Document QJDeN1aR23DgXxrygBerw9m4E

? MJ carbon tetrachloride,495(1969). n brains and bodies of (1966). imium, and lead. Ann. bilization of DDT by : | ` j ! 5 r robenzene in Japanese jroduction, and tissue and gross d evelopmcnt 'I)- : | I : i 20,1974 tt r 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 Deportment of Entomology and Environmental Studies Institute, University of Illinois . and Illinois Natural History Survey, Urbana-Champaign - Urbana, Illinois 61801 Radiolabeled tri-, tetra-, and pcntachlorobiphenyls (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 all the organ isms of the model ecosystem much more rapidly than tetrachloro- and pcntachlorobiphenyl. 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 ecosvsiem previously described (Metcali et a/. 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 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 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 etal. 1973, Coats et 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 (PCI)'s), and of dichlorodiphcnyldichlorocthylcnc (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 l4C 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 Archives of Environmental Contamination nd Toxicology, Vol. 3. No. 2, 1975 1975 by Springer-Verlag New York Inc. 151 '........` "" ' '' _' ' -' '" 0SW343^8 \ STLCOPCB4083671 152 R. L. Metcalf et al. 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 i . (Oedogonium cardiacum) -* 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-radiolabcled 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 dioxane ] 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 unextractablc 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. 1 Radiolabeled compounds. The individual 14C-labeled PCB's were obtained from Mallinkrodt, St. Louis, Missouri. They were: 2,5,2,-trichlorobiphenyl (2,5-dichlorophenylring-UL-i 4C), 9.91 mCi per mmole with > 98% radiopurity and 41.5% Cl, and a principal constituent of Aroclor 1242 (Webb and McCall 1972); 2,5,2',5'-tetrachlorobiphenyl (ring-UI^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\5'-pentachlorobipheny! (2,,5,-dich1r,rr*pi'''ny,-r'r>o-lll,i'iri. 9.87 mCi per mmole with > y87c raaiopurity and 54.4% Cl, a principal constituent of Aroclor 1254 (Webb and McCall 1972). 14C labeled 2,2-bfs-(p-chlorophenyl)-l ,1-dichloroethylene (DDE) was prepared from 14C-ring-UL p.p'-DDT obtained from the Radiochemical Centre, Amersham, England, 5.48 mCi per mmole, by dehydrochlorinating with 1.0 M alcoholic KOH, 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 Figuie 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. 1 be levels of the chloiinated 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 I 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 STLCOPCB4083672 >roducts contaminated food chains, e.g., alga a (Daphnia magna) -* rs). After 33 days in an foot candles simulated ,4C-radiolabeled comker (E. Merck GF-254) tion counting of the aaphthalenc in dioxane lannels ratio quenching combustion to ,4C02 Pennine the unextractd components on the wn standards and by ; were obtained from iyl (2,5-dichlorophenylIJS% G, and a principal '.S'-letrachlorobiphenyl 8.7% Cl, and a principal >ie \vun yt>70 lauiuebb and McCall 1972). 