Document QXZ8q1O3N87dM2nKKVjkxOqrL

carbon tetrachloride1,495(1969). in brains and bodies of (1966). dmium, and lead. Ann. ebilization of DDT by riobcnzcnc in Japanese production, and tissue md gross development M). 20,1974 LABORATORY MODEL ECOSYSTEM STUDIES OF THE DEGRADATION AND FATE OF RADIOLABELED TRI-, TETRA-, AND PENTACHLOROB1PHENYL COMPARED WITH DDE ROBERT L. METCALF. JAMF.S R. SANBORN, PO-YtJNC UJ and DONALD NYE Department of Entomology and Environmental Studies Institute. University of Illinois and Illinois Natural History Survey. Urhana-Champatgn Urbcna, Illinois 6 / SOI Radiolabeled tri-, letra-, and pentachlorobiphenyls (PCB) and DDE were studied in a laboratory model ecosystem for degradation pathways, and biomagmfivaiion in alga, snail, mosquito, and fish. Trichlorobiphenyl was degraded in ail the organ isms of the model ecosystem much more rapidly than tetrachloro- and peruachlorobiphenyl. Pentachlorobiphenyl was approximately as persistent as DDE There was a linear relationship between lipid/water partition and ecological magni fication and between water solubility and ecological magnification. No evidence of conversion of DDE to PCB was detected. The laboratory model ecosystem previously described (Metcalf et al. 1971) has been employed for the estimation of the environmental fate of DDT and a number of its analogues (Kapoor et al. 1970, 1972, 1973) and for study of aldrin, dicldrtn, endnn. mirex, lindane, and hexachlorobenzene (Metcalf et al. 1973a). The methodology de veloped has yielded useful information about (1) the degradation pathways of the various xenobiotics, (2) the toxic effects of the compounds and their degradation products, (3) their comparative biomagniiication and food chain concentration, and (4) their comparative biodegradability; ail in organisms of five phyla linked in sevcial food chains. This information has proved of value in characterizing the potential environ mental pollutant effects of candidate insecticides (Kapoor et al. 1973, Coats et at. 1973) and of plasticizers (Metcalf et al. 1973b). In this paper we report the application of these techniques to a better understanding of the comparative environmental properties of trichloro-, tetrachloro-. and pentachlorobiphenyl (PCB's), and of dichlorodiphenyldichloroethylene (DDE) the persistent DDT degradation product. Methods and materials The laboratory model ecosystem evaluation was carried out in a small glass aquarium with a sloping terrestrial-aquatic interface of pure white sand exactly as previously de scribed (Metcalf et al. 197t). The l4C radio-labeled compounds were applied quantita tively from acetone solution at 5.0 mg (or ca. one kg per ha) to Sorghum vulgarc seedlings grown in the terrestrial portion. The treated leaves were consumed by fourth instar salt Archive* of Environment*! Contammalwn and Toxkolofy. Vol J. No 2. 1975 C 1975 try Sponger-Verta# New York Inc. V 151 0&5alb 152 R. L. Metcalf et al. marsh caterpillar larvae Estigmene acrea, whose activities and fecal products contaminated the aquatic portion of (he system. The radiolabeled products were transferred through several food chains, e.g., alga (Ovdogonium cardiacum) -* snail (Physa)i plankton -+ water flea (Daphrua magna) -* mosquito (Culex pipiens qmnquefasciatus) -* fish {Gambusia affims). After 33 days in an environmental chamber at 26(>C and a 12-hr photoperiod at 5,000 foot candles simulated daylight, (he organisms were extracted with acetonitrile and the 14C-radiolabelcd com pounds evaluated by TLC on silica gel containing fluorescent marker (E. Merck GF-254) and radioautography on no-screen x-ray film. Liquid scintillation counting of the individual components was done in cocktail D (5 g PPO and 100 g naphthalene in dioxanc