Nitrotoluene (C₆H₄CH₃NO₂), of which the ortho-compound acts most powerfully, and also nitroxylene (C₆H₃[CH₃]₂NO₂) have similar but less marked effect.
The dinitrobenzenes (C₆H₄[NO₂]₂) are stable bodies. Meta-dinitrobenzene inhaled as dust or otherwise, can produce marked poisoning symptoms essentially the same as those described. Especially characteristic is the early dark discoloration of the skin.
Symptoms resembling nitrobenzene poisoning in general are caused by nitrophenols (C₆H₄.OH.NO₂), of which paranitrophenol is the most toxic; also by dinitrophenols (C₆H₃[NO₂]₂OH), solid crystalline substances which melt at different temperatures, and the mono- and di-nitrochlorobenzenes (C₆H₄.Cl.NO₂ and C₆H₃.Cl[NO₂]₂). In cases of industrial poisoning by dinitrophenol, observed by Leymann, the workers were taken suddenly ill, with symptoms of collapse, pains in the chest, vomiting, distress of breathing, rapid pulse, and convulsions, and died within a few hours. At the autopsy a yellow substance was found with picric acid reaction which appeared to be di- or tri-nitrophenol. In other cases, some fatal, of industrial nitrochlorobenzene poisoning, also observed by Leymann, the typical grey-blue discoloration of the skin was obvious, and the chocolate-brown colour of the blood produced by methæmoglobin.
Trinitrophenol (picric acid, C₆H₂[NO₂]₃OH) is a yellow crystalline compound with bitter taste; poisoning by this substance exhibits clearly strong local irritant action (upon skin, mucous membrane, and intestinal canal, and especially upon the kidneys), besides effect on the blood and central nervous system. Prolonged action of picric acid upon the skin causes inflammation. Absorption of picric acid dust causes inflammation of the mucous membrane of the respiratory passages and symptoms of gastric and intestinal catarrh as well as inflammation of the kidneys.
A jaundice-like discoloration of the skin and darkening of the urine are also characteristic; sometimes picric acid poisoning produces a rash resembling that of measles and scarlet fever.
Nitronaphthalene (C₁₀H₇[NO₂]) and nitronaphthol (C₁₀H₆.NO₂.OH) in addition to methæmoglobin formation have an irritant action. It is stated also that dulness of the cornea is produced.
Azobenzenes also, which are to be considered as intermediate between nitrobenzene and aniline, form methæmoglobin (azobenzene, C₆H₅N = NH₅C₆).
Aniline (amidobenzene, C₆H₅.NH₂), a colourless, oily liquid of aromatic smell, has only slight local irritant effect. In the frequent cases of industrial poisoning by ‘aniline oil’ or aniline hydrochloride, in which the aniline enters through the skin or is inhaled in the form of fume, there appear the typical symptoms common to this group, of the action upon the blood through methæmoglobin formation: headache, weakness, cyanosis, difficulty in breathing, &c., to which are added nervous symptoms such as convulsions and psychical disturbance, although these play a subordinate part in industrial poisoning. In severe cases the typical symptoms of air hunger are shown. Occasionally recovery only takes place gradually, and signs of irritation of the kidneys and inflammation of the urinary organs are seen. These symptoms occur only rarely in acute industrial poisoning, but are, however, in so far worthy of notice because of the frequent occurrence of tumours in the bladder among aniline workers. It is possible that here the irritant action of the urine which contains aniline plays a part. The tumours in the bladder operated upon, in some cases with success, were many of them non-malignant (papillomata), but some were carcinomata (cancerous new growths) running a malignant course, and recurring after operation. In the urine the aniline combines with sulphuric acid, and is partly excreted as paramidophenol sulphuric acid.
The treatment of aniline poisoning is the same as that for all the poisons of this group. In view of the occurrence of tumours of the bladder in aniline workers, they should be instructed to seek medical aid on the first indications of trouble, so that a careful cystoscopic examination may be made.
Toluidine (C₆H₄.CH₃.NH₂), which is mixed with aniline for industrial use, produces the same symptoms with marked irritation of the renal organs.