Public Health Aspects of Agricultural Chemicals HERBERT K. ABRAMS
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Department of Public Health, State of California, Berkeley 2, Calif.
A well planned public health program is needed for the safe exploitation of agricultural chemicals. This should embody research on toxicity, cooperation of public and private agencies for exchange of information and promulgation of control measures, labeling of economic poisons, adequate inspection, and education in occupational and consumer health.
In 1900, rural people were generally healthier than people who lived i n the city (7). F i f t y years ago the length of life among white males i n the rural areas was ten years, and among white females, seven and a half years, longer than that of the same groups who lived i n the city. Since this time, health conditions have improved markedly i n urban centers but more slowly i n rural areas, so that today the life expectancy of rural and urban populations i n the United States is approximately the same. Undoubtedly a major reason for this development is the improvement of medical care and public health services i n the cities, while the rural areas have lagged i n this respect. Coincidentally, agriculture and allied activities have become highly industrialized. Today the farm is a 'factory i n the field." It is perhaps not generally known that accidental deaths are much higher i n the rural areas than i n the cities. F o r example, i n 1948 there were 55 accidental deaths per 100,000 agricultural workers as contrasted with 16 per 100,000 manufacturing workers. I n addition to accidents, the farmer is the special target of many other occupationally associated conditions, such as the diseases transmitted b y contact with plants and animals; conditions resulting from excessive exposure to sunlight, such as actinic dermatitis and skin cancer; and skeletal difficulties, such as arthritis, myositis, and others resulting from strenuous physical labor plus exposure to the elements. Finally, w i t h the enormous strides made i n recent years i n the sciences, farming has now become a mass production industry, using practically every type of chemical. Today no significant agricultural production is achieved without the aid of chemical adjuncts. 1
Importance of Agricultural Chemicals Reports of occupational diseases sent to the California Department of Public Health reveal strikingly that it is "one w o r l d " so far as hazards to health among occupational groups are concerned. The same chemical may cause illness to the factory worker who manufactures it, to the truckers and stevedores who handle and transport it, to the farmer who uses the material, to the packers and canners of the food treated with i t , and to the person who consumes the foods that may be contaminated with i t . There are 80,000 kinds of insects i n N o r t h America, at least 5000 of which are known to be of economic importance. The estimated damage to food products caused by insects annually i n the United States amounts to $2,000,000,000. The insecticide industry i n the 52
AGRICULTURAL CONTROL CHEMICALS Advances in Chemistry; American Chemical Society: Washington, DC, 1950.
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ABRAMS—PUBLIC HEALTH ASPECTS OF AGRICULTURAL CHEMICALS*
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United States has a total value of about $15,000,000. I n 1948, 35,000,000 pounds were produced of one insecticide a l o n e — D D T (9). There are about 25,000 plant diseases i n the United States, including 10,000 of economic importance, and these cost the nation about $4,000,000,000 a year. The annual wholesale value of a l l agricultural chemicals i n the United States is about $185,000,000. The Bureau of Chemistry of the State Department of Agriculture i n California reported during the fiscal year 1946-47 the registration of 7717 economic poisons. Pesticides are only one group of chemicals i n use i n agriculture. There are now hormones either to accelerate or retard the growth of plants. Livestock are being fattened with the aid of chemicals. Soil and seeds are treated with chemicals. New fertilizers are being developed. M a n y other applications are being discovered. A t the outset, one must note the fact that the public health values of the agricultural chemicals far outweigh the health hazards i n their use. The conquest of the insect-borne plagues with the aid of insecticides can now be foreseen. Agricultural chemicals make possible greatly increased production and preservation of food. The Malthusian philosophy of starvation is being discredited effectively with the aid of modern chemistry. Society can and should use the agricultural chemicals with complete safety to health. It can be assumed that almost any material that is poisonous to insects is poisonous to man, the main variables being the dose and relative susceptibilities of the species. The agricultural chemicals, like other chemicals, reach the body b y inhalation, ingestion, and contact with the skin and mucous membranes. They may cause acute and chronic diseases which vary from superficial skin and mucous membrane inflammations to serious and sometimes fatal systemic conditions. Other speakers on this program describe the toxicological and pharmacological action of various of these poisons. I t is appropriate, however, that a representative of a public health department should discuss the public health aspects. When illness and death occur as a result of overexposure to these poisons, the public health industrial hygienist is called upon to investigate and devise controls. The Bureau of A d u l t Health of the California State Health Department has i n recent years investigated and devised controls for a great variety of economic poisons. These include fumigants such as methyl bromide and the cyanides, preservatives such as sulfur dioxide, the pesticides, and others such as ethylene chlorohydrin used to accelerate the sprouting of seed potatoes. F r o m another aspect, the Bureau of Food and Drugs, also a part of the State Health Department, is vitally interested i n the prevention of adulteration of foods by these poisons. I t is essential today that the public health agencies cooperate very closely with the agricultural agencies, the farmer, the manufacturer of chemicals, and others concerned i n the proper handling of this problem.
