EPA-650/2-75-049
June 1975 Environmental Protection Technology Series
CADMIUM IN THE ENVIRONMENT - III
A TOXICOLOGICAL AND EPIDEMIOLOGICAL APPRAISAL
U.S. Environmental Protection Agency
Office of Research and Development
Washington, D. C. 20460
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EPA-650/2-75-049
CADMIUM IN THE ENVIRONMENT - III
A TOXICOLOGICAL AND EPIDEMIOLOGICAL APPRAISAL
by
Lars Friberg, Tord Kjellstrom,
Gunnar Nordberg and Magnus Piscator ,,
The Karolinska Institute
Stockholm 60, Sweden
Contract No. 68-02-1210
ROAP No. 26AAA-066
Program Element No. 1AA001
EPA Project Officer: Robert J. M. Horton, M.D,
Special Studies Staff
National Environmental Research Center
Research Triangle Park, N. C. 27711
Prepared for
U.S. ENVIRONMENTAL PROTECTION AGENCY
OFFICE OF RESEARCH AND DEVELOPMENT
WASHINGTON, D.C. 20460
June 1975
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EPA REVIEW NOTICE
This report has been reviewed by the National Environmental Research
Center - Research Triangle Park. Office of Research and Development,
EPA, and approved for publication. Approval does not signify that the
contents necessarily reflect the views and policies.of the Environmental
Protection Agency, nor does mention of trade names or commercial
products constitute endorsement or recommendation for use.
RESEARCH REPORTING SERIES
Research reports of the Office of Research and Development, U.S. Environ-
mental Protection Agency, have been grouped into series. These broad
categories were established to facilitate further development and applica-
tion of environmental technology. Elimination of traditional grouping was
consciously planned to foster technology transfer and maximum interface
in related fields. These series are:
1. ENVIRONMENTAL HEALTH EFFECTS RESEARCH
2. ENVIRONMENTAL PROTECTION TECHNOLOGY
3. ECOLOGICAL RESEARCH
4. ENVIRONMENTAL MONITORING
5. SOCIOECONOMIC ENVIRONMENTAL STUDIES
6. SCIENTIFIC AND TECHNICAL ASSESSMENT REPORTS
9. MISCELLANEOUS
This report has been assigned to the ENVIRONMENTAL PROTECTION
TECHNOLOGY series. This series describes research performed to
develop and demonstrate instrumentation, equipment and methodology
to repair or prevent environmental degradation from point and non-
point sources of pollution. This work provides the new or improved
technology required for the control and treatment of pollution sources
to meet environmental quality standards.
This document is available to the public for sale through the National
Technical Information Service, Springfield, Virginia 22161.
Publication No. EPA-650/2-75-049
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TABLE OF CONTENTS
Page
CHAPTER 1 INTRODUCTION 1-1
CHAPTER 2 PROBLEMS OF ANALYSIS 2-1
2.1 ANALYSIS OF FOODSTUFFS 2-2
2.2 ANALYSIS OF URINE 2-5
2.3 ANALYSIS OF ORGANS 2-7
2.4 ANALYSIS OF BLOOD . 2-8
2.5 ANALYSIS OF AIR 2-12
2.6 ANALYSIS OF WATER 2-14
2.7 CONCLUSIONS . 2-15
Tables
Figures
CHAPTER 3 OCCURRENCE, POSSIBLE ROUTES OF EXPOSURE
AND DAILY INTAKE 3-1
3.1 OCCURRENCE AND POSSIBLE ROUTES OF EXPOSURE 3-1
3.1.1 Cadmium in air - occurrence and sources 3-1
3.1.2 Cadmium in soil and uptake by plants 3-3
3.1.3 Cadmium in food 3-8
3.1.4 Cadmium in cigarettes 3-12
3.1.5 Changes in cadmium concentrations in
food over time 3-13
3.2 PRESENT DAILY INTAKE OF CADMIUM 3-14
3.3 CONCLUSIONS 3-15
Tables
Figures
CHAPTER 4 METABOLISM 4-1
4.1 UPTAKE AND ABSORPTION 4-1
4.1.1 Respiratory deposition, clearance, and
absorption 4-1
4.1.2 Gastrointestinal absorption 4-2
4.1.2.1 Gastrointestinal absorption in animals 4-2
4.1.2.2 In human beings 4-6
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4.1.3 Placental transfer 4-7
4.1.4 Conclusions 4-8
4.2 TRANSPORT, DISTRIBUTION AND EXCRETION OF
CADMIUM IN ANIMALS 4-8
4.2.1 Uptake to and clearance from blood 4-8
4.2.2 Tissue distribution and retention 4-9
4.2.3 Excretion 4-13
4.2.3.1 Via urine 4-13
4.2.3.2 Via bile, pancreas, and gastrointestinal
tract 4-15
4.2.4 Biological half-time 4-16
4.2.5 Interactions between cadmium and other
metals or compounds 4-17
4.2.6 Conclusions 4-23
4.3 TRANSPORT" DISTRIBUTION AND EXCRETION OF CADMIUM
IN "NORMAL" AND EXPOSED HUMAN BEINGS 4-24
4.3.1 Transport and distribution in blood 4-24
4.3.2 In organs 4-25
4.3.3 Excretion 4-28
4.3.3.1 Via urine 4-28
4.3.3.2 Via other routes 4-29
4.3.4 Conclusions 4-31
4.4 METALLOTHIONEIN: OCCURRENCE AND PROPERTIES
Tables
Figures
CHAPTER 5 EFFECTS 5-1
5.1 RESPIRATORY, RENAL, LIVER AND BONE EFFECTS 5-3
5.1.1 Studies on animals 5-3
5.1.1.1 Acute exposure 5-3
5.1.1.2 Prolonged exposure 5-3
5.1.2 Studies on highly exposed groups 5-9
5.1.3 Studies on populations in Japanese cadmium-
exposed areas 5-14
5.1.4 Etiology of Itai-Itai disease 5-18
5.2 EFFECTS ON CALCIUM- AND VITAMIN D-METABOLISM 5-22
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5.3 EFFECTS ON THE CARDIOVASCULAR SYSTEM 5-26
5.4 EFFECTS ON THE TESTICLES 5-28
5.5 TERATOGENIC EFFECTS 5-33
5.6 ACUTE SYSTEMIC EFFECTS OF CADMIUM INJECTION -
STUDIES IN RELATION TO CHRONIC EFFECTS AND THE
POSSIBLE INFLUENCE OF METALLOTHIONEIN 5-38
5.7 CARCINOGENIC AND GENETIC EFFECTS 5-47
5.7.1 Carcinogenic effects 5-47
5.7.2 Genetic effects 5-48
5.8 OTHER EFFECTS 5-49
Tables
Figures
REFERENCES R-l
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CHAPTER 1. INTRODUCTION
This volume constitutes the third report on cadmium written
under contract No. 68-02-1210 between the U.S. Environmental
Protection Agency and the Department of Environmental Hygiene
of the Karolinska Institute, Sweden. Previous data are avail-
able in the two earlier reports and in a monograph published
by the Chemical Rubber Company Press and entitled Cadmium
in the Environment, 2nd edition, 1974 (in this report abbre-
viated as CITE, 2nd ed.).
Since we received the first contract to compile and evaluate
data on cadmium, an upsurge of interest, research and
publication about this metal has been witnessed. Several
reviews have appeared, those of Flick, Kraybill, and Dimitroff,
1971; Riihimaki, 1972; Fulkerson et al., 1973; and Fleischer
et al., 1974, to name just a few. In addition, the Oak Ridge
National Laboratories have put out an extensive annotated
bibliography entitled Cadmium in the Environment and edited
by Emily Copenhaver et al. A health criteria document on cadmium
is currently under preparation at WHO.
Like the previous reviews, the present work focuses upon
information essential to the understanding of the toxic
action of cadmium and the relationship between exposure and
effects on human beings and animals.
Through repeated personal contact with several Japanese
researchers, it has been possible to obtain and evaluate
much data from Japan which would not have been accessible
otherwise. Several articles in Japanese were translated
through resources provided by the Project Officer. Non-
translated articles in the Japanese language could be
taken into account as well since Dr. Kjellstrom speaks
and reads Japanese. We express our gratitude for invaluable
assistance from different Japanese researchers and agencies.
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CHAPTER 2. PROBLEMS OF ANALYSIS
In CITE, 2nd ed., it was concluded that several methods may
be used for the determination of cadmium in biological ma-
terial, such as food, urine, organs, blood, etc. The most
commonly used method was reported to be atomic absorption
spectrophotometry, but interferences from especially NaCl
may give erroneously high results. Extraction techniques
or background correction techniques could limit the problems
of interferences.
The great lack of strict methodological studies and of com-
parisons of analyses of the same material between different
laboratories was pointed out. In the chapters about occurrence
and metabolism of cadmium in CITE, 2nd ed., the difficulties
in comparing data from different countries, when the accuracy
of the methods is uncertain, were discussed.
Because of the different composition of various biological
materials no standardized methodology suitable for all mate-:
rials has been developed. Especially at the low concentrations
of cadmium, occurring in for instance urine and blood of non-
exposed persons, considerable problems still remain as regards
finding suitable methods for cadmium analysis.
Shults, Lyon and Carter, 1973, compiled the available infor-
mation about different methods for cadmium analysis, making
a rough calculation of the sensitivity and accuracy of each
method. The performance of the methods is to a large extent
dependent on the chemical preparation of the samples before
final analysis and therefore their figures should be con-
sidered approximate and dependent on the type of material
analyzed.
In CITE, 2nd ed., the problems of analysis were discussed
method by method, but in this report we have chosen to
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present the new data in relation to the type of material
analyzed instead.
2.1 ANALYSIS OF FOODSTUFFS
Childs and Gaffke, 1974, investigated the interferences of
different elements with measurement of lead and cadmium in
fish muscle. Interfering solutions of 14 different elements
were prepared at the concentrations regularly found in fish
muscle. Such solutions were added to standard solutions of
cadmium and these mixtures were analyzed with flame atomic
absorption either directly or after extraction with MIBK.
Interferences were regularly less than 10% at a cadmium con-
centration of 0.1 yg/g in water solution, but some elements
(Al, P, Na) decreased cadmium measurements with more than
10% and some (Ba, Zn, Cl) increased the measurement with
more than 10% after MIBK extraction.
Gajan et al., 1973, described a standard method.for determi-
nation of cadmium in food, which was adopted by the Associa-
tion of Official Analytical Chemists (AOAC). The method,
involving wet ashing and extraction in dithizone/chloroform
followed by atomic absorption, had been tested in a collabor-
ative study. Detailed instructions for this method were dis-
tributed to 10 different laboratories, each of which first
practiced on samples with known cadmium concentrations.
Unknown samples of various foodstuffs spiked with 0.05 yg/g
or more were subsequently distributed and analyzed by each
laboratory. In this way the recovery of the different labor-
atories could be calculated, turning out to be between 83
and 116% for each material.and spiking level. The average
results on duplicate unspiked samples of lettuce ranged
from 0.02-0.04 yg Cd/g, for sugar from 0.00-0.05 yg/g and for
wheat from 0.01-0.1 yg/g.
A chelating ion exchange resin has been used by Baetz and
Kenner, 1974, for the separation of cadmium from food
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samples digested with HNO , H SO. and HO. Cadmium is ana-
•J ^ ™t ^ fc
lyzed with atomic absorption spectrophotometry without back-
ground correction. This method was demonstrated to be com-
parable with the method by Gajan et al., 1973, mentioned
above, both methods giving about 90-100% recovery after spiking
with 0.4 or 0.3 yg Cd/g. For original foods on the other
hand the detection limit was 0.01 \ig Cd/g. In several mate-
rials, as for instance sugar, beans and rice cadmium was
not detectable. At this low level the agreement was not good,
and it is doubtful whether the conclusion, that the ion ex-
change resin method allows determination down to 10 ng Cd/g,
is valid.
A pulse polarographic technique for analysis of cadmium in
dried milk has been developed by Cornell and Pallansch, 1973.
10 g samples of milk powder were dry ashed at 500 C overnight
and the ash was dissolved in diluted nitric acid. The solution
was analyzed in a polarographic analyzer using a hanging mer-
cury drop electrode. Cornell and Pallansch tested different
ashing temperatures and nitration of ash during ashing and
found that at 470°C and lower the recovery was 5-10% lower
than at 500 C. This could be improved by nitration of the
ash during the ashing procedure. It was believed that carbon
particles caused a decrease in the recovery. When the tempe-
rature during ashing was raised to 600 C the recovery also
decreased, probably due to volatilization of cadmium.
When the dry milk samples were spiked with 2 ng Cd/g and 10
ng Cd/g, recovery at the lower level was about 86% and at
the higher level about 95%. The natural concentration of
cadmium in dried skim milk was about 2 ng/g. In dried cow
milk the authors found 0.7-2.9 ng Cd/g in 18 individual
determinations, the relative standard deviation being 28%.
The useful lower analytical limit for routine analysis of
milk powder is claimed to be 0.5 ng Cd/g, corresponding to
about 0.05 ng Cd/g wet weight in fluid milk. The authors noted
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that the procedure developed for milk should be applied to
other material with caution.
Lee, Kim and Park, 1973, described a method for simultaneous
neutron activation analysis of mercury, bromide, arsenic and
cadmium in biological samples. The cadmium method is similar
to earlier reported methods for neutron activation analysis.
In a standard kale powder with an earlier reported average
cadmium concentration of 0.74 tfg/g, the authors reported
0.50^0.05 yg Cd/g, but left this difference without discus-
sion. On 3 rice samples from Korea they reported 0.02±0.002,
0.075*0.004 and 0.10*0.007 yg Cd/g. These results are in the
same range as reported cadmium concentrations in rice from
non-polluted areas in Japan (CITE, 2nd ed.) .
Krinitz and Franco, 1973, suggested a standard method for
determination of cadmium and lead extracted from glazed cera-
mic surfaces, and compared results from 13 different labora-
tories when they used this method. The method is adapted from
the German standard procedure, and involves leaching of the
metals into 4% acetic acid at 22°C for 24 hours. The leaching
solutions are analyzed with flame atomic absorption spectro-
photometry. In leaching solutions with an average of 1.01 yg
Cd/ml the relative standard deviation among the 13 laboratories
was 3.9%. Most of the paper deals with leaching of lead, and
the evaluation of the performance of the method on cadmium
containing samples is not extensive. This method was adopted
by the AOAC.
Kjellstrom et al., 1974a, compared the results of cadmium ana-
lysis in wheat from 7 different laboratories, each laboratory
using its own method. The samples, all unspiked, ranged from
about 10 to about 115 ng Cd/g. The analysis was performed on
a completely blind basis. There was a good agreement between
neutron activation analysis, sparked source mass spectrometry,
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isotope dilution and atomic absorption spectrophotometry after
high temperature dry ashing or wet ashing. On the other hand
atomic absorption without background correction and emission
spectroscopy gave considerably higher values (Table 2:1).
2.2 ANALYSIS OF URINE
Recently the heated graphite atomizer (HGA) and the carbon
rod atomizer (CRA) have been introduced as tools to increase
sensitivity in atomic absorption spectrophotometry. Kubasik
and Volosin, 1973, have developed a method for the simulta-
neous extraction of lead, cadmium and thallium from urine with
a combination of sodium diethyldithiocarbamate and methyl-
isobutylketone (DDTC/MIBK). 1.6 microliters of extracted
metal solution were introduced into the carbon rod atomizer.
With an addition of 5 yg cadmium per liter urine, the reco-
very was 90-104% in 10 samples. The authors showed that the
standard curves for unextracted aqueous standards and extrac-
ted urine standards differed in such a way that the urine
standards of cadmium were about 30% lower. Some constituents
in the urine matrix affected the sensitivity of the standard
curve, whereupon the authors suggested that standard additions
for preparation of the standard curve are needed for accurate
analyses. A hydrogen lamp was used for background correction
and after extraction the authors reported that the non-atomic
absorption accounted for about 0.5 yg cadmium per liter. When
urine was injected directly into the carbon rod atomizer the
results were unsatisfactory because of the great non-atomic
absorption. The coefficient of variation in 20 determinations
on a urine pool was 4% (average cadmium concentration 6.15 yg
per liter). In 13 samples of unspiked normal urines, the
average was 1.7 yg cadmium per liter (range 0-4.1 yg cadmium
per liter). Kubasik and Volosin did not discuss the possibi-
lity of a larger coefficient of variation at this low cadmium
level.
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Kubasik and Volosin, 1973, also studied the effect of addi-
tion of various elements to the urine before extraction,
showing that a fivefold increase in chloride concentration of
urine gave 122% recovery of cadmium and a fivefold increase in
phosphate concentration gave 84% recovery of cadmium as com-
pared to a 96-103% recovery of cadmium when 7 other elements
were added.
Interlaboratory comparisons of cadmium analyses in urine have
recently been performed. Hoschek and Schittke, 1973, reported
on a study in which a number of German research institutes
received similar subsamples of 10 urine samples for analysis
of lead and cadmium. The samples were prepared from a mixture
of urine to which cadmium from 10 yg per liter to 1,000 yg per
liter had been added. Only the data from one institute regar-
ding cadmium, for which the dithizone method was utilized, are
presented in the report. It is seen that the agreement between
expected cadmium concentrations and found cadmium concentration
was very good in the range of 10 yg per liter to 1,000 yg per
liter.
KjellstrSm et al., 1974a, compared cadmium analyses performed
in 3 Japanese and 1 Swedish laboratory on urine samples (range
1-28 yg/1) using neutron activation analyses and atomic absorp-
tion spectrophotometry with different modifications of the
preparatory steps. As seen in Figure 2:1 the agreement between
neutron activation analyses and the different atomic absorp-
tion methods was good. One of the APDC/MIBK extraction methods
used at the Swedish laboratory gave somewhat lower values than
the other methods. The low level samples were a mixture of
normal Swedish urines and the high level samples were either
spiked with cadmium standard or mixtures of urine from cadmium
workers.
Shiroishi et al., to be published, made another interlabo-
ratory comparison of cadmium analyses. The participants were
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one of the Japanese laboratories which contributed to the
study by Kjellstrom et al., 1974a (using AAS after DDTC/MIBK
extraction) and the same Swedish laboratory (using.AAS after
APDC/MIBK extraction). The analyses were performed on a blind
basis. There was no difference in the average results, the
correlation coefficient between the results from the labora-
tories being 0.99.
