Bulletin ILLINOIS ill I BULLETIN* n Pesticides and Environmental Quality in Illinois rt L. Metcalf s R. Sanborn ^^\m %\^^ 00^ '^^R^* >F ILLINOIS ITMENT OF REGISTRATION AND EDUCATION IRAL HISTORY SURVEY DIVISION NA, ILLINOIS Ml. cittK/^rtT OF THE OCT 3 1975 ,'N. . .. » Ot- ILLINOIS A' tJRBANA-CHAMPAIGN VOLUME 31, ARTICLE 9 AUGUST, 1975 ILLINOIS ra.tii.rail History Survey BXJLLETII^ '.irt L. Metcalf rzs R. Sanborn Pesticides and Environmental Quality in Illinois (OF ILLINOIS «TMENT OF REGISTRATION AND EDUCATION I TljRAL HISTORY SURVEY DIVISION »^NA, ILLINOIS VOLUME 31, ARTICLE 9 STATE OF ILLINOIS DEPARTMENT OF REGISTRATION AND EDUCATION BOARD OF NATURAL RESOURCES AND CONSERVATION Ronald E. Stackler, J.D., Chairman; Thomas Pauk, Ph.D., Uinlnriy, L. h. Sloss, Ph.D., GWojij/ ; Heiihert S. Gdtowsky PhD., Chemistry: Robert H. Anderson, B.S.C.E,, Engineering; W. L. Everitt, E.E., Ph.D., Itepre- senling the President of the University of Illinois; John C. Guvon, Ph.D., Representing the President of Southern Illinois University. NATURAL HISTORY SURVEY DIVISION, Urbana, SCIENTIFIC AND TECHNICAL STAFF George Sdrugel, Jr., Ph.D., Chief . Alice K. Adams, Seeretary to the Chief linois Section of Economic Entomology William H. Luckmann, Ph.D., Entomologist and Head Willis N. Bruce, Ph.D., Entomologist Wayne L. Howe, Ph.D., Entomologist Stevenson Moore, III, Ph.D., Entomologist, Extension James E. Applebt, Ph.D., Associate Entomologist Edward J. Armdrdst, Ph.D., Associate Entomologist Marcos Kogan, Ph.D., Associate Entomologist Joseph V. Maddojc, Ph.D., Associate Entomologist Ronald H. Meter, Ph.D., Associate Entomologist Robert D. Paosch, Ph.D., Associate Entomologist Ralph E. Sechriest, Ph.D.. Associate Entomologist John K. Bohseman, M.S., Assistant Entomologist George L. Godfrey, Ph.D., Assistant Entomologist Michael E. Irwin, Pli.D., Assistant Entomologist Donald E. Kuhlman, Ph.D., Assistant Professor, Extension RoscoE Randell, Ph.D., Assistant Professor, Extension William G. Rdesink, Ph.D., Assistant Entomologist .Tames R. Sanborn, Ph.D., Assistant Entomologist Douglas K. Sell, Ph.D., Assistant Entomologist C. Robert Taylor, Ph.D., Assistant Entomologist John L. Wedberg, Ph.D., Assistant Entomologist Clarence E. White, B.S., Assistant Entomologist Tim Cooley, M.A., Assistant Specialist, Extension Kurt E. Redborg, M.S., Assistant Specialist John F. Walt, M.S., Assistant Specialist, Extension Jean G. W^ilson, B.A., Supervisory Assistant Stephen Roberts, B.S., Junior Professional Scientist John T. Shaw, B.S., Junior Professional Scientist Daniel P. Bartell, Ph.D.. Research Associate Bettina Francis, Ph.D., Research Associate Margaret Anderson, B.S., Research Assistant Robert J. Barney, B.S., Research Assistant Tzu-SUAN Chu, M.S., Research Assistant Stephen D. Cowan, B.S., Research Assistant Stephen K. Evrard, B.S., Research Assistant Marion Farris, M.S., Research Assistant Bonnie Irwin, M.S., Research Assistant Jenny Kogan, M.S., Research Assistant Glenn Levinson, B.S., Research Assistant Rose Ann Meccoli, B.S., Research Assistant Brian Melin, B.S., Research Assistant Celia Shih, M.S., Research Assistant Kathy Wood, M.S., Research Assistant Jo Ann Auble, Technical Assistant Lowell Davis, Technical Assistant Charles G. Helm, M.S., Technical Assistant Linda Isenhower, Technical Assistant Lu-PiNG Lee, M.S., Technical Assistant Section of Botany and Plant Pathology Claus Gruxwald, Ph.D., Plant Physiologist and Head Robert A. Evers, Ph.D., Botanist' Eugene B. Himelick, Ph.D., Plant Pathologist R. Dan Neely, Ph.D., Plant Pathologist D. F. Schoeneweiss, Ph.D., Plant Pathologist J. Leland Crane, Ph.D., Associate Mycologist Walter Hartstirn, Ph.D., Assistant Plant Pathologist Betty S. Nelson, Jvnior Professional Scientist Gene E. Reid, Technical Assistant Section of Aquatic Biology D. HojiER Buck, Ph.D., Agnatic Biologist William F. Guilders, Ph.D., Aquatic Biologist R. Weldon Larimore, Ph.D., Aquatic Biologist Robert C. Hiltibran, Ph.D., Biochemist Allison Brigham, Ph.D., Assistant Aquatic Biologist Warren U. Brigham, Ph.D., Assistant Aquatic Biologist Richard E. Sparks, Ph.D., Assistant Aquatic Biologist Ted W. Storck, Ph.D., Assistant Aquatic Biologist John Tranquilli, Ph.D., Assistant Aquatic Biologist Mary Frances Bial, Junior Professional Scientist Carl M. Thompson, Junior Professional Scientist Richard J. Baur, M.S., Research Associate Donald W. Ddfpord, M.S., Research Associate John M. McNurney, M.S., Research Associate Harry W. Bergmann, B.S., Research Assistant Kurt T. Clement, B.S., Research Asitistant Larry W. Coutakt, M.S., Research Assistant Herbert M. Drbier, M.S., Research Assistant Michael A. Frakes, M.S., Research Assistant Thomas E. Hill, M.S., Research Assistant Earl Thomas Joy, Jr., M.S., Research Assistant Richard Kocher, B.S., Research Assistant Robert Moran, M.S., Research Assistant Katiiryn Ewing, B.S., Technical Assistant Susan Moore, Technical Assistant Florence Partenheimer, B.A., Technical Assistant C. Russell Rose, Field Assistant Section of Faunistie Surveys and Insect Identification Philip W. Smith, Ph.D., Taxonomist and Head Wallace E. LaBerge, Ph.D., Taxonomist Milton W. Sanderson, Ph.D., Taxonomist Lewis J. Stannard, Jr., Ph.D., Taxonomist Larry M. Page, Ph.D., Assistant Taxonomist John D. Unzicker, Ph.D., Assistant Taxonomist Donald W. Webb, M.S., Assistant Taxonomist Bernice p. Sweeney, Junior Professional Scientist Craig W. Ronto, Technical Assistant Section of Wildlife Research Glen C. Sanderson, Ph.D., Wildlife Specialist and Head Frank C. Bellrose, B.S., Wildlife Specialist Jean W. Graber, Ph.D., Wildlife Specialist Richard R. Graber, Ph.D., Wildlife Specialist Harold C. Hanson, Ph.D., Wildlife Specialist Ronald F. Labisky, Ph.D., Wildlife Specialist William L. Anderson, M.A., Associate Wildlife Specialist W. W. Cochran, Jr., B.S., Associate Wildlife Specialist William R. Edwards, Ph.D., Associate Wildlife Specialist . ,. . G Blair Joselyn, M.S., Associate Wildlife Specialist Charles M. Nixon, M.S., Associate Wildlife Specialist Kenneth E. Smith, Ph.D., Associate Chemist Richard E. Warner, M.S., Associate Wildlife Specialist Ronald L. Westemeieii, M.S., Associate Wildlife Specialist ,,., ^ . ,. , Stephen P. Havera, M.S., Assistant Wildlife Specialist David R. Vance, M.S., Assistant Wildlife Specialist Ronald E. Duzan, Junior Professional Scientist Helen C. Schultz, M.A., Junior Professional Scientist Eleanore Wilson, Junior Professional Scientist Sh.\ron Fradenburoh, B.A., Laboratory Technician Robert D. Cbompton, Field Assistant James W. Seets, Laboratory Assistant Section of Administrative Services Robert 0. Watson, B.S., Administrator and Head Supporting Services WiLJiA G. Dillman, Property Control and Trust Accounts Patty L. Duzan, Technical Assistant Robert O. Ellis, Assistant for Operations Larry D. Gross, Maintenance Supervisor Lloyd E. Huffman, Stockroom Manager J. William Lusk, Mailing and Distribution Service Jerry McNeae, Maintenance Supervisor Melvin E. Schwartz, Financial Records James E. Sergent, Greenhouse Superintendent Publications and Public Relations Robert M. Zewadski, M.S., Technical Editor Shirley McClellan, Assistant Technical Editor Lawrence S. Farlow, Technical Pliotographer Lloyd LeMere, Technical Illustrator Technical Library Doris F. Dodds, M.S.L.S., Technical Librarian Doris L. Sublette, M.S.L.S., Assistant Technical Librarian CONSULTANTS AND RESEARCH AFFILIATES: Systematic Entomology, Roderick R. IRwin, Chicago, Illi- nois; Wildlife Rese.arch, Willard D. Klimstra, Ph.D., Professor of Zoology and Director of Cooperative wiia- life Research, Southern Illinois University; Parasitology, Norman D. Levine, Ph.D., Professor of ] eterinar;, Parasitology, Veterinary Research and Zoology and Director of the Center for Human Ecology, University o, Illinois; Entomology, Robert L. Metoalf, Ph.D., Professor of Zoology and of Entomology^ ^"'"^'''''^iJL "Tw and Gilbert P. Waldbaubr, Ph.D., Professor of Entomology, University of Illinois; °""'° Norton, Ph.D., Professor of Statistical Design and Analysis, University of Illinois. Statistics, Horace W, CONTENTS Acknowledgments 33I Use of Pesticides _ 3S1 Need for Sur\'eillance 382 Benefit-Risk of Pesticide Use 383 E.\kly-Waening Technology 383 Model-Ecosystem Technology 385 Herbicide Test Results , _ 386 Organophosphorus Insecticide Test Results 389 Carbamate Insecticide Test Results 392 Miscellaneous Inseciicide Test Resltlts 393 Organochlorine Insecticide Test Results 394 Environmental Persistence 395 Fungicide Test Results 399 Discussion 400 Biological Effects 400 Degradative Products 400 Ecological Magnification 401 Unextractable Radioactive Materials 402 Literature Cited .— . 433 Index 436 This report is printed by authority of the State of Illinois, IRS Ch. 127, Par. 58.12. It is a contribution from the Section of Economic Entomology of the Illinois Natural History Survey. Robert L. Metcalf is Professor of Biology and Research Professor of Entomology, University of Illinois. James R. Sanborn is an Assistant Entomologist, Illinois Natural History Survey. (66939—4M—S-75) Pesticides and Environmental Quality in Illinois Robert L. Metcalf James R. Sanborn ILLINOIS has 29,039,000 acres ( 1.18 X 10' ha) of farmland, amounting to 54 percent of its land surface. This land is among the most fertile and pro- ductive in the world, and Illinois ranks IS the second state, after California, in producing faiTn crops, valued at 53.167 bilhon in 1973. Illinois land produced 996,010,000 bushels (2.53 X 10" kg) of com (17.6 percent of the U.S. total), 290,745,000 bushels (7.9 X 10* kg) of soybeans (18.6 percent of the U.S. total), .37,800,000 bushels (1.03 X 10' kg) of wheat (2.2 percent Df the U.S. total), 19,780,000 bushels (2.88-10= kg) of oats (30 percent 3f the U.S. total), 3,251,000 tons (2.95 ^- 10' kg) of hay (2.4 percent of the U.S. total), and 4,225,000 pounds (1.92 X 10' kg ) of red clover seed ( 15 per- cent of the U.S. total). From these plant products Illinois produced an additional $1,906 billion worth of live- stock (4.2 percent of the U.S. total) (Illinois Cooperative Crop Reporting Service 1973). The value of Illinois farmland ex- ceeds $30 billion by current land value, and its corn crops alone have been valued at more than $30 billion over the past 100 years. However, in terms of its capability to help to feed a world which is growing ever hungrier, the value of Illinois soil can scarcely be overestimated. ACKNOWLEDGMENTS The research described in this report has been supported by a number of agencies, and portions of the data were obtained through the work of many individuals. Sponsors include the Her- man Frasch Foundation; American Chemical Society; Rockefeller Founda- tion; U.S. Environmental Protection Agency Grant EP-826 and Project R- 800736; U.S. National Science