Modern synthetic insecticides, including DDT (dichloro-diphenyl-trichloroethane) came into use in the 1940s. DDT was initially used with great effect to combat malaria, typhus, and the other insect-borne human diseases among both military and civilian populations and for insect control in crop and livestock production, institutions, homes, and gardens. Concerns about the harmful effects of these pesticides were voiced in the entomological and other scientific literature well before Rachel Carson's 1962 book Silent Spring sounded an alarm. Among the concerns were for their broad toxicity which killed beneficial insects and that not enough was known about their effects on plants, animals and soils. Some scientist urged caution and more limited use until research was complete on health and environmental effects. For a good review of this debate, read Professional Entomology and the 44 Noisy Years since Silent Spring at http://extension.entm.purdue.edu/fieldcropsipm/pubs/7.pdf . The U.S. Department of Agriculture, the federal agency with responsibility of regulating pesticides before the formation of the U.S. Environmental Protection Agency in 1970, began regulatory actions in the late 1950s and 1960s to prohibit many of DDT's uses because of mounting evidence of the pesticide's declining benefits and environmental and toxicological effects. Rachel Carson's book Silent Spring in 1962 stimulated widespread public concern over the dangers of improper pesticide use and the need for better pesticide controls. 1972, EPA issued a cancellation order for DDT based on adverse environmental effects of its use, such as those to wildlife, as well as DDT's potential human health risks. This 1958 film, Health Hazards of Pesticides, was produced by the Public Health Service of the U.S. Communicable Disease Center (CDC). The film emphasizes the potential public health hazards resulting from the widespread use of pesticides and explains the work of the Communicable Disease Center's toxicology laboratories in Wenatchee, Washington, Savannah, Georgia and Chattanooga, Tennessee . The technical advisor, Wayland Hayes was a toxicologist with the CDC who strongly supported the use of pesticides and generally believed the major problem was with misuse and accidental poisonings. Of pesticides, the wrote in 1954: Among the hazards are the excessive exposure of workers who manufacture, formulate, or apply the materials; the accidental exposure of children or other irresponsible persons; and the exposure of the general population in the event that residues on food should ever be allowed to approach the toxic level. However, few accidents occur if instructions for the use of the chemicals are followed and the prescribed precautions are taken. The public health benefits from the use of agricultural chemicals should always be kept in mind in considering the potential hazards involved in the use of these materials. Hayes conducted toxicity studies on human volunteer subjects, including a study on DDT using prisoners in 1956. The experiments were carried out on several dozen prisoners from the Atlanta Penitentiary who agreed to take part. Human subjects received daily doses of 35 mg DDT for almost two years and some were observed for several years after the last dose. Hayes stated that no harmful effects were found by medical examination. Fifty one prisoners began the study with many dropping out after a few days. Critics pointed out the human health questions left unanswered by his study: DDT's long-term toxicity; its effects on the endocrine system and liver; and its effects on newborns, children, and women.
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Pesticides in Agriculture.avi.AVIby archipelagogr1,514 views
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