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PB84-232610
Polychlorinated Biphenyl Transport in
Coastal Marine Foodwebs
I
New York Univ. Medical Center, NY
PROV^ST'O-
Prepared for LIBRARY
Environmental Research Lab., Gulf Breeze, FL
Aug 84
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£684-232610
EPA-600/3-8A-083
August 1984
POLYCHLORINATED BIPHENYL TRANSPORT IN COASTAL MARINE FOODWEBS
by
Joseph M. O'Connor
Institute of Environmental Medicine
New York University Medical Center
Lanza Laboratories
Tuxedo, New York 10987
CR808006
Project Officer
Al Bourquin
Environmental Research Laboratory
U.S. Environmotnal Protection Agency
Gulf Breeze, Florida 32561
ENVIRONMENTAL RESEARCH LABORATORY
OFFICE OF RESEARCH AND DEVELOPMENT
U.S. ENVIRONMENTAL PROTECTION AGENCY
GULF BREEZE, FLORIDA 32561
NATIO'NAI TECHNICAL
INFORMATION SERVICE
" KMItHRj W COMUKt
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TECHNICAL REPORT DATA
{P!rOf mii Instruction! on tnt n: er*e htjore camf-lctint!
1. REPORT NO.
EPA-600/3-84-083
2.
3. RECIPIENT S ACCESSION NO.
J>B8 k 232610
4. TITLE AND SUBTITLE
POLYCHLORINATED BIPHENYL TRANSPORT IN COASTAL MARINE
FOODWEBS
5. REPORT DATE
August 1984
8. PERFORMING OPGANIZATION CODE
7. AUTHOB(S)
J.M. O'Connor
B. PERFORMING ORGANIZATION REPORT NO.
9. PERFORMING ORGANIZATION NAME AND ADORESS
New York University Medical Center
Institute of Environastntal Medicine
Laboratory for Environmental Studies
Tuxedo Park, New York
1O. PROGRAM ELEMENT NO.
ITCONTRACT/GRANT NO.
CR303306
12. SPONSORING AGENCY NAME AND ADDRESS
U.S. Environmental Protection Agency
Environmental Research Laboratory
Office of Research and Development
Gulf Breeze, FL 32561
13. TYPE OF REPORT AND PERIOD COVERCO
14. SPONSORING AGENCY CODE
EPA/600/04
15. SUPPLEMENTARY NOTES
16. ABSTRACT The extent to which poly-chlorinated bipneriyis ircus; may DC assmnacea
into fish from dietary sources was studied by providing known doses of
PCBs (as Aroclor 1254 in food) to striped bass and analyzing cross-gut
transport, tissue distribution and elimination. Assimilation and
elimination data from single and multiple doses for whole fish were used
to calculate rate-constants for PCB accumulation (ka) and elimination
(ke) according to one-compartment pharmacokinetic models. The data from
analysis of individual tissues were used to calculate ka and ke for
individual tissue compartments.
The major conclusions from the study are that PCBs in food represent
a major source of PCB to fish (up to SOX of total body burdens). The
PCBs obtained from food cause a rapid approach to steady state, but are
eliminated slowly with a half-time of ~ 120 hr. More than 85Z of the PCB
ingested with food Is assimilated into the tissues. The long-term model
showed that PCB burdens in striped bass exposed to food containing
different concentrations of PCB will decline slowly when levels in food
decline, but increase rapidly (902 plateau reached in 9 doses) when levels
in food increase.
Preliminary verification studies support the pharmacokinetic i»dcl
for PCB accumulation in striped bass with food .as the major source.
17.
KEY WORDS AN? COCUMEV ANALYSIS
DESCRIPTORS
b.lOENTIFIE AS/OPEN ENDED TERMS C. COSATI f irU/Oroup
18. DISTRIBUTION STATEMENT
Release to public
19 SECURITY CLASS IThit
unclassified
21 SO. OF PAGES
116
20. SECURITY CLASS
unclassified
22. PRICE
E1*A farm 2220-1 (R.». 4-77} r-evious ECCTION >* OBSOLET
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DISCLAIMER
The Information In this document has been'funded wholly or in part
by the U.S. Environmental Protection Agency under cooperative agreement
number CR 808006 to Joseph M. O'Connor, of the Institute of Environmental
Medicine, New York University Medical Center, Tuxedo, New York. It has
been subject to the Agency's peer and administrative review, and it has
been approved for publication as an EPA document. Mention of trade nanes
or commercial products does not constitute endorsement or recommendation
for use*
ii
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FOREWORD
The protection of our estuarine and coastal areas from d?..nage caused
by toxic organic pollutauts requires that regulations restricting the intro-
duction of these compounds into the environment be formulated on a sound
scientific basis. Accurate information describing dose-response
relationships for organisms and ecosystems under varying conditions is
required. The Environmental Research Laboratory, Gulf Breeze, contributes
to this information through research programs aimed at determining:
. t*ie effects of toxic organic pollutants on individual species
and communities of organisms.
. the effects of toxic organics on ecosystems processes and
components.
. the si0nificance of chemical carcinogens in the estuarine and
marine environments.
PCBs hold a unique position as an environmental contaminant because
of their ambient and biological ubiquity. Results reported here have
direct practical bearing for assessing the magnitude and extent of Hudson
River contamination and for evaluating the Incorporation of PCBs into
potential human food organisms.
^ /
,. /
Henry
Director
Environmental Research Laboratory
Gulf Breeze, Florida
iii
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ABSTRACT
The extent to which polychlorinated biphenyls (PCBs) may be assimilated
into fish from dietary sources was studied by providing known doses of
PCBs (as Aroclor 1254 in food) to striped bass and analyzing cross-gut
transport, tissue distribution and elimination. Assimilation and
elimination data from single and multiple doses for whole fish were used
to calculate rate-constants for PCB accumulation (ka) and elimination
(ke) according to one-co-ipartment pharmacokinetic models. The data from
analysis of individual tissues were used to calculate ka and ke for
individual tissue compartments.
The pharmacckinetic data were used to evaluate the importance of PCB
uptake from food, estimated body burdens arising from PCB in food, and to
calculate a long-term model for PCB accumulation in Hudson River striped bass.
The major conclusions from the study are that PCBs in food represent
a major source of PCB to fish (up to 802 of total body burdens). The
PCBs obtained from fooc" cause a rapid approach to steady state, but are
eliminated slowly with a half-time of -. 120 hr. More than 852 of the PCB
ingested with food is assimilated into the tissues. The long-term model
showed that PCB burdens in stripod bass exposed to food containing
different concentrations of PCB will decline slowly when levels in food
decline, but increase rapidly (90% plateau reached in 9 doses) when levels
in food increase.
Preliminary verification studies support the pharmacokinetic model
for PCB accumulation in Ttriped bass with food as the major source.
iv
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CONTENTS
Foreword . ..... ..... ill
Abstract iv
Acknowledgments vi
I. Introduction 1
II. Objectives and Design 5
III. Application of the Data 9
IV. Organization 10
V. Dietary Transport of PCB". in Striped Bass 11
VI. Tissue Distribution of PCB and Routes for
Elimination 36
VII. Eco-kinetic Model for PCB Accumulation in
Fishes 56
VIII. Field Test of the Eco-kinetic Model 84
References 91
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ACKNOWLEDGMENTS
The study was carried out under Cooperative Research Agreement
CR £0800', through the Gul: Breeze Environmental Research Laboratory (G3ERL)
of tne J.S. Environmental Protection Agency, Sabine Island, Gulf Breeze,
FL, 3?561. The assistance of the entire GBERL staff, under the direction
of Dr. Henry Enos (Directjr), and Dr. Andrew J. McErlean (Deputy Director),
made the project possible. Special thanks are given to Mr. Norman
Rubinstein, Project Officer, and Dr. Al W. Bourquin, Acting Chief,
Processes and Effects Branch, GBERL. We should like also to acknowledge
the comments and criticism of members of the GBERL staff: Drs. Frank
Wilkes, Tom Duke, Hap Pritchard, and Jim Clark. Dr. John Connolly of
Manhattan College and Dr. Richard Peddicord and Mr. Victor MacFarland of
the U.S. Army Engineers Waterways Experiment Station, Vicksburg, MS were
helpful throughout the ccurse of the study, as was Dr. Ronald Sloan of
the New York State Department of Environmental Conservation and Dr. -Jin Spain
of Georgia State; University.
vi
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FINAL REPCKT
Ck 808006
poLYCHLoai?:ATr:D BIPHEKYL TRANSPORT JH COASTAL HARIKE FOODWEB^
X. IHTEODUCTIQS
Ecotoxicology of the Polychlorinated Biphenyls; The polychlorinated
biphenyls (PCBs) were first used in industry as early as 1929 (Nelson.
1972). Thirty-seven years later Jensen (1966) published the first
account of PCBs appearing in the flesh of fishes taken from natural
waters. This sudden appearance of PCBs on the environmental scene was
misleading, however* in that PCB identification and quantitation were
not so ouch dependent upon their presence as upon the development of
suitable analytical techniques for their detection.
Within a few years of the discovery of PCBs in environmental sam-
ples, investigators in many locations documented the near-ubiquity of
PCB distribution in the global environment, as well as evidence f"r the
toxic effects PCBs may have on organisms (Risebrough et al., 1968). la
aquatic systems, the PCBs have been shown to be acutely toxic to shrimp,
ousters, Daphnia and various fishes (see reviews in Nelson, 1972; Hutz-
in^er et al.* 197A; Wassermann et al., 1979; National Academy of Sci-
ences, 1979). Documented chronic effects among aquatic organisms
include decreased rates of growth in oysters, decreased photosynthesis
in algae, impaired respiratory function in both vertebrates and inver-
tebrates, altered developmental patterns, skeletal abnormalities and
increase- susceptibility to disease (Duke et al., 1970; Fisher. 1975;
Wildish. 1C70; Cantixli. 1979; Mehrle et al., 1982). Even at exposure
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2.
levels known not to influence mortality or morbidity directlyt PCBs tend
to accumulate in aquatic organisms to alarming levels. In the
northeast rn United States, for example, excessively high levels of PCBs
in fisheries products (i.e., concentrations >. 5.0 *ig/g vet weight in
edible flesh) have caused closure of commercial fisheries for striped
bass (Hudson River)* flounder (New Bedford) and lobster (Hew Bedford).
Furthermore, public health advisories reco&mending reduced consumption
of fish due to PCB contamination have been issued in Massachusetts, Hew
York (coastal, estuarine regions and Great Lakes regions) and Kew Jersey
(coastal and estuarine).
Sources of PCBs to thg Coastal Marine Environment; The PCBs possess
numerous "desirable" industrial characteristics, and were widely used in
many industries. A partial list of applications includes: dielectrics,
heat exchange fluids, hydraulic fluids, plasticizers, flatae-retardant
lubricants, pesticide carriers and pigment carriers in printing inks
(Nelson, 1972). To a large extent, PCB use in industries was disper-
sive; little care was taken to prevent wastage or environmental disper-
sion. Anecdotal information suggests thac PCBs have been used as road-
sprays to recard dust, and as growth retardar.ts for roadside foliage.
The variety of uses found for PCB resulted in widespread occurrence
of PCB in the atmosphere, in surface waters, and in the sediments of
lakes, rivers and estuaries. For the most part, the contamination lev-
els seen in such regions can be ascribed to two major sources; indus-
trial discharges and effluent releases iron sewage treatment plants
(O'Connor et al.. 1982; Bopp et al.. 1981; HAS. 1979).
In the coastal marine environment there occur rather few direct
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3.
industrial discharges; however* discharges from sewage treatment plants
aze rather coinaon. Thus, for the typical coastline* the major sources
of PCS input are likely to be i) sewage discharge. 2) river runoff* and
3) atmospheric deposition. In the vicinity of major urban-industrial
areas* such as Boston* New York* Norfolk* San Francisco and other areas*
discharges into estuarine waters from industry and treatment plants
increase significantly the quantity of PCB material transported in river
discharges. In the Rev York region the transport of dredged estuarine
sediments to ocean dumpsites represents a major source of PCBs to the
Rev York Eight (O'Cocnor et al.. 1982). Likewise* iu Long Island Sound,
at the Philadelphia Cuapsite and in San Francisco* ocean disposal of
dredged material nay represent a major source of PCBs to the system.
capable of causing significant bioaccumulation in fishes and shellfish
(O'Connor and Stanford. 1979; Bopp et al., 1931; O'Connor et al.. 1982;
O'Connor and Pizza. 1984).
Fate of PCBs in the Coastal Marine Environment; Due to their low
solubility and strong adsorptive potential, PCEs in the aarine ecosystem
are likely to rocain associated with finely divided particulates, either
in the suspended or deposited state. Because the potential for desorp-
tion is low (Di Toro and Horzenpa, 1982). release to the water column
from either the deposited or suspended state is minimal (O'Connor and
Connolly. 1980; M^ckay* 1982). and accumulation by biota due to direct
water uptake is likely to be low.
In either the geologic or biologic matrix, PCBs are highly per-
sistent; th«-y are neither metabolized nor transformed to any ceasurable
extent by bacteria in the sediment* nor by the mixed function oxidase
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4.
system in organisms (World Health Organization, 1976; HAS. 1979; U.S.
EPA. 1980). In highly contaminated systems, such as the Hudson River,
New Bedford Harbor or the Duvamish Waterway, the persistence of PCB may
lead to very high levels of bioaccunulation (see, e.g., H.Y. State Dept.
of Environmental Conservation, 1981, 1982; Sloan and Arnstrong. 1982;
Brcwn et al. in press, 1S85). PCB levels in coastal narine systsns.
however, are much lower than in estuarine systems, and the levels gen-
erally found in marine fishes and shellfish are lower than in estuaries
by as much as an order of magnitude (Cahn et al., 1977; Spagnoli and
Skinner. 1977; MacLeod et al.. 1981; Boeha and Kirtzer. 1982; O'Connor
et al.. 19P2; O'Connor. 1984 in press).
kittle is presently known regarding the oechanisas of PCB transport
in coastal marine ecosystens. The objective of the Cooperative Research
Project between the NYU Medical Center and the EPA Gulf Breeze Environ-
mental Research Laboratory was to investigate and describe PCB transport
mechanisms in food webs. This final report describes experiments con-
ducted between October 1980 and October 1983 and provides analyses and
interpretation of the results as they pertain to prediction of PCB body
burdens iu fish populations.
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5.
OBJECTIVES AND DESIGN
The present Cooperative Research Agreement was part of a larger
work unit undertaken by GBERL aimed at describing the extent to which
PCBs introduced to the coastal marine environment with dredged material
night accumulate in marine fishes. The work unit had two parts. The
first* directed by itonn Rubinstein, was carried out at CBERL and was
designed to determine from microcosm studiec the transport of PCBs froa
contaminated harbor sediments to fishes* shellfishes and fish food
organisms. Results of these studies have been documented (Rubinstein et
al.» 1983 and in press). The second portion, described in this report*
was designed to study the mechanisms of PCS transport between fish food
organisms and fishes, and to provide, if possible, a description of the
rate constants for PCS assimilation due to dietary uptake. The ultimate
objective of the combined studies was to provide a predictive framework
for estimating PCB accumulation in marine fishes, and ro test the vali-
dity of our predictions by comparison of laboratory results with field
situations.