Founda- tion Grant GI-39843; U.S. Department of the Interior through the Illinois Water Resources Center Grants B-050 and B-070; World Health Organiza- tion; and Illinois Agricultural Experi- ment Station Regional Project NC-96. Individuals to whom particular thanks are due are Dr. Gary Booth, Dr. Dale Hansen, Dr. Asha S. Hirwe, Dr. Jorge Iwan, Dr. Inder Kapoor, Dr. Po-Yung Lu, Dr. Gurcharan Sangha, Dr. Ching- Chieh Yu, Margaret Anderson, Carter Schuth, and Patricia Sherman. Radiolabeled pesticides for evalua- tion were generously contributed by American Cyanamid, Badische Aniline Soda Fabrik Aktiengesellschaft, Chem- agro Corporation, Chevron Chemicals, CIBA-Geigy Corporation, Dow Chemi- cal, Eli Lilly and Company, EMC Cor- poration, Hercules Corporation, Mobile Chemical Company, Monsanto Com- pany, Morton Chemical Company, Na- tional Institutes of Environmental Health Sciences, Sobering Corporation, Shell Chemical Company, Thompson- Hayward Company, Union Carbide Chemicals, Upjohn Company, Velsicol Corporation, and Zoecon Corporation. USE OF PESTrCIDES Modern agricultural practices—in- volving superior plant varieties, im- proved cropping methods, heavy ap- plications of nitrogenous fertilizers, and extreme reliance on agricultural chemi- cals, especially herbicides and insecti- 381 382 Illinois Natural History Survey Bulletin Vol. 31, Art. 9 cides—have been responsible for the state's immense agricultural produc- tivity. These innovations have seen Illinois corn yields increase from 30 bushels per acre (1,601 kg per ha) in 1920 to 105 bushels per acre (6,605 kg per ha) in 1973. The use of pesti- cides in corn production has been de- scribed as being "as significant as the plow." Their use has increased phe- nomenally, and in Illinois more total acreage, more than 14 million acres (5.67 X 10' ha), is treated with pesti- cides than is treated in any other state (Fowler & Mahan 1972). In 1972 herbi- cides were applied to 14,326,000 acres (5.79 X 10' ha) (49 percent of Illinois farmland) and insecticides to 5,946,000 acres (2.41 X 10' ha) (20 percent of Illinois farmland) (Illinois Cooperative Crop Reporting Service 1973). On an acreage basis 14.7 percent of the herbi- cides and 14.1 percent of the insecti- cides used in U.S. agriculture were applied in Illinois although the state has only about 2.5 percent of the total cultivated land. We estimate (U.S. En- vironmental Protection Agency 1972a; Illinois Cooperative Crop Reporting Service 1973) that about 34 million pounds (1.54 X 10' kg) of the active ingredients of pesticides were applied to Illinois farm soil in 1971—equivalent to 1 pound for each acre (1.1 kg per ha) in the state or 3 pounds (1.36 kg) for each of the state's 11 million in- habitants. Much of the total amount of pesti- cides applied is dispersed throughout the environment (Frontispiece), enter- ing air, water, and food through vola- tilization and air currents, runoff and leaching, and uptake and concentration in food chains. NEED FOR SURVEILLANCE The heavy use of pesticides, chang- ing agricultural technology, and the rapid introduction of new pesticide products present a continuing demand for evaluation and surveillance of the effects of pesticides upon environmental quality. The long-term effects of widely used pesticides are not well appreci- ated. Thus, von Riimker and Horay ( 1972 ) , after a detailed survey of the most widely used pesticides, concluded that for 20 of the 35 compounds studied there was inadequate information about the nature of the environmental degra- dation products and their effects on en- vironmental quality. Considering that many of these pesticides, such as chlor- dane, toxaphene, dieldrin, propanil, captan, zineb, and maneb, were intro- duced 20 or more years ago, the mag- nitude of the problem is apparent. Furthermore, insect resistance to the organochlorine insecticides, together with increasingly severe effects of their use upon environmental quality, have resulted in their gradual replacement with organophosphorus and carbamate insecticides (Table 1). New pesticides are being introduced at a rate much faster than that of our scientific appreciation of their environ- mental effects. During the 30 years since World War II, the number of synthetic fungicides, herbicides, insecti- cides, nematocides, and rodenticides has increased from less than 100 to over 900. The scene changes constantly with the development of new products and new technologies such as no-till farming. During 1974, for example, the following new pesticides were introduced under experimental permit into Illinois agri- culture: cyprazine (Prefox®), metri- buzin (Sencor®), bentazon (Basa- gran®), oryzalin (Surflan®), pro- fluralin (Tolban®), dinitramine (Co- bex®), bifenox (MODOWN®), gly- phosate (Round-up®), Rowtate®, and Counter®. Pesticides introduced under such experimental permits may be used on hundreds of thousands to millions of acres of Illinois soil in a few years. Thus, carbofuran, introduced in 1968i was used to treat 706,000 acres (287,- 000 ha) in 1971, and trifluralin, intro- duced in 1964, was used to treat 1,226,- 000 acres (496,000 ha) in 1971 (Petty &Kuhlman 1972). \ug., 1975 Metcalf & Sanborn: Pesticides and Envikonmental Quality 383 Table 1 .—Use of organochlorine insecticides on Illinois farms. Year II 384 Illinois Natural History Survey BuLLETiNr Vol. 31, Art. 9 widespread use of highly persistent organochlorine pesticides with little or no prior understanding of their fates in the total environment, has prompted both scientific and lay concern about a screening methodology which could serve as a simple early-warning system against potentially undesirable or haz- ardous effects of the large-scale use of new agricultiiral chemicals or com- binations of them. The wait-and-see system, followed in the use of aldrin, dieldrin, heptachlor, and chlordane and requiring a generation or more to dis- tinguish serious environmental pollu- tion, is demonstrably inadequate and has resulted in such disasters as the widespread contamination and seizure of milk supplies, the destruction of mil- lions of contaminated chickens, and the devastation of valuable fishing in- dustries. A recent comprehensive study. Pesti- cide Use on the Nonirrigated Crop- lands of the Midwest (U.S. EPA 1972a) recommended that "a massive, interdis- ciplinary research effort be mounted to clarify the environmental behavior of major pesticides which are expected to continue in use for the forseeable future." Information needed includes the fates of pesticides in the environ- ment after application; routes of me- tabolism, degradation, and disappear- ance; natures of the ultimate break- down products; effects of long-term exposure of ecosystems to low-level residues; and interactions with other chemicals in the environment. It will be necessary to establish an order of priority among products to be investi- gated in this fashion. The investigations reported here rep- resent an effort by the State of Illinois, through the Illinois Natural History Survey and the University of Illinois, to assume the responsibility for the comprehensive research so urgently needed on the total environmental fates of new pesticides. SORGHUM ESTIGMENE PHYSA Fig. 1 .—The laboratory model ecosystem used to evaluate the fates and environmental effects of radiolabeled pesticides on terrestrial and aquatic organisms, including sorghum, salt-marsh caterpillar, plankton, alga, snail, mosquito larva, and mosquito fish. Aug., 1975 Metcalf & Sanborn: Pesticides and Environmental Quality 385 MODEL-ECOSYSTEM TECHNOLOGY The development of model-ecosys- tem or microcosm technology ( Metcalf et al. 1971; Metcalf 1974) has provided a quick and sensitive laboratory tool for pro\iding answers to these ques- tions about environmental pollution by pesticides: 1. The nature of the biological ef- fects on non-target organisms 2. The nature of degradative path- ways and tlie magnitudes of deg- radative products 3. The bioconcentration and eco- logical magnification (EM) of parent compounds and degrada- tion products in living organisms 4. The quantitative estimation of persistence and biodegradability Basically, model-ecosystem evalua- tion uses radiolabeled pesticides to fol- low qualitatively and quantitatively the movement and degradation of the com- pounds from a terrestrial (farm) en- vironment into an aquatic (lake) en- vironment and to demonstrate the pas- sage of the parent compound and its transformation products through aquatic food webs. The experimental model is shown in Fig. 1 and consists of a 20-gallon aquarium with a sloping shelf of washed quartz sand entering a lake of 7 liters of standard reference water ( Freeman 1953 ) , which provides mineral nutrition for plankton, alga, snail, mosquito larva, and fish and for sorghum plants growing on the ter- restrial farm area. The water phase of the system is aerated, and the entire system is kept in an environmental plant growth chamber at 80" F (26.5°C) with a 12-hour diurnal cycle of 5,000 foot candles of fluorescent light. The radiolabeled pesticide to be tested is applied to sorghum plants, seeds, or to the soil of the system, using a realistic dosage of 1-5 mg per experiment, equivalent to 0.2-1.0 pound per acre (0.22-1.1 kg per ha). Ten last-instar salt-marsh caterpillars, Estig- mene aciea, are introduced to consume the treated sorghum plants, and the caterpillars and their excretory prod- ucts, leaf frass, etc., contaminate the lake portion of the model system. The radiolabeled products enter the vari- ous aquatic food chains, e.g., plank- ton ->- daphnia {Daphnia magna) ->- mosquito {Culex pipieii^) ->- fish (Gambttsia affinis) or alga (Oedo- goniiim cardiaciim) ->- snail (Physa spp.). The movement of the radiolabeled products from plants to lake are mea- sured by counting the radioactivity of duplicate 1-ml water samples by liquid scintillation at intervals of 1, 2, 4, 7, 14, 21, 28, and .33 days or whenever desii-ed. After the system has been in operation for 26 days, 300 mosquito larvae are added, and after 4 more days 50 are removed for analysis. The food chains are completed after 30 days by adding three mosquito fish, G. affinis, \\'hich are left for 3 days to eat the daphnia and mosquito larvae. The experiment is terminated after 33 days, when weighed samples of the various organisms are homogenized in small volumes of acetonitrile. Aliquots are counted for total radioactivity by liquid scintillation. One liter of water from the system is extracted three times with diethyl ether to measure total radioactivity. The residual water is hydrolyzed with 1.0 IV hydrochloric acid for 4 hours and reextracted with diethyl ether to determine the conju- gated materials, and the amount of un- extractable radioactive materials is de- termined by