Arch. Environ. Contam. Toxicol. 26, 1-6 (1994)

A R C H I V E S

OF

Environmental Contamination a n d Toxicology © 1994 Springer-Verlag New York Inc.

Polychlorinated Biphenyl Congeners in Foxes in Germany from 1983 to 1991 S. Georgii 1, Gh. Bachour l, K. Failing 2, U. Eskens I , I. Elmadfa 3, H. Brunn 1 Staatl. Medizinal-, Lebensmittel-, und VeterinSxuntersuchungsamtMittelhessen, Marburger Str. 54, D-6300 Giessen, Germany 2 Arbeitsgruppe Biomathematik und Datenverabeitung am Institut for Veterin~irphysiologie,Fachbereich Veterin/irmedizinder Justus-Liebig-Universit~it,Frankfurter Str. 92, D-6300 Giessen, Germany 3 Institut f/ir Em~ihrungswissenschaftder Universit~itWien, Lammgasse 8, A-1080 Vienna, Austria Received: 8 May 1993/Revised: 1 July 1993

Abstract. Red foxes served as a biological indicator for the temporal development of environmental contamination with polychlorinated biphenyls (PCB). The concentration of PCB congeners nos. 28, 49, 52, 101, 138, 153, and 180 were analyzed in the body fat of 80 foxes (Canis vulpes) from Germany. The samples were from animals that had been submitted for examination in 1983, 1987, and 1991. Throughout this time period, a reduction was seen in the concentration of the highly chlorinated biphenyls 138, 153, and 180, whereas the concentration of the low-chlorinated congeners PCB nos. 28, 49, and 52 increased. No change in contamination with congener 101 was observed. These results show a trend toward reduction of environmental contamination with highly-chlorinated biphenyls since 1983, while contamination with low-chlorinated congeners is apparently increasing. An interesting observation is the disproportionately higher amount of 2,2',3,4,4',5,5'-hepatachlorobiphenyl (PCB 180) over that of 2,2',4,4',5,5'-hexachlorobiphenyl (PCB 153) in body-fat samples from all foxes analyzed. This phenomenon was also observed in 10 dogs examined as controls. Based on evidence from other authors of experimental toxicological studies on beagles, it appears that the fox possesses a similar cytochrome P-450 isoenzyme that can degrade 2,4,5-trichlorosubstituted aromatic compounds. As a consequence, in canines, PCB 180 which is additionally meta-chloro substituted is accumulated to a greater degree than is PCB 153.

Wild game and fish can be used as "biological indicators" to monitor contamination of the biotope with substances such as chlorinated hydrocarbons (Brunn et al. 1985; Schiller et al. 1985). Game and fish exist exclusively within their immediate environment and are, in contrast to domesticated animals,

wholly dependent upon the conditions of their local biotope (Rimkus and Wolf 1987). Foxes have been used in the past as biological indicators to detect the presence of the pesticide hexachlorobe,nzene (Koss and Manz 1976); they take their place at the upper,end of a food chain consisting of small mammals in the middle and terrestrial invertebrates and plants at the lower end. This food chain was chosen by Drescher-Kaden et al. (1978) for use as a biological indicator for chlorinated organic pesticides and polychlorinated biphenyls (PCB). In foxes, an increased accumulation of these substances over the concentrations found in the small mammals should be expected, at least in regard to the persistent highchlorinated congeners (Schulte and Acker 1974). Therefore, foxes should ideally reflect the degree of PCB contamination of their prey and consequently the contamination of their biotope. The present study was undertaken to determine whether levels of PCB contamination in fox body fat varied in animals from the same geographic area in Germany in the years 1983, 1987, and 1991. From the differences observed in PCB concentrations in foxes over an extended time period, it is possible to infer temporal changes in PCB contamination of the environment.