Pesien Development and Chronology; Initial stuJies encompassing the
first portion of Year I (October 1980 through April 1981) attempted to
establish the usefulness of techniques, determine proper species for
laboratory analysis, and understand potential flaws in the experimental
design. These studies are summarized in this section, and relate to
overall project execution as "rangefinding" data.
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6.
1) Species Selection:
The initial project design called for use of the hogchoker
(Trinectes raaculatus) and the winter flounder (Pseudopleuronectes aneri-
canus) as subjects for research. In fact* several species were used in
the rangefinding studies. These included hogchokers and winter
flounder* as well as white perch (Moror.g agpricana) and striped bass
fMorone saxatilis).
Criteria for selection of the major test species were: 1) ecologi-
cal niche (marine species required); 2) ease of capture and availabil-
ity; 3) ability of the species to tolerate laboratory holding condi-
tions; end A) use of the species as a hu&ao food resource. In the final
analysis* the organism chosen for detailed study was the striped bass.
In a subsequent study conducted at Gulf Breeze* we incorporated spot
(^giostonus xanthurus) into experiments* and spot studies were used in a
microcosm food-chain experiment (Rubinstein et al.• in press).
Preliminary experiments were undertaken* in which we provided
fishes with live food introduced directly to the holding aquarium. The
14
food organisms had been previously labeled with C-Aroclor 1234 in
order to provide a dietary PCB burden directly to the fish. Hogchokers.
white perch and striped bass were all treated in this manner. Analyses
of C-PCB in the holding water and determination of tissue C-PCB
masses in the fishes after exposure* however* revealed unacceptable
14
differences in the mass balance for C-PCB. Host nass balances yielded
far more than 1002 of the dose administered.
14
The problems were resolved by administering C-PCB to the fish by
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7.
gavage* a technique developed in this laboratory (see Pizza and
O'Connor* 1983) and applied most successfully to the striped bass. All
subsequent food-chain transport studies were performed using the gavage
technique* including the studies performed with spot in 1982.
2) Deteruinacion of Design:
Successful administration of food by gavage made a food-nediated
PCS transport design feasible, providing sufficient care was taken to
account in the experimental tanks for the effect on the mass balance of
I
all possible routes of FCB movement. The basic design* therefore, came
to be one in which the following elements were considered:
a) biomass of test specimens was maintained at a uniform level
b) known doses of C-PCB with a known level of radioactivity
were incorporated* such that nanogram levels in specific tis-
sues could be detected
c) excretion of PCS to the water was controlled by exposing fish
to the exposure v-*.ter» but without dietary C-PCB exposure
d) C-labeling of food was always performed using an ecologi-
cally relevant striped bass food item* Carmama tigr\rn\3
(O'Connor. 1984 in press).
3) Other Design Considerations
Two additiional studies were carried out. They were: 1) to deter-
tuine, under laboratory conditions, the relative importance of dietary
and water-derived PCB uptake; and 2) to carry out a field sampling pro-
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8.
gram (Year III) ai=ed at establishing whether PCB transport via the food
chain provides a reasonable estimate of body burden in the natural
environment.
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9.
III. APPLICATIOM fi£ THE DATA
The project was designed to provide descriptive data useful in
understanding how* and to what extent* PCD transport may occur in coa-
stal marine food-chains. It soon became clear that the data could b^
applied in a predictive manner if they were interpreted using a thermo-
dynamic, mass-balance approach. Such concepts* first applied to organo-
chlorine pesticides in fishes by Norstron et al. (1976)* were formalized
by Tbomann (1978* 1981) into a food-chain PCB uptake model. The present
study owes much to the concepts developed by Thonann (1981) and Thouann
and Connolly (1984), and was partly designed to address questions
regarding the proper value for a significant factor in their PCB models;
i.e., the ~fojd-chaia multiplier".
Since it was possible to monitor administration, assimilation, body
distribution and el initiation of C-FCB iu the test species, the results
fit precisely the phernacokinetic codeIs developed by Goldstein et al.
(1974) for dose/effect evaluation of pharmaceutical products. By com-
bining the long-term (life-cycle) modeling approach of Thonann (1978*
1981; Thonann and St. John* 1979) with the pharmacokinetic approach, we
proceeded to develop a DOdel describing and predicting PCB burdens in a
fish as determined exclusively by dietary sources (Pizza and O'Connor*
1983; O'Connor and Pizza. 1984).
It is expected that the data provided herein, as well as the exper-
imental and modeling approach, will be of value to both industry and
regulatory agencies that evaluate the long-term ecological consequences
of contaminant discharges to the environment.
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10.
IV. ORGANIZATION fl£ "I1E REPORT
Varied and diver&e subjects comprise this report. To provide sone
coherence, we have organized the report as follows:
Section V describes dietary uptake and pharnacokinetics of PCBs in
striped bass. Section VI describes the tissue transport of PCB in
striped bass, as well as conclusions regarding routes of PCB transport
and elinination. The uptake and elimination data were used in develop-
ing a pharmacokinetic nodel ta predict PCB burdens in marine fishes,
described IE Section VII, Section VIII presents the results of a field
stu-.'y aimed at verifying tLe phantacokinetic model for striped bass in
the Hudson and coastal Atlantic region. All references are collected in
Section IX; the individual sections are organized peer-revieweU publica-
tions.
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11.
JJ. DIETARY TRANSPORT fi£ PCEs XH gTRIPED B^gg
IflTRODUCZIOH
The entire food web of the Hudson estuary is contaminated with PCS
(O'Connor. 1982). It nay be assumed, theretore, the PCS accumulation by
fishes is due partly to direct uptake from water (i.e., by equilibrium
partitioning; see Branson et al.. 1975; Clayton et al.. 1977; Thonann.
1981; Cal\fano et al.. 1982) and partly due to accumulation from the
diet (Mayer et al.. 1977; Guiney and Peterson. 1980; Bruggeaan et al..
1981).
The kinetics of dietary PCB absorption in fishes received little
attention for at least two reasons: 1) the difficulty in quantifying
secondary uptake ox contaminants which desorb or dissolve from food
prior to ingestion; and 2) the difficulty in quantifying the ingested
dose. These problems were addressed by Guiney and Peterson (1980) in a
study where the ingested dose was given to fish (Saino gairdneri and
Perce flavesceiis) in sealed gelatin capsules. Thus* a knovn dose was
administered to the absorption site without secondary uptake from water*
allowing the calculation of precise distribution data and elimination
phase kinetics. To our knowledge, alimentary tract absorption rate-
constants for PCBs have not been published for any fish species.
This chapter describes experiments in which uniform doses of C-
Aroclor 1254 were given to striped bass by gavage with live food.
Absorption-site and whole-body kinetics related to uptake, elimination
and rate of accumulation of PCB body burdens were generated using the
principles of drug accumulation (Goldstein et al., 1974).
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12.
AI:D IST
ibung-of-year striped bass were collected frou the Hudson River at
Stony Point, II. Y. The fish were naintair.eo at 2 parts per thousand
Co/oo) .salinity ;:t ~ 20 C in activated-carbon filtereU aquaria for 7-14
days prior to experiments, rood was ainced earthuoms, Paphnia s?p. , and
Gaonarus ti^rinus: vie food was given for 24 hr prior to dosing. The
weight of fish usji. in the single-dose stud/ was 0.8S ±0.04 g- (dry wt; « +. s_) .
Fish used in the cultiple-dose stuciy weighed 0.7J ±. 0.04 g (dry wt) .
Camraarus t igrinu.° . an estuarine amphipod which occurs frequently in
the diet of Hudson River stripeci bass, was usec as the food organism. £.«
ti-rir.us v;ere cultured in the laboratory by the procedures of Ginn
(1977K Groups of 30U uature individuals (**• 7 .;xi total length) were
labeled vita PC3 by exposure fot 24 hr to 10 p^/L C-PC-i (unit'orniy
ring-labeled Aroclor 1254; New England Nuclear) at 2 o/oo salinity
(Peters ant! O'Connor, 1962). The animals were then reuovec fron the
exposure chauuer, rinsed in C-PCB-free water, and blotted to renove
excess water. Labeled £. ti^rinus were then loaded into £lass tubes
(1.9. = 3 ru) to a set quantity, determined froa prelininary stuoies as
tnat aaount per feeding (18 ng. dry wt ) which fxlied a stnpec bass
stonach without overextension or forcing fooU into the intestine.
Food given by Oavcge had a noninal aose of 50u r,g PC3 per
Feedings were pertorneo uy inserting the loaded glass tuoe into the eso-
phagus; tUe ration vcs gently extruaed into the stouach by tne action of
a plunger in the tute. Tne fish were then transferred to activatea-
carfcon filtered aquaria at the holdir.^ conditions. At the tiua of eccli
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13.
feeding. son.e zcou tubes vere injected into scintillation vials for
estimation ci uose.
Eeconcary uptake i;ss ^eacurec cirectly daring a nullipl -2-cose "i>
rier" study. Aquaria vere tlividec iatc two parts by barriers <.;hich
allowed free exchange of vater, but prevented passage or fish. In the
expencent conducted. tne fisn for estiuate of secondary uptake rcceiveu
two shaa t~eedin0s of £. ti^rir.us. and were ir.eld isolates froc» out in
the saue tanks with, equcl mincers of tish which had receiveu two teeo-
of C-PCD. Since Ciie or.ly source of C-PCE in the tanxs vas thac
given the experiuentai fisa by £avaoe» any C-PCL iu tne control -isi;
at tr.e end of tr.e exposure \:a.s tne result of vater uptake of PC2 elr.-.-
inatcc frcn ^C-'fCZ labeiec fisiu
Sin^le-oosa a&c nul tiple-cose espermencs were cor.ductea. In t:-.e
single-dose sf:cy, fish vere force-fee anci saiapleti at 6, 12. 2t, 4o, 72,
96 ana 12u hr after feeuin0. Fish in the groups heid for 96 and 120 iir
vere fea live C-FCD free £. ti^rir.us during the holding period.
In the cultip] e-dose stuuy, fish were force-fed 3S7 ± 13 n^ C-
PCS/eose (x ± s-- n = 1A) with dosin- interval of A8 hr. Subgroups vere
*v
analyzed at the end of each interval after r-?ceivins !• 2. or 3 doses.
Care v:as taken to reduce secondary uj talce oi: excreted PC2 by reaov-
ing feces, aric continuous filtration ot tioluin^ water tnrou-h an
activated charcoal systeu.
Fisu \:CTS scanned cy ii^iersioa in ice-'./iter ana cissected, vicr.
or^rns and rcuainir.^ carcass sections placet! in indiviaual ^lass scin-
tillation vials with teflon caps. The samples vere criec to a co.istanc
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14.
- - • /-,
wei^nt at 3D C. «rter wei^hin:,, the saaples uere settee, uith oeicr-ized
water and solubili-ec in Protcsol (I.'Ei;) for 24 hr st 50-55°C. WI.ere
accessary, staples uere decolorizec with 302 hydrogen peroxide at 50*0
for 30 iiin. After cooling, 13 r.L Econofluor (KEK) COCK tan was adoec.
Saaples uere counteo or. a Paciiarc Tri-Carb liodcl «60 Ci) liquia scintil-
lation counCer. Baci-ijround radiation and sample quenci; were accounced
for, and the instrument '.las run in the external standard, autor.atic
efriciency control i-oc!e.
Alimentary tract ana uhole-iiody levels or Ccncaniuant uere deter-
uiacd for subsequent rate-constant calculations. Or^an-spccirxc levels
were also ceterruineu, and will appear in a later publication.
INSULTS AI;D li-'i^aPa^TATioi:
Secondary absorption of excreted C-i'CS was tai.niu.ized cunu^ the
14
current uorl-;. The uhole-boay levels in ooth the C-PCS and Siiaa
exposed fisn oi the oarrier stuay vere deten..ined in oraer to calculate
percent dietary uptake. After administration of two raciolabeled feeo-
in^s (cumulative dose: 980 n^), diet uas responsible for 9o.3^ of the
body burden.
Data ircr; the single-feeding studies were normalized to percent
dose acnicistered. Ti:e "fraction absoroea per unit'ti^e should be
independent of actual aose (Decerka et al. , 1971; Goldstein et al.,
ly?4). :.."e test-v. this jy co;.uariua percent absorption of tuo C-i>C;
coses uiticrin^ by a faccor oi 2.5 (3iO n0 vs. V65 n^}; the fractioas
absorbec at 45 hr uere r.ot sijnincaatly dirrerer.t (Stuoent'e T?st cf t;
P > U.U?).
-------
15.
The amount ci I-CZ renaming at the site or aesorption f,ali..:eni.ai-y
tract) uecreaseu over tiue with tvo oovious phases ITaaie I, Figure 1;.
A ph^se of rapid decrease occurred beti/een 0 ns:a 24 hr, uefiaeo ^y a
regression line with slope = -G.G44y. The line ucrinin^ ali~:eaur.ry
tract ?C3 aecrei.se iietueen 43 and 12u ar nad a slope = -C.Ou^i. Since
vhole-booy PC3 burJen was > 30« of dose after 48 hr, ana the alimentary
tract lost FCu rapidly ( < 4% of uose resainin^ after 4o nr) (cf. 1'i^ures
1 and 2)» ve concluc.ec that the initial, rapid loss rroc tue alL-cutary
tract represented transport of PCS fro:; the ;,ut to tne reuaxncer ui t.ic
bocy. The slower removal after 24 hr uas similar to tne utiole-uooy
elimination rate, ana representea tissue eli-iinacion ratner Lnca .tosorp-
tioa. It shoula oe noted thac PC2 eliaiaaCfcd with the feces i/y 24 i;-, as
monitored in several ev.perments. accounted for < 10% oi the c.or,in-
istercc cose. In general, the alimentary tracts or the scripeu oass
were not clcareo of lood until about 24 hr after ieeuin0. T.ms. Jcr th'i
purpose cf estiuatini, sinecic constants, ue assuue tr.at the full c.ose
vas present in the fish during the period of rapid renoval frou the ali-
nentary trace.
?Ci eliriinztion frou tne body Oe^zv. soon after oral
(Table II. Figure 2). The data snow nrst order eli-irjtj.on over ti-e,
tne regression yic-loins a slope of -O
The results of tr.e .ultiple feecir.j st uay si.ou tnat f 3r separate
doses of 307 ± lj n- 14C-TC3 with a uosiUo interval cf 4o ..r. a total oi
6U* ± Jo n^ or 58-9 percent of the ciraulaf.ve dose (]161 ng) was retained
at the end of th.- third interval (Table III).
These sata ;;cy i/e cpplieu to kinetic inccels dcscriuin0 the
-------
16.
Absorption of ?CZ t'ron si:.^le dietary
Tiie ret-uctioa cf alimentary tract I-Ci level vitn
tice as c percentage cf the itainijtered cose.
Tise
(hr)
0
e
12
24
4o
72
96
120
Percent Ur.r.osorcec Dose
~: i s_
luo.OU ± l.iy
76.54 + 2.11
44.70 ± 5.49
7. 03 + C.3y
4.0G ±. 0.25
3.3o ±. 0.46
3.5v + 0.2U
2. 87 ±. 0.31
n
10
10
10
3
5
5
lu
5
-------
17.
Figure 1. Percent unafasorbed dose as a funccion of time.