counting the radioactivity of the remainder. The acetonitrile extracts of the or- ganisms are concentrated to a few milli- liters and known volumes are applied to thin-layer chromatography (TLC) plates of fluorescent silica gel (E. Merck GF-254). TLC is carried out with appropriate solvents (identified in the tables) and with the incorporation of standard known metabolites of the pesticide under study. After the chro- 386 Illinois Natural History Survey Bulletin Vol. 31, Alt. 9 inatograms are developed, they are placed against X-ray film and exposed for several weeks to several months to determine the areas containing radio- labeled products. These areas are scraped into scintillation vials, and scin- tillation counts are made to determine the amounts of individual degradation products present. The residues from the tissue extractions are combusted to determine the amount of unextractable radioactive materials, using either the Schoeniger oxygen flask technique (Kelly et al. 1961) or a tissue solubili- zation method. After the completion of these assays, the results of the experiment are as- sembled on balance sheets showing the amounts and natures of radiolabeled degradation products present. Wher- ever possible, the chemical identities of the degradation products are de- termined by cochromatography with known model compounds, by the use of specific microchemical reactions and by infrared and mass spectrometry. The results of such studies on 48 pesti- cides are shovioi in the tables. HERBICIDE TEST RESULTS The importance of examining the fates of herbicides in a terrestrial- aquatic model ecosystem cannot be overestimated, especially in view of the exponential growth in the use of herbi- cides over the past 20 years in the United States. Pimental et al. (1973) estimated that in 1945 the use of herbi- cides for controlling weeds in corn was practically nonexistent. However, in the 25-year period from 1945 to 1970 the use of herbicides increased significantly, and it was estimated that by 1970 herbicide treatment averaged 1 pound of active ingredient per acre (1.1 kg per ha ) . Though figures were not avail- able for 1945, it is possible to examine figures for 1950-1970, which clearly demonstrate that herbicide use on corn increased at least twentyfold during that time. Alachlor, or 2-chloro-2', 6'-diethyl- A'-(methoxymethyl)-acetanilide, is a member of a large class of chloro- acetanilide herbicides used to control annual grasses in cornfields and certain broadleaf weeds in corn or soybeans. The data clearly indicate the suscepti- bility of this herbicide to extensive degradation, as no residues of alachlor were isolated from any of the test organisms (Table 2). The high degree of degradation is further evidenced by the large number (10) of radiolabeled products of alachlor isolated from the water section of the ecosystem. Con- tinued use of this herbicide should not lead to its accumulation in aquatic food chains. Atrazine, or 2-chloro-4-(ethylamino)- 6- ( isopropylamino ) -s-triazine, is one of the most extensively used herbicides for controlling weeds in corn plantings. The alga, snail, and fish of the model ecosystem contained 2.4059, 0.2386, and 0.3511 ppm, respectively, of atrazine ( Table 3 ) . The percentages of atrazine in the radioactive materials extractable from the alga, snail, and fish were 87.3, 63.1, and 59.3, respectively. The EM values for atrazine for the alga, snail, and fish were 75.6, 7.5, and 11.0, re- spectively. In addition, the alga, snail, and fish contained smaller amounts, 0.2100, 0.05479, and 0.07356 ppm, re- spectively, of N-dethylatrazine (com- pound A, Table 3). Another N-deal- kylated product, N-deisopropylatrazine (compound B, Table 3), was isolated from the alga (0.04934 ppm), snail (0.02796 ppm), and fish (0.05496 ppm). The EM values of these two dealkylated metabolites were of the same order of magnitude as that ob- served for atrazine. Continued use of atrazine would not appear to lead to major accumulations in aquatic food chains. Bentazon, or 3-isopropyl-lH-2,l,3- J| benzothiadiazin-4- ( 3H ) -one-2,2-diox- M ide, is a new herbicide employed for the control of a selected number of broadleaf and sedge weeds. In the Aug., 1975 Metcalf & Sanborn: Pesticides and Environmental Quality 387 model ecosystem (Booth et al. 1973) it was susceptible to degradation, as indicated by the lack of residues in all organisms except the clam, which con- tained 0.622 ppm of iV-isopropylanthra- nilamide, 1.266 ppm of anthranilic acid, and 0.510 ppm of unchanged bentazon ( Table 4 ) . The percentage of bentazon in the radioactive materials extractable from the clam was 18,7, and the EM value was about 10. Continued use of this herbicide should not lead to its ac- cumulation in aquatic food chains. Cyanazine, or 2-chloro-4-(l-cyano-l- methylethylamino ) - 6-eth>'lamino-.s-tria- zine, is used for the control of annual grasses and broadleaf weeds in corn- fields. The beha\aor of this herbicide in the model ecosystem indicates that it is susceptible to degradation, as only the water plant, Elodea, contained resi- dues of this herbicide (Table 5). Neidier the fish nor the snail contained residues of c\anazine or its degradation products. The high water solubility, 171 ppm, of cyanazine and its apparent susceptibility to degradation clearly demonstrate that the continued use of cyanazine should not result in its ac- cumulation in aquatic food chains. Dicamba, or 3,6-dichloro-o-anisic acid, is an effective herbicide for the control of both annual broadleaf weeds and grasses in corn. The data indicate clearly that this herbicide is not ab- sorbed by the organisms of the model ecosystem ( Yu et al. 1975fl ) ( Table 6 ) . This fact is probably related to the pH of the aqueous portion of the model ecosystem, which is higher than the pKa (dissociation constant) of this benzoic acid derivati\'e; therefore, the herbicide exists in the ionic form. Dicamba in the ether-extracted water constitutes about 90 percent of the ex- tractable radioactive materials. Al- though the data do not indicate it, dicamba was reco\'ered from the water only after acidification and heating for 24 hours. It is impossible to state whether the dicamba was in the ionic form and that acidification facilitated the partition of dicamba into ether, or whether the dicamba was present as a conjugate and that the acid treatment broke dow n the conjugate and released the free acid. In any case, very little happened to dicamba in the water of the model ecosystem other than con- jugation through the carbonyl moiety. Phenmedipham, or methyl j>i-hy- drox\'carbanilate ?)i-methylcarbanilate, is a postemergence herbicide used in sugar beets to control a large variety of annual weeds. The fate of phen- medipham in this model ecosystem clearly indicates the susceptibility to degradation of this herbicide, as none of the organisms contained phenmedi- pham residues (Table 7). The radio- active material extractable from the fish remained at the origin of tlie TLC plate, indicating the polar nature of the radioactivity. The continued use of phenmedipham should not lead to its accumulation in aquatic food chains. 2,4-D, or 2,4-dichlorophenoxyacetic acid, is one of the oldest synthetic herbicides in use today. After more than 30 years of its continued use, prob- lems relating to aquatic food-chain ac- cumulation of 2,4-D are nonexistent. The data from the experiment with "'C-2,4-D corroborate the "outdoor" data that have accumulated for the past three decades, as no 2,4-D residues were found in any of the organisms of the model ecosystem (Table 8). As might be expected, the alga contained the greatest number of unidentifiable "C residues even though eight standard degradation products of 2,4-D were cochromatographed. Continued use of 2,4-D does not appear to lead to en- \ironmental problems relating to its accumulation in aquatic food chains. "Real-world" data and model ecosystem results are similar and clearly demon- strate the ability of this microcosm to predict potential enxironmental prob- lems. Propachlor, or 2-chloro-N-isopro- p\'lacctanilide, is one of a large number of a-chloroacetanilide herbicides, which 388 Illinois Natural History Survey Bulletin Vol. 31, Art. 9 include alachlor, that are used to con- trol annual grasses and some broadlcaf weeds in a number of crops including corn and soybeans. The structural simi- larity of propachlor to alachlor and its great susceptibility to degradation are evident, as none of the organisms con- tained residues of this herbicide ( Table 9). There was a very minute amount of propachlor (0.0564 ppb) in the water at the end of the experiment. Clearly the a-haloacetanilides are some of the most degradable herbicides ex- amined in this system, and continued use of these herbicides should not lead to their accumulation in aquatic food chains. Pyrazon, or 5-amino-4-chloro-2- phenyl-3- ( 2H ) -pyridazinone, is used for the control of annual broadleaf weeds in sugar beets and beets. The model ecosystem data clearly demon- strate that pyrazon is susceptible to degradation, as only the crab contained residues ( 0.476 ppin ) of this herbicide, which constituted 95.4 percent of the radioactive materials extractable from the crab (Table 10). The EM value for the pyrazon in the crab was 22.5 (Yu et al. 1975b). Continued use of this herbicide would not appear to lead to problems related to accumulations of it in aquatic food chains. Trifluralin, or a,a,a-trifluoro-2, 6-di- nitro-A',/V-dipropyl-p-toluidine, is used to control grasses and several broadleaf weeds in soybeans, cotton, and many other crops. Only the snail and fish contained 5.046 ppm and 0.261 ppm, respectively, of trifluralin as an ex- tractable residue (Table 11). The percentages of trifluralin in the ex- tractable radioactive materials in the snail and fish were 75.7 and 34.0, re- spectively. The EM values for the snail and fish were 17,872 and 926, re- spectively. In addition to trifluralin the snail contained lesser amounts of a,a, a-trifluoro-2,6-dinitro-N-propyl - p - tolui- dine (0..337 ppm), which had an EM value of 3,874. Trifluralin is the only herbicide tested that showed a pro- pensity to accumulate in either tlie fish or snail. Its tendency to accumulate is undoubtedly related to its low water solubility (0.58 ppm) and high hpid solubility (Probst & Tepe 1969). De- spite the accumulation in the snail and fish, trifluralin is unusual in that it is susceptible to degradation, form- ing at least 11 degradation products in water, yet demonstrates a tendency to be magnified to some extent through aquatic food chains. It is not, however, magnified at the level of chlorinated hydrocarbons, but at a level very similar to that of the insecticide methoxychlor, which has an EM value of about 