to make one liter) and counts were corrected to dpm by using channels ratio quenching correction. The residues, after extraction, were counted by total combustion to ,4C0j by the Schoniger oxygen flask technique (Kelly et al. 1961) to determine the uncxtractablc radioactivity. Whenever possible, the identity of individual components on the TLC plates was determined by cochromatography with known standards and by extraction and mass spectrometry. Radiolabeled compounds. The individual >4C-labeled PCB's were obtained from Mallinkrodt.St. Louis, Missouri. They were: 2,5,2'-trichlorobiphenyl (2,5-dichlorophenylring-UL-14C), 9.91 mCi per mmole with > 98% radiopurity and 41.5% Cl, and a principal constituent of Atoclor 1242 (Webb and McCall 1972); 2,5,2\5'.ietrachlorobiphcny! (ring-UL-14C), 9.87 mCi per mmole with > 98% radiopurity and 48.7% Cl, and a principal constituent of Aroclor 1248 (Webb and McCall 1972); and 2,4,5,2',S-pcntachlorobiphenyl ^'.S'-dichlorophenyl-ring-UU1 'C), 9.87 mCi per mmole with > 98% radio purity and 54.4% Cl, a principal constituent of Arocloi 1254 (Webb and McCall 1972). ,4C labeled 2,2-bu-(p<hlorophenyl)-l,l-dichloroethylene (DDE) was prepared from *4C-ring-UL p.p' DDT obtained from the Radiochemical Centre, Amersham, England, 5.48 mCi per mmole, by dehydrochlorinating with 1.0 M alcoholic KOU, and purifying on a silicic acid column with hexane elution to 99% radiopurity. Results PCB't. The movement of >4C radioactivity from Sorghum plants into the water phase of the model ecosystem is shown in Figure 1. All three chlorinated biphenyls reached a maximum concentration in water at about seven days after treatment and the levels of contamination declined as the PCB's were taken up by the organisms of the system. The levels of the chlorinated biphenyls in the water phase (Table I) were in the ppb range, below the water solubility of the compounds as determined by radiotracer technique (Table 11). Radioautographs of the extracts from the components of the model system after TLC are shown in Figure 2. The data in Table 1 represent the quantitative distribution of the 14C in the spots on the TLC plates. The results for the three PCB's are also expressed in HONS 085817 roducls contaminated bod chains, e.g., alga a (Oaphnia magna) -* 0- After 33 days in an fool candles simulated *C-(adio)ibelcd comker (E. Merck CF-254) lion counttug of the taphfhaicnc in dioxanc lanntls ratio quenching combustion to l4C03 lermine the uncxtract* d component* on the wn standards and by ; were obtained from yl (2,5-dichlorophenyl1.5% Cl, and a principal '.S'-ttltachlorobiphcnyl 8.7% Cl, and a principal 4.5.2\5'pcniach)orubi4e with > 98% radio ebb and McCall 1972). )E) was prepared from e, Amersham, England, lie KOH, and purifying Degradation of Polychlorinated Biphenyls Compared with DDl: 153 Tible II in terms of ecological magnification (E M.) (ppm in organism/ppm in water) and of biodegradabilily index (B.l.) (ppm polar degradation products/ppm nonpolar products). The E.M. values for the parent compounds increased substantially with the number of chlorine atoms, from tricMurobiphenyl (41.5% Cl) to tetrachlorobtphcnyl (48.7% Cl) to pentachiorobiphenyl (54.4% Cl). Conversely the B.l. values decreased with increasing degree of chlorine. This consistent and regular behavior gives added confidence that these parameters are ecologically significant (see Kapoor ct al. 1973) and must be a function of the number of C-H bonds available for hydroxylation by microsomal oxida tions in the various organisms. The spots of low Rf value (0.02-0.06), Figure 2, are presumably hydroxylated PCB compounds and (he polar radioactivity (Rr 0.0) is thought to consist of conjugates of these compounds. Wallnoter era/. (1973) have