PCB removal from the alimentary tract as
determined by two processes: 1) absorption of
administered dose (phase 1); and 2) elimination
from tract tissue (phase 2).
-------
ft
o
o
Phase I
95% C.I. for K0= 01031* 00181 hr"
o
c
&
Phase 2
24
48 72
Time (hr)
96
120
-------
.18.
II. Viiole-ucay elimination of PCS after sia:,le
dietary exposure. TUe reduction of bcuy PC?
level vith ti-se cs a percentage of adamisterec
dose.
Ti^ie
(hr)
0
6
12
2*.
4o
72
96
120
Percent Dose in bocy
S ± sr
luu.uu *. l.Gy
93.21 1 2.3?
33.73 + 2.29
87.33 ± 1.27
77.55 ± 6.3G
66.05 ± 5.46
60.51 ± 2.35
46.99 + 4.29
n
lu
10
1U
3
5
5
10
5
-------
19.
Figure 2. Percent dose in body as a function of time.
PCS elimination from whole-body after a
single dietary exposure.
-------
95% C.I. for Ke = 0.0054+ 0.0008 hr
I 100
O
in
O
O
o>
10
I I L
0
24 48 - 72 96 12C
Time(hr.)
-------
20.
ALLD III. Cumulative u-.ole-body PCE level trot;
dietary exposure.
Doses Cvnulative PCS Retained it Eisd
Given Dose (n&) of Interval (x ± s-J
One 3u7 295.0 ± 24.2
Tuo 774 5U4.9 ± 53.4
Three 1161 6b3.9 ± 35.1
-------
21.
incorporation or c^er-icai coi/.pouncs i.-.to or^anisi^s unicn iur."icn as
single ccnipartcencs. The equations and notation are fro;2 Goldstein et
al. (1974). The «icecic r;ocel uses coL-jr.on -aass balance eqcati^as; we
have uinicized e;ianplc-s of derivation or reatruc^eaenc, therefore, and
present only these expressions vhich apply to the interpretation of cur
experimental results.
Tiie first-order nineties of oiecary uptake of ?C!i can be describee
by follouiu^ the tine-course of elimination of the coi^ounc fro:^ tiie
absorption site (alinentary tract). The equation uefinin0 this process
is:
"k^t
" " ' Oe
where i: is tne quantity of compound placeu ac tne i.usor?tiou site at
tine 0, li is tne quantity renainiac, at tirae t, ana '<: is tne c
rate-ccsstant. The absorption rate-constant may be obtained by
regression of the lo^ unacsoroed aose against tine, since Equation lb
represeats a straijnt liri with -a negative slope = U^/2.3u. The k. uay
also be determine c cirectly by exponential curve fitting. Apply IB,
re^rcESton analysis to the data iron the absorption phase (0-24 hr of
t,ut clearance; Table I, FiSure 1) yields a 95% confidence interval
(C.I.) for the U ecual to 0.1U31 +0.0181 hr" .
3
The absorption ^.-Q f-tir.o for rCZ fro..; the Out can be aeteruir.ec o
The reaoer saculc. note tr.ac 1:1 tais ciscussiou. t.:e ter^.s nilfii^U -UG
iaii-iii^ =« used. 3y convention, e^ch has, C!:e totatioa t1/r To
-------
22.
avoid contusion, ue aave chosen to delete notation ar.ti refar to ^
ti:.-e rp»ciiicslly as relating to tne process of PCZ acsorjtion cr sant
in "steady state", iiail-liie will be used only it, relation to tae eliai-
uation of PCS fro^i the bouy.
Striped bass given a single uose of PCC with ii = 0.1031 hr" have
a
a 'calculated absorption half-ti-Q (the tiae for the PCS source to be
depleted oy 50 percent) of 6.7 hr. The sharp cr.an0e in slope after 24
hr (3-4 half-t^:-.cs) represents the end of PCS assicilution frou tne ^ut,
ano coinciccs with the ti;ae of icoii clearance trou the cliacnt-ry tract.
After 24 hr, PC2 depletion froa the
-------
23.
of 120 hr. '.Ji;ole-body elir.irucion exhioits a single or.ase fror.. Lhe tiue
of acfci-nistraticn to termination at 12u hr. Aliuen.csry tract eliuiua-
tion cf ?C3 (see figure 1; phase 2 of absorption) hau i; = 0.00«i7 i
O.UUJ? hr"1 (C. I. ). a value similar to tr.o rate-constant for \;nole-i>ody
eliaiKction. The corresponding hair- life wis 146 ur. Tnis cotifims
Coat the sliaectary tract ar.c whole-body were siuiiar vitn respect to
PCS
Hate-ccnstants for ?CE eliuLcacion frou tlie x;hole-bocy and the Out
v-ere smali (< 5:":} relative to PCS absorption (1; ) of the initial, ra^ia
a
phase. \'e chose not to apply a k correction factor to the «c_ usec in
our calculations fcr ttro rcssons. First, so^e of the PCE cliuination
irKi tr.c vhole-boay is via the bcpatic patr.vay (Piz^a, unpcolisheu
oaca). Uiiiary excrecion cf ccntonnnants. such cs PC3. ua^es the^ re-
avsxlable for assimilation in the jut. This input to the ali^encary
tract eurm0 the aosorption phase would result in - measure of !:g lower
t£3C the act-al value.
Secona. tne cata used in the kinetic aodei for absorption and
ic^tion (Tsoles I and II) show deviation equal to or greater than the 5%
by which ve r.iSht correct the icfi valus by subtracting the ^. Rather
tuan yieloiru a r^ore ueanir^ful k., the correction uouia conpound the
» ^
ezperiucntsl error without aduing to or i=iprovin0 the reliability of the
outco-e o2 che piiarr.aco.-:inecic njoCel ve present. 7or these reasons, we
;:ss^e oili-ry input cr.u tissue output to cirsec oac ar.oc,.er. and we
^ot.i in our cicLer.-.inacior. of aocorptioa rate.
Jac ^ anc K uerivcc for stripcc ^ass can be used to dcteraine
*I C
percent absorption of si^le PCS doses and ;,rovi«ic i^iiht into tr.e
-------
24.
le-poral relationships between bony ourden and aosorption race. The
equation used to calculate ciie fractional absor^ticiv or a given oose
over titse is:
-k t/('- /"• ) -I" t
S/::o = l/L(ke/ka)-l] L- C "c "a -e "e J (4)
where X/l'. is the anount of PCS in the bot-y (X) relative to tue dose
(ii ) placed st the site of aosorpticn at tiue 0. '..Te slioveu earlier tnat
tne fractional absorption of PCD in stripec bass uas independent of the
-ctucl dose.
For ar.y cose, ti:e tirie at vni.cn the Liuxiuuu vacls-cocy dose is
(t _,.) is calculated for the situitioc vnere K f- e. by:
QC-^ «i e
::e D* ':e (5)
anu tue uc::iuua fraction c.tuainea frcu a single cose (X /I'. ) v;r.erp K
L-.C.:: o
»: can ce founc by:
The single-cose data froc this stuay (Tables I and IT) yielded a
xi.- ira PC2 level (X /:! ) equcl to c5~ of the cose, at 30 hr after
O
application of the cose (t _..). A graphical presentation of fractional
absorption of PCZ in stnpec oass as ceteruined frou the kfl and kg of
our sin^le-oose stuay is si-ven i" Fi0ure 3- The ur»its of the X-axis are
presenter as .; c in ortiiir to normalize for the elinisatioa rate-con-
stant. The units can te converted to actual tiue oy civiuiu0 oy i^.
The aosor^tion rate- cf the single (.ose stucy vas rapiu, anc it
sr.culo oe ;:cte- that '.;;e approacn ta.cen yieioeC a conservative esti.-ate
of \~ . \:za the ?CL cose ueer. acnir.istered in a uore bioavailable t.atri:;
3
-------
25.
Figure 3. The fractional retention of a single dose
by firct-order absorption r.r.d elimination.
The solid curve was determined from Equation 4
ar.d the data of the? current study where ke/ka
= 0.05. A maximum of 85 percent was absorbed
at 30 hr. The other curves are presented for
comparison (Goldstein et al., 1974) at the
same ke. The case t.here ke/ka = 0 is attained
by constant input. For ke/ka = 0.50, a lower
maximum woulri be attained at a later time.
-------
K0= 0.103! hr.M Ke=0.0054 hr.
Kc/Kg
Moximum Level = 85%
Ket 0 0.2 0.4 10.6
Time(hr) 0 48 96
0.8
144
.0 12 I t.4 1.6
192 240 288
181 2JO
336
-------
26.
(e.£. . ei^ulsiiiec lipid in the intestine), ra^uer tuan in a live iood
organise which required digestion, this study i^ay have yieloed a core
neacinv,ful anu larger k . Aliuentary tract ?C3 absorption has been
a
shown to increase oy iuprovec oioavailabiiity (R.D. Vetter, Univ. of'
Georgia, Athens GA, pers. conm.; J.M. O'Connor et al., unpublished data).
Accumulation of FC3 fro;: constant input (multiple exposure) can fce
predicted froa sin0le-dcse stuaies (Morales et al. . 1979). When multi-
ple doses are £iven, ir.u the cor.ce.it ration of FC3 in the fisii (Cf) >-s •1L
steacy state, the input and output rates are equal. The oody burden (u;,
PC2/^ bouy vt) can be d'-iter^Livctl bv dLvidir.o the input rate (uj PCE/^
body vt/ar) by ic (hr~ )• TJ'is should not te cotiiusec with the terni-
?re£enteo oy Sr-nson c'i al. (1975) Wi.ere for equiiibriu-a froia
uatcr exposure, C. equaled the vcxer concentration (Cy) tiues the uptake
rate-constant (k.) divided 'oy the eliuir^tion rate-coastar.t (k.,). In
tiiat uori:. the biocc .centratijn factor uas ^ivcn as l^/k--
For tiie current work, the Sioaccuuulatios factor (2AF) is not jjiven
by k /u . For a given PCS concentratiyri in tae prey (C^). the bioaccu-
uulation factor at stezcy state is equal to the feeding rate (- prey/,;
fish/hr) tir;«s the PCS absorption efliciency divided by kg (Bruj^enan et
si.. 1901). The absorption efficiency iron the sin-la dose study vas -
3J-. A cail> raticn oJ 10r, body weight and 35% eiricicncy vould yiold a
BA? of 0.6o. Whether this iiAF is realistic can only &e cetemaeu after
a ti.jrou=h e:u:uinaticn Ci "stc-acy state .
The interpretive approach taken ."or r-ul tiple-oose studies assumes
tnat a cc-pounu can be adainistereu r.c a constant rate Uero-oruer
Nineties) in a re^-en uliere a cose U^) is .iivea at regular intervals
-------
27.
tt*}. t:cte tnat these ccncitions are u.et for oriar.is.zs iu nature by
feedin^ «t regular intervals on 3 ration uhicn is uetem::e& by ncta-
bolic requirements of the anic-al. Zero-orccr in tins case refers to a
constant rate o£ absorption winch is inceper.oent ci the una^sorcec cuar.-
tity. It lucres the fluctuations shown to exist iron first-or&er
kinetics of sin0lc-uose studies.
Such uoric vas ccne by licLecsc et al. (1900), where loosters (::.o:.:^rus
jp-r.tis^ vere feu PCE-cont£i:inatec aussels (Ilytilus cculi.s) every 4d
hr tor 6 uic. With k^ = 0.04 v'*~ . 90* of the plateau uoula uc reacr.eu
in ~ 60 vecus. T.;c constant input rate can perhaps nost easily te :.aiu-
taiuec uurrn0 cent ir.ucus-f lov uptukc stuaies vith constant coiitauiiur.t
levels. Branson et al. (1975) have shown this in the "accelcratoa
test", •-•r.ore for k = 0.21 vi;" » 9V» of plateau uould oc aci.ievuu after
22 ueciis or continuous exposure to 2,2',4.4l-tetrachlo»-ooijjr.enyl.
Ti.vaeciately iclio--:in0 aJaini^tration 01 a PCS dose, IJo, at t = C»
tae level (11) in tt.e bocy equals Ji the end of the dosing intervil»
vnere t = t*, tr.e onount in the OOGJ - jiven by Equation 3a, with t =
t*.
At tne enu or any ^iven oosin,, interval, ancl just prior to auuir.is-
tratior. or the next close, the level of PCS ia a striped bass is ^iven ty
tne expansion:
x = ::o(e"ket*)i * V*~VV * ... + ^0(e"kct*)n (7)
vhere the exponent il...r. i-ej- resents tiie nunucr of tae uose 111 the
series.
The k fs calcui^tec. fro:- t:;e -Jtripeo ozss »-cta (7^^1c III) for each
e
-------
28.
interval ci tr.a ujltiple uose stuuy \.-ere in i;ooa a^reeuenc (0. OOiy +.
O.OUui hr • ~ ±s— ); ar.G afreet. also with the sir-ile-oose stu&y (k =
O.OOi* + O.OCUo hr . Our k for stri^ea DSSS or approxiuatelv 1 j; (ary
vit) vas octeruinec over a perioa of one naii-iii's. Generally,
tioa is coservc- for longer periods of tiine. *./e cuose to liuxt vi
t^on to 5-6 days in oroer ro avoio the ccnfouncini; efrects of
radiotr:cer cilution v'uich result fro^i srcvrtr. (Guiney et al. , 1977).
The discussion of railtiplo PCS exposure in stnpeti bass will -_cal uith
Cue k (G.ChOO or ) calculated tor liie cuzulutivc oata applies Co Equa-
tion 7 uitr. tl:e e::por.cr.L n = 3.
Just ^rtcr t.ie ntn cose is atiainistcrcc, l.\e accu-.sul Jtec. aooy t>ur-
.cen (;: ) is:
H
-k t*r. -i; t*
n = :: (i-e c )/u-e e ; (8)
u O
cr.u as c l>eco_2trs lar^e, a plateau level (.1^; is ai-pro^cnec, uefn^a by:
x. = v(i"e tC } (9)
7a* fraction of plateau (f) attained by a certain uunber of acses
is oivea oy:
-k. t*R
f = l-e e (10)
/
T'..e nu^oer of* c.c-ses (n) neeoec to attain a certain fraction of plateau
cac &e octeminat; oy rcarrar.^esent of Equation 10.
Tlie jlateau level r&r the present stuay vas calculatcu to oe 15v^
u^ 7CZ for i:;uivn.ual uoses of 3o7 r.0 PC^ Oivtn at L* = -',o iir (?i0i:i-e
A). Lncer t.;e ccnaitior.?; of our experineat, plateau (O'J.J v;ould oe
reac;;ec. 37 oose r.uuoer 1"' (total tiuc 22 cays). An actual level of
-------
29.
Figure 4. Curve for chc cumulative retention of PCB from
multiple dosing. Solid lines present the actual
levels attained during the experiment. Dashed
lines are the calculated extension of the data.
The plateau burden (X ) is the steady state
CO
level attained f-oni peak values after sufficient
dosing (see text).
-------
90%
;x
i i i i i i t i
1 — I - 1 - 1 - 1 - L
TiroethOO 48 96 144 192 240 288 336 334 432 480
Dose Number I 2 345678 9 10 II
-------
30.
