Document 6xYxoLkJLomYJpBmkrkbo3QE

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 Urbana, Illinois 61801 Radiolabeled tri-, tetra-, and pentachlorobiphenyl (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 telrachloro- 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 (Metcalfe/ 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 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 belter understanding of the comparative environmental properties of trichloro-, telrachloro-, 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 terrcstrial-aqualic interface of pure white sand exactly as previously de scribed (Metcalf t'l 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 of Environmental Contamination Toxicology, VoL 3. No. 2, 1975 * by Springa-Vcrlug New York Inc. ] 51 V-. ; > &' - 'v : * Xr 'f ).; iN'.'-V T: s-i;* : .* . . . IV.-' T- <; .* i.. V-, i r I X. i l. ;t t D5W 025248 STLCOPCB4009203 152 R. L. Mclcalf ct ol. marsh caterpillar larvae Estigmene acrea, whose activities and fecal products contaminatei' the aquatic portion of the system. The radiolabeled products were transferred through several food chains, e.g., alga (iOedogonium cardiacum) -* snail (Physa)\ plankton water flea (Daphnia magna) -* mosquito (Culex pipiens quinquefnsciatus) -+ fish (Gambusia affinis). Afiei 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 '4C-radiolabeled 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 i4C(>2 by the Schoniger oxygen flask technique (Kelly et al. 1961) to determine the unextractable 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'-trichIorobiphenyl (2,5-dichlorophenylring-UL-14C), 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'-te(rachlorobiphenyl (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'-penlachlorobiphenyl (2',5'-dichlorophenyl-ring-UL-14C), 9.87 mCi per mmole with > 98% radio purity and S4.4% Cl, a principal constituent of Aroclor J254 (Webb and McCall 1972). ,4C labeled 2,2-f>/s-(p-chlorophenyl)-l ,1-dichloroethylene (DDE) was prepared from 14C-ring-UL p,p'-DDT obtained from the Radiochemical Centre, Amershain, 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. i It ! Results i PCB's. The movement of ,4C radioactivity from Sorghum plants into the water phase i of the model ecosystem is shown in Figure 1. AH 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 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 14C in the spots on the TLC plates. The results for the three PCB's are also expressed in DSW 025249 \ ' .'' ' . ' " r- ' .,l V '> 'i-.*'* . .. 'i /./ t ' - Vv -' : ' ' STLCOPCB40( .: -'::^r V''X-^^y}.%t ^ -^- -' - *'* `1"` w~'. *a<. ^ri.:,_w :..'^:i-TLi...-i-/'v .,i.j.-ii:l .,:-i.ijiia,j -'.^^" ; v^. - i^* . Degradation of Polychlorinated Biphenyls Compared with DDE 153 Table I! 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 tricldorobiphenyl (41.5% Cl) to tetracldorobiphenyl (48.7% Cl) to pcntachiorobipheny] (54.4% Cl). Conversely the B.I. values decreased with increasing degree, of chlorine. This consistent and regular behavior gives added confidence (hat these parameters arc ecologically significant (see Kapoor ct al. 1973) and must be a function of the number of C-H bonds available for hydroxylalion by microsomal oxida tions in (he 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 japonicus. Yoshimura and Yammamoto (1973) have reported the 5-hydroxylated deriva tive as the major and the 3-hydroxylated derivative as the minor excretion product of 2,4,3\4'-tetrach!orobiphcnyl in the rat. Hutzinger et al. (1972) have shown that rat and pigeon could hydroxylate 2,5,2',5'-tetrachiorobiplienyl 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 hydroxylate this tctrachlorobiphenyl. ;w* .*>-" .5J S'*" s ^ :E r* .. t. V ,T 'V. */ -V: J- u' & 'i ? 'v : . y\v. ' /*. day* Fig. 1. Movement of total 14C radioactivity from plants into the water phase of the model ecosystem and uptake by organisms. v i . v. fry osw 025250 *:> . *| r.