found 4-chloro4'-hydroxybiphcnyl as a metabolite of 4-chlorobiphenyl from soil fungus. Rhizopus japonicus. Yoshimura and Yammamoto (1973) have reported the 5-hydroxylatcd deriva tive as the major and the 3-hydroxylatcd derivative as the minor excretion product of 2,4,3',4'-tetr3chlorobiphcnyI in the rat. Hutzinger et at. (1972) have shown that rat and pigeon could hyc.oxylate 2,5,2\5'-tetrachlorobiphcny! but they could not detect hydroxylated metabolites in brook trout. However, the amounts of polar material in Gambusia (Figure 2, Table I) suggest that this fish is able to slowiy hydroxylatc this tetischlorobipheny 1. nts into the water phase ltd biphenyl* reached a Kmcnt *d the level! of Huns of Ihe system. The I svete In the ppb range, .y ladlotiscer tedtnique model system efter TLC utive distribution of the 'B's lie also expressed in Fig. I. Movement of total ,4C radioactivity from plants into the water phase of the model ecosystem and uptake by organisms. MGNS 085818 X I L. S- Table I. Distribution of chlorinated biphenyls and their degradation products in the model ecosystem H30 Chlorinated biphenyl equivalents (ppm) Oedogonium (alga) Physa (snail) Cutex Cambusta (mosquito) (fish) 1. l.S.l'-trichlorobiphenyl total ,4C Unknown I (Rf 0.66) trichlorobiphenyl (Rf 0.56) Unknown 11 (Rf 0.23) Unknown 111 (Rf 0.10) Unknown IV (Rf 0.06) Unknown V (Rf 0.04) Unknown VI (Rf 0.03) Polar (Rf 0.0) Unextractable 0.03845 0.00015 0.00020 0.00005 _ 0.00055 0.00040 0.00040 0.02265 0.01405 23.2155 15.9575 1.4630 0.0520 _ __ _ 0.0685 0.5185 5.1560 31.2015 18.9720 1.1590 0.6480 0.9735 0.5460 0.2205 0.4410 3.9315 4.3100 2.7030 1.1995 0.1630 + _ _ _ 0.4795 0.8610 3.2055 0.2085 1.2800 0.1595 _ _ _ _ 0.9985 0.5590 II. 2,5,2',5'-tctrachloro biphenyl totalf 4C tetrachlorobiphenyl (Rf 0 48) Unknown 1 (Rf 0.23) Unknown 11 (Rr 0.04) Polar (Rf 0.0) Unextractable 0.02065 0.00120 0.00005 0.00155 0.01225 0.00560 23.6845 21.5975 0.3220 0.1030 0.3275 1.3345 53.7465 47.3275 0.7560 0.4360 3.9850 1.2420 14.5335 12.6745 0.1070 0.9670 0.7850 15.5685 14.2360 0.0890 0.8545 0.3900 lll.2,5,2',4',5,-penta. chtorobiphcnyl total *4C pentachlorobtphenyl (Rf 0.55*) Unknown 1 (Rf 0.46) Unknown 11 (Rf 0.39) Unknown 111 (Rf 0.21) Unknown IV (Rf 0.04) Unknown V (Rf 0.02) Polar (Rf 0.0) Unextractable 0.04340 0.00985 _ 0.00020 0.00015 0.00030 0.003 85 0.02055 0.00850 62.4660 53.8440 0.6850 0.5080 0.1425 _ 0.2570 1.6265 5.4330 TLC with hexane (Skellysolve B.bp 60-68C). 633.0165 181.4565 127.6945 587.3545 170.8480 6.6210 2.4070 2.2490 1.3195 1.9365 1.0520 0.5000 7.4965 16.5550 8.3040 2.6745 3.1555 1 19.7060 2.5380 0.5810 0.3285 _ 0.7450 2.36)0 1.4350 154 MGN5 G0^dl9 Table II. Ecological magnification (EM.) and Biodegradability index (8.1.) of ECB's and DDE compared with water solubility and partition coefficient Chemical HjO solubility (ppb) Partition coefficient Ecological magnification (E.M.) Alga Snail Mosquito Fish Biodegradabiiity index (B.I.) Alga Snail Mosquito Fish tri-Cl-PCB 16 7,803 7,315 5,795 815 6,400 0.30 0.17 0.35 0.60 tetra-Cl-PCB 16 8,126 17,997 39,439 10,562 11,863 0.015 0.082 0.076 0.060 penta-Cl-PCB 19 16,037 5,464 59,629 17,345 12,152 0.029 . 0.027 0.0134 0.019 DDE 1.3 18,893 11,251 36,342 59,390 12,037 0.069 0.049 0.033 0.050 MONS 0 8 5 8 8 0 I mi 4 i. N 156 R. L. Metcalf ct at The pcntachlorobiphcnyl with B.I. values of 0.019 to 0.027 in fish and snail is very comparable in model ecosystem behavior to DDT, B.I. 0.015 and 0.044 (Kapoor ct at. 1973) and this suggests lhat the two compounds should behave similarly in the environ ment (Riscbrough ct al. 1968). Properties of the tctrachlorobiphcnyl were similar to those of the pcntachlorobiphenyl (Figure 2) bvit the trichlorobiphcnyl was much more degradable. A prominent degradanve