9E) was prepared from e, Amersham, England, >lic KOH, and purifying Degradation of Polychlorinated Biphenyls Compared with DDE 153 Tna.blefn,in,term! oncological magnification (E.M.) (ppm in organism/ppm in water) and of biodegradabihty index (B.I.) (ppm polar degradation products/ppm nonpolar products) The E.M. values for the parent compounds increased substantially with the ! T M0ni,S- ?0m t/ich,0r0biphenyl (41-5%C1) to tetrachlorobiphcnyl (48.7% Cl) to pentachlorobiphenyl (54.4% Cl). Conversely the B.I. values decreased with incrcasrng degree of chlorine. This consistent and regular behavior gives added confidence that these parameters are ecologically significant (see Kapoor et al. 1973) and must be a function of the number of C-H bonds available for hydroxylation by microsomal oxida tions m the various organisms. The spots of low Rf value (0.02-0.06) Figure 2 are presumably hydroxylated PCB compounds and the polar radioactivity (Rf 0.0) is thought to consist of conjugates of these compounds. Wallnofer etal. (1973) have found 4-chloro4 -hydroxybiphcnyl as a metabolite of 4-chlorobiphenyl from soil fungus, Rhizopus japomeus Yoshimura and Yammamoto (1973) have reported the 5-hydroxylated deriva- 5TM f a"d }bc 3-hydroxylated derivative as the minor excretion product of 2,4,3 ,4 -tetrachlorobiphenyl in the rat. Hutzinger et al. (1972) have shown that rat and pigeon could hydroxylate 2,5,2,5'-tetrachlorobiphenyl but they could not detect hydroxylated metabolites in brook trout. However, the amounts of polar material in SSlbSy,2' `hat " " >b`e * slow'y hyd'ra>"s,e " ints into the water phase <tcd biphenyls reached a itmcnt and the levels of riisms of the system. The ) were in the ppb range, >y radiotracer technique : model system after TLC itative distribution of the CB's arc also expressed in Fig. I. Movement of total >4C radioactivity model ecosystem and uptake by organisms. from plants into the water phase of the ! .. -------------------------- .......... | .................... ,, '__________ DSW 341120 ' STLCOPCB4083673 . 1 ': * `5 ;] ; i I 1 5 .i -A... Table I. Distribution of chlorinated biphenyls and their degradation products in the model ecosystem Chlorinated biphenyl equivalents (ppm) - Oedogonium Physa Culex Gambusia H20 (alga) (snail) (mosquito) (fish) I. 2,5,2'-trichlorobiphenyl total 14C 0.03845 Unknown I (Rf0.66") trichlorobiphenyl (Rf 0.56) Unknown II (Rf 0.23)' Unknown III (Rf 0.10) Unknown IV (Rf 0.06) Unknown V (Rf 0.04) Unknown VI (Rf 0.03) Polar (Rf 0.0) Unextractable 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'-tetrachloro biphenyl total14C ptTarhlorobiphenyl (t> . r\ /ica'* Unknown I (Rf 0.23) Unknown II (Rf 0.04) Polar (Rf 0.0) Unextractable 0.02065 n nmw 0.00005 0.00155 0.01225 0.00560 23.6845 21.5975 0.3220 0.1030 0.3275 1.3345 53.7465 4/.J//D 0.7560 0.4360 3.9850 1.2420 14.5335 1 4.o745 0.1070 0.9670 0.7850 15.5685 A < 0.0890 0.8545 0.3900 III. 2,5,2,,4',5,-pcnta- chlorobiphenyl total 14C pentachloro- biphenyl (Rr 0.55^) Unknown I (Rf 0.46) Unknown 11 (Rf 0.39) Unknown III (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 0.00385 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 119.7060 2.5380 0.5810 0.3285 .-- 0.7450 2.3610 1.4350 154 DSW 341121 STLCOPCB4083674 r degradation lents(ppm) Culex Cambusia 'mosquito) (fish) 2.7030 1.1995 0.1630 + 3.2055 0.2085 1.2800 0.1595 J ; -- - _ 0.4795 0.8610 - - __ 0.9985 0.5590 14.5335 12.6745 0.1070 -- 0.9670 0.7850 15.5685 14.2360 0.0890 ' 0.8545 0.3900 | | i If ! ; . 