In the general poisoning produced by inhalation of petroleum fumes the effect upon the central nervous system is all the more plainly and clearly marked when the irritant effect of the hydrocarbons boiling at higher temperature is slight or absent; that is, in the case of poisoning which arises solely from industrial products of low boiling hydrocarbons; among these benzine is included.
Acute poisoning from inhalation of benzine fumes begins with headache, sickness, and attacks of giddiness resembling alcoholic intoxication. If very much has been inhaled, the patient quickly becomes unconscious, with occasionally muscular tremors, convulsions, difficulty in breathing, and cyanosis.
In cases of poisoning by inhalation of fumes of crude petroleum, these symptoms may be complicated by coughing, intense inflammation of the mucous membrane of the respiratory organs—congestion, bronchitis, bloodstained expectoration, and inflammation of the lungs. In workers who frequently remain long in an atmosphere filled with benzine fumes, further symptoms of chronic benzine poisoning show themselves—mental hebetude, pains in the limbs, trembling, weakness of the muscles, and other disturbances of the nervous system; in such cases these may really be signs of continued attacks of acute or sub-acute poisoning; many benzine workers are anæmic.
The treatment of acute benzine poisoning consists in oxygen inhalation, with simultaneous artificial respiration. Treatment of chronic derangement of health is symptomatic.
HYDROCARBONS OF THE AROMATIC SERIES
BENZENE AND ITS HOMOLOGUES
Benzene (C₆H₆) is a characteristically smelling (aromatic) liquid which boils at 80·5° C. Acute benzene poisoning, which plays an important part as an industrial poisoning, is caused by inhalation of benzene fumes. The various kinds of benzol used commercially contain, besides benzene, alkyl benzenes, especially toluene (methylbenzene, C₆H₅.CH₃, boiling-point 111° C.); xylene (dimethylbenzene, C₆H₄[CH₃]₂, boiling-point 140° C.); pseudocumene and mesitylene (tri-methylbenzene, C₆H₃[CH₃]₃, boiling-point 169° or 163° C.); the regular presence of thiophene (C₄H₄S, boiling-point 84° C.) in commercial benzol must also be taken into account. Industrial benzol poisoning arises, therefore, as a rule, not from the action of pure benzene vapour, but from fumes which contain a mixture of the compounds mentioned.
The course run by industrial benzol poisoning is often very acute, if large quantities are inhaled—death occurring suddenly, after a short illness with symptoms of vertigo. Gradual inhalation of lesser quantities gives rise to headache, giddiness, malaise, then twitchings appear which develop into convulsions, and lastly unconsciousness. In order to ascertain in what manner the various substances contained in commercial benzol share in the poisonous effect, experimental research seemed to me to be indispensable, especially as published statements so far gave no accurate data.
Two cases of industrial benzol poisoning have given rise to close experimental research upon the poisonous nature of benzene.
Lewin undertook experiments on animals; which he confined under bells and caused to inhale fumes of chemically pure and impure benzene. He mentions that even at comparatively low concentration poisoning results, and indeed more readily and certainly from the action of impure than pure benzene. Lewin found that when air was made to flow slowly first through benzene and then into the bell, symptoms of paralysis, convulsions, and unconsciousness showed themselves in from four to six minutes. After-effects by this means could not be observed. Lewin maintains, however, that in man even slight acute action of benzene can be followed by after-effects (giddiness, sickness, headache, distress in breathing, and oppression of the heart).