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					Raccoons as Potential Vectors of Radionuclide Contamination to Human Food Chains from a
Nuclear Industrial Site
Author(s): Karen F. Gaines, Christine G. Lord, C. Shane Boring, I. Lehr Brisbin, Jr., Michael
Gochfeld, Joanna Burger
Source: The Journal of Wildlife Management, Vol. 64, No. 1 (Jan., 2000), pp. 199-208
Published by: Allen Press
Stable URL:
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         AS             OF
                           FROM NUCLEAR
KAREN GAINES,'      SavannahRiverEcologyLaboratory,   P.O. DrawerE, AikenSC 29802, USA
                                                  and              and
CHRISTINE LORD,Nelson BiologicalLaboratories Environmental Occupational
            G.                                                                      HealthSciences Institute,
             Piscataway,NJ 08855, USA
C. SHANEBORING,                                  and              and
                     Nelson BiologicalLaboratories Environmental Occupational       HealthSciences Institute,
             Piscataway,NJ 08855, USA and SavannahRiverEcologyLaboratory,
   University,                                                               P.O. DrawerE, AikenSC 29802, USA
i. LEHR BRISBIN, SavannahRiverEcologyLaboratory,
                  JR.,                                  P.O. DrawerE, AikenSC 29802, USA
MICHAEL    GOCHFELD,                 and
                       Environmental Occupational    HealthSciences Institute,                Piscataway,NJ 08855,
JOANNABURGER,Nelson BiologicalLaboratories                        and
                                                 and Environmental Occupational     HealthSciences Institute,
             Piscataway,NJ 08855, USA

Abstract: Although the raccoon (Procyon lotor) is commonly harvested and consumed throughout the south-
eastern United States, little is known regarding the fate and effects of environmental pollutants to this species,
and the potential for it to act as a contaminant vector to humans or other predators. Muscle and liver tissues
were collected from 76 raccoons from locations on and near the Department of Energy's Savannah River Site
(SRS) in South Carolina and analyzed for radiocesium (137Cs).Raccoons were trapped from areas near a former
reactor cooling reservoir known to be contaminated from former nuclear production activities, a stream drain-
age system also known to have received 137Cs contamination from low level releases, and 4 on-site reference
areas that have been unimpacted by nuclear production activities. Raccoons from 3 hunting areas 3-15 km of
SRS were used as off-site reference samples. 137Cs levels differed between the 3 treatment groups (contami-
nated, on-site reference, off-site reference) for both muscle and liver tissues. Muscle and liver samples from
raccoons from on-site reference areas were higher in 1'37Cs    than those from off-site reference animals. 137Cs
in raccoon tissues from contaminated habitats exceeded levels in the pooled reference animals. The 2 contam-
inated areas differed in 137Cstissue levels. Only 1 of 20 raccoons from contaminated sites on the SRS exceeded
the European Economic Community (EEC) limit for 137Cs in edible muscle tissue of 0.6 Bq 137Cs/g fresh-
weight edible muscle. Further, none of the raccoons from the on-site reference areas exceeded EEC limits
for muscle. It is unlikely that the hunting public faces any significant risk from exposure to raccoons from the
SRS. Although some raccoons might stray off the SRS which is closed to public access, most of the heavily
contaminated areas are not adjacent to the edges of the site, decreasing the potential for off-site movement
of contaminated animals.
                                                      JOURNALOF WILDLIFE        64(1):199-208

Key words: contaminant transport, Procyon lotor, radiocesium, raccoon, risk assessment, Savannah River Site,
South Carolina.