Materials and Methods Sample material: Material was derived from 80 red foxes Canis vulpes of various ages and both sexes, all from the area of middle-Hesse, Germany. The animals had been sent to the laboratory of the Veterinary Research Administration by local hunters for routine rabies examination. Only rabies-negative tissue was used in this study. Thirty samples were from 1983, 30 from 1987, and 20 samples were from 1991. From each animal, muscle tissue from a hind leg was excised and was homogenized for further preparation and frozen at -25°C in airtight containers. For purpose of comparison, muscle of 10 dogs of various breeds (dissection material from 1987) was exan~tined.

Chemicals

This paper contains portions of the doctoral thesis of G. Bachour Correspondence to: H. Brunn

All reagents and chromatographic materials were from E. Merck, Darmstadt, Germany and Riedel de Haen, Seelze, Germany and were

2

of the quality "for residue anlaysis" or "Pestanal," respectively. Gaschromatography standards were from Promochem GmbH, Wesel, Germany.

S. Georgii et al.

Table 1. Polychlorinated biphenyl congeners in fat of foxes from 1983, 1987, and 1991bc PCB a

Preparation and Gas Chromatography Duplicate determinations were made for every sample. Two aliquots from the sample homogenates were weighed and prepared separately. Throughout all preparation and analysis steps, efficiency of recovery was determined as described by Brunn et al. (1989). The methods used were Sohxlet extraction of lipophilic hydrocarbons and separation of the coextracted fats onto basic aluminum oxide according to Steinwandter and Buss (1975). The eluates were further purified on a minisilica gel column (Specht and Tillkes 1980). Gas-chromatographic determination of the following PCB congeners was performed on two different capillary columns according to the recommendations of the VDLUFA (1985) for the routine analysis of polychlorinated biphenyls: congener 28 (2,4,4'-tri), 49 (2,2',4,5'-tetra), 52 (2,2',5,5'-tetra), 101 (2,2',4,5,5'-penta), 138 (2,2',3,4,4',5'-hexa), 153 (2,2',4,4',5,5'hexa), and 180 (2,2',3,4,4',5,5'-heptachlorbiphenyl) (nomenclature according to Ballschmiter and Zell 1980). Two 60-m fused silica capillary columns were used (DB 1 and DB 5 columns from J&W/ Fisons, Mainz, Germany--0.25 mm inside diameter, 0.25 txm film thickness, carrier gas hydrogen, splitless injection, linear temperatureprogramming unit 2 GC 438A with electron-capture detector, Chrompack-Packard, Delft, Netherlands. The detection limit for the method described above was 1 Ixg/kg fat (PCB 28). The specificity of the gas-cfiromatographic analysis was checked by mass spectrometry of random samples (10% of the total sample material tested). In addition, to verify the complete separation of the PCB congeners, the technical mixtures Clophen A30 ® and Clophen A60® were analyzed. The concentrations of the various congeners detected were comparable to the values published by Schulte and Malisch (1983) and Schulz et al. (1989). Sample preparation and accuracy of quantitative determinations were also confirmed by analysis of standardized butterfat controls with certified PCB concentrations (Promochem GmbH, Wesel, Germany) at regular intervals.

Statistical Analysis Data management and evaluation were performed, using the following systems: an IBM AT personal computer with the statistics software package STATGRAPHICS Version 2.6 (STSC Inc. Software Publishing Group, Rockville, Maryland 20852, USA); a CDC Cyber 960 at the computing center of the University of Giessen, using the statistics package BMDP (for details see Dixon 1987). For the variables PCB nos. 138, 153 and 180, it was possible by logarithmic transformation to obtain a near-normal distribution of the test values allowing use of an ANOVA for independent random samples. If the result was significant, a pairwise mean comparison was performed using the Tukey Studentized Range method. For the other congeners determined (PCB 28, 49, 52, and 101), the distribution of the values obtained was discrete, making it necessary to use a ranking test (Kruskal-Wallis test with pairwise comparisons according to Nemenyi for significant results). Abbreviations: PCB = polychlorinated biphenyl(s); 2 = arithmetic mean; rain = minimum value; q~ = first quartile; ~ = median; q3 = third quartile; max = maximum~alue.

