Document ZJ7GKw2J5dpDKmj490oE6zOLd

KS Ul I 'll 11 Til - li-1 i m**^^*. A ,w|i ....... , carbon tetrachloridcI, 495 (J 969). in brains and bodies of (1966). Jrniuni, and lead. Ann. ibilization of DDT by wobenzcnc in Japanese production, and tissue and gross development '1). 20, 1974 1$ fmwrr LABORATORY MODEL ECOSYSTEM STUDIES OF THE DEGRADATION AND FATE OF RADIOLABELED TRI-, TETRA-, AND PENTACHLOROBIPHENYL COMPARED WITH DDE ROBERT L. METCALF, JAMES R. SANBORN, PO-YUNG LU and DONALD NYE Department of Entomology and Environmental Studies Institute, University of Illinois and Illinois Natural History Survey, Urbana-Champaign Urbanat Illinois 6180J Radiolabeled tri-, tetra-, and pentachlorobiphenyls (PCB) and DDE were studied in a laboratory model ecosystem for degradation pathways, and biomagnification in alga, snail, mosquito, and fish. Trichlorobiphenyl was degraded in ail the organ isms of the model ecosystem much more rapidly than tetrachloro- and pentachlorobiphenyl. 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, dieldrin, endrin, mirex, lindane, and hexachlorobenzenc (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 biomagnification and food chain concentration, and (4) their comparative biodegradability; all in organisms of five phyla linked in several food chains. This information has proved of value in characterizing the potential environ mental pollutant effects of candidate insecticides (Kapoor et al. 1973, Coats ef al. 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 dichlorodiphcnyldichloroethylene (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. 1971). The >4C radio-labeled compounds were applied quantita tively from acetone solution at 5.0 mg (or ca. one kg per ha) to Sorghum vulgare seedlings grown in the terrestrial portion. The treated leaves were consumed by fourth instar salt Archive! of Environmental Contamination and Tonicotogy. Vol. 3. No 2. 1975 1975 by Springci-Verlig New York Iik. 151 a'nmBpW'pBWHUUI UUIR DSW 031486 STLCOPCB4015448 152 R. L. Metcalf el a!. marsh caterpillar larvae Estigmene acrea, whose activities and fecal products contaminated the aquatic portion of the system. The radiolabeled products were transferred through several food chains, e.g., alga (<Oedogonium cardiacutn) -* snail (Physa)\ plankton -* water flea (Daphnia magna) -* mosquito (Culex pipiens quinquefasciatus) -* fish {Gambusia affinis). After 33 days in an environmental chamber at 26C and a 12-hr photoperiod at 5,000 foot candles simulated daylight, the 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 radioaulography on no-screen x-ray film. Liquid scintillation counting of the individual components was done in cocktail D (5 g PPO and 10Q 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 14C02 by the Schoniger oxygen flask technique (Kelly et al. 1961) to determine the uncxtractable 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 14C-labeled PCB's were obtained from Mallinkrodt.St. Louis, Missouri. They were: 2,5,2'-trichJorobiphenyl (2,5-dichlorophenylring-UL-i 4C), 9.91 mCi per mmole with > 98% radiopurity and 41.5% Cl, and a principal constituent of Aioclor 1242 (Webb and McCall 1972); 2,5,2\5'-tetrachlorobiphcnyl (ring-UL* 4C), 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',5,-pcntachlorobiphenyl (2',5'-dichlorophenyl-ring-UL1 'C), 9.87 mCi per mmole with > 98% radio purity and 54.4% Cl, a principal constituent of Aroclor 1254 (Webb and McCall 1972). I4C labeled 2,2-bK'(/?-chlorophenyl)-l ,1-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 K0I1, and purifying on a silicic acid column with hexane elution to 99% radiopurity. Results PCB's. The movement of 14C 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 1) were in the ppb range, below the water solubility of the compounds as determined by radiotracer technique (Table II). 