6. Mercury.—A variety of different mercury salts and the metal itself may produce intoxication from the action of either dust or fumes. Thus we find that cinnibar roasters, workers in the extraction of gold and silver, the users of mercury air pumps, barometer or thermometer manufactures, water gilders and felt hat and fur dressers may become intoxicated. Its prevention chiefly requires improvement in ventilating facilities.
7. Benzin and Benzol.—These are chiefly used as solvents for quick drying paints and varnishes, for cements and blacking.
Those exposed are chiefly cementers in the rubber and boot and shoe industries, as well as dry cleaners and painters. They produce faintness and stupor. Adequate ventilation is re quired for prevention. (Fig. 109).
8. Zinc Poisoning (Brass Founders Ague).—Brass is an alloy of zinc and copper in varying proportions. When brass is melted a considerable volume of zinc oxide is given off as fumes. (See Fig. to). Thus brass moulders are chiefly exposed, though brass polishers suffer to a lesser extent. The attacks are acute and come on several hours after exposure. The workmen suffer from rigors followed by a fever, the whole lasting several hours. Chronically it may also produce asthmatic and bronchial symptoms. Efficient exhaust ventila tion is required as a remedy.
9. Pneumonokoniosis.—Pneumonokoniosis is a chronic inter stitial pneumonia accompanied by a deposit of pigment and usually due to dust encountered under conditions of employ ment. The physical character of the dust is an important factor in the development of the condition. It affects workers in coal and stone, clay, iron, wool, flour, tobacco, iron oxide, ultramarine blue, hair, cotton, shell, leather and wool.
Dust enters the lungs both by inhalation and the alimentary tract. Inhalation is probably the most important route. The inhaled particles pass to the alveoli despite the obstacles presented by the ciliated epithelium and the minute subdivi sions of the bronchioles. They are ingested by the phagocytic epithelial cells which carry them to the connective tissue frame work of the lungs or to the lymphatics, and are later deposited in the bronchial glands. Those which settle in the mouth are
enmeshed in the pharyngeal mucus and swallowed. Phagocytes carry them through the intestinal walls to the lymphatics, by which route they are carried to the lungs.
An important related point is the fact that about seventy per cent. of these persons develop pulmonary tuberculosis, doubtless due to the irritation developed. Tuberculosis mortality is about four times as great among workers in dusty trades as in the population as a whole. The harder and sharper the dust the more likely is the condition to develop. It is relatively rare among workers in organic dust, in whom the dust usually sets up a chronic catarrhal condition which only rarely leads to structural changes. Various terms are used to designate this condition when produced by different dusts. Thus in: (a) Coal miners (especially in hard coal) it is known as Anthracosis.
(b) Quartz miners (gold) it is known as Silicosis.
(c) Stone grinders it is known as Silicosis or Chalcicosis.
(d) Pottery workers it is known as Aluminosis.
(e) Iron or steel grinders it is known as Siderosis. .i)Tobacco workers it is known as Tobaccosis and g) Cotton workers it is known as Byssinosis.
The degree to which it developer among workers exposed to hard dust is very high. Ganister disease is a form of silicosis.
The men are engaged in making the brick lining for smelters and retorts. Thus per one thousand men in the ganister trade, 42.3 miners, 179.8 grinders and 22.2 brickmakers die of silicosis. In the zinc mines of Joplin Alo. 66 per cent. of all miners have evidence of pulmonary disease.
The available remedies are based upon dust removal and reduction. Thus exhaust ventilation should be employed where possible and the workmen required to use respirators.
Wetting down of the abrasive work and wet processes should be used where ever possible. (Fig. III).