  Understanding the fate and effects of envi-              trial and aquatic food chains (Lotze and Ander-
ronmental pollutants is an important concern,              son 1979, Khan et al. 1995); (2) their ability and
particularly when wildlife may act as vectors of           proclivity to travel extended distances (Glueck
contamination to the food chain of humans or               et al. 1988, Walker and Sunquist 1997, Gehrt
other predators. The raccoon has seldom been               and Fritzell 1998); and (3) a propensity to uti-
considered in this regard, although it is com-             lize human-altered habitats in combination with
monly harvested and consumed throughout the                an ability to move freely in and out of toxic
southeastern United States (South Carolina De-             waste sites (Hoffmann and Gottschang 1977,
partment of Natural Resources 1996a,b). Sev-               Clark et al. 1989, Khan et al. 1995).
eral characteristics of raccoons make them po-                Numerous studies of the chemical cycling
tential agents of contaminant movement and                 and kinetics of 137Cshave provided insight into
                                                           its environmental behavior and potential biolog-
dispersal including: (1) a broadly omnivorous
diet which includes components of both terres-             ical uptake by game species (Brisbin 1991, Col-
                                                           well et al. 1996, Peters and Brisbin 1996). Ra-
                                                           diocesium has a moderately long physical half-
   1 E-mail:
                                  life (30.2 yr) and thus can persist for prolonged
200               IN       *
        RADIOCESIUM RACCOONS Gaines et al.                                           J. Wildl. Manage. 64(1):2000

periods in contaminated habitats. However, the                South Carolina

biological half-life of 137Csfor many species can
be considerably shorter. We found no studies
concerning the biological half-life of 137Cs in
raccoons. It has been documented that the bi-
ological half-life in the gray fox (Urocyon ciner-     Georgia
eoargenteus) is around 30 days, which compares
closely with that of the pig, both of which are
                                                                       0             Io

omnivorous species like the raccoon (Jenkins et
al. 1969). Further, it has been shown that spe-        LEGEND
cies having similar '37Cs biological half-lives         = Reservoirs
                                                        E SRS Delta
could have different 137Cs ecological half-lives       /V SRS RiverDrainage
                                                        0 UpperThree Runs
depending on characteristics of the contaminat-         0 Pond B
ed habitats (Brisbin 1991). Since 137Cs accu-           0 CarolinaBay
                                                        0 Ash Basins
mulates in edible muscle tissue (Narayanyan             0 Steel Creek
                                                        0 Beech Island
and Eapen 1971, Brisbin and Smith 1975, Pot-            0 Jackson
ter et al. 1989), it can enter the human food
                                                       o   CreekPlantation
                                                         R Former                reactor
chain when hunters near such sites consume                                 5   0     5     10 Kilometers
contaminated meat.
    Many radionuclide studies have focused on                                                 of
                                                       Fig. 1. Map of the U.S. Department Energy'sSavannah
                                                       RiverSite showingwetlandsand riverdrainagesystems. Cap-
highly mobile avian species because they can           ital letters ("R")indicatethe locationsof formernuclearpro-
rapidly transport accumulated radionuclides            ductionreactors,some of whichare knownto have served as
over long distances to the hunting public.             past sources of radiocesium  releases (see text).

Studying the potential for game mammals to ac-
cumulate 137Cs and serve as a direct vector to         nated stream floodplain. Our final objective was
the hunting public is warranted because of lim-        to estimate the relative health risks to humans
ited home ranges (e.g., vs. migratory game             from consumption of raccoons at observed
birds) and long-term exposure. To explore this,        137Cs levels in edible muscle tissue. This work
we examined 137Cs levels in muscle and liver           was part of a larger study on the part of the
tissues of raccoons inhabiting areas within and        Consortium for Risk Evaluation with Stakehold-
surrounding the SRS, a former nuclear produc-          er Participation (CRESP) and the Savannah
tion and research facility in South Carolina. We       River Ecology Laboratory to develop bioindi-
chose raccoons because of their potential to           cators of both human and ecological health.
serve as an indicator species for monitoring con-
taminant uptake and transport. Additionally, life      STUDYAREA
history of raccoons and other furbearers have             The SRS is a 778 km2 former nuclear pro-
been studied on the SRS since 1954, 2 years            duction and current research facility located in
 after closure of the site to public access (Kinard    west-central South Carolina (33.10N, 81.3?W;
 1964, Wood and Odum 1964, Jenkins et al.              Fig. 1) that was closed to public access in 1952.
 1969). Raccoons are commonly hunted in the            In 1972, the entire SRS was designated as the
vicinity of the SRS (Cothran et al. 1991) and          nation's first National Environmental Research
 may either be consumed by hunters or given            Park to provide tracts of land where the effects
 away or sold to the local public (South Carolina      of human impacts upon the environment could
 Department of Natural Resources 1996a)                be studied (Davis and Janacek 1997). Workman
    The first objective of this study was to com-      and McLeod (1990) provide a detailed descrip-
 pare the levels of 137Csin the liver and muscle       tion of the terrestrial and aquatic habitats of the
 of raccoons living in (1) sites known to be con-      SRS. Raccoons were collected from 6 locations
 taminated by '37Cs on the SRS, (2) SRS sites          on the SRS, 4 of which have not been directly
 that had no history of 137Cscontamination from        impacted by 137Cs-contamination from the SRS
 nuclear activities, and (3) habitats outside of the   (Fig. 1). Raccoons from SRS areas known to
 SRS boundaries. The second objective was to           have been directly contaminated by 137Cs re-
 compare 137Cslevels in raccoons residing in dif-      leases were collected from an 87-ha former re-
 ferent habitats on the SRS, to include a contam-      actor cooling reservoir (Pond B) and a disturbed
 inated reactor cooling reservoir and a contami-       stream flood plain (Steel Creek). Both of these
J. Wildl. Manage. 64(1):2000                        RADIOCESIUM RACCOONS * Gaines et al.
                                                              IN                                  201

