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TOXICOLOGY AND APPLIED PHARMACOLOGY 37, 217-228 (1976) Elimination of Chlorinated Dibenzofurans Associated with Polychlorinated Biphenyls Fed to Mallards (Anas pJatyr/iyncftos) R. J. Norstrom,1 R. W. Rjsebrough, and D. J, Cartwright Toxic Chemicals Division, Canadian Wildlife Service, Department ofthe Environment, Ottawa, Canada KlA 0H3; Bodega Marine Laboratory, University of California, Bodega Bay, California 94923; and Department ofBiology, York University, Downsview, Ontario, Canada Received November 23,1975; accepted February 9,1976 Elimination of Chlorinated Dibenzofurans Associated with Poly chlorinated Biphenyls Fed to Mallards {Anas platyrhynchos). Norstmom, R. J., Risemouoh, R. W., and CaRTWRIOHT, D. J. (1976). Toxicol. Appi. Pharmocoi. 37,217-228. A method which allows chlorinated dibenzofurans (CDFs) to be extracted from lipid and separated from interfering poly chlorinated biphenyls (PCBs) was tested. Greater than 90% recovery of tetrs- to hexa-CDFs was found. Starting with 40 g of lipid, the detection limit for individual CDFs in lipid was ofthe order of 0.01 /jg/kg, Lipid from mallards which had been fed Aroclor 1254 for approximately I year at levels from S to 100 mg/kg in the diet was found to contain 3750 mg/kg of PCB. The minimum concentration ofindividual CDFs (nine tetra- to hexa-CDFs) potentially in the lipid from this PCB concentration was in the order of several tenths jig/kg. It was concluded (hat less than 3 % of the dosed CDFs were accumulated by the mallards, since CDFs could not be detected by a comparison of lipid to Aroclor 1254 extracts containing the same amount of PCBs. It appears unlikely that CDFs are sufficiently persistent in avian species to enable their detection in environmental samples. The chlorinated dibenzofurans (CDFs) are structurally similar to the chlorinated dibenzo-p-dioxins (CDDs), some of which are both highly toxic and teratogenic (Schwetzefo/., 1973; Verrett, 1971). The effectiveness ofseveral tetra-and penta-CDFs, particularly 2,3,7,8-tetra-CDF, in inducing aryl hydrocarbon hydroxylase activity has been found to be nearly as high as that of 2,3,7,8-tetra-CDD (A. Poland and A. S. Kende, personal communication), the latter being the most toxic of the CDDs. The potency of aryl hydrocarbon hydroxylase induction by CDDs has been shown to be strongly correlated with toxicity (Poland and Golver, 1973). A dietary level of 5 pg/kg of 2,3,7,8-tetra CDF was found to be highly toxic to chicks (Goldstein et a/., 1974). Embryotoxicity of the polychlorinated biphenyls (PCBs) Clophen A-60 and Phenoclor DP-6 has been attributed to CDFs present as trace contaminants in the commercial preparations (Vos and Koeman, 1970; Vos et a/., 1970). Subsequently, tetra-, penla-, and hexa-CDFs were detected in the American preparations of PCB, 1 Address correspondence to R. J. Norstrom, Toxic Chemicals Division, Canadian Wildlife Service, Ottawa, Ontario, Canada K1A 0H3. Copyright C IW toy Aeedemk Prw. Ine. AN rl|M ofreprodiictton in any form reserved. Primed I* Greet Ihiliie 217 moms 08 73*0 218 NORSTROM, RISEBROUGH AND CARTWRIGHT Aroclor 1248,1234, and 1260; concentrations orthe individual CDFs were in the order of 0.1 jig/kg of the PCB (Bowes et ai, 1973). Therefore, CDFs are possible causes of embryonic mortality and birth defects observed in PCB-feedingexperiments(Tumasonis et a/., 1973), and in PCB-contaminated populations of Common Terns (Sterna hirundo) in Long Island Sound (Hays and Risebrough, 1972) or HerringGults(Larar orgm/a/itf) in Lake Ontario (Gilbertson and Hale, 1974). Although little is known of their environmental persistence or accumulation in food webs, substantial amounts of CDFs have entered the global environment associated with PCBs as well as with chlorinated phenols (Buser et ai, 1975). Attempts to detect CDFs in eggs of Common Terns (Sterna hirundo) and Ospreys (Pandion haliaetua) from Long Island Sound, in eggs of Herring Gulls from Lake Ontario (R. W. Risebrough and G. W. Bowes, unpublished results; Bowes et ai, 1973), and in several species of birds and fish from the Bay of Fundy region (Zitko, 1972) have been unsuccessful. In some cases, amounts of material used for lipid extraction, cleanup, and subsequent analysis may have been too small. Before starting on a more exhaustive search for residues in birds whose lack of reproductive success may be attributable to CDFs, it was considered important to establish a method for quantitative recovery, and to obtain information on the persistence of CDFs in avian species. A PCB-feeding experiment of mallards (Anas platyrhynchos) carried out in 197!and 1972 showed both embryonic mortality and deformities among ducklings (D. Cartwright, unpublished results). Subsequently the Aroclor 1254 used in this experiment was examined for its CDF content, and the concentrations of tetra-, penta-, and hexaCDFs were determined [preparation Aroclor 1254 (1970) of Bowes et ai., 1975a]. Total CDF concentration was 1.5 mg/kg of the PCB used. A high PCB concentration in the mallards at the end of the experiment and the ample amount of available material afforded an opportunity to determine the relative persistence of CDFs to PCBs in duck tissues during the feeding experiment. METHODS PCB Feeding Experiment Aroclor 1254s was dissolved in corn oil and stirred into duck feed with a Hobart feed blender. Three groups of 22 birds, 11 females and 11 males, were fed diets containing 5, 50 and 100 mg/kg of Aroclor 1254 starting January 1, 1971. Progeny of these birds hatched in the spring of 1971 were fed on the same diet as their parents until June 22, 1972, when they were killed. The average dosage period of the progeny was 296 days. A total of 23 progeny, about four males and four females from each of the dosage groups, was used for the current study. Beaks, long wing feathers, and feet were removed and discarded, and the remainder was thoroughly homogenized by three passes through a Hobart food chopper. After mixing and freeze drying, about 10 % of the sample was placed in a preextracted paper thimble in a large Soxhlet apparatus and extracted with 5 liters of hexane/acetone azeotrope for 48 hr. The bulk of the solvent was removed in a large evaporating dish on a warm hot plate