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 *4C in the spots on the TLC plates. The results for the three PCB's are also expressed in DSW 031487 STLCOPCB4015449 roducls contaminated ood chains, e.g., alga i (Dophnia tnagna) -* i ). After 33 days in an oot candles simulated 14C-radiolabelcd comker(E. Merck GF-254) lion counting of the naphthalene in dioxanc anncls ratio quenching combuslion to 14C02 tennine the uncxtiactJ components on the wn standards and by ; were obtained from yl (2,5-dichlorophcnyl1.5% Cl, and a principal ,5-telrachlorobipbcnyl 8.7% Cl, and a principal 4.5.2'.5'-pcntachlorobi(le with > 98% radio ebb and McCall 1972). )E) was prepared from e, Amersham, England, lie KOH, and purifying Degradation of Polychlorinated Biphenyls Compared with DDE 153 Table II in terms of ecological magnification (E.M.) (ppm in organism/ppm in water) and of biodegradability index (B.I.) (ppm polar degradation products/ppm nonpolar products). The E.M. values for the parent compounds increased substantially with the number of chlorine atoms, from trichlorobiphenyl (41.5% Cl) to tetrachlorobiphenyl (48.7% Cl) to pentachlorobiphenyl (54.4% Cl). Conversely the B.I. 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, arc presumably hydroxylated PCB compounds and the polar radioactivity (Rf 0.0) is thought to consist of conjugates of these compounds. Watlnotcr er al. (1973) have found 4-chloro 4'-hydroxybiphcnyl as a metabolite of 4-chlorobiphenyI from soil fungus. Rhizopux 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'-tetrachlorobiphcnyl in the rat. Hutzinger et al. (1972) have shown that rat and pigeon could hyd.oxylate 2,5,2',5'-lelrachlorobiphenyl 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 slowly hydroxylatc this tetrachlorobiphenyl. nts into the water phase ltd biphenyls reached a itmcnt and the levels of lisms of the system. The | were in the ppb range, y radiotracer technique model system after TLC tative distribution of the ?B's are also expressed in Fig. I. Movement of total ,4C radioactivity model ecosystem and uptake by organisms. from plants into the water phase of (he I DSW 031488 STLCOPCB4015450 Table 1. Distribution of chlorinated biphenyls and their degradation products in the model ecosystem HjO Chlorinated biphenyl equivalents (ppm) Oedogonium (alga) Physa (snail) Culex Gambusia (mosquito) (fish) 1. 2,5,2'-trichlorobiphenyl total 14C Unknown 1 (Rf 0.66) trichlorobiphenyl (Rf 0.S6) Unknown II (Rf 0.23) Unknown II! (Rf 0.10) Unknown IV (Rr 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\s'-lctrachloro biphenyl total 1 4C tetrachlorobiphenyi (Rf 0.48) Unknown 1 (Rf 0,23) Unknown II (Rr 0.04) Polar (Rr 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 III. 2,5I2,,4,,5,-pentachlorobiphenyl total 14C pentachlorobiphenyl (Rf 0.55*) Unknown I (Rf 0.46) Unknown II (Rf 0.39) Unknown III (Rf 0.21) Unknown IV (Rr 0.04) Unknown V (Rf 0.02) Polar (Rf 0.0) Unextractable 0.04340 0.00985 - 0.00020 0.00015 0.00030 0.00385 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 8.6210 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 2.3610 1.4350 154 DSW 031489 aaaowinw STLCOPCB4015451 Table II. Ecological magnification (E.M.) and Biodegradability index (B.I.) of PCB's and DDE compared with water solubility and partition coefficient Chemical H^O solubility (ppb) Partition coefficient Ecological magnification (E.M.) Alga Snail Mosquito Fish Biodegradability 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 26,037 5,464 59,629 17,345 12,152 0.029 0.027 0.0134 0.019 DDE o tA sc o OJ Jr* >0 o 1.3 18,893 11,251 36,342 59,390 12,037 0.069 0.049 0.033 0.050 I STLCOPCB4015452 l*rt*nlAl -j' Ji ******-*Ti "J .'fci. 156 R. L. Metcalf et at. Tlic pcntachlorobiphciiyl 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 cl al. 1973) and this suggests (hat the two compounds should behave similarly in the environ ment (Risebrough et al. 1968). Properties of the tetrachlorobiphcnyl were similar to those of the