Document da3d0OkGaNkrXZ2Oo0K7xan46

Elements of Industrial Toxicology tivity were observed Gasoline vanes in composition, but is commonly a petroleum fraction containing hexanes, heptanes, and octanes with varying amounts of unsaturated, cyclic, and aromatic compounds A cracked gasoline may con tain 50 per cent or more compounds other than the saturated aliphatic hvdrocarhons If the gasoline consists of saturated and unsaturated aliphatic compounds and cyclic compounds it will be a narcotic and an ir ritant to the mucous membranes The main toxic action will be depression of the central nervous svstem with symptoms of giddiness, dizziness, hilarity, and headache not unlike an alcoholic intoxication Mild symptoms of this sort are apt to be produced by relatively short exposures to concentrations of 500 to 750 ppm of this kind of gasoline In addi tion, mild blood changes, neuritis, and neu rasthenias have been reported If the gasoline is made from a crude oil containing 40 per cent or more of aromatics or is enriched in aromatics by the refining process, the toxicity mav be substantially higher The tetraethyl lead content of gasoline is low enough to make any lead exposures from ordinary handling and dispensing of gasoline in garages and filling stations negligible Tetraethyl lead can however present a toxic hazard by inhalation and absorption through the skin when entry is made into tanks and other confined spaces that have contained leaded gasoline See Lead and Hygienic Guide Germanium, one of the less common metals which have some industrial uses, is employed particularly in the electronics industry for diodes and transistors It appears to be a relatively inert metal and has not been re ported as the cause of any occupational dis eases in man In animal experiments, the LD50 for rats bv intraperitonea! injection was about 750 mg/kg of body weight when germanium oxide was buffered to near the neutral point Food containing 1000 ppm or water containing 100 ppm was fatal to half of the young rats Repeated sublethal doses produced some tolerance to a subsequent lethal dose, but the tolerance declined substantially m six weeks Graphite has been repeatedly reported to produce a pneumoconiosis in workers m mines, mills, and electrode plants Several investigators have done autopsies on men who died from graphite pneumoconiosis and found their lungs to contain fibrous masses with central necrosis, in addition to emphy sema and general fibrosis around the blood vessels and lymph channels The typical X-ray patterns start with a military "snow storm" effect and progress to a pattern of sharply defined masses of various sizes m each lobe Halogenated hydrocarbons -- see also the individual compounds--as used m industry are potent anesthetics and more or less toxic On exposure to high concentrations the most common symptoms are nausea, vomiting, diarrhea, headache, and unconsciousness If unconsciousness occurs, it mav be fol lowed by sudden death due to fibrillation of the heart or respiratory failure, as has fre quently been observed m the medical use of these compounds After exposure to amounts which are large but not sufficient to produce sudden death, there may be severe kidney and liver damage eventually leading to death The most common halogenated hydrocar bons, arranged in the order of increasingly acute toxicity, are vinyl chloride, methyl chloride, ethyl chloride, ethylene dichloride, ethyl bromide, carbon tetrachloride, dichloromethane, methyl chloroform, trichloroethy lene, methyl bromide, tetrachloroethylene, pentachloroethane, and tetrachloroethane Tetrachloroethane is about 40 times as strong a narcotic as vinyl chloride It should be noted that this is the increas ing order of their ability to produce nar cosis, which is not the same as the order of their chronic toxicity, the more common prob lem in industry An acute exposure to the more narcotic of these compounds may re sult in unconsciousness for suprisinglv long periods, with eventual recovery Uncon sciousness for eight weeks has been reported in a case of methyl bromide poisoning Tetrachloroethane, the most toxic of the common chlorinated hydrocarbons, has no particular warning signs or symptoms and can produce extremely severe poisonings from continuous exposure to fairly low con centrations Carbon tetrachloride, methyl 1350