systems have been intensely studied with regard     imately 15 km northwest of SRS (Beech Island),
to the bioaccumulation of 137Csin resident flora    and an area approximately 3 km from the south-
and fauna (Brisbin et al. 1974a,b; Evans et al.     ern SRS boundary (Creek Plantation). All 3
1983; Gladden et al. 1985; Brisbin et al. 1989;     hunting areas are part of the bottomland hard-
Whicker et al. 1990; Kennamer et al. 1993,          wood floodplain ecosystem of the Savannah Riv-
1998). Pond B received cooling water discharg-      er, which extends into the SRS along the site's
es from the SRS R-Reactor (shut down in 1964)       southwestern border.
that were contaminated with 137Csfrom leaking
reactor fuel elements. Peak introductions of        METHODS
137Cs occurred during 1963 and 1964 and             RaccoonTrapping Sampling
amounted to 5.7 x 1012 becquerels (Bq) of              Raccoons (n = 52) were collected on SRS
137Cs (Ashley and Zeigler 1980). The Steel          between December 1996 and June 1997 from
Creek watershed drains into an inundated riv-       2 137Cs-contaminated sites (n = 21) and 3 ref-
erine swamp delta that is contiguous to the Sa-     erence sites (n = 31). Raccoons were collected
vannah River. Two production reactors dis-          using baited traps (T. Fox, manufacturer, Bates-
charged effluents into Steel Creek containing       burg South Carolina, USA) set in the afternoon
cooling water mixed with purge water from ba-       and checked the following morning. Raccoons
sins used to store irradiated reactor fuel and      were transported to the laboratory, euthanized,
target assemblies. From 1954 through 1978, ap-      and dissected immediately. On the SRS we only
proximately 1.06 x 1013 Bq 137Cs that leaked        used male raccoons for this study to control for
from defective experimental fuel assemblies         possible variation due to sex and to prevent re-
were discharged into Steel Creek via this purge     moving pregnant females or females with young
water (Ashley and Zeigler 1980).                    from the population. Off-site reference rac-
   Two of the 4 sites on the SRS that were not      coons (n = 24) were collected during the state-
directly contaminated by plant operations           wide hunting season between January and Feb-
(hereafter "reference") were Carolina bays (Dry     ruary 1997 and frozen individually in labeled
Bay and Rainbow Bay; Fig. 1), which are nat-        plastic bags until dissection. Since it was not
ural elliptical depressions that vary in size and   possible to determine the sex of the raccoon
in the degree to which they retain water (Shar-     while hunting, females were included (n = 9).
itz and Gibbons 1982, Ross 1987). The third         These females were used within our analyses
reference site on the SRS was an undisturbed        because 137Cs levels in tissues from these rac-
natural stream flood plain system (Upper Three      coons were not different from the males col-
Runs-Tinker Creek area). Upper Three Runs           lected from the same sites (Wilcoxon 2-sample
Creek (UTR) has been used previously as a           test: Z = -1.68, P = 0.09). We removed livers
standard reference for comparing other upper        (10-20 g) and gastrocnemius muscles (10-20 g)
coastal plain stream areas of the southeastern      and froze tissues in scintillation vials for later
 United States. The fourth reference site on the    137Cs analyses. We followed an animal welfare
 SRS was a coal-fired power plant (D-Area ba-       protocol approved by the University of Georgia
sins), which discharges sluiced fly and bottom      Institutional Animal Care and Use Committee
ash into a series of open settling basins. Past     (A960205) and Rutgers University (97-017).
investigations of the D-Area basins, and nearby
 Beaver Dam Creek, have found enrichment of             Determinations
water, sediments, and biota with Al, As, Cd, Cr,       We determined 137Cscount rates of wet mus-
 Cu, Fe, Hg, Mn, Ni, Se, and Zn (Cherry and         cle and liver tissues using a Packard Auto-Gam-
 Gutherie 1977, Evans and Giesy 1978, Alberts       ma A5530 counting system (Packard Instru-
 et al. 1985, Sandhu et al. 1993, McCloskey and     ment, Meriden, Connecticut, USA) with a 7.62-
 Newman 1995, Rowe et al. 1996). However, no        cm thallium-activated Nal crystal of through-
 direct 137Cs contamination from SRS activities     hole design with a counting window of 550-760
 has occurred at this location.                     keV. Accuracy of the instrument was assessed
    Raccoons were also collected from nearby        by calibrating it prior to every counting se-
 public hunting grounds to serve as an off-site     quence using a certified calibration standard.
 reference group (Fig. 1). These sites included     Counting time per sample was 60 min for sam-
 an area located approximately 8 km west-north-     ples from contaminated areas and 500 min for
 west of SRS (Jackson), an area located approx-     samples from reference areas. Counting times
202               IN       *
        RADIOCESIUM RACCOONS Gaines et al.                                       J. Wildl. Manage. 64(1):2000