Harada, Taniguchi and Sato, 1974, studied the cadmium con-
centration in urine from 117 persons living in a cadmium
polluted area. 50 ml of urine was wet ashed with nitric
acid and perchloric acid and afterwards extracted with
APDC/MIBK. Cadmium concentration was analyzed with atomic
absorption spectrophotometry with and without deuterium
background correction. The average uncorrected cadmium
concentration was 13.53 yg;per liter and the average cor-
rected concentration 6.52 yg per liter. It is surprising
that such a difference in these values would be re-
ceived after APDC/MIBK extraction. Harada, Taniguchi and
Sato, 1974, also analyzed 15 of the urine samples with
atomic absorption after dithizone/chloroform extraction.
On an average the dithizone/chloroform technique gave
about 10% lower values than APDC/MIBK without correction.
2.3 ANALYSIS OF ORGANS
In adult human beings or in exposed animals the cadmium con-
centrations in organs like lung, liver and kidney are usually
so high (Chapter 4) that several existing methods may be con-
sidered reliable. Two new approaches in this field will be
reported here. Kaplan, Blackstone and Richdale, 1973, have
modified the chemical preparation of lung samples before
atomic absorption. They digest dried lung samples in tetra-
methylammoniumhydroxide in toluene at 60 C for 24 hours after
which they analyze the toluene solution directly with flame
atomic absorption spectrophotometry. In the description at
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hand, 0.25-gram samples of rat lung tissue were analyzed,
giving a coefficient of variation of between 2 and 25% at
cadmium levels between 0.3 and 6 yg/g (3 determinations).
The method was not compared with any other method, hindering
the evaluation of the advantages of this type of sample pre-
paration.
Another new approach in cadmium analysis is neutron activation
analysis in vivo where a neutron flux from a lithium target
is directed to a part of a living person (Biggin et al., 1974).
The neutron flux is given in pulses of 15 microseconds. During
half an hour the person receives a dose of 1 rem. The neutrons
are captured by the stable isotope Cd (12.3% abundance),
followed by emission of a cascade of gamma rays where the
strongest energy is at 559 keV.
In a study on phantoms Biggin et al. found that the detection
limit of the method would be around 2 yg/g for the liver.
However, the authors reported that in a study on a cadaver,
they could only ascertain the presence of cadmium in the
region of the liver. No specific.concentration could be
calculated. It is thus still uncertain as to whether this in
vivo neutron activation analysis can be developed into a
feasible method for cadmium analyses.
2.4 ANALYSIS OF BLOOD
In CITE, 2nd ed., it was concluded that analysis of cadmium
content in blood poses considerable problems and that the true
average blood concentration among non-exposed persons is not
known but can be assumed to be around 1 ng/g or less. For expo-
sed persons spectrographic methods have been used and the
practical detection limit was around 4 ng/g. As with urine
(section 2.2) the matrix effects when analyzing blood may be
considerable.
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A method which has been given considerable interest during
recent years is the "Delves cup" technique applied to atomic
absorption spectrophotometry. The Delves cup technique involves
introducing a micro-crucible made of nickel into the flame of
the atomic absorption spectrophotometer and in this micro-
crucible, 10 yl aliquots of blood are introduced and atomiza-
tion of blood cadmium achieved. The method was primarily deve-
loped for blood lead analysis (Delves, 1970). In order to
avoid the matrix effects when analyzing cadmium in blood
with the Delves cup technique, Lieberman, 1973, extracted
cadmium from hemolyzed, heparinized whole blood with APDC/MIBK.
This direct extraction of cadmium from blood has also been
used by Westerlund-Helmerson, 1970, in combination with reg-
ular flame atomic absorption and then the detection limit
was claimed to be 2 ng Cd/g blood. Lieberman, 1973, used
4 ml samples of whole blood and by adding cadmium chloride
equivalent to concentrations varying between 5-100 ng Cd/ml
blood, he found the apparent sensitivity of the technique
to be approximately 1 ng/ml. On the other hand in triplicate
analysis of the sample with 5 ng Cd/ml added the range in
absorbance was 0.022-0.038 indicating that at low cadmium
levels the reproducibility of the method is rather poor.
With added cadmium concentrations equivalent to 50-100 ng
Cd/ml the author found the recovery to be close to 100% for
both urine, plasma and whole blood. As the cadmium additions
in the study were equivalent to cadmium concentrations 5-100
times higher than the expected values in non-exposed persons,
it is hard to draw conclusions about the validity and pre-
cision of this method at lower levels.
Cernik, 1973, put 20 yl whole blood samples into nickel micro-
crucibles (Delves cup), dried the samples at 100°C for one
minute and then oxidized the dried blood samples by heating
them on a hot-plate at 425°C for 5-6 minutes. When the micro-
crucibles were subsequently put into the flame, a single peak
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could be received on the recorder corresponding to the cadmium
atomization. Background absorption, checked at 220 run with a
lead lamp, never accounted for more than 3%. Internal stan-
dards were used. By adding cadmium to blood corresponding to
20 ng/g it could be shown that the losses of cadmium in the
drying and oxidation steps varied between 6 and 10%. By adding
cadmium corresponding to 25 ng Cd/ml at repeated analysis the
standard deviation was about 2 ng Cd/ml and the absolute sensi-
tivity of the method 23 picogram cadmium (corresponding to 1.15
ng Cd/g blood). In this case as well, the method was not tested
on the low cadmium levels actually found in "normal" samples.
A problem with the Delves cup is that its repeated insertion
and removal from the holders may give rise to small distor-
tions in the shape of the micro-crucibles which seriously
affect the precision of the method (Joselow and Singh, 1973).
A good precision even after 200 analyses can be achieved by not
removing the cups from the holder between burn offs .
Another problem with the technique is the precision needed as
regards the distance from cup to flame in the initial combus-
tion phase and position of the cup in relation to the absorption
tube (Ulander and Axelson, 1974). These authors developed a
mechanical device with which the position of the micro-crucible
could be reproduced with precision (Ulander, personal communi-
cation) . Whole blood was placed into the micro-crucibles without
extraction and in 25 repeated analyses of blood samples with
addition of 1, 3, 10 and 20 ng Cd/g as well as without addi-
tion it could be shown that the mean blood concentration without
addition was 1.4 ng/g with a coefficient of variation of 16%.
The range was 1.1-1.8 ng Cd/g (n = 25). With increasing cadmium
additions the coefficient of variation decreased and with an
addition equivalent to 20 ng Cd/g the average cadmium concentra-
tion found was 21.4 ng Cd/g with a coefficient of variation of
6.3% (n = 25). The data indicate that the Delves cup technique
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performed in the way described by Ulander and Axelson, 1974,
can also give reproducible results at the low cadmium concentra-
tions normally found in non-exposed populations. The problems
are nonetheless considerable and Delves, 1974, himself reported
that it was not possible for him to separate the cadmium absorp-
tion signals from those of the combustion products of the sample
when using the Delves cup technique, because of the relatively
low vapor pressure of cadmium and its salts. Further research
on the methodology of the Delves cup technique is needed in
order to develop a reproducible and dependable standard proce-
dure. !
Stoeppler et al., 1974, used the flameless atomic absorption
technique for analyzing cadmium in water-hemolyzed whole blood
without extraction. The average in 37 samples was 9.5 ng/g
(range: 4-19 ng Cd/g). The authors themselves believed this
value to be rather high but could not find an explanation.
Deuterium background correction was applied. The problems in-
volved in blood cadmium analysis are underlined by results of
an interlaboratory comparative study on analysis of the same
samples (Berlin et al., 1974). Three blood samples were sent
to 14, 17 and 17 different laboratories respectively. The range
in the average results reported from each laboratory was 1-92,
0.3-73, and 0-110 ng/g for the three blood samples.
One aspect of blood cadmium analysis that is sometimes ignored
is the contamination of metals from syringes and blood con-
tainers during sampling. Taylor and Marks, 1973, filled diffe-
rent containers with distilled water and left them for 48 hours
at room temperature. In some of the containers up to 400 ng
zinc per gram was found in the distilled water after the experi-
ment and up to 100 ng magnesium/g. Syringes and pistons of
syringes were tested by putting them in 10 ml of distilled
water for 30 minutes at 75 C. Metal concentrations found in
the water after the experiment were up to 2,000 ng zinc/g,
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up to 430 ng copper/g, and up to 560 ng magnesium/g. As it
can be assumed that together with zinc contamination, cadmium
contamination may also occur to a certain extent, the data
indicate the necessity of checking equipment for metal conta-
mination.
2.5 ANALYSIS OF AIR
Another material which is important to analyze in health
effect studies is air, both ambient and workplace. It is not
the aim of this report to go into detail concerning all the
problems regarding analysis of air related to the length and
interval between sampling times, locations of sampling sites,
procedure for dust collection and the chemical analysis of
cadmium in collected dust. The general aspects of air analysis
have been treated in a recent review by Linch, 1974.
Some details worth mentioning are that Natusch, Wallace and
Evans, 1974, found a preferential concentration of some heavy
metals in small-sized fractions of dust in air. Both regarding
cadmium and several other elements the concentration increased
when the particle size decreased. The authors offered one expla-
nation as being that the elements volatize in the high-tempera-
ture combustion in emitting-industries and then recondense
preferentially or are adsorbed preferentially onto the large
available surface area per unit mass provided by the small par-
ticles. The authors conclude that the highest concentrations
of toxic elements are emitted in the smallest, lung-depositing
particles and that particle collection devices should be designed
for collecting the smallest particles. They also concluded that
the estimates of toxic element emissions based on analyses of
samples from existing particle precipitators would grossly under-
estimate the actual emissions.
MacLeod and Lee, 1973, investigated a method for trace metal
determination of spot-tape samples (AlSI-method) of ambient
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air. Anodic stripping voltanunetry after low-temperature ashing
of cut-outs of tape from the automatic tape sampler was employed.
The problem with this methodology was that the blanks (spot
sampler tapes without dust) contained 44-116 ng Cd. Because of
the large variation of cadmium amount in the blanks and the
size itself of this amount, the practical lower level for cad-
mium analysis would be around 500-1,000 ng/sample. As these
samples contained only about 60% of the dust collected, the
total necessary cadmium amount in collected dust would be
around l.Svg. In order to analyze cadmium concentrations down
to 1 ng/m more than 1,000 m of air has to be sampled in one
filter. Colovos, Wilson and Moyers, 1973, also applied anodic
stripping voltanunetry analysis of cadmium in dust collected
on millipore filters. Low temperature ashing was utilized. The
millipore filter contains less cadmium in the blanks; the
authors claimed that the practical sensitivity of the method
was 10 ng Cd/filter which means that at least 10 m of air
must be sampled in order to detect 1 ng Cd/m'.
Kneip et al., 1973, suggested a dithizone/chloroform extrac-
tion method combined with light spectrophotometry for analysis
of air samples. The authors stated that in order to analyze
10 ng Cd/m an air-sample volume of 200 m would be appropriate.
In cases in which very limited air volumes can be sampled the
method by Brodie and Matousek, 1974, may be the most suitable.
Air dust is collected on millipore filters, the filters having
been washed in hydrochloric acid and distilled water prior to
use in order to reduce the blank. A cut-out of the filter is
inserted directly into a carbon-rod atomizer and treated
therein with 2 pi of phosphoric acid (1,000 yg/g). Cadmium
phosphate has a relatively high boiling point and the atomi-
zation comes somewhat later than for other cadmium compounds,
hence enabling a better separation of non-atomic absorption
and cadmium absorption in the recorder. The atomic absorption
spectrophotometer used by Brodie and Matousek was only single
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2-14
beam and therefore deuterium background correction could not
be applied. Very limited data are presented in the paper,
but the authors claim that the absolute sensitivity of the
method would be 1.5 picogram cadmium, which corresponds
to an air concentration of 8 ng Cd/m in an air volume of 0.2
liters! Further research into this analytical method would be
of great interest;
2.6 ANALYSIS OF WATER
Rbjahn, 1972, analyzed estuarine water from the Oslofjord
by anodic stripping alternating current voltammetry. Five
similar samples gave an average cadmium concentration of 0.19
yg Cd/liter (variation coefficient = 21%) and the average of
a duplicate analysis of a similar sample using atomic absorp-
tion spectrophotometry was 0.12 yg Cd/liter. Prior, to anodic
stripping voltammetry, the samples had been filtered through
a 0.45 ym membrane filter. Atomic absorption was performed
after extraction. The data show the relatively large diffe-
rences that may be obtained even in such relatively uncompli-
cated samples as water.
Olsen and Sommerfeld, 1973, suggested that the following pro-
cedures could be suitable for storage of extracted water
samples. 500 ml samples of water were extracted with DDTC/MIBK
technique and subsequently the MIBK layer (approximately 40 ml)
was evaporated to dryness under partial vacuum at 50°C and to
this 35 ml of 1:1 acetone: 0.1 N HC1 was added. Such acetone
HC1 metal-containing solutions were analyzed immediately with
flame atomic absorption spectrophotometry, and again after two
weeks, in order to be compared with freshly extracted samples.
The difference between the freshly extracted samples and the
two-week old samples in acetone-HCl solution was negligible at
a concentration of 20 ng Cd/g, which had been added. The ori-
ginal cadmium concentration in lake water could not be detected,
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2-15
2.7 CONCLUSIONS
The recent awareness of the importance of accurate determina-
tion of cadmium in biological fluids and food has resulted
in a large number of publications.
Some methods presented in this chapter seem to be able to
determine levels of 0.01-0.05 in food relatively accurately.
Accurate values for cadmium concentrations in blood and urine
from exposed persons should be possible to obtain by several
of the methods presented. It is not quite clear, however, how
accurate these methods are for determination of "normal" levels
in blood and urine. Collaborative studies using different me-
thods are needed.
-------
TABLE 2:1
COMPARISON OF ANALYSIS OF CADMIUM CONCENTRATION IN GRAINS (2ND ROUND). DUPLICATE ANALYSIS WHEN
RANGES ARE GIVEN, UNIT = ng Cd/g WET WEIGHT. (From Kjellstrom et al., 1974a).
Laboratory Sample No.
1 (1971)
wheat
Neutron r 41 - 48
activation a 44.5
Keio*
University a 120
Institute of* r 133 - 144
Public Health a 139
Karolinska** r 20.7-40
Institute a 30.7
ERS, USA t a 220
Toyama Inst. r 44-51
of Hygiene a 47.5
Okayama
Universi'ty 44
National tt
Bureau of
Standards x 41
r = range a = average x =
(harvest year)
3 (1945) 4 (1971)
wheat oats
23 - 26 12-17
24.5 14.5
60 50
67 - 100
84 84
.6 17.1 - 18,3 6.1- - 7.2
17.7 6.7
53 210
32 - 36 20 - 21
34.0 20.5
33 17
20 12
only one figure significant
Estimated
5 (1941) variation
wheat coefficient (V)
22 - 22 14.1 %
22.0 -
100
107 - HI 16.5 %
109
14.5 - 21.6 27.6 %
18.1
65
23-28 9.8 %
25.5
79
35
* = low temperature dry ashing AAS without background correction.
+ = high temperature dry ashing
f+ = wet asking, extraction AAS.
t emission spectroscopy.
tt spark source mass spectromet
AAS.
ry isotope dilutions.
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2-17
AAS.
40-
30-
20 -H
10-
urine
10
20
30
NA
I ^Stockholm, Macro method,water standard
1° -"- .Micro method
IH • Keio University
IS * Institute of Public Health
T n Toyama
FIGURE 2il Comparison of cadmium analysis of urine. Neutron
activation analysis used as a "reference method"
on the abscissa. The ordinate gives results of AAS
from the five laboratories. Linear regression lines
depicted. (From Kjellstrom et al., 1974a).
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3-1
CHAPTER 3
OCCURRENCE, POSSIBLE ROUTES OF EXPOSURE AND DAILY INTAKE
In CITE, 2nd ed., data were given on the levels of cadmium in different
compartments of the environment and in food. It was concluded that
exposure via food was the most important route for the general popu-
lation, but that near cadmium-emitting industries significant amounts
of cadmium could be inhaled. Smoking cigarettes could also cause a
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3-2
due regard to the difficulties involved, they stated that all
the methodological testing suggested a good accuracy.
At the coast 1 ng/m: (west wind) and about 30 ng/m (east wind) were
recorded. In the industrial area in Liege 150 (westerly) and 441
(easterly), ng/m .were recorded and in the Lie"ge residential area 50
(westerly) and 507 (easterly) ng/m . In Brussels 10 (westerly) and
60 (easterly) ng/m were found.
These data suggest that the air levels of cadmium in Belgium could
have a high average. The short sampling period makes it impossible to
estimate monthly or yearly means.
Further evidence of transport of cadmium from zinc smelters has been
provided by Little and Martin, 1972, Ruiz and Acero, 1972, and
Buchauer, 1973. In the latter study background levels of cadmium
were reached first at 15-20 km from the smelter.
Air concentrations of cadmium at different distances from a factory
producing copper-cadmium alloys were determined during two 6-month
periods by Lind and Piscator (unpublished data). The first sampling
period was before a cleaning equipment had been installed and the
second after installment. In Fig. 3:1 it is shown that a considerable
reduction in air levels was obtained and background levels of cadmium
were reached only a couple of km from the emission source.
The interest in increasing the use of coal as an energy source has
resulted in a number of reports on cadmium in coal. Toca, Cheever
and Berry, 1973, collected particles according to size from the eff-
luent from a coal-fired boiler. It was calculated that 68% of the
cadmium was in particles with HMD less than 5 y. GlusKoter and
Lindahl, 1973, determined cadmium in 23 Illinois coals. The range
was from 0.3 to 28 u'g/g. Sorensen, Kober and Petering, 1974, deter-
mined cadmium in coal from Pennsylvania and Utah, all samples being
found to contain less than 1 yg/g.
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3-3
Fly ash from coal-fired power plants in USA was analyzed by Natusch,
Wallace and Evans, 1974. Airborne fly ash was separated according
to particle si.ze and it was found that cadmium concentrations in
the.particles increased with decreasing particle size.
An extensive study on metal release from a coal-fired power plant
has been reported by Bolton et al., 1973, 1974. Cadmium was followed
. from its occurrence in coal to deposition in soil and water. This
power.plant was found to cause relatively small increases in cad-
mium levels, e.g. in soil cadmium concentrations varied between 0.3
and 1.5 y.g/g within 5 miles from the plant. The coal used contained
0..47 y.g Cd/g.
Cadmium has been analyzed in oil imported to Sweden (Andersson and
Grennfelt, 1973). In all samples tested the concentrations were less
than 10 ng/g.
3.1..2 Cadmium in soil and uptake by plants
In CITE, 2nd ed. , it was concluded that cadmium levels in unconta-
minated or slightly contaminated areas were on an average well below
1 yg/g, whereas values from areas near cadmium-emitting industries
were far above 1 Ug/g. Important foodstuffs like wheat and rice will
take up cadmium from soil. The pH is also a key factor. The presence
of high amounts of cadmium in sewage sludge and other fertilizers
was also pointed out.