6/.2I of the calculated plateau was reached after the fourth uose; 00^
of plcteau voulu be attained at o.3 doses.
Secause PC2 elimination occurs between coses (;; = O.Ouao r.r~ ) t:;e
e
bocy Lur^cn will fluctuate while increasing. At plateau (A^ the fiuc-
tuacion vill be equal to X /X^; the burden returning to a co-istar.t level
after each dose. We calculated that, in -cri^ea bass, cue plateau
level should fluctuate by 24. 3S between doses, if the coses were jivuii
c.t 43 hr intervals (see Figure 4).
A smaller cose anu shorter cosing interval would reuuca tne ri-uc-
tuatioQ in bocy burden. In these experiments, ue ao=:inistcrcu an auouiit
of ?C2 vnicr., in the field, could realistically JS in0esteu over a 4C-»:r
period. PCI> concentrations in Garr-arus spp. zroa ti;e bracui^ii -.vater
portion of the Hucso-.i Uiver uere between 2 and 10 ut,/0 (ury vt) ciurir.^
the pence I97c to 19ol (O'Connors 19o2). A -roi/th ration of 102 body
vei^ht per cay for striped bass of ~ 0.0 g Jry t;t amounts to a ?CL
invest ion rate of fro-^ 160 to 300 s- per cay. or 32U to IGOu n0 r^r 4^-
iac ir.cezvai. T» ^w.iv.i-iar - o:..tiicr uos« ac - .. r c ^.^ » -i -'-•:. w 3. y ^..avcfcr
iuur-.'ii .-j-i_ ..r.ve resulteu in less fluctuation, but ;uch a re^ir.en
uoulc nave seen technically unfeasiale. It would also be unnecessary,
since for a known k^, the relation xyXQ can be detersinea for any
^ interval.
::ote that when total ti:.;e (t = t*n) is useu in Equation 10, we
define the rate of suirt frou one "steacy state" to the r.e:;t. By solv-
ing the cq-atioa for f = 0.5. the ^uili-iiiji of the saiit is s.iown to be
equal to t.-.e ^ali-lif j for elimination. The value f as a lunction ci
tuie can ce ootainet frc^ Figure 5 (froa Golustein et si., 197-i) for any
-------
31.
Figure 5. The fractional shift to steady state. For a
system with constant input rate and first-order
elimination, ke determines the time required to
attain a certain fraction (f) of plateau.
(With permission from Goldstein et al., 1974.)
-------
1.0
0.8
0.6
0.4
0.2
>
.01 .02 .04 .06 .08 .10 .20 .40-. .60 .80 1.0 2.0 4.0 6.0
kt
-------
32.
system viti. zero-oroer input, rirst-oroer output, and i.r.ova »: .
Vitr. z. :.alf- Lita of 123 hr» c;.an0as ox ?Ci input rr>to or output
rate-constant voulu cause a very slow shirt to a new steady state.
Thus, the assumption of steacy state beir.^ achievec as ti~e approaches
infinity cay be unfounded in any systen other tusn the laocratory.
Annual cycles of growth, feeuin^,. reprocaction anci miration of fish
icpose a situation where the or^anisn; is, pcruaps, always in the process
of i-niitir.^ steauy state. Physiological changes uitich occur over
discrete seasons of faro'-rtn are certain to cause snuts fro- one steacy
state to tae next (TT.o^ann. 19ol). Further cnan0es due to seasor.auly
variable je^.avior uoulc perpetuate t'.ie cnan^,e (see, e. ^. , data of '."ein-
in^er, 197S). '!ore cata ere neeced on the variability of ?C2 elimina-
tion constants in fishes, especially tr.e influence of or0anis^i size,
£ro*_'tn ano physiological condition on 1: .
The relations.-.ip of plateau to close cirects attention to sone of
tne i;ey factors in iuiluencin,, bioaccuculat ion. The plateau level t;:^
is ce;jen«-ent on PC2 dose (X ), elimination rate-constant (* ), and the
cosing interval (Equation 9). When ke and dosirlo interval (c*) arc
relatively constant, as they are for an or^anisa at a ^ivcn tice in its
lire-r.istory, tae absolute quantity of contaminant in0estec. at eacn nea)
is tr.e cetcniinant oi the boay burden. Tne quantity invested (:io)
dcper.cs on tr.e contcnincnc level -n the foou (C ) arc the bio^-ass of
r *•
fooci (ration) in^estca wurin^ cacr. interval.
This case is an idea)i=ec situation for a stripac oass of fi>:cu
weight anc netabolic rate, feecinu on a sec ..-.air.cenance ration. Ue can
only ueteruir.e snort-tom increases in ooay uuruon ur.oer sucn
-------
33.
concitions-. To pradict bioaccuuulatior«. t'.ie experimental design and
subsequent rocelin^ atteupts uust consider -rcv/th and the resultin0
decline in elimination rate (^orstron et al. > 197o; Thoaar.iit 19ol).
One ni^ac e::?ect ^rcu-th to recuce k , since the uetafaolic rate of
striped bass declines with increased weight (Keucann et al. ,
l!orstroa cc al. (J976) indicated that 'aocy weight afrected clearance
rate, but not necessarily via netabolic rate. Galliano et al. (19o2)
observed c. decrease in h between larval and youn^-of-year striped bass
exposed to PC2s ir. water. Such a reduction in k dictates a bocy burden
greater than that derivec fron: EAF calculations which GO not consider
the eftects of .jro'-Jth.
The k frc~ our single-dose stuuy was applied to a 2AF calculation
where PCL input rate was constant ano elimination t;cs iirst-orotr. la
tuis calculation, a youn^-ot-yecr stripeu oass v;as assuuca to teec twice
a cay, in0estia«, a daily ration of lOS body vei^ht. The hypothetical
fisn £rew over a 5-tionth period to 1.6 ^ (dry>, ano as an approximation
of the reduction in elimination rate, the k declined with ^rovth as
deterr.ined oy veight to the -0.3 power. The k declined to 0.0044 hr
anc the computed 3AF vas 0.70. This value is much lower than the SAF =
0.95 which veuld be calculated by surply diviuin0 the feecin- rate by
tne U ceterr^iaed after 5 nonths of ^ro-'th (C.OOAt hr ). The
c
discrepancy is expiaineu oy tr.e fact tnat tae iiAF = C. 95 would ce
attained or.iy with sumcior.c due (~ 44 days) and cessation of the
decline in i* . a 1 loving for the establishment of a new stea&y state.
This uni-ersccres the importance of reco^nizinu that jioaccuuulation is
rarely characterise oy steaoy state, uut rather is a process of unin-
terrupted plateau shifc operating as a continuum.
-------
34.
Data are available for young-of-year striped bass taken in 1978
from the Indian Point portion of the Hudson River (Califano et al., 1982;
Mehrle et al., 1982). Concentrations of PCB in these two samples were
1.59 and 2.62 jg/g (wet vt) , or about 6.4 and 10.4 ug/g (dry wt), res-
pectively. O'Connor's (1982) data for striped bass food organisms (Gamaarus
spp.) from the same portion of the Hudson averaged *v» 7 pg/g (dry wt) PCB.
Given a BAF of 0.76 and a food source with 7 yg/g PCBs. one might expect
a fish to contain 5.3 ug/g PCB (dry wt) due to diet alone.
This calculation suggests that 51 to 33% of the PCB in striped bass
is due to dietary uptake, l.'e tio not iuply that this uight ue the case
for fishes in general; direct uptake fron water is an important source
of PCB to fishes, an
-------
35.
Tne ccucei-t of proven-related plateau shift has application to
i^atin^ aoiiy burdens in fishes exposeu to varyin^ conditions of PCS
input curing oifierent life-history stages, '..'e know, for sxauple, that
when uucson ?aver stripec bass mj,rate fron riverine nursery areas to
tise lower estuary and nanne waters, they show a significant reduction
in PC3 bocy aurdea (LI1S. 19t>0; HacLeoc et al. , 1901; O'Connor et al.,
IVoi). This reduction should be cue to reuuced PCS input* since the PC3
in botn '^uter ace food in coastal regions is less than in tne estuary
(Pierce et al., 1361; O'Connor ec al., 19o2). With knowledge of the
operant 1: and the PCu levels in food and water, the oody ourden and
tiae fcr reaching the new and lower level should be calculaole, and
will be treated in a later chapter.
-------
36.
TISSUE DISTRIBUTION fl£ PC3 AHfi ROUTES £fiS ELIMI?IATIOI1
INTRODUCTION
The contamination of the Hudson River and estuary with poly chlori-
nated bipheayli (PCS) has been under study for more than ten years (Car-
citch and Tofflenire. 1932). Since the first published reports of PCS
in Hudson Rivet fishes (Nadeau and Davis. 1976)• 3 great deal of
research has centered on describing the physical transport of PCBs in
the Hudson systent and estimating trends in PCB body burdens for impor-
tant fisheries products, such as American shad (Alosa sapidissina) and
striped bass (Horone saxatilis) (Turk, 1980; Turk and Troutman, 1981;
Armstrong and Sloan. 1980; Pastel et al., 1980; Sloan and Arastrong.
1982).
Several investigators have shown that different fish tissues accu-
nulate PCBs to varying degrees. Guiney et al. (1977) and Karbonne
(1979) showed that the liver concentrated PCBs to greater levels than
other tissues in yellow perch, rainbow trout and some estuarine fish
species. Califano (1981) showed that the liver had the greatest rate of
PCB accumulation in tissues of striped bass; the fractional distribution
of the whole-body PCB burden was proportional to estimates of blood sup-
ply to different tissues. In general, the distribution of PCB in fish
tissues has been linked to lipid concentrations in tissues (Lieb et al.,
1974; Guiney and Peterson, 1980; Bru&geman et al. , 1981).
In this section, we report studies carried out to detenaine PCB
accuaulation potential in tissues of striped bass, as well as estimates
of PCB elimination rate-constants from different tissue compartments.
-------
37.
MATERIALS AMD METHODS
The data for determining PCB accumulation and elimination froa
striped bass tissues cone from the same experiments used iu cur study of
whole-body PCB uptake from dietary sources (Section V; Pizza and
O'Connor. 1983). Detailed methods for dosing striped bass with known
quantities of 14C-labelled Aroclor 1254 (New England Kuclear Corp.; HEN)
are given in that section.
All the striped bass used in these studies were taken from the Hud-
son River at either Stony Point or Croton Point, transported to the
laboratory* and held for a minimum of one week prior to use in experi-
ments. All dosing with C-FCB was done by gavage. using Camnarus
tiyrinus which had previously been allowed to accumulate known doses of
14C-PC3 (Peters and O'Connor. 1982; Pizza and O'Connor. 1983). Quanti-
ties of 14C-PCB in all the tissue and feces samples taken for analysis
were determined by liquid scintillation counting (LSC) on a Packard
Tri-Carb LSC. Samples were dried to a constant weight at 50C. weighed.
wetted with 0.1 mL deionized water and sclubilized in 1 mL Protosol
(KEN), decolorized (if necessary) with 0.1 mL 302 HjOj and fluored with
14
Econofluor cocktail (KEN). Concentrations of C-PCB in water were
determined by LSC after extracting water samples on a Waters C-18 Sep-
Pak cartridge (Pizza. 1983).
Three experiments were conducted in order to assess PCB distribu-
tion and elimination Crota tissues and organs. These were: Da single
dose study to assess «uort-term PCB uptake and tissue distribution as
well as subsequent elimination; 2) a multiple dose (n = 3) study per-
-------
38.
formed to coapare tissue burdens* proportional distribution and elimina-
tion of larger FCB doses; and 3) a secondary uptake study carried out as
a control to determine the percent nondietary uptake of PCS, as well as
tissue distributions.
In the single dose study, young striped bass (0.88 ± 0.04 g dry
veight) received a single dose of C-PCB in Gannarus: subsanples of
fish were taken 6. 12. 24, 48, 72, 96 and 120 hr after dosing. Levels of
C-PCB were detemined for gill, liver, gall bladder, alinentary tract,
brain, head and remaining carcass. PCS levels in fecal matter were
measured at 24. 48. 72 and 96 hr. PCB levels in the water were deter-
mined at 6, 24, 72 and 96 hr.
Youn&-of-year striped bass weighing 0.78 ± 0.04 g (dry wt.) were
used in the multiple dose study. Prior to each feeding, a group of fi.
j^igrinus wer» radiolabeled for 2
-------
39.
The secondary absorption study vas performed to determine the
extent to which fCBs excreted to the water after accumulation from
dietary sources were r»,-absorbed by the experimental fish. A glass bar-
rier was fitted to the center of each tank. The barrier permitted pas-
sage of water across the top two-thirds of the tank; tb«i bottom r.hird
vac fitted with a solid glass sheet. Four such barrier tanks were used
dozing this study in ord^r to accommodate 32 striped bass (1.56 ± 0.07 g
dry weight). The barriers segregated 4 PCB-exposed fish from 4 nonex-
posed fish in each tank. The tanks were equipped with air-driven
filters containing 130 g activated carbon and a small piece of polyester
fiber to trap waterborne particles.
The fish in the secondary uptake study received either two doses of
**C-PCB in Garpiarus followed by a third feeding of nonlabeled CanaatUS
{exposed), or three feedings of nonlabeled CflEaaarus (sham-exposed). The
feeding interval was 48 hr. Gill, liver, gall bladder, alinentary tract
spleen, heart, eyes, brain, head and remaining carcass were analyzed for
l*C-PCB. Feces were collected from both sides of the barrier tanks at
24-hr intervals; feces had become mixed, and were pooled for use in
balancing 14C-PCB aasses. Holding water was taken for C-PCB analysis
24, 72 and 120 hr after the start of the experiment.
Statistical analyses were perforoed as presented by Zar (1974).
Percentage of administered doee retained by tissue cooparteent* and
vhole fish were presented as the mean x plus or nicus standard error
(s-. Differences between £roup PCB levels at the different sampling
tioes were tested by a one-way analysis of variance (ANOVA). with (P) <
0.05. Where significant differences were found, a aaltiple range test
-------
40.
(Kevnan-Keuls) was performed to determine significant differences
between all possible pairs of group means.
Hinety-five percent confidence intervals (C.I.) for the PCB absorp-
tion and elimination rate constants were determined frcra the slopes and
Standard errors of the least squarts lines (Pizza and O'Connor. 1983).
Tissue compartment and whole fish PCB analysis was performed on
esaple replicates at each sampling tine. To sake the besr use of the
data* the least squares regressions used to estimate absorption and
el initiation rate-constants were perforated with tuultiple values of Y for
each X rather than by analysis of means. This permitted testing for
linearity of regression. Analysis of covariance (AKCOVA) was performed
to determine whether significant differences existed anong the elimina-
tion rate constants.
RESULTS
The data presented here for the distribution of C-FCB anong vari-
ous tissues and organs are expressed primarily as percent of the dose
administered or percent of the total body burden. Mass balancing of
administered dose was not attempted since some portion of the dose
administered was renoved froa the aquaria by the carbon filters, or by
removal of feces. The data for C-PCB in feces and water (Table IV)
show that the highest concentrations occurred 24 hr after feeding, a
time which corresponds with clearance of the gut (Pizza. 1933). Feces
produced after the period of gut clearance contained far lower concen-
trations of PCB (e.g.. Table IV; single dose study. 43 to 96 hr; secon-
dary uptake. 72 ro 144 hr).
