United States
                     Environmental Protection
                     Agency
Municipal Environmental Research
Laboratory                         • 7 ,
Cincinnati OH 45268
                     Research and Development
EPA-600/S2-83-012  Apr. 1983
&ER&         Project  Summary
                     Effects  on  Cattle from  Exposure
                    to  Sewage  Sludge

                     J.C. Baxter, D. Johnson, W. D. Burge, E. Kienholz, and W.N. Cramer
                      This research was initiated to ex-
                     amine the effects of sewage sludge
                     disposal on agricultural land and the
                     potential for transmitting sludge con-
                     taminants into the food chain.  Soils,
                     forages, and cattle grazing on a sludge
                     disposal site were examined for trace
                     metals and persistent organics.  Cattle
                     were also fed diets containing digested
                     sludge to simulate worst-case condi-
                     tions of cattle grazing on sludge-fertil-
                     ized pastures.
                      Soils at the sludge disposal site had
                     increased concentrations on Zn, Cu,
                     Ni, Cd, and  Pb.  Forages from these
                     soils treated with sludge had higher
                     levels of Zn, Cd, Cu, and Ni and lower
                     Pb concentrations than forages from
                     soils that had not received sludge.
                      Cattle fed digested sewage sludge as
                     a percentage of their diet remained
                     healthy. The sludge had no positive or
                     negative effects on cattle performance
                     other than to act as a diet diluent.  The
                     direct ingestion of sewage sludge led
                     to  increased  levels of Cd and Pb in
                     kidney and liver tissues. The amount
                     of Cd increase was related to: (1) the
                     concentration of Cd in the diet; (2) the
                     Cd source (Fort Collins sludge versus
                     Metro Denver sludge), and (3) the time
                     period of sludge ingestion. Concentra-
                     tions of Cu, Pb. and Cd in liver tissues
                     were shown to increase in a linear
                     fashion during sludge ingestion. Cad-
                     mium did not decrease in liver or kidney
                     tissues when sludge was removed from
                     the diet; however, Cu and Pb in liver
                     decreased significantly.
                      Fat tissue from all sludge ingestion
                     studies showed significant increases
                     in Pea's DDE, dieldrin, and oxychlor-
                     dane.  DDE  and dieldrin decreased
                     significantly when sludge was removed
                     from the diet, but PCB's did not
  The effects to cattle from exposure
or ingestion of sewage sludge appear
benign.   Thus,  the  principal health
hazards associated with grazing cattle
on sludge-fertilized pastures would be
an increased level of  heavy metals
entering the human food chain through
kidney and liver consumption.
  Additional studies  were conducted
measuring the die-off rate of pathogens
in liquid sludge as the sludge dried in
earthen basins.  Analysis showed that
as the sludge dried, the number of fecal
coliforms, total coliforms, salmonellae,
f 2 and T7 bacteriophage, andAscaris
ova decreased  to low levels within
periods ranging from weeks to months.
  This Project Summary was developed
by EPA's Municipal Environmental Re-
search Laboratory. Cincinnati, OH,  to
announce key findings of the research
project that is fully documented in a
separate report of the same title (see
Project Report ordering information at
back).

 Introduction
  Although sewage sludge contains a
 number of valuable nutrients and humus
 materials that can be used to increase soil
fertility, problems are associated with the
 recycling of sewage sludge. Much of our
sewage is not only derived from garbage
or fecal material but is the product of an
 industrial society; thus, heavy metals and
 persistent organics, many of which are
 products or byproducts of industry, turn
 up in sludge. In addition to these elements
and compounds,  there is a disease po-
tential.   The problems associated with
 many of these elements, compounds, and
 biological agents become particularly acute
when they are potentially harmful to crops,
 animals, or the human food chain. The
 principal objective of this research was to