Extensive studies on cadmium in soil and its uptake in plants have
been performed in Japan by Takijima and co-workers (Takijima and
Katsumi, 1973a, b> Takijima, Katsumi and Takezawa, 1973; Takijima
Katsumi and Koizumi, 1973a, b).
Among the findings can be mentioned that analysis of rice field
soil downstream from a zinc mine revealed cadmium concentrations
ranging from 0.2 to 10.4 yg/g. In rice the concentrations found
were from 0.02 to 1.82 yg/g. There was, however, no significant
correlation between soil cadmium and cadmium in rice (Takijima
and Katsumi, 1973a).
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3-4
A highly significant negative correlation was found between soil
pH and the cadmium content of rice (Takijima, Katsumi and Takezawa,
1973). In pot experiments it was found that poultry manure de-
creased the uptake of cadmium by an increase in pH, whereas rice
straw compost did not have that effect (Takijima, Katsumi and
Koizumi, 1973a). In further experiments it was shown that treatment
of soil with a combination of calcium silicate and fused magnesium
phosphate was most effective for.reducing cadmium concentrations
in rice, resulting in concentrations about one fifth of the control
(Takijima and Katsumi, 1973b). By. treating a flooded paddy field
with hydrochloric acid (0.1 M) one-fourth of the soluble cadmium
could be removed. After drainage and washing the field was treated
with calcium silicate and magnesium phosphate. This resulted in a
reduction in cadmium concentration in rice from 0.33 yg/g to 0.06
yg/g (Takijima, Katsumi and Koizumi, 1973b).
The mechanisms behind the .uptake of cadmium by barley have been
studied by Cutler and Rains, 1974. They concluded that the most
important mechanism was diffusion and continuous fixation of
cadmium to binding sites in the barley roots.
The uptake of cadmium from fertilized soil has been extensively
discussed by Williams and David, 1973. They found cadmium
concentrations in superphosphate ranging from 27 to 48 yg/g
(atomic absorption after extraction with dithizone) and the ap-
plication of superphosphate during the years had increased the
cadmium content of soil about 5-fold. Since analysis of wheat
grain revealed low cadmium concentrations (0.012-0.036 yg/g)
they concluded that the fertilizing had little effect on cadmium
concentrations in grains. That commercial fertilizers may
contain large amounts of cadmium has also been shown by Sten-
strom and Vahter, 1974.
Huffman and Hodgson, 1973, collected samples of wheat and various
types of grass from about 100 sites in East and Central USA.
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3-5
4-gram samples were dry-ashed overnight at 450 , then wet-ashed
in nitric acid, and finally dissolved in 10 ml 0.1 N HCL. Cadmium
and zinc were determined directly in the solution with regular
flame atomic absorption, probably without deuterium background
correction. The recovery was checked with added standards
equivalent to 0.5 yg Cd/g and ranged between 85-125 %. The
total average cadmium concentration in 33 wheat samples was 0.2JO
yg Cd/g dry weight. In 120 samples of grass the average cadmium
concentration was 0.17 yg Cd/g dry weight. The zinc/cadmium d
ratio in wheat was 88 and in grass 137. ''
These data indicate up to 4 times as high cadmium concentra-
tions in American wheat as in Swedish wheat (Kjellstrom et al.,
1974b). Only a part of this difference could be due to the
drying of the samples as usually the ratio between dry weight
and wet weight for wheat grains is about 0.9. The lack of back-
ground correction in the analysis may be one reason for the
variation in recovery reported by Huffman and Hodgson, 1973,
and the average cadmium concentration in wheat may hence be
somewhat too high. The authors formulated the hypothesis that
there should be a co-variation between incidence of hypertensive
disease and cadmium concentration in plants but such a co-varia-
tion was not shown in the reported data.
Koshino, 1973, studied the yield and metal content in rice and
wheat in relation to addition of metals and various types of
fertilizer to seed. The method of cadmium analysis in grains f
was based on low temperature ashing, dissolving the ash in 1 N
HCL and directly analyzing this solution with flame atomic
absorption without background correction. This method may not
be suitable for low level samples (section 2.1) but at the yg/g-
level reliable data are probably received.
It was reported by Koshino that superphosphate contained 13.8
and 15.4 yg Cd/g wet weight in two samples. "Cd-free" (<1 yg Cd/g)
P O was added together with Cd to 10 kg (wet weight) seed in
2 5
-------
3-6
pots. The soil contained in itself 0.4 yg Cd/g (soluble in 0.1 N
HC1) , and had a pH of 5.9. As seen in Table 3:1 the Cd concentra-
tion in wheat grains increased when Cd was added. The yield of
grains decreased considerably when more than 30 mg Cd had been
added. It was 82 % as compared to the controls at 100 mg Cd ad-
dition (1.5 g P 0 ) and 11 % and 3 % respectively when 250 and
500 mg was added. Liming of the soil decreased Cd uptake and
this may be an effect of a higher pH in soil (Table 3:2).
Similar results were received for rice but the effects on yield
were more marked for wheat. Simultaneous addition of manganese,
iron and low levels of zinc alleviated the effects, giving
higher yields; copper on the other hand aggravated the damaging
effect.
The possibility of utilizing cedar trees as indicators of metal
pollution was tested by Ishizawa et al., 1974. The study was
performed in the vicinity of the now defunct Sazagawa mine in
the western part of Shimane Prefecture, Japan. There is a
history of agricultural damage from pollution by the mine, where
copper and arsenic were produced for 600 years, ending in May,
1971. Eleven cedar samples from a control area and 29 cedar
samples from the polluted area, along a river coming from the
mine and the smeltery, were taken for analysis. At the same
places, soil samples were also collected, from which the frac-
tion with a particle size less than 2 ym was analyzed. Cedar
leaves, with stalks removed, were washed in neutral EDTA (1%)
solution. The cedar leaves were dried for 12 hours at 100°C,
and then 1 g of the dry matter was dry ashed at 450 C for
12 hours. After dry ashing, the ash was extracted with 10 ml 10%
nitric acid, and subsequently analyzed with a Hitachi 207 atomic
absorption spectrophotometer. In the control area the average
cadmium concentration (dry weight) in soil was 1.5 yg/g (S.D. =
1.0). In the cedar leaves from the control area the concentra-
tion was 1.2 (±1.5) yg/g. The corresponding values for the pol-
luted area were 12.9 yg/g±16.2 in soil and 26.0±23.1 yg Cd/g in
-------
3-7
"shida" leaves. There was thus a 20-fold increase in cadmium
content of "shida" leaves as compared to a 10-fold increase in
cadmiuir. content in soil. According to Ishizawa et al., 1974,
the iron concentration in soil and "shida" bush was not dif-
ferent between the control area and the polluted area and the
manganese concentration in the polluted area was about half of
that in the control area. There was no significant difference
in the calcium concentration in soil and leaves between the
two areas. Compared to the control area, the polluted area
showed increases of 15-fold for zinc in soil versus 10-fold for;
zinc in "shida" leaves, 60-fold for copper in soil versus 2-fold
for copper in "shida" leaves, and 6-fold for lead in soil versus
0-fold for lead in "shida" leaves. From these data Ishizawa et al.
drew the conclusion that cadmium and zinc accumulate to the
greatest degree in "shida" leaves, making "shida" leaves a suitable
indicator of cadmium pollution. Ishizawa et al., 1974, also
presented data on the heavy metal concentrations in 21 samples
of mosses taken close to the.mine in the polluted area. Cadmium
concentration varied between 0.7 and 15 yg/g dry weight.
Kobayashi et al., 1973, reported cadmium, lead, and zinc con-
centrations of soil samples taken at various distances and in
various directions from the zinc smeltery in Annaka. Some of
their data have been referred to in CITE, 2nd ed., as un-
published data by Kobayashi.
One aspect concerning the air pollution around Annaka not
mentioned in CITE, 2nd ed., is the correlation between the con-
centrations of these metals. A very good agreement especially
for zinc was shown, which may indicate that zinc concentrations
~Ln soil may be used as an indicator of cadmium concentrations
in large-scale environmental studies around point sources
where both zinc and cadmium are emitted. Zinc concentrations
in this study were on the average 57 times higher than cadmium
concentrations and may therefore be easier to analyze.
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3-8
3.1.3 Cadmium in food
New data are now available on cadmium in food. These data in-
clude new values from some of the countries from which data
were furnished in CITE, 2nd ed., as well as some countries
from which values were previously not known.
In Austria Woidich and Pfannhauser, 1974, determined cadmium
in food items by a dithizone method and an atomic absorption
method after extraction with APDC-MIBK. In Table 3:3 the data
are shown. The concentrations of cadmium are extremely high in
the cereals, oats having higher cadmium concentrations than
even mussels. On the other hand, the data on cadmium in pork
meat and pork kidney agree relatively well with other data,
such as those of Hecht, Mirna and Schramel, 1973, who found
a mean concentration of 0.005 yg/g wet weight in 60 samples
of pork meat.
In U.K. an extensive survey of cadmium in food was made
(Ministry of Agriculture, Fisheries and Food, 1973). Food was
obtained from different towns and cities throughout the U.K.,
as part of a Total Diet Study. The foodstuffs were arranged
into eight groups, each with similar types of food, and made
into composite samples. When appropriate the food was also
prepared for consumption and the water used analyzed for cadmium.
Food items were also analyzed individually.
Cadmium was determined by atomic absorption spectrophotometry
in different laboratories. Samples were either wet ashed or dry
ashed. Some laboratories extracted with APDC and 4-methylpentane-
-2-ketone. The detection limit was reported to be 10 ng/g,
except for water and milk, for which it was 5 and 1 ng/g
respectively.
Altogether 4000 results were obtained. It was estimated that the
cadmium concentration in the average diet in U.K. is probably
between 10 and 20 ng/g. In individual food items the concentra-
-------
3-9
tions were found to be generally between 10 and 40 ng/g, the
exceptions being kidney, fresh carrots and potatoes, the lat-
ter (19 samples) having an average of 80.yg/g (range 10-170
yg/g). This value is surprisingly high, since the average for
composite root vegetables (where potatoes must have been in-
cluded) in the total diet showed an average of less than 20
ng/g. The same data on cadmium in potatoes are found in a c
paper by Thomas, Roughan and Watters, 1972, where it is stated
that the method used was extraction with APDC and a ketone.
Lamb meat was found to have the same average concentration as
lamb liver, 20 ng/g, which does not fit with the fact that
muscle concentrations are considerably less than liver concentra
tions as shown in CITE, 2nd ed.
The mean for all milk samples was <2 ng/g, confirming that the
cadmium content of milk is very low.
Whereas in the total diet study the average of composite fish
samples was <20 ng/g (<10-50) a separate study on fish meat
showed higher values. The range was from <30 to 750 ng/g.
In a special study on crabmeat, the average concentrations of
cadmium in dark meat from different areas around the U.K. varied
between 0.78-21 yg/g wet weight, whereas the corresponding aver-
ages for white meat were from <0.08 to 0.33. Shellfish other
than crabs also contained relatively high concentrations of cad-
mium.
This survey gives valuable information and confirms that the
levels of cadmium are generally low in most foods. Since dif-
ferent laboratories analyzed the samples and interlaboratory
comparisons are not reported, the results must be regarded as
only approximate. There are some obvious inconsistencies between
e.g. data on fish from two studies.
Thomas, Roughan and Watters, 1973, reported on cadmium in canned
fruit and vegetables consumed in U.K. Cadmium was determined by
-------
3-10
atomic absorption after extraction with APDC and 4-methylheptane-
ketone. Most fruits contained around or less than 10 ng/g, of
canned vegetables, only spinach having a relatively high concentra-
tion, 80 ng/g (range 30-180 ng/g).
In Canada, Kirkpatrick and Coffin, 1973, determined cadmium by
atomic absorption with background correction in 190 cured meat
samples. In Table 3:4 it is seen that the average varied between
<10 and 30 ng/g in all groups. These are relatively low con-
centrations, but in view of the difficulties in determining
cadmium in meat, they might well be lower.
Horwitz and van der Linden, 1974, determined cadmium in 5 brands
of tea and 7 coffees, the average for both being 30 ng/g. It was
calculated that a cup of coffee or tea contained from 50 to 220
ng cadmium.
Beckman et al., 1974, determined cadmium by atomic absorption
>
with background correction in liver and kidneys from cattle,
pigs, sheep and horses in Sweden. In Table 3:5 it is seen that
in kidneys the cadmium concentrations are relatively high even
in young animals, and the liver concentrations are generally
above what is found in other foods. In horse kidney and liver
cadmium concentrations were quite high.
A special study on baby foods was done in U.K. by Snodin, 1973.
Cadmium was determined by atomic absorption after extraction into
DDDC-MIBK (DDDC = diethyl ammonium diethyldithiocarbamate). In
Table 3:6 the results are presented. It should be noted that can-
ned and bottled food are consumed as they are, whereas some of
the dried foods, e.g. milk, have to be reconstituted before con-
sumption. These data show higher levels in baby food than those
presented in the above mentioned, extensive U.K. study. Further
confirmation of the low levels of cadmium in milk has been given
by Cornell and Pallansch, 1973. By using a pulse polarographic
technique they found average concentrations of 0.12, 0.74 and 0.23
yg/g by repeated sampling of milk from 3 cows.
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3-11
Sugiyama, Ishizawa arid Yoshida, 1974, studied the heavy metal
content of various organs of Japanese squid: liver muscle, testis,
"sexual gland", ovarium, "squid uterus", and contents of the'
stomach. Forty immature and mature squid were analyzed. The
average cadmium concentration (dry weight) in liver was 160±114
(S.D.) yg/g, and the zinc concentration 121±64 yg/g. In meat the
concentration of cadmium was 1.9±1.0 yg/g, and the zinc concentra-
tion 64±8 yg/g. On the other hand in testis, ovarium and "sexual
glands" the zinc concentrations were about 60 times higher than
the cadmium concentration. Cadmium in testis was e.g. 2.3±1.9 (j
yg/g, whereas the zinc concentration was 135±31 yg/g. The wet
weight concentration of metals is not presented in the paper.
Enomoto and Uchida, 1973, reported data on cadmium contents of
various seafoods from the Ariake Sea in southern Japan. Parts
of the area are polluted by e.g. the zinc-refineries in Omuta
but other parts may be basically non-polluted by cadmium. Atomic.
absorption after wet ashing and extraction was used for cadmium
analysis. The muscle of one type of fish (sarubou) caught at 4
different places contained 1.01-6.29 yg Cd/g dry weight (0.2-1.3
yg/g wet weight) and the corresponding internal organs contained
11.5-24.7 yg Cd/g dry weight (0.23-4.9 yg/g wet weight).
In muscles of various fish bought at the market in Saga, a city
in the vicinity of the Ariake Sea, the concentrations were 0.04-
0.26 yg Cd/g dry weight (0.008-0.05 yg/g wet weight). Canned sea-
foods were also analyzed giving e.g. an average of 0.15 yg Cd/g
dry weight in 8 samples of mackerel from a non-polluted area in
San-in area, .an average of 5.0 yg Cd/g dry weight in 15 samples t
of oysters from Hiroshima Prefecture and an average of 3.9 yg
Cd/g dry weight in 10 canned samples of "Akagai" from Ariake Sea.
Akita et al., 1974, studied the transfer of cadmium from rice
and various vegetables to water solutions. Dried samples of
polished rice (original cadmium concentration 2 yg/g dry weight)
were kept in water for 24 hours at 25°C, 30°C and 50°C. The
cadmium lost to water was 3-5 %. When leafy green vegetables
were boiled for 10 minutes 34-61 % of their original cadmium
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3-12
contents (0.04-1.58 yg/g) were lost to water while root crops
(sweet potato/ etc.) lost between 6 and 45% (0.33-1.55 yg/g).
Cadmium was analyzed with flame atomic absorption after wet
ashing and APDC/MIBK-extraction.
3.1.4. Cadmium in cigarettes
In CITE, 2nd ed., it was concluded that a cigarette contains from
1 to 2 yg of cadmium and that about 10 % of that amount may be
inhaled.
Unterhalt and Pindur, 1972, determined the cadmium content of 4
cigarettes by atomic absorption and found a mean amount of 1.44
yg per cigarette. The mainstream smoke from 10 cigarettes was
collected and an average of 0.33 yg was said to be contained in
that fraction. The technique is not described and no certain con-
clusions can be drawn, since standardized techniques should be
used for such studies.
Since smoking will cause significant increases in body burden of
cadmium it is of interest to know whether there have been changes
in the cadmium content of cigarettes with time. Such a study has
been performed by Li.nnman, Lind and Kjellstrom (to be published) .
Eighteen brands of cigarettes produced in the years 1918-1968
were analyzed. In Fig. 3:2 it is seen that with one exception
the concentrations are similar to those found today, with no
tendency toward an increase.
Lettuce leaf cigarettes, which are used as a substitute for
tobacco, were examined by Elia, Menden and Petering, 1973. The
average cadmium content was 1.39 yg per cigarette. These cigaret-
tes were smoked in a smoking apparatus using a standardized
procedure. In the mainstream only 0.01-0.02 yg was found, which
is less than what has been found in ordinary cigarettes. On the
other hand more cadmium was emitted into the air via the side-
stream.
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3-13
3.1.5. Changes in cadmium concentrations in food over time
A question of importance is whether or not the present daily cad-
mium intake in a given area is different from the cadmium intake
in the same area years ago. Due to the very long biological half-
time of cadmium in the critical organ, the kidney (CITE, 2nd ed.),
such data are necessary for a meaningful evaluation of the dose.
Due to the problems of analyzing cadmium in a reproducible way
at the low concentrations in common foodstuffs (see Chapter 2),
i
it is doubtful as to whether studies performed at different
times by different laboratories can be compared. One good
alternative might be to analyze cadmium in old foodstuffs, which
for one reason or another have been preserved to the present day.
Kjellstrom et al., in press, analyzed the cadmium content
in Swedish wheat samples harvested in the same geographical area,
Uppsala and environs: 31 samples of spring wheat from
1917-1972 and 45 samples of fall wheat from 1916-1972; Data on
meteorological factors and fertilizers were available from past
records. Some studies on barley were also performed.
The samples were treated in a completely blind fashion (duplicate
analysis) according to the method by .Kjellstrom et al., 1974b.
