The influence of sand blasting is very in jurious to the mucous membrane of the mouth, throat and nose, and upon the bronchi and lungs, unless the face is protected by a suitable mask. Workers in bronze, chromic acid, cobalt, copper, manganese, platinum, silver and zinc may be poisoned by dust or fumes, but those who work in gold, iron, steel, nickel and tin are not injured except by the dust, or by solder which may be used in working them. The effect of toxic gases is local or general, acute or chronic, and they are eliminated by the lungs or kidneys.
The list of poisonous gases which produce disease or death is a long one, among them being bromine, carbon bisulphide, dioxide and monoxide, chlorine, the vapor from essences, extracts and essential oils, ether, formaldehyde, gasoline, naphtha, iodine, wood alcohol and turpentine, and the gas from phosphorus and sulphur. The inhalation of ammonia and ammonium chloride produces cough, sneezing, catarrh and bronchitis. The clothing of those who work in amyl alcohol and amilin may be come so saturated that unconsciousness and death may follow prolonged inhalation of the gases as they are volatilized. Benzine vapor is very poisonous and may produce an acute or chronic disease.
Workers in dyes, petroleum, alkalis and carbolic, nitric, hydrochloric and sulphuric acids suffer mostly from the direct effect upon the mucous membrane of the respiratory organs. Those who work in nitro-glycerine soon acquire immunity, as it is readily absorbed. The injury from organic dust and fibre which occurs for example, to those who work in grist mills, Frain elevators, sugar refineries, etc., consists in mechanical obstruction in the respiratory passages, in the bruising of the mucous mem brane, in the inhalation of soluble poisons and germs and in the irritation of the skin, eyes, ears and mouth. Other substances which may cause irritation by being received into the body in the course of one's occupation and which may be mentioned in this relation are all those which are connected with the work of miners, asphalt, cement, emery, glass and stones, metals and . earths which are ground or crushed or polished. The cleaning occupations are very productive of disease through inhalation, in cluding the gathering of ashes and garbage, street cleaning, carpet cleaning, and the me chanical treatments of cotton, felt, feathers, flax, hemp, fur, horn, bone, shell, horsehair, jute, rags, straw, tobacco, wool and rubber.
The harmful occupations which are due to bad physical surroundings are those of workers in caissons and tunnels, in which the so-called caisson or compressed air disease is produced, and also conditions in which there is air con cussion or air rarefaction. In this category must also be included those occupations in which the conditions of heat, cold, moisture or light are excessive or abnormal.
If we turn our attention to specific trades and occupations we see that farmers, though working 3n the open air and, under ordinary circumstances, having the best chance for im munity from disease, are nevertheless very often victims of disease of the digestive -ap paratus and sufferers from bad teeth owing to the large quantities of indigestible, poorly cooked and imperfectly masticated food which are eaten by so many of them and the failure to give proper attention to their teeth.
Fishermen and sailors are also sufferers from similar diseases and from pneumonia and tuberculosis owing to exposure to bad sanita tion at home and on shipboard, bad habits, and too exclusive a diet of fish, salt pork and other cured foods.
Those who contract anaemia, tuberculosis and many diseases of the lungs, teeth, mucous membrane and skin in connection with their occupation, owing to bad air or to irritating dust or gas which they inhale, include tanners, blacksmiths, miners, bakers, millers, knife grinders, and many others.
The diseases from working in metals, with serious or fatal poisonous effects and injuries to both soft and hard tissues, affect workers in copper, lead, arsenic, phosphorus, mercury, zinc, tin and brass.
Railroad men, especially those who work on trains, have the usual ailments which come from exposure, such as rheumatism, eye strain and other eye troubles, and kidney disease from excessive shaking, while they are continually in danger from serious accidents.
The workers in tunnels and caissons and in other places where the air pressure may be as great as four or five atmospheres suffer seri ously with their blood and nervous system, air being forced into the nervous tissue which is not always dislodged, even by careful de compression, when the victim returns to or dinary atmospheric conditions.