1,500. Metrabuzin, or 4-amino-6-?e»t-butyl- 3 - ( methylthio ) as - triazin - 5 - ( 4H ) -one, is a new herbicide used for weed con- trol in soybeans. The data in Table 12 clearly demonstrate the degradability of this herbicide in the model ecosys- tem, as no residues of this herbicide were isolated from the organisms. Fur- ther, the water contained numerous metabolites, which is indicative of the susceptibility of this herbicide to degra- dation under the conditions of this ex- periment. The major degradation prod- uct in the water is a mixture of DK and DADK, which were not resolvable by thin-layer chromatography. The data from this system clearly indicate that the continued use of this herbicide should not lead to its accumulation in aquatic food chains. Bifenox, or methyl-5-(2',4'-dichloro- phenoxy ) -2-nitrobenzoate, is a new pre- emergence herbicide somewhat related to 2,4-D. As shown in Table 13, bi- fenox is degraded by hydrolysis of the methyl ester to form the parent benzoic acid (compound B, Table 13), and by reduction of the nitro group to the cor- responding amino compound (com- pound A, Table 13). There was no evidence of cleavage of the diphenyl ether moiety. Bifenox is of low water solubility ( 0.35 ppm ) ( Fig. 2 ) and was bioconcentrated about 200-fold by the Aug., 1975 Metcalf & Sanborn: Pesticides and Environmental Quality 389 fish. It falls in the borderline area of moderate biodegradability and should be used with care. ORGANOPHOSPHORUS INSECTICIDE TEST RESULTS The decline in the use of organo- chlorine insecticides to control pest species ( Table 1 ) is the result of factors such as target-pest resistance, environ- mental hazards, and more recently, the ban imposed by the U.S. Environmental Protection Agency (EPA ) on DDT and aldrin dieldrin as general insecticides for home and agricultural use. Further, in view of the recent action of the EPA seeking to ban the use of chlordane, heptachlor, and heptachlor epoxide, it is certain that more phosphate and carbamate insecticides will be used to fill the void left by the elimination of the organochlorine insecticides. There- fore, it is essential to examine carba- mate and phosphate insecticides to insure that no problems of the environ- mental persistence and aquatic food- chain accumulations of these insecti- cides will occur. Chlorpyrifos, or 0,0-diethyl-0-(3,5, 6 - trichloro - 2 - pyridyl ) phosphorothio- nate, had EM values in the alga, snail, mosquito, and fish of 72, 691, 4.5, and 320, respectively. Of the radioactive material extractable from each or- ganism, the percentages of chloipyrifos isolated from the alga, snail, mostjuito, and fish were 30.3, 48.1, 7.9, and 49.5, respectively (Table 14). The position of the "C label in the pyridyl ring allows the investigation of the per- sistence of this moiety in the organisms of the s)stem or its uptake by them or both. The ecological magnification and percentage of the extractable radio- active materials for the pyridinol in each organism were: alga, 44, 18.8 percent; snail, 443, 32.3 percent; mos- quito, 191, 34.9 percent; and fish, 180, 29.1 percent. The absence of the oxon of chlorpyrifos in any of the organisms is typical, as the oxons of the phosphate insecticides were not found generally in any of the organisms. Chlorpyrifos-niethyl is an insecticide similar to chlorpyrifos except for the substitution of 0,0-dimethyl for 0,0- diethyl groups to yield 0,0-dimethyl-0- ( 3,5,6-trichloropyridinyl ) phosphorothi- onate. The chlorpyrifos-methyl ecologi- cal magnification values for the alga, snail, mosquito, and fish are 478, 544, 1,875, and 95, respectively. The values for the snail and fish are substantially lower than those found in the organisms subjected to chlorpyrifos, the result of the greater susceptibility of tlie O- methyl groups to degradation as com- pared to that of the O-ethyl moieties in chlorpyrifos. The percentages of chlor- pyrifos-methyl in the radioactive ma- terials isolated from the alga, snail, mosquito, and fish were 49.0, 49.3, 68.2, 20.7 percent, respectively (Table 15). Again, because the "C label is located in the pyridyl moiety, it is possible to investigate the fate of this group in the model ecosystem. The ecological magnification and percentage of the chlorinated pyridinol in the organisms were: snail, 41, 9.3 percent; fish, 54.5, 29.7 percent. As was observed for chlorpyrifos, none of the organisms contained the activation product, chlor- pyrifosoxon-methyl. Counter® is one of the newer phos- phate insecticides under development for use as a soil insecticide, and it has the chemical name of 0,0-diethyl S- (fgrf-butylthio) -methyl phosphorodi- thioate. This insecticide was therefore applied in the sand of the model eco- system to mirror its use in the field. The similarity in structure to phorate (Thimet®) and disulfoton (Di-Sys- ton®) is obvious, and the degradation in pathways of sulfur oxidation in tire side chain of Counter® was similar to those of the other two pesticides. The percentages of Counter® in the radio- active materials extractable from the alga, snail, mosquito, and fish were 3.3, 23.5, 4.7, and 25.0, respectively (Table 390 Illinois Natural History Survey Bulletin Vol. 31, Art. 9 16). No other metabolites were iso- lated from the fish or mosquito although a small amount (0.0241 ppm) of Counter® oxon was observed in the snail. The Counter® ecological mag- nification values from the alga, snail, mosquito, and fish were 175, 1,830, 360, and 535, respectively. These values from the fish and snail are somewhat higher than those found for most other phosphate insecticides. Undoubtedly these higher values are related both to the initial stability of the phosphoro- dithionate and to the application of this chemical to the sand, which does not allow for the initial metabolism and degradation by the caterpillars. The water sector of the ecosystem contained only trace amounts of Counter® and of nearly all of the possible combina- tions of the oxidation products of phos- phorothioate and sulfide sulfur. Temephos (Abate®), or the bis-0,0- dimethylphosphorothioate ester of 4,4' dihydroxydiphenyl sulfide, is an excel- lent mosquito larvicide and appears to possess ideal environmental charac- teristics, as it is exceptionally degrad- able. No residues of temephos or any of its oxidative or hydrolytic metabo- lites occurred in the fish. Because of its high larvicidal activity, the mos- quitoes were killed throughout the usual duration of the experiment, and it was extended to 53 days. The alga and snail contained small amounts (0.00195 and 0.01876 ppm, respec- tively) of temephos (Table 17). The EM values of temephos from the alga and snail were 1,500 and 14,431, re- spectively. In addition, the alga con- tained small amounts (0.4-2.0 ppb) of all of the cochromatographed metabo- lites, and the snail contained substan- tially fewer of the metabolites though at somewhat higher concentrations ( 2-27 ppb ) . The higher concentrations in the snail again emphasize the low titer of enzymes in this organism ca- pable of degrading foreign compounds. The absence of data for the mosquito emphasizes the outstanding larvicidal properties of this insecticide. Fonofos (Dyfonate®), or O-ethyl- S-phenyl ethylphosphonodithioate, is an effective soil insecticide which is finding increasing use as a replacement for the organochlorine insecticides. Although the organisms of the model ecosystem contained small amounts of the unchanged fonofos, none con- tained significant amounts of degrada- tion products (Table 18). The per- centages of fonofos in the radioactive materials extractable from the alga, snail, and fish were 32.1, 27.0, and 80.5, respectively. Further, the fonofos in the alga, snail, and fish had EM values of 108, 86, and 77, respectively. The large number of degradation prod- ucts isolated from the water (14), coupled with the very low EM values, clearly indicates that fonofos does not accumulate significantly in aquatic food chains. Fenitrothion, or 0,0-dimethyl-0-(3- methyl-4-nitrophenyl ) phosphorothio- nate, is one of the safest organophos- phorus insecticides, as the LD^o for the rat is 500 mg per kg and for the mouse is 1,200 mg per kg. The substi- tution of the methyl group in the meta position of the nitrophenyl ring of methyl parathion is believed to be re- sponsible for the much reduced mam- malian toxicity as compared to that of methyl parathion, of which the LD.r,„ for the rat is 13 mg per kg and for the mouse is 75 mg per kg. Fenitrothion EM values of 349, 2.2, and 9.8 were found for the alga, mosquito, and fish, respectively. The percentages of feni- trothion in the radioactive materials isolated from the alga, mosquito, and fish were 33.7, 6.6 and 44.4, respectively (Table 19). The only other degrada- tion product isolated from the orga- nisms was a small amount (5.7 ppb) of fenitroxon found in the fish. This degradation product of fenitrothion had an EM value of 6.5. The isolation of this phosphorus oxon from the fish is Aug., 1975 Metcalf & Sanborn: Pesticides and En\ironmental Quality 391 unique, as none of the other oxons of the phosphate insecticides were found in the fish. Malathion, or 0,0-dimethyl-S-( 1,2- dicarl3oethoxyethyl)-phosphorodithio- ate, is widely used in the home and garden as an insecticide. It appears to be exceptionally degradablc, as no traces were found in any of the model- ecos\'steni organisms (Table 20). The fish, snail, and mosquito contained sev- eral uncharacterized metabolites, which were also found in the water. It is apparent that malathion is one of the most degradable organophosphorus in- secticides examined in this system. This degradability, together with malathion's low mammalian toxicity ( rat oral LD-,„ 1,300 mg per kg), makes it a safe and useful product. Acephate (Orthene®), or O-methyl- S-methyl-IV-acetylphosphoramidothio- ate, is a relati\ely new insecticide, which has found widespread use in the control of pests of \egetables. The parent insecticide was not isolated from any of the model-ecosystem organisms (Table 21), which is not unexpected in view of the high water solubility of acephate ( 650,000 ppm ) . Howe\ er, an uncharacterized degradation product was isolated (R, 0.93) in all of the organisms except the clam and fish. In the crab this degradation product had an EM value of 4,273 times the concentration in the water. Further research is in progress to determine the structure of this degradation product. Leptophos (Phosvel®), or 0-(4- bromo-2,5-dichlorophenyl ) -O -methyl phenylphosphonothionate, is a new or- ganophosphate insecticide now under- going extensive development for use in controlling pests of cotton and veg- etable crops. The available environ- mental degradation information ( Holm- stead et al. 1973; Aharonson & Ben-Aziz 1974) clearly