with successive additions of the extract to prevent oxidation of lipid, and the final solvent removed under a nitrogen stream, leaving 740 g of lipid. * Canada Colours, Ltd., Toronto, Canada; purchased in 1970. MQNS 087349 CHLORINATED DIBENZOFURANS IN MALLARDS 219 Two 0.5-g aliquots of the lipid were cleaned up for PCB analysis on a 2% waterdeactivated Florisil column (McLeod and Ritcey, 1973) using 300 ml of hexane as the eluant. All analyses were performed on a Hewlett-Packard 5700 A gas chromatograph equipped with a linear Ni-63 detector and a 6-ft x 2-mm i.d. glass column at 190C packed with 3% SP-2100 on Supelcoport 100/120 mesh.3 Other conditions were: injection port at 250C, detector at 300C, and flow rate at 30 ml/min of 10 % methane in argon. Chromatograms of the Aroclor 1254 standard and the lipid extract are compared in Fig. 1. Using the peak with retention time approximately 10 min as reference, the concentration ofAroclor 1254in the lipid was calculated to be 3750 mg/kg. a io is to is TIMS MMI Fto. I. Relative abundance of PCBs in Aroclor 1254 compared to those in mallard lipid after 296 days* administration of Aroclor 1254. The chromatograms have been normalized to the peak with retention time of 10 min. Separation of CDFsfrom Lipids and PCBs The method for separation of CDFs and PCBs from lipids (procedure 1,Table l)was adapted from thecolumn partitioning method ofPorter and Burke (1973). The necessity of using large volumes of lipid ruled out adsorption column cleanup. The FlorisilVlipid column was prepared according to Porter and Burke (1973), but the eluting solvent was changed to 3 % water/acetonitrile. The acetonitrile was shaken with 100 ml of hexane, then 50 ml of saturated sodium sulfate, 800 ml of water, and 15 ml of methylene chloride were added. After shaking again, the aqueous layer was discarded and the hexane layer was washed twice with 100 ml ofwater. The hexane layer was filtered through anhydrous sodium sulfate, evaporated to dryness in a rotary evaporator, and the residue was taken up in 5 ml of hexane. Previous experience in our laboratory had shown these modifi cations to give essentially 100% recovery of organochlorines such as Mirex which are poorly recovered by the original method, without significantly increasing the amount of co-eluting lipid. The separation of PCBs from CDFs was the same as that of Bowes et al. (1975a). The bulk of the PCBs was removed on a column of 180 g of Florisil (deactivated with 2% water), as outlined in procedure 2, Table I. Up to 2 g of PCBs may be placed on the column. * Supelco, Inc., Beltefbnte, Pa. * Florisil PR grade; Floridin Corp., Pittsburgh, Pa. MOMS 087350 NORSTROM, RISE0ROUGH AN D CARTW RIG HT TABLE i Column Chromatoorafhy Procedures Used for the Separation of CDFs from PCBs and Lipids' Procedure No. 1 2 3 Column type Partition* Florisil* Alumina4 Eluant 5 % water/acciomiriic hexane 5 % diethyl ether/hexane 5 % diethyl ether/hexane 25 % diethyl ether/hexane 25 % diethyl ether/hexane acetone 1 % methyl chloride/hexane 20% methylene chloride/ hexane 50 % methylene chloride/ hexane Eluant volume 200 1200 400 400 400 400 500 10 10 10 Fraction no. __ 1 2 3 4 5 --_6_ Content of fraction Lipid, biogenic hydrocarbons. PCB,, PCN, and CDF, PCBs, PCN* PCBs, PCNs, dt- and tri-CDFs PCBs, PCNs, tens- and penta- CDFs PCBs, PCNs, tetra-, penta-, and hexa-CDFs PCBs, PCNs, hexa-CDFs, lipid, and biogenic hydrocarbons lipid, biogenic hydrocarbons PCBs, PCNs tetra- to hexa-CDFs, some PCNs, lipid and hydrocarbons lipid, biogenic hydrocarbons * CDF = chlorinated dibenzofuran; PCB * polychlorinated biphenyl; PCN polychlorinated naphthalene. * Porter and Burke (1973). See text for modifications. For mallard lipid, five partition column eluates, concentrated to 10 ml, were combined for procedure 2. ' Vos aal. (1970); Bowes etai. (1975a). Fractions I and 2 contained the majority of the PCBs, and were discarded. Fractions 3,4, and 5, which were highly enriched in CDFs and PCNs, were evaporated just to dryness and taken up in 1 ml of hexane for procedure 1. Fraction 6 did not contain any CDFs. * Porter and Burke (1971). Fractions 3, 4, and 5 may be passed through procedure 3 either separately or combined. The first duate was discarded. The second duate was evaporated to dryness, then taken up in 1 ml of hexane and tested by GC for the presence of PCBs. The second eluatt was passed through procedure 3 up to two more times. The third eiuate potentially contained higher chlorinated CDFs, but no CDF present in PCB mixtures has been found ia this eiuate. MQNS 087351 CHLORINATED DIBENZOFURANS IN MALLARDS TABLE 2 Recovery o Tju- to Hexa-CDFs from the Cleanup and PCB Separation Procedures* Recovery teat no. Procedure no. from Table 1 2,3,8-tri-CDF 3,4,6,7-tetraCDF Percent Recovery of: 1,2^,7,8-penttCDF 1,2,3,6,7,8-hexa* CDF 2.3,4,6,7,8-hexaCDF 1 2 92 2 2 and 3 87 3 1,2. and 3 82 95 97 94 95 95 93 40* 39 36 94 94' - * The spiking levels and test solutions are described in the text. All recoveries are the mean oftwo results. The results were within 2 percentage units from the mean in all cases. * A large excess of acetone eluant did not recover any further amount. `Therecovery in the alumina procedure (No. 3. Table 1) was 39% in the 20% methylene chloride/hexane fraction. An additional 55 % appeared in the 50% methylene chloride/hexane fraction. K> H0N 08735,! 