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examine cattle exposed to varying amounts
of sewage sludge to determine whether
and to what extent contamination of cattle
tissue had occurred as a result of sludge
exposure   To accomplish this objective
several separate, but interrelated,  studies
were conducted.
  The Metropolitan Denver Sewage Dis-
posal District No. 1 (Metro Denver) had
been recycling  sewage  sludge to land
since 1969. The sludge had been applied
to the  soil surface, plowed  under, and
planted to forages such as winter wheat
oats, sorghum, or sudan grass.  A herd of
beef cattle that had been on the sludge
recycling site since the inception of sludge
disposal there subsequently grazed these
forages. These cattle had been exposed to
sewage sludge for 6 years and had ample
opportunity  to  ingest contaminants  by
consuming sludge enriched forage or by
direct ingestion of  soil and sludge.  This
situation represented a unique opportunity
to examine  some  long-term  effects of
cattle exposure to sludge from a somewhat
typical ongoing practice.
  Soils, forages, and cattle from the sludge
disposal site (the abandoned Lowry Bombing
Range or LBR) were examined for heavy
metals and persistent organics. Disease
incidence, tissue heavy metal concentra-
tions, and persistent organics in fat tissues
from these cattle exposed to sludge were
compared with range cattle from a nearby
control ranch (no sludge exposure) and
with a larger group of cattle of known age
and no exposure to sludge.
   Kidney and liver tissues (tissues known
to accumulate heavy metals) from cattle of
known age and no exposure to sewage
sludge were also examined so that infor-
mation concerning normal background
concentrations- of these tissues could be
developed.  This  information  was then
compared with metal concentrations found
in tissues of cattle exposed to sludge.
  Additional feeding studies were designed
around the premise that the application of
sludge to soil or pasture land will result in
the direct ingestion of sludge constituents.
To assess the magnitude of  uptake of
heavy metals and persistent organics into
edible  and  other  tissues of cattle,  the
effects on cattle directly ingesting sludge
were examined
  Three sludge feeding studies were con-
ducted: (1) young feed-lot steers were fed
0%, 4%, or 12% Metro Denver sludge (20
ppm Cd) for 3 months; (2) young feed-lot
steers were fed 0% and 12%  Ft Collins
sludge (100 ppm  Cd) for 3 months;  (3)
older cows and young steers were main-
tained on 0% and 1 2% Ft Collins sludge
diets for 9 months, which was followed by
a 4-month withdrawal period in which no
sludge was fed. The quantities of sludge
were chosen to bracket likely ingestion
ranges including a worst-case situation.
Although cattle might ingest 12 % soil, the
likelihood that they would ingest 12 %
sludge is indeed remote.  Special  pains
were  taken to  feed a digested sludge
relatively high in cadmium concentration.
The objective was to have enough sludge
with enough cadmium to produce a measur-
able  uptake and then attempt  to  relate
uptake to health effects.
  This report also  describes work that
examined the time required for the destruc-
tion  of human pathogens.   Pathogens
such as enteric viruses, bacteria, protozoan
cysts, and helminth ova have been shown
to survive anaerobic digestion of sewage
sludges,  although the numbers of  these
organisms are usually greatly decreased if
not eliminated by this process.  Air drying
in beds and storage in stockpiles has the
potential to completely  eliminate  these
organisms. Anaerobically digested  liquid
sewage sludge was  placed  in earthen
drying basins.  The survival of endemic
saimonellae,  fecal  coliform,  inoculated
Ascaris ova,  and inoculated f2 and T7
bacteriophages were followed until  these
indicator organisms could no  longer be
detected.

 Results

 Heavy Metal  Levels in  Cattle
 Tissue
   Certain nonessential trace metals such
 as Cd and Pb have been shown to increase
in specific tissues (kidney, liver, and bone)
during the life span of animals.  Concentra-
tions of Fe, Zn, Cu, Cd, and Pb in kidney
and liver tissues of cattle not exposed to
sewage sludge were examined to augment
existing  information  concerning  normal
tissue levels of these trace metals in cattle
exposed  to different conditions.   These
cattle served as control animals  for  the
LBR tests.
  The  selected cattle had  known birth
dates and no previous exposure to sewage
sludge; the selection also provided a range
of dietary regimen, sex, and age. Animals
chosen for the study were:  4 beef cows
from the University of Wyoming; 25 range
beef cows from the same ranch in eastern
Colorado; 15 dairy cows from Colorado
State  University; and  12 young feed-lot
steers used as controls in sludge feeding
trials. The 29 range cows varied in age
from  5  to 15 years, the  steers  were
approximately 18  months old,  and  the
dairy cows ranged in age from 2 to 8 years
at the time of slaughter.
  Table 1 shows the mean concentrations
of Zn, Cu, Cd, Pb, and Fe in kidney and liver
tissues from the dairy and range cattle.
TheCu concentrations in liver tissues from
the dairy cattle were for the most part an
order of magnitude greater than those in
liver tissues from the range cattle.  The
large difference in liver Cu concentrations
was probably because  the  dairy cattle
received  dietary trace salt  supplements
added directly to their feed, whereas the
range cattle would not have received simi-
lar supplementa The significant difference
in kidney Cd concentrations between the
range cattle and dairy cattle was caused by
 Table 1.    Mean Concentration of Trace Metals Determined in Kidney and Liver Tissues from
           Control Cattle of Known Age
Tissue and
Element
Kidney:
Zn
Cu
Cd
Pb
Fe
Liver
Zn
Cu
Cd
Pb
Fe

fig/g (dry weight)
Range Cattle of Known Age

88.4
15.8
13.4
3.6
225

132
21.3
1.06
1.8
256

±
±
+
±
+

±
±
±
±
±

17.6*
3.2af
8.0a
1.7
73

25
32.3at
0.6
1.1
99

Dairy Cattle of Known Age

96
21.7
2.8
1.9
293

118
216
0.74
1.0
250

± 46
± 2.6 b
± 1.7b
± 1.3
± 64

± 26
+ 966
± 0.9
± 1.0
+ 72
 * Mean ± standard deviation.
 t Values followed by different letters are significantly different at the 1 % level using Student's t-
   test
 t If the 4 range cows from Wyoming are excluded from this analysis, the mean of the 25 Colorado
   range cows becomes 9.5 ±3.18 ftg/g Cu. The difference between range and dairy cattle is still
   significant

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a difference in age; the range-cattle age
averaged  10 years,  whereas the dairy-
cattle age averaged 4 years (Figure 1). The
range of Cd concentration was from 0.83
ppm in a 2-year-old dairy cow to 31.2 ppm
in a 13-year-old  range cow.   Levels of
other metals did not increase or decrease
in liver or kidney tissues with the age of the
animals.

Heavy Metals  and Persistent
Organics at the LBR Sludge
Disposal Site
  The heavy metal status of soils at the
LBR sludge  disposal  site showed that
concentrations of Zn, Cu, Ni, Cd, Pb, and
Hg were increased (Table 2), and concen-
trations of As, Se, Mo, and 22 organics
were unaffected by sludge amendment
Forage  crops grown on  these sludge-
amended soils  showed increased tissue
concentrations of Zn,  Cu, Cd, and Ni (Table
3); however, none of the metal concentra-
tions were elevated to a phytotoxic level or
to a range that would be considered ab-
normal for forage tissues. Concentrations
of As, Se, and Hg in  forage tissues were
unchanged, and  Pb  concentrations de-
creased as a result of sludge applications.
None of the forage tissues examined con-
tained detectable  levels of 22 persistent
organics.

Heavy Metal and Persistent
Organics Content of Cattle
Tissues from the LBR Sludge
Disposal Site
  Twelve older range  cows, which had
been on the LBR sludge disposal site since
the beginning of disposal operations, were
slaughtered and various tissues sampled
for heavy metals and persistent organics
analysis.  Heavy metal concentrations in
25
20
15
10

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2 4 6 S /O 12 14
Age (years)
Figure 1.   Mean concentration of Cd in
           kidney tissues (dry weight) as a
           function of cattle age. Numbers
           above bars represent number of
           animals for each group.  Tick
           marks represent standard devia-
           tion for each group.
kidney, liver, and muscle tissues were, for
the most part,  within a range  that  is
considered normal for older beef-type cows
(Table 4).  Muscle tissues, the primary
food tissue, contained levels of Cd and Pb
that were below detection limits.  The Cu
concentrations of liver tissues  were un-
expectedly low. These low liver Cu levels
indicated that dietary Cu levels must have
been  low; thus,  little sludge could have
been consumed by the cattle.
  Fat tissues were the only tissues to
show any detectable  levels of organic
residues. Detectable levels of alpha-BHC,
HCB, DDE, dieldrin, and PCB's were found
in both the sludge-exposed cattle  and
cattle from a nearby control ranch; however,
there  were no differences  between the
two groups that appear to be attributable
to sludge.
                                Cattle grazing the LBR sludge disposal
                              site were healthy and showed no greater
                              incidence of disease or death loss than
                              other herds in the area not exposed to
                              sludge.  Postmortem pathological examin-
                              ation of internal organs showed no signifi-
                              cant differences between the  LBR-site
                              cattle and a nearby control herd.

                              Effects of Sludge Ingestion by
                              Cattle
                                Three separate experiments were carried
                              out in which dried sewage sludge was fed
                              to cattle (as a percentage of their diet) to
                              simulate  worst-case conditions of cattle
                              grazing on sludge-fertilized pastures. All
                              of the cattle in these experiments remained
                              healthy throughout the  duration of the
                              experiments, and the sludge was shown
                              to have no negative or positive effects on
 Table 2.
Mean, Median, and Range of Heavy Metals in Surface Soil Samples from Areas of
Sludge Application and Control Areas Within LBR Site

                              IJtg/g (dry weight)
                    No Sludge Applications
                                         Areas of Sludge Application
Element
Zn
Cd
Cu
Ni
Pb
As
Se
Hg
Mean
50.8
0.43
10.6
11.8
18.2
<3
<1
<0.027
Range
39.5
0.18
6.75
6.0
14.0
<3
<1
0.010
-62.5
- 0.72
- 18.8
-43
-22.0
- 3
- 0.090
Median
93
1.45
11.0
21.8
36.2
3
1
0.150
Range
40
0.43
8.6
6.00
14.2
<3
<1
<0.010
-252
- 4.40
- 50.0
- 43.0
- 101
- 5
- 2
- 0.580
 Table 3.
 Element
Heavy Metal Concentrations of Forages from the LBR Site

                	         fig/g (dry weight)
           No Sludge Applications

                   Mean
                                                      Sludge Applied
Median
Range
   Zn
   Cd
   Cu
   Ni
   Pb
   As
   Se
   Hg
                  11.7
                   0.11
                   2.28
                  <0.57
                   2.3
                  <0.25
                  <0.35
                   0.024
75.8       37.2    - 153
 1.08       0.25  -   3.70
12.5        3.80  -  22.0
 2.80       0.25  -  15.5
 0.75      <0.65  -   4.0
<0.25      <0.2S
<0.25       0.25
 0.020      0.010 -   0.100
                                         Table 4.
           Mean Tissue Concentration of Control Range Cattle (Known Age) and Sludge Exposed
           Cattle at LBR Site
Tissue
Kidney:
Control (range)
LBR Site
Liver
Control (range)
LBR Site
Animals
Sampled
29
12
29
12
/jg/g (dry weight)
Cd
13.4a*
16a
1.1 a
0.8a
Cu
15.8a
16.1 a
9.5a
4.6b
Zn
88.4a
93a
132a
129a
Pb
3.6 a
0.8a
1.8a
0.3a
Fe
225
NDt
256
ND
* Values followed by different letters within a column are significantly different at the 1% level
 (Student's t-test).
fNot determined.

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cattle performance other than to act as a
diet diluent
  The first feeding study was conducted
with the use of young feed-lot steers that
were fed feed-lot rations containing 0%,
4%,  or 12%  (dry weight)  Metro Denver
sludge.   In the second feeding study,
similar steers were fed feed-lot rations
containing  0% or  12% (dry weight)  Ft
Collins sludge-sludge with Cd and  Cu
levels five times and two times, respectively,
that  of the Metro Denver sludge.  Other
metal concentrations were similar for the
two sludges  The duration of both feeding
studies was approximately 3 months.
Analysis of kidney and liver tissues revealed
significant increases of Cd and Pb because
of the increased dietary levels of  these
metals (Table 5). The estimated availability
or absorption and retention of Cd from the
sludges into the cattle tissues measured
0.07%  for the Ft. Collins sludge and
0.02% for the Metro Denver sludge. Not
all of the cattle tissues were analyzed  for
uptake of heavy metals; thus, total uptake
by all cattle tissues could  be higher, but
probably less than  1 % at best  Even a 1 %
uptake through consumption of sewage
sludge is significantly less than the 2% to
9% reported by other researchers utilizing
Cd salts and a variety of other animal
species; thus indicating that Cd uptake
from both sources  of sewage sludges
were less available for tissue uptake and/or
retention.    Muscle tissues showed  no
heavy increases due to the sludge ingestion
after this 3-month period.
  It  is known that young animals of most
species absorb greater percentages of
dietary heavy metals (particularly Pb) than
older animals, but the extent to which this
might occur in cattle had not been investi-
gated. The feeding trials described  herein
used young feed-lot steers; thus, the metal
uptake levels could have been higher in
select animal tissues  than would have
occurred with older animals. Another  as-
pect not examined in these studies was
the  possibility that some  portion  of  the
sludge-borne tissue contaminants could
be eliminated once the sludge was removed
from the cattle diet
  A third  sludge-feeding study was then
conducted. An older group of 16 Hereford
cows (3 to 7 years old) and a group of 16
Hereford steers (6 months old) were each
divided into two groups of eight each and
fed  maintenance diets consisting  of 0%
(controls) or 1 296  (dry weight)  Ft Collins
sewage sludge.  Thus, the 12% sludge
diet was fed to eight cows and eight steers
(two of the four treatment groups) for 9
months. At the end of the 9- month period.
four cows and  four steers from  each
treatment group were slaughtered.  The
remaining animals were kept on test for
another4 months, but sludge was removed
from the diet of those that had been fed
sludge.  All of the remaining animals were
then slaughtered at the conclusion of the
4-month sludge withdrawal period. Periodic
bone and liver biopsies taken over the 13-
month test period permitted a more detailed
investigation of uptake and depletion rates
of heavy metals in these tissues.
   Analyses of liver biopsies from the sludge
 fed cattle showed that Cd increased in liver
 tissues with time in a linear fashion (Figure
                               2). Cu and Pb also increased significantly,
                               but decreased when sludge was removed
                               from the diet (Figures 3 and 4).
                                 The ingested sludge resulted in signifi-
                               cant increases of Cd, Pb, and Zn in kidney
                               tissues (Table 6). Cadmium concentrations
                               did not decrease  after  the sludge  with-
                               drawal period, but Pb concentrations appear-
                               ed to have decreased slightly during the
                               withdrawal period
                                 Fat tissues were analyzed for 22 persis-
                               tent organics.  DDE and TNC increased
                               significantly in fat tissues due to the sludge
                               ingestion,  but  decreased  significantly
                               during the 4-month withdrawal  period.
Table 5.    Mean Cd Zn, Cu, and Pb of Ft Collins and Metro Denver Sludges and Tissue
           Concentration from Cattle Fed These Sludges
Tissue Types and %
                                 iig/g(dry weight)
Sludge in Diet
Ft Collins Sludge:
Kidney -0%
Kidney- 12%
Liver - 0%
Liver- 12%
Metro Denver Sludge:
Kidney - 0%
Kidney- 12%
Liver -0%
Liver- 12%
Cd
98
1.2 a*
14 b
0.1 9a
4.9 b
21
1.1 a
2.4b
0.2a
0.4b
Zn
1700
93a
96a
142a
132a
1500
84a
82a
87a
101b
Cu
1700
23a
21b
127 a
113a
710
17 a
15b
124a
240b
Pb
470
0.95a
11 b
0.31 a
4.3 b
780
0.9a
15.8b
0.2a
4.6b
* Means followed by different letters within a column and tissue type are significantly different at
  the 5% level (Student's t-test).
                    Sludge Fed Steers
                    y = 2.38X + 0.74
                    r = 0.999
   12'
5
                                                    O
                                                    X
                                        Sludge Fed Cows
                                        y =1.85x^0.75
                                        r = 0.98
                                             O
                                             X
                         Sludge
                         Feeding •
                         Period
                                                O  Sludge Fed Cows
                                                X  Sludge Fed Steers
                                                •  Control Cows
                                               A  Control Steers
                                   No Sludge
                                    in Diet
                                 6            9
                                     Months
                                                       11
                                                    13
 Figure 2.
Cadmium concentrations (dry weight) of liver biopsies during the 9-month sludge
ingestion period and 4-month withdrawal period.

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  400-1
Sludge Fed Steers
y-37.3x + 83
r = 0.52
                      Sludge Fed Cows
                      v = 17.8x^113.4
                                                    Sludge Fed Steers
                                                    Y = -62x + 547
                                                    r = 0.53
                                                     Sludge Fed Cows
                                                     y = -19x + 430
                                                     /• = 0.56
                                                     Control Cows


                                                     Control Steers
                          6         5
                            Months
11     13
                O Sludge Fed Cows
                X Sludge Fed Steers
                • Control Cows
                & Control Steers
Figure 3.    Copper concentrations (dry weight} of liver biopsies during the 9-month sludge
            ingestion period and 4-month withdrawal period.
               Sludge Fed Cows
               y - O.Sx + 1.98
               r = 0.87

                                                      Sludge Fed Steers
                                                      y = 0.35*+ 2.60
                                                      r = 0.69

                                                      Sludge Fed Cows
                                                      y = -1.2x + 17
                                                      r = 0.87
                                                      Sludge Fed Steers
                                                      y = -0.83x + 73.2
                                                      r = 0.73
                                                      Control Cows
                                                      Control Steers
— -A-



3

	 i 	


4
6 9
Months
\
	 -wV
e
•
A
;/ 13

                                                          O Sludge Fed Cows
                                                          X Sludge Fed Steers
                                                          • Control Cows
                                                          & Control Steers
Figure 4.    Lead concentrations (dry weight) of liver biopsies during the 9-month sludge
            ingestion period and 4-month withdrawal period.
which indicates that both compounds were
either metabolized or eliminated from fat
tissues.  Dieldrins, PCB's, HCB, and oxy-
chlordane all showed significant increases
because of sludge ingestion and decreased
after sludge withdrawal. These decreases
were not statistically significant however.
Trace levels of DDT, heptachlor epoxide,
and  chlordane were found in  most fat
samples analyzed but were not elevated
because of sludge ingestion.

Microbiological Studies of Air-
Dried Sludge
  The microbiological studies showed that
with adequate drying and residence time
in earthen drying beds, any enteric pathogens
remaining in the sludge  after anaerobic
digestion should be destroyed. The virus
indicator organism f2  had  a  maximum
survival time of  19 weeks even though
initial concentrations were orders of mag-
nitude in excess  of any enteroviruses.
Salmonellae and fecal coliform  bacteria
persisted for 70 and 73 weeks, respective-
ly, because of their ability for regrowth.
Sludge  desiccation may  have been the
most important factor  in bringing  about
the disappearance of these persistent or-
ganisms. Salmonellae were not detectable
after the  sludge had dropped  to  about
3096 moisture. Fecal coliforms were de-
tectable at less than 5% moisture,  but at
very low concentrations. Ascaris ova were
also sensitive to moisture. Only a small
portion of the inoculated  ova were  viable
when the sludge  moisture  content  had
dropped to 7.796.
  Storage of sludge for  a  year with  a
resulting decrease in sludge moisture to
1096 or less should reduce any pathogenic
organisms left after anaerobic digestion to
undetectable levels.  The likelihood of
pathogenic microorganisms moving from
the sludge into  the groundwater before
being inactivated is negligible.