indicates that this insecti- cide has a high degree of en\ironmental stability. Other problems with this in- secticide have been found in its use in Eg\pt on cotton, where it killed 1,300 water buffaloes (Shea 1974). Labora- tory experiments with chickens ha\'e shown that leptophos has neurotoxic effects (Abou-Donia et al. 1974). The behavior of leptophos in our model ecosystem indicates that it is one of the most persistent phosphorus- derixed pesticides examined (Table 22 ) . The experiment was extended to 45 days, because each time the mos- quitoes were introduced, they immedi- ately died. Even though the mosquitoes died after their introduction on the 45th day, the fish were then added to the ecos\stem, and the experiment was terminated 3 days later. Every organism contained residues of leptophos, the alga haxing 13.221 ppm, the snail 52.27 ppm, and the fish 1.559 ppm. These residues of leptophos in the radioactive materials extracted from the alga, snail, and fish constituted 41.8, 97.3, and 83.5 percent, respectively, of the totals. The EM values for leptophos were 12,243 for the alga, 48,398 for the snail, and 1,444 for the fish, respec- tively. Clearly, this is the most per- sistent organophosphorus insecticide ex- amined in the model ecosystem. Parathion, or 0,0-diethyl O-4-nitro- phen\l phosphorothionate, and methyl parathion, its 0,0-dimethyl analogue, were produced in the United States in 1970 in the combined amount of about 56 million pounds. The a\ailable in- formation on the behavior of parathion and methyl parathion in the en\'iron- ment indicates that they have presented no problems of accumulation in aquatic food chains after more than 25 years of widespread use. The model-ecosys- tem data (Table 23) corroborate the outdoor data. The only organism con- taining a residue of parathion was the fish, and there the concentration was only 0.1006 ppm, which constituted about 52 percent of the radioactixe ma- terials isolated from the fish. The ex- periment was lengthened to 38 days because of the toxicity of the water to 392 Illinois Natural History Survey Bulletin Vol. 31, Art. 9 tlie mosquito. The use of 2,6-"'C-la- beled 4-nitrophcnol-labclecl parathion allowed tlic examination of the fate of this moiety, and it was determined that tiie water (0.000136 ppm) and fish (0.0086 ppm) eontained small amounts of this moiety. CARBAMATE INSECTICIDE TEST RESULTS The carbamate insecticides recently ha\'e assumed a large role in Illinois agriculture with the elimination of the organochlorine insecticides because of the resistance of target pests, the en- \ironmental accumulative tendency of the organochlorine compounds, and their carcinogenic properties. The use of metalkamate, carbofuran, and car- baryl to control insect pests on corn and soybeans has proved to be effective and has eliminated the aquatic food chain accumulation problems of tlie formerly used chlorinated hydrocarbon insecticides. Metalkamate is a 3:1 mixture of m- ( I-ethylpropyl ) -phenyl and m- ( 1- methylbutyl) -phenyl N-methylcarba- inates introduced to control soil pests of corn. This insecticide does not have any tendency to accumulate in the higher members of the trophic web, though the alga (0.980 ppm); crab (0.0498 ppm), which died 7 days after the introduction of metalkamate; and Elodea ( 0.245 ppm ) contained residues of the parent compound (Table 24). These residues of metalkamate in the alga, crab, and Elodea constituted 55.0, 17.4, and 25.9 percent, respectively, of the extractable radioactive material from these organisms. The most inter- esting observation here is that these three organisms were the only orga- nisms that contained detectable amounts of "C. None of the other organisms had substantial amounts of '"C residues. While this insecticide has not been as effective recently as it has been in the past in controlhng pests of corn, its environmental behavior in the model ecosystem clearly indicates that should it become widely employed, no aquatic food chain accumulation problems are likely to arise. Carbaryl, or 1-naphthyl N-methyl- carbamate, was the first carbamate in- secticide to find widespread use in the home garden and in agriculture, and it is presently the most widely used insecticide in the United States. With the banning for general use of DDT in 1972, carbaryl is being used to con- trol the tussock moth in the Pacific Northwest; the gypsy moth, which is migrating westward from the eastern regions of the United States; and the spruce budwoiTii. After more tlian 20 years of widespread use, neither prob- lems of accumulations in food chains nor of ubiquitous food residues have been experienced. The data from the terrestrial-aquatic model ecosystem (Table 25) definitely corroborate the experience in the field, as no residues of carbaryl were found in any of the organisms. The water contained many degradation products of carbaryl, but no residues of carbaryl itself. Con- tinued widespread use of this insecti- cide will definitely not lead to prob- lems associated with accumulations in aquatic food chains. Carbofuran, or 2,2-dimethyl-2,3-di- hydrobenzofurany1-7-A/-methylcarba- mate, is an excellent soil insecticide for the control of corn and soybean pests. The behavior of this carbamate insecticide is similar to that of the other carbamates examined in that none of the organisms in the model ecosystem contained residues of the parent in- secticide (Table 26). The water con- tained a small amount of carbofuran (0.003889 ppm) as well as trace amounts of other metabolites and deg- radation products of carbofuran (Yu et al. 1974). It appears that the con- tinued use of this insecticide will not lead to environmental problems of ac- cumulations in aquatic food chains. Propoxur, or 2-isopropoxyphenyl N- methylcarbamate, is used for household Aug., 1975 Metcalf & Sanborn: Pesticides and Environmental Quality 393 pest control and for residual spraying for adult mosquitoes. In the model system every organism contained resi- dues of propoxur at concentrations of 0.0360, 0.0928, 0.4441, and 0.0468 ppm for the alga, snail, mosquito, and fish, respectively (Table 27). The percent- ages of propoxur in the radioactive ma- terials extracted from the alga, snail, mosquito, and fish were 7.8, 23.5, 19.4, and 39.9, respectively. The EM values for the alga, snail, mosquito, and fish are 112, 290, 1,388, and 146, re- spectively. In addition to the parent compound, the fish contained lesser amounts of 2-isopropoxyphenol (0.0252 ppm) and 2-isopropoxyphcnyl IV-hy- droxymethyl carbamate (0.0180 ppm). Propoxur was the only carbamate ex- amined in tliis model ecosystem tliat was accumulated by the fish. This fact may be, in part, related to the high specific activity of the radiolabeled propoxur ( 10.4 mCi/mM ) , which made it possible to determine the small resi- dues of this insecticide in the orga- nisms. Aldicarb is a systemic carbamate in- secticide, 2 -methyl -2-methylthiopropi- onaldoximyl N-methylcarbamate. Aldi- carb is readily oxidized in vivo to sulf- oxide and sulfone metabolites, both of which are insecticidal. These metab- olites and the parent compound form relatively persistent systemic toxicants in plant tissues (Metcalf et al. 1966). A single application to the roots of cotton plants kills boll weevil larvae during an entire growing season. There- fore, it was not unexpected to find these products persisting over the 33- day period of the model-ecosystem ex- periment (Table 28). However, the substantial water solubility of aldicarb, 0.6 percent, clearly prevented high bio- magnification in the organisms, and the EM value in the fish was 42. Aldicarb was highly toxic to the snail, Pliijsa, and all of these died early in the course of the experiment. Formetanate, or 3-dimethylamino- methyleneiminophenyl N-methylcarba- mate •hydrochloride, is a carbamate acaricide. As shown in Table 29, this compound is highly biodegradable, and no trace of the parent compound was found in the model ecosystem after 33 days. The only identifiable degrada- tion product (compound A, Table 29) involved removal of the iV-methylcar- liamoyl group and loss of the amidino moiety. We do not expect that this compound will cause problems in en- \'ironmental quality. MISCELLANEOUS INSECTICIDE TEST RESULTS Methoprene, or isopropyl-11-me- thoxy-3,7,1 1 -trimethyldodeca-2,4-dieno- ate, is one of the "fourth-generation" insecticides believed to interfere with tlie normal metamorphic development of insects. This pesticide has shown some promise in the control of mos- quitoes developing in irrigated fields in California. The degradation of metho- prene has been examined in detail in several outdoor systems ( Quistad et al. 1974 and 1975; Schooley et al. 1975). In the model ecosystem every orga- nism contained residues of methoprene (Table 30), with the alga containing 2.220 ppm, the snail 1.500 ppm, and the fish 0.0176 ppm. These methoprene residues in the alga, snail, and fish con- stituted 48.0, 30.7, and 25.1 percent, respecti\'ely, of the radioactive materials extracted from each organism. The EM values for methoprene in the alga, snail, and fish were 25,814, 17,442, and 205, respectively. Measurable amounts of the 1 1-O-demethylated methoprene were isolated from the alga, 0.723 ppm; snail, 0.469 ppm; and fish, 0.0181 ppm though the water contained none of this degradation product. Finally, the water, snail, and fish contained small amounts of ll-hydroxy-3,7,ll-trimethyl- dodeca-2,4-dienoic acid. Dimilin, or l-(2,6-difluorobenzoyl)- 3-(4-chlorophenyl) urea, is a recently introduced insecticide which apparendy interferes with the normal development 394 Illinois Natural History Survey Bulletln Vol. 31, Art. 9 of the insect cuticle and leads to mor- tality at molting. The use of two dif- ferent "C-labeled sites in dimilin en- abled us to examine the fates of the two phenyl moieties. Every organism contained this insecticide (Table 31), from the high of 13.1369 ppm in the mosquito in the "C-chlorophenyl urea dimilin to the low of 0.1097 ppm in the fish in the "C-difluorobenzoyl dimi- lin. Despite the variation in the ab- solute quantity of dimilin in the fish of the two experiments, 0.1097 ppm for the '"C-difluorobenzoyl and 0.3193 ppm for the '"C-chlorophenyl urea, the EM values of 19.2 and 14.5 were very close. The percentage of dimilin in the ex- traetable radioactive materials isolated from the fish was 6.7 percent for '^C- difluorobenzoyl dimiHn and 5.3 percent for '"C-chlorophenyl dimilin, indicating again close agreement in the data for the two '"C labels. While dimilin amounted to a small percentage of the extractable radioactive materials in the fish, the fractions of dimilin were con- siderably higher (46-98 percent) in the radioactive materials isolated from the rest of the organisms. Chlordimeform, or