Organic arsenicals history

The early history of Ehrlich s work with organic arsenicals was mentioned (Chapter 2). Arsenicals were important in the treatment of tropical protozoal diseases as well as syphilis until the advent of the sulfonamides in 1935. Today they are utilized mainly in trypanosomiasis. They are among the least well-tolerated drugs in use today and usually require hospitalization to manage toxic effects. 

Poisons usually enter a body through the mouth or nose, but some substances may be absorbed through the skin. Susceptibility to poisons depends on an organism s individual characteristics, such as age, mass, past history, general health, and body chemistry. Some toxins, such as lead, mercury, and arsenic, can accumulate in the body and may cause problems over a long period of time. 

Overall Metabolic Processes. In general, metabolic processes which facilitate elimination of a pesticide from the body are considered desirable. This is based a great deal on our long history of associating toxicity with chemicals that accumulate in the body. Arsenic, lead, mercury and other metals substantiate these concerns as do more modern synthetic organic chemicals such as DDT and mirex. Because so many chemicals rapidly voided from the body are now known to be extremely hazardous, risks and excretion rates are evaluated very carefully. Still, storage of metabolites is not a positive characteristic even for those compounds like DDE whose danger, if any, as a body burden has not been established. 

Throughout history, various types of pests, such as insects, weeds, bacteria, rodents, and other biological organisms, have bothered humans or threatened human health. People have been nsing pesticides for thousands of years to try to control these pests. The Snmerians used sulfur to control insects and mites 5,000 years ago. The Chinese used mercury and arsenic compotmds to control body lice and other pests. The Greeks and Romans used oil, ash, sulfur, and other materials to protect themselves, their hvestock, and their crops from various pests. And people in various cultures have used smoke, salt, spices, and insect-repelling plants to preserve food and keep pests away. 

However, there are also chemicals we can do without. A living organism always tries to enhance its own survival it is the basic nature of living things. In that effort, an organism may create a substance that is harmful to others this is a natural defense mechanism. Such a substance is a natural chemical weapon and can be harmful to the human body (i.e., natural toxin), and we can do without it. People have used throughout history a variety of chemicals with an intention to harm others poisons (of arsenic, cyanide, many poisons (alkaloids and others) obtained from plants and others), explosives and chemical weapons (mostly neurotoxins). We are better off without them. I must hasten to add, though, that some of these chemicals can be used for useful purposes as well. 

In connection with lipoic acid chemistry, mention should be made of arsenic compounds, some of the oldest and best-known poisons used throughout history. More recently, organic derivatives have been used as fungicides and insecticides. The more important arsenic compounds from a toxic stand point are trivalent compounds. Arsenite (0=As — O ) for instance is noted for its tendency to react rapidly with thiol groups, especially dithiols such as reduced lipoic acid. The result is that by blocking oxidative enzymes which require lipoic acid, arsenite causes the accumulation of pyruvate and other a-keto acids. 

For details on material controls in World War II see (1) Donald M. Nelson, Arsenal of Democracy (New York Harcoutt Brace, 1946) (2) Civilian Production Administration, Industrial Mobilization for 9 ar History of the War Production Board and Predecessor Agencies, 1940-1943 (Washington, 1947), vol. I, pp. 457-74 (3) Smith, The Army and Economic Mobilization, pt. VI, chs. XXII-XXVI and (4) Millett, Organization and Pole of the Army Service Forces, ch, XIV. 

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