for each group were based upon preliminary an-
alyses of the sample count rate for all on-site
reference samples and sample masses, relative
to resultant minimal detectable concentrations
(MDC). To estimate tissue wet mass 137Cscon-        f    0.7

centrations (Bq/g), we first adjusted sample               O:                                              .
                                                                                            .. H... . .C.n.p ..L.n.(EEC)
gross count rates for background count rates.
We then compared the adjusted count rates of             .
samples to similarly adjusted count rates of
aqueous standards approximating the sample
geometry and containing known quantities of                                      SRSREFERENCE            OFF
137Cs. Background count rates were recorded
                                                               SRSCONTATED       REER~EINCE

following every third sample. This also provided                                          in
                                                    Fig. 2. Concentrations radiocesium raccoontissues col-
a measure to assure the precision of the instru-    lected between December1996 and June 1997 fromthe U.S.
ment over the analysis period. Count rates of       Department Energy'sSavannahRiverSite and offsitepublic
                                                    hunting               lines representranges,boxes represent
                                                            areas. Vertical
standards were determined daily for samples         25%-75% quartilelimits,and horizontallines indicatemedi-
counted for 60 min and twice a week for sam-        ans. For both muscle and liver, the SRS reference tissues
                                                    were significantlyhigherthan the off-sitetissues (P < 0.05).
ples run for 500 min. Standard count times cor-     Tissues fromthe contaminated were significantly
                                                                                   site                 different
responded to count times of samples to which        fromthe pooled (SRS and offsite)referencesites (P < 0.05).
they would be compared. The MDC's were cal-         The bold horizontalline represents the limitfor radiocesium
culated following procedures described by Cur-      contamination meatforhumanconsumption
                                                                   of                            (European  Eco-
                                                    nomicCommunity     1986), and numbersindicatesample sizes.
rie (1968).

