The patient after exposure for some time suffers from violent headache, giddiness, and sickness; he has sensations of cold, pains in the limbs, a feeling of ‘needles and pins,’ and itching in different parts of the body. Gradually a condition of general excitement develops. Sleeplessness, cramps, and palpitation set in. At the same time the nervous system becomes involved—hypersensitiveness, loss of sensation or complete numbness of some parts of the skin, diminution of muscular power, disturbances of movement, twitching, violent trembling, wasting of the muscles, and paralysis; the sight also is sometimes affected. The stage of excitement, in which the patient often becomes strikingly loquacious without cause, passes gradually, as the nervous symptoms develop, into the stage of depression; sometimes this takes weeks and months; excitement and gaiety give place to deep depression; other symptoms appear—weakness of memory, mental dulness, and difficulty in speaking. The powers of sensation become affected, paralysis increases, and digestive disturbances, anæmia, and general loss of strength are manifest. Occasionally definite mental disease (psychosis, mania, melancholia, dementia, &c.) develops.
Certain cases of chronic carbon bisulphide poisoning in indiarubber workers have come under my notice, and some remarks concerning them may be of interest. The characteristic symptoms are essentially as follows: the invalid appears in the consulting-room in a bent position, leaning upon a stick with head and hands shaking. The gait is clumsy (spastic-paralysis) so that the patient ‘steps’ rather than walks. When seated, the tremor ceases to some extent, but in purposive movements increases rapidly, involving the whole body, so that an exact systematic examination becomes impossible, and the invalid sinks back into the chair exhausted and bathed in perspiration. He complains of cold in the extremities. He looks pale; the skin of the upper extremities is totally without feeling, as also is the upper part of the feet; the skin of the head is hypersensitive; the muscular strength of the arms is almost lost; testing the strength brings on marked shaking, followed by a fainting-fit caused by exhaustion. The extremities of the patient are cyanotic (livid); the knee jerks are exaggerated. The patient suffers from indigestion, constipation, headache, and giddiness; he is irritable, and depressed; his memory is weak; mental derangement cannot be proved.
Chronic carbon bisulphide poisoning is rarely fatal. Slight cases end in recovery after more or less long continuance; in severe cases improvement occasionally takes place, but serious nervous disturbance (paralysis, weakness of the muscles, deterioration of intellect) usually persists.
Treatment is symptomatic, aiming especially at relieving the nervous symptoms and improving the state of nutrition. If psychical disturbances are prominent, treatment in an institution is necessary.
CYANOGEN AND CYANOGEN COMPOUNDS (CYANOGEN GAS, PRUSSIC ACID, CYANIDES)
Industrial cyanogen poisoning is not frequent. Cyanogen gas (C₂N₂, existing in small quantities in furnace gas, illuminating gas, and other kinds of gas) and especially hydrocyanic acid (CNH, prussic acid) are considered industrial poisons; the latter is a very unstable, colourless, pungent-smelling liquid, boiling at 27° C. Among the cyanides employed industrially and having an effect similar to that of prussic acid must be mentioned cyanide of potassium and cyanide of sodium (KCN and NaCN), cyanide of silver (AgCN) and cyanide of mercury (Hg[CN]₂).
Cyanogen and cyanogen compounds are extraordinarily powerful poisons. The minimum dose lies, as Lehmann has proved by experiments on animals, at about 0·05 per thousand of hydrocyanic acid in the atmosphere breathed; 1-5 mg. per kg. weight is fatal to animals; to man about 60 mg. would be fatal.
The poisonous action of cyanogen and cyanogen compounds depends upon their power of preventing absorption of oxygen from the blood by the tissues with the result that the venous blood flowing to the heart retains the bright red colour which otherwise only arterial blood exhibits. This effect is due to cessation of the gaseous exchange in the body, and results in tissue suffocation. At the same time these poisons have at first an exciting and then a paralysing effect upon the central nervous system. In severe poisoning the nerve effect is masked by the effect upon the exchange of gases in the blood, since this quickly leads to death.
Most of the cases of industrial poisoning under this heading result from inhalation; absorption of liquid cyanogen compounds through the skin can rarely come into consideration.