Results and Discussion A particular animal species is useful as a biological indicator of its given biotope, especially when comparing different territo-

28***

49***

52***

101

138"**

153"**

180"**

Year

[

min

q~

~

q3

max

1983 1987 1991 1983 1987 1991 1983 1987 1991 1983 1987 1991 1983 1987 1991 1983 1987 1991 1983 1987 1991

5 0 26 2 7 15 12 6 14 47 15 34 328 66 118 711 163 317 1544 216 596

0 0 16 0 0 0 0 0 0 0 0 5 36 14 32 91 38 94 165 65 78

0 0 23 0 0 8 0 0 4 0 6 12 89 36 53 183 76 143 283 115 205

0 0 23 0 0 16 0 0 11 15 13 28 228 46 122 531 94 242 721 151 325

0 0 27 0 16 20 0 12 21 78 23 46 345 73 145 723 179 427 2434 296 852

157 0 49 0 32 29 129 34 54 238 30 93 2721 304 306 4300 1071 1000 7885 818 2084

a PCB = polychlorinated biphenyl congener bValues in Ixg/kg fat Cn = 80 (30 animals from 1983, 30 from 1987 and 20 from 1991) ***p < 0.001; 0 indicates <1 p~g/kgfat

ries and when determining temporal changes in contamination levels. Wild game such as roe deer have been demonstrated to fulfil this requirement in regard to high-chlorinated biphenyls (Kleiminger and Holm 1985; Hessischer Minister fiir Landwirschaft und Forsten 1986). In the present study, tissue samples from 80 red foxes that had been submitted for dissection in 1983, 1987, and 1991 were examined for contamination with PCB. As seen in Table 1 and Figure 1, a significant change in contamination with congeners nos. 28, 49, 52, 138, 153, and 180 is evident throughout the 8-year test period (p < 0.001). Table 2 shows the results of pairwise comparisons between the years from which the samples derived. Regarding the high-chlorinated congeners 138, 153, and 180, contamination decreased between 1983 and 1987 in a statistically significant manner, but then increased again between 1987 and 1991, not, however, reaching the level of 1983 (see Figure 1 and Table 2). This result confirmed the apparent trend of decreasing contamination of the environment and food chain with highly chlorinated biphenyls since 1983 (Brunn 1992). On an average, levels of highly chlorinated biphenyls nos. 138, 153 and 180 in foxes from 1983 were higher than in the later years. This could possibly be the result of the foxes having varying quantities of fat tissue in the different years in which samples were taken (1.9% in 1983, 3.3% in 1987, and 1.7% in 1991). Consequently, the levels measured were recalculated on the basis of wet weight and these values were compared with the original values. It was found that correction for fat content did not in general change the outcome of the analysis of variance. The only notable change was that the difference of the average values for PCB 153 and 180 were somewhat less significant (p < 0.01) when based on these corrected values. The possibility that the higher fat content of the samples from 1987,

PolychlorinatedBiphenylsin Foxes

3

157

129

100-

238

o ,,,,

80-

on r" 0

,J

0 c

E o cO o

60-

40"

-,i-m

}

20.

O0 0 CL E

O. !

I

1

I

I

!

l

%%'%

%%%

I

I

I

% ,,o 1~

PCB52

4300

3000-

!

%%%

PCB49

PCB28

!

PCBIO1

7885

o o~

2300.

v"

~

2000-

0 :~

1500.

o

c

E o c o o

1000.

500-

rn 0 0_. I

I

I

00% PCB 138

I

I

I

%% P C B 1 53

compared to those of 1983 and 1991, exerted an influence on the results was, therefore, ruled out by statistical anlaysis of data that had been recalculated on the basis of wet weight. Table 3 shows that the samples from 1983 and 1987 were not completely homogeneous in regard to age distribution of the animals. To take into consideration a possible accumulation of polychlorinated biphenyls throughout the life-span of the animals, a further study was undertaken in which levels were

I

I

I

"6 I~ PCB 180

Fig. 1. Polychlorinated biphenyls in fat from the muscle tissue of red foxes collected in the years 1983, 1987, and 1991, presented in form of box-and-whisker plots (medians have been connected),

determined, based on fat content and wet weight, for animals of different ages (Table 3). It should be noted that the sample number decreased to 65 for these tests since no age data were provided for 15 of the 80 foxes. All results were evaluated by a two-factorial analysis of variance since a nonparametric twofactorial procedure is not available. Logarithmic transformation was applied to right-skewed distributions. The results are summarized in Table 4.