          Analyses                                  roni corrections were performed when appro-
  We first examined 1'37Csdistributions using       priate.
Kolomogorov-D statistics (PROC UNIVARI-
ATE, v.6.12; SAS Institute 1988). Tests of hy-
potheses that these data were random samples               Those samples below their individual MDC
from normal distributions and tests of homo-            ranged from 0.01-0.10 Bq/g wet tissue mass for
geneity of variances were all rejected (P < 0.05)       this study. Radiocesium concentrations of all
even after efforts to transform the data failed.        off-site raccoon liver tissues and 96% of off-site
Therefore, we used Kruskal-Wallis tests (chi-           muscle tissues were below their respective
square approximation; PROC NPAR1WAY,                    MDC's. However, 58% of liver and 72% of mus-
v.6.12; SAS Institute 1988) to test for overall         cle tissues from on-site reference areas con-
differences among the 3 test groups (on-site            tained 137Cs levels above their MDC's. All liver
contaminated, on-site reference, and off-site           and muscle tissues from on-site contaminated
reference). Wilcoxon 2-Sample tests (Z approx-          areas contained 137Cslevels above their MDC's.
imation; PROC NPAR1WAY, v.6.12; SAS Insti-              Radiocesium levels differed among the 3 test
tute 1988) were used to determine significant           groups (contaminated, on-site reference, off-
differences between on-site and off-site refer-         site reference) for both muscle (Kruskal-Wallis
ence groups and for differences between areas           ANOVA: X22 = 43.90, P = 0.0001) and liver
affected by plant operations vs. all other areas.       (Kruskal-Wallis ANOVA: X22 = 44.81, P =
This test was also used to determine differences        0.0001; Fig. 2). Radiocesium levels differed be-
between habitats for the 2 on-site contaminated         tween on-site and off-site reference groups for
areas (Steel Creek vs. Pond B). Negative values         both muscle (Wilcoxon 2-sample test: Z =
for 137Cs concentrations occasionally resulted           -4.23, P = 0.0001) and liver (Wilcoxon 2-sam-
from sample count rates that were below back-           ple test, Z = -2.69, P = 0.0071; Fig. 2), with
ground. These negative and positive values              on-site reference areas showing higher levels of
which fell below their respective MDC's were            contamination in both tissues. Radiocesium lev-
not censored from the data analysis since to do         els were significantly higher in raccoons col-
so would bias the overall variance and could            lected from contaminated areas than those col-
bias the analysis (Gilbert and Kinnison 1981,           lected from pooled reference areas (on-site and
 Newman et al. 1989). All statistical tests were        off-site) for both muscle (Wilcoxon 2-sample
considered significant at P     0.05 and Bonfer-        test: Z = 6.36, P = 0.0001) and liver (Wilcoxon
                                                                IN       *
                                                      RADIOCESIUM RACCOONS Gaines et al.             203
J. Wildl. Manage. 64(1):2000

Table1. Concentrationsradiocesium wetmass)inraccoon
                    of          (Bq/g             tissuescollected       December andJune1997
                                                                   between       1996
from contaminated on theU.S.Department Energy's
                areas                 of       SavannahRiver Both
                                                             Site.          and   differed < 0.05)
                                                                       muscle liver      (P
between 2 contaminated
       the             areas.

                               Pond B                                    Steel Creek
 Tissue       n         i      Median       Range          n               Median         Range
Muscle        9      0.367     0.314    0.171-0.851        11    0.144     0.146       0.040-0.272
Liver        10      0.301     0.233    0.066-0.841        11    0.117     0.105       0.032-0.279