-------
Table IV. Concentrations of 1*C-PCB In fcccs (as ug/g dry weight) and In holding water (as ng/t) during
the three striped bass studies. The listing of events of dosing with 1AC-PCB or sham dosing
provides the experimental protocol. The data arc given as the mean ±1 standard error. Numbers
of fish used for each determination are in parentheses.
Sinple Dose
Time
(hr)
0
6
24
48
72
96
120
144
Fcces
Event (np/p)
IV-
Dosing
-
4.83*1.52
(S)
0.66*0.24
(4)
0.36*0.20
(2)
0.15*0.04
(3)
-
-
Wa^er
(np/?) Event
14C-
Dosing
0.35*0.07
(2)
0.55i0.09
(8)
"c-
Dosing
0.23
(1)
0.18 l*c-
(1) Dosing
-
-
Feces
(up/e)
..
_
4.01*0.62
(3)
0.77*0.29
(3)
5.76*1,41
(J)
1.57*1.01
(3)
3.86*0.39
(3)
0.51*0.20
(3)
Water
(ng/t) Event
14C_
Dosing
^.
0.53*0.14
(3)
14C-
Doslr-
0.55*0.15
(3)
Sham
Dosing*
0.26*0.09
(3)
-
* »t»-p ^« *. » i_> I-* b u r\'
Feccs
_
2.18*0.44
(4)
0.08*0.03
(4)
1.73*0.16
(4)
0.32*0.21
(4)
0.14*0.01
(3)
0.16*0.03
(3)
Water
0.46*0.07
(4)
^^
1.00*0.14
(4)
..
0.19*0.05
(3)
0.13*0.09
(3)
14
* " C-PCB free exposure; ( ) « n
-------
42.
Concentrations of * C-PCB in the holding water were correlated with
PCB concentrations in feces in the single dose and multiple dose studies
(y = -1.21 + 11.40 x; r = 0.74). This suggests that water column, con-
centrations of PCB were due in gveat part to dissolution of PCB fron
feces into th<2 water. Regression analysis was not performed on the data
froa secondary uptake studies, since feces from exposed and unexposed
fish became mixed.
The single dose study provides a record of distribution of PCB
aooag tissues during both the assimilation phase and the elimination
phase. Except for the special case of the alimentary tract, the
greatest portion of the administered dose occurred in each tissue
between 24 and 48 hr after feeding (Table V). Except for the gill. PCS
content in each tissue decreased from the maximum until the experiment
was terminated at 120 hr. Approximately 472 of the administered dose
regained after 120 hr (Table V).
Transport of PCB to tissue compartments was rapid; after only 6
hrs. about 15* of the administered dose had been distributed among the
gill* liver, head and body musculature (carcass) (Table V); 5-72 of the
dose had been lost, presumably due to excretion across the gill surface.
since the holding water at 6 hr was already carrying a measurable quan-
tity (0.35 ng/L) of 1AC-FCB.
PCB elimination rates for body compartments were determined from
data gathered after the caxinua absorption from the PCB source (after 24
hr). The tabulated values for each conpartnent were log-transformed for
least squares linear regression analysis. The slopes of the regression
linos were used to determine the elimination rate-constant 'k ) in hr
-------
Distribution of C-PCB among tissue and organ compartments after administration of a single
dose of 0.5 UK ^C-PCB at time 0. All data arc presented as a percentage (x ± s-) of the dos
Table V.
dose
administered.
Time from
Administra-
tion (lir)
0
6
1^
24
48
72
96
120
Gill
-
1.00+0.18
1.3910.22
4.6510.86
1.9610.43
1.4910.15
2.1410.19
1.4410.14
Liver +
Gallbladder
-
2.0610.45
3.6810.78
4.0110.59
4.5310.44
3.7010.18
2.6810.19
?.. 8910.34
Alimentary
Tract
100.0011.89
76.5412.11 '
44.7015.49
7.0310.39
4.0810.26
3.8810.48
3.5410.20
2.8710.31
Head
-
4.4110.04
10.8911.60
-
22.1011.86
21.7312.16
19.7211.06
15.6312.09
Remaining
Carcass
-
9.2110.77
23.1113.07
-
44. 99*4. 27
36.0413.07
32.4411.72
24.1711.81
Whole
Fish
100.0011.89
93.2112.37
83.7312.29
87. 3311.27
77. 6516. 38
66.8515.45
60.5112.35
46.9914.29
n
10
10
10
3
5
5
10
5
-------
44.
from the equation log x = log x - k t/2.3; half-lives of the compound
o e
in the different compartments were determined frou the rate-constant as
(-la 0.5/k ) (Goldstein et al.. 1974; see also Pizza and O'Connor.
1983).
The PCB elimination data shoved linearity of regression for every
compartnent tested. The slopes cf the lino were significantly different
from zero for all compartments except the gill. The regression lines
are presented in Fig. 6. PCB levels in gill fluctuated throughout' the
experiment; the slope of the regression liue was not significantly dif-
ferent from zero.
The liver/gall bladder cocpartnent showed a steady increase froa
2.01* to 4.52 of the administered dose by 48 hr. Froo this point, the
quantity declined to 2.9% at 120 hr. The mean PCB burdens carried by
gall bladder relative to the total for this conpartraent (liver and gall
bladder) were 8.9 ± 1.5. 11,' ± 2.4. and 22.3 ± 3.1% at 6, 12. and 96
hr, respectively. The relative PCB burden in the gall bladder at 96 hr
was significantly greater than at both 6 and 12 hr. showing PCB novecent
from liver to gall bladder sonetine after 12 hr.
Liver and gall bladder, when grouped as a single coiapartmect (Table
V), showed PCB elimination with kfi = 0.0076 hr"1; the 95% CI was froo
0.0059 to 0.0093 hr~*. The calculated half-life for PCB in the
liver/gall bladder coapartnent was 91.2 hr.
The quantity of PCB in the aliaentary tract showed a rapid reduc-
tion. The mean level showed a decline at every sanpling tiue with 2.S7
i. 0.312 of the initial PCB dose remaining at 120 hr. The first 30 hr has
-------
45.
a. 2
2
1
-J L__
G:ll -1 ±
.1111.
6 r-
4
2
I — 5_
~ Liver 6 Gall Blsdder J
, ! i ! 1
f
5
, "
o
Q
v>
e>
o«
« 2
I
r
1
-5
Alirr.pnrcry TrccJ
i •
40 ,
Remoinina Ccrccss
20 « 1— L
100
60
40
_ Totol Fish
I i .
0
Figure 6.
40 80
Time(hrs)
120
-------
46.
been defined as the source absorption phase; the uptake rate was dis-
cussed in Pizza and O'Connor (1983).
The head (minus gill) was treated as a cotapartaent separate free
the renaining body. PCB elimination from this site occurred with a 952
C.I. for the rate constant equal to 0.0032 to 0.0062 hr and
corresponding half-life of 147.7 hr. PCB levels in brain were determined
separately at 6. 12. and 96 hr. The mean levels in brain relative to
the total burden in head (cdnus gill) were 12.5 ± 1.2, 11.7 ± 1.4, and
13,4 +_ 1.62, respectively. These levels were not significantly dif-
ferent, indicating that PCB elimination from the whole head is represen-
tative of brain.
The PCB elimination rate was determined for the remainder of the
fish which will be referred to as carcass (whole fish minus gill, liver,
gallbladder, alinentary tract, and head), pooled as a single co=part-
n»nt. The regression line yielded a 952 C.I. for the kfi equal to 0.0066
to 0.0092 hr"1, corresponding to a half-life of 37.3 hr.
The PC3 elininatior. rate constant for the whole body, calculated
fron the tine of oral administration to 120 hr. was 0.0054 hr"1 (952 CI
= 0.0046 to 0.0062 hr"1). When the regression was performed only for
data after maxitaun absorption, the 95% C.I. for the whole body kfi was
0.0053 to 0.0077 hr"1. These two intervals were not different. Analysis
of covariance for the regression lines of all compartments tested (other
than gill) shoved that the elimination rate constants of the different
tissue coapartuents of this study were not significantly different.
During the aultiple-dose study, the distribution of PCB in striped
-------
47.
bass was determined for one, two* and three C-PCB doses. Each dosage
was 387 ± 13 ng and they were given at 48 hr intervals. The results of
this study are presented as percentage of the retained C-PCB. dry
weight tissue concentration dig PCB/g)» and as percentage of the cumula-
tive dose found in tissues and the remaining body (Table VI). During the
multiple dose study* spleen and heart were separated from the carcass
compartment and analyzed separately for PCB.
Forty-eight h?urs after the first dose was administered, the major-
ity of the PCB retained was found in head (28.52) and carcass (57.12).
Gill, liver/gall bladder, alimentary tract, and spleen/heart each car-
ried 6% or less of the body burden. Comparing the percentage of cumula-
tive dose in this experiment to the results of the single dose study
(Table V), the reader can see that the data are essertially the same.
This verifies tissue distribution data for the single-dose study and
provides a replication of the experimental procedure.
The PCB tissue distribution pattern did not change during the two
subsequent intervals (Table VI). Among the three levels of exposure (1.
2 and 3 doses), the percentage of the whole-body 14C-PCB burden retained
by each compartment did not differ significantly.
Tissue burdens presented as a percentage of the cuaulative dose
show a decrease in cean level with increased dosing for ail compartments
analyzed, including whole fish. This decrease is the result of elimina-
tion of administered PCB during the interval.
The PCB concentration data (Table VI) show a stepwise increase for
14C-PCB in the tissues for each of che successive doses. For example,
-------
Table VI. Distribution of l^C-PCB among tissue and organ compartments measured 48 hr after administration
of 1, 2, or 3 doses of PCB. Each dose was 'v 387 np ^C-PCB. All the data are presented as x 1 s-
x •
Doses
Given
One
(n-5)
Two
(n-3)
Three
(n-5)
Percent of
retained burden
yg PCB/g (dry)
Percent of cumu-
lative dose
*
Percent of
retained burden
ug PCB/g (dry)
Percent of cumu-
dose
Percent of
retained burden
up, PCB/g (dry)
Percent of cumu-
lative dose
Gill
2.47
(+0.38)
0.33
(tO. 06)
1.92
(±0.42)
2.44
(±0.18)
0.53
(±0.10)
1.61
(±0.26)
2.10
(±0.22)
0.74
(10.07)
1.25
(±0.18)
Liver +
Gallbladder
5.94
(±0.66)
1.51
(±0.17)
4.45
(±0.43)
6.12
(±0.88)
2.98
(±0.23)
3.89
(±0.33)
6.15
(±0.34)
4.47
(±0.58)
3.63
(±0.31)
Alimentary
Tract
5.35
(±0.41)
0.54'
(±0.06)
4.00
(±0.25)
5.64
(±0.15)
1.10
(±0.11)
3.66
(±0.34)
6.48
(±1.11)
1.73
(±0.16)
3.83
(±0.71)
Spleen
+ Heart
0.57
(±0.08
0.34
(±0.06)
0.42
(i0.04)
0.58
(±0.11)
0.95
(±0.13)
0.36
(±0.04)
0.56
(±0.04)
0.79
(±0.04)
0.34
(±0.04)
Head
28.54
(±1.00)
0.41
(±0.04)
21.70
(±1.82)
30.11
(±1.12)
0.69
(±0.15)
19.48
(±1.40)
27.61
(±0.41)
1.01
(±0.08)
15.25
(±0.82)
Carcass
57. K
(±1.38)
0.32
(±0.03)
46.14
(±5.40)
55.11
(±1.90)
0.54
(±0.09)
36.21
(±4.92)
57.09
(±1.82)
0.87
(±0.07)
33.60
(±2.08)
Epaxial
Muscle
-
0.26
(±0.04)
-
_
0.58
(±0.08)
-
-
0.85
(±0.07)
-
Whole
Fish
100
0.37
(±0.04)
76.24
(±6.26)
100
0.63
(±0.11) i
65.23
(±6.90)
100
0.98
(±0.08)
58.91
(±3.28)
00
-------
49.
levels of 0.37. 0.63 and 0.98 *jg PCB/g were measured in vbole fish for
the first* second, and third feedings, respectively. The liver/gall
bladder conpartnent had the highest PCB concentration of all compart-
ments for all three exposures (1.51 ± 0.17, 2.98 ± 0.23. aud 4.47 +, 0.58
*ig/g» respectively). For each level of exposure (1. 2, or 3 doses), the
PCBs in the liver/gall bladder cocpartment were significantly greater
than in the other tissues analyzed in both concentration and rate of
increase with dose. There were no significant differences among the
other compartments. The concentration data show the overall increase in
mean levels with increased dosing.
The secondary uptake data (Table VII) showed that the anount of
*^C-PCB in the fish's body due to accumulation of caterial directly from
water was 2-3% of the total burden retained. The proportion of the
secondary body burden was also calculated for each compartnent (Table
VII). With the exception of the alimentary tract data, the percent body
harden in each conpartment agreed quite closely with Cue burdens due to
dietary uptake alone. Tiie apparently anotaalous data for the alimentary
tract are probably due to,the fish in the control chambers ingesting
PCB-contaminated feces.
DISCUSSION
These studies of the fate acd distribution of PCBs among tissue
compartments in striped bass show evidence of rapid and dynaaic noveaent
from the site of absorption to the tissue. Further, it can be seen that
there exist tissue-specific differences in PCB concentration, and that
the major route for PCB eliaination is via the hepatic pathway.
-------
Table VII. Results of the secondary uptake studies In which the non-dosed fish were exposed only to
14c-PCB In water after elimination from fish receiving two doses of 14C-PCB In food. The
d-ita arc presented as the mean of percent of total dose retained, rip, of l'«C-PCB retained,
percent of retained body burden in tissue, and the percent tissue burden In non-dosed fish
compared to dosod fish.
% total dose
(980 ng) in tissue
Dosed Non-dosed •
Gill
Liver & gall
bladder
Alimentary
tract
Spleen &
heart
Head
Carcass
Whole fish
4.32
3.33
6.86
0.30
15. A2
A3. 69
73.92
0.06
0.07
0.14
n.d.
0.29
0.95
1.51
^C-PCB mass X retained
(ng) in tissue dose In tlpsue
Dosed Non-dosed Dosed Non-dosed
42.3/4
32.63
67.23
2.94
151.12
423.16
724.42
0.59 5.84 4.00
0.69 A. 50 4.66
1.37 9.28 9.26
n.d. 0.41
2.84 20.86 19.19
9.31 59.10 62.90
14.80
X ng ^C-PCB
retained
Non-dosed/
Dosed
1.40
2.12
2.04
-
1.88
2.17
2.04
Ol
o
-------
51.
The combined results of the single dcse and multiple cose study
demonstrate that the onset of PCS assimilation occurs within six hours
of feeding, and that distribution of the first and subsequent doses
among tissue comparments in the striped bass is uniform. In a physio-
logical sense, therefore, the fate of PCBs ingested by fishes is similar
to that found for drugs in general (Goldstein et al.. 1974) and for PCBs
in particular (Morales et al.. 1979) anong mammals.
The consistency with which the administered dose of PCB was distri-
buted among the tissue compartments in striped bass also imposes a gra-
dual increase in boc.-y burden with exposure. Such appears to be the cast
whether fishes are exposed to PCB in the diet (as in this study) or in
the water (Branson et al.. 1975; Mayer et al.. 1977; Califano et al..