pcntachlorobiphenyl (Figure 2) but the trichlorobiphcnyl was much more degtadablc. A prominent degradative product (Rr 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 1 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 in alga and in the snail and mosquito which are alga feeders suggests that it might be formed by photo chemical 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 Ct Cl Ct Cl Cl ct Cl hyd. Fig. 2A. Radioautogram of TLC plate con taining extracts of water and organisms treated with 2,5,2 -trichlorobiphenyl. A (alga), F (fish), M (mosquito larva), S (snail) and STD (* 4C-radiolabe]ed com pound). hyd. Fig. 2B. Radioautogram of TLC plate con taining extracts of water and organisms treated with 2,5,2 ,5 -tetrachlorohiphenyl. A (alga), F (fish), M (mosquito larva), S (snail) and STD ('4C-radiolabeled com pound). DSW 031491 min Fil! l.iii tri'i pile la r v Ial*< STLCOPCB4015453 Hfc-uiS*-1'-'1- J , S''***- tMk fish and snail is very 0.044 (Kapoor ct al. lilaily in the environ- tenyl were similar to lenyl was much more d in alga, snail, and nd. This compound is CB isomers. As shown i 126.480X in snail, is inis in alga and in the be formed by photo>und forms slowly and doiobiphcnyl by alga, it appeared in alga in ! : j I i , j t \ , ; i Ct Cl Degradation of Polychlorinated Biphenyls Compared with DDL 157 14-day studies. To data we have been unsuccessful in identifying the unknown by mass spectrometry. DDE. This compound has been implicated as a possible environmental precursor of PCB isomers lluough photoxidalion reactions involving radical rearrangements to 3,6-dichlorofluorcnone intermediates (Plimmer et al. 1970, Pcakall and Lincer 1970, Moilancn and Crosby 1973). Although such rearrangements could logically produce, 4,4'-dichlorobiphenyl, it is difficult to see how tricliloro- and tetrachlorobiphenyls could be formed as suggested by Maugh (1973). Moreover, Kemer et al. (1972) could detect only />/s-(/7-chlorophcnyl)-chloroethylene (DDMU) after ultraviolet irradiation of DDE Because of the ecological importance of these possible rearrangements we have reinvesti gated the behavior of DDE in the model ecosystem (Metcalf et al. 1971) to determine if any PCB-like products could be formed under the simulated daylight of the model ecosystem (5000 foot candles) in an environmental chamber. The radioautograph show- ct * Cl Cl Cl Cl utogiam of TLC plate con i of water and organisms ,2',5'-tctrachlorobiphenyl. Ji), M (mosquito larva), S |D (> *C-;adiolabeled com- Fig. 2C. Radioautogram of TLC plate con taining extracts of water and organisms treated with 2,4,5,2',5,-pentachlorobiphenyl. A (alga), F (fish), M (mosquito larva), S (snail) and STD (*^-radio labeled compound). A F M STD S HzO Fig. 2D. Radioaulogram of TLC plate con taining extracts of water and organisms treated with DDL. A (alga), F (fish), M (mosquito larva), S (snail) and STD (' 4C-radiolabeled compound). DSW 031492 I STLCOPCB4015454 158 R. L. Melcalf 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 Skellysolve B (hexane fraction) there was no trace of any I4C labeled compounds with Rf values between 0.05 and 0.47 (DDE) or of any less polar materials with higher Rr values. Under these conditions, as shown in Figure 2, trichlorobipheny! has Rf 0.43, tetrachlorobiphenyl Rf 0.50, and pcntachlorobiphcnyl Rf 0.53. Detection levels with the techniques used are approximately 0.1 ng (e.gspot at alga origin in DDE, Figure 2) or about 0.00002% of the total |4C applied. Titus under the model ecosystem conditions there is no evidence of formation of PCB 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 total 14C in snail, alga, fish, and mosquito larva. The percent of unextractable 14C in these organisms ranged from 0.10 to 0.93 (Table 111). 