4

S. Georgii et al.

Table 2. Results of the pairwise comparisons between the values from the different years using the Tukey studentized range method or the multiple comparisons according to Nemenyi (only for parameters with significant results for the global analysis) YEARS 1983-1987

1987-1991

1983-1991

PCB a

F

WW

Fb

WWc

F

WW

28 49 52 101 138 153 180

n.s. d n.s. n.s. n.s. <0.01 <0.01 <0.01

n.s. <0.001 <0.001 n.s. <0.01 <0.01 <0.01

<0.001 <0.05 <0.05 n.s. <0.05 <0.01 <0.01

<0.001 n.s. n.s. n.s. <0.01 n.s. n.s.

<0.001 <0.001 <0.01 n.s. <0.01 <0.1 <0.05

<0.001 <0.001 <0.001 n.s. <0.01 <0.05 <0.05

aPCB = polychlorinated biphenyl congener bF = fat cWW = wet weight dn.s. = not significant Table 3. Ages of the foxes from 1983, 1987, and 1991 Age Year

< 1 year

> 1 year

Unknown

Total

1983 1987 1991

8 16 7

19 7 8

3 7 5

30 30 20

Just as above, in which age was not taken into consideration, significant annual differences were observed between concentrations ofPCB nos. 49, and 52, but not of PCB 101. The effect of the age of the animals, on the other hand, was not significant for these congeners as well as for PCB 138. For the samples from the various years studied, the concentrations of PCB nos. 138, 153, and 180 differed with a high degree of significance (p < 0.01). The significant effect of age (p < 0.05)on concentrations of PCB nos. 153 and 180 reflects an average increase of these congeners with increasing age of the animals. The differences between the years were not as clear when using the values in which the wet weight was taken into account. This may be the result of the scatter of the fat analysis values. Although the threshold of significance was not quite reached for PCB nos. 153 and 180, a reduction could be observed in the average values within all age groups for the year 1987 (values not shown). Two-factorial analysis of variance showed that the age of the foxes had no effect on the results obtained for the low-chlorinated PCB congeners studied, but for the high-chlorinated PCBs nos. 153 and 180, a weak significance was found. After conversion of the data to wet weight, a significant effect of age remained only for PCB 180 (Table 4). A statistically significant reduction in contamination of fox tissue with pentachlorbiphenyl 101 was not observed (Table 1). PCB 101 is component of both the high-chlorinated technical mixture Clophen A60 ® and the low-chlorinated mixture Clophen A30 ® (Schulte and Malisch 1983). Use of Clophen A30 ® has increased in Germany since 1980 (BGA-Schriften 4/83 1983), whereas the use of high-chlorinated mixtures has been restricted by law (10th BlmSchV 1978). A reduction in environmental contamination with Clophen A60 ® and simultaneous