Hazards to Public Health The arsenicals are today not the public health problem they once were. However, many lessons were learned from the experience with them. I n 1940, the U . S. Public Health Service reported its study on the effect of lead arsenate exposure on orchardists and consumers of sprayed fruit (8). I t found, i n a large group of consumers of the apples treated with lead arsenate, that there was a slight increase in the amount of lead and arsenic i n the blood and urine, although no harmful effects from this could be demonstrated at that time. However, lead arsenate constituted a definite health hazard to sprayers i n the apple orchards of Washington (1). The U . S. Public Health Service investigators (8) stated, "Although sprayers who apply lead arsenate spray intermittently did not appear to be adversely affected, top consideration should be given to the protection of the health of men who mix or apply lead arsenate sprays every working day of the season." They recommended that protective equipment be provided for mixing tanks at which people work on a full-time basis. Other investigators recommended also that the orchard industry set up an " a u t h o r i t y " with responsibility for providing an adequate health protection program for orchard workers (1). These recommendations apply essentially to similar operations for any of the economic poisons. AGRICULTURAL CONTROL CHEMICALS Advances in Chemistry; American Chemical Society: Washington, DC, 1950.
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ADVANCES IN CHEMISTRY SERIES
W i t h the exception of nicotine, the agricultural chemicals derived from plants are probably among the least hazardous to man (6). Nicotine itself is one of the most efficient insecticides. Nicotine can cause serious poisoning or death if swallowed, inhaled, or ab sorbed through the skin. The halogenated hydrocarbons comprise the largest significant group of pesticides. M o s t extensive investigation of toxicology has been done with D D T and i t illustrates well the ramifications of a public health problem with agricultural chemicals. D D T can cause toxic manifestations by any route of administration, and a number of cases of poisoning have been reported when large amounts of the material have been ingested. I t is possi ble, too, that many reported cases of D D T poisoning were i n reality caused b y the solvent in which the material was prepared rather than b y the active insecticide itself. B u t a more important health aspect of D D T is the fact that it is stored i n the body fat at a level four to ten times that of the dietary intake. It is secreted i n the m i l k of cows, goats, dogs, and rats (2). Other animals fed this milk show toxic symptoms. The D D T i n the milk appears to be concentrated i n the butterfat portion and therefore is transferred to the butter. So today the American people are consuming D D T i n their m i l k and butter as well as i n other agricultural produce. This may be especially important i n the case of infants and children because of their high consumption of milk. I n animals the w i t h drawal of food with consequent consumption of body fat produced characteristic D D T nervous symptoms. This effect might be important i n cases of human starvation or i l l ness i n which there is an appreciable storage of D D T i n the body. Howell (4) recently re ported finding 17 p.p.m. i n a lipoma removed from an individual who had worked with D D T and ingested it i n milk and other foods over a period of about four years. N o clinical effects were noticed i n the patient. One can only speculate on the possible hazard should such an individual be forced b y starvation or illness to metabolize his body fat.