232 NORSTROM, RISEBROUGH AND CARTWRIGHT Further separation to remove last traces of PCBs was accomplished by passing fractions 3, 4, and 5 from the Florisil column through an alumina3 microcolumn, u outlined in procedure 3, Table 1. Each of the three 20% methylene chloride/hexane eluates was passed two more times through procedure 3. In order to have as direct a comparison as possible between COFs in Aroclor 1234 fed to mallards and the amount present in the lipid, a solution ofAroclor 1254 was made in corn oil so that the PCB concentration was the same as that in the mallard lipid (3750 mg/kg). A series of five 8-g aliquots of both the corn oil solution and the mallard lipid were then carried through procedure 1 (Table 1) and combined for separation of the PCBs and CDFs by procedures 2 and 3, for a total of 40 g of lipid and 150 mg of PCB per sample. The series was done in duplicate. The final volume was 1 ml for each of the three final fractions used for GC analysis. Recovery Experiments The recovery of CDFs was studied in three tests employing spikes of authentic CDF standards. A tri-, tetr*-, penta- and two hexa-CDFs, as indicated in Table 2, were chosen because their retention times on the SP-2100 column employed for GC analysis did not overlap those of any CDFs present in Aroclor 1254 (Bowes et a/., 1975b). Aroclor 1254 was spiked at the 0.1-mg/kg level with the first four authentic CDFs for recovery tests 2 and 3. The solutions for each of the recovery tests were made up as follows: test 1, approximately 15 mg of each of the five authentic CDFs dissolved in 10 ml of hexane; test 2, 2 g of spiked Aroclor 1254 dissolved in 100 ml of hexane; and test 3,150 mg of spiked Aroclor 1254 dissolved in A g of com oil. RESULTS Table 2 indicates the results of the recovery tests. With the exception of 1,2,3,6,7,8hexa-CDF, the recovery of all CDFs was generally greater than 90%. Neither the absolute amount of CDF present, nor the presence of PCBs and lipid appeared to affect the recoveries. The tri-CDF was partially lost in the alumina chromatography step. The methods outlined in Table 1 can therefore be recommended for CDFs with four to six chlorine atoms per molecule. It is not known whether hepta- and octa-CDFx would be recovered by the methods. Complete recovery of 2,3,4,6,7,8-hexa-CDF from the alumina column required a 50% methylene chloride/hexane eluant The low recovery of 1.2,3,6,7,8-hexa-CDF could be ascribed to partial decomposition during storage as a solution in hexane. GC analysis of the standard showed the parent and a decomposition peak at longer retention time. The second peak was not recovered in any of the tests, indicating that it was a polar compound. Since the parent CDF was recovered in fractions 4 and 5, Table 1, but no more could be eluted with acetone in fraction 6, it is probable that during decomposition a compound formed which could react in the GC inlet to reform the parent CDF, but could not be eluted from Florisil. The pattern of PCB accumulation by the mallards at the end of the 296-day dosing period is shown in Fig. I. AH peaks with retention time less than approximately 6 min were significantly reduced relative to the later peaks. Peaks with retention time greater than approximately 10 min remained essentially unchanged in height relative to one * Cat. No. AS40: Fisher Scientific, Fair Lawn, N.J. M0NS 087353 CHLORINATED DIBENZOFURANS IN MALLARDS 223 another when the malltrd extract was compared to the Aroclor 1254 standard, as was found for White Carneau pigeons (deFreitas and Norstrom, 1974). This is strong indi cation that the later PCBs were not metabolized to any extent by the mallards. Elimination of unmetabolized PCB did, however, occur in females, since egg produc tion is an important route of excretion of unmetabolized PCBs from female birds (Dahlgren et at., 1972). In the present study, the majority of females were producing eggs during the 3-month period prior to sacrifice. As a result, the PCB concentration in the fat ofindividual dosage groups, which ranged from a low of 300 mg/kg for 5 mg/kgfed females to 9988 mg/kg for 100 mg/kg-fed males, was two to three times higher for males than females in each dosage group (D. Cartwright, unpublished results). The PCB concentration in the lipid of the composite whole body sample used for CDF analysts therefore gave the minimum amount of CDFs potentially in the lipid, that is, assuming that no metabolism or excretion of PCBs or CDFs had occurred. Using values given by Bowes et at. (1975a) for the CDF content of Aroclor 1254 {1970), and 3750 mg/kg of Aroclor 1254 in lipid, the minimum potential concentrations in the lipid were approximately 0.8 fig/kg of tetra-CDFs, 1.5 pg/kg of penta-CDFs, and 0.9 fig/kg of hexa-CDFs. Figure 2 compares the CDF content of 150 mg of Aroclor 1254 standard to the CDF content of40 g ofmallard lipid. The lipid also contained 150 mg of Aroclor 1254, based on the PCB reference peak with retention time 10min(Fig. 1). For the individual CDFs TABLE 3 Identity or the CDFs and PCNs Present in Aroclor 1254 Peak designation* Compound type No. of chlorines Relative retention lime* Reference* A CDF* 4 1.58 a B PCN 6 1.72 a C PCB 5 1.90 a D PCN 6 2.00 a E CDF 5 2.40 b F CDF 5 2.54 b G CDF 5 2.77 b H CDF* 5 2.95 a I PCN 7 3.44 a J CDF 6 4.n c K CDF 6 4.25 c L CDF 6 4.68 b M CDF 6 4.98 b N PCN 8 5.68 c * At shown on Fl(. 2. * Relative to diddrin on a ML, 3 % SP-2100 (OV-1) column. * a, Bowes tt of. (1973a); b, Bowes et of. (1973); c, G. W. Bowes, personal communication. 4 Positional Isomer identified as 2,3,7,S-tetrachlorodibcnzofuran. * Positional isomer identified as 2,3,4,7,8-pentechlorodibcnzofuran. MUNS 087354 224 NORSTKOM, RISGBROUGH AND CARTWRIGHT in Aroclor 1254, the peak height reproducibility between duplicates was within 10%. The lettered peaks and their retention times relative to dieldrin are listed in Table 3. Only two of the nine CDFt have been structurally identified (Bowes et al., 1975b). With minor exceptions, there were no detectable peaks in the mallard lipid extract that matched & CDF present in Aroclor 1254. Based on a 2-mm peak height, less than TIMItMW) Fk>. 2. Relative abundance of CDFs in Aroclor 1254 (lower chromatograms) compared to those in mallard lipid (upper chromatograms) after 296 days' oral administration of Aroclor 1254. Upper panel (A) is Fraction 3, Table l; middle panel (B) is Fraction 4, Table 1; panel (C) is Fraction 3, Table I. The amount of Aroclor 1254 represented is the seme for all chromatograms, based on the peek with retention time lO-mio, Fig. I. MOMS 087355 CHLORINATED DIBENZOPURANS IN MALLARDS 225 Flo. 2 eontbnt*d 3 % of the minimum potential concentration of CDFs was estimated to be present.The actual concentration may have been much lower. The detection limit for individual CDFs was estimated to be in the order of 0.01 pg/kg starting with a 40-g lipid sample. The large peak in the mallard extract with a similar retention time to peak A (Fig. 2A) was shown not be 2,3,7,8-tetra-CDF by means ofdiffering retention times on a 5-0 3 % OV-1/5% OV-210, 0.5-flt 3% OV-I/6% OV-225 column. The efficiency of PCB and polychlorinated naphthalene (PCN) separation from CDFs in mallard