181.4565 127.6945 1* .j 1 170.8480 119.7060 j 2.4070 2.5380 ; 1.3195 0.5810 1.0520 0.3285 - 2.6745 3.1555 - 0.7450 2.3610 1.4350 i * '- . - ,1^ c O VO o VD O.v4 o iOn o 1 a JO 6 < ."c* 5,5 .ac 8 P S vo n m *n co co o do r<--* OJ ooo rrO*-J rof\ d <p coo i^on Ov (oN Ov vo dd o CO cs r*- js u* ^ vo* vo 0 --r m ^CS co ci min r4 o VO Ov 00 in CO CO o* r-* oC m S c II si!s- #$SJ OD 8 I min OV Ov n Ov <N Tj- r*^ VO CO m 0\ Ov vo CO in CO m 4 ov vi vo .4 in CO ov <N in ^ 4 `VCO .co> ooo CO vo o cs 00 r-" 00 r- CO CO On ^ 00 VO OO Bs ^.O I 8 & VO VO Ov on~ EC *u3 .CEV U CCuJ u*c-<* CO UCU U or-<t mCuU 0r1t ccOu w a o 155 1 s -v . . -1 v- 1 DSW 341122 STLCOPCB4083675 156 R. L. Metcalf et al. The pentachlorobiphenyl 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 et al. 1973) and this suggests that the two compounds should behave similarly in the environ ment (Risebrough et al. 1968). Properties of the tctrachlorobiphenyl were similar to those of the pentachlorobiphenyl (Figure 2) but the trichlorobiphenyl was much more degradable. A prominent degradative product (R,- 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, 106.3S2X 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 trichlorobiphenyl by alga, snail, daphnia, mosquito or fish (Metcalf and Lu 1973) although it appeared in alga in . tf j ; A F M STD S H20 H20 A F M SID S H20 H20 . hyd. .. ' . hyd. Fig. 2A. Radioautograin of TLC plate containing extracts of water and organisms treated with 2,5,2'.-trichlorobiphenyI. A (alga), F (fish), M (mosquito larva), S ' (snail) and STD (14C-radiolabcled compound). Fig. 2B. Radioautogram of TLC plate containing extracts of water and organisms treated with 2,5,2',S'-tctrachlorobiphenyl. A (alga), F (fish), M (mosquito larva), S (snail) and STD (14C-radiolabelcd compound). F ta tr pi la la DSW 341123 STLCOPCB4083676 fish and snail is very 0.044 (Kapoor et al. nilarly in the environhenyl were similar to tienyl was much more :d in alga, snail, and jnd. This compound is CB isomers. As shown d 126,480X in snail, is jnts in alga and in the : be formed by photo>und forms slowly and tilorobiphenyl by alga, 1 it appeared in alga in Degradation of Polychlorinated Biphenyls Compared with DDE 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 through photoxidation reactions involving radical rearrangements to 3,6-dichlorofluorenone intermediates (Plimmer et al. 1970, Peakall and Lincer 1970, Moilanen and Crosby 1973). Although such rearrangements could logically produce, 4,4,-dichlorobiphenyl, it is difficult to see how trichloro- and tetrachlorobiphenyls could be formed as suggested by Maugli (1973). Moreover, Kerner et al. (1972) could detect only h/s-(p-chloropheiiyI)-chlorocthylenc (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- I a i ,2',5'-tetrachlorobiphenyl. h), M (mosquito larva), S D (t4C-radiolabeled com- A F M STD S H20 H20 hyd. . Fig. 2C. Radioautogram of TLCplate con taining extracts of water and organisms treated with 2,4,5,2',5'-pentaclilorobiphenyl. A (alga), F (fish), M (mosquito larva), S (snail) and STD (14C-radiolabcled compound). Fig. 2D. Radioautogram of TLC plate con taining extracts of water and oigatiisms treated with DDE. A (alga), F (fish), M (mosquito larva), S (snail). and STD (,4C-radiolabcIed compound). I ".'j ".... 1 --IIHIIII III ^Ul'.'HUUUm1". ***"*^ "'"-If y rI . - 1 ip n .1I.L ........ ................ DSW 344424 STLCOPCB4083677 fc*5tttSM r -S: ,,*-M- 1SS R. L. Metcalf el dl. 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 14C 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, trichlorobiphcnyl has Rf 0.43, tetrachlorobiphenyl Rf 0.50, and pentachlorobiphenyl Rf 0.53. Detection levels with the techniques used are approximately 0.1 ng (e.g., spot at alga origin in DDE, Figure 2) or about 0.00002% of the total 14C applied. Thus 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 ,4C in these organisms ranged from 0.10 to 0.93 (Table III). The B.I. 