1982). While the tissue distribution of PCBs is apparently not affected
at low level exposures, it remains to be determined whether the sane
patterns hold true for high-level exposures in heavily contaminated
environments. It is possible that conpartaents may become overloaded
with high level exposure, and that tissue distributions would be
altered, thus leading to adverse physiological effects. Such data are
not available in the literature.
We speculate, however, that for PCB burdens which occur amon,;
fishes in the heavily contaminated Hudson River and estuary, tissue dis-
tribution of PC3 remains similar over concentrations o£ more than two
orders of magnitude. Available data on three species (ifettUXS MMtilii.
H. ,^ricana and J.n-nsCLCS MKUl^) Sug£est that the proportions of
PCB in muscle, liver and other tissues are similar whether body burdens
io nature are 0.5 *g/g (dry weight ) or 40 *g/g (dry weight). That over-
-------
52.
loading of tissue cocpartaents and toxic effects apparently does not
occur for PCBs in fishes is supported by the current absence of data to
support a relationship between body burdens and physiological effect in
natural populations of estuarine and aarine fishes.
Except for the liver/£all bladder cocpartnent, PCS distribution to
striped bass tissue was proportional to the mass of tissue. Califano
(1981) suggested that this was related to the volume and rate of
arterial blood supply to each tissue coapartotnt. For dietary expo-
sures* the liver may be expected to accunulate increased levels of PCS
since the hepatic portal circulation nay carry a large portion of the
assiailated dietary burden directly to the liver. In the current study
the liver/gall bladder coapartnent contained PCBs at levels about four
tines higher than in all other body corpartaents. The sane relationship
is generally found in environaental sazaples of marine fishes (Boehia and
Uirtzer. 1982; ftacLeod et si.* 1931} and in laboratory studies of direct
water uptake (Califano. 1931; Pizza, unpublished data). Since direct
water uptake of PCS results in the suiae magnitude of PCB accumulation in
the liver as dietary exposure (Califano. 1981). hepatic portal circula-
tion cannot be the full explanation for increased liver burdens.
Rather, the affinity of PCS for liver tissue asust be associated either
with the role of liver in biotransformation of nonpolar compounds, or
with the high lipid content of liver tissue in fishes.
The rate-ci-nstanus for PCB elimination frota the various tissues
neasured were, except for the gill, quite siniiar. This demonstrates
that partitioning to lip-.d in tissues was probably not occurring in the
experiments conducted here. It also demonstrates that the affinity of
-------
53.
liver for PCS is due more to metabolic function than partitioning to a
chemical or structural entity unique to liver tissue. Indeed* since the
elimination rate constants for all tissues except the gill were similar*
and since liver PCS concentrations were greater than other tissues by a
factor of about A, then it follows that PCS turnover rate in the liver
is about four times greater than in other striped bass tissues.
Whether these facts can be used to estimate the Bass of PCB elim-
inated fron the fish via the hepatic pathway retaains unclear. In stu-
dies of PCB elimination by namnals and birds* investigators have docu-
mented the presence of PCBs or PCB aetabolites in urine and fecal
material (Hutzinger et al.. 1972; Morales et al.. 1979). In a study by
Morales et al. (1979)* the PCB was given either by intraperitoneal
injection or in drinking water. In both cases the PCB was present in
feces. clearly demonstrating the nepatic-bile pathway for PCB elinina-
tion. Helancon and Lech (1976) ;.'ound PCB in the bile of fishes fed
PCB-contacinated food. In the present study. PCB in the bile increased
two-fold by 96 hr after feeding. Presumably. PCB in bile will be
excreted to the intestine for eventual elimination with fecec.
It has not been demonstrated, however, to what extent PCBs in bile
nay be reabsorbed in the gut of fishes, ttorgstrora (1974) suggests that
lipids. triglycerides and hydrocarbons present in the diet of fishes
require enulsification sy bile prior to absorption across the intestinal
surface. Bile-associated PCBs, therefore, nay be partially reabsorbed in
the intestine. Certainly sone portion is excreted in feces, as shown ty
the PCB concentrations in fecal matter observed in our studies, but the
.atter of the nagnitude of the hepatic pathway in PCB elimination in
-------
54.
fishes certainly deserves further study.
The question of PCB elinination across the gill has been demon-
strated by other workers (Califano, 1981; Guiney et al., 1977). The
results of this study show that there was essentially no loss of PCB (as
percent dose) fron the striped bass gill tissue over the 120 hr eliaina-
tion study. As with the other tissue conpartnents, the concentration of
PCB in the gill increased when three successive doses of PCB were given.
It is possible that throughout all the «.xperiaents the striped bass gill
tissue renained in dynamic equilibrium with the water in the aquaria.
Due to continuing PCB input fron other tissues, conbined with gradual
loss to the water across the gill, we may have been unable to detect
changes in either PCB concentration or proportion of adninistered dose
in the gill.
The results for youn&-of-year striped bass indicate tnat for
extreuely low level PCB exposure (< 1.0 *iS). the whole-body distribution
of PC3 is not affected by an increase in burden. Since the lipid con-
tent varies froo cocpartuent to conpartuent in fishes Uieb et al..
1974; Cruder et al.. 1975). the possibility exists that the lipid-
oediated distribution of organochlorine contaainants rcay be secondary to
an initial low level situation where ?CB partitioning is determined by a
tissue constituent which is uore unifomiy distributed than lipid.
Indeed, lipid content is unlikely to be t, e only determinant of distri-
bution since discrepancies exist between lipid and PCB content of cer-
tain tissues (Peterson and Guiney. 1979). Movement of PCS to lipid pos-
sibly occurs only after the prinary site is saturated. This is coa-
pletely conjectural, and studies on the effects of body burden and lipid
------- An error occurred while trying to OCR this image.
-------
56.
VII. ECOKINETIC MODEL FOR PCB ACCUMULATION IN FISHES
INTRODUCTION
Contauinant loads to the marine ecosystem adjacent to New
York and New Jersey have been well documented (Mueller et al..
19S2). Aaong the core important are the polychlorinated biphenyls
(PCBs), due prinarily to their abundance in the Uudson-Raritan
systea (Bopp et al.. 1981; O'Connor et al.. 1982), their toxicity
(National Acadeay of Sciences. 1979>, and their potential to cause
chronic effects in anina1 and human populations (Kuratsune. 1976;
Henrie et al.. 1982).
Most of the PCB contact i nation in the New York Bight derives
from ocean dimping of sewage sludge and waste dredged material
(Table VIII).Shen relative PCB contribution from direct discharges
is considered and integrated according to typical flow patterns in
the Bight, expected water concentrations should be greatest in the
vicinity of the N.Y. Bight ocean disposal sites. Actual data from
• variety of studies shows this to be the case. We have calcu-
lated that the elevated PCB levels near the New York Bight dump-
sites derive in roughly equal portions from dredged material and
scrags sludge. The increased PCB levels in the water column
increase the potential for PCB uptake in all trophic levels of the
Bight ecosystem (Vynan and O'Connors, 1981; Califano et al.. 1982;
Brown et al.. 1982).
The majority of PCE placed in the Bight system with dredged
-------
57.
Table VIII.Estimated PCB incuts to the N.Y. Bight Apex, in Kg/year.
Source
Atmospheric
Municipal Wastewater
Dredged Material0
Sewage Sludge
A
Hudson Plu»ne (part.)
Hudson Plune (dissolveu)
Totals
Max.
490
42
3500
1300
1037
480
6849
% Total
7
0.6
51
19
15
7
996
Min.
34
42
1800
750
62
240
2928
Z Total
1
1
61
26
2
8 '
99
Assuir.es 1.14 m/year precipitation at 15 (min) and 215 (max) ng/2. PCB.
99.1 MGD direct wastewater flow; all secondary at 0.3 vg/i PCB.
From Bopp et al. (1981; r.in) and O'Connor et al. (1982; max).
Based upon estimates from West and Hatcher (1980), Bopp et al. (1981) and
O'Connor et al. (1982).
Plume flow assumed to be 6.6 x 10 Si/day, carrying 3 (rain) and 50 (max) mg/Jl
solids at O.S6 ug/£ PCBs for particulate load, and 10 ng/Jl (nin) and 20 ng/2.
(max) for dissolved load. (See Mueller et al., 1982).
-------
58.
materials remains associated with deposited participates. Coring
t
studies at the dredged material dumpsite in the Mew York Bight
(NYDMC. 1982) show that PCS levels vary with depth of core. Ditaro
et al. (in press) have shown that PCD mobilization from deposited
sediments is slow; vertical migration is estimated to be on the
order of millimeters per year. Thus, the contribution of dredged
material to PCS levels in the New York Bight water column is asso-
ciated primarily with losses which occur during the dumping pro-
cess. Tavoloro (1982) has estimated a dry mass loss of ~ 4% dur-
ing dumping. Overall PCB losses during the dumping process may be
on the order of 1ST).
With good reason, it has been concluded that activities which
contribute to PCB levels in N.Y. Bight fishes should be minimized.
In an attempt to determine how dredged material duuping affects
PCB body burdens in fishes, several investigations have evaluated
the rates and routes of PCB transport in marine ecosystems
(O'Brien and Cere. 1979; Rubinstein et al., 1983. Once trans-
spot t mechanisms are understood, predictive models cay be formu-
lated regarding the extent to which PCBs in sediment nay cause
increased body burdens. If unacceptable PCB .burdens in marine
organisms (e.g., 1 ug/g, 5 jig/g) can be related to nud dumping and
the process of accumulation is well understood, managers and regu-
lators can take steps to reduce or eliminate the problem.
-------
59.
Since the early 1970's it has been thought that fishes accu-
•
PCC directly from water (Hamelink et al., 1971; Neely et
al.. 1974). Experimentally derived bioconcentration factors (8CF)
predictive of "steady state" burdens in fishes have been published
widely (TableIX); uptake mechanises based upon octanol-water par-
tition coefficients and lipid solubility of PCB have been proposed
(i.e.. the equilibrium partition theory; Neely et al.. 1974; Bran-
son et al.. 1975; Mackay. 1982). the sane mechanisms have been
proposed to explain PCB accumulation in zooplankton (Clayton et
ml.. 1977; Pavlon and Dexter. 1979).
Several factors mitigate agaiast the equilibrium partition
theory as the full explanation for PCC burdens in marine fishes.
First, the concept was developed using pure, dissolved compounds
in relatively particle-free water. Under natural circumstances
sea water contains many particles to which PCBs are likely to sorb
(Hiraizuni et al.. 1979; Nau-Ritter et al.. 1982). For striped
bass (Horone saxatilis). Califano et al. (1982) shewed that the
presence of particles in bioassay water decreased the quantity of
PCB available for uptake, and that body burden was directly
related tc "available" FCB rather than total PCB.
Second, published BCF data generally derive from experiments
of long duration, >. 5 days. Under such circunstances. organisms
oust be fed during the test, and the proportion of the PCB
-------
Table lX. Bioconcontratlon of various A*-oclor$ In fish.
Organism
Coimvrdal
Aroclor
Mixture
Exposure
Conccnlr.Ulon
iifi l']>
Exposure
Tino
.toll
BCF
Reference
Channel catfish
(Ictalurus punctatus}
1243
1254
5.8
2.4
77
77
5.6 x 104
6.1 x 1(T
Mjyer et al.,
1977
Dluegill sunfish
(L£££^ll ny.a'ochiriis)
1248
1254
2-10
2-10
chronic 2.6 to 7.1 StalUngs and
chronic x 104 Mayer, 1972
Brcok trout (fry)
(Sjlvelinjs fon Ural's)
1254
6.2
118
4.6 x 10* Mauck et al., 1978
Spot 1254
(U'iostomi
-------
61.
accumulated with contaminated food was not accounted for in these
designs. Many studies have shown that fo'od material, both living
and dead, accumulates PCB rapidly (tfysan and O'Connor s,'1981;
Peters and O'Connor. 1982). providing a secondary route of PCB
uptake in th- test chamber. Peters and O'Connor (1982), for exam-
ple, showed that the common striped bass food organisms Gacinarus
»nd Keonvsis accumulated up to 2 ug/g PCB froa water in less than
10 hours exposure to a concentration of 1 ug/L. Inanimate food
nay accumulate PCB just as rapidly (Wyman and O'Connors. 1981).
Thus. BCF values calculated £rou Ions-tern exposures inclu-i- -
dietary uptake jo-.ponent not accounted for in application of the
data to equilibrium partitioning theory.
Third. »nd perhaps most importantly, equilibrium partition
calculations for PCB bioconcentration generally yield estimates
which are low. relative to field observations (Table X). Given
the potential importance of PCB as a toxicant in natural systems.
we feel it is unwise to rely heavily upon such "orcer-of-
magnitude" estimates. Given the knowledge that all parts of the
.arioe food web contain PCB (MacLeod et al.. 1981; O'Connor et
.1.. 1982). and that cross-gut assimilation of PCB in fishes
approaches 90ft (Pizza and O'Connor. 1983. ' we stress that PCB
ia fishes derive in some significant part from the food. Recently
published models for contaminant transport in fishes and plankton
demonstrate that dietary sources *.y be the Pri*e determinant of
-------
62
Table X- Calculation of expected PCS body burdens in fishes from equilibrium
partitioning basec upon Neu York Bight data.
Kin Max^
Water column PCB concentration (ng/2.)
Particulate/dissolved ratio
Dissolved (available) PCB (ng/£)
Bioconcentration factor
10
0.67
6.7
IxlO4
60
0.67
27
IxlO4
Expected concentration (rg/g fish) O-07
£
Observed concentrations (^g/g)
, , . 0.6-3.8
Striped bass
Winter flounder
Atlantic tnackerel
r . 0.7-3.6
Bluefisa
. 0.5-0.8
Anerican eel
0.6 .
Tautog
Concentrations derived fro, Lee (1977), Lee and Ja.es (1978), IEC (1979),
Pequegnat et al. (1950) and MacLeod et al. (19S1).
"
BCF
tion (see text).
A , „ - ^ ^\ „ nrF therein the water value equals ng
*
thousand salinity.
« Data fro, O'Connor et al.. 1982; N.Y. State DEC, 1981; 1982; K.J.
aa
of Environmental Protection, 1982.
-------
63.
PCB body burdens (Thonann, 1981; Brown et al.. 1982) (Fig. 1).
Studies of PCB uptake fron diet have been czrried out in our
laboratory for a variety of fishes and crustaceans (Califano et
ml.. 1980. 19S2; Califano, 1981; Pinkne/. 1932; Pizza. 1983; Pizza
and O'Connor. 1983).' The remainder of this paper provides the
results of our food chain transport studies of PCD in marine
fishes, principally striped bass. The concepts presented here are
based upon pharnacokinc tic relationships (Goldstein et al., 1974) ;- Phar-
nacokinetics have been applied to questions of pesticide uptake in
fishes by Krzeminski et al. (1977) and similar principles underlie
the recent work of Thocann (1981) in his efforts to model PCB and
cadninn accumulation ii fishes. We propose here a seasonally vari-
able, pharnacokinetic model to predict dietary accumulation of PCB
in fishes.