--: *'v v. .-Vy' A /' . '.7 s . "a v.. -. * ,, * v, * t-rv. *; '; v in ^f. f * V. ' ^ . { : x \.fa-. V V- f "t 1 * ' * M*. * . V' v;-'V * y' *V f 'AfV:'1''-' V ' V ' " V"?f ' t- V ' "'V. '.v :.*; f - -v.' h. 'V ; i.vi .-vPi .* , -4 ; l :z\J. ^ STLCOPCB4009205  i ^ ^ Vi-^ - ^ ^ ^ ^ '1 ^ ' ^ 1 ` ^'.V ^ ^ ^ ' < - :* s*,. v . ^ ' ',';" | ^ '"v* ' ^ '"' ^ . 'if V- . " . . ^ `- ,,^ -. 4. . .^, ^ ` '' V', ',' ' ; *'. :u to wViAiMilt' ilmiil' .1 rJWy.>fr Table I. Distribution of chlorinated biphenyls and their degradation products in the model ecosystem h2o I. 2,5,2'-lrichlorobiphenyl total l4C 0.03845 Unknown I (Rf 0.66) trichlorobiphenyl (Rj- 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 Chlorinated biphenyl equivalents (ppm) Oedogonium (alga) Physa (snail) Culex Gam bu (mosquito) (fish 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 3.205 0.208 1.280 0.159 - 0.9985 0.5590 II. 2,5,2',5-tetrachloro biphenyl total 14C tetrachlorobiphenyl (Rf 0.48") Unknown I (Rf 0.23) Unknown 11 (Rf 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 w- 0.9670 0.7850 15.5685 14.2360 0.0890 -- 0.8545 0.3900 III. 2,5,2'l4',5'-pentachlorobiphenyl total i4C pentachloro- biphenyl (Rf 0.55) Unknown I (Rf 0.46) Unknown II (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 127.694S 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 DSW 02543 SA ' p vv1 . v's >:j.v -..ir .t n ,. .. s' >. . .*>* -* rV-'VSV.< y^s^\- ... -':- V> .. ;?V; *A, - . ': .. ' ;:.. : .-' -v^ '-' ' ' ' STLCOPCB40! Table 11. Ecological magnification (E.M.) and Biodegradability index (BA.) of FCB'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-CI-PCB 16 7,803 7,315 5,79S 815 6,400 0.30 0.17 0.35 0.60 tetra-Cll-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 W:M '.'; ? >'.* ...` ' T ' : f ... .; o 00 at o rv in i rivnj N) TT- f i. -1 ' *. y. , m. "> ; : " 'e\- / ?"f :-'J v7/>. v.1; STLCOPCB4009207 V .1 :V *>'V - " J r ,v. V v,- .;> .;, 156 R. L.. Metcalf el n!. The pentachloiobiphenyl with B.I. values of 0.019 to 0.027 in fish and snail is vei comparable in model ecosystem behavior to DDT, B.I. 0.015 and 0.044 (Kapoor et a 1973) and this suggests (hat the two compounds should behave similarly in the enviroj ment (Risebrough et at. 1968). Properties of the tetrachlorobiphenyl were similar t those of the penlachlorobiphenyl (Figure 2) but the trichlorobiphenyl was much mo> degradable. A prominent degradative product (Rf 0.66) is stored in alga, snail, an mosquito larva in much greater quantities than the parent compound. This compound i less polar (higher Rf) in the hexane solvent than any of the three PCB isomers. As showj in Table 1 it is magnified to very high values, 106,382X in alga and 126.480X iir snail, i stored in lipids, and is highly persistent. Its presence in high amounts in alga and in thr 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 Cl * Cl Cl Cl * Cl Cl * Cl hyd. Fig. 2A. Radioautograin of TLC plate con taining extracts of water and organisms treated with 2,5,2'-trichlorobiphenyI. A (alga), F (fish), M (mosquito larva), S (snail) and STD ('4C-radiolabeled com pound). byd. Fig. 2B. Radioautograin of TLC plate con taining extracts of water and organisms treated with 2,5,2,|S,-tetrachlorobiphenyl. A (alga), F (fish), M (mosquito larva), S (snail) and STD ( 4C-radiolabeled com pound). DSW ^553 .r" <`A STLCOPCB40C Degradation of Polychlorinated Biphenyls Compared with DDE 157 14-day studies. To data wc 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-dichIorofluorcnone intermediates (Plimmet ct al. 1970, Peakall and Lincer 1970, Moilanen and Crosby 1973). Although such rearrangements could logically produce, 4,4'.dicltlorobiphcny), it is difficult to see how trichloro- and telrachlorobiphenyls could be formed as suggested by Maugh (1973). Moreover, Kerner et al. (1972) could detect only ftis-(/>chloiophcnyI)-chloroethylenc (DDMU) after ultraviolet irradiation of DDE. Because of the ecological importance of these possible rearrangements we have reinvesti gated the behavior of DDF. in the model ecosystem (Metcalf et al. 1971) to determine if any PCB-!ike products could be formed under the simulated daylight of the model ecosystem (5000 foot candles) in an environmental chamber. The radioautograph show- V ) t'. fe' .fc . z r '*\ ; .'