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'pentachlorobiphenyl (Table I) 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.I. 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 (Clophen A) showed that the lower fractions with low chlorine content were degraded when trans ported through the food chain, as was 2t5,2'-trichlorobiphenyl in our experiments. How ever, in cur stud:;; (Figure 2, Teb! ,TI) u'mer phase contained several polar radio- Table III. Distribution of DDE and degradation products ' in the model ecosystem h2o DDE equivalents (ppm) Oedogonium rhysa (alga) (snail) Culcx (mosquito) Gambusia (fish) Total >4C 0.00384 DDE (Rf 0.49a) 0.00062 Unknown I (Rf 0.05) 0.00009 Polar (Rr 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). T t r c c ( b ( tl t; t( (r DSW 341125 STLCOPCB4083678 *"***** jcuacts of water and le fraction) there was )5 and 0.47 (DDE) or nditions, as shown in 0,arid pentachlorobijppioximately 0.1 ng the total 4C applied, of formation of PCB ,f the model ecosystem >4C in snail, alga, fish, organisms ranged from 49 and the E.M. value a!. (1971). From these lluiant than 2,4,5,2 ,5 as at 86 to 94% of the i4c, and had a B.I. of ic ecosystem found no a food chain into fish, 1 mixture (Clophen A) re degraded when transi our experiments. How- *rveral polar radio- : products ppm) Cuiex (mosquito) Gam bitsia (fish) 24.8588 36.8223 7.8653 7.4632 1.2448 0.1087 0.3746 0.0275 Degradation of Polychlorinated Biphenyls Compared with DDE 159 labeled degradation products. These were resolved on silica gel into at least 11 distinct compounds usinga solvent of benzene:dioxane:aceticacid(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-labeled 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 tetrachlorobiphenyl recoveries of 8.7% were still substantial, but with trichlorobiphenyl (recovery 0.45%) the compound was nearly completely degraded and excreted. Table IV. Biomass recovery of chlorinated biphenyls, and DDE from - organisms of model ecosystem ` % Recovery Alga Snail Mosquito Fish trtcrtiorobiphenyi 14C in solution 0.18 0.015 total 4C n0.033 0.0028 ' (biomass) of ,4C lost from solution ---- 0,45 0.0017 0.00032 'tetrachlorobiphenyl 14C in solution 3.33 ' 1.04 0.23 total ,4C 0.28 0.088 0.019 (biomass) of ,4C lost from solution --- 8.7 pen tachlorobiph enyl ,4C 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 14C 0.24 0.044 (biomass) of >4 C 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 *4-kJ DSW34112G STLCOPCB4083679 / . , - ^-^*1 160 R. L. Metcalf el 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 ct 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 /rg of 14C PCB incorporated in a synthetic diet. Figure 3 and the quantitative tri-CI tetra-CI penta-CI AMU M Fig. 3. Radioautogram of TLC plate containing extracts of bodies and feces of salt marsh caterpillar larvae fed 14C-labcled 2,5,2'-tri-, 2,5,2',5,-tetra-, and 2,4,5,2,,5'-pentachlorobiphenyls. B (body homogenate), and F (fecal excreta). .