METHODS
The techniques csed in these studies were developed by Cali-
fano et al. (19S2) and by Pizza (1983). Complete details of the
pharmacokinetic approach to PCB studies are available in Pizza
(1983; see also Pizza and O'Con&or, 1983). To sumnsrlee, an
evaluation of the assimilation and excretion of a compound
required eopirical data as to the rate of assinilation from the
absorption site (k ). and the rate of loss of the coopound (ke>
from some physiological pool. The pool we used was the entire
-------
64.
Fig. 1. Schematic of ecological and physiological factors influ-
encing PCE accumulation in fialjes. Note the separation
of food and water sources, and the proposed impact of
physiological factors (feeding, respiration, metabolism)
on feed chain transport. Adapted from Thoiaann, 1981.
-------
SPECIFIC
CONSUMPTION
(cj/g d)
RESPIRATION
(d")
i-
U
AGE
TOXICANT
CONCENTRATION
III PHYTOPLANKTON
(/xg/g) (U
VN
\
Predt
ilion
TOXICANT
CONCENTRATION
IN ZOOPLANKTON
(/*g/g) (2)
:f;
Predc
t
ilicn
TOXICANT
CONCENTRATION ,
IN SMALL FISH '
(,ug/g) (3)
t
(I/
Predt
f
it ion
iS
| "AVAILABLE " (DISSOLVED) CHEMICAL WATER CONCENTRATION (/4g/L)
/
TOXICANT
CONCENTRATION
IN LARGE fid!
(/iQ/0) M)
x
PHYSICAL-CHEMICAL
MODEL Of
PARTICULATE AND DISSOLVED
CONCENTRATIONS
-------
65.
body mass of the subject organism. Pizza and O'Connor (1983) _ ...
demonstrated that most body compartments have ka and ke
vtlues sinilar to the "whole body". The cathenatics are straight-
forward, and based upon the exponential expression for a decay
curve:
M » MO« * (for absorption). (1)
where M is the quantity of PCB placed at the absorption site. M
is the quantity redlining at tine - t, and k is the absorption
rate constant.
Eliaination rate constants (k ) are derived from the same
expression with different notation:
where X is the whole body PCB level at tin* zero. X is the whole
body PCD burden at time t. and L is the eliaination rate con-
stant.
Values for PCD assimilation were deternined by force-feeding
striped bass known quantities of 14C-labeled PCB (Aroclor 1254) in
natural food, and sacpling at fixed intervals to determine: 1) the
quantity of PCD in the gut; 2) the quantities. of PCB in the whole
body; and 3) the quantities of PCB in feeal naterial. S«mpl ing of
fishes continued for a period of 120 hours. Tissues were analysed
-------
66.
for total C-PCB by liquid scintillation counting (Pizza. 1983).
Experiments were conducted to determine k »nd k from single
A 0
feeding and multiple feedings. Manipulation of the empirical data
conformed to treatnents suggested by Goldstein et al. (1974). The
equations are documented ia Table XI.
REStLTS
Vhen striped bass were given single doses of PCD, there
occurred initial and rapid elimination from the alimentary tract
followed by a phase of less rapid elimination (Fig. 8A). Whole
body elimination remained monophasic (Fig. 8B). Note that, after
48 hr, when alimentary tract burdens were < 10% of the dose, the
whole body burden was high, reflecting nearly complete assimila-
tion of PCB froo the natural food matrix. For a single PCS dose.
the body burden will follow a tine course reflective of the ratio
k /k , as shown in Fig. 9.
Fishes in contaminated environments, however, do not accumu-
late PCD as single, isolated dietary doses. Rather, they contain
PCBs derived from water uptake, and they receive multiple, sequen-
tial doses of PCB in food. Our multiple dose stcjy showed the
gradual approach to "plateau" FCB levels (Fig. K» expected for
young striped bass exposed to sequential doses of PCB in food.
given at 48 hr intervals. The interval was choien in order to
-------
67.
Table XI • Pharnacoklnetic expressions applied to PCS dietary uptake
studies.
A. Absorption rate (ka) M - M e~ a
B. Elimination rate (ke) X «• X0e~ket
C. Absorption half-tine tu tu - - "ln °'^
D. Fractional absorption-
single dose X/M0 - [e"ket/(kc/rka>_e-ket]/[(ke/ka).1]
E. Time to naxiauni absorption-
single aose (ka * ke) t^x = [2.3 loe(ka/ke)]/(ka-k€)
F. Maxitr.ua fraction absorbed-
single dose Xmax/Mo
C. Body burden at end of dosing
-k t* -k t* 2
interval - multiple doses X = Xoe e -4- Xo (e e ) +
H. Body burden after dosing-
multiple doses Xn
I. Plateau (steady state burden-
-k«t*
multiple dose
J. Fraction of plateau at "n"
, -ket*n
doses f - 1-e
-------
68.
Fig. 8 Experimental determination of PCS in striped bass after
force-feeding- A. Loss of PCB from the alimentary tract
shoving a two-phase elimination. Phase 1 describes assimi-
lation into the whole boJy. Phase 2 describes elimination
in parallel with other tissues. B. Whole-body elimination
of PC2. Note the similarity of slope vith Phase 2 of
alimentary tract elimination.
-------
95% C.I for KQ= 0.103! ±0.018! hr"
Phase 2
0
24
48 72
Time (hr.)
96
120
B.
IIOQ
0>
to
O
Q
o
Q-
95% CI for Ke = 0.0054+ 0.0008hr
-i
0
24 48 72 96 120
Time(hr.)
-------
69.
Fig. 9 The fractional absorption of a single dose Vv first-order
absorption and elimination. The solid curve was deter-
mined as in Table 4 and the data of the current study where
ke/ka = 0.05. A maximum of 85 percent was absorbed by
30 hr. The other curves are presented for comparison
(Goldstein et al., 1974) at tne same k<». The case where
ke/ka = 0 (ka = °°) is attained by constant input rate.
For kg/ka = 0.50, where for a ka smaller than that of the
solid curve, a lover •laxinu.u would be attained at a later
tine.
-------
1.0
o
CD
-------
70.
Fig. 10 Curve for the cumulative retention of PCB froa multiple
dosing. Solid lines present actual levels attained during
experiment. Dashed lines are the calculated extension
of the data. The plateau burden (Xo>) is the steady state
level attained froa peak values after sufficient dosing
(see text).
-------
O
CD
1600
•g 5200
{
I- 800
CD
O
O.
400
_ 90% X
J 1 1 1 1 i i t i i i
Timelhr.}0 48 96 144 192 240 288 336 384 432 480
Dose Number I 23456789 10 H
-------
71.
observe the approach to "steady-state". The feeding interval in
nature is note likely to be twice each day. Mathematically, this
is unimportant; what is essential is that the kinetics of the sys-
tem (see TableV-lI)show plateau reached at dose n = 17. or after 32
days.
APPLICATION TO MODELING
Thoaann (1981; see Fig. 7) documented clearly the complexity
required of models describing contaminant accumulation in fishes.
In his Bodel he noted: 1) ihe_lack of data relevant to the func-
tion referred to as the "food-chain multiplier"; acd 2) the aeed
to account for age-specific changes in respiration, feeding, and
growth as determinants of predicted PCB body burdens in striped
bass. In the preliminary model presented here we provide the food
chain multiplier, as influenced by growth of the fish, changes in
•etabolisn. changes in food ration, and changes in dietary PCB
levels.
Pizza's analysis (1983) of striped bass PCB accumulation from
diet revealed that changes in plateau PCB burden depended upon two
factors. The first is the k The second is the level at which new
o
PCB i* taken in via the food. The relationship between pcysiolog-
ical growth and required ration size, as well as weight-specific
•etabolisa, is depicted schematically in Fig. H along with the
expected effects that changes in these factors nay have on food
-------
72.
Fig-. 11. Schematic representation of the response of various
physiological parameters to increased size of the
organism. In the upper figure, required ration to grow and
respiration (vg 02 per hour per individual) increase with
increased size; assimilation efficiency of food decreases.
In the lower figure, metabolism and elimination constant
ke- decrease with increasing size.
-------
A
i T
c « i
O c: '
"—- o r-
O -r- c=-
.-= "5 .2
in
.^»
-*.
o
Size—>
A
i
t
i
to
Size
-------
73.
assimilation efficiency and the elimination constant (k ) for PCB»
(Califano et **... 1982; Pizza and O'Connor. 1983.- The physio-
logical data suggest that, for a growing fish, there should be no
steady-state PCE level, since metabolism (and, hence, k ) declines
with age, and since assimilation efficiency declines with increas-
ing age and ration required for growth increases, the PCB body
burden should increase continously. Further, since the volume of
water required for orygen exchange must increase with size, more
direct water uptake of PCB is possible. The iaportance of the
latter in contributing to body burden may be questioned, however,
since respiratory requirements may be extremely variable depending
upon ambient levels cf dissolved oxygen, teeperature, time of day.
tine in the feeding cycle, etc. (Neumann et al., 1982).
The phariaacokine tic jiodel incorporated these relationships
under conditions representative of striped b«ss biology in the
Endson estuary. These were:
1. Active fe-'diug during the first growing season on zoo-
plankton containing 1 jig/g (dry weight) PCB (O'Connor et
al.. 1982).
2. An instantaneous growth rate of 0.02 d""1 (O'Connor and
Bath, unpublished).-
-------
74.
3. Decreasing kg at a rate proportional to weight; W~°'3
(Brett. 1981).
4. . Increased ration size to maintain a daily intake of
body weight.
5. A feeding interval of 12 hr. with one-half the daily
ration (and PCE dose) consumed daring each feeding
period.
6. Additional feeding on zooplankton containing either O.S
t
H6/8. or 0.1 ug/g PCB (dry weight).
The aodcl was run under several input conditions for two sea-
sons of growth (total tiae 330 days). This exercise illustrates
the tenporal relationship of PCB input rite and output rate-
constant within the boundaries of a realistic time scale (Fig.'j).
Since the concentration in the diet was 1.0 ppn. the solid curve
shows the computed BAF. The initial rise in concentration (0-30
days) was the predicted plateau-shift. Once plateau was attained,
the typical asymptote did not occur, but rather the BAF skewed
upward as determined by the rate of decline in ke.
After one season of growth, the k declined to 0.0044 hr~
and the computed BAF w*s 0.76. This value is auch lower than the
l\f = 0.95 which would be calculated by simply dividing the feed-
ing rate by '.he k deternine-J tfter 5 months of growth (0.0044
-------
75.
Fig .12. Outcome of the pharnacok.inel.ic model describing dietary
PCS accumulation in striped bass. See text for details.
-------
18 r
16356
^ 08178
01036
30
60 90
-Seoson 1-
IZO J50 iBO 21C £40 270 300 330
H< Secson E *
Time
-------
76.
hr"1). The discrepancy i» explained by the fact that the BAF «
f
0.95 would be attained only with /.fficient time (- 44 days) and
cessation of the decline in k . allowing for the establishment of
« new steady state. This underscores the importance of recogniz-
ing that bioaccunulation is rarely characterized by steady state.
bnt rather is a process of uninterrupted plateau shift operating
as a continuum.
This point is illustrated by the dashed curves of Fig. 6.
For a diet containing 0.5 ppn PCB. the time required toe plateau-
shift was the sane as the 1.0 ppm situation, and the whole-body
concentration was one-half the level of the higher dosage. Divid-
ing the whole-body concentrations at any point in the curves by
the PCD concentration in the respective diet shows that the BAF is
the sane for the two situations.
The eore boldly dashed lines illustrated the expected outcome
of . change in input rate during growth. If the PCB concentration
in the diet is decreased, a piate*u-sbift will occur at a rate
determined by the declining ke. The whole-body concentration will
decrease, but since ke continue, its decliue with growth, the pla-
teau will eventually skew upward containing the irtegrity of the
BAF. This is demonstrated by dividing the whole-body concentra-
tion by tLat of the diet.
If the change i* to , note concentrated diet, the whole-bod.
-------
77.
harden should reach * higher level. The model predicts that an
increase to 1,0 ppm dietary PCD would cause a k -governed
plateau-shift to the whole-body level, attained from k continuous
1.0 ppa dietary exposure (Fig.IX, solid curve), once again main-
taining the BAF.
The growth rate in the model was determined by an assumed
instantaneous rate-constant of 0.02 d . This value was used
because it is consistent with the growth rate of juvenile Uudson
River striped bass, and results in approximately the same growth
observed in the field.
The model was run for consecutive growth intervals (seasons I
•od II). Fluctuations in growth known to occur due to pbotoperiod,
temperature, and other factors (Brett. 1979) were not considered.
Such perturbations should elicit a response consistent with the
k - and input-governed plateau shift.
A period of overwintering vras not included in the calcula-
tions because relatively little is known of Hudson River striped
bass physiological condition for this tine of. year. A reduction
in feeding rate would be exp-cted (BrUt. 1979) along with a
decline in metabolic rate (Neumann et al.. 1981). The decline in
body burden which is due to decrcajcd input should more than
Offset the increased burden owed to depressed k^. It is also
important to realize that toy reduction in kfi would cause an
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78.
increase in the tine required for shifting plateau. Overall, a
slow decline in body burden would be expected from overwintering
unless utilization of stored lipid accelerates the reduction.
Vhatever level the body burden attains during periods of reduced
metabolism, prediction based on growth would not change; once
plateau-shift is complete, the PCB concentration in the fish
should reflect the operant input rate and elimination rate con-
stant.
V/hen interpreted over a specific and realistic tine-franie
during life stages, the growth-re!a«ed DAF model suggests that the
PCD history of the fish nay be inconsequential (disregarding all
physiological perturbations) once a plateau-shift has occurred.
Rather than sinply interpreting field concentration data as the
end result of prior PCC exposure, it would be more informative to
use these data in fcioaccunulation prediction as determined by life
history witn corresponding feeding and clearance rates.
Data are available for young-of-the-yea. striped bass taken
in 197S iroa the Indian Point portion of the Hudson River (Cali-
fano et al.. 19S2; Jfehrle et al., 1982). Concentrations of PCB in
these two sanples vere 1.59 a=d 2.62 Mg/6 (»et wt). or about 6.4
and 10.4 pg/g (dry vt). respectively. O'Connor's (1982) data for
striped bass food organisas (Gannarus spp.) from the same portion
Of the Hudson averaged ~ 7 M/S <*ry wt) PCB. Given a BAF of 0.76
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79.
and a food source with 7 jig/g PCBs, one night expect a fish to
•
contain 5.3 ug/g PCB (dry wt) due to diet alone.
This calculation suggests that 51 to 83?» of the PCB in
striped bass is due to dietary uptake. It is not implied that
this night be the case for fishes in general; direct uptake from
vater is an important source of PCB to fishes, and cannot be
ignored. Uowever, the exercise does suggest that the dietary PCB
component nay 'je of great significance to fishes, especially in
heavily contaminated environments such as the Hudson estuary.
As stressed throughout this discussion, the feeding rate is a
critical factor in determining how much of the PCB burden was
acquired via the diet. The model operates under two assumptions
which concern the input rate and could affect the outcome of the
predicted body burden. The first assumption is that the dietary
PCB absorption efficiency is 100^. The current work with Aroclor
1254 showed that this level is not far from the efficiency
observed, and should suffice since it also serves to simplify the
model. For the limited data available, 51-83?o would constitute a
liberal assessment of the PCB burden obtained via the diet.