2-sample test, Z = 6.35, P = 0.0001; Fig. 2).        such as 137Csare prevalent in the soils and sub-
Finally, raccoons from the 2 contaminated areas      surface sediments on and around SRS (Strom
(Steel Creek and Pond B) differed in 137Cslev-       and Kaback 1992, Seaman et al. 1996). Further,
els for both muscle (Wilcoxon2-sample test, Z there is an inverse relationship between con-
= 3.34, P = 0.0008) and liver (Wilcoxon 2-sam- centration of available potassium in soil and up-
ple test, Z = 2.71, P = 0.0067; Table 1), with take of 137Cs (Nishita et al. 1960) since plants
Pond B being the highest in both cases.              growing in potassium-deficient soils take up the
                                                     available '37Cs as a potassium substitute (Has-
DISCUSSION                                           elow et al. 1989, Looney et al. 1990, Haselow
   Animalsinhabitingon-site areasthat received 1990). Soils from the on-site reference areas
direct contamination from SRS activities were where raccoons showed higher tissue 137Cscon-
an order of magnitude higher and showed high- centrations (e.g. UTR) were predominantly
er levels of variance in 137Cs than those from sandy and would tend to leach potassium and
the combined reference groups. Thus, raccoon be less likely to bind 137Cs cations. Conversely,
foraging habits and resource utilization may be areas with soils of higher organic matter and
sufficiently limited to allow them to reflect dif- high clay content (e.g., off-site areas such as
ferences in habitat contamination patterns at Jackson) may tend to bind cations such as 137Cs
these spatial scales. However, 137Cslevels in the especially if the clays are illitic in nature (Co-
on-site reference group were also significantly mans and Hockley 1991). This in turn would
higher than raccoons from the off-site reference     make 137Cs less bioavailable.
group.   This suggests that even in areas that have     Radiocesium differences in these reference
not been directly subjected to 137Cs releases,       raccoon populations may also be explained by
some SRS raccoons are still being exposed and home range size, with on-site raccoons possibly
accumulate more 137Cs than off-site popula- feeding on some occasions in contaminated ar-
tions. Seasonal differences in raccoon diets eas. Trap-recapture studies in the early 1960's
and-or overall fallout levels of 137Csover time on the SRS indicated that male raccoons trav-
might have contributed to differences in 137Cs eled 1.4 km between trap sites (Cunningham
levels between the 2 reference groups. Studies        1962), which would make it possible for SRS
on the SRS have shown seasonal differences            raccoons to reside within uncontaminated ref-
based on these factors (fall-winter vs. spring-       erence areas and yet still forage in some con-
summer) in white-tailed deer (Odocoileus vir- taminated areas.
ginianus; Rabon 1968) and in feral hogs (Sus             Because raccoons may move long distances
 Scrofa; Stribling  et al. 1986). Differences may (up to 4.3 km; Walker and Sunquist 1997), it is
also occurred because off-site raccoons were possible for raccoons to leave contaminated ar-
collected in late winter while on-site reference      eas and move to off-site areas using the flood-
 raccoons were collected late winter to early plain corridor. Raccoon tissues obtained from
 spring.                                              off-site locations were very low in 137Cs, sug-
    Differences in 137Cs between the 2 reference      gesting that sampled individuals from these
 groups may    also be due, at least in part, to the populations were not residing in 137Cs-contam-
 nature of the geology and associated soil types inated areas on the SRS. The risk of transport
between on-site and off-site foraging areas (Ta- of 137Cs from the SRS to off-site locations by
 ble 2). Soils with higher clay content may tend raccoons would probably be higher for raccoons
 to bind available 137Cs, depending on mineral- inhabiting the Savannah River floodplain system
 ogy, thus making it less bioavailable. Such clays than for those associated with the contaminated
 with a high affinity for poorly hydrated cations reservoirs, since the former represent large con-
Table 2. Concentration radiocesium(Bq/g wet mass) in raccoon muscle tissue collected fromreference locationson the U.S. Department
                      of                                                                                                         o
publichuntingareas near the SRS. Physiographic                and
                                             province(Workman McLoed1990), general soil types, and theirdescriptions(Rogers 1

         Location                 n   Median   Minimum   Maximum       province              General soil type

