(Journal of the American Medical Association.) The Massachusetts Industrial Accident Board (1915) estimates 75,000 fatal accidents yearly to workers of all ages and more than 3,000,000 non-fatal accidents.

Drowning may be classed as mechanical injury to human life. There were in 1915, in the area of registration, 6,514 deaths from accidental drowning. This is a very strong argument in favor of a swimming requirement for all children.

Murder and suicide are commonly effected by mechanical means though not infrequently chemical. Reports from the registration area containing 67.1 per cent. of the total population of the United States indicate that in 1915 there were in this area 11,216 suicides and 4,670 homicides.

During its first five months, the Great War was responsible for the loss of more than two million human lives. The gross direct injuries of war are largely mechanical. Estimates made in 1919 place the number above 9,000,000. (War has a powerful contributory influence on communicable disease, an emphasis on hereditary degeneracies, and a destructive effect on community morals, not to be confused with the direct mechanical effect of powder and ball.)

Mechanical injury figures largely in the affairs of every community through all divisions of the population. The laborer is most often affected, but accidents involving mechanical injury of varying degree of seriousness are common to all classes.

Mechanical injuries are in a very large degree preventable. Safety appliances are being adopted commonly in our industrial plants. "Better safe than sorry," is the motto of many a "Safety First" campaign in our larger communities. It is a good motto for individual guidance. If half these injurious and fatal accidents could be avoided each year, the saving in human life, human suffering and human misery would be

enormous.

What have you done to protect yourself from mechanical injury? Have you the muscle and the nerve to control a runaway horse? Could you save your life by climbing down a rope fire-escape? Can you jump quickly enough and far enough to avoid an automobile? Can you run fast enough to get out of the way? Could you run long enough? Could you escape from a sinking boat? A hundred feet from shore? A half mile? Can you swim? What are you prepared to do to defend yourself and your country from the mechanical injuries of war?

THE PHYSICAL AGENTS THAT INJURE HEALTH

The physical agents that injure health may be classified as follows: (a) Atmospheric pressure, diminished pressure, excessive pressure; (b) temperature, low temperature, high temperature; (c) light, insufficient light, excessive light; (d) the X-ray; (e) radium; (f) electricity, lightning, commercial electricity.

Variations in atmospheric pressure are not of much importance in the affairs of the ordinary individual. Those who climb high mountains or make balloon ascensions to great heights may suffer with giddiness, rapid breathing, rapid heart rate, nose-bleed, weakness and exhaustion. These are effects of low atmospheric pressure. They are symptoms due to an insufficient supply of oxygen in the blood. Men that work in caissons, building tunnels under rivers, for instance, suffer from the effects of high air pressure. The laborer who returns from such work to normal air pressure too rapidly suffers excruciating pain, and, in some cases, death. The excessive air pressure forces the blood to take on an increased amount of oxygen, nitrogen and carbon dioxide gas. When the excessive pressure is reduced suddenly, it seems that the blood is unable to get rid of its increased amount of nitrogen as rapidly as it does the other gases it has taken up. The bubbles of nitrogen remaining in the blood cause the pain and fatality.

Variations in temperature are of importance in temperate and arctic

zones.

Low temperature causes chilblains, frost bites and freezing, none of which are common or of much importance in this part of the world. In colder climates they are of more serious concern. Six persons froze to death in New York City in the winter of 1916. Three hundred and fifty-four persons died of excessive cold in the area of registration in 1918.

Cold may lower the temperature of the body and thus reduce its resistance to disease.

High temperature may cause: (1) Heat stroke-a result of hot, moist weather-may be headache, rapid pulse, rapid respiration, loss of consciousness, death. In 1915, area of registration, there was 407 deaths from effects of heat. (2) Burns; may vary in degree from simple redness to cremation. Death follows if half the body is burned enough to cause blisters. Death follows if from one-sixth to oneeighth of the skin surface is destroyed by burning. Burned areas are easily infected. The septic wounds that occur in such areas are often

very serious. The scars that follow burns may cause incapacitating deformities. In the area of registration (1915) there were 4,804 persons accidentally burned to death; in addition, 971 lost their lives in con▾ flagrations. In New York City in 1916, 428 persons were fatally burned.

Light as a source of injury to health. Insufficient light; not a specific cause of disease; may contribute to produce, or help produce poor health. A factor in causing eye strain.

Excess of light, particularly sunlight. The red rays of the sun produce heat. They are factors in heat stroke referred to above. The violet rays and the ultra-violet rays of the sun are of special importance. They may cause sunstroke when the rays of the sun fall directly on the head and neck. The symptoms of sunstroke are pains in the head and neck, nervous excitement, convulsions and loss of consciousness. Death may come in an hour. In the summer of 1916, fiftyeight persons in New York City died of sunstroke. Milder cases recover, but they frequently develop a permanent nervous disorder of some sort. These rays (violet and ultra-violet) cause sunburn. Severe sunburn is very painful. The burned area may easily become infected. The X-ray and radium rays are sometimes causes of disease among the specialists who use them or work with them. These rays may cause sterility in the men and women. They sometimes cause “burns” that develop into cancerous growths.