The second assumption involves the daily ration used in the
nodel. A daily requireDent c£ 10<5> body weight was chosen because
this level of feeding is cotnnon to many studies (e.g., Chesuey and
Este-e*. :976; Phillips andBuhler. 1978). This level is
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80.
arbitrary, however, since an insufficient amount of work has been
perforned on the relation of physiological condition and growth
rate to ration size. Conpouuuing this problem is the fact that
species, tenperature, and body size affect the growth/ration rela-
tion. The few available studies usually deal with salmonoids at
temperatures generally below 20°C (see Brett. 1979). and inference
to the ration required by Hudson River striped bass is difficult.
The sub-maximum growth rations reported by these studies are S'i or
less. For the current work, where striped bass received an amount
of fooo which filled the stor^ch without extension, a daily ration
of 5% would have been feasible when based on two feedings a day.
Laboratory striped bass of - 1 g (dry) can consume twice this
quantity of live G. t^grinus when fed passively at 12 hr intervals
(personal observation), and for the above reasons, a 101 daily
ration was used in the model. Once again, before verification of
the 51-83Si dietary contribution is possible, an accurate value for
ration is needed. It is also important to note that the BAF
values (Ki^. 6, solid curve) would be affected directly by the
required reduction or increase in ration.
Dietary accumulation is cost strongly influenced by feeding
and clearance rates. The decline of these rates as growth occurs
will detercine the ultimate dietary contribution to body burden in
mature fish. Certain environcenta1 factors, such as reduce' tem-
perature, couid serve to decrease ke and increase "BAF- due to a
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81.
depressive effect on cetabolic rates in striped bass and other
fishes (Neumann et al.. 1S31). The impact of the reduced kg under
low tenperatnre conditions, however, might be offset to'some
extent by simultaneous reduction in feeding during the winter
months, or by metabolic compensation to slowly changing environ-
nental conditions (Fry, 1971; Vetter, 1982).
The concept of growth-related plateau shift has application
to estimating body burdens in fishes exposed to varying conditions
of PCB input during different life-history stages. We kno-«. for
example, that when Uudson River striped bass migrate from riverine
nursery areas to the lower estuary and marine waters, they show a
significant reduction in PCD body burden (U'.S. 1980; MacLeod et
al., 1981; O'Connor et al., 1982). This reduction should be due
to redttced PCB input, since the PCB in both water and food in coa-
stal regions is less than in the estuary (Pierce et al.. 1981;
O'Connor et al.. 1982). With knowledge of the operant le.^ and the
PCE levels in food and water, the body burden and time for reach-
ing the new and lower level should be calculable. Research is
currently underway to obtain data appropriate to making such pred-
ictions.
Norstrom et al. (1976) discuss the environmental and growth
factors which influence contaminant accumulation through clearance
rate. All these factors require study. When the data become
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82.
available, they can add significantly to the accuracy of predic-
tive bioaccuaulat ion models for PCB and other contaminants (e.g.,
Thomann, 1981; Mackay. 1982). The data from tais study combined
with observations from the field suggest strongly that dietary PCB
sources are of great importance to striped bass. The combined
effect of efficient cross-gut assimilation of PCD and low k dic-
tates that PCD uptake from the food web be given additional atten-
tion in lexicological studies.
Oar empirical studies and modeling data have direct applica-
tion to ongoing ocean clumping studies as follows:
First, our hypothesis that PCB burden in fishes is strongly
related to diet renders the "mass loading" approach to ocean PCD
pollution ineffective in «sticating contaminant levels in fish.
Both dredged materials and sewage sludge must be evaluated more
carefully to assess real quantities of PCBs injected into the food
chain and the water column, rather than icrcly crtinating mass
loads placed in the ocean environment.
Second, the pharnacokinetics of PCCs in fishes suggests that
any isolation of contaaiuated materials from entry to the food
chain will have the effect of lowering PCB body burdens in the
large, predatory species which often form an important part of the
human diet. Thus, maintaining a surficial layer of sediments with
low or non-available PCCs will, in all likelihood, result in a
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83.
trend toward lower body burdens in all trophic levels.
Third, the overall outcome of the nodel suggests tLat w(
shall not see increased PCB levels in fishes if input rates and
input sources remain similar to those of recent years. Further
dumping regulations should include attention to rendering such
contaminants as PCB first, unavailable to food chains, and
finally, unavailable in the water column.
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84.
VITT. FIELD TEST ££ THE ECQKIKETIC HODEL FOR PCS ACCUMULATION JJJ FISHES
INTRODUCTICN
Previous sections in this report described laboratory studies
designed to quantify the mechanisms of FCB accumulation in striped bass
from water and from food sources. Our analyses of PCE kinetics and
assimilation from the diet suggested that PCB-contaminated food may be
the major source of body burdens in striped bass from the Hudson estuary
(Pizza and O'Connor, 1983; Section VII). An accumulating body of evi-
dence supports the thesis that chlorinated organics. and PCBs iu partic-
ular* are accumulated in fishes more from dietary sources than by
equilibrium partitioning frcn water (Mitchell et al.. 1977; Califano,
1980; Thcaann and Connolly. 1982; Pizza and O'Connor, 1983; Stehlik and
Merriner, 1983; ItcKira and He«th, 1983).
If this is true for striped bass in a PCB-contaminated environment,
and if the accumulation/elimination kinetics determined for PCBs in the
laboratory are valid in nature, then field-verification studies should
be possible (Pizza and O'Connor, 1983). The primary requirement would
be that the subject population occupy a habitat for a time long enough
to enable expression of shifts in plateau PCB levels. It would also
be essential that the PCB environment be "stable", and that PCB burdens
in food items or stomach contents be known.
This section presents the results of a field study conducted
between August. 1982 and April. 1983. During this tine samples of
striped bass, stomach contents and food items were taken frow various
sites in the Hudson estuary au
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85.
lected from January through torch were overwintering in the New York
Harbor region and* thus, represent a population liiaited in their move-
ments to a relatively small area. The fish collected from August 1982
through January 1983 included young-of-year striped bass; sampling sites
corresponded to nursery areas from August to October. 1982. and ycung-
of-year fish taken in January were overwintering in the liarbor area
(McLaren et al., 1981).
MATflltlALS AND METHODS
Collections of striped bass were made from July, 1982 through
April. 1983. The samples from July through October were taken using a
20 ra (50 ft) seine with 64 am mesh in the bag. Sampling sites were at
Stony Point and Croton Point, 11. Y., in the brackish water portion of the
Hudson estuary used as a nursery ground by young-of-year striped bass
(McLaren et al., 1981). The fish ranged in size froa 28 am to 57 no
(S,L.) during July, and from 66 to 86 na (S.L.) in October. The collec-
tions were transported alive to the laboratory where representative sam-
ples were removed and sacrificed for analysis.
The winter samples (January through March) were taken in the New
York Harbor region at Weehawken (January), Hoboken (March 2) and among
the piers at Canal St. in Manhattan (29 March)(Fig. 2). The collections
were made using a 12 a trawl with 1.3 taa stretch-mesh liner in the cod-
end. The fish taken during the winter period comprised several a&e-
classes, from 0+ (young-of-year) to 2+ (bass spawned in 1980). The
striped bass taken in trawls were placed in plastic bags and held on ice
in coolers for transport to the lab. They were sacrificed and processed
for analysis within 24 hr of collection.
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86.
Each fish for analysis was weighed and the standard length was
recorded. Stomachs were renoved and the contents (if any) were exanined
to identify the food organisms to genus and species (where possible).
Where stomach contents were of sufficient mass they were saved and
frozen for PCB analysis. In some instances, stomachs were either em^y.
or the contents were too few for PCB analysis; in such cases the prob-
able food items were inferred from other fish in the sjjaple and the
probable PCB content was inferred from the extensive data base we retain
on PCB distribution on Hudson River zooplankton (O'Connor. 1982).
Fish up to 86 inn (S.I~) were subjected to whole-body 2CB analysis.
Th2 fish were dried to constant weight at 50°C and ground in a mortar
and pestle; about 1 g (when available) was used for PCB extraction. For
larger fish (> 86 mm) a sample of epaxial muscle from the left side was
removed, weighed, dried, and pulverized, and portion (1 g) was used for
PCB extraction. Stonach contents and uningested food samples were
dried, weighed and pulverized prior to extraction.
PCB e. traction was carried out in acetonitrile (3>')» using a Bran-
sonic ultra-sound bath. The three extracts were combined and parti-
tioned to n-hexaae. followed by clean-up on florisil using 15% v/v ethyl
ether/hexane as the eluent. Samples were reduced in volume under a HZ
stream and analyzed on a Varian Kodel 3700 GC with a 16Ki ECD. The
coluan was a fused-silica capillary columr. with SE-54 as the stationary
phase. Quantitation of PC3s in individual peaks was performed by a
Sptrctra-Physics llodel 2000 integrator with parameters obtained from
analysis of U.S. EPA standard PCSs (Aroclor m4 and 1016). Isor.er
class identification was predicated upon analysis of selected chlorobi-
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87.
phenyl isonxers (Cl to Cl,)4
QA/QC data en PCB analyses was as follows: Recovery from spikes was
95%. n = 24; Procedure variation was ±. 8.3% based on sanple splits
prior to extraction; Instrument variation was 9.5% based upon repeat
analyses of single extracts* n - 12. Inter-lab comparison of unknowns
with U.S. EPA Gulf Breeze IGBERL) and with N.Y. State Dept. of Health
(DOH) labs yielded sirailar values at + 14."; (GBERL) and + 20% (DOE).
RESULTS AKD INTERPRETATION
1982 Year Class Striped Bass: Representatives of the 1982 year
claoS of Hudson River stripeJ bass were taken in saoples from July, 1982
through January* 1983. During this time the year clas- was growing
rapidly, increasing from a meon wet weight of 2.3 ± 0.8 (July 1932} to
20.7 ± 3.6 graas. Tliis rate of grcwth approxiuates <;he average fs-.wth
rate of 0.02 d for Hudson River striped bass as neasured by Dey et al.
(1981). PCB concentrations in the 1982 year class fish were highest
during July (10.8 +. 3.2 *ug/g dry weight) and lowest in the January, 19S3
sanple (1.5 ± 0.5 *ig/g dry).
ihe PCB concentrations decreased by a factor of 7.2 in the 160-day
period between 28 July and 4 January, while the size of the fish sampled
increased by a factor of 9. Total body burdens cf PCBs, in the July sta-
ples coupared to those taken i-> Januac>» J 983 showed an increase of
about 322. Thus, we conclude that while concentrations in the fish
decreased, the overall burdens in the fish did not; the data should not
be construed as evidence for sicple depuration of PCB associated with
titie.
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38.
We demonstrated in au earlier section that the rate constant for
PCB elimination (kg) was equal to 0.005 hr"** based upon ^C-Aroclor
1254 studies or whole-body PCB burdens. By applying the body burden
approcch to the present data it can be seen that there was. in fact* no
net loss of PCB during the specified tide interval. Rather, there
exists a sinilar burden or a slight iacrease in burden with tine. This
suggests that either PCBs are not being eliniaated in the environment,
or that the rate of PCE accumulation between July ana January is roughly
equal to the rate of elimination. The latter of the two hypotheses is
the core likely* since there exist measurable concentrations of PCBs in
Hudson River water and in striped bass food crganisas throughout the
Hudson system (O'Connor, 1982; O'Connor et al.. 1982; O'Connor and
Pizza, 1983; Section VII, this report). These data nay be used as a
test for the ecokinetic model (Section VII), using as input data the PCB
content of food at the upriver (Stony Point) station and the PCB content
of food items at the downriver (U'eehawken) station as well as estimated
rates of growth, feeding rates, basic pharcacokinetics (Section VI)
reduction in k associated with growth-related metabolic changes (Sec-
tion VII) and migratory movement of the striped bass.
The results of model runs predict that, during the first 150 days
of feeding, young-of-year stripes bass would accumulate 7.6 »ug/g PCB
due to diet if food organisms were assumed to contain 10 »ug/g PCBs. The
value for PC3 in food organisns is consistent with data collected for
food organisms in the Stony Point region (O'Connor, 1982), and results
in a food-related burden between 70 and 90* of the values observed at
Sto.iy Point and Croton Point in July, 19S2. In fact, the predicted
food-related body burdens are within one standard deviation of the
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89.
observed data.
Striped bass generally cove to downriver locations for overwinter-
ing (McLaren et al. , 1981). In January 1983* we ccasured PC3 values in
198Z year class fish at 1.5 *ig/g. These fish had available no then focd
organisms containing about A *ig/g PCBs. According to the ecokinctic
nodel. a change to food organisms containing lower levels of PCS would
result in a downward plateau shift. The nev plateau would be dependent
upon PCS dose, k and the dosing interval. Given a food concentration
of 4 *ig/g and assimilat ion/el initiation rates equivalent to those obtain-
ing at upriver sites, the predicted duration of the pl.-tcau shift would
be 25 days, with the uininua attained equal to 6.5 j-g/g PCB derived
from diet.
The predicted value of 6.5 *is/g nust be oodified. however, in oroer
to account for several factors. These ere: 1) reduced rate of feeding
during overwintering; 2) reduced growth rates during winter; and 3) gen-
erally lover metabolic levels during the overwintering period. Using
data fron Ueunann et al. (1931) which estia.ite the effect of temperature
on striped bass cetabolisn. we calculated that overall metabolic
activity of bass would decrease by a factor of approximately 3 concoiai-
tact with a 20 C reduction in tenperature (from 25 C to 5 C), Assuming
linearity in cetabolic systetas, this: would have the overall effect of
red-jcing both feeding rate and k by 3. In the nodel this would result
in a lengthening of the tine to plateau (fron 25 tc 75 days) and reduc-
ing the food intake by a factor 01 3. The outcone IE a predicted
miaiuvca body burden of 2.2 *Jg/g reached at 75 dij-s (uid-January) for
fishes ingesting food organisas at 4 ^/g at a reduced race. The calcu-
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90.
latcd burden is. in face, quite similar to that observed for 1982 year
class striped bass in the January sample.
These data suggest strongly that the ecckinetic model has a strong
predictive capacity. However, nany aspects of the nodel require refine-
ment and confirmation in order to provide body burden estimates th^t are
consistent with known physiological and behavioral parameters. Most
critical anong these are: 1) determining empirically lhat k declines
with growth; 2) determining the effect of reduced temper-ture on k and
feeding rate; 3) estimating the frequency ot feeding during winter
months; and 4) determining whether food conversion efficiency and the
PCB assimilation rate constant (k ) change with temperature.
Despite these required data, the field test of the model provided
support for a variety of important features pointed up by the model.
These are: 1) that PCB burdens in fishes are not fixed once accumulated,
since elimination processes appear to go on in nature, even under con-
taminated coalitions; 2) that estimates cf the dietary coaponent of PCB
burdens in fish appear Co be consistent at percentages generally above
751 of the total burdan; and 3) that the tiae course for dietary PCB
accumulation by fishas is a predictable quantity conforning to phar-
oacokioetic codeIs. This last point further supports the importance of
dietary uptake as the primary route for PCB accumulation, since the tiue
to plateau via diet vastly exceeds that calculated for uptake via the
water route.
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91,
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