On-site reference
 Upper Three Runs Creek          12   0.053      0.011   0.123     Sandhill          Blanton-Lakebed Association Somewhat
                                                                                                                   are sandy
                                                                                     Troup-Pickney--Lucy Associ- Well draine
                                                                                       ation                       have a sa
                                                                                                                   some are
  Carolina Bays                   6   0.050      0.074   0.018     Upper coastal     Blanton-Lakebed Association See above.
                                                                                     Fuquay-Blanton-Dothan      As-   Well draine
                                                                                       sociation                        soils that
                                                                                     Rembert-Hornsville Associa-      Poorly drai
                                                                                       tion                             that have
 D-area Ash Basin                13   0.019      0       0.058     Upper Coastal     Rembert-Hornsville Associa-      See above.
                                                                     Plain             tion
                                                                                     Chastain-Tawcaw-Shellbluff       Poorly drai
                                                                                       Association                      drained s
                                                                                                                        and are
Off-site reference
 Beech Island                     8   0.005    -0.040    0.037     Upper Coastal     Shellbluff-Chewacla-Johnston     Well draine
                                                                     Plain                                              poorly dr
                                                                                                                        loamy th
 Jackson                         14   0.005    -0.014    0.037     Upper Coastal     Bethera-Ogeechee-Angie           Poorly drai
                                                                     Plain                                              soils that
 Creek Plantation                 2   0.011      0.010   0.012     Upper Coastal     Blanton-Fuquay--Lakeland         Nearly leve
                                                                     Plain             Associations                     a sandy s
                                                                IN      * Gaines et al.
                                                       RADIOCESIUMRACCOONS                          205
J. Wildl. Manage.64(1):2000

tiguous areas of suitable habitat that lead off-       sumption pattern and the median 137Cslevel in
site.                                                  the raccoon muscle (0.182 Bq 137Cs/g) from
    Raccoon tissues from the Pond B reservoir          contaminated sites, a hunter could consume no
area contained significantly higher 137Cs con-         more than 18 meals of SRS raccoon meat per
centrations than those from the Steel Creek            year (or 6.43 kg of meat per year), without ex-
Delta-Savannah River floodplain area. Our data         ceeding the U.S. Food and Drug Administra-
suggest that 137Csmay be more bioavailable to          tion's and U.S. Environmental Protection Agen-
raccoons in the Pond B reservoir system than           cy's most conservative action level of a 1 x 10-6
the Steel Creek floodplain of SRS, even though         excess lifetime cancer risk (Rodricks 1992; see
the latter originally received larger inputs of this   Kennamer et al. 1998 for calculations). Further,
contaminant (Ashley and Zeigler 1980). This            muscle of only 1 of 20 raccoons from contami-
finding is consistent with previous studies ex-        nated sites on the SRS exceeded the EEC limit
amining 137Cs in wood duck (Aix sponsa) eggs           of 0.60 Bq 137Cs/g (EEC 1986) and no muscle
from the same 2 areas (Kennamer et al. 1993,           samples of raccoons from the reference areas
 1995). The longer retention of the original 137Cs     on SRS or off-site exceeded the EEC limit.
released to Pond B vs. that to Steel Creek (Bris-          Public hunting is allowed on the Crackerneck
bin 1991), together with the seasonal remobili-        Wildlife Management Area (WMA) adjacent to
zation of 137Csfrom sediments to the water col-        the SRS, but access is limited to only 30 days a
 umn in the hypolimnion in Pond B (Alberts et          year, during the daylight hours (Sanchez and
 al. 1979, 1987; Whicker et al. 1990), could ac-       Burger 1998). Most hunters use Crackerneck
 count for its longer persistence in the biota of      WMA for white-tailed deer, and not raccoons
 the Pond B area.                                      because night hunting is not allowed. Although
                                                        some raccoons might move off SRS, most of the
MANAGEMENT                                              heavily contaminated areas are not adjacent to
    Raccoons are trapped for their fur and hunt-        the borders of the site or in the Savannah River
ed for both sport and food in South Carolina.           swamp, with the exception of the Steel Creek
Raccoons accounted for 20% of the state's total         delta, thus limiting the potential for off-site
1995-96 commercial fur harvest (South Caro-             movement of contaminated animals. Thus, as
lina Department of Natural Resources 1996a).            long as public access for the hunting of raccoons
Raccoon hunting is a growing sport, among               is restricted from the on-site contaminated ar-
both young and experienced hunters, with par-           eas sampled in this study, it is unlikely that the
ticipation in raccoon field trials nearly doubling      consumption of 137Cs-contaminated meat pre-
in the last 10 years (South Carolina Department         sents any meaningful health concern for the
of Natural Resources 1996b). Despite the in-            hunting public in the vicinity of SRS. Further,
crease in sport hunting for raccoons, there are         long-term studies on SRS addressing issues of
few data on the consumption of this species by          ecological half-life in several game species have
the public. In South Carolina, the raccoon hunt-        indicated that there have been long-term de-
ing season is usually from mid-September to             creases in 137Cs body burdens as this isotope
mid-March, with no bag or possession limit.              undergoes physical decay (Brisbin 1991, Brisbin
Thus, a diligent hunter who enjoyed the sport            and Kennamer 2000). However, these studies
 of raccoon hunting and ate the meat could le-           have also shown that disturbances can further
 gally consume as much raccoon meat as desired.          remobilize this contaminant, thus increasing its
A survey of attendees at a sportsmen's exposi-           bioavailability and making it difficult to model
 tion in Columbia, South Carolina in 1998 re-            its effective ecological half-life.
 vealed that nearly 10% of those interviewed said           The consumption of contaminated raccoon
 they ate raccoon, with an average serving size          meat would be only 1 possible route of human
 equivalent to 350 g (J. Burger, unpublished             exposure. Any comprehensive risk assessment
 data). Those who ate raccoon averaged only 1            should also include estimates of the risk from
 meal per year, with a maximum of 12 meals per           other contaminants in all hunted species. Such
 year. It is likely however that few people in low-      a comprehensive risk estimate should also esti-
 er economic strata attended this event, and             mate external exposure to gamma radiation
 therefore subsistence hunters who might con-            from contaminated sediments and particulate
 sume raccoons more frequently may have been             inhalation while hunting or otherwise residing
 underrepresented. Based on the above con-               within contaminated areas (Whicker et al.
206                         *
         RADIOCESIUM RACCOONS Gaines et al.
                   IN                                                         J. Wildl. Manage. 64(1):2000