increase in release of Clophen A30 ® would explain these results (see Table 1). This conjecture was strengthened by the results from 1991: The muscle tissue of the foxes in 1991 was far more contaminated with the low-chlorinated biphenyls 28, 49, and 52, based on fat content, than in 1987 or 1983 (Figure 1). The differences for PCB nos. 28, 49, and 52 were highly significant (p < 0.001) (see Table 1). A statistically significant increase over 1983, 1987, and 1991 was not found for pentachlorbiphenyl 101; however, a reduction in contamination was also not observed. Laib et al. (1991) showed weak in vivo liver-tumor initiating properties of the low-chlorinated congener 49. In addition, this congener binds covalently to DNA and proteins in liver cells (Braun et al. 1991). PCB 49 as well as other low-chlorinated congeners have been found in human breas( milk (Safe 1984; Georgii 1988). For these reasons, increasing contamination of the food chain with low-chlorinated biphenyls is clearly not desirable and should be further monitored by measurements on biological indicators such as foxes. Regarding the higher-chlorinated congeners, the ratio of the concentrations of PCB 153 to PCB 180 is noteworthy (Figure 1). The concentration of 2,2',3,4,4',5,5'-heptachlorobiphenyl (PCB 180) was consistently higher in the fat of all animals tested than was the concentration of 2,2',4,4',5,5'-hexachlorobiphenyl (PCB 153). This result stands in clear contrast to previous studies that described the presence of PCB congeners in the food chain (for a review see the report of the Senatskommission 1988). In those reports, the proportion of the congener 180 was reported to be lower than that of PCB 153. Since it seemed possible that this discrepancy was the result of a particularity of canines to selectively transport and/or metabolize certain polychlorinated biphenyls, fat tissue from 10 domestic dogs was also examined for PCB content (Table 5). As with foxes, which are also a species of the canine family, the concentration of PCB 180 in dogs exceeded the concentration of PCB 153 (Table 1, Figure 1). It has been known for some time that dogs, in contrast to other species such as monkeys and rats, can degrade (Sipes et al. 1982) the otherwise highly persistent (Schulte and Acker 1974; Safe 1984; Senatskommission 1988) 2 , 2 ' , 4 , 4 ' , 5 , 5 ' hexachlorobiphenyl. This ability seems to be the result o f an unusual synthetic capability of dogs. A cytochrome P-450

Polychlorinated Biphenyls in Foxes

5

Table 4. Results of two-factorial analysis of variance to determine the effect of the year of sample origin and the age of foxes on the average PCB concentration in fat samples and wet weight after logarithmic transformation of the data Fat

Wet weight

PCB ac

Year

Age

Interaction

Year

Age

Interaction

49 52 101 138 153 180

p< p< n.s. p< p< p<

n.s. b n.s. n.s. n.s. p < 0.05 p < 0.05

n.s. n.s. n.s. n.s. n.s. n.s.

p< p< n.s. p< p= p =

n.s. n.s. n.s. n.s. n.s. p < 0.05

n.s. n.s. n.s. n.s. n.s. n.s.

0.001 0.05 0.001 0.01 0.01

0.001 0.05 0.01 0.06 0.97

aPCB = polychlorinated biphenyl congener bn.s. = not significant CBecause the distribution of PCB 28 was not normal, no ANOVA could be performed

Table 5. Contamination of dogs with PCB congeners bc PCB a 28 49 52 101 138 153 180

x

min

qi

~

13

max

0 5 0 3 11 22 47

0 0 0 0 3 7 6

0 0 0 0 6 10 18

0 6 0 3 11 21 36

0 8 0 6 14 27 58

0 12 0 9 25 58 153

aPCB = polychlorinated biphenyl congener b Values in Ixg/kg fat °n = 10 (The animals were from 1987); 0 represents <1 p~g/kg fat

isoenzyme that can metabolize the 2,4,5-trichlorinated PCB 153 was discovered in the liver of beagles (Duignan et al. 1987). In a recent publication, it was suggested that a 2,3arenoxide may occur as the result of attack on 2,4,5-trichlorsubstituted biphenyls by microsomal liver enzymes in dogs (Ariyoshi et al. 1992). From the results presented above, as well as from the examination of fat from 10 dogs (Table 5) it appears that foxes can synthesize an analogous hepatic cytochrome P-450. Assuming the validity of the generally accepted (Sundstr6m etal. 1976; Safe 1984; Senatskommission 1988) rules for metabolism of polychlorinated biphenyls laid down by Schuite and Acker (1974), the additionally metachlorinated heptachlorobiphenyl 180 must be less-readily degraded and therefore must necessarily selectively accumulate in the liver of canines. The results of the present study show that the fox is well suited for use as a biological indicator for temporal studies of environmental contamination by polychlorinated biphenyls. The use of PCB was drastically prohibited in the Federal Republic of Germany in 1989 (PCB-, PCT-, VC-restriction 1989). The data presented here (Table 1, Figure 1) provide evidence for an increased release into the environment of low-chlorinated biphenyls deriving from diverse sources. This finding appears to be corroborated by the results of a recent study on contamination of human breast milk, in which a parallel development can be observed (Brunn 1992). In particular, low-chlorinated congeners that are metabolized via reactive intermediates (Forgue and Allen 1982) need to be critically evaluated, since they show weak tumor-initiating properties (Braun et al. 1991; Laib et al. 1991). Furthermore, measurements of PCB concentration in muscle tissue of foxes, carried out over a period of a number of years, may also show