There was a wide scatter between the individual values (Figures 3:3
and 3:4), but for the whole 50-year period, there was a statistical-
ly significant increase in the average cadmium concentration in
fall wheat. In spring wheat such an increase occurred between
1916 and some time in the 1950's. There was a very strong within-
year correlation between the cadmium concentrations in different
genotypes of wheat and between wheat and barley harvested in the
same area. This suggests that some meteorological, agricultural
or pollution factor, or a combination of such factors, related
to the individual year could explain the variation in the cadmium
concentration. Statistical analysis did not reveal any correlation
between cadmium concentration and any of the following factors:
yield, average summer temperature, average summer rain, type or
amount of fertilizer applied. The zinc concentration in grains
-------
3-14
did not show the same pattern, and the ratio of cadmium to zinc
in wheat increased in the same fashion as cadmium concentration
itself.
»*
Kjellstrom et al., in"press, concluded that the increase
in average Cd-concentration in fall wheat may be caused by ac-
cumulated effects of air pollution and fertilizers.
3.2 PRESENT DAILY INTAKE OF CADMIUM
In CITE, 2nd ed., it was concluded that the daily intake of cadmium
in non-polluted areas probably was around 50 yg.
In the large study in U.K. (see 3.1.3) it was estimated that the
average intake there was between 15 and 30 yg per day. In another
study from U.K. an average intake of 64 yg was estimated (Hamilton
and Minsk!, 1973).
Guthrie, 1973, reported that the average intake of cadmium by 11
women in New Zealand was 48 (21-104) yg per day. The method was
atomic absorption without background correction. The author later
corrected these values for background interference and reported
in an addendum that the intake was 21 (7-76) yg.
Wester, 1974, in a metabolic study, determined cadmium intake
by analyzing duplicates of the daily diet in a Swedish hospital.
Mean values for 4 subjects during two 5-day periods were 10-11
11-12, 5.1-6.0 and 9.6-13 yg. The method was neutron activation.
The corresponding values in feces were 9.8-7.2, 13-13, 6.5-4.8
and 8.9-3.4, thus showing, except in one observation, good
agreement with the intake values.
The daily intake of cadmium in Japan has been discussed in a
review by Yokohashi, Suzuki and Matsubara, 1973. There are un-
published data by Ro, Suzuki and Tanaka, regarding cadmium in
food, beverages, feces and urine of one 38-year old male subject.
-------
3-15
Samples had been taken every day for 30 days, showing an average
daily cadmium content in food and drinks of 45.7 yg, in feces of
32.6 yg, and in urine 4.2 yg. The analytical method was based on
atomic absorption, but no further details were given. The food
and feces .data indicate an absorption of about 30% of alimentary
cadmium, which is a figure much higher than earlier reported
(CITE, 2nd ed.). This may be explained by analytical errors.
Apart from this, these data resemble the data on the Japanese
cadmium intake previously compiled (CITE, 2nd ed.).
Tati, Katagiri and Kawai, to be published, determined the fecal
output of cadmium for 5 days in 7 Japanese students. The average
output varied between 41.1 and 79.4 yg/day and assuming 5 %
absorption the daily intake was estimated to be from 43.3 to
83.6 yg per day.
Data on fecal concentrations of cadmium are given by Johnsson et al.,
1974. They found in 6 different population groups (n = 27-41) in
Houston, Texas, mean values varying from 0.19-0.30 yg/g. Assuming
the average fecal daily weight to be as high as 200 g this would
correspond to a daily output of 38-60 yg, which corresponds to
a daily intake of 40-63 yg. This is a very rough estimate based
on a high weight of the daily feces, and the true values are
probably lower.
3.3 CONCLUSIONS
New data confirm that the "normal" levels of cadmium in air are
less than 1 ng/m and that in industrialized areas considerably
higher levels may be found. Further studies on uptake of cadmium
in plants confirm that increasing the pH of soil reduces the up-
take.
New data on cadmium in food confirm that the levels generally are
low in most foods, but that internal organs may contain high con-
centrations.
A change in the cadmium content of cigarettes with time has not
been demonstrated. Studies on wheat indicate a slow but
-------
3-16
significant increase in cadmium concentrations with time in
wheat grains in a Swedish area.
Earlier estimates of the daily intake of cadmium in non-polluted
areas in Japan have been confirmed, i.e. around 50 yg, whereas
new data from U.K., Sweden and New Zealand indicate that the in-
take there may be 10-30 yg.
-------
TABLE 3:1
EFFECT OF CADMIUM AND PHOSPHATE APPLICATION ON CADMIUM CONTENTS IN WHEAT (From Koshino, 1973).
Application rate
P205
(g)
0.5
1.5
4.5
1.5
1.5
Cd
Others
(mg)
0
100
0
30
100
250
500
0
100
0 limed
100 limed
0 granular
30 granular
3/20
Tops
0.2
25
1.2
34
40
34
34
1.7
43
0.6
16
0.4
13
Cd content
4/30
Tops
0.1
16
0.3
8.1
16
8.5
23
0.4
14
0.1
5.6
0.3
5.4
Root
1.1
79
1.0
29
78
81
400
1.8
55
2.8
31
0.6
14
(yg/g air-dry basis)
at the
Straw
0.4
9.8
0.6
5.2
10.8
8.0
18.6
0.4
10.2
0.4
3.8
0.4
4.5
harvest
Grain
0.16
2.7
0.12
1.6
2.3
2.2
2.4
0.16
2.9
0.13
1.3
0.10
1.0
(6/17)
Abortive
grain
0.0
0.15
1.9
2.4
0.11
3.3
0.14
1.5
0.3
1.8
Root
4
142
5
209
343
97
120
20
401
20
279
3
63
Cd uptake (yg/pot)
at the
Straw
6
45
19
176
266
30
19
20
409
15
147
15
136
harvest
Grain
1.0
1.9
2.2
32
35
4.8
0.1
6.2
108
3.0
29
3.1
21
(6/17)
Whole
plant
11
189
26
418
645
132
139
46
920
38
460
21
220
Tops
7
47
21
210
302
35
19
26
519
18
181
18
157
-------
TABLE 3:2
ANALYSIS OF THE SOIL AFTER CROPPING WITH WHEAT (OVEN-DRY BASIS)
(From Koshino, 1973).
P205
(g)
0.5
1.5
4.5
1.5
Cd
(mg)
o
,100
0
30
100
250
500
0
100
0*
100*
PH
(KC1)
5 .5
5.4
5.5
5.5
5.5
5.7
5.7
5.4
5.5
6.3
6.7
0.1 N
Cd
0.2
32.5
0.4
17.4
34.5
120
170
0.4
32.5
0.4
26.3
HC1 soluble (yg/g)**
Zn
35
37
26
35
32
46
24
32
47
34
Mn
26
24
24
32
28
29
20
27
40
40
29
Cu
15
15
16
16
17
16
15
15
15
15
' 10
-¥•
Limed with 50 g CaCOs.
* Soil/solvent ratio is 1/5 for Cd and 1/10.for other metals,
-------
3-19
TABLE 3:3
CADMIUM CONTENT IN FOODSTUFFS (From Woidich and Pfannhauser,
1974).
Type
No.
Cadmium
yg/g wet weight
Range Mean
Corn
Wheat
Oats
Barley
Rye
Mussle
Tuna-fish
Sardine
Fish (except tuna-
fish and sardine)
Pork kidney
Pork
3
13
4
4 .
4
39
13
27
65
15
15 .
0
0.
0
0.
0
<0
<0
<0
0
0.
.59-1
006-1
1.1-1
.05-0
125-0
.05-1
.05-0
.05-1
.05-1
.01-0
008-0
.05
.05
.93
.17
.27
.74
.97
.00
.46
.41
.025
0
0
0
0
0
0
0
.24
.31
-14
.23
.13
.15
.014
-------
TABLE 3:4
CADMIUM CONCENTRATIONS IN CURED MEATS (FRESH WEIGHT BASIS)
(From Kirkpatrick and Coffin, 1973).
Meat type
A-l
A-3 ' "
A-4
A-5 -
A-6
A-7
B-l
B-2
B-3
B-4 :
Total
Ready-
con tai
No.
samp
15
17
20
20
25
15
18
23
14
23
190
to-eat
ners )
of Cd (;yg/g)
les Range
<0. 01-0. 22
<0. 01-0. 04
<0. 01-0. 07
<0. 01-0. 04
<0. 01-0. 05
<0. 01-0. 09
<0. 01-0. 06
0.01-0.06
• <0. 01-0. 06
<0. 01-0. 08
<0. 01-0. 22
cured meat products canned
cured meats
Mean
0.02
0.01
0.03
0.02
0.02
0.03
<0.01
0.03
0.02
0.02
0.02
(in metallic
A-l =* Shelf-stable
A-3 =
A-4 =
A-5 =
A-6 =
A-7 =
B-l
B-2
B-3
B-4
Packaged (non-metallic) cured meats
Wieners - including smoked and unsmoked
Bologna
Meat loaves (luncheon meat slices, sliced ham, mock chicken,
macaroni and cheese, luncheon meat slices, etc.)
Salami, including various sausage products such as European
type sausages.
Unpacked cured meat products
Pastrami, smoked meat, dried uncooked (Westphalian) ham etc.
Cured meat products requiring further cooking by the
consumer
Bacon
Hams
Picnics (shoulders)
Corned beef products
-------
3-21
TABLE 3:5
CADMIUM CONTENTS IN KIDNEY AND LIVER OF SOME
FOOD-PRODUCING MAMMALS [From Beckman et al., 1974)
Cadmium, .Ug/g
Species No. Age, years Kidney Liver
. m r m r m r
Cattle 9 0.21 (0.12-0.33) 0.25 (<0.02-0.75)' 0.06 (<0.02-0.17)
Cattle 28 2.9 (0.42-12) 0.62 (0.11-3.2) 0.11 (0.03-0.33)
Pig 12 0.47 (0.37-0.58) 1.02 (0.16-3.1) 0.12 (0.04-0.24)
Sheep 16 1.06 (0.33-4.00) 0.43 (<0.02-'3.5) 0.34 (<0.02-2.8)
Horse 13 12 (1.0-26) 31 (4.3-90) 2.6 (0.15-6.7)
Foal 1 0.08 0.04 0.04
m = mean
r = range
-------
TABLE 3:6
CADMIUM CONTENTS OF SOME TYPES OF BABY FOOD
(From Snodin, 1973).
Food-
Dried milk
Dried Cereal
Canned Foods
Bottled Foods
No. of
samples
8
15
.7
. , 7
Cadmium
uq/q
0.020
0.035
0.036
0.026
(me
-------
3-23
Cd
pg
1.0-1
0.1-
0.01-
o.ooi-
A Before emission reduction
• After emission reduction
0.1
1.0 10.0
Distance in km
from emission
source
FIGURE 3:1
Average cadmium concentrations in air at
different distances from a factory producing
copper-cadmium alloys. Continuous sampling
was performed during May-December 1971, and
May-December 1972. Each sample represented
24 to 72 hours. In December 1971 emission-reducing
equipment was installed (From Lind and Piscator/
unpublished data).
-------
3-24
Cd /ug
5-
4
3
2-
1-
1920
1930
1940
1950
1960
1970 year
FIGURE 3:2 Cadmium concentration in cigarettes of different ages
(vSf/g d*Y weight) . (From Linnman, Lind and Kjellstr6m,
1974).
-------
3-25
100-
50^
ng Cd/g wet weight
in grains
Year
1910 -20 -30 -40 -50 -60 -70
FIGURE 3:3 Cadmium concentration in spring-wheat from Uppsala,
' Sweden. (From Kjellstrom et al., in press).
-------
100-
50-
ng Cd/g wet weight
in grains
3-26
• Fa 1 1 wheat, Uppsala
o Fa 1 1 wheat, other areas in Sweden
---- Regression line, Uppsala
•
•
Year
1870 -80 -90 1900 -10 -20 -30 -40 -50 -60 -70
FIGURE 3:4 Cadmium concentration in fall-wheat from Uppsala
and other areas in Sweden. (From Kjellstrom et al.,
in press).
-------
4-1
Chapter 4. METABOLISM
4.1 UPTAKE AND ABSORPTION
In CITE, 2nd ed., it was concluded that cadmium will mainly
be absorbed from the lungs and the gastrointestinal tract, even
if under certain circumstances soluble cadmium compounds may be
absorbed from the skin. A recent report (Kimura and Otaki, 1972)
on percutaneous absorption of cadmium chloride in mice and
rabbits after repeated applications in water solution or in
ointment confirmed earlier results, e.g. cadmium may also
enter via the skin, about 0.5% of the applied amount being
deposited in liver and kidneys. There are no data on absorption
after exposure via skin in human beings.
4.1.1 Respiratory deposition, clearance,and absorption
In CITE, 2nd ed., it was concluded that inhaled cadmium is
absorbed and retained to a considerable degree. Human data
were scarce, but it was estimated that up to 50% of inhaled
cadmium fumes may be absorbed. Animal data indicated an
absorption of 10 - 40%.
There are no human studies available primarily designed for
determination of the pulmonary handling of cadmium, but
evidence presented in sections 4.3.2 and 4.3.3 indicates that
cadmium from cigarettes must be absorbed to a high degree.
One animal experiment has been reported. Moore et al., 1973,
studied the fate of radioactive cadmium after different
administration routes. In inhalation experiments rats
(numbers not given) were exposed to a Cd chloride aerosol
at a concentration of 1,800 yg Cd/m . Exposure time was four
hours. The mean diameter was about 0.5 micron. Measurement
of mcd in the lungs of animals sacrificed immediately
after cessation of exposure indicated a retention of 9.7%
of the total inhaled 115mcd (using a minute volume of 0.1 liter
for calculating the amount of inhaled cadmium). Unfortunately
no data are given on cadmium concentrations in liver and
kidneys. About 60% of the cadmium in the body was at that
time found in the gastrointestinal tract.
-------
4-2
The biological half-time after the first rapid initial clearance
during the first week was about 200 days as measured by whole body
counting. This half-time was about the same as was found in other
exposure routes as seen in Figure 4:1.
4.1.2 Gastrointestinal absorption
4.1.2.1 Ga£t£oin1:e£t_inal_absorp_tipn in_animals
In CITE, 2nd ed., it was concluded that the gastrointestinal
absorption rate is usually about 2% in animal experiments.
The absorption should be increased considerably by low calcium
or low protein intake.
109
Suzuki, Taguchi and Yokohashi, 1974, gave Cd by stomach tube as
a single exposure to two Macaca irus monkeys, who weighed 3.60
and 3-. 13 kg. The night before the experiments the monkeys were
/ -, i no
.thirsting. In the morning 105 yCi carrier free CdCl- was given
to monkey A after which he was allowed to drink and eat freely.
109
Monkey B received 57 yCi CdCl_ in the same fashion, but in
this case mixed with non-radioactive cadmium chloride, such that
1 mg of cadmium was given in 10 ml solution (concentration 100 yg
Cd/g). Monkey A was killed after 19 days, and monkey B after 25
days, and the cadmium content in the various organs was measured
with scintillation counter. During the experiment feces and
urine were collected each day and cadmium content measured.
In Figure 4:2 the distribution of the dose given to monkey A is
depicted. It is seen that 12 % of the dose is retained after 19
days, and the larger part of this retention is still in the
gastrointestinal tract. The retention in the rest of the body
is 5.3 %; for the other monkey (B) this figure was 6.35 %.
Using the whole body cadmium concentration as a reference,
Suzuki, Taguchi and Yokohashi underlined the relative concentration
of cadmium in the epithelium of the small intestine. The /
concentration is about 33 times higher than the average body
concentration, and in the duodenum it is more that 50 times
higher. The only other organ where such high cadmium concentrations
are found is the kidney, where the cadmium concentration is
about 20 times higher than the average concentral^on
-------
in total body. The initial high concentration in duodenal
mucosa has also been observed by Fox, 1974.
Suzuki and Taguchi, 1972, had earlier reported a similar experi-
ment on another Macaca irus monkey. The retention rate in whole
body except for the gastrointestinal tract was 0.65 %. The new
data by Suzuki, Taguchi and Yokohashi, 1974, indicate that the up-
take of cadmium from the gastrointestinal tract is a slow process,
taking several days, or even weeks. The daily fecal excretion has ;
phases each following an exponential decrease. During the first
week of the experiment the half-time is 1 day, during the second
week about 2 days, and after the second week about 41 days. In the
1974 experiment, absorption rate is similar between the two
monkeys even though one received carrier free cadmium and the
other received cadmium with carrier.
Moore et al., 1973, gave rats(number not stated) single oral
doses of 115mCdCl2/ 50 yCi by stomach tube. After the initial
rapid elimination about 3 % of the dose was retained after 4
days and 2.3 % after 10 days, as shown in Figure 4:1, indicating
that absorption must have been of that magnitude.
A long-term study was performed by Ogawa et al., 1973. For 30
days they gave two groups of mice radioactive cadmium in drinking
water. One group was given 50 yCi/1 of carrier free" mCdC!2
solution (containing 0.35 yg/g of cadmium) .and the second group
was given 50 yCi/1 of carrier containing mCdCl_ in water
(containing 146 yg/g of cadmium). The animals were allowed to
drink ad libitum. Whole body radioactivity was measured at one
week intervals up to day 31. It was found that whole body reten-
tion of Cd was significantly less in the carrier group. It
was also calculated that the average cadmium uptake for 30 days
was 0.56 yg/day in the first group and 100 yg/day in the second
group. This gives a ratio of about 200 meaning that the high
exposure group retained only about 50 % of what could be expected
were the retention proportionate to the exposure. The authors
concluded that absorption of cadmium was lower at the higher ex-
posure level. When liver and kidney are studied alone the
corresponding figures will be 140 and 40 % respectively. It is
not clear from the description of the experiment whether the
-------
4-4
daily consumption of water was similar in the respective groups.
Since the high dose caused toxic symptoms, the intake might have
been less in that group.
Matsusaka et al., 1972, studied whole body retention of
mCdC!2 after single and repeated peroral infusions via gastric
tube to adult mice and young mice of the age 7, 14 and 21 days.
Cadmium retentions after single exposure (Figure 4:3) are higher
in the younger mice (five animals in each group). As seen in
the same figure the retention of CdCl- injected intravenously is
almost 100%. Because the retention pattern of the 7-day old
mice differed from the others Matsusaka et al. repeated the
experiment on 20 such mice and killed them 1, 5, 10 and 20 days
after single exposure. The cadmium content of the intestines
was deducted from whole body and it could be shown that the
actual gastrointestinal absorption in these mice was 8.1 - 9.2%
1, 5, 10, and 20 days after exposure. Repeated exposure of
adult mice and 7-day old mice during 10 days showed that the
excretion of infused cadmium was much slower from day 7-15
after birth. The data indicate that gastrointestinal handling
of cadmium in 7-day old mice may be the cause of the different
retention patterns. Whether the differences in total retention
between different age groups also are caused by this factor
is not possible to say.