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). Prom these values it is apparent that DDE is a more stable environmental pollutant than 2,4,5,2 ,5'pcntachlorobiphenyl (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 |4C, and had a B.l. of 0.019 and an E.M. of 12,152 in fish. It is of interest that Sodergrcn (1973) using a model aquatic ecosystem found no major melabolic 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 (he food chain, as was 2,5,2 -trichlorobiplienyl in urn experiments. Hew 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 (alga) (snail) Culex (mosquito) Gambusia (fish) Total HC 0.00384 DDE (Rf 0.49*) 0.00062 Unknown I (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 60-68 C). .iiukiiii 11 11 l DSW 031493 ([ hi <! , lb t.n hi (k STLCOPCB4015455 tracts of water and * fraction) there was 5 and 0.47 (DDE) or iditions, as shown in ), and pcntachlorobipproximalciy O.i ng he total > 4C applied, of formation of PCB the model ecosystem *C. in snail, alga, fish, rganisms ranged from 19 and tire E.M. value I. (1971). From these utanl than 2,4,5,2',5's at 86 to 94% of the 'C, and had a B.l. of Degradation of Polychlorinated Biphenyls Compared with DDF 159 labeled degradation products. These were resolved on silica gel into at least 11 distinct compounds using a solvent of benzcne:dioxane: acetic 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 14C-labclcd products recovered from the principal organisms of the model ecosystems treated with tri-, tetra-, and pentacldoro-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 14C lost from solution were ob tained from the organisms with DDE, 65.8%, and pentachlorobiphenyl, 57.2% With tetracldorobiphenyl recoveries of 8.7% were still substantial, but with trichlorobiphcnyl (recovery 0.45%) the compound was nearly completely degraded and excreted. c ecosystem found no i food chain into fish, mixture (Clopltcn A) r degraded when Iransour experiments. Howned several polar rauio- \products >pm) Cu/cx Garnhusia (mosquito) (fish) 24.8588 36.8223 7.8653 7.4632 1 - ; 1.2448 0.1087 0.3746 0.0275 -------- - ; i Table IV. Biomass recovery of chlorinated biphenyls, and DDE from organisms of model ecosystem % Recovery Alga Snail Mosquito Fish trichlorobiphenyl 14C in solution 0.18 0.015 total 1 4C JD.033 0.0028 (biomass) of 14C lost from solution ---- 0.45 0.0017 0.00032 tetrachloro b iph cnyl *4C in solution 3.33 1.04 0.23 total 14C 0.28 0.088 0.019 (biomass) of ,4C lost from solution ---- 8.7 pentachlorobiphenyl 14C in solution 4.57 19.0 2.32 total >4C 0.74 3.06 0.37 (biomass) of 14C lost from solution -- -57.2 ,4C in solution 22.4 4.03 total '4C 0.24 0.044 (biomass) of ,4C lost from solution ---- 65.8 DDE 2.25 0.055 0.12 0.021 1.91 0.16 11.8 1.90 20.2 0.22 V.1J<| PWIPW DSW 031494 i STLCOPCB4015456 __________ / i--lirvitfm. .At., !60 R. L. Metcalf et al. 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 organic compounds without apparent injury (Metcalf et al. 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 pg of 14C PCB incorporated in a synthetic diet. Figure 3 and the quantitative tri-CI tetrs-CI penta-CI Fig. 3. Radioautogram of TLC plate containing extracts of bodies and feces of salt marsh caterpillar larvae fed ,4C-)abeled 2,5,2-tri-, 2,5,2 ,5'-ictra-, and 2,4,5,2 ,5 -pentachlorobiphenyls. B (body homogenate), and F (fecal excreta). DSW 031495 STLCOPCB4015457 M niiimiiilliA'ii'ffi' ' ' iiFHn`i(Tiii?rrr j i i I i I odies and feces of salt roars)) and 2,4,5,2,,S'-pentachloro- Dcgradation of Polychlorinated Diphenyls Compared with DDE 101 evaluation of the radioactivity in the various spots shown in Table V demonstrate con clusively the much greater degradability of the tricldorobiphcnyl over the tctiachlorobiphenyl and pcntachlorobiphenyl. With the trichloro-compound the caterpillar feces con tained 91% of the recovered l4C, 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 tricldorobiphcnyl is probably the principal hydroxylated degradation product leading to the very laigc amount of polar radioactivity. Whereas