fraction 3 (Fig. 2A) was not as good as, and more variable than that ofpure Aroclor 1254, probably due to the presence of biogenic hydrocarbon or lipid materials. The heptachloronaphthalene, peak I, derived from Aroclor 1254 was present in large quantities in the mallard lipid (Fig. 2B), indicating that it was not easily metabolized or excreted. The negative peaks in the chromatogram of mallard fraction 5 (Fig. 2C) were shown to be due to hydrocarbons when Florisil cleanup and treatment with concentrated sulfuric acid did not remove them. OC analysis using a flame ionization detector showed a continuous series of peaks with retention times from 5 min to 2 hr. DISCUSSION Little is known about the environmental persistence and bioaccumulation potential of CDFs. They are chemically stable (e.g., towards strong acids and bases) like many of the more persistent organochlorines, but also more photochemically labile than PCBs (Hutanger sf ai, 1973). There is some evidence that Atlantic salmon (Salmo solar) accumulated dt-, tri-, and tetri-CDFs from food to increasingly higher levels as the number ofchlorines/molecule increased (ZitkoeM/., 1973). Explanations forthe increase included easier metabolism, faster excretion and decreased efficiency of uptake from the G1 tract of the tower chlorinated CDFs. The accumulated concentrations of alt CDFs were very low. Curley et at. (1975) produced tentative mass spectral evidence that a MONS 087356 226 NORSTROM, RISEBROUGH AND CARTWRIGHT tetra-CDP was eliminated in the urine of rats fed Arodor 1254. The presence of 2,3,7,8tetra-CDF in Aroclor 1254 has been confirmed (Bowes et a/., (975b). The ability to detect CDFs in urine suggests that they are more rapidly eliminated from the rat than PCBs, since the total tetra-CDF intake of all rats throughout the study was approxi mately 2.4 /ig," and the urine sample represented only a small time period in the PCBingestcon experiments. Studies with the chemically similar CDDs may be indicative of CDF bioaccumu lation potential. Microbial metabolism and model ecosystem studies with 2,3,7,8-tetraCDD (TCDD) indicated that it was more stable towards metabolic breakdown than most organochJorine compounds (Matsumura and Benezet, 1973; Isensee and Jones, 1975). However, unlike DDE and the more highly chlorinated PCBs, which are also relatively resistant to metabolism, TCDD appeared to be less efficiently absorbed from the GI tract, and was cleared from organisms more rapidly as the unchanged molecule (Vinopal and Casida, 1973; Piper et al.t 1973). The evidence, therefore, seems to point to a faster elimination of CDFs than ofPCBs, which is strongly reinforced for birds by the present study which has shown that mallards eliminated >97% of all CDFs associated with Aroclor 1254 in the long-term feeding experiment. The PCB concentrations reached were similar to those found in the most highly contaminated wild birds, such as Herring Gulls in Lake Ontario (Gilbertson, 1974; Frank et a/., 1975). A large body burden of PCBs may contribute to more rapid clearance of CDFs by inducing a higher level of hydroxylase activity. Further attempts to find CDF residues in the environment, even in birds with excep tionally high PCB concentrations, appear destined to fail. The practical difficulties of environmental CDF analysis can be seen from the present study. To achieve the CDF detection limit of0.01 pg/kg in lipid, approximately 500 g wet weight tissue, containing a potential CDF concentration of 0.8 ng/kg (ppt), was required for each analysis. The use of mass fragmentography may eliminate time-consuming cleanup steps (Buser, 1975), but is unlikely to give much better detection limits. The contribution of chlori nated phenols to environmental contamination by CDFs may be as high as that of PCBs (Firestone etal., 1972), but given the apparent lack of CDF bioaccumulation, this contribution is also unlikely to result in measurable residues at the top of a food web. ACKNOWLEDGMENTS The authors gratefully acknowledge the assistance of M. J. Mulvihill in the development of proceduresand performance of the analysis. G. W. Bowes provided mess spectral information ad helped to set up the study. The authentic CDF standards were provided by A. S. Kende. The PCB feeding experiments were financially supported by the Canadian Wildlife Service. REFERENCES Bowss, G. W.. Mulvihill, M. J., Simonbit, B. R. T., Burlingame, A. L., and Risemouoh, R. W. (1975a). Identification of chlorinated dibenzofurans in American polychlorinated biphenyls. Nature (Lontbm) 256,309-307. Bowes, Cl. W,, Mulvihill, J. J., DbCamp, M. R., ano Kende, A. S. (1973b). Gss chromato graphic characteristics ofauthentic chlorinated dibenzofurans; identification of two isomers in American and Japanese polychlorinated biphenyls. J. Agr. Food Chem. 23, 1222-1223.* * Three granu total Aroclor consumption times 0.8 mg/kg tetra-CDFs (Bowes #/ at., 1975a). HONS 087357 CHLORINATED DIBENZOFURANS IN MALLARDS 227 Bowes. G. W., SlMONEIT, B. R., Burlinoamb, A. L., oe Lapps, B. W., and Riserrough, R. W. (1973). The search for chlorinated dibenzofurans and chlorinated dibenzociioxms in wildlife populations showing elevated levels of embryonic death. Environ. Health Perspect No. 5,191-198. Buses, H. R. (1973). Analysis of polychlorinated dibenzo-p-dioxjns and dibenzofcrans in chlorinated phenols by mass fragmentography. J. Chromatog. 107,295-310. Curley, A.,Boast,V W.,Jennings,R. W.,Villaneuva,E. C.,andKimbrough,R.D.(!975). Evidence of tetrachlorodibenzoAiran (TCDF) in Arodor 1254, and in the urine of rats following dietary exposure to Arodor 1254. Soli. Environ. Contam. Toxicol. 14, 133-158. Dahloren, R. B., Linder, R. L. and Carlson, C. W. (1972). Polychlorinated biphenyls: Their effects on penned pheasants. Environ. Health Ferspect. No. I, 89-101. deFrutas, A. S. and Norstrom, R. J. (1974). Turnover and metabolism of polychlorinated biphenyls in relation to their chemical structure and the movement of lipids in the pigeon. Canad. J. Physiol. 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Pollutant concentrations in abnormal young terns from Long Island Sound. The Auk 89,19-35. Hutzinoir, O., Safe, S., Wbntzbll, B. R., and Zitko, V. (1973). Photochemical degradation of di- and octochlorodibcnzofljran. Environ. Health Perspect. No. 5,267-271. IstNsat, A. R., and Jones, G. E. (197$). Distribution of 2,3,7,8-tetrachlorodibenzo-p*dioxin (TCDD) in aquatic model ecosystem. Environ. Sci. Technoi. 