whether the legal measures that have been taken are adequate to effectively contribute to a reduction in low-chlorinated biphenyl contamination of the food chain.

References Ariyoshi N, Koga N, Oguri K, Yoshimura H (1992) Metabolism of 2,4,5,2' ,4',5'-hexachlorobiphenyl with liver microsomes of phenobarbital-treated dog; the possible formation of PCB 2,3-arene oxide intermediate. Xenobiotica 22:1275-1290 Ballschmiter K, Zell M (1980) Analysis of polychlorinated biphenyls (PCB) by glass capillary gas chromatography. Fre,senius Z Anal Chem 302:20-31 BGA-Schrifien 4/83 (1983) Lorenz H, Neumeier G (eds) Polychlorierte Biphenyle (PCB). MMV Medizin Verlag Mfinchen, Miinchen, Germany 10. BImSchV Zehnte Verordnung zur Durchfiihrung des Bundes-lmmissionsschutzgesetzes (1978) (B~eschdinkungen von PCB, PCT, und VC) Vom 26. July 1978. Bundesgesetzblatt Teil I: 1138 BMDP: Statistical Software (1987) Dixon WL (ed) University of California Press, Berkeley, CA Braun A, Eigenbrodt E, Laib RJ, Brunn H (1991) Hepatocarcinogenicity of PCB congeners. II. Covalent binding to liver macromolecules and modification of carbohydrate metabolism. Toxicol Environ Chem 34:23-28 Brunn H, Berlich HD, Miiller FJ (1985) Residues of pesticides and polychlorinated biphenyls in game animals. Bull Environ Contain Toxicol 34:527-532 Brunn H, Georgii S, Stojanowic V, Flemmig R, Thalacker R (1989) Fremdstoffe in Lebensmitteln--Ermittlung einer t~iglichen Aufnahme mit der Nahrung I. Polychlorierte Biphenyle in ausgew~ihlten Lebensmitteln. Dtsch Lebensm Rdsch 85:239-246 Brunn H (1992) Exposition Nahrung Teil II: Fremdstoffe in Frauenmilch-Chlorierte Kohlenwasserstoffe. Emahrtmgsurnschau 39:369374 Drescher-Kaden U, Hutterer R, von Lehmann E (1978) Rfickst~inde von Organohalogenverbindungen in Kleinsaugeru verschiedener Lebensweise aus dem Rheinland. Decheniana (Bonn) 131:266-273 Duignan DB, Sipes IG, Leonard TB, Halpert JR (1987) Purification and characterization of the dog hepatic cytochrome P-450 isozyme responsible for the metabolism of 2,2',4,4', 5,5' -hex achlorobiphenyl. Arch Biochem Biophys 255:290-303 Forgue ST, Allen JR (1982) Identification of an arene oxide metabolite of 2,2',5,5'-terachlorobiphenyl by gaschromatography-mass spectrometry. Chem-Biol Interact 40:233-245 Georgii S, Muskat E, Kleinstein J, Schubring C, Bnmn H (1988) PCB-Einzelkomponenten und chlororganische Pestizide in