N-(4-chloro-o- tolyl ) -N,N-dimethyLforamidine, is one of the newer insecticides and appears to be effective in controlling cotton pests. In the model ecosystem only the snail contained residues of this insecti- cide, with a concentration of 0.0710 ppm (Table 32). The fraction of chlordimeform in the extractable radio- active materials isolated from the snail was about 40 percent. The water con- tained numerous breakdown products of chlordimeform, clearly indicating the lability of this insecticide in the model ecosystem. Banamite®, or benzoylchloride-2,4,6- trichlorophenylhydrazone, is a new pesticide that has found use on citrus for the control of mites (Table 49). Only the crab (0.0156 ppm), aquatic plant (0.041 ppm), and mosquito (0.0736 ppm) contained residues of this pesticide. The EM values for bana- mite in these organisms were 839 for the crab, 2,204 for the aquatic plant, and 3,957 for the mosquito. The amount of banamite in the extractable radio- active materials from these organisms ranged from 1 to 2 percent. Though neither the fish nor the snail contained residues of banamite, they contained an unidentified degradation product, designated II, that was magnified about 20,000 times in the snail and about 3,000 times in the fish. It does not ap- pear that continued use of this pesticide will lead to problems of aquatic food- chain accumulation, but perhaps more detailed analysis of the chemical struc- ture of some of the degradative prod- ucts should be undertaken. ORGANOCHLORINE INSECTICIDE TEST RESULTS The organochlorines, especially the cyclodienes aldrin, heptachlor, and chlordane, have been used extensively in Illinois since they were introduced in 1954 for the control of underground insect pests of corn, particularly the corn roolworms Dmbrotica longicornis and D. undecimpunctata howardi ( Big- ger & Blanchard 1959). Their use as soil treatments increased from about 125,000 acres (5.06 X 10" ha) treated in 1954 to a maximum of 5,601,572 acres (2.27X10' ha) treated in 1966 and slowly declined to about 2,100,000 acres (8.51 \ 10= ha) treated in 1974 (Petty 1974). The average treatment rate is about 1.6 pounds per acre ( 1.76 kg per ha ) of technical material for aldrin and 2.0 pounds (2.2 kg per ha) for heptachlor (U.S. EPA 1972a). It is estimated that over the 20-year period more than 82 million pounds (3.73 X 10' kg) of these chemicals have been applied to Illinois farm soils (Illinois Natural History Survey data ) . The ap- proximate farm acreages treated with the organochlorine insecticides in Illi- nois are presented in Table 1 (Illinois Cooperative Crop Reporting Service 1973). The use of cyclodiene insecticides in Illinois has been complicated by the Aug., 1975 Metcalf & Sanbohn: Pesticides and Environmental Quality 395 iiiN'asion of the western corn rootworm, D. vhgijeni, which now co\'ers nearly all of the coinland of Illinois and is totally resistant to the toxic action of aldrin, heptachlor, and chlordane (Petty & Kuhlman 1972), and by the unpredictability of attacks by the black cutworm, Agrotis ipsilon. ENVIRONMENTAL PERSISTENCE The organochlorine insecticides in use in Illinois are generally environ- mentally persistent or are readily con- verted to environmentally persistent compounds by photochemical or mi- crobial action or in vivo in the tissues of plants and animals. This is particu- larly true of the oxidation of aldrin to its 6,7-epoxide, dieldrin; heptachlor to its 2,.3-epoxide, heptachlor epoxide; and the cis- and f/aHs-chlordane isomers to oxychlordane. The axerage times required for 95-percent "breakdown" of these compounds in the soil has been estimated as: DDT, 11 years; dieldrin, 9.7 years; lindane, 6.7 years; chlordane, 4.2 years; heptachlor, 3.5 years; and aldrin, 2.5 years (Edwards 1965). Therefore, because of extremely heavy use patterns, it is no surprise to find that Illinois soils have been relatively highly contaminated by these com- pounds. The National Soils Monitoring Program (Carey et al. 1973) has re- ported these concentrations in Illinois soils: aldrin, 0.01-0.S3 (average 0.07) ppm; chlordane, 0.05-1.32 (average 0.09) ppm; dieldrin, 0.01-1.08 (aver- age 0.14) ppm; and DDT(T), 0.06- 0.12 (average >0.01) ppm. These resi- dues were among the highest found in the United States. DDT, or 2,2-bis-(p-chlorophenyl)- 1,1,1-trichloroethane, has the highest potential for bioaccumulation, 84,500- fold from water to fish, of any of the compounds studied ( Metcalf et al. 1971). This tendency to accumulate is the result of DDT's low water solu- bility (0.0012 ppm) and its environ- mental stability. DDT also accumulates because of its partial con\ersion b\' dehydrochlorination to DDE, 2,2-bis- ( p-chlorophenyl ) - 1 , 1 - dichloroethylene (water solubility 0.0013 ppm). In the fish at the top of the food chain DDT constituted 34.3 percent, DDE 53.9 percent, and DDD 9.8 percent of the absorbed total "C-radiolabeled material (Table 33). This fact demonstrates the gravest environmental flaw in the use of DDT, i.e., the conversion to and storage in animal lipids of the highly persistent DDE. DDE constituted 52.0 percent of the total radioactive ma- terials in the snail, 58.4 percent in the mosquito, and 54.0 percent in the fish. The percentage of unextractable radio- actixe materials in the various orga- nisms, a measure of total environmental stability, was low, ranging from 0.25 percent in the mosquito to 13.5 percent in the alga, and averaging 3.9 percent for all test organisms. As shown in Table 34, DDE in the model ecosystem was degraded slowly and showed high ecological magnification. Because of its persistence, degrada- tion to the even more stable DDE, bioaccumulation, and effectiveness in inducing mircosomal oxidase enzymes (Peakall 1970), DDT has been banned as an insecticide by both the U.S. and Illinois Environmental Protection Agen- cies. The high degree of bioconcentra- tion and the preponderance of storage as DDE found in the model ecosystem study are representative of the values found in nature, e.g., fatty tissues of humans in the USA contain an average of about 2.3-4.0 ppm of DDT and 4.3-8.0 ppm of DDE (Durham 1969). DDT in Lake Michigan at a concen- tration of 0.000006 ppm is biomagnified in lake trout to levels of 10-28 ppm (U.S. EPA 19725), and in herring gulls to 99 ppm (Hickey et al. 1966). The lake trout residues averaged 53 per- cent DDE, 15 percent DDD, and 32 percent DDT (U.S. EPA 1972/;). DDT applied to a marsh in New Jersey for mosquito control was found in fish at 0.17-2.07 ppm and in gulls at 75 ppm (Woodwell et al. 1967). DDD, or 2,2-bis-(p-chlorophenyl)- 1,1 dichloroethane, exhibited similar model-ecosystem behavior to that of 396 Illinois Natural History Survey Bulletin Vol. 31, Art. 9 DDT (Table 35) and is, in fact, a degradati\'e product of DDT (Table 33). DDD constituted 58.9 percent of the total extractable radioactive ma- terials in the snail, 59.0 percent in the mosquito, and 85.4 percent in the fish (Metcalf et al. 1971). Thus, although DDD is a step on the degradative pathway of DDT and does not form the environmentally recalcitrant DDE, DDD seems to offer only slight im- provement over DDT in regard to en- vironmental hazard. Its ultimate fate in higher animals is conversion to and excretion as DDA (4,4'-dichlordiphenyl acetic acid), but this is an extremely slow process. DDD applied to Clear Lake, California, to control the Clear Lake gnat, Chaobonis astictopus, was found to be bioconcentrated through food chains from 0.02 ppm in the water to 903 ppm in the fat of plankton-eating fish and to 2,690 ppm in the fat of carnivorous fish (Hunt & Bischoff 1960). Methoxychlor, or 2,2-bis-(p-methoxy- phenyl ) - 1, 1, 1 -trichloroethane, differs from DDT in two important ways. It is 500 times more soluble in water, and the aryl CH.5O groups ( degradophores ) are readily biodegradable to OH groups, further increasing the polarity and water solubility. Thus, as shown in Table 36, methoxychlor is much less accumulative than DDT is in most ani- mals. Methoxychlor amounted to 84.0 percent of the total extractable radio- active materials in the snail and 51.5 percent in the fish. In contrast to the ready conversion of DDT to DDE ( Table 33 ) and the storage of the latter in animal tissues, only very small amounts of the corresponding methoxy- chlor ethylene are stored by animals. The principal degradation pathway for methoxychlor is through conversion to the mono-OH and di-OH derivatives, which are readily converted to polar conjugation products in animals (Met- calf et al. 1971). Methoxychlor is classed as a mod- erately persistent insecticide and does not accumulate to high levels in most animal tissues or milk. It offers a severe toxic hazard to fish but is degraded in fish much more readily than is DDT (Reinbold et al. 1971). When used for control of the elm bark beetle, Scohjtus multistriatus, vector of Dutch elm disease, methoxy- chlor has not resulted in environmental problems of transfer from earthworms to birds, as has DDT (Hunt & Sacho 1969). Aldrin, or 1,2,3,4, 10, 10-hexachloro- l,4,4a,5,8,8a-hexahydro-l,4-endo, exo-5, 8-dimethanonaphthalene, is rapidly con- verted in the model ecosystem and its organisms to the very persistent 6,7- epoxide, dieldrin (Table 37). In the model ecosystem treated with aldrin, dieldrin was stored as 85.7 percent of the total extractable radioactive ma- terials in the alga, 91.6 percent in the snail, and 95.8 percent in the fish ( Met- calf et al. 1973). The bioaccumulation of both aldrin and dieldrin is high, directly proportional to their water in- solubility, but not as high as that of DDT and DDE. Only minor amounts of two degradation products, 9-keto dieldrin and 9-hydroxy dieldrin, were found, attesting to the stability of dieldrin, and these two products were also concentrated in the alga, snail, and fish. The ultimate degradative path- way is through frans-dihydroxydihydro aldrin. Aldrin, because of its rapid con- version to the highly persistent dieldrin, its bioaccumulation, and its carcino- genicity ( Walker et al. 1973 ) , has been banned as an insecticide by the U.S. Environmental Protection Agency. Dieldrin. When the model-ecosystem evaluation of dieldrin, the 6,7-epoxide of aldrin, was begun (Table 38), little difference was found between it and the evaluation of aldrin (Table 37). Dieldrin is slightly more water soluble than aldrin and exhibited slightly lower bioconcentrations in the fish. The sta- bility of dieldrin was shown by the storage of dieldrin as 98.7 percent of the extractable radioactive materials in Aug., 1975 Metcalf & Sanborn: Pesticides and Environmental Quality 397 the alga, 99.0 percent in the snail, and 97.8 percent in the fish (Sanborn & Yu 1973). However, 9-OH and 9-C=0 dieldrin were identified as important