9,668-672. Matsumura, F., and Benezbt, H. 3. (1973). Studies on the bioaccumulation and microbial degradation of 2,3,7,8*tetrachloro-p--dioxin. Environ. Health Persped. No. 5,253-238. McLeod, H-A., and RiTCEY, W. R. (1973). Analytical Methods for Pesticide Residues in Foods, Rev. Ed. 1973, Section 7. Health Protection Brandt, Health and Welfare Canada. Ottawa. Pirn, W. N., Roes, J. Q., and Genrino, P. J. (1973). Excretion and tissue distribution of 2,3,7,S^rachlorodibenzo-p'dioxin in the rat. Environ. Health Persped. Na. 5,241-244. Poland, A., and Glovcr, E. (1973). Studies on the mechanism of toxicity of the chlorinated dibenxorydwwdne. Environ. Health Ferspect. No. 5, 245-252. Foutbr, M L., and Burke, J. A. (1971). Separation of three chforodibenzo-p-dioxins from some polychlorinated biphenyls by chromatography on an aluminum oxide column. J. Au. Offic. Amt. Chem. 54.1426-1428. Porter, M. L., and Burkx, J. A. (1973). An isolation and cleanup procedure for low levels of organochlorine pesticide residues in fets and oils. J. Ass. Offic. Anal Chem. 56, 733-738. Schwvtz. B. A.. Norris, J. M , Sparschu, O. L., Rows, V. K., Gbmrino. P. J., Emerson, J. t., and UkNBio, C. G. (1973). Toxicology of chlorinated dtbenzo-p-dioxins. Environ. Health Ferspect. No. 5,87-100. Tumasonh, C. F., Bush, B., and Barb*. F. D. (1973). PCB levels in egg yolks associated with embryonic mortality and deformity of hatched chicks. Arch. Environ. Contam. Toxicol 1, 312-324. VBRRETT, J. (1971). Report on 2,4,5,-T. (Executive Office of the President, Science Advisory Committee, Office of Science and Technology, March.) MONS 087356 22* NORSTROM, RISEBROUOH AMO CARTWRIGHT Vinopal., J. II., andCmida, J. E. (1973). Metabolic stability of 2,3,7,8-tetrachlorodibenzo-p- dioxin in mammalian liver microsomal systems and in living mica. Arch. Environ. Contain. Toxicol. 2, 122-132. Vos, I. G., and Kocman, J. H. (1970). Comparative toxicologic study with polychlorinated bipheoyla in chicken* with special retoenee to porphyria, edema formation, liver necrosis, and tissue residues. Toxicol. Appi. Pharmacol 17,656-668. Vos, J. G., Kobman, J. H., Van Den Maas, H. L., Tin Noavan dbBrauw, M. C, ano oa Vos, R. H. (1970). Identification and toxicological evaluation of chlorinated dibenzoAtna and chlorinated naphthafeoe In two commercial polychlorinated biphenyl*. Fd. Cosmot. Toxicol. g, 625-633. Zvnto, V. (1972). Absence of chlorinated dibenzodioxina and dlbenxorurans from aquatic animals. Bull. Environ. Contam. Toxicol. 7,105-110. Zrnco, V., Wildish, D. J., Hutzimobr, O., and Choi, 9. M. JC (1973). Acute and chronic oral toxfdty of chlorinated dibenzofurans to salmonid Ashea. Environ. Health Perspcet. No. S, 187-190. MQNS 087359 can 1 > icpresented hv .1 m.ip composed of eigenvectors .! .mt K .is follows: m.ip ,i s 7h (ciceilvev tor !l '- 5 I ' (eigenvector ** (Jl white tin1 nmni iK.it cnelhc units .ire l.iken from eviit.ilum Mi smidaiis, die tree growth anoni.dv pattern curespond ing to the war I'nHnwine .i high percentage "I .ilti.ii.nrc caught notlh ot S.m Iratkiscii can he repesvnted .is: map />-X xft (eigenvector 4 I - (i I 7 (eigenvcwlor *>) 1-11.5*1 eigenvector I0| cJ> these maps .tie picsonicd m tig. 4. live nng-vvidlh il.ita wcic niosih horn lives sited m and localities, so 1h.il a wide ring would generally he .issiuiated with anomalously cool, cloudy weather ami above normal precipitation whereas a narrow ring would wflcct warm. sunny and dry condition* Helnw normal tree growth iu the Pacific North-west ll ig 4) is indicative of dr* conditions associated with below noimal cyclonic .uliviiv during the lisbing season. Sunny and mild weather would favour .illiniorv fishing in adincvni waters, .is would above normal insolation regard less of weather. I he resulting excess of stored heat in the ocean would he given up through evaporation during the followiltp autumn ami winter ami lead to increased cyclonic activity and precipitation .dong live const north of San I raiKisco. I hese conditions would lead to increased tree growth during the following growing season (l-iu. l) Autumn and wmtvr climatic anomaly features, com bined with spring climate and fie year-to-year autocorrela tion of tree-ring widths, prt*duec the other ring-width anomnly features in f ig. 4 lor the following growing season. Narrow ring widths south ol S.m I r.mciseo, for example, imply below normal precipitation-an expected fcaluio since winter precipitation in (lie I'acilic North-west is negtilively correlated with winter precipitation in southern (dlir*mi;i* the reconstructed values of alhacore catch distribution data (big. ,t| and inferred I'opidation distribution also siein to exhibit long term changes over intervals of 100 yr or mote, which suggest the jmssihiity tfv.il long icrin tlucUia(ions in (he ocean atmosphere system nvay Ivy involved. I he success of the calibration of tree rings with alhacore ciihb indicates the posxihiliiv of relating tree-nog variaItotis to .my t\pe of biological variations which are affected by large scale climatic ItintiMiions Such relationships may Ih.1 viii.iniitied and used to reeonviiuct ohjcetively other climatically-caused hiotic \aii.itrons ill the past. N I*. (j.AMK ,\uih>nni Otvonic anil .1 imm/i/.rrir Aihninntratnm, \aii,'itul Miami' i'i\hfrn \ XVn/tr, Sonr/invvr f-ivfn-riev Vvnu-r. I.tl lolla. Calilnmia 0-70*7 * l\ J / afhiiainrv <( /V.-e Mint; Hc*< urt h. II. t I'niwrutv t*( .trr.ouu. I in k-m. tn*<mu .V^7?/ Hi vsiNfj I hii is Oafs may grow better in wsifer depleted in oxygen 18 and deiKeritim XX growing o.us .11 iltdvreiii temper,nines 111 a.iki .a dilleivul ''() .mil deutermui < I >) abmidaiu.es. we noiiccd ili.i* 0.1 Is grow 11 in A iilan.'a w a let' in w Mk'i is depleted nr ! 