` . . . u jufwjn.gfMy'!v -j at iIi DSW 341127 STLCOPCB4083680 n, after considerable t was able to ingest a calf et al. 1973). The Merest as representing igure 3 shows radiotes from larvae feeding 3 and the quantitative i j > | { | ita-CI >odies and feces of salt marsh and 2,4,5,2',5-pcntachloro- Degradation of Polychlorinated Biphenyls 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 triclilorobiphcnyl over the tctrachlorobiphcnyl and pcntachlorobiphcnyl. With the trichloro-compound the caterpillar feces con tained 91% of the recovered 14C, with the remainder in the body homogenate, while with the tetrachloro- and pentaclilorobiphenyls, the feces contained 21% and 24% of the radioactivity. The unknown (Rf 0.05) found in feces after triclilorobiphcnyl is probably the principal hydroxylated degradation product leading to the very large amount of polar radioactivity. Whereas only low levels of trichlorobiphenyl were retained in the salt marsh caterpillar body, with tetrachlero- and pentachlorobiphenyl the major portion of ,4C was retained in the insect body. Table V. Metabolism of 14C radiolabeled compounds by salt marsh caterpillara Body Feces A. 2,5 ^-trichlorobiphenyl total 14C (%) Unknown 1 (Rf 0.53a) trichlorobiphenyl (Rf 0.43) Unknown If (Rf 0.31) Unknown III (Rf 0.13) Unknown IV (Rf 0.05) Unknown V (Rf 0.02) Polar (Rf 0.0) E. 2.5,2 ,5 -tetracmoroDiphciiyi iuLal ' tetrachlorobiphenyl (Rf 0.5 0a) Unknown I (Rf 0.41) ' Unknown II (Rf 0.05) Unknown III (Rf 0.03) Polar (Rf 0.0) . (%) . C. 2,5,2,,4f,5,-pentachlorobiphenyl total ,4C(%) pentachlorobiphenyl (Rf 0.53a) Unknown I (Rf 0.46) Unknown II (Rf 0.39) Unknown III (Rf 0.03) Polar (Rf 0.0) D. 2,2-h/s-(p-chlorophcnyl)-l,l-dichloroethylene (DDE) total <4C(%) * DDE (Rf 0.49a) . Polar (Rj 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 91.34 8.91 0.37 0.12 4.67 0.92 76.35 ' 71 32 13.00 1.36 0.20 4.64 24.14 20.70 0.74 0.56 . 0.08 2.06 80.59 76.88 3.71 19.41 19.37 0.04 jigipM, - : STLCOPCB4083681 .owa.1 .lVri-r*u V-fcVi*rfcftlnl ^w-JlTCr-W ., r^.. ^ 162 R. L. Metcalf et 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 either directly or through food chains appears to be a function of two important factors, 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). Hamclink 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 tire PCB's and DDE from the fish of the model ecosystems with both water solubility (Tabic II) 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, anisole, benzoic acid, chlorobenzene, and nitrobenzene taken from other model 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 ` O 73 O ys MUIJkllD DSW 341^29 STLCOPCB4083682 < . , >>. iV^feMiifirtiVrtiYifllfa mn~i>rfiWUfr .^V . y ?.. ' . ,. i. . ; *':*:>.Ml V anged with 81% of the e and 19% in the fecal organic compounds by to be a function of two bility, i.e., a large lipid/ by enzymatic processes, 1973). Hamelink et al. soluble compounds pro;s of simple partitionings `CB's and "DDE from the II) in Figure 4, and with ause the values for the n extended using values lzene taken from other J number of compounds Bonification is excellent, e 4) was: >677 ' | : i it ! Degradation of Polychlorinated Biphenyls Compared with DDE 163 Tlie regression equation for log partition coefficient (Hansch's rr) vs. log E.M. (Figure 5) was: .- y = -0.7504+ 1.1587X : -. 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. lie add1 me 0 iinliole enlline _!II 6.0 7.0 8.0 water solubility (ppb). Fig. 5. Plot of log E.M. (ecological magnification) for fish vs. 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 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 341130 STLCOPCB4083683 - - -- ------------- - ' " ~ " ilT lilll" H 1 *. r *1 J Jj sS*i 164 R. L. Metcalf ef at. - References Costs, J. R., R. L. Metcalf, and I. P. Kapoor: Metabolism of the methoxychlor isostere, dianisylncopentane 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). t Hamelink, 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. 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