* *v' * ': ` V; *l.v V- 1 .'V',;-:r<V:Vl > , .'r-yy ; eV;'-> ' jr V. V>.-i ?' '> . .n, \ . ", v\. ;~ A F M STD S H20 HaO hyd. Fig. 2C. Radioautogram of TLC plate con taining extracts of water and organisms healed with 2,4,5,2,,S'-pentachlorobiphenyl. A (alga), P (fish), M (mosquito larva), S (snail) and STD (>`>C-radio' labeled compound). Fig. 2D. Radioaulogram of TECplate con taining extracts of water and organisms treated with DDE. A (alga), I7 (fish), M (mosquito larva), S (snail) and STD (* 4C-radiolabcled compound). v". ; *< < wr 4: r. .! 025254 .X 158 R. L. Metcalf et al. ing the fate of pure DDE is presented in Figure 2. When the extracts of water an organisms were developed on TLC plates with Skellysolve B (hexane fraction) there w; no trace of any 4C labeled compounds with Rf values between 0.05 and 0.47 (DDE) c of any less polar materials with higher Rf values. Under these conditions, as shown ii Figure 2, Irichlorobiphenyl has Rf 0.43, tetrachlorobiplienyl Rf 0.50, and pentachlorobi phenyl Rf 0.53. Detection levels with the techniques used are approximately 0.1 m (e.g., spot at alga origin in DDE, Figure 2) or about 0.00002% of the total MC applied Thus under the model ecosystem conditions there is no evidence of formation of PCI 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 I4C in snail, alga, fish, and mosquito larva. The percent of unextraclable i4C 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'pcntachlorobiphenyl (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 l4C, 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, al though 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 2,5,2'-trichlorobiphenyl in our experiments. How 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 H20 DDE equivalents (ppm) Oedogonium Physa (alga) (snail) Cuiex (mosquito) Cambusia (fish) Total 4C 0.00384 DDE (Rf 0.49s) 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 aTLC with hexane (Skellysolve B, bp 60-68C). DSW 025255 STLCOPCB4009210 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:acelic 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 tire model ecosystem as reservoirs for the bioaccumulation of the micropollutants studied, ihc total amounts of i^CTabeled products recovered from the principal organisms of the mode! ecosystems treated with tri-, tetia-, 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 (Ire various compounds. The highest recoveries of the 14C lost from solution were ob tained from tire organisms with DDE, 65.8%, and pentacldorobiphenyl, 57.2%. With tctrachloroblphcnyl recoveries of 8.7% were still substantial, but with trichlorobiphenyl (recovery 0.45%) the compound was nearly completely degraded and excreted. Table JV, Biomass recovery of chlorinated biphenyls, and DDE from organisms of model ecosystem % Recovery Alga Snail Mosquito .... trichlorobiphenyl * 4C in solution 0.18 0.015 total l4C .0.033 0.0028 (biomass) of 14C lost from solution ---- 0.45 0.0017 0.00032 tetrachlorobiphenyl I4C in solution 3.33 1.04 0.23 total 14C 0.28 0.088 0.019 (biomass) of MClost from solution ---- 8.7 pentachlorobiphenyl ,4C in solution 4.57 19.0 2.32 total t4C 0.74 3.06 0.37 (biomass) of J 4C lost from solution -- -57.2 ,4C in solution 22.4 4.03 total >4C 0.24 0.044 (biomass) of 4Clost from solution ---- 65.8 DDE 2.25 0.055 Fish 0.12 0.021 1.91 0.16 11.8 1.90 20.2 0.22 r i I I' r. % i * DSW 025256 .- .: % . , -. f-f'i f ... ' t ' . ' r,\ s'.. f r ' b? ' 1' | ..''V . -- ^ 'V:. ` "if-.,5 .---v - '( l' ' - ' Y.'