6

Frauenmilch in Abh/ingigkeit vonder Stilldauer. Ernahrungs-Umschau 35:352-356 Hessischer Minister fiir Landwirtschaft und Forsten (1986) Belastungen beim Rehwild. Untersuchungen von Rehwild in Hessen. Ergebnisse und Bewertungen zur Schadstoffbelastung zwischen 1980 und 1983. Wiesbaden, Germany Kleiminger J, Holm J (1985) Aufbau eines ursachenorientierten Monitoring Systems fiir Schadstoffbelastungen beim Wild 4. Wahl eines geeigneten Bioindikators ffir die Anzeige von Schadstoffen Fleischw 65:394-399 Koss G, Manz D (1976) Residues of hexachlorobenzene in wild mammals of Germany. Bull Environ Contam Toxicol 15:189-191 Laib RJ, Rose N, Brunn H (1991) Hepatocarcinogenicity of PCB congeners I. Initiation and promotion of enzyme-altered rat liver foci by 2,2',4,5'-tetra- and 2,2',4,4',5,5'-hexachlorobiphenyl. Toxicol Environ Chem 34:19-22. Polychlorinated Biphenyl-, Polychlorinated Terphenyl-, Vinyl Chloride-restriction (1989) Verordnung zum Verbot von polychlorierten Biphenylen, polychlorierten Terphenylen und zur Beschr~nkung von Vinylchlorid (PCB-, PCT, VC-Verbotsverordnung) vom 18. July 1989, Bundesgesetzblatt Teil I, pp 14821484 Rimkus G, Wolf M (1987) Schadstoflbelastung von Wild aus Schleswig-Holstein. Fleischw 67:868-873 Safe S (1984) Polychlorinated biphenyls (PCB's), and polybrominated biphenyls (PBB's): Biochemistry, toxicology and mechanism of action. CRC Crit Res Toxicol 13:319-395 Schiiler W, Brunn H, Manz D (1985) Pesticides and polychlorinated biphenyls in fish from the Lahn river. Bull Environ Contain Toxicol 34:608-616

S. Georgii et al.

Schulte E, Acker L (1974) Identifizierung und Metabolisierbarkeit von polychlorierten Biphenylen. Naturwiss 61:79-80 Schulte E, Malisch R (1983) Berechnung der wahren PCB-Gehalte in Umweltproben 1. Ermittlung der Zusammensetzung zweier technischer PCB-Gemische. Fresenius Z Anal Chem 314:545-551 Schulz DE, Petrick G, Duinker JC (1989) Complete characterization of polychlorinated biphenyl congeners in commercial Aroclor® and Clophen ® mixtures by multidimensional gas chromatographyelectron capture detection. Environ Sci Techno123:852-859 Senatskommission zur Priifung von Riickstginden in Lebensmitteln der Deutschen Forschungsgemeinschaft (1988) Mitteilung XIII Polychlorierte Biphenyle. Verlag Chemie, Weinheim, Germany Sipes IG, Stocumb ML, Perry DF, Carter DE (1982) 2,4,5,2',4',5'Hexachlorobiphenyl: Distribution, metabolism, and excretion in the dog and the monkey. Toxicol Appl Pharmaco165:264-272 Specht W, Tillkes M (1980) Gaschromatographische Bestimmung von Rfickstfinden an Pflanzenschutzmitteln nach Clean-up fiber GelChromatographie und Mini-Kieselgel-Chromatographie. 3. Mitt.: Methode zur Aufarbeitung von Lebensmitteln und Futtermitteln pflanzlicher und tierischer Herkunft fiir die Multiriickstandsbestimmung lipoid- und wasserl6slicher Pflanzenbehandlungsmittel. Fresenius Z Anal Chem 301:300-307 Steinwandter H, Buss H (1975) Eine einfache Multimatrixmethode zur Bestimmung von Chlorkohlenwasserstoff-Pestiziden. Chemosphere 1:27-30 Sundstr6m, Hutzinger O, Safe S (1976) The metabolism of chlorobiphenyls--a review. Chemosphere 5:267-298 VDLUFA-Schriftenreihe (1984) Rahmenkonzept ffir die Routineanalytik von polychlorierten Biphenylen. VDLUFA-Verlag Heft 12, Darmstadt, Germany