Organic Phosphates These observations have motivated the U . S. Department of Agriculture and Bureau of Food and Drugs recently to take steps banning the use of D D T i n spraying of dairy barns and of dairy and meat cattle. The organic phosphates are the newest large group of insecticides, the major com pounds being tetraethyl pyrophosphate and parathion. These have all been shown to be extremely poisonous to animals, and i n the brief period i n which they have been used they have demonstrated their toxicity to human beings. I n the first half of 1949, there were at least five fatalities reported, one i n California. Persons exposed to these materials may display marked contraction of the pupils to the point of blindness, shortness of breath with a feeling of tightness of the chest, headache, and other symptoms depending upon the severity of exposure. These effects result, i n part at least, from the destruction of cholinesterase b y parathion with consequent building up in the body of excessive amounts of acetylcholine. Because the phosphates are readily absorbed through the skin and are hazardous from exposure b y any route, prevention of poisoning includes avoiding contact with the bare skin and avoidance of inhalation of the chemicals. I t is recommended also that workers change their clothes completely and bathe with soap and water after every use of this material. Particular caution is indicated on the part of pilots engaged i n airplane spraying because of the effects of the organic phosphates on the eyes. Parathion presents special problems because of its translocation into the plant. The agricultural chemicals i n general are more dangerous to handle i n solution than i n wettable powder or dust form. Parathion and nicotine are the only exceptions to this as they seem to be about equally toxic i n wet or dry form. One overriding problem is the lack of knowledge concerning the effects of exposure to small amounts of these chemicals over a long period of time. Cancer must be regarded as a possible hazard i n the handling of some of the agricultural chemicals and the solvents i n which they are prepared. Cancer of the skin has been reported i n persons i n contact with arsenicals used i n fruit spraying and sheep dipping (3, δ). Multiple organ malignancies AGRICULTURAL CONTROL CHEMICALS Advances in Chemistry; American Chemical Society: Washington, DC, 1950.
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were observed i n animals exposed to 2-acetaminofluorine, a material originally under i n vestigation for use as an insecticide (10).
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Public Health Program for Control of Economic Poisons A well planned public health program is needed for the safe exploitation of the agricultural chemicals. Such a program should embody the following major features : Research. M a n y economic poisons are released on the market prior to adequate research i n their toxicity. Too often human injury is the stimulus to research which should have been done before the material was used. There is need for the training of more personnel i n the fields of toxicology, pharmacology, and occupational health. There is an u r gent need for the augmentation and improvement of present research facilities. There is a need for the better coordination and free exchange of information between private and public research groups. A l l the above could be greatly facilitated b y the establishment of a national science foundation with adequate financial support and broad representation of the groups concerned. Cooperation of Private and Public Agencies. The federal, state, and local public health agencies, the agricultural agencies, and the chemical manufacturers and distributors should maintain a close liaison for the exchange of information and the prompt promulgation of public education and control measures. Legal Controls. These include a labeling law requiring a l l economic poisons to be clearly labeled according to content and amount of each ingredient, with appropriate statements on first aid measures and precautions; and an adequate system of inspection for the presence of poisonous residues on the surface of, or within, the foods placed on the market. It is recommended also that the states adopt legislation consistent with the federal laws. Education i n the occupational health a n d consumer health aspects must be extended. Public health agencies in collaboration with the agricultural and food and drug manufacturers' agencies should disseminate appropriate educational material for farmers and allied workers, for the employees engaged in handling and manufacturing economic poisons, for the medical and allied professions, and for the public generally. Literature Cited (1) Farner, L . M . , Yaffe, C. D., Scott, N . , and Adley, F . E., J. Ind. Hyg. Toxicol., 31, 162 (May 1949). (2) Fitzhugh, O. G., Ind. Eng. Chem., 40, 704 (1948). (3) Franseen, C. C., and Taylor, G. W., Am. J. Cancer, 22, 287 (1934). (4) Howell, D. E., paper presented before Oklahoma Academy of Science, 1949. (5) Hueper, W. C., "Occupational Tumors and Allied Diseases," p. 17, Springfield, Ill., C. C. Thomas, 1942. (6) Lehman, A . J . , "Toxicology of the Newer Agricultural Chemicals," U . S. Food and Drug Administration, Washington, D . C., 1948. (7) Mott, F., and Roemer, M . , "Rural Health and Medical Care," New York, McGraw-Hill Book Co., 1948. (8) Public Health Service, Bull. 267 (1941). (9) Webster, R. L . , State College of Washington, Circ. 64 (December 1948). (10) Wilson, R. H . , DeEds, F., and Cox, A . J., Jr., Cancer Research, 1, 595-608 (1941).
AGRICULTURAL CONTROL CHEMICALS Advances in Chemistry; American Chemical Society: Washington, DC, 1950.