1 .mil I > by 4` ,iml 400 ..relative 10 si.md.n .1 mem m can w.xtei (S.MOW used as .1 s omp.11 a 11 v e ickiviKc 111 hvdi'00111 md oxygen isotope studies), showed imti.d glow ill I J weeks soonci than disl oats giowu m w.tu'i couiamme ,'teak't ' () .md I) concentrations. I lie oats seemed to glow he iter m w.i'ci which was most depleted m the viable im Mopes 1 hn .uetuuM tin- erow t li permit. The lints were grown tiom 1 lie same hatch ol seeds in inn sealed glass-coveted glass mis i.ippiocimaiely to l Ivwiitv live oat seeds wen- added lo eav.li |.u, containing (he >.m<e amount of vcitniuilite and 'OO ml vv.iiei In wIikIi s 11 g Kaput ( iro, a commercial let tiliser. havl been .ulded, < >nc uir contained melted glacial ice 110111 Hie An lap cl ic vv 11 h is.>1 ope coim mm ,.i i,.ns ot 40 ., ti'-O 1SVIOVV1 and 400 ahiSMOU) li.codm Uir contained distilled ocean water w nil in. .d'O tXMt i\\ 1 and -17 til) (SM( l\Vi I ha h 1,1 is vv ere placed in the v li.iml'i r .it the same time l he experiment was repeated three 1 lines w n b new ni.nci i.tls. once ihcgrowthchainbcrwusUMiMi.iinevI helween 1.7 md 1 ' ( . once between 74 ami 'ft t> t ; and once the temper.mire Ihictoalcd Ivctween I 7 and 2h ft ( . l ach 1 rmc 1 tie 0.1 is m 1 lie tar cootammg water ileptetevt m live tvv.ws isv'iopvs 'bowed gctniinaltoo I 2 weeks earlier and seemed lo grow better throughout the growth pciiod. than oats grown m .tisirllevt ocean water. I'sing oats grown at Is ( , ihe tiist sign of germination m tlie jar containing water depleted 111 the lieavv isotopes was 4 d alter planting. On the d.o . eight plains tom ol 7^t had .ntaiueil .1 height of ft cm IK >um sign ot geitnin.ition m the i,ir mill water containmif Hk' heavier isotope coocvntiation, vs,is .diet 17 d. H> live lime Ini plants had a it.titled a tic-ighl ot ft cm in this jar, in that with w.iic-t' depleted m (he isotopes. 71 plants 1h.1i bad reached the top ot the j.ti lappiovnnjtelv 75 cint K.isltiitin1 observed that snow-water depleted in I) increases (he yield of vucumhers. radishes and spurn* wheat .omp.ued with cinitrols grown in ordinary water ot .uispec ihevl isotopic couuiosition. Me cites evt'et nucuts on (tie cite prvKhictivitv ot Ik ns and the weight gam ol suckling pigs. In both ones vvatei depicted inf) was espec iallv el Ik u.m m pi omoi mg I'nuliiiiivit. Although much has been done on the ctk\t ol I) imuliol water on hiohnuval voioiis, ae su-:gest 1I1.11 1 v'.i.Mcli *`n rlie el fee t D-vlepleled w.ikt on plain and animat aiow ilmv. pi .-w It mi till A m.itoi source ol .v.iier deplelevl m D lw 00 lot) (40" .icompaied w ith b Mi )\V is snow and ice Itoin 1 he A -i.mv 1 k polill pfuleau. Water depleted lw |si! |Ml 0 leadilv iv.nlah'c in live 1 -SA Iroui KocXv Mouni.on snow pteeipif.i'un: d'o\v 10 t IV* k-et cles a 1 i*n IlM l) (ill v . * I II V ( X (u til Sin in /kmc*-. Culonufa .VO.Vi MONS 0 8 7 3 6 0 liluntificntion of chlorinafotl Jibcn/ot'ur:iris in American tmlychUnrinatvil InphvnyU Mi'KIMIH of gmbiyis has conn ibuted to the 1 eptoduci i* i.oh-.c'* tW *vsc-t.il hud spcc'is. inc'ndmg the .|mh mli,il 1 I '/no > intii\ 1 of soulhe*n St 1 >1 land' 1 he wInk- i.m' t . 1. (/. itit't Hi \ ti/bit i'IiI I ol ScUks'-iv; tlolsVeiw .mvt On '.vow ?.vttk tTurns di>of l ako Ontario' Suspect oil c.. ,scs ilk hid? /',/ ! >f H; t2.2-un4/!hlt>rophcn> I I- I, I -i)ii-l>! >. i fieIcucl, other chlorinated biocide* atufnr then- derivatives, .mil I he puhchlonnatcd biphenyls (IK Ms). all oT which .tie present av cont.ihim.ints in the eggs1'. IK IK arc present m high concentrations m the bird populations which sutler embryonic mortality1-*. Other orgaiiochloi mo compounds which may he present in rood webs include rhe chlorinated dihcn/odioxins and the .lilorinalcd dihcn/nlmans (fig. 11. which arc toxic to embryos in amounts'-' less than I jig. J'ltey are therefore among the most toxic substances known ami .ire possible vavtses of tIvc observed monaiiiy. The cltlo'ii>alcd dihcn/odioxins ami chkuinated dibcn/nlarans, however, have proved exceedingly dtUicvdt to detect in environmental samples in the concentrations at which they .ire expected to he cnibryoioxtc''*"' The chlorinated dihen/odfoxins enter the environment as contaminants m preparations of the herbicide 2,4.?*T trefs 5 ami II) and the fungicide pCMtachlorophennl"'*'' ( hfonnated dihen/oinrans hast Ixcen (mind in a Irene It (I'hcmclor l)IV>) and a < ierntan ((lophen AM)) IK. H ami were show n to K* the active cmbryotoxic agent in these preparations'. The techniques used, however, did not detect chlorinated diben/ofurnns m an American IK 11. Aroclor 1260. We re|Hrt here the presence of chlorinated dibcn/olitrans in fVtoelor IK* 11, widely used in North America and (neat llrituin, and in the same Aroclor 1260 preparation examined previously with negative findings*. Samples of I'CII examined include: Aroclor I24K, 1254, and 1260 (196V); Aroclor 1254 (I970i: Aroclor 1016 (1972); and the same three preparations studied by Vos rt /.*: Aroclor 12((>, lot No. AK-3; Oopltcn A-ntt. lot No. 912444: ami I'licnoclnr DI>-6, lot not specified. The latter three IK Us were obtained from l)r Vos, tire others from tire Monsanto ( drtipany in tlte years indicated in parentheses. IK'lls extracted from environmental samples most often have pas chromatographic profiles snnd.tr to tlu*so of IK II formula tions containing approximately 4H. 54 or 60",, chlorine. In tlte Aroclor series, the former two IK."Ms arc equivalent to Aroclor I24H and Aroefor 1254. respectively. Aroclor 1260, I'hcnoclor 1)1*6, and (.lophen AM) all contain approximately Ml"., chlorine. Chlorinated dilvn/ofurans were identified in all Aroclor preparations except Aroclor UUft. as well as in (lophen AM) ami Phenoclor Dl*6. Aroclor lOlh is a I'CB mixture containing Mg. I Nkefelaf sttiichiicn of: n. chlorinated biphenyl, v 1 y t tt); 6, chlorinated litvioofmans, .v i r I H: c. chlonmiicd dibcn/odioxins, t i y * I - g. Wiimr I , V .''ft lulv :i !<>'< lal.fi- 1 .. .. ...( lilonu.iU'd .liKri/olm.i , ( Krhcin .md 1 tier"x loi fit II Nii'clor IMSil'ih'U A r, H.' t, * 12X4 1 |UMI| Aii'ctor 1254 (|'*7m Aioclor i:wi ii'.ren Ann lor I2t>lt ilot \K5) Aroclot 1016(1072) ( loi'licn \-r,n Plienoclot Dl' fi fit 1 n II i) 2 H 1) u 1 1 ID) o 2 125) Ml i J 11') d 7 15) '(1 6-t 1 1 ii - , i . ,1 1 i II .......... 1) 1 IS) SI) < II <! ID 1) |7.J) .. .. ,. ... II x (X||( II 1 1 IX) Ml 2'm 21) 1 ol.ll 'll |? |s 1 1) |l * !< 4 1'b I vpn-VM il as tig g l'( H 5 .dues m parentheses represent quantity as percentage iitof <fihciV"tui;iM. M), imi detected u txit up g ) Amounts of IK'll lunging Horn 10 n. 2 II g were dissolved m 400ml hexane. placed on a Horisd column (tXn {. mtciwai diameter *1 5 nun), mid eluted with: ,tn .uKliimn.il l.'