1993). Although the different forms of contam-             S. K. WOODS. 1974a. Patterns of radiocesium in
inants may vary by species and between sites,              the sediments of a stream channel contaminated
studies as reported here can serve as a model              by production reactor effluents. Health Physics
                                                           27: 19-27.
for ways in which data for contaminant burdens                , D. D. BRESHEARS, L. BROWN,M. LADD,
can be used to provide general estimates of the            M. H. SMITH, M. W. SMITH, AND A. L. TOWNS.
health risks that would be associated with the             1989. Relationships between levels of radioces-
                                                           ium in components of terrestrial and aquatic food
consumpti"n of game by the hunting public.                 webs of a contaminated streambed and floodplain
                                                           community. Journal of Applied Ecology 26:173-
ACKNOWLEDGMENTS                                            182.
                                                                 AND R. A. KENNAMER.2000. Long-term
  We thankW. L. Stephens, Jr.for contributing                 ,
                                                           studies of radionuclide contamination of migra-
to the experimental design of this study and for
                                                           tory waterfowl at the Savannah River Site: impli-
his expertise and contribution in the field. Com-          cations for habitat management and nuclear
ments by E. L. Peters, R. A. Kennamer, Buddy               waste site. Studies in Avian Biology 1999: In
Baker, B. D. Goldstein, C. Powers, T. E. Phil-             press.
                                                              , AND M. H. SMITH. 1975. Radiocesium con-
lippi, J. M. Novak, and 2 anonymous reviewers              centrations in whole-body homogenates and sev-
helped improve the manuscript. We also ac-                 eral body compartments of naturally contaminat-
knowledge J. M. Novak for his statistical con-             ed white-tailed deer. Pages 542-556 in J. B. Gen-
sultation. We thank C. S. Romanek and J. C.                try and M. H. Smith, editors. Mineral cycling in
Seaman for advice concerning geology and soil              southeastern ecosystems. National Technical In-
                                                           formation Service, Springfield, Virginia, USA.
geochemistry. This project was funded through                   M. A. STATON, E. PINDER, III, AND R. A.
Financial Assistance Award DE-FC09-96SR185464              GEIGER. 1974b. Radiocesium concentrations of
from the U.S. Department of Energy to the                  snakes from contaminated and non-contaminated
                                                           habitats of the AEC Savannah River Plant. Cop-
University of Georgia Research Foundation and              eia 1974:501-506.
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