WASTES IX RELATION TO AGRICULTURE AND FORESTRY 



49 



Malaria 



Filariasis 



Urban yellow fever 



Dengue 



Virus ( ncephalitis 



Lotise-borne typhus 



Louse-borne relapsing 



fever 

 Trench fever 

 Plague 



Murine typhus 

 Cholera 

 Scrub typhus (tsutsuga- 



mushi ) 

 Rickettsialpox 



1 (ysentery and diarrhea 



Amebiasis 



Leishmaniasis 



Bartonellosis 



< )nchocerciasis 



Sandfly fever 



Trypanosomiasis 



Yaws 



Infectious conjunctivitis 



Chagas' disease 



s. ahies 



Tick-borne diseases: 



Relapsing fever 



Rocky Mountain spotted 

 fever 



Knipling (71) estimated that on a worldwide 

 basis over the first 10 years of use of the insecticide 

 DDT, 5 million lives were saved and 100 million 

 illnesses prevented. Flies, mosquitoes, lice, fleas, 

 and ticks constitute most of the vermin involved. 

 If only a fraction of the pests involved had their 

 spawning ground in rural areas, one cannot dis- 

 miss this class of infectious agents as being of sec- 

 ondary importance. 



Insects are also vectors of diseases afflicting trees 

 and shrubbery, lawns and gardens, and even pets of 

 urban and suburban residents. The source of the 

 vector or the infectious agents is often from agri- 

 cultural, forested, or rural areas. 



Agricultural Chemicals 



Pesticides, when used properly, have resulted 

 in great benefits to man and his surroundings. Con- 

 versely, when misused or used carelessly, they have 

 caused harm. On balance, the adverse effects have 

 been relatively minor in relation to the great bene- 

 fit- from pest control. 



Use of pesticides continues to increase. In 1964, 

 693 million pounds of these chemicals were sold 

 in the United Stales: 65 percent was used in for- 

 estry and agriculture. A study was made based on 

 a survey of farmers whose sales represented 90 

 percent of total agricultural srdes in the United 

 State, in VMM (11). Of the fanners surveyed. 94 

 percent used pest icides to some degree. These farm- 

 ers spont. $456 minion on pesticides in 19G-1. Sup- 

 plementary information indicates that fanners 

 wl) > operated small farms bill were not included 

 in the survey spent aboul $58 million on pesticides. 

 Thus expei 1. lit ure- for pesi icides bs all farmers in 

 196 1- amounted to$5] 1 million. 



Insecticides 



[nsecticides were applied to about 83 million 



acre- of land in L964. When these chemicals arc 



applied directly to the environment, i1 is obviou 

 impossible to avoid exposing most, if not all, of 

 the organisms in that environment to the insecti- 

 cide applied. Therefore, it is not always possible 

 to avoid hazards to many nonta anisms liv- 



ing in the same part of the environment treated for 

 insect control. These chemicals may then move 

 other parts of the environment not actually 

 treated. 



Organizations and individuals associated with 

 conservation and the preservation of wildlife have 

 alleged that nontarget organisms are unduly jeop- 

 ardized by the insecticide treatment. Obviously, 

 most insect problems are now being met by insecti- 

 cides; and many insecticides currently in use have 

 a broad spectrum of biological activity. It is not 

 surprising that a chemical agent that will kill a 

 harmful insect may also pose hazards to other 

 animal life. 



It is not possible with some current materials 

 to avoid the destruction of many kinds of beneficial 

 insects — and there are far more kinds of beneficial 

 than of destructive insects. Insect parasites and 

 predators are helpful in maintaining reasonable 

 population levels of some destructive insect-. 



It is likewise not always possible to avoid expos- 

 ing many other organisms such as fish, birds, mam- 

 mals, and other animals that may exist in culti- 

 vated fields, forests, orchards, rangelands, marshes, 

 lakes, or streams. "While these animals generally 

 are less likely to be adversely affected by insecti- 

 cides than beneficial or destructive insects are. sig- 

 nificant adverse effects have been noted under cer- 

 tain situations. 



The most complex and serious conseqiu 

 environmental contamination with insecticides in- 

 volve the phenomenon of biological magnification 

 of residue- in tissues of animals. This phenomenon 

 appear- to be limited to the fat soluble pesticides. 

 ( 'crtain organisms may beexposed for long periods 

 to low-level, persistent insecticides thai accumu- 

 late in body tissues. Thee a i umulations may not 

 cause measurable acute effects in tl >- ■ organisms. 

 However, through food chains the residues may 

 accumulate to higher and higher levels in tissues 

 of the succession of animals involved in the food 

 chain. 



In some instances, anill ' the to; 



(oo,{ cl ich as fish-eating birds, appear to 



have been killed through such insecticide res 