.oo ml hexane, ,iml successive XIM) ml volumes eaji of 5 ", diethyl-ether hev.me, 25"., duallyt-elfier bvsaiie and ivei.vne, al ,i one of approMimiicly 1 ml mm I liemmor ixniion ><l the IK Itw.is eluted m ihe lies.me liavtion, wjiu.li was disi itrded On addition of the x . inivime. the dume' were ilottccfcd in m\ successive 41X1 ml volmncs In ilnom.iic Hie poKir solvents, cath elualc was esapoiated ii.c just in dmicss ami taken up cadi lime m a minim.il ainouni ot hexane, l.idi liaclion. m I ml hcsiine. was placed on a nitcroaliimma column" and dnled wnlh 10 ml each of I and 20"., ncth> Icne chloride in hexane These were also taken twice |int to di vness amt made to up a wihuwe u( l mt m hexane to cliimnate die nieilolem- dtlnmlc helore gus clifomatopaphic anaiyso Mitpiois ot all fractions obtained liefnre ami alter parluhmmg auv alumma were nijecied into a six find glass column Loiii.ijjimjt 3",, OVI on MS) 120 mesh Sui'dcoport m fracor M f220 ami Hewlett I'nckanl x?tHI (-as diromatoKraphs e|ui|>|xcii with "Nr electron-capture detectors 1H IU were found to be present m each fraction eluted from the I ionsil column in amounts vutlkicnt to interfere with die detection of trace com.Miun.ints. I'artiliomng in die alumina columns scpaiatol most ol Hie I'C II interference into the I"., methylene chloode fractions. On removal of this interference, different peak patterns appealed in the dtrouiutograms of the 20", methylene chloride tractions. ( ompoumls eluting m the 2<!",, methy lene chloride !> i. tion woic cidlecicil for mass spsciioine'iiv analysis using a 20; l . Uuenl st'httvt. amt a trap , .Misislmg of a cnpdlais tube 11 mm internal diameter. IPO nun long) tvrit to a 11 shape, immersed in a Ik|iii<I mu 'ecu I'.uh Meilnlcne chlonde <20 '.: 4 pi) m Itesane was imeeted mio ihe capillary as a nose, removed with j I 0 id micropipeile. and placed dneedy on die mass I'eciiomeier pit>txv l ire piidie was inserted into a (.1 C Al I MS'h>2 high resolution mass spectrometer and the sobenl icimwcd hy the lone pump I lie prol* was tapnlly nisei ted into the ton soukc ami multiple scans were recorded in the on-line high icsoluiion mode1' appiositiiiilelv 42 ,, chlorine and has tcpl.ucd Aroclor 1242 in manv applicamms, principally as die dielectric fluid in capaciliMs1* Values reported in fable I represent tile loi.d ot those compruiiuls found in Ido ml I Ionsil u.ictions 2 A total of lo 12 isomers w as idem died in each IK U. I wo chlonnalcd dilien/rduran coot.iimii.mts have been quoted lor (lie ( lophen ami IMicnocior prcviouslv*: our first analyses ol the ( lophen revealed an additional live chloi mated dilH.il/olurans* I fie st met in es contained four to sis c fitoi me ,oms V Hbvr dd'en/ofuriiirs including (hose chlorinated to a lesser extent may have (seen pi i sent in ihe lust 41X) ml li act ion but Ibis us n.d examined in detail as it contained suhsl.niii.il IK H inletfcience Kescnllv synthesised 7. l.7.X-teii.i-, 2.4,4.7.X penia and 2,3, fa*.7.hlies.ichlorodilKn/olui,in wcie used to quantilv letia-. penia-. ami hexaeldoioililuui/olui.ins, iespec iiveK I lie loimer iu authentic standards fi.nl ictcniion tunes on the OV I coinmn the same as (hose ol two ddHMi/olui.ms isotateJ from the IK II. Vox el ill* detected no Jiioriiialcd ihbcii/olurans m ait Aroclor I2(*l) piepar.itmn al a detection limit of I ppm rruetionatton aiwl esammalnm vd` die identical Aroclor IlfiO in our study cotilnin llien limlmus based on the staled Imut. but reveal the presence of 11 chlorinated diben/olutaus m (lie preparation, basing a lout conceiitraiioii ol OS pg g ' '< It ( Table 11. The same woikeis also found dietlnl ether cvinicts of the ( lophen A6M and I'Ih ihh Ioi Dl'fi to be mm li more toxic to chick emhrvos Ilian diethyl ether evli.icts ol Aroclor l2(-() Otir study confirms those liudmus on die basis of . Moiin.ncd HONS 087361 I .1 ' , i !'! !, :11 ...J \ 1:1 I mn` imiut . I Ml 200 :<o Hll. 2 <i, (>;is vUf\MiHi'jr!'.m of fraction of Aroctor t254 iiMiiniiiMiB ii niiMiffc of chlorinated biphenyls. dthen/uhirans, and naphthalenes. Idtnnlics of peaks ate goeti m (lie ICM. A, Mass mhmuhU ot peas 2, a tehavbkw'Viibenmtiii.iii dibetwofuran content: the idem leal Cfophen ami Phemndor contain M and 17 limes more total chlorinated dil'ctvofiiians. respectively, than Utc Ametov 1260. A nas thromuiogram showing components derived from the Aroclor 125-1 obtained in I MW is represented in I ig. 2. The components were eluted m the Second 400 ml l-lorisif fraction and recovered from the aht nina column in 20 methylene chloride hestme. bach ol tie numbered peaks was trapped ,s deserdk'd here. and idemtlicd by mass spcctromciric analysis. A nominal mass plot of the high resolution muss slkx'iriim of peak 2 is shoun in I ig. 2. I'lte plot includes all the ions with elemental compositions ranging to the maximum empirical formula t/ulMTH'l/H The molecular ion cluster at nominal m*e U>4 Jit) fragment* by successive losses of C I to yield the Urns at mV 269 275 and CO to the ions at .* 241 MV A minor toss of Cl from the peaks ilt 269-275 also occurs to yield the ions at w.V 2.14 23K. followed by ( O eliiuaiatioM to m-v Jitu 210. I lk' group of peaks at tnfe 152 154 are the doubly charged moh'cuhu urns. An klentic.il sficcmtm was obtained from an authentic standard of 2,1.7 N-tclrucldorodibenAifuran. I Ins latter comp.mod has a retention time identical to that of peak V Peak 2 is, therefore, a positional isomer. The accurate mass measurements for the characteristic ions arc within 2 ppm. of the calculated exact masses, beaks idem tiled on l hi* chromato gram and their retention times relative to dicldrin are a* follows: a iniMtue olTetra- and pcniuehlorohiphcnyl (I 02 T. tctracldoio- diheii/ofiuan (I JIM; pentachlorobiphensl 11.46); leiracltlorodi- iH.'ii/olnian <l.5'i; licsachloronaplulialcnc (I '*): penta- eldorohtphetivf (t,*M; hesacMmoMuplohalcnc <2.mM; ami hetMacldoronaphthalvtie 11 Uo. An alwjuot of combinvil ftactious derived tum the same Ar.wlor 1254 was treated with di.iA'methane to assess w liether any chlorinated octho-hydro\y- biphenyls tpie-fmaiisl were present. < i.is v bn uiMiograpliic analysis ol the sample Ivfoic and atlcr licalmcm resulted in idemiv ;d chromalotuaim. As luree siu.tntiues of l*< Us base entered the global environ ment17 it mas he assumed that ihecoutanunatu vliben/<ituian* 'll? ;iKo have been released m >r.porri,,ril| t,, wMCUCC. eUeiti, .illi! 