A long-term study on lambs has been performed by Doyle et al.,
1974. Five groups with six lambs in each were fed cadmium-
containing diets for 191 days. The diets contained 0, 5, 15,
30 and 60 vg/g cadmium. After 163 days the animals were
transferred to metabolism stalls for 21 days subsequent to
which a 7-day absorption study was performed. Cadmium intake
and absorption were determined from food and feces data.
Only absorption data on the control group and the group given
60 yg Cd/g of diet are given in the paper. The control lambs
had a mean intake of cadmium of 180 pg/day and the absorption
was calculated to be 11%. The intake in the exposed group
was 119 mg/day and the absorption was calculated to be 5%.
Since the urinary excretion of cadmium in controls was reported
to be higher (45 yg/lamb/day) than in the highest exposure group
(36 pg/lamb/day) there is reason to doubt the reliability of the
analytical methods.
-------
4-5
The influence of cholecalciferol (vitamin D ) on the absorption
of cadmium has been studied by Cousins and Feldman, 1973. In one
experiment male chicks were given a vitamin' D deficient diet
containing 1 % calcium for 28 days. On the 27 th day of life one
half of the group received 2000 I.U. of cholecalciferol orally.
109
18 hours later each chick received 5 yCi of Cd orally. After
a 24-hour fast the chicks were killed. The cadmium content of
liver and kidney of the chicks given vitamin D was higher than
in non-treated animals, but the difference was not significant.
In another experiment chicks were given the -vitamin D deficient
diet for 23 days, and then for 4 days half of the group received
600 I.U. of cholecalciferol per kg of diet. On the 5th day all
chicks received 5 )_i(
chicks were killed.
109
chicks received 5 uCi of - Cd orally. After a 24-hour fast the
This experiment likewise revealed no difference between the
groups with regard to liver and kidney levels of cadmium. It
was concluded that vitamin D does not have a direct influence
on the uptake of oral cadmium into the liver and kidney. The
results from this study are thus in contrast to earlier work
presented in CITE 2nd ed., where it was mentioned that Worker and
Migicovsky, 1961, had shown that vitamin D had an effect on
cadmium metabolism. The difference is, as discussed by Cousins
and Feldman, that in the present study the animals were receiving
a sufficient amount of calcium,'whereas in the study by Worker
and Migicovsky a low calcium diet was given. It has indeed been
documented in CITE 2nd ed., that calcium deficiency causes an
increase in the absorption of cadmium.
Long-term studies on rats have been reported by Ishizaki, 1972.
Two basic diets were employed, one with high protein - high calcium
and one with low protein - low calcium content. Cadmium concentra-
tions in the diets were varied by adding rice with high and low
cadmium content. Eleven male and eleven female groups were used
and after 28 weeks cadmium was analyzed in liver and kidneys. It
was found that rats on low calcium - low protein diets accumulated
more cadmium than rats on high calcium - high protein diet.
Regardless of diet, it was seen that females accumulated more
cadmium than males. The mean retention after 28 weeks was 0.47 % in
4 low protein - low calcium groups receiving between 0.9 and 8.55
-------
4-6
yg Cd/g of diet , and 0.28 % in 2 groups on high protein - high
calcium diet and with 2 and 2.57 yg Cd/g of diet. These findings
support the findings discussed in earlier reports. In a brief note,
it was reported (Washko and Cousins, 1974) that calcium deficiency
caused higher retention of orally given cadmium in male rats.
Pribble and Weswig, 1973, compared the uptake of cadmium in
water and food respectively. Weanling rats, 10 of each sex in
three groups, were given a normal diet, a diet with added
cadmium chloride 5 yg/g food, and cadmium in water, 5 yg/g for
18 months. The intake of water per weight was 50 % higher
than the intake of food. The accumulation in liver and kidney
was about 2.5 times higher in animals given cadmium in water
and the difference in intake could not explain this difference.
The authors postulated that cadmium in water could be more
easily accessible than cadmium bound to organic molecules in
the food.
4.1.2.2 In_human_beings_
In CITE 2nd ed., it was stated that ingested cadmium was absorbed
to about 6% in human beings, but that low calcium intakes might
well cause higher absorption.
Yamagata, Iwashima and Nagai, 1974, studied the gastrointestinal
uptake of radioactive cadmium in a 53-year old male. Rice was
grown in pots to which mCd was added and at the time of the
experiment 20 g of this rice was available, containing a total
of 1.5 yCi Cd. The rice was mixed with regular polished rice
to make a total amount of 100 g, which was eaten at one time and
whole body counting was performed during 144 hours. Figure 4:4
shows the decrease in whole body content of radioactive cadmium.
Yamagata, Iwashima and Nagai also collected 24-hour samples of
feces and urine from the subject during the first three days of
the experiment. In feces the excretion was 76.2, 15.8 and 1.2 % of
the given dose, and in urine 0.7, 0.0 and 0.9 %. These analyses
were also performed by measuring radioactivity. The total excretion
during three days was .95 %, a figure which fits well with the
retention value in Figure 4:4. After six days the retention was
4 .4 % of the given-.dose. The authors concluded that the gastrointes-
tinal absorption in human beings may well be 5-7 %.
-------
4-7
Robinson et al., 1973, performed a metabolic balance study in 4
human beings aged 19-25 years. The duration of the study was 27
days, divided into three 6-day experimental periods, a 6-day
preliminary period and a 3-day post-period-. The diet was invariably
meat loaf, ice cream, tea and coffee. During the different periods
a constant amount of food was given each day, and it was thus
possible to calculate the daily intake for each subject. The
mean daily intake of cadmium in the 4 subjects was estimated to be
60-92 yg/day. Daily collections of urine and feces were made.
For analysis of cadmium atomic absorption was used, cadmium in
urine being determined by direct method with standard additions
of cadmium and cadmium in food and feces being determined in acid
digest. Background correction was not utilized. Urinary excretion
of cadmium was found to be from 14-54 yg/day according to the
method applied, and it was estimated that between 36 and 41 % of
dietary cadmium was excreted in urine. The fecal excretion was
calculated to vary between 42 and 74 % of the intake in the
4 subjects. Since data from other human studies have clearly
indicated that less than 10 % of ingested cadmium is generally
absorbed the data from this study are obviously quite erroneous.
The methods chosen are not of sufficient accuracy for determina-
tion of cadmium in biological material.
4.1.3 Placental transfer
Ishizu et al., 1973, gave pregnant mice single subcutaneous
injections of 2.5 mg Cd/kg as cadmium chloride on the 7th day of
gestation. In placenta the cadmium concentrations were about 10
times higher than in the placenta of controls, whereas cadmium
concentrations in the fetuses were similar, being about 0.003 yg/g.
Mean concentrations of 17 yg/g and 0.19 yg/were detected in the
liver and placenta respectively in the cadmium-injected mothers.
These data indicate that the subcutaneous injection of relatively
large doses of cadmium does not cause any significant accumula-
tion of cadmium in the fetus. This is in contrast to some
earlier animal studies, discussed in CITE, 2nd ed., where it
was shown that exposure to large amounts of cadmium, via intra-
venous injections could cause uptake in the fetus.
-------
4-8
The dose given was shown to cause malformations, possibly due to
an indirect effect of cadmium rather than to a direct one.
Interference with zinc metabolism might well be responsible.
4.1.4 Conclusions
New animal data on absorption after inhalation give further
evidence that cadmium is retained for long times after respiratory
exposure. Additional proof has been obtained that low calcium
intakes cause increases in gastrointestinal absorption of cadmium.
There is an indication that differences exist between absorption
rate for cadmium compounds in water and foodstuffs, a problem
that should be further studied. New data on gastrointestinal
absorption in a human being confirm that about 6 % of ingested
cadmium is absorbed.
4.2 TRANSPORT, DISTRIBUTION AND EXCRETION OF CADMIUM IN ANIMALS
4.2.1 Uptake to and clearance from blood
In CITE 2nd ed., it was concluded that after a single injection,
cadmium will initially be in the plasma,but during the first 24 hours
after injection a rapid clearance from plasma takes place so that
eventually the concentration in the cells will exceed that in
the plasma. After repeated exposure cadmium will mainly be found
in the blood cells, bound to proteins, such as metallothionein.
Yoshikawa, 1973, studied the distribution of cadmium in rats.
Twenty rats were given 0.6 mg of cadmium/kg body weight intraperi-
toneally and 24 hours later that group and another untreated
group of 20 rats received intraperitoneally 3 mg cadmium/kg body
weight. Four rats in each group were killed 2, 6, 24, 72 and 168
hours after the last injection. Cadmium was determined in red
cells and in plasma. Figure 4:5 shows a tendency to falling levels
in red cells in non-pretreated animals during the first six hours,
but later on an increase, whereas in pretreated animals such an
initial drop in cadmium concentrations in the cells is not seen.
-------
4-9
Plasma levels 6 hours after injection were considerably higher
in the animals without pretreatment than in pretreated animals.
The results in animals without pretreatment are in accord with earlier
findings presented in CITE 2nd ed., where it was assumed that
the second increase in red cell concentrations had to do with the
formation of metallothionein, which had been found in red cells
24 hours after injection. These new data support the assumption
that the formation of metallothionein is connected with the uptake
of cadmium in the red cells.
Cadmium in blood was followed by Matsubara-Khan, 1974, for 128
109
days after a single subcutaneous injection of 1.7 yCi of Cd
as cadmium chloride in 40 male and 40 female mice. Figure 4:6
shows the cadmium levels in blood at different times after injection,
The biological half-time in blood was calculated by the author
to be 29 days.
4.2.2 Tissue distribution and retention
In CITE 2nd ed., it was concluded that cadmium was mainly stored in
liver and kidneys. The distribution between these two organs will
depend on route of administration and dose. Thus long-term low
level oral exposure will cause high concentrations in kidney
and relatively low concentrations in liver, whereas short-term
exposure to high amounts will cause high liver levels. After
exposure has ceased there will be a redistribution so that eventual-
ly the renal levels will increase and liver levels decrease.
The accumulatio*h of cadmium in these two organs is related to the
metabolism of metallothionein, the cadmium-binding protein. If
renal damage occurs due to the accumulation of cadmium, the ex-
cretion of cadmium will increase, which may decrease renal levels
considerably.
In the experiment by Yoshikawa, 1973 (section 4.2.1),
it was seen that both at 6 and 24 hours after the last
injection the liver concentrations of cadmium were signi-
ficantly higher, more than 50%, in the pretreated group
than in the other group. In other organs there was no such
-------
4-10
statistical difference between the groups. The author concluded
that pretreatment accelerated the accumulation of cadmium in the
liver.
Matsubara-Khan, 1974, studied the fate of radioactive cadmium,
109
Cd as a subcutaneous injection, the dose being 1.7 yCi/mouse.
Animals were killed at different intervals from 1-128 days.
Matsubara-Khan applied mathematical models for calculating
biological half-time from the empirical data. When the average
cadmium concentration in a given organ decreased among 10 mice
already from the first day after injection a one-compartment
model was used; when organ concentrations showed a transitory
increase at the beginning a two-compartment model was used.
Maximum liver levels were reached on day 8 after injection.
Thereafter there was a decline in liver levels to day 128.
The biological half-time in liver was calculated to be about
63 days. Maximum renal levels of cadmium were reached about
32 days after injection, subsequent to which they slowly declined.
The author calculated the biological half-time in kidney to be
990 days, but as seen in Figure 4:7 an obvious decrease took
place from day 32 to 128, which may indicate that the half-time
in mouse kidney in fact is shorter than calculated. She also
studied the salivary glands and estimated the half-time there to
be 433 days. When the same author followed the fate of orally
109
administered Cd, 5 wCi/mouse, h<
were 43 and 433 days respectively.
109
administered Cd, 5 wCi/mouse, half-times in liver and kidney
Ogawa, Suzuki and Tsuzuki, 1972, studied the fate of 115mCd after
intraperitoneal injection to mice, the dose being 0.5 yCi.
Radioactivity in whole body and excrements was determined day
after day for different time periods. In one distribution study
5 animals were sacrificed 1, 2, 6 and 24 hours after injection.
The uptake was highest in the liver, Initially, the pancreas
took up more cadmium than did the kidney, but after 24 hours
kidney levels had exceeded the pancreatic levels.
The cadmium distribution after repeated exposure has been
described by Levy et al., 1973. Three groups of rats with 25 animals
in each were given weekly injections subcutaneously of 0.087, 0.044,
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4-11
0.022 mg cadmium as cadmium sulfate for two years. 75 animals
constituted a control group given only water injections. The
animals were killed after 2 years and cadmium determined in
organs. Due to losses of water during storage cadmium concentra-
tions were expressed as yg Cd/g "stored tissue", which makes it
impossible.to compare this with other studies. However, in all
groups the kidney had the highest content of cadmium, followed
by the liver except in the highest exposure group, where the 0?
spleen had a higher concentration of cadmium than the liver.
The accumulation in rabbits ingesting cadmium has been reported
by Nomiyama, 1974. Food containing 300 ng/g of cadmium was given
;l
to a group of rabbits for 1 year. As shown in Figure 4:8 maximum:
levels in renal cortex were reached after about 20 weeks, and *
c<
after 30 weeks there was a decline. In the liver maximum levels
were reached at about 40 weeks of exposure, this organ also
showing a decrease later. Nomiyama reported that these animals
had signs of renal dysfunction at a concentration of about 200
vg/g in renal cortex, i.e. after about 15 weeks (section 5.1.1.2)
The decrease in renal concentrations of cadmium was explained
by Nomiyama as being the result of a decreased ingestion of
cadmium as shown in Figure 4:9. The data will be commented upon
further in section 4.2.3.1. The decreased renal cadmium con-
centrations occurred subsequently to an increased excretion
after renal damage.
Suzuki, 1974, gave rats 0.5 mg/kg body weight subcutaneously
each day except Sunday during 15 weeks. Each week 3-5 animals
were killed and cadmium concentration was analyzed in organs.
Blood and urine samples were collected weekly. Cadmium was
analyzed with atomic absorption directly on the acid solution
after wet ashing. The method will involve errors in analysis
of low-level samples but at the concentrations received in this ;
animal experiment the method may be used. Cadmium concentration I
in kidney increases until the 7th week and then levels off at ^
about 150 yg/g wet weight (Figure 4:10). Liver concentration
increases a little more and then decreases. In the water-
soluble fraction for both kidney and liver about 80% of
cadmium is found. Cadmium concentration in blood increases
-------
4-12
during the whole experiment (Figure 4:11). Nevertheless there
is a great increase in urinary cadmium excretion after about
8 weeks (Figure 4:11). Urine volume and proteinuria had started
an increase somewhat earlier. The data by Suzuki, 1974, speak
in favor of an increased urinary cadmium excretion coinciding with
the occurrence of renal damage and with the levelling off of
cadmium concentration in kidney. In this experiment kidney damage
occurred at a kidney cortex concentration of about 225 vg/g wet
weight (= 1.5 x 150 vg/g).
The distribution of cadmium in lambs given cadmium orally for
191 days has been reported by Doyle et al., 1974. Five groups of
six lambs in each were given diets containing 0, 15, 30 and 60
vg/g. In liver arid kidneys cadmium levels were proportional to
the dose. In kidney cadmium concentrations were on an average
768.8 vg/g dry weight (about 150 vg/g wet weight) in the group
given the highest dose.
Ninety-day studies were performed on rats and dogs by Lorke
and Loser, 1974. Groups of 20 male and female rats were given
0, 1, 3, 10 and 30 yg cadmium (as the chloride) per gram of diet.
Cadmium was determined in liver and kidneys, the highest dose
level resulting in mean levels of cadmium of about 9 and 12 vg/g
wet weight respectively. There was no difference between the
sexes. In the dog study, 2 female and 2 male dogs in each group,
the same concentrations in food were used. Mean levels in liver
and kidneys in the highest exposure groups were about 6 and
16 vg/g wet weight respectively. Cadmium was also determined
in pancreas and salivary glands, being about 0.6 and 0.4 vg
in the highest exposure group. Of interest is that at a lower
exposure (1-3 vg/g diet) the salivary gland contained more than
the pancreas.
Cousins, Barber and Trout, 1973, gave growing swine cadmium in the
diet, the levels being 0, 50, 150, 450, and 1350 vg/g for 6 weeks.
In another experiment 30, 90, 270, and 810 iig/g of diet were
given. In liver the cadmium concentrations increased in proportion
to exposure. Renal concentrations increased to about 275 vg/g
wet weight, and then levelled off as shown in Figure 4:12.
Since renal function and protein excretion were not examined,
it is not known whether tubular dysfunction was present.
-------
4-13
Tanabe (cited by Ishizaki, 1972) followed the fate of cadmium
after cessation of long-term oral exposure. Adult rats were
given cadmium as the chloride in drinking water .(50 yg/g) for 6
months, whereafter the animals were studied for another 9 months.
Every third month during and after exposure 2-4 animals of each
sex were killed and cadmium determined in organs (method not
stated) . Liver levels of cadmium both after 3 and 6 months of
exposure were only about 3 ug/g wet weight and at the end of the
experiment about 2 yg/g wet weight. In kidney the levels were ) ,
about 5 and 8 yg/g wet weight after 3 and 6 months respectively^;
about 10 yg/g the first months after cessation of exposure and
at the end of the experiment a slight decrease was rioted. It
is clearly stated in the paper that the concentration in water
was 50 yg/g but the concentrations in organs are surprisingly
low, since several other experiments described in earlier editions
of CITE and in the present one show considerably higher organ
concentrations at this level of exposure.
4.2.3 Excretion
In CITE, 2nd ed. , it was concluded that urinary excretion of
cadmium was mainly dependent on body burden, before renal damage
had occurred, but that considerably higher excretion could be
caused by renal dysfunction or by extreme exposures.
4.2.3.1
Results from several studies on urinary excretion of cadmium have
been reported by Nomiyama, 1974. In Figure 4:13 the urinary >
excretion of cadmium in rabbits given 300 yg Cd/kg (36 mg of
I
cadmium per day) of diet for one year is shown. Signs of renal
dysfunction in the form of aminoaciduria were reported after about
16 weeks of exposure (corresponding to about 200 yg/g in renal
cortex) and in the form of proteinuria after about 38 weeks
(corresponding to about 300 yg/g in renal cortex) . However,
Nomiyama et al . , in press, revealed that aminoaciduria occurred
in 5 out of 16 determinations between 14 and 52 weeks of exposure
and proteinuria occurred in 5 out of 7 determinations between
34 and 52 weeks of exposure. Nomiyama, 1974, concluded from these
data that there is no increase in excretion of cadmium when renal
dysfunction occurs. If Nomiyama 's data are taken at face value
the urinary excretion (yg Cd/day) does not increase during the
-------
4-14
first 25 weeks after which the volumes on an average are higher.