only low levels of trichlorobipheny! were retained in the salt marsh caterpillar body, with tetrachloro- and pentachlorobiphenyl the major portion of 14C was retained in the insect body. Table V. Metabolism of 14C radiolabeled compounds by salt marsh caterpillar* Body Feces A. 2,5.2,-lrichlorobiphenyt total ,4C (%) Unknown 1 (Rr 0.53*) trichlorobiphenyl (Rf 0.43) Unknown II (Rf 0.31) Unknown 111 (Rf 0.13) Unknown IV (Rf 0.05) Unknown V (Rf 0.02) Polar (Rf 0.0) B. 2,5,2',5,-tetrachlorobiphenyl total t4C(%) tetrachlorobiphenyl (Rf 0.50*) Unknown I (Rf 0.41) Unknown II (Rf 0.05) Unknown III (Rf 0.03) Polar (Rf 0.0) C. 2,5I2,,4,,5,-pentachlorobiphtnyl total ,4C(%) pentachlorobiphenyl (Rf 0.53a) Unknown I (Rf 0.46) Unknown II (Rf 0.39) . Unknown III (Rf 0.03) Polar (Rr 0.0) D. 2,2-fcis-(p-chlorophenyl)-l,l-dichloroethyIene (DDE) total ,4C(%) DDE (Rf 0.49s) Polar (Rf 0.0) *TLC with hexane (Skellysolve B, bp 60-68C). 8.66 0.64 5.84 0.27 0.05 0.10 0.11 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 21.32 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 vm DSW 031496 STLCOPCB4015458 'It L J62 R. E. Metcalfe/ al. DDE passed through the salt marsh caterpillar largely unchanged with 81% of the total radioactivity recovered retained in the body homogenate and 19% in the fecal excreta (Table V). Ecological Magnification. The uptake and concentration of organic compounds by living organisms cither directly or through food chains appears to be a function of two important factois, their high lipid solubility and low water solubility, i.e., a large lipid/ water partition coefficient; and their resistance to degradation by enzymatic processes, especially the multifunction oxidase enzymes (Metcalf et al. 1973). Hamelink et al. (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 II) in Figure 4, and with the octanol/watcr 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 model ecosystem studies (Lu and Metcalf 1974). For the limited numbci 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 1i cc i In R. Cl R: C< STLCOPCB4015459 .u^., ............................ iHIllMHin || aged with 81% of the and 19% in the fecal organic compounds by ) be a function of Iwo ility, i.c., a large lipid/ y enzymatic processes, 973). Hamclink et al. oluble compounds pro of simple partitionings ;B's and DDE from the ) in Figure 4, and with use the values for the extended using values renc taken from oilier number of compounds unification is excellent. 4) was: 377 I Degradation of Polychlorinated Biphenyls Compared with DDE 163 The regression equation for log partition coefficient (Hansch's a) vs. log E.M. (Figure 5) was: y = - 0.7504 +1.1587 X : n = 9, r = 0.9771 Thus for the organic compounds studied, tire properties of water solubility and oclanol/water partition coefficient appear to provide a realistic estimate of the biological magnification found in living organisms. aniline JI------------ 1 GO 7.0 8.0 | tcr solubility (ppb). I I! ] I Log partition coefficient Fig. 5. Plot of log E.M. (ecological magnification) for fish i't. log octanol/water partition coefficient. Acknowledgmen ts 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 GI 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. DSW 031498 STLCOPCB4015460 164 R. L. Metcalf ft at. References Costs, J. R., R. L. Metcalf, and I. P. Kapoor: Metabolism of the metlioxychlor isostere, dianisylneopentane in mouse, insects, and a model ecosystem. Pesticide Biochem. Physiol. 4, 201 (1974). Datta, P. R.: In vivo detoxication of p.p'-DDT via p,p'-DDE to p.p'-DDA in rats. Ind. Med. 39, 190(1970). Hamelink, J. L., R. C. Waybrant, and R. C. Ball: A proposal: exchange equilibria control the degree chlorinated hydrocarbons are biologically magnified in lentic cnvironments. Trans. Am. Fisheries Soc. 100, 207 (1971). Hutzinger, O., D. M. Nash, S. Safe, A. S. W. DeFreitas, R. J. 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