'Vinlii..ll\c leiiuitl In Iv ,1,1,,hi r. ,1 Uc ' ll.m*> .1 \ UiiiU-. M I. T'.vr ,,nd ) i, \ . , r discHSMOItS. A. s Ki-Mitc i[,||iA|.m(s uj v(,l,,|,t>.;'i.d ,:i hen/oliu.ms; .uni I1 W.i'K for .is-.ki.mkc mi'. :KspcetMiuclrv lias work >\.is mh?|., .r i, ,| |n iln t .imj.Imh WiMblc Sei'ice, N.iiii'ii.il V viVc t mind.in.mi, .iml sj\s \ ( muiilinii 11 ih/hlr V/w<e. I -l V. I. A II.,VMS* Mil inn .1. Ml 1 .HIM I f'"\U ( Item/, ill\ St < ll"ii, Olhnui, < mi,A/ I i>H< S/UKC .Vi it ll( o / lib,II III, n i, < nt\t rsii\- ,>t ( n/i/,`1 inn, Mi nmi it r sim<.mi 11 \ I . Mum i-.i . \mi Hi'iKi /ry, ( ii/i/ih iiiu 77 thnteifu Murine l.iihan/ini \\ (. lin er uty of ( m<, K W. U tsrtiiu ii f.M /hit/ei'd Huy, ( ii/i/i'iniu 'J-JV'I HdtiU'.l I'ChiiMf,. I l. .o.vc|'io.t Mi? 2*. l'il'. IVesoil .iil.lrrs. ( II.I. Ol. .....I I'l.lMMIIIg OHM 1 NfwlDll, I . ,|M.I I \ , ' i'l, -V' . s 1 I |-17J I K...-I.MI,, I. Il . It.ul,l,iii.h. It n . .m.l Uutv.xM St V. t. I . Hi. I t i. Ol OTH'O') ' (nll'eilMill. ..........1 M.ilo. U ' .<n I U \.il . M. o 'lliiUlillinlliiiiii.il U 'il.' 'ii l c I'li,il ' Si* k*. tin. t .Omni. I I . m,l H,i,'. V v, )... .1 i nr* . *. lO 412 * Vii. I. (i , VinciiM.t I II V.i'Mlti M,iu\. II I , Mini .S lhm. 'I l ........ II H.:'.' Ml 11'Mill ' v..,. I (i.Util, i i/i. i. i ns n.-11'O:, ' Hi.,m'i, It. W . S"iiuiii;i|, It It llm liiiiMKH*. I >t I II W . .mil Mi,. ......... It W .In,...... mu, r. v hi I'Mi'Hli ' Iti.uiflttil.1 . K iml VlviC'i.". M I,il" 'I Uhl, I'. 1,1, Mils'll H.int-I'iii.i". U . I'l'l Mis,..... M. I,/i l lii.ii , 1111 `O I'Mil-'M. ' 1 H< 1M?I I no ? J ' I l I .,l, ' ' I'll. ^ . il III?. I* .III, Ml S. It I, c Allw.'if y ('.MHlIl'Met ' lvliven. S , .mil Hi iai, i . I |I n,' n' i M <,M. 1 1 I i',,,l,iiU'1 I) It, I. Hri'i.n. V I H.iii.m, It (. *,,,( tl.,,\,,vn ) S / !,.<(// \n , U, ... O i l;1i. |,i''iii(i.'i I ,,n- i ki' j \ / I., >./ in( v,nr <i. 11;.. u:s irn11 1 ' llm'mu.inie, A I `it.ni II W in,I M.I'Ik.i.mi l( \ II. S-,,'i K IIO I MO" 11"" i I l'^l, '1 Is ,','iii.ril. }. II . Ii m S*i i" .Il* Hi .mi . M V* . mil Je lii., H II . \.m i/ir 221. Niche breadth in llryn/mi as a test ol competition theory (ostiMuttos thvots pi edicts ttiat intr.i ,pecdie and infer- sl*:eilie tuMipetitum .l<,'uUi .l'tvi Mas - oppostle xi'vsls "'i the use "t ivsiuiho h\ p.ip. t.itiv-n, the loimcr iiuie.o me., tile latter deir\asiru-. die i.m-e .'I icmhiIm' iivtiiatlx used' . lield data siippii'lii>e lliesc piedictioiis are will known for the inMisiwiiic ,asc ' Mm ,,iC i,h- i11c mltaspeobc con.lition, and we have teen na.iW.; in lin,l an. ii l'ereiiee dam iisti.n;,Hi h. Hi , U'a.ts wOi'n . 'iiiiil,' spevies. We theielore r,pi'i! Iieie (lie urilK.ili.'ii ol hoiH piedictlOIIS IM I'v'Pei t nl , ailll'i Oil.at ("I sp.Ke h. i iw e pipto 1 te hr \ i i/i 'ait l/< ''.hurt hnetfum: Ivs .viiiisoe data sueevsttMe itie '.mu ilteits wiltim i>ilur lr uis ,m also repvotevl Inti'ii'pecitiv' ,aiii|'i.titw'ii sbouM K'si'lt m m iiwi j.ise m tile ranee <*t a iismit,,' i'c,innn used Iw a 'pevies, as at Ini'h population levels (tv .niv.inl.ices l<> am null, i.lnal .1 t'linc at (tie , lanpi tit imi 11, e .lptinimn if a lesoniie vi.idient ate otlset tsv the iiitriise nilr.ispeeilte i >mp.'Htr m' '.Mind there (I iu lui. tins k the 'piuniplc ,>l e,|iat ,'ppi>r 'mils' <>l \ la. \ 11 lm T Inietspei ltd oinpetilion mi 'la i tlier hand, should ti<nl In i.stiM the i.iinv ol ito- ii '.omi,, .H iliiiin used !' a spo i, s, .is in.In hIii.us aftemiione in ,ptot maremat loaiiiu-v i.iuuot do mi as eltiiKiilli as HONS 087362 ^ i C. Hw<>, S-.C . uJjJU, . I--* . t/J /jdLaAi Tit asxu^ ^ /u^<9 ^/ PCB*t: How Toxic? Polychlorinated biphenyls (PCB's) are recognized as ubiquitous environmental contaminants. In 1973. this worldwide problem resulted in a decision by the Organization for Economic Cooperation and Development to control the use and disposal of PCB's (/). At present, both the U.S. and Canadian governments are preparing legislation for the control of toxic substances. * The concern over PCB's is based on two factors, namely their environmental SCIENCE. VOL. iw May V, H96 persistence and their toxicity Recent re suits, however, cast doubts on the latter. Bowes et at. (2) observed concentrations of highly toxic polychlorinated diben- zofurans (PCDF's) ranging from 0.1 to 0.3 microgram per gram tn all but one of the North American PCB's (Aroclor). Earlier studies by Vos et al. (.?) had indicated that only PCB's manufactured in Japan (Kanechlor) and Europe (Clo- phen, Phenochlor) contained such impu rities. In addition. PCDF's and other by products were recently found in "pure" PCB isomers (d). The toxicity of PCDF's exceeds that of PCB's by approximately four to six orders of magnitude. Their presence in PCB's has. therefore, significant bearing on toxicity studies on PCB's. com mercial mixtures, and isomer prepara tions alike. Yet. in only a small propor tion of the scientific reports on this sub ject is the problem of PCDF impurities in PCB's discussed. Obviously, the degree of this contamination is variable with the origin and probably also with other de tails of the manufacturing processes. 1 strongly recommend, therefore, that in all future toxicity studies and for as many past studies as can be docu mented, precise information on the PCB's used (source, date of manufac ture. lot number, and so forth) be record ed. I further recommend that past experi ments for which such information is available be reevaluated in view of the strong possibility of the presence of PCDF's and their overriding (oxic ef fects. Klaus L. E. Kaiser Environment Canada, Canada Centrefor Inland Waters, Burlington. Ontario L7R4A6 RitirntM 1. Ot|ni:wn fur Economic CoopmuonarHi Ce- veiurfnem. per" felca lOl.OJ IVeivSttMJ. Paov M l-'chmary 197?), rr <- 2. G W. Bowel M ) Muivil.iil. M R OtCjn'p. A. S. Kende. J. Afnt. A'o-*J Chem. 2J. 1222 IIWI. ). J. G. Vov H L. Van Jec Man. M C Ten N'i*eer De Braw. R It Di- Vps. /'-*J CVimn. To.vml. I. W.l <I9*IU; J G V0>. NreithPrnfett. |, il>5H972l 4. M. Mi-uwv U. SunOMnini. C A W.whimciiwr, Arm CMrm 27. JI2I D. C. Ayec*. fratu'*lLnni/o*t NO. I All I9T2 MONS 087363