product (Rf 0.66) is stored in alga, snail, and mosquito larva in much greater quantities than the parent compound. This compound is less polar (higher Rf) in the hexane solvent than any of the three PCB isomers. As shown in Table I it is magnified to very high values, 106.382X in alga and 126.480X in snail, is stored in lipids, and is highly persistent. Its presence in high amounts m alga and in the snail and mosquito which are alga feeders suggests that it might be formed by phomchemical processes during photosynthesis in the alga. This compound forms slowly and no traces of it were visible in three-day uptake studies of trichlorobiphcnyl by alga, snail, daphnia, mosquito or fish (Metcalf and Lu 1973) although it appeared in alga in . i , | t , t Ct Cl Cl Cl * Cl Cl Cl 0 V.- , Q ti, Fig. 2A. Radioautogram of TLC plate containing extracts of water and organisms treated with 2,5,2-trichlorobiphenyl. A (*>. F (fish), M (mosquito larva), S (snail) and STD (,4C-radiolabeicd compound) Fig. 2B. Radioautogram of TLC plate conlaining extracts of water and organisms treated with 2,5,2',S'-(etrachlorobiphcnyl. A (alga), F (fish), M (mosquito larva), S (snail) and STD (l4C-radiolabeled compound). 0858il Fii* Uu Ira phe lac laH fish and (naif is very 0.044 (Kapoor cl at. nilaily in (he environ>rnyl were similar to lenyl was much more d in alga, snail, and >nd- This compound is CB isomers. As shown d 126.480X in snail, is mis in alga and in (he be formed by photo Mind foims slowly and dorobipltenyl hy alga, i it appeared in alga in Degradation of Polychlorinated Biphenyls Compared with DDL 157 14-day studies. To data we have been unsuccessful in identifying (he unknown by mass spectrometry. DDE. This compound has been implicated as a possible environmental precursor of PCB isomers (luough photoxidation reactions involving radical rearrangements to 3,6-dichlorofluorcnone intermediates (Plimmer et at. 1970, Pcakall and Lmcer 1970, Moilanen and Crosby 1973). Although such rearrangements could logically produce, 4,4'-dichlorobiphenyl, it is difficult to see how (richloro- and tctrachlorobiphenyls could be formed as suggested by Maugh (1973). Moreover, Kerner et at. (1972) could detect only b's-(/)-chlorophcnyl)-chloroethylene (DDMU) after ultraviolet irradiation of DDL Because of the ecological importance of these possible rearrangements we have reinvesti gated the behavior of DDE in the mode! ecosystem (Metcalf et at. 1971) to determine if my PCB-like products could be formed under the simulated daylight of the model ecosystem (5000 foot candles) in an environmental chamber. The radioautograph show- ci Cl Ci(( * Cl std s n?0 hyd. utogram of TLC plate cont of water and organisms .I'^'.^trachlorobiphenyl. *)* M (mosquito larva), S D (Hf radiolabeled com- hyd. Fig- 2C. Radioautogram of TLC plate con taining extracts of water and organisms treated with 2,4,5,2' .S'-penlachlorobiphenyt. A (alga). F (fish), M (mosquito larva), S (snail) and STD (C-radiolabeied compound). Fig. 2D. Radioautogram of TLC plate con taining extracts of water and organisms treated with DDL. A (alga), F (fish), M (mosquito larva), S (snail) and STD 0 4C-radiolabcled compound). MGNS 085822 158 R. L. Metcalf el al. ing the fate of pure DDE is presented in Figure 2. When the extracts of water and organisms were developed on TLC plates with Skcilysolve B (hexane fraction) there was no trace of any ,4C labeled compounds with Rf values between 0.05 and 0.47 (DDE) or of any less polar materials with higher Rf values. Under these conditions, as shown in figure 2, triclilorobiphcnyl has Rf 0.43, tetrachlorobipheny! Rf 0.50, and pcntachlorobtphenyl Rf 0.53. Detection levels with the techniques used are approximately 0.1 ng (e.g., spot at aiga origin