degradation products along with trans- dihydroxydihydro aldrin. The se\'eral thousandfold accumula- tion of dieldrin in the fish of the model ecosystem following the application of aldrin is in agreement with observa- tions in nature. Humans in the USA have average values of 0.29-0.31 ppm of dieldrin in fatty tissues (Durham 1969). Dieldrin in Lake Michigan at a concentration of 0.000002 ppm in water is biomagnified in lake trout to levels of 0.14-0.45 ppm (U.S. EPA 1972fo). The average bioconcentration of dieldrin from the waters of Illinois farm ponds to the tissues of fish was 5,000- to 20,000-fold (W. F. Childers & W. N. Bruce, Illinois Natural History Survey, unpublished data). To.xaphene has been sho\vn to be a mixture of at least 177 components (Holmstead et al. 1974) about two- thirds of which are C,„H,,Cb, C,„H,„ Cl^, and C,„H,,C1,, compounds. The highly insecticidal components are hep- tachlorobornanes (Casida et al. 1974). The '''C-radiolabeled toxaphene used in the model-ecosystem experiments was supplied by the manufacturer as the chlorination product of -|8-"Cj> cam- phene to 67-69 percent CI (sample X19093-4-2K ) and is presumably repre- sentative of the technical product. As shov\'n in Table 39, the '"C-radiolabeled toxaphene behaved in a surprisingly homogenous fashion in the extracts from the organisms of the model eco- system. The major ingredients referred to as "toxaphene" (Rt 0.70) were highly persistent and accumulated to several thousandfold levels in the organisms of the system. "Toxaphene" constituted 82.6 percent of the total extractable radioactive materials in the alga, 86.6 percent in the snail, 62.7 percent in the mosquito, and 64.9 percent in the fish. The uncxtractable "C-labeled materials averaged 19 percent of the total radio- active materials in all of the organisms. Thus, toxaphene exhibited model-eco- system behavior rather like that of endrin (Table 40). The behavior of toxaphene in the en- x'ironment is little known because its enonnous number of constituents poses almost insurmountable analytical prob- lems. Toxaphene in Big Bear Lake, California, at 0.2 ppm was found to be biomagnified to 200 ppm in goldfish (Hunt & Keith 1963), and in Lake Poinsett, South Dakota, from 0.001 ppm in the water to 0.176 ppm in the tissue and 1.1.52 ppm in the fat of the carp, Ct/piimis carpio (Hannon et al. 1970). These instances of thousandfold bio- magnification are in perfect agreement with the model ecosystem results. Endrin is a highly water-insoluble pesticide that was also bioconcentrated in the organisms of the model ecosys- tem to a high degree (Table 40). Endrin, or 1.2,3,4,10,10-hexachloro-6,7- epoxy- l,4,4a,5,6,7,8,8a-o c t a h y d r o - 1 , 4- e»ir/o,e/irfo-5,8-dimethanonaphthalene, is the enf/o,en(/o-isomer of dieldrin and is less environmentally persistent than dieldrin. Endrin was stored as 84.9 percent of the total extractable re- labeled materials in the alga, 83.0 per- cent in the snail, and 75.9 percent in the fish. Degradation appeared to be largely through an unknown compound designated II, probably 9-OH endrin in analogy with dieldrin. Unknown compound III is probably 9-C=0 endrin (Metcalf et al. 1973). Biological observations on the orga- nisms of the system were particularly :nformati\'e. Endrin was not only highly toxic to the salt-marsh caterpillar, which had difficulty consuming the treated sorghum leaves, but repeatedly killed all the daphnia, mosquito larvae, and fish in the aquatic portion of the sys- tem. The high toxicity of the water phase persisted for more than 60 days from the beginning of the experiment and occurred at endrin concenti'ations of 0,001-0.002 ppm. Because of this toxicity the experiment was extended 398 Illinois Natural History Survey Bulletin Vol. 31, Art. 9 lo nearly twice the usual 33-day period, and thus the data in Table 40 were measured after 63 days. Fish added to the model system had violent convul- sions within 10-15 minutes after being placed in the contaminated water. These biological observations demon- strated the substantial predictive value of the model-ecosystem investigations and could have given a preview of the Mississippi River fish kills associated with the leaching of endrin wastes (Barthel et al. 1969). Endrin, because of its great bioaccumulation, persist- ence, and extremely high toxicity to a wide variety of organisms, is a highly dangerous insecticide. Lindane, or gamma-l,2,3,4,5,6-hexa- chlorocyclohexane, has a higher water solubility than many of the other or- ganochlorine insecticides and appears to be less readily bioconcentrated in animal tissues (Table 41). In the model ecosystem lindane was stored as 20.6 percent of the total extractable radio- active materials in the snail and 91.7 percent in the fish. None could be detected in the alga or the mosquito. The principal degradation product ap- peared to be gamma-pentachlorocyclo- hexene. Lindane is substantially more biodegradable than DDT and the cyclo- diene pesticides, and it appears to be degraded environmentally to a series of trichlorophenols (Metcalf et al. 1973). BHC residues have been found widely distributed in human fatty tissues in the USA at 0.20-0.60 ppm (Durham 1969). The beta-isomer (an ingredient of technical BHC insecticide) is the most persistent isomer of lindane, and the environmental persistence of the gam;7ia-isomer (lindane) is not well understood. Mirex, dodecachloro-octahydro-1,3,4- metheno-2H -cyclabuta- {c,d]»-pentalene, was one of the least degradable com- pounds that we evaluated and was stored as 97.8 percent of the total ex- tractable radioactive materials in the alga, 99.4 percent in the snail, 99.6 per- cent in the mosquito, and 98.6 percent in the fish (Table 42) (Metcalf et al. 1973). It is clearly a highly persistent pollutant and showed a substantial de- gree of bioaccumulation. Mirex is of environmental importance, as it is one of the most effective inducers of mi- crosomal oxidase enzymes. Mirex, fol- lowing its widespread use as a bait for the fire ant, has been found in tissues of wild birds at levels of up to 3 ppm and in rodents at nearly 20 ppm ( Un- published data ) . It has also been found in tissues of northern pike and long- nose gar from Lake Ontario at 0.020- 0.050 ppm (Kaiser 1974). Heptachlor, or l-exo-4,5,6,7,8,8-hep- tachloro-3a,4,7,7a,-tetrahydro - 4,7-meth- rnoindene, has a low level of water solubility and a high potentiality for bioaccumulation (Table 43). Hep- tachlor is rapidly converted in the model ecosystem and its organisms to the very persistent 2,3-epoxide, hep- tachlor epoxide. In the model eco- system heptachlor epoxide was stored as 59.1 percent of the total extractable radioactive materials in the alga, 45.6 percent in the snail, and 60.6 percent in the fish. These values are consider- ably lower than the corresponding values for the storage of dieldrin after the treatment of crops with aldrin (Table 37) and reflect the existence of an alternate degradative pathway in heptachlor, the replacement of the 1-Cl atom by OH to give 1-hydroxy- chlordene. This degradative product is more polar and water soluble than heptachlor and is not as highly ac- cumulative. It can also be epoxidized in vivo to the 2,3-epoxide, 1-hydroxy- chlordene epoxide, which was found stored in the snail, mosquito, and fish. This latter degradative product could also be formed by hydrolysis of hepta- chlor epoxide. Heptachlor epoxide in the model ecosystem (Table 44) showed a persistence comparable to that of dieldrin (Table 38). In the heptachlor test the unextrac- table '*C-labeled materials averaged 29 percent of the total radioactive ma- terials in the various organisms. Hepta- Aug., 1975 Metcalf & Sanborn: Pesticides and Environmental Quality 399 chlor epoxide is widely distributed in the environment, and the average level in the bodv fat of humans in the USA is 0.1-0.24 'ppin (Durham 1969). Yel- low perch from Lake Michigan had heptachlor epoxide body residues rang- ing from 0.060 to 0.097 ppm (U.S. EPA 19725). Heptachlor and heptachlor epoxide are under surveillance by the U.S. EPA because of their carcinogen- icity (Carter 1974). Chlordane, or 1,2,4,5,6, 7,8, 8-octa- chloro - 3a, 4, 7, 7a-tetrahydro-4, 7 - metha- noindane, is chemically related to hep- tachlor except that the double bond has been chlorinated. The behavior of this insecticide in the model ecosystem clearly demonstrates its persistence and tendency to accumulate in the orga- nisms of this system (Table 45). The water of the model ecosystem contained only 5.98 percent chlordane, but the alga, snail, mosquito, and fish contained 94.51, 91.17, 47.64, and 77.86 percent, respectively, of their radioactive ma- terials as chlordane. The EM values for chlordane for the alga, snail, mos- quito, and fish were 98,386, 132,613, 6,132, and 8,261, respectively. Clearly, the continued use of chlordane, along with its minor contaminant, heptachlor, will lead to problems of accumulation in food chains, which can lead to resi- dues of these two pesticides in humans. Unpublished data accumulated by fed- eral monitoring agencies ha\e indicated that 95 percent of the adipose tissue taken from humans in the United States contains residues of heptachlor. Fur- ther, nearly 70 percent of U.S. poultry, fish, and dairy products contain resi- dues of heptachlor. The data of this model-ecosystem experiment provide background information which explains the high incidence of heptachlor resi- dues in humans and food. FUNGICIDE TEST RESULTS Captan, or N-trichloromethylthio-4- cyclohexene-l,2-dicarboximide, is the most versatile of the general foliar fungicides for the treatment of fruits and vegetables. In the model eco- system it was found to be extensively degraded, producing at least 15 degra- dation products in the water phase (Table 46). No intact captan was identified in any of the organisms of the system, and only trace amounts of degradation products were found. Cap- tan appears not to offer any environ- mental problems following normal use. Hexachlorobenzene has had some use as a fungicide in seed treatment, replacing in part the organomercurial fungicides. In the model system it was extremely persistent and substantially bioaccumulative, the parent compound comprising 85.1 percent of the total extractable radioactive materials in the alga, 87.2 percent in the daphnia, 58.3 percent in the mosquito, and 27.7 per- cent in the fish (Table 47) (Metcalf et al. 1973). EM values ranged from 144 to 1,248. The degradation of hexa- chlorobenzene occurs through hydroly- sis to pentachlorophenol and other chlorophenols of increasing water solu- bility. Hexachlorobenzene used as a fun- gicide on wheat caused an epidemic of thousands of cases of cutaneous porphyrinuria in humans in Turkey ( Schmid 1960 ) , and the compound has been found in human tissues nearly everywhere, ranging up to 0.29 ppm in adipose tissues in Great Britain (Abbott et al. 1972). Hexachloroben- zene is clearly an undesirable environ- mental pollutant. Pentachlorophenol is the fungicide in largest scale use in the United States as a timber and paper pulp preservative and mildewproofer. It is also used as a soil and timber poison against ter- mites and as a nonselective herbicide. In the model ecosystem pentachloro- phenol accumulated in the various or- ganisms to a moderate degree (Table 48). EM values were 5-205. Penta- chlorophenol constituted 15.1 percent of the total extractable radioactive ma- terials in the alga, 12.2 percent in the snail, 33.3 percent in the mosquito. 