This increase in excretion coincides with a decrease in liver
and kidney values. However, it is not clear how urine was separated
from feces and the risk for contamination from feces to urine
must have been great (0.1% of fecal cadmium in urine would give
about 35 yg/day). Contamination from food can also occur in
such experiments. Excretion values of about 20 yg/day after only
about 5 weeks of exposure were found at a time when the body
burden was still relatively low, indicating that contamination
could have taken place.
In the paper by Nomiyama, 1974, an experiment is.reported in which
rabbits were given subcutaneous injections of cadmium, 1.5 mg/kg,
daily for 5 weeks. In Figure 4:14 the urinary excretion is shown.
It is obvious that there is a considerable increase in cadmium
excretion in the fourth week of exposure as also seen in the experi-
ment by Suzuki, 1974, described in section 4.2.2 and Figure 4:11.
Nomiyama also followed the excretion of cadmium for 15 weeks
after cessation of exposure (daily subcutaneous injections of
1.5 mg Cd/kg for 3 weeks). Some animals were given repeated
injections of uranylacetate after cessation of exposure which
maintained a renal damage. These animals did not differ from the
other animals with regard to decrease in urinary cadmium, as
shown in Figure 4:15. There were lower cadmium levels in the
kidneys, of uranium treated animals.
Ogawa, Suzuki and Tsuzuki, 1972, gave a single dose of mCdCl2
80.5 yCi (specific activity not stated) to mice intraperito-
neally. In Figure 4:16 it is shown that urinary excretion
after an injected dose is low compared to fecal excretion.
This is in accord with earlier studies. The influence of pre-
treatment with a small dose of cadmium upon urinary excretion
after a larger dose was studied by Yoshikawa, 1973. Two groups
of four male rats each received an intraperitoneal dose of
3 mg Cd/kg as the chloride, one group having received 0.6 mg
Cd/kg intraperitoneally 24 hours earlier. Cadmium in urine
was determined daily for one week by atomic absorption (no
details given), and since the daily excretion was as high as
1.5 pg before injection, there is some doubt about the validity
of the method. On the second day after injection the pre-
treated group excreted on an average about 4 yg of cadmium,
whereas in the non-treated group about 20 yg was excreted. It
-------
4-15
was concluded that the excretion of cadmium was suppressed by
pretreatment .
4.2.3.2 bilancreas, and
Cikrt and Tichy, 1974, studied the excretion of cadmium via
bile. Three groups of female rats with cannulated bile ducts
were given intravenous injections of 67, 90, and 120 yg cadmium .,
as cadmium chloride respectively (about 0.35, 0.45 and 0.60 mg/kg
of body weight) . Bile was collected hourly for 24 hours. In the
three groups 0.83, 1.18 and 5.68% of the given dose was recovered
in the bile during 24 hours, the main part being excreted during
the first two hours after injection. Analysis of gastrointestinal
content and feces showed that both in rats given 67 and 120 yg "
about 5.5% of the given dose had been excreted. In the walls of
*•
the gastrointestinal tract 7.04 and 4.79% of the dose was found.
In another experiment on rats the excretion via bile was followedj
.with 5-minute collections for 80 minutes after the injection of
10 yCi of 115mCd (95 yg) as the chloride. It was found that '
maximum excretion occurred between 15 and 30 minutes after
injection. Electrophoretic separation of the radioactive bile
in polyacrylamide gel revealed that cadmium was in two major
fractions.
Further studies by Havrdova, Cikrt and Tichy, 1974, showed that
when bile from rats given intravenous injections of cadmium
chloride 120 yg Cd/rat, 0.6 mg/kg, was separated by gel filtration
on Sephadex G-100 about half of the cadmium was in a high molecular
weight fraction and the other half in a low molecular weight
fraction. These fractions have not yet been characterized.
Nordberg and Robert, to be published, gave subcutaneous injection
109
of CdCl- (0.5 mg Cd/kg) to 4 rats. During the first hours
after injection the biliary excretion per hour was about 0.04% of
the given dose and after 68 hours a total of 0.29% of the given •
dose had been excreted. Separations by gel filtration showed that
all cadmium was in fractions of very low molecular weight (< 4000).
The differences in injection routes may explain the differences
between the results of Nordberg and Robert, and Havrdova, Cikrt and
Tichy. Nordberg and Robert also studied pancreatic excretion
of cadmium in 4 rats. After 24 hours 0.0044% of the dose on an
average had been excreted via that route .
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4-16
4.2.4 Biological half-time
In CITE, 2nd ed., it was concluded that after a single injection of
cadmium the biological half-time was about 200 days in mice
and rats, 400 days in dogs and 1.5 years in squirrel monkeys.
Moore et al., 1973, determined the biological half-time in
the rat aftei? inhalation (section 4.1.1), ingestion and two
injection routes. The half-time was found to be about 200 days
by all routes, which agrees well with earlier data.
Sayato,Hasegawa and Ando, 1971, estimated the half-time in rats
to be 15.3 days after an oral dose of mCd, but this was only
based on observations during days 3-24 after exposure. They
also gave an intravenous injection of mCd and estimated that
the half-time was 333.7 days after 70 days of observation.
Matsubara-Khan, 1974, gave 40 male and 40 female mice subcutaneous
109
injections of Cd Cl_ and determined activity in organs
£i
in 5 males and 5 females at different intervals for 128 days
(section 4.2.2). The following half-times were obtained: liver:
63 days, kidney:990 days, salivary glands: 433 days. Based on
organ measurements the biological half-time for whole body was
estimated to be 217 days. She also made a study on the fate
of caditlium after oral administration and found the following
half-times: liver: 43 days, kidney 433 days, salivary glands 150
days.
With regard to the injection experiment it has already been
commented (section 4.2.2) that the estimate for half-time in
kidney does not fit with the actual data as shown in Figure 4:7
where a clear decrease is seen in kidney from day 32 to 128. This
seems to indicate a half-time of 300-400 days, which fits with
the results from the oral experiment.
-------
4-17
4.2.5 Interactions between cadmium and other metals or compounds
In CITE, 2nd ed., it was concluded that cadmium metabolism was
intimately related to zinc metabolism. Another metal that had
been shown.to interact with cadmium was selenium. Chelating
agents had been found to influence renal levels of cadmium after
a single injection of cadmium. BAL increased the uptake, whereas
HEDTA and DTPA decreased the uptake of cadmium in kidneys. It had
also been shown that when a mixture of EDTA and cadmium was in- U
jected into rabbits, urinary cadmium excretion increased 1,000-fold,
and organ levels of cadmium were lower than in animals given cadmium
alone. Long-term oral exposure to NTA and cadmium revealed a
tendency for NTA to cause less retention of cadmium.
With regard to zinc further data have been furnished on the rela-
tionship between cadmium and zinc in kidneys. Piscator, 1974, found
an equimolar increase of zinc and cadmium in normal horses in the
same range as earlier found in human beings, i.e. up to about 75
yg/g wet weight in renal cortex. At higher cadmium levels, however,
the increase in zinc did not keep up with the increase in cadmium,
as seen in Figure 4:17, where also results from some other studies
are depicted. These findings indicate that in the range of 100-200
yg cadmium/g wet weight in renal cortex, i.e. below the critical
level, an unfavorable quotient between zinc and cadmium exists,
which may influence e.g. some enzymatic activities.
Cousins, Barber and Trout, 1973, gave growing swine cadmium in
the diet, 0, 50, 150, 450 and 1350 yg/g of diet. Cadmium and
zinc were determined in whole kidney and as seen in Figure 4:17
the increase in zinc was equimolar to the increase in cadmium
at lower exposure levels up to a cadmium concentration of 78 yg/g
wet weight (about 100 yg/g wet weight in renal cortex). Further
increase in cadmium did not cause any further increase in zinc
levels. In other organs there was a tendency for lowering of
the zinc concentrations, most noticeable in the lung.
-------
4-18
Evans, Grace and Hahn, 1974, studied the influence of copper
and cadmium on the metabolism of Zn in zinc-deficient and
zinc-supplemented rats. Seventy-two male rats were fed a zinc-
deficient diet for 13 days. One-half of the animals were zinc-
supplemented by injections for two days. Oral doses of Zn at
three dose levels, 0.065, 0.65 and 6.5 ug were given by gastric
tube to all animals. In each group one third was given
copper and one third was given cadmium (112 vig of Cd as
CdCl9), e.g. the molar ratios of Cd to Zn were 1 000, 100
c c
and 10 respectively. Zn activity was measured in the carcass,
excluding the gastrointestinal tract, and in the small intestine.
In zinc-deficient animals cadmium had no effect on the absorp-
tion of zinc; in zinc-supplemented animals, however, cadmium
decreased the absorption of zinc at all dose levels of zinc
with about 50 %. The .uptake of zinc into the intestinal mucosa
was decreased by cadmium in both zinc-deficient and zinc-
supplemented rats, the decrease being about four-fold.
The results were interpreted as showing two independent pro-
cesses for zinc absorption, one being the transport of zinc
from the intestinal lumen to the carcass, the other being the
uptake of zinc by the intestinal epithelial cells. The authors
could not explain why cadmium (and also copper) did not influence
the absorption into the carcass in zinc-deficient animals, but
inhibited transport in zinc-supplemented ones. They postulated
that the number of available zinc-binding sites in plasma albu-
min might be greater in zinc-deficient animals.
Shank and Vetter, 1974, gave groups of rats intraperitoneally
25 yg Cd/kg of body weight ( CdCl2). Subgroups of 5 were
simultaneously given copper, mercury or zinc at three different
levels. The zinc to cadmium ratios were 50, 100 and 200 respec-
tively (weight by weight). The animals were killed 24 hours
-------
4-19
after injection. Zinc was found to increase cadmium levels in ;
liver as seen.in Figure 4:18 (similar results were obtained with
copper and mercury). It is seen that the uptake of cadmium in
liver is increased about two-fold by the two highest zinc doses.
The authors concluded that the studied metals produced an
.increase in liver levels of .cadmium, suggested as being due to
a stimulation of metallothionein synthesis.
Ogawa, Suzuki and Tsuzuki, 1972, found that the simultaneous
injection of ZnSO. did not cause any change in the distribution
of cadmium in mice given an intraperitoneal injection of Cd.
They also found that mercury caused a substantial decrease in
renal levels of cadmium, but a slight increase in liver levels.
5
Roberts et al., 1973, gave 11 male calves a diet with 8.5 pg/g
of zinc and some of these calves were also given 350 yg Cd/g
of diet for 14 days. After 8 days an oral dose of Zn was given
to all animals and feces and urine collected for 7 days, where-
after the animals were killed. This high exposure to cadmium
decreased the retention of Zn, as shown both by excretion
measurements and tissue analysis. Stable zinc content in tissues
was also determined. Zinc concentrations in liver and kidneys
were higher in cadmium treated animals, the difference not
being statistically different, whereas there was a significant
decrease in muscle zinc.
ii
These data support the above mentioned findings by Evans, Grace
and Hahn, 1974, that cadmium will decrease the absorption of
zinc in zinc-supplemented animals and also confirm earlier fin-
dings that cadmium exposure causes a redistribution of body
zinc.
-------
4-20
The influence of mercury was studied by Suzuki and Yoshikawa,
1971, who gave intraperitoneal injections of 3 mg/kg body
weight of cadmium chloride to groups of rats without and with
mercury pretreatment in a dose of 0.3 mg/kg, 24 hours before
the cadmium injection. Animals were killed 96 hours after the
cadmium injection. It was found that the cadmium content of the
liver was less in animals pretreated with mercury. This result
is in contrast to the results by Ogawa, Suzuki and Tsuzuki, 1972,
but the mercury dose was considerably less.
It has earlier been shown that ascorbic acid influences the toxi-
city of cadmium. Pyridoxine (vitamin B,) was studied by Stowe
b
et al., 1974. Groups of rats were given diets deficient and high
in pyridoxine (two levels) and with and without added cadmium
(100 ug/g diet) for 12 weeks. Pyridoxine supplemented rats had
higher concentrations of cadmium in kidney and liver than pyri-
doxine-deficient animals, and it was also found that increasing
the pyridoxine intake increased the retention of cadmium. Since
pyridoxine also increased the toxic effects of cadmium the
authors concluded that excessive intakes of pyridoxine might
aggravate the effects of cadmium.
Eybl, Sykora and Mertl, 1973, gave mice a single injection intra-
venously of cadmium chloride (0.6 mg Cd/kg). Some animals
were also given simultaneously an intraperitoneal injection of
zinc chloride (8.9 mg Zn/kg). After 24 hours the animals were
killed. There was a tendency to higher Cd-retention in animals
given zinc, but the difference was not statistically significant.
In liver 40.1% of the injected dose was found in the animals
given Cd alone, whereas in zinc-treated animals 35.9% was found.
In kidneys the corresponding figures were 3.3 and 4.0% respec-
-------
4-21
tively. Only in testicles did zinc cause a significant increase
in cadmium concentrations. In another experiment mice were given
an intravenous injection of 0.25 mg Cd/kg as the chloride,
and followed for 21 days. On day 7, 10, 13, 17 and 26 after the
cadmium injection, intraperitoneal doses of 8.1 mg Zn/kg were
given. After 21 days the animals were killed. The whole body
retention of cadmium was slightly higher in animals that had I1
received zinc. Liver retention was slightly lower in zinc-trea-
ted animals, 51.8% compared to 55.9%, and kidney retention was
higher, 9.5% compared to 5.7%.
These results indicate some influence of zinc on cadmium meta- •
. - v
holism in injection experiments. It should be noted that these
results are in contrast to those of Shank and Vetter, 1974. *
0
Eybl, Sykora and Mertl in the same study also tested different
chelating agents under the same experimental conditions. In the
acute experiments CaDTPA and ZnbTPA were found to be the most
effective substances for removal of cadmium. After 24 hours the
retention of cadmium was only about 20 and 30% respectively, of
v
the injected dose, whereas about 80% remained in animals given
only CdCl2.
In the 21-day experiment CaDTPA, ZnEDTA and ZnDTPA caused very
small but significant decreases in whole body retention compared
to day 7, as seen in Figure 4:19. The differences are much smal-
ler than in the acute experiment. In organs the differences
were small, the liver retention being in the range of 50.8-57.5%
in the animals given chelating agents compared to 55.9% in ani-
mals given only Cd; in kidneys the range was 5.3-6.0% compared
to 5.'7%.
-------
4-22
Histological examinations of the kidneys were not made. These
studies confirm that chelating agents may have a dramatic effect
on excretion and distribution of cadmium if given simultaneously,
but that these agents have very little influence on the distri-
bution of cadmium if treatment is begun several days after
cadmium exposure.
In another experiment 112 mg/kg body weight of cadmium as the
chloride was injected subcutaneously into rats. Simultaneously,
the Ca- and Zn-complexes of chelating agents were injected intra-
peritoneally. Urine was collected and after 2 hours the animals
were killed. In urine cadmium complexes were found and charac-
terized.
Dequidt, Haguenoer and Fromont, 1973, gave rats single doses
of cadmium, 2 mg/kg as the sulfate, by injection and then for
7 days different agents, penicillin (30,000 I.U.), BAL (3 mg/kg),
CaN_EDTA (25 mg/animal), penicillamine (50 mg/animal) and
CaNa_DTPA (10 mg/animal).
Penicillin did not cause an increase in urinary excretion of
cadmium, but liver concentrations were only about one fourth
of control levels (21 and 78 Vg/g respectively). In other organs
examined, there were no major differences. Intestinal concentra-
tions were not higher in the treated animals and it is not
clear where cadmium was excreted or stored.
The other drugs examined behaved as expected, i.e. urinary
excretion increased to some extent and liver and renal levels
decreased. The authors concluded that none of these drugs
would be suitable for treatment of cadmium poisoning.
-------
4-23
In studies on selenium toxicity Hill, 1974, found that dietary
levels of 57 yg Cd/g caused a 15% mortality and a level of
40 yg Se/g of diet caused a mortality of 20% in chicks. When
cadmium and selenium were given together at the above concentra-
tions mortality was 21.2%. In controls with no extra selenium or
cadmium, mortality was 2%. Selenium caused growth retardation
and so did cadmium, but together they did not cause more growth
retardation than selenium alone. The only conclusion that can
be drawn from these results is that there is no additive effect.
4.2.6 Conclusions
A vast number of experiments have been performed during the last
years, but the majority have mainly just confirmed earlier
findings. Among new data are those showing that biliary excretion
of cadmium in animals is low. The urinary excretion of cadmium
is still a matter of discussion, but no conclusive evidence
has been presented that would speak against an increased excretion
concurrent to tubular dysfunction. The difficulties in per-
forming long-term feeding experiments with high doses of cadmium
without getting contamination of urine from feces are obvious.
Furthermore there are other studies that show a sharp rise in
urinary excretion of cadmium when damage occurs.
Studies on interaction between cadmium and zinc and other metals
stress the importance of further research in that field.
-------
4-24
4.3 TRANSPORT, DISTRIBUTION AND EXCRETION OF CADMIUM IN
"NORMAL" AND EXPOSED HUMAN BEINGS
4.3.1 Transport and distribution in blood
In CITE,. 2nd ed., it was concluded that the average normal cad-
mium level in whole blood is well below 10 ng/g (1 yg/100 g). In
exposed workers considerably higher values had been reported.
After exposure had ceased, there would be a slow decrease in
blood concentrations. This decrease could, however, be rela-
tively fast after short-term intensive exposure.
During the last years a large number of studies have been per-
formed on "normal" blood concentrations. The results of these
studies are compiled in Table 4:1. Most studies give mean con-
centrations between 1 and 10 ng/g. The lowest values are repor-
ted by Ediger and Coleman, 1973,and Ulander and Axelsson, 1974,
both groups using the Delves' Cup technique. It is noteworthy
that in some studies a separation has been made into smokers
and non-smokers, the former generally having higher blood con-
centrations than the latter.
In all studies atomic absorption has been used with different
procedures or equipment, see also Chapter 2.
Even though the present data strongly support the earlier finding
that "normal" blood levels of cadmium are below 10 ng/g, the
"true" levels are not known yet.
In some of these reports results from cadmium determination in
blood from exposed workers have been included (Cernik and Sayers,
1974; Lauwerys, Buchet and Roels, 1973; Roels et al., 1974;
Lauwerys et al., 1974).Mean values between 10 and 50 ng/g have
been reported for different exposure groups, exposure to cadmium
fumes giving the highest values.
-------
4-25
That the decrease in blood concentrations of cadmium after
long-term low level exposure is very slow is shown in
Figure 4:20 illustrating blood levels in a worker during
exposure and for 4 years after cessation of exposure (Rogenfelt,
personal communication). After high exposure there is a much
more rapid decrease as seen in Figure 4:21. Initially extremely
high blood cadmium concentrations had been recorded.