Conclusions
  The effects on cattle from exposure or
ingestion of sewage sludge appear to be
benign.  The ingestion of high levels of
sewage sludge  by cattle will,  however,
raise heavy metal concentrations of a
number of  tissues  (mainly kidney  and
liver) and will also raise the  persistent
organics content of fat tissues.  The de-
gree of elevation, of course, is a function of
the amount of ingestion and concentration
of these substances in the  sludge.  The
data collected permit estimates of the
elevation to be made as a function of the
extent of ingestion.
  Muscle tissue, the principal food tissue
for man,  was effectively  screened from

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excessive accumulations of the contamin-
ants examined in this study.  The entry of
Cd and other heavy metals into the diet of
man would be largely through liver con-
sumption.  Although  high levels of Cd
were reached in liver and kidney tissues of
cattle consuming  Ft Collins  sludge for 9
months, this was  an extreme case and is
not likely to occur under normal agricul-
tural practices. It appears that cattle would
act as an effective screen against these
metals if sludges are properly used for the
fertilization of agricultural land.  Thus,  if
low metals sludges, such as the Metro
Denver sludge, are applied to calcareous
soils as a fertilizer and subsequently tilled
into the plow layer, there would appear to
be little potential hazard to the food chain.
  The full report was submitted in fulfill-
ment of contract No. 68-03-2210 by the
Metropolitan Denver Sewage  Disposal
District No. 1 underthesponsorshipofthe
U.S. Environmental Protection Agency and
the office of the Associate Director for
Physical  Science,  U.S.  Food and  Drug
Administration.
Table 6.   Heavy Metals Concentrations in Kidney Tissues of Cattle After 9 Months of Sludge
          Ingestion and a 4-Month Withdrawal Period
/jg/g (dry weight)
Treatment
Cows:
Control *
Sludge Fedf
Sludge Withdrawn §
Steers:
Control*
Sludge Fedf
Sludge Withdrawn §
Cd

7.4at
54.0b
69.0b

3.5a
57.06
64.0b
Pb

1.4a
4.3b
3.4b

1.1 a
5.2b
3.4b
Zn

77a
88b
131c

82a
98b
116c
Fe

320a
281 a
343a

255a
290a
247 a
Cu

17a
15a
17 a

19a
16a
16a
* Average of all control animals, 9-month and 4-month withdrawal period.
t Values within a group followed by different letters are significantly different at the 5% level using
 Student's t-test
t Cattle fed diet containing 12% sludge and slaughtered at 9 months.
§Cattle fed diet containing 12% sludge and slaughtered after 4-month withdrawal period.
   J. C. Baxter is with Metropolitan Denver Sewage Disposal District No. 1. Denver,
     CO 80229; D. Johnson andE. Kienholz are with Colorado State University. Fort
     Collins, CO 80705; W. D. Burge and W. N. Cramer are with the U. S, Department
     of Agriculture. Beltsville, MD 20705.
   Gerald Stern is the EPA Project Officer (see below).
   The complete report, entitled "Effects on Cattle from Exposure  to  Sewage
     Sludge," (Order No. PB 83-170 589; Cost: $16.00, subject to change) will be
     available only from:
           National Technical Information Service
           5285 Port Royal Road
           Springfield. VA 22161
           Telephone: 703-487-4650
   The EPA Project Officer can be contacted at:
           Municipal Environmental Research Laboratory
           U.S. Environmental Protection Agency
           Cincinnati, OH 45268
                                                                               U. S. GOVERNMENT PRINTING OFFICE: i!983/6S9-095/1924

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