been pubhshed (161). 

Chemical Hazards. Chemical manufacturers and employees contend with various ha2ards inherent ia productioa of evea commonplace materials. For example, some catalysts used ia the manufacture of polyethylene (see Olefin polymers) ignite when exposed to air or explode if allowed to become too warm the basic ingredient ia fluorocarboa polymers, eg, Tefloa (see Fluorine compounds, organic), can become violently self-reactive if overheated or contaminated with caustic substances (45,46) one of the raw materials for the manufacture of acryflc fibers (see Fibers, acrylic) is the highly toxic hydrogen cyanide (see Cyanides). 

Polytetrafluoroethylene decomposition products thermal decomposition of the fluorocarbon chain in air leads to the formation of oxidized products containing carbon, fluorine and oxygen. Because these products decompose in part by hydrolysis in alkaline solution, they can be quantitatively determined in air as fluoride to provide an index of exposure. No TLV is recommended pending determination of the toxicity of the products, but air concentration should be minimal. (Trade names Algoflon, Fluon, Teflon, Tetran.)... 

Halogenation The commercially important halogens are chlorine, bromine, fluorine, iodine. Refer to Table 5.19 for properties All are highly toxic Reactions are highly exothermic and chain reactions can occur, which may result in detonation... 

Flammability (e.g. hydrogen, acetylene, methane), toxicity (e.g. carbon dioxide, fluorine), or chemical reactivity (fluorine, oxygen). 

A special precaution is imperative in handling elemental fluorine and chlorine tnfluoride. Both gases are extremely corrosive and so reactive that they are very seldom used without dilution with inert gases such as nitrogen, helium, or argon. Fluorine is now available in mixtures with nitrogen. Fluorine is very toxic in... 

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