Electricity as a physical cause of injury. Lightning may cause death or prolonged unconsciousness. Burns from lightning heal very slowly. Commercial electricity used for service and for industrial purposes is frequently the cause of injury. The seriousness of this injury depends on the amount of current that passes through the victim; the area of contact, and the region affected. Currents of low voltage and moderate frequency may be fatal if the heart is in the circuit. The electric current may cause nervous disturbances, burns, loss of vision and death. Five hundred and fifteen deaths were reported from electricity (lightning excluded) in 1915 in the area of registration. Two hundred and twenty-one were reported due to lightning. It not infrequently happens that the heart continues to beat after breathing has been stopped by the electric current. In such cases the use of artificial respiration may save the victim from dying. (The best method of artificial respiration is the Schafer or the prone pressure method.) One should never handle loose electric wires, switches, unless he is certain of their safety and of his own protection. Carelessness has often lead to fatality.

VII

THE CHEMICAL AGENTS THAT INJURE HEALTH

Acute poisoning not included in this discussion. It may be noted, however, that there were 1,286 deaths reported in the area of registration from acute poisoning in 1915. Chemical agents may exist in solid, liquor, or gaseous forms. They may be either inorganic chemicals or organic chemicals.

The Inorganic Chemicals that Injure Health

Lead. The cause of chronic lead poisoning.

Source.-Poisoning from lead is common in those industries in which lead is handled, e.g., lead mining and smelting, zinc smelting, working in lead and lead colors, making lead pipes and various other lead objects, making pottery and earthenware, type making, working in electric storage battery factories, and installing gas and water pipes. Susceptibility.-Increased by bad habits, lack of condition, chronic

illness.

Mode of Entrance.-Skin absorption plays a part. Inhalation of vapor of lead is a "questionable occurrence." Ingestion into the stomach is the important route.

Symptoms. Varied and inconstant. May be colic, paralysis, convulsions, delirium and death. One hundred and fifty-five deaths from chronic poisoning are reported for the area of registration in 1915. Most cases recover. (For effects on offspring see chapter on "Inheritance" and the "Prenatal Period.")

Avoidance. Poisoning by lead is avoidable through habits of cleanliness. Lead workers should wear gloves when practicable; always wash their hands before eating; never put their fingers in their mouths; omit smoking while hands are smeared with lead compositions; exercise care that their food is not contaminated with lead.

Arsenic. The cause of chronic arsenical poisoning. Importance has greatly decreased in recent years. Source of poisoning from arsenic is now limited to arsenical beer (England); a few industrial occupations; criminal usage; and the therapeutic use of the drug (Edsall). Massachusetts law in 1900 limited the amount of arsenic to be used in coloring paper and articles of dress. Country is now almost free of poisoning from this source.

Mode of Entrance.—Inhalation; external application; ingestion.

Mercury. The cause of chronic mercurial poisoning. Importance has greatly decreased since greater care is being used in administering

mercury medically, and since mercury is now less commonly used industrially. Chief sources of mercury poisoning now are mercury mining and smelting, manufacturing of thermometers and barometers, and the manufacture of felt hats.

Mode of Entrance.-Inhalation of vapor, the chief avenue of entry. Absorption through the skin also important. Ingestion not common.

Symptoms.-Chiefly mental, nervous mental, nervous and digestive. Recovery probable in mild cases. (For effect on offspring see chapters on "Inheritance" and the "Prenatal Period.")

Phosphorus.-The cause of chronic phosphorus poisoning. The importance of phosphorus poisoning has greatly decreased in recent years because of stringent laws and improved methods of manufacture. Chief source is the white phosphorus used in making matches.

Mode of Entrance.-Ingestion. Symptoms may be severe. Necrosis of the bones of the jaws is the most common local symptom. This necrosis reaches the surrounding tissues and may become extensive. Foul odor, repulsive appearance, deformity, and death are not uncommon effects of the disease.

Prevention.-Stop using white phosphorus. Keep the mouths of working people clean.

Carbon Monoxide.-Importance is increasing because of the opportunities for acute and chronic poisoning from various industrial sources. Sources.-Pure carbon monoxide (from electric furnaces) illuminating gas; products of combustion.

Mode of Entrance.--Inhalation. Symptoms arise from injuries to the blood, kidneys and brain. Three hundred and forty-five persons lost their lives from illuminating gas in New York City in 1916.

The Great War has produced some new poisonous chemicals of terrible power. The gases used in offensive warfare include chlorine, phosgene, xylil bromid or benzyl bromid, phenzl carbylamin chlorid, diphenyl-chloroarsin, dichloro-diethzlsulphid. Used as gas clouds, in gas bombs, and in gas shells. Protective devices have been produced for all these gases.

The manufacture of high explosives is accompanied by danger to the workmen because of the poisonous properties of some of the chemicals used. Among the most dangerous in this class are picric · acid, trinitrotoluol, and the fulminate of mercury.