in DDE, Figure 2) or about 0.00002% of the total l4C applied. Thus under the model ecosystem conditions there is no evidence of formation of PCD isomers from DDE. DDE is extremely stable in the tissues of the living organisms of the model ecosystem and is stored as approximately 92, 93, 95, and 97% of the lotaJ 14C in snail, aiga, fish, and mosquito larva. The percent of unextractable |4C in these organisms tanged hum 0.10 to 0.93 (Table III). The B.l. value for DDE in fish was 0.049 and the E.M. value 12,037 (compared with 0.032 and 27,358 found by Metcalf et al. (1971). From these values it is apparent that DDE is a more stable environmental pollutant than 2,4,5,2',5'pentachlorobiphcnyl (Table 1) which was stored in the organisms at 86 to 94% of the total radioactivity, with from 1.12 to 8.67% of unextractable 14C, and had a B.l. of 0.019 and an E.M. of 12,152 in fish. It is of interest that Sodergren (1973) using a model aquatic ecosystem found no major metabolic changes in DDE occurring in passage through a food chain into fish, although similar experiments with a polychlorinated biphenyl mixture (Clophcn A) showed that the lower fractions with low chlorine content were degraded when trans ported through the food chain, as was 2,5,2 -trichlorobiphcnyl m uui experiment:. Mow ever, in our studies (Figure 2, Table III) the water phase contained several polar radio- Table III. Distribution of DDE and degradation products in the model ecosystem h2o DDE equivalents (ppm) Oedogonium (!*) Physa (snail) Culcx (motquito) Gambusia (fish) Total iC 0.00384 DDE(Rf 0.49*) 0.00062 Unknown 1 (Rf 0.05) 0.00009 Polar (Rf 0.0) 0.00223 Unextractable ' 0.0009 7.4720 6.9759 0.4881 0.0080 38.1958 22.5325 0.8035 1.1612 0.3616 24.8588 36.8223 1.2448 0.1087 7.8653 7.4632 0.3746 0.0275 TLC with hexane (Skellysolve B, bp 60-68C). WON* "Ox tract* of water and s fraction) there was * and 0.47 (DDE) m dilions, shown in i.ifld pentachlorobi[tpioximatciy 0,1 ng he total' 4C applied, of formation of PCB the model ecosystem C in snail, alga, fish, rganism* ranged from 19 and the E M. value f, (1971). Front these utant than 2,4,5,2 ,5 k at 86 to 94% of the C, and had a B.l. of Degradation of Polychlorinated Biphenyls Compared with DDE 159 labeled degradation products. These were resolved on silica gel into at least 11 distinct compounds using a solvent of benzene:dioxane:acctic acid (90:30:1) and we are presently attempting to identify the pathway of DDE degradation in the environment. Biomass Recovery. To determine the relative availability of the various organisms of the model ecosystem as reservoirs for the bioaccumulation of the micropollutants studied, the total amounts of ,4CHabelcd products recovered from the principal organisms of the model ecosystems treated with tri-, tetra-, and pentachloro-PCB's, and DDE were evaluated as shown in Table IV. The evaluations were made on the basis of total re covery of the applied pollutant, recovery of the maximum amount of pollutant in water (Figure 1) for each of the four principal organisms, alga, snail, mosquito, and fish; and biomass recovery (four organisms) of the total amount of pollutant lost from water (Figure 1). The figures of Table IV are very revealing in terms of the biodegradability of the various compounds. The highest recoveries of the *4C lost from solution were ob tained from the organisms with DDE, 65.8%, and pentachlorobiphenyl, 57 2%. With tetrachiorobiphenyl recoveries of 8.7% were still substantial, but with trichlorobiphcnyi (recovery 0.45%) the compound was nearly completely degraded and excreted. t ecosystem found no i food chain into fish, mixture (Cloplrcn A) 5 degraded when uansour experiments. Howd Kveral polar radio- ' . . products >pm) ._______________ Gambusta (mosquito) (fish) 24.8588 36.8223 7.8653 7.4632 1.2448 0.1087 0.3746 0.0275 , Table IV. Biomass recovery of chlorinated biphenyls, and DDE from organisms of model ecosystem % Recovery Alga Snail Mosquito Fish trichlorobiphenyl ,4C in solution 0.18 0.015 total 4C 0.033 0.0028 (biomass) of 14C lost from solution------- 0.45 0.0017 0.00032 tetrachiorobiphenyl >4C in solution 3.33 1.04 0.23 total 14C 0.28 0.088 0.019 (biomass) of 14C lost from solution------- 8.7 pen tachlorobipheny1 14C in solution 4.57 19.0 2.32 total 'C 0.74 3.06 0.37 (biomass) of 14C lost from solution------- 57.2 ,4C in solution 22.4 4.03 total '<C 0.24 0.044 (biomass) of ,4C lost from solution-------6S.8 DDE 2.25 0.055 0.12 0.021 1.91 0.16 11.8 1.90 20.2 0.22 MOMS 0650 Z*t W 160 R. L. Metcalf n at. Degradation in Salt Marsh Caterpillar. This animal was chosen, after considerable study, as the dispersing agent for the model ecosystem because it was able to ingest a large variety of otganic compounds without apparent injury (Metcalf et at. 1973). The effects of passage of the PCB isomers through the insect are of interest as representing the First stage in the biodegradation of these compounds. Figure 3 shows radio autographs of TLC plates of extracts of feces and body homogenates from larvae feeding on about 30 /jg of 4C PCB incorporated in a synthetic diet. Figure 3 and the quantitative tri-Cl tetra-CI penta-CI Fig. 3. Radioautogram of TLC plate containing extracts of bodies and feces of salt marsh caterpillar larvae fed ,4C-labeled 2,5,2 -tri-, 2,5,2 ,5 -tctra-, and 2,4,5,2',5 -pentachlorobiphenyls. B (body homogenate), and F (fecal excreta). MONS Oa5tt25 , sftct considerable ni able lo infest a :a|f n 11. 1973). The terest as representing jure 3 show* radiops from larvae feeding 3 and the quantitative \ i I i 1 i Lei F odies and feces of salt marsh and J,4,S,2'.S'-pentaehloro- Degradation of Polychlorinated Diphenyls Compared with DDE 161 evaluation of the radioactivity in the various spots shown in Table V demonstrate con clusively the much greater degradability of the trichlorobiphcnyl over the tet.achlorobiphenyi and pcntachlorobiphenyi. With the trichioro-compound the caterpillar feces con tained 91% of the recovered 14C, with the remainder in the body homogenate, while with the tetrachloro- and pentachlorobiphenyls, the feces contained 21% and 24% of the radioactivity. The unknown (Rf 0.05) found in feces after trichlorobiphcnyl is probably the principal hydroxylated degradation product leading to the very large amount of polar radioactivity. Whereas only low levels of trichlorobiphcnyl were retained in the salt marsh calcrpilfar body, with tetrachloro- and pentachlorobiphcnyi the major portion of > 4C was retained in the insect body. Table V. Metabolism of 1 *C radiolabeled compounds by salt marsh caterpillar Body Feces A. 2,5,2,-lrichlorobphenyl total >4C (%) Unknown I (Rf 0.53*) trichlorobiphenyl (Rf 0.43) Unknown 11 (Rf 0.31) Unknown Hi (Rf 0.13) Unknown IV (Rr 0,05) Unknown V (Rf 0.02) Polar (Rf 0.0) B. 2,5.2\S,-tetrachlorobiphenyl total l4C(%) tctrachlorobiphenyl (Rf 0.50*) Unknown I (Rf 0.41) Unknown 11 (Rf 0.05) Unknown III (Rf 0.03) Polar (Rf 0.0) _C. 2,5,2\4,,5,-pentachlorobiphtnyl total 14C(%) pentachlorobiphenyi (Rf 0.534) Unknown I (Rf 0.46) Unknown U (Rf 0.39) Unknown 111 (Rf 0.03) Polar (Rr 0.0) D. 2,2-6ir-(p-chloropheny))-l,l-dichloroethylene (DDE) total 4C(%) DDE (Rf 0.49*) Polar (Rf 0.0) TLC with hexane (Skeltysolve B, bp 60-68C). 