400 Illinois Natural History Survey Bulletin Vol. 31, Art. 9 55.5 percent in daphnia, and 51.2 per- cent in the fish. It is apparently de- graded through a series of chlorinated jphenols, and 10 degradation products were found in the water phase. Pentachlorophenol, because of its high toxicity to nearly all forms of life as an oxidative phosphorylation un- coupler and its stabiUty, can be a dangerous environmental pollutant. Its use as an herbicide in Japan has re- sulted in its presence in almost all Japanese river waters at concentrations of 0.01-0.1 ppb (Goto 1971). DISCUSSION The data shown in the preceding tables, illustrating the fates of a variety of pesticides in the laboratory model ecosystem, can be used for predictive purposes in a number of ways. BIOLOGICAL EFFECTS The dosages applied in the model ecosystem are realistic in terms of those used in the field, i.e., 0.2-1.0 pound per acre (0.22-1.1 kg per ha). There- fore, the biological results observed are meaningful as predictors of the en- vironmental impact of the pesticide studied. The most dramatic results on nontarget species were found with the organochlorine insecticides endrin, diel- drin, and heptachlor epoxide. Endrin apphed at tlie equivalent of 0.2 pound per acre (0.22 kg per ha) repeatedly killed all daphnia and mosquitoes in the system, and the necessity for re- stocking delayed the termination of the experiment to over 60 days. Fish added to the endrin system showed violent convulsions within 10-15 minutes and died within a few hours. Similar re- sults were experienced with heptachlor epoxide, which killed daphnia and mos- quitoes for 56 days after having been applied at 0.2 pound per acre (0.22 kg per ha). Dieldrin was highly toxic to daphnia and mosquitoes, which did not survive at any time during the ex- periment. Temephos, the highly effective mos- quito larvicide, killed mosquito larvae so persistently that the experiment was prolonged to 53 days. Chlorpyrifos and methyl chlorpyrifos even at the 1.0-mg dosage were highly toxic to daphnia, and chlorpyrifos adversely affected algae. The carbamate insecticides carbaryl and carbofuran were extremely toxic to daphnia in the initial stages of the experiments. Some of the herbicides, especially metrabuzin and bifenox, were highly toxic to algae in the model ecosystem. Surprisingly, the insecticide methoxy- chlor, or its degradation products, also affected algae adversely. DEGRADATIVE PRODUCTS This parameter is, of course, the di- rect measure of biodegradability. In general, the larger the number of degradative products in the water and in the organisms of the model eco- system, the lower the degree of eco- logical magnification and the higher the amount of unextractable radioac- tive materials. Thus, DDE with two degradation products and DDT with four were the worst offenders in eco- logical magnification in contrast to temephos, carbaryl, and metrabuzin, each with 11 degradative products, and chlordimeform with 13; each of the latter four compounds showed zero ecological magnification. Clearly, the relationship is not precise, because the variety of positions of radiolabeling limits the extent to which degradative products can be identified. Moreover, the formation of secondary toxicants, such as the epoxides, e.g., dieldrin from aldrin and heptachlor epoxide from heptachlor, provides products that are substantially more environmentally stable and ecologically magnified than are the parent compounds. Nevertheless, knowledge of the key degradative products of any pesticide is important in characterizing its en- vironmental impact. The model eco- system not only provides useful in- formation about the chemical nature of degradation products and about Aug., 1975 METCALF& Sanborn: Pesticides AND Environmental Quality 401 degradative pathways, but also indi- cates potential rates and locations of storage and bioconcentration of pesti- cides and their degradation products. As examples, in addition to those of dieldrin and heptachlor epoxide, Bana- mite (Table 49) produced an unidenti- fied degradation product, designated II, which was ecologically magnified .3,013-fold in fish and 19,824-fold in snails. Metrabuzin (Table 12) pro- duced an unidentified product, desig- nated II, which was ecologically mag- nified 175-fold in fish. Even the highly degradable malathion produced an unidentified product, designated III, which showed apparent ecological mag- nification of about 19,500-fold (Table 20). ECOLOGICAL MAGNIFICATION The accumulation of lipid-soluble, water-insoluble pesticides in living or- ganisms is one of the most disturbing features of environmental pollution by loV 106- 5 I05. O '®- 50 ppm, likely to be environmentally nonhazard- ous 3. water solubility from 0.5 to 50 ppm, to be used with caution The lines of demarcation between the three classes obviously are not sharp, and the ultimate hazard also depends upon lipid partitioning, the rapidity of pesticide degradation in living ani- mals, use patterns, and amounts ap- plied. However, practical experience has already shown that most of the pesticides with water solubilities of <0.5 ppm demonstrate bioaccumula- tion following field use and that most of those with water solubilities of >50 ppm have not shown bioaccumulation. The large group of pesticides with water solubilities between 0.5 and 50 ppm represent those which may demon- strate bioaccumulation under some con- ditions of use, e.g., in lakes or oceans with very cold water. Their use pat- terns should be judged accordingly. UNEXTRACTABLE RADIOACTIVE MATERIALS This parameter measures the conver- sion of the pesticide under investigation and its primary degradation products into simple degradation products which enter the metabolic pool of an orga- nism and are resynthesized into normal tissue ingredients. The percentage of unextractable radioactive materials can be determined for many of the pesticides investigated by adding the amount of T. o io3_ 102- o 10 O ® o o o o 10 "^s ^0 — -^—i^ 09 "eb 7*5 go id lio PERCENTAGE OF UNEXTRACTABLE '"^C IN FISH Fig. 3.—The relationship between the percentage of radioactive materials extractable from the mosquito fish of the laboratory model ecosystem and the total body accumulation of parent pesticide, numbered as in Tables 2-49, and all of its degradation products. There is a highly significant correlation (r = —0.74) . Aug., 1975 Metcalf & Sanborn: Pesticides and Environmental Quality 403 unextractable radioactive materials to the total extractable radioactive mate- rials and determining the fraction. The \'alues obtained in the fish (Gambiisia), for example, range from 0.34 percent for DDE to about 90 percent for feni- trothion. As shown in Fig. 3, a highly significant correlation ( r = —0.74 ) ex- ists between the percentage of unex- tractable radioactive materials and the in vivo stability of the pesticide and its principal degradation products as mea- sured by the total biomagnification of the radioactive materials from the water to the fish (or other organism). Considering that two different methods for determining amounts of un- extractable radioactive materials were used, i.e., total combustion analysis and solubilization, the results are sur- prisingly predictable. Clearly, pesti- cides and their degradation products which are highly lipid soluble in the tissues of organisms are almost quantitatively extractable and leave small amounts of unextractable radio- active materials. As a tentative guide- line we suggest that pesticides which produce 40 percent or more of unex- tractable radioactive materials in the fish in the model ecosystem evaluation will not be likely to cause serious prob- lems with environmental quality. 404 Illinois Natural History Survey Bulletin Vol. 31, Art. 9 Aug., 1975 Metcalf & Sanborn: Pesticides and Environmental Qu.\lity 405 o o o o o o o o o o o iH CO t- CC *bC S i' g i & iS '3 ~ A m >> " 5 ° '2 £ S >> '5 S o.^ o I §• S 6 c II § m « B o t- o o O O M- t- «o lO o CO o o . I Eh Q- 4 iw E S Aug., 1975 Metcalf & Sanborn: Pesticides and Environmental Quality 411 Table 1 1.—Rf values and amounts, in parts per million, of trifluralin" and its degradation products found in the water and organisms of a model ecosystem. Daphnid Physa Water (water flea) (snail) Culex Gambusia (mosquito) (fish) Total »C 412 Illinois Natural History Survey Bulletin Vol. 31, Art. 9 Table 13.—Rt values and amounts, in parts per million, of bifenox' and its degradation products found In the water and organisms of a model ecosystem. Oedogonium Physa Culex Gambusia Ri" Water (alga) (snail) (mosquito) (fish) Total "C Aug., 1975 Metcalf & Sanbobn: Pesticides and Environmental Quality 413 Table 16.—Rt values and amounts, in parts per million, of Counter®" and its degradation products found in the water and organisms of a model ecosystem. 414 Illinois Natural History Survey Bulletin Vol. 31, Art. 9 Table 18.—Rt values and amounts. In parts per million, of fonofos' and its degradation products found in the water and organisms of a model ecosystem. Aug., 1975 Metcalf & Sanborn: Pesticides and Environmental Quality 415 Table 20.—Rt values and amounts, in parts per million, of malathion" and its degradation products found in the water and organisms of a model ecosystem. 416 Illinois Natural History Survey Bulletin Vol. 31, Art. 9 3 E nj a; ss. s Aug., 1975 Metcalf & Sanborn; Pesticides and Ennironmental Quality 417 Table 22.—Rr values and amounts, in parts per million, of leptophos" and its degradation products found in the water and organisms of a model ecosystem. 418 Illinois Natural History Survey Bulletin Vol. 31, Art. 9 - p o o o CO Oi oo oO iH CO iHM r-J ff C^o o o o o o oo o o o o o o o o o o o o o o o o fe: w 3 C § "^^ ^ o o o o =, 'u a s n p. 0.6 S 5 ° 2 * ."So o >" 2 o 2 e N « 3 r g C >< J2 O c« b ,C! -^ rS 0) S. , 3 g S 5 ^ "7 i £ M ci .S 5 p i ? g ? " !25 ? ; " !>. >i o >. 5? 11 i S I g I ! >> o S a "0 'O . .« .M ci c- ci ci SK>>>SoD 432 Illinois Natural History Sur\^y Bulletin Vol. 31, Art. 9 tH O M "^ O O • rH o o o OO tM 0> O O 1-1 o oo o o o o o T-5 o o i-i o o