.i* M Jt V ' ; l`i ; . ' . -. .. .. ` . . ' STLCOP 160 R. L. Metcalf el al.' Degradation in Salt Marsh Caterpillar. This animal was chosen, after considerabl study, as the dispersing agent for the model ecosystem because it was able to ingest ; large variety of organic compounds without apparent injury (Metcalf et a!. 1973). Tlv effects of passage of the PCB isomers through the insect are of interest as representin; the first stage in the biodegradation of these compounds. Figure 3 shows radio autographs of TLC plates of extracts of feces and body homogenates hom larvae feedin; on about 30 /rg of 14C PCB incorporated in a synthetic diet. Figure 3 and the quantitative tri-CI tetrs-CI perna Cl Fig. 3. Radioautogram of TLC plate containing extracts of bodies and feces of salt marsh caterpillar larvae fed ,4CTabeled 2,5,2'-tri~, 2,5,2,,5'-tetra-, and 2,4,5,2',5 -pentachlorobiphenyls. B (body homogenate), and F (fecal excreta). DSW 025257 . i J . *. t . i'4 .1 t r v, . ... - * -* '*'* STLCOPCB4009212 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 trichlorobiphenyl over the tetrachlorobiplicnyl and pentachlorobiphcnyl. With tire tricldoro-compound the caterpillar feces con tained 91% of the recovered 14C, with the remainder in the body homogenate, while with the (ctrachloro- and pentachlorobiphenyls, the feces contained 21% and 24% of the radioactivity. Tire unknown (Rr 0.0S) found in feces after trichlorobiphenyl is probably the principal hydroxylaled degradation product leading to the very large amount of polar radioactivity. Whereas only tow levels of trichlorobiphenyl 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 caterpillar3 Body Feces A. 2,5,2'-trichlorobiphenyl total 14C(%) Unknown l (Rf 0.53) trichlorobiphenyl {Rf 0.43) Unknown 11 (Rf 0.31) Unknown 111 (Rf 0.13) Unknown IV (Rf 0.05) Unknown V (Rf 0.02) Polar (Rf 0.0) B. 2,5I2,,5'-tctrachlorobiphenyl total 14C(%) tetrachlorobiphenyl (Rf 0.50>) Unknown I (Rf 0.41) Unknown 11 (Rf 0.05) Unknown MI (Rf 0.03) Polar (Rf 0.0) C. 2,5,2',4,,5'-pentachlorobiphenyl total 14C(%) penlachlorobiphenyl (Rf 0.53s) Unknown I (Rf 0.46) Unknown II (Rf 0.39) Unknown 111 (Rf 0.03) Polar (Rf 0.0) D. 2,2-6rs-(/nchloiophenyl)-l,l-dichloroethylene (DDE) total iC(%) DDE (Rf 0.49*) Polar (Rf 0.0) aTLC with hexane (Skcllysolve B, bp 60-68C). 8.66 0.64 S.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 i vwr v V* .v ; vw\ c % A -J * ' {; r Sf. DSW 025258 STLCOPCB4009213 162 R. L Metcalf cl al. ; DDE passed through the salt marsh caterpillar largely unchanged with 81% of the : total radioactivity recovered retained in tire body homogenate and 19% in the fecal ! excreta (Table V). 1 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 1 important factors, their high lipid solubility and low water solubility, i.e.. a large lipid/ i water partition coefficient; and their resistance to degradation by enzymatic processes, I especially the multifunction oxidase enzymes (Metcalf et al. 1973). Hameiink cr al. | (1971) have suggested that the water insolubility of highly lipid-soluble compounds pro- j vides the driving force in producing lipid storage, through a series of simple partitionings j 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/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 i 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, i The regression equation for log water solubility vs log E.M. (Figure 4) was: . y - 4.4806 - 0.4732 X : n = 9, i~ ^0.9677 Fig. 4. Plot of log E.M. (ecological magnification) for fish w. log water solubility (ppb). ' '.`V ,6i V,, V*/ V>. ,M S' j.-- OSW 025259 STLCOPCB4009214 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. V"'/- '*/. {< y*.`A -v < ili 'Vu;*:- % !. . t., A Log partition coefficient rip,. 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 (lie 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 tire Bureau of Veterinary Medicine, Food and Drug Administration, Contract FDA 72-116. /: . .\j. STLCOPCB4009215 164 R. L. Metcalf el a!. 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