8.66 0.64 5.84 0.27 0.05 0.10 Oil 1.65 78 68 75.60 0.99 0.13 trace 1.96 75.86 74.00 0.74 0.62 0.08 0.42 80.59 76.88 3.71 91.34 8.91 0.37 0.12 4.67 0.92 76.35 21. il 15.08 1.36 0.20 4 64 24.14 20.70 0.74 0.56 0.08 2.06 19 41 19.37 0.04 HONS 085826 162 R. I,, Mclcalf ft at. DDE passed through the salt marsh caterpillar largely unchanged with 81% of the total radioactivity recovered retained in the body homogenate and 19% in (he fecal excreta (Table V). Ecological Magnification. The uptake and concentration of organic compounds by living organisms either directly or through food chains appears to be a function of two important factois, their high lipid solubility and low water solubility, re., a large lipid/ water partition coefficient; and their resistance to degradation by enzymatic processes, especially the multifunction oxidase enzymes (Metcalf et at. 1973). Hamelink er at. (1971) have suggested that the water insolubility of highly lipid-soluble compounds pro vides the driving force in producing lipid storage, through a series of simple partitionings from water to lipids. We have correlated the E.M. values for the PCB's and DDE from the fish of the model ecosystems with both water solubility (Table 11) in Figure 4, and with the octanol/water partition value (Table II) in Figure 5. Because the values for the PCB's and DDE fall closely together, the relationships have been extended using values for aniline, anisolc, benzoic acid, chlorobenzene, and nitrobenzene taken from other mode) ecosystem studies (Lu and Metcalf 1974). For the limited number of compounds included, the correlation between physical properties and biomagnification is excellent. The regression equation for log water solubility vs log E.M. (Figure 4) was: y = 4.4806 -0.4732 X : n = 9, r"-0.9677 Log water solubility - ppb Fig. 4. Plot of log E.M. (ecological magnification) for fish log water solubility (ppb). mqns 095327 nged with 81% of the and 19% in the fecal irganlc compounds by i be i function of two ility, ic., a large lipid/ y enzymatic processes, 973). Ilimclink et at. olublc compounds pi tv of simple partitionings ;B's and DDE from the ) in Figure 4, and with use the values for the extended using values 'ene taken from other number of compounds unification is excellent. 4) was: 577 Degradation of Polychlorinated Biphenyls Compared with DDE 163 The rcEress*nne(!uation frlog partition coefficient (Hansch's n) vs. log E M. (Figure S) was: y =- 0.7504+ 1.1587 X : n = 9, r * 0.9771 Thus for the organic compounds studied, the properties of water solubility and octanol/water partition coefficient appear to provide a realistic estimate of the biological magnification found in living organisms. Ji------------- 1 JO 7.0 8.0 iter solubility (ppb). Log partition coefficient Fig. S. Plot of log E.M. (ecological magnification) for fish vx. log octanol/water partition coefficient. Acknowledgments This research was supported in part by research grants from the U. S. Department of Interior, Office of Water Resources Research through the University of Illinois Water Resources Center Project B-050, Illinois; the National Science Foundation Grant Gl 39843X, the U. S. Environmental Protection Agency Grant R802022 and Grant R800736, and the Bureau of Veterinary Medicine, Food and Drug Administration. Contract FDA 72-116. HONS 06562a r7 164 R. L. Metcalf et at. References Costs, J. R., R. L. Metcalf, and 1. P. Kapoor: Metabolism of the methoxychlor isostere, dianisylneopentane in mouse, insects, and a model ecosystem. Pesticide Biochcm. Physiol. 4, 201(1974). Datta, P. R.: In vivo detoxication of p.p-DDT via p,p-DDE top.p'-DDA in rats. Ind. Med. 39, 190(1970). Hameiink, J. L., R. C. Waybrant, and R. C. Ball: A proposal: exchange equilibria control the degree chlorinated hydrocarbons are biologically magnified in lentic environ ments. Trans. Am. Fisheries Soc. 100, 207 (1971). Hutzinger, O., D. M. Nash, S. Safe, A. S. W. DeFreitas, R. J. Norstrom, D. J. 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