4.3.2 In organs
Data on concentrations of cadmium in organs have been presented
in CITE, 2nd edr Average liver concentrations of cadmium were
between 1-3 yg/g wet weight in some European countries and in the
U.S., whereas "normal" concentrations in three Japanese areas
were considerably higher, in one area 5-10 times higher than in the
U.S., U.K. and Sweden. In exposed workers and Itai-itai disease
patients cadmium concentrations in liver could reach 100 yg/g
wet weight or even higher.
The highest cadmium concentration was found in the renal cortex,
the "normal" concentration being on an average between 15 and 30
pg/g wet weight at age 50 in some European and American areas.
Smokers generally had higher cadmium levels than non-smokers.
In three areas in Japan, mean normal levels of 50, 90 and 125
yg/g respectively were found at about 50 years of age. In
exposed workers concentrations of about 300 yg/g wet weight had
been reported, but also values within the normal range had been
found despite signs of cadmium intoxication. Losses of cadmium -
due to renal dysfunction were thought to be the cause of these
low values.
-------
4-26
It was calculated that normally about 50% of the total body
burden was stored in liver and kidneys, the kidneys alone con-
taining about one third. At high exposure the liver contained a
larger proportion of the body burden.
Hamilton, Minski and Cleary, 1972/1973, analyzed cadmium in 8
kidneys from accidental deaths in U.K. by X-ray fluorescence.
The mean concentration in renal cortex was 14.3 ^g/g wet weight,
but no data on age are given.
Plantin, 1973, and personal communication, determined cadmium by
neutron activation in liver and renal cortex from 8 cases of sudden
death (age 19-67 years) and in 8 subjects who died from coro-
nary heart disease (age 55-63, mean age 58 years) in Uppsala,
Sweden. If the latter group is compared with 4 cases (age 54-67
years, mean age 58) from the first group, the levels in liver
were 1.8 and 1.0 ng/g wet weight respectively, and in renal cor-
tex 20.1 and 13.3 ng/g wet weight respectively. The values agree
with other data on renal and liver levels in Sweden and Europe
in persons of similar age, but since smoking habits are not
known it is difficult to evaluate the differences in cadmium
levels between the groups.
Vuori, Huunan-Seppala and Kilpio, 1974, determined cadmium in
whole kidney from 20 accident cases (age 13-78 years, mean 35)
in Finland. The average concentration was 73.2 iig/g (S.D. 38.2)
dry weight, which would correspond to about 22 iig/g wet weight
in renal cortex. The mean concentration in liver was 4.15 lig/g
dry weight (about 1.3 pg/g wet weight).
In California, U.S.A., Indraprasit, Alexander and Gonick, 1974,
analyzed for several metals, among them cadmium, in 220 random
hospital autopsies. The patient population was divided into
-------
4-27
three groups, the first one comprising 116 cases called "normal"
with regard to renal function (serum creatinine having been
< 1.5 mg/100 ml). The other two groups were composed of 52
cases of acute renal failure and 52 cases of chronic renal
failure.
Cadmium was analyzed by emission spectrography. In Figure 4:22
cadmium concentrations in renal cortex in the "normal" group
are shown in relation to age. The highest concentrations are
at age 31-60, being on an average 107 |ig/g dry weight (about
21 |ig/g wet weight) . The "normal" group was further divided
into normotensives and hypertensives; the average cadmium con-
centrations were the same in both groups. Liver levels of cad-
mium were on an average 14.4 ug/g dry weight in the "normal"
group (about 4.4 ug/g wet weight). The "normals" in age 31-60
were also compared to the groups of the same age with renal
failure, the latter having significantly lower cadmium and zinc
concentrations.
In Denmark Ostergaard and Clausen, 1974, determined cadmium
in kidneys from 30 autopsied persons from 0-85 years of age.
In age groups 40-49, 50-59 and 60-68 mean renal cortex levels
were 38 (n = 4) , 33 (n = 5) and 35 (n = 7) V!g/g wet weight
respectively. These concentrations are slightly higher than
earlier reported from neighboring countries.
Hirst et'al., 1973, compared 12 autopsy cases with a history
of emphysema (age 48-83 years) with a matched control group
(48-87 years). The mean renal levels of cadmium were 3,000
and 1,700 ug/g ash respectively. Corresponding levels for liver
and lung were 230 and 63, and 83 and 19 l!g/g ash respectively.
Both groups were" mainly composed of smokers, but in the emphy-
sema group there were more heavy smokers. The authors conclu-
ded that smoking was the main cause of the differences in
tissue levels of cadmium.
-------
4-28
McKenzie, 1974, studied the cadmium, zinc and copper content in
autopsies from New Zealand. 7 persons had died from hypertensive
disease, 5 from neoplastic disease and the remaining 7 from other
diseases. There were no statistically significant differences
between cadmium concentration in liver, kidney, lung or pancreas
depending on type of disease or smoking habits. The 6 persons in
the 40-60 years age group had an average kidney (probably total)
concentration of 220 yg Cd/g dry weight. According to the author
the mean water content of the kidneys was 85% for all 19 cases.
On a wet weight basis the cadmium concentration in the 6 persons
will be 33 Pg/g. The corresponding kidney cortex- concentration
would be about 50 yg Cd/g wet weight (x 1.5) , which is slightly
higher than in corresponding age groups in Europe and the U.S.
4.3.3 Excretion
4.3.3.1
The normal urinary excretion of cadmium is low, around 2 yg/day
or less. Under moderate exposure a relationship between body
burden of cadmium and urinary excretion will be upheld. In exposed
workers urinary excretion may vary within large limits, depending
on actual exposure, body burden and renal function.
In Table 4:2 data are compiled from some recent studies on normal
excretion of cadmium. In CITE, 2nd ed., several examples were given
of studies where inaccurate methods were involved. Even though
most reports now present results which seem to be relatively accu-
rate there are still some deviating data. In these studies true
account has not been taken of the interference which may occur in
the determination of urine cadmium with atomic absorption.
Of special interest are the studies from Belgium, where the
studied groups were separated into smokers and non-smokers .
Smokers had higher urine cadmium than non-smokers, which agrees
with the fact that smokers have higher body burdens .
Variations in daily urinary excretion of cadmium were studied by
Taguchi et al., 1972. Five men collected urines for 5 days and
cadmium was determined by atomic absorption after chelation and
extraction into an organic solvent. In Table 4:3 mean values
and variation coefficients are shown. In Figure 4:23 daily urinary
excretion of cadmium is shown in relation to smoking habits.
-------
4-29
Urine excretion in cadmium workers has been studied by several
authors (Cernik and Sayers, 1974; Lauwerys , Buchet and Roels,
1973; Lauwerys et al., 1974; Roels et al . , 1974; Piscator, un-
published data). Cernik and Sayers, 1974, reported on groups of
workers, exposed to cadmium oxide dust and fumes respectively, the
latter excreting considerably larger quantities of cadmium.
In the former group cadmium could not be detected in 8 out of 14
workers, in the remaining six concentrations from 3.9 to 47 ^g/1
were found. In 8 workers exposed to cadmium fumes the concentra-
tions ranged from 9.7 to 75 yg/1, on an average 29 yg/1.
In Figure 4:21 the decrease of urine levels of cadmium after
exposure has ceased is shown in 5 workers, who for a short period
were exposed to large amounts of cadmium (Piscator, unpublished
data) . There were no signs of renal damage in 4 cases, whereas in
the fifth there was a suspicion of a slight tubular dysfunction.
The decrease in urine parallels the decrease in blood levels.
The new data confirm that the normal excretion of cadmium is
low. Smoking has been shown to cause higher excretion of cad-
mium and since it also has been shown that smoking causes in-
creases in body burden of cadmium, it is conceivable that the
higher urine excretion reflects differences in body burden.
4.3.3.2
It was mentioned in earlier reports that cadmium could be found
in human hair with concentrations generally below 1 y
-------
4-30
a mean value of 0.54 yg/g was reported in 17 males in a rural area
in Yugoslavia. In the study of Stankovic et al. 1% nitric acid
was used for washing the hair, which may have influenced the
results.
Vuori, Huunan-Seppala and Kilpio, 1974, determined cadmium in
hair from 20 lethal accident cases in Finland and found a mean
concentration of 0.35 pg/g. In U.S.A. Petering, Yeager and
Witherup, 1973, determined cadmium in hair from 95 men and 83
women in Cincinnati. In males there was an increase from about
1 yg/g at age 2-3 to about 2 yg/g at age 6, whereafter the
level was about the same, until after age 20, when a decrease
appeared. In females cadmium concentrations increased from
about 1 yg/g at age 15 to about 2 yg/g at 30-40 years of age,
whereafter there was a decrease.
A total of 652 hair samples from 200 persons were analyzed in
a study in Houston, Texas (Johnson et al., 1974). There were
three exposed groups, policemen, garage attendants, and women
living near a freeway, each group having a control group. From
each participant 3 or 4 hair samples generally were obtained.
Mean hair cadmium concentrations in the six groups varied from
0.6-2.2 yg/g, the highest values being found in the control
group for the garage attendants, and the lowest in the two
female groups.
What is noteworthy is that in the recent papers just as in those
reviewed in CITE, 2nd ed., there is a discrepancy between results
obtained in the U.S. and in other areas. Mean values around 2 yg/g
have repeatedly been found in adults in U.S.A., whereas in Europe
mean values around 0".5 yg/g are generally found. Since there are
no major differences in liver or renal levels of cadmium, and
the analytical methods are similar, this discrepancy is sur-
prising. In Japan lower hair concentrations have been found than
in U.S.A. (Tsuchiya, Petering and Kobayashi, 1971).
-------
4-31
4.3.4 Conclusions
Extensive studies on the occurrence of cadmium in blood have
confirmed that the normal level is well below 10 ng/g. It has
now also been possible to show differences between smokers and
non-smokers of the same age, thus emphasizing the importance
of cadmium inhaled from cigarettes.
i
i)
Several new data have been obtained on cadmium concentrations
in organs in "normal" populations. Data from U.S., U.K., Sweden,
Denmark and Finland confirm that mean levels in adults may
generally vary from about 15 to about 30 yg/g wet weight of
renal cortex. In some studies the materials have been divided
into smokers and non-smokers, the latter having considerably
less cadmium in liver and kidneys.
With regard to daily urinary excretion of cadmium new data verify
that "normal" excretion is around 1 yg/1 or less in adult popula-
tions in Europe and U.S.A. Workers without direct exposure to
cadmium, but living in the vicinity of cadmium emitting
industries, had between 1 and 2 yg/1 urine. Smokers were found
to excrete more cadmium.
Earlier data on body burden and renal burden have been confirmed
by the new data on organ concentrations. Since organ concentra-
tions and urine concentrations are higher in smokers than non-
smokers this gives further evidence that the urinary excretion
is dependent on body burden.
There are no new data on biological half-time in human beings.
4.4 METALLOTHIONEIN: OCCURRENCE AND PROPERTIES
A review of previously published data on metallothionein has
been given in CITE 2 nd ed., and v/ill not be repeated here.
During the last years the following additional data have been
published:
-------
4-32
dition to those of Biihler 1973, mentioned previously (CITE
2nd ed.). Buhler and Kagi, 1974, isolated two forms of metal-
lothionein from human liver by means of precipitation and
chromatographic procedures including final separation of the
two forms by DEAE ion exchange chromatography. The two forms
had a metal content of 6.53 (Zn: 6.26; Cd: 0.14; Cu: 0.13)
and 7.84 (Zn: 7.58; Cd: 0.19; Cu: 0.07) percent (referring to
the metal-free protein) and a similar amino acid composition
with about 20 residues of cysteine and no aromatic ones in a
minimum molecular weight of 6100.
The molecular weight was further studied on performic acid
oxidized metallothionein by gel filtration in 6 M guanidinium
Hci QI Biogel A-5 m. This procedure gave a molecular weight
of 6500 in relation to appropriate marker substances. These
results are in accord with earlier reports by Nordberg et al.
1972, who found a similar molecular weight of metallothionein
from rabbit liver.
Nordberg, Trojanowska and Nordberg, 1974, studied metal binding
proteins from rabbit kidney. They found that the protein
isolated from cadmium exposed animals had isoelectric properties
similar to metallothionein previously isolated from rabbit
liver (Nordberg et al., 1972). A mercury binding protein was
also found which eluted on G-75 sephadex at the same place as
metallothionein. However there was a markedly different iso-
electric point of this protein. The authors also showed that
mercury metallothionein prepared in vitro had different UV-
spectrum than Cd/Zn containing metallothionein.
Studies on rat liver metallothionein relating partly to the
mercury binding properties of the protein have been performed
by Weser et al., 1972, 1973, and Rupp, Voelter and Weser, 1974,
and particularly by Sokolowski, Pilz and Weser, 1974. These
authors focused" on the binding properties of the SH-groups
in metallothionein.
-------
4-33
By employing metailothionein with various metals bound to it
(Zn , Cd or Hg ), and X-ray photoelectron spectroscopy
2+
they observed that the complete displacement of Zn and or
2+ • 2+
Cd by Hg results in a different energy of the binding
electrons of the sulfur of the thiol group compared to the
binding of zinc or cadmium.
Purification of rat liver and kidney metailothionein has been,1:
reported by Kimura et al., 1974. Their preparations, both from
kidney and liver/ had a high cysteine content," but contained
small amounts of phenylalanine.
EgUine hepatic and renal metailothionein has been further
characterized by Kagi et al., 1974. These authors also found
that their metailothionein had a molecular weight of 6500. These
authors found a similar amino acid composition of the protein
from both liver and kidney with a cysteine content of 19-20
residues per molecule. The metal composition was different
in the two organs, zinc being the dominant metal in liver
metailothionein and cadmium and zinc being present in almost
equal molar amounts in the renal protein.
Isolation and identification of metailothionein from mice
have been reported by Nordberg and Nordberg, 1973. Such a
protein from the livers of mice has been further purified
and characterized by Nordberg , M. (to be published) . This
protein too had a high cysteine content, no aromatic acids
and a molecular weight of about 6000.
The role of metallothionein-like proteins in animal nutrition
has been reviewed by Bremner and Davies, 1973. Bremner and
Marshall, 1974, and Bremner and Davies, 1974, studied the
distribution of copper and zinc among soluble proteins of
livers from calves and sheep of different Cu and Zn status
2+
and from rats injected with Cu . They found that the distribu-
tion of metals between these fractions was variable and
dependent on both Cu and Zn status. In a following paper
-------
4-34
the authors further characterized the low molecular weight
fractions from calf liver and showed that this protein, which
had mainly zinc bound to it, had an amino acid composition
similar to what has been reported for metallothionein.
Davies, Bremner, and Mills, 1973, and Bremner, Davies, and Mills,
1973, have reported that injection of zinc salt into rats
induces the synthesis of a low molecular weight zinc binding
protein in the liver and that food restriction, another means
of increasing liver zinc concentration,also results in the
appearance of this protein.
Studies on the appearance of a zinc-binding protein in rat
pancreas have been performed by Davies and Bremner, 1974.
This protein was found on gelchromatography to have a
molecular weight similar to metallothionein.
The possibility of induction of metallothionein synthesis by
various metal salts has further been studied by Sabbioni and
Marafante, 1975, who could not find such induction by any
metals other than cadmium.
Squibb and Cousins, 1974, have shown that metallothionein
(cadmium binding protein) is synthesized in th«t liver de novo
in response to injection of cadmium to rats. This reaction
could be inhibited by known inhibitors of protein synthesis
like actinomycin D.
-------
TABLE 4:1
"NORMAL" LEVELS OF CADMIUM IN BLOOD yg/.10(
Sex
M
M
M
M
F
F
(S)
(S)
(NS)
(S)
(NS)
M+F
M
M
F
F
(S)
(NS)
(S)
(NS)
M+F
M
M+F
M
M
F
F
(S)
(NS)
(NS)
(NS)
Country n
Belgium 22
110
33
11
14
15
Denmark * 110
U.K. 9
10
8
8
West Ger-
many 37
USA 50
60
U.K. 10
Sweden 2 5
19
20
25
Age
51±7
48±10
31±14
30±7
28±9
0-80
Adults
II
II
II
II
"
12
20-55
20-55
20-55
20-55
mean, S.D,
7
5
7
7
12
8
12
23
20
24
19
9
0
0
4
2
0
2
0
.oii.o
.8-2.1
.0-6.0;
.0-3.0
.0-15.:0
.0±18.0 '
.6
.2±5.7
.6-4.4
.4-1.9
.7-1.9
.5
.6
. 5 (medial
.0
.3
.6 '
.0
.5
range
5.0-45.0
15.0-28.5
11.0-28.0
21.0-27.0
16.0-22.8
4.0-19.0
0.2-2..0
2.0-8.0
0.6-6.1
0.3-1.2
0.5-7.6
0.2-1.0
(METHOD: ATOMIC ABSORPTION) .
special procedure Reference
extraction
Graphite atomizer
Delves cup
Delves Cup
with backgr corr
Lauwerys et al., 1974
Roels et al., 1974
Lauwerys, Buchet and
Roels, .1973
Nygaard, Bo"nde and
Hansen, 1974
Willden, 1973
Stoeppler et al., 1974
Ediger and Coleman, 1973
Ulander and Axelson, 1974
-------
TABLE 4:2
URINARY EXCRETION OF CADMIUM IN "NORMAL" SUBJECTS. METHODS: ATOMIC ABSORPTION
Sex
M (S)XX
M (NS)XX
F (S)XX
F (NS)XX
M (NS)
W
MXX
Not re-
ported xx
M
M
F
M+F
Country
Belgium
Belgium
Belgium
Belgium
Belgium
Belgium
Japan
Japan
Japan
New Zealand
U.K.
U.S.A.
U.S.A.
n age
33 48±10
11 31±14
14 30± 7
15 28± 9
20
110
81 20-60
5 27-37
V W
374 20-60
106 43± 8
10 Adults
20
13
mean, S.D. range
2.011.2
1.0±0.7
2.6±3.0
1.5±2.0
0.38±0.4
1.79±1.68
1.39 0.25-4
2.56X 1.7-3.7X
0.64+0.65 0.05-3.68
-0.33
(geometric
mean)
1.06+1.06 0.24-6.72
-0.53
(geometric
mean)
23±21
44.8±12.4
1.5±0.7 0.4-3.7
2.9 0-10.1
unit special
procedure
yg/g crea- extraction
tinine
yg/g crea- "
tinine
yg/g crea-
tinine
yg/g crea- "
tinine
.
n
yg/i
yg/day
yg/l (adjusted
individually
for spec. grav. )
yg/24 hr
yg/24 h
yg/day
yg/l graphite atomi-
zer
yg/day extraction
Carbon Rod
Atomizer
Reference
Lauwerys, Buchet
and Roels, 1973
Lauwerys, Buchet
and Roels, 1973
Lauwerys, Buchet
and Roels, 1973
Lauwerys , Buchet
and Roels, 1973
Lauwerys , Buchet
and Roels, 1973
Roels et al .
1974
Tada, Nakaaki and
Fukabori, 1972
Taguchi et al. ,
1972
Fukabori and ;
Nakaaki, 1974
Fukabori and
Nakaaki, 1974
McKenzie and Kay,
1973
Willden, 1973
Ross and Gonzales,
1974
Kubasik and Volosin,
1973
Mean of 5 days
xxWorkers without direct exposure to metals
xxx
Including the 81 from Tada, Nakaaki
and Fukabori, 1972.
-------
TABLE 4:3
URINARY EXCRETION OF CADMIUM IN 5 SUBJECTS DURING 5 DAYS. (From Taguchi et al., 1972)
Case No.
1
2
3
4
5
Age
33
-33
.- 31
37
'••; 27
Smoking
cigarettes/day
t
0
20 'V
15 1
25 •
10 \.
Cadmium
yg/day
1.66±0.71
2.54+0.79
2.58±1.47
3.71±1.56
2.29±0.87
Coefficient
of variation
0.43
0.31
0.57 . *
0.42
0.38
Cadmium
yg/i
2.14
1.93
1.88
2.80
1.94
Coefficient
of variation
0.53
0.21
0.36
0.24
0.31
-------
4-38
Whole body
retention,
% of initial dose
70
60
50
40
30
dO
*
J
I
E\
-- -I ' •• .-
• Inhalation
\
0 .
Oral
10 20
Days, after dosing
i//,.
FIGURE 4:1 Whole-body retention of 5Cd following a
single exposure by different routes of
administration (From Moore et al./ 1973).
-------
4-39
0
50
100%
Remained
^ . •' '
Feces & Urine 88
1 2
1
.-- •^.'V'f.a
^-" /
^^ /
Stomacjj.
Large Int. >.
Others
| Duod.
Small Int. |
G.I. Tracts & Cont .
Kid.
13.4
Liver
21. 8
9.2
55.6
Skin & Hair 5.1
Muscle 8
5a
•7-| I
Kidney
30.1
Liver
49.3
Adrenal glands 1,4 —
Others 5.4 —
J
FIGURE 4:2
Absorption rate and organ distribution of
109
cadmium after a single oral dose of Cd
to a monkey, Macaca irus. After 19 days
(From Suzuki, Taguchi and Yokohashi, 1974).
-------
4-40
--"A
0123
A = intravenous injection
B = 7 days of age
C=14 -••-
D = 21 -••-
E = adult
21 days after exposure
FIGURE 4:3 Whole-body retention after a single peroral
exposure to ' mcd In mice of different ages
(From Matsusaka et al., 1972).
-------
4-41
% whole body
retention
100
6 days after
administration
FIGURE 4:4
Retention of mCd in a man after oral
administration (From Yamagata, Iwashima
and Nagai, 1974).
-------
4-42
80
70
60
50
40
30
20
10
0
RED BLOOD
CELL
6 24 72
HOURS AFTER INJECTION
Cd-Cd Cd
168
FIGURE 4:5
Changes of cadmium concentration in whole blood/
red cells, and plasma after two exposure conditions
in rats (continuous lines = pretreatment with 0.6
mg of cadmium/kg body weight prior to an i.p. in-
jection of 3 mg Cd/kg. Dashed lines = rats given
i.p. 3 mg cadmium/kg body weight/ no pretreatment) .
(From Yoshikawa, 1973) .
-------
X104 CMP/g
0.3|
t t
4-43
1248 16 32
128 days
109
FIGURE 4:6 Blood levels of Cd after a single subcutaneous
injection (From Matsubara-Khan, 1974).
• individual values
<•> average values
-------
4-44
X1(T
CPM/g
1248 16 32
128 days
109
FIGURE 4:7 Renal levels of Cd after a single subcutaneous
injection (From Matsubara-Khan, 1974).
• individual values
o average values
-------
4-45
Concentration
Cd
300
200-
100-
10 20 30 40 50 60
administration in weeks
A: renal cortex •
B: liver x
C: renal medulla < '
D: liver + kidneys •
E ; kidneys '">
FIGURE 4:8 Cadmium in organs of rabbits orally administered
300 yg/g of cadmium (From Nomiyama/ 1974).
-------
4-46
A B
/ug/day mg
60-
50-
40-
30-
20-
10
0-
10
8-
6-
4
2
0
C
mg/day
5i
4-
3-
2-
1-
0
/>•
/ /
/ /
f /
//
0
!0 20 30 40 50 administration
in weeks
A: Cd in urine
B: kidneys
C: Cd ingested
FIGURE 4:9
Relation between cadmium exposure and cadmium content
in urine and kidneys of rabbits exposed to 300 yg
Cd/g in food (From Nomiyama, 1974). Note: In the
paper by Nomiyama, 1974, the intake at the beginning
of the exposure was stated as 36 mg/day which is
not consistent with his own data in this figure.
-------
4-47
0
A: liver
g: water-soluble
C: kidney
D: water-soluble
i—I
15 weeks
FIGURE 4:10 Total cadmium concentration in liver and kidney
as well as in water-soluble fraction (protein-
bound + ionized) of these two organs in relation
to period of exposure (From Suzuki, 1974).
-------
4-48
Cd
wg
i
2-,
1 -
0
10
Blood
15
1001
50-
Cd exposed
Control
15 weeks
• •Cadmium, /ug/24h
x x proteinuria, mg/24h
urine volume, ml
FIGURE 4:11 Cadmium in blood and urine as well as urine
volume and proteinuria in relation to period
of exposure. Average of 3 '(blood) and 5 (urine)
rats (From Suzuki 1974).
-------
4-49
Kidney cadmium
AJg/g
300 -i
200-
100-
500
1000
1500 dietary cadmium
W9
FIGURE 4:12
Regression of kidney cadmium concentration on
dietary cadmium level. Means - 95% confidence
limits. Data from two experiments are included.
The number of animals represented by each point
are 4,4,4,4,4,3,4,4, and 3 for the 0,30,50,90,
150,270, 450, 810, and 1,350 yg/g Cd groups,
respectively (From Cousins, Barber and Trout,
1973) . Note: The cadmium concentration in kidney
at 0-exposure was not given by these authors
in their figure.
-------
4-50
O
o
o
10 20 30 40 50 60 administration
20 -
in weeks
FIGURE 4:13 Excretion of cadmium in the urine of rabbits,
orally administered 36 mg Cd/day (From
Nomiyama, 1974) .
-------
4-51
% Cd administered
5 administration
in weeks
% Cd absorbed
100-
80-
60-
40-
20-
0
O
1
o - -o
urine
kidneys + urine
feces
liver + feces
5 administration
in weeks
FIGURE 4:14 Percentage cadmium amount in urine and
feces in relation to cadmium amount
administered (above) absorbed into organs
(below) (From Nomiyama, 1974).
-------
4-52
Cd in urine
pg/day
1000
100-
50-
10-
Cd in feces
Mg/day
500n
100J
V
O o uranium arid cadmium exposed
• •cadmium exposed
10 15 20 25 30 weeks
FIGURE 4:15 Excretion of cadmium in urine and feces after
discontinuation of cadmium administration (From
Nomiyama, 1974).
-------
4-53
Total
IOOO
500
0 '2345678
9 10 I I 12 Days
FIGURE 4:16
Excretion of mCdCl_ from mice (From Ogawa,
z*
Suzuki, and Tsuzuki, 1972). Note: In their
text, these authors stated that the daily
excretion was shown in this figure. However,
it is obvious that what is in fact depicted is
the accumulated excretion.
-------
4-54
Zn yumol/g dry weight
7i
HIB
0 1
3 4] 5 6
100/ug/g
wet weight
7 8 ( 9 10 11 Cd /umol/g dry weight
200 pg/g
wet weight
FIGURE 4:17
Regression lines for cadmium and zinc in
renal cortex (From Piscator, 1974) .
I Normal human beings/ age 6-50 years/ n = 36
(prom Piscator and Lind, 1972) .
II Normal human beings/ age 10-90 years, n = 87
(From Hammer et al., 1973).
Ill Normal horses with A: cadmium concentration
below 2.5 ymol/g, n = 20 and B: above 2.5
ymol/g, n = 17 (From Piscator/ 1972).
IV Experimentally exposed swine/ n = 12/
whole kidney (From Cousins/ Barber and
Trout, 1973).
-------
4-55
Concentration
/ug Cd/g tissue
0.40-
0.30
0.20-
0.10 _
~50 100
Metal Ratio Zn/Cd
Liver
Kidney
200
FIGURE 4:18 Influence of zinc on cadmium uptake
(From Shank and Vetter, 1974).
-------
4-56
50-
0
rih
f]
ft
T
1
rt
rt
rt
ft
CdClg CdCl2 CdCl2 CdClg CdClg CdClg CdCl2 CdCl2 CdCl2
ZnCl CaADTA ZnADTA CaCDTA ZnCDTA CaDTPA ZnDTFH Z^DTFA
FIGURE 4:19
Influence of chelating agents on the whole
body cadmium retention in mice in a subacute
experiment. % = retention day 21 divided by
day 7 (From Eybl, Sykora and Mertl, 1974) .
-------
4-57
ngCd/g blood
100—I
^100
1968 1969
Exposure
Transfer
A 197°
I Noexposun
I I
1971
1972
1973
FIGURE 4:20
Cadmium concentrations in blood from a worker
during and after exposure to cadmium oxide
fumes (spectrographic method) (From Rogenfeldt,
personal communication).
-------
4-58
Cd
blood
creatinine in urine
80
70
60-
50
40-
30-
20-
10-
5-
O -O blood
urine
0 24 6 8 10 12 14 16 18 20 months after
cessation of exposure
FIGURE 4:21
Cadmium concentrations in blood and urine
after cessation of exposure in five workers
with previous high exposure to cadmium
(From Piscator/ unpublished data).
-------
4-59
Cd
*9
120-
100-
80-
60-
40-
20-
10-1
12
n=116
80 age interval
FIGURE 4:22
Relationship of kidney cortex content of cadmium
to age.
Plotted are means : S.E.
Similar age relationships were noted for kidney
cortex content of zinc/ copper, lead and
aluminum (From Indraprasit, Alexander and
Gonick, 1974) .
-------
4-60
Cd
• /jg/d/kg
0.08 T
0.06-
0.04-
0.02-
o
o
o
Cd
o
o
r-4
-3
-2
-1
-0
0 10 15 20 25
No. of cigarettes /day
FIGURE 4:23 The average urinary excretion of cadmium for
5 days in 5 persons in relation to smoking
habits (From Taguchi et al., 1972).
-------
5-1
CHAPTER 5. EFFECTS
In CITE, 2nd ed., it was concluded that inhalation of high
concentrations of cadmium compounds can give rise to severe,
often fatal, pneumonitis, as shown both among human beings
and animals. The estimated fatal dose for human beings was
about 2,500 min. x mg/m (corresponding to about 5 mg/m for
8 hours). Acute effects among human beings after gastrointes-
tinal exposure were also described. In animals the acute effects
reported were studied mainly by injection of cadmium. Most
organ systems could be involved, and the effects reviewed
in CITE, 2nd ed. , included hypertension and damage to the
testicles, liver and kidney. The dose varied between 1-20
mg Cd/kg. Results as to acute effects show that cadmium is
an extremely toxic metal, but they have only limited bearing
with regard to the effects produced by long-term exposure.
Long-term inhalation of cadmium compounds can give rise to
chronic pulmonary disorders, especially emphysema. It was
concluded that cadmium oxide fumes may be more dangerous
than cadmium oxide dust. A prolonged industrial exposure to
well below 0.1 mg/m as fume;
with reference to emphysema.
well below 0.1 mg/m as fumes may be considered hazardous
Renal tubular damage has been shown as a chronic systemic
effect of cadmium exposure, regardless of the route of
exposure. The characteristic sign of the renal dysfunction
is proteinuria of the so-called tubular type. This was con-
sidered to be due to decreased tubular absorption of filtered
proteins. As cadmium seems to be transported to the kidney
with a low molecular weight protein, metallothionein, the de-
creased reabsorption of this protein is thought to cause
increased excretion of cadmium in connection with the renal
damage. Other signs of renal tubular dysfunction in cadmium
exposure are glucosuria, aminoaciduria and changes in the
metabolism of calcium and phosphorus . It was concluded in
-------
5-2
CITE, 2nd ed., that the critical concentration in the renal
cortex for the development of tubular proteinuria was about
200. ug/g wet weight. In calcium deficient animals indica-
tions that the critical concentration might be even lower
were pointed out.
Epidemiological studies in Japan have shown an increased
prevalence of proteinuria in the areas most polluted with
cadmium. It was concluded in CITE, 2nd ed., that cadmium
played a causal role in renal tubular dysfunction in persons
living in such areas.
Cadmium may cause a disturbance in calcium and phosphorus
metabolism and osteomalacia has been observed in workers
industrially exposed to cadmium. Animal experiments have
shown demineralization of bone after cadmium exposure. In
one highly cadmium-polluted area of Japan, renal tubular
dysfunction combined with osteomalacia or severe osteopo-
rosis had occurred endemically during the 1940's and the
1950's. The disease was called Itai-itai disease and in CITE,
2nd ed., it was concluded that there was no doubt that the
disease was an expression of chronic cadmium poisoning. De-
ficient consumption of certain essential food elements
and vitamins had been a contributing factor in the etiology,
however.
Other chronic systemic effects found in animals and dealt
with in the rundown of the cadmium literature given in
CITE, 2nd ed., were hypertension, anemia, liver dysfunction,
testicular changes and teratogenic effects. It was concluded
that more data would be necessary to evaluate the yet unknown
significance of these findings for human beings.
Studies have shown that cadmium and cadmium compounds could
give rise to malignant tumors in rats at the site of injec-
tion. It was put forward in CITE, 2nd ed., that the data
-------
5-3
on carcinogenic and genetic effects were by no means con-
clusive and.that further studies were necessary.
In the following treatise a strict division of the effects
according to type has not been set up. Instead, a division
has been made into studies on animals, highly exposed groups
and general population. These divisions have been considered
appropriate because many of the studies to be presented here
confirm the earlier reported effects. In CITE, 2nd ed., studies
in polluted areas in Japan were treated in detail in a separate
chapter but here the new findings will be intermingled with
other data on effects. Only new data of particular interest
regarding these Japanese areas or the etiology of Itai-itai
disease have been included.
We have emphasized effects on calcium- and vitamin-D metabolism,
on the cardiovascular system and on testicles as well as terato-
genic effects because these are matters on which original data
are presently accumulating.
5.1 RESPIRATORY, RENAL, LIVER AND BONE EFFECTS
5.1.1 Studies on animals
5.1.1.1 Acute exp_osure_
Snider et al., 1973, exposed rats one hour a day for 5-15
days to a cadmium chloride aerosol with a mass median diameter
of 4.5 micron and a concentration of 10 mg/m . The animals
developed acute pulmonary symptoms including alveolar hemor-
rhage. Ten days after exposure the changes had transformed into
changes resembling human centrilobular emphysema. The
results confirm earlier data on the high toxicity of inhaled
cadmium aerosols as referred to in CITE, 2nd ed.
5.1.1.2 Prolonged e_xp_osur_e_
Early signs of cadmium intoxication were studied by Nomiyama,
Sato and Yamamoto, 1973, in rabbits given 1.5-15 mg Cd/k'g
-------
5-4
body weight per day up to 45 days for the lowest dose.
Several of the animals died during the experiments. The
authors calculated the median lethal dose of cadmium to be
40-44 mg Cd/kg body weight. By means of stop-flow analyses
in animals exposed to 6 mg/kg/day the authors found signs of
renal tubular as well as glomerular damage. In the experiments
with 1.5 mg Cd/kg/day the earliest sign of intoxication was
an increased excretion of phosphatase in the urine/ appearing
earlier than the proteinuria.
Chronic cadmium poisoning in rats has been studied by Kawai
and Fukuda, 1974/ and Kawai, Fukuda and Kimura, 1974. Six
groups of five male rats in each were given cadmium ad libitum
in drinking water. One group (control group) received only
tap water with no additional cadmium and four groups received
10, 50, 100 and 200 ug cadmium respectively in tap water and
were studied during eight and one-half months. The sixth group
received the dose of 200 ug/g cadmium in tap water but was
studied longer, for 18 months. The results are summarized
in Table 5:1 where it can be seen that the cadmium concentra-
tion in liver is increasing more or less linearly in relation
to the total dose given. On the other hand cadmium concentra-
tion in kidney increases in five of the groups, including
the one given 200 ug/g for eight and one-half months, but
in the sixth group, followed for 18 months, a slight decrease
is witnessed. This decrease is not statistically significant
(Kawai, Fukuda and Kimura, 1974). According to the authors
typical lesions of tubular atrophy with interstitial edema
were found in the kidneys of the groups given 100 ug/g
cadmium or more. Already at the dose level 50 ug/g slight
lesions appeared in some of the animals. This low dose
corresponded to an average kidney concentration of 38.4
Ug/g which would correspond to a kidney cortex concen-
tration of about 57 U9/9 (see CITE, 2nd ed.). In the group
in which typical tubular pathological findings occurred in
-------
5-5
all animals, the corresponding cadmium concentration in kid-
ney cortex was about 150 ug/g. Decalcification and cortical
atrophy of the femur occurred in the animals, these injuries
being indicated in Table 5:1 by the decreasing cortical thick-
ness in percent of the total femoral thickness. The calcium
content also decreased at the dose level 200 ug/g in water.
Histological findings in the bones were reported already
in the group given 50 ug/g cadmium in drinking water.
Other types of effects were a widespread atrophy of exocrine
parenchymal cells in pancreas in the rats given 200 ug/g in
water. There was also some increase of the Kupffer cells in
the liver at the dose levels 100 ug/g and above in water. The
authors concluded that bone might be the most sensitive organ
\
at this early stage of cadmium intoxication. A comparison of
the histological findings in the kidney and the cadmium con-
centration supports the theory that cadmium excretion from the
kidney will increase when the kidney damage is sufficiently
severe.
Bone changes were found by Itokawa et al., 1974, who claimed
that the changes were similar to osteomalacia in humans. Four
groups of five rats in each were given the following diets
and water:
Group 1: calcium adequate diet and distilled water (control group),
Group 2: calcium deficient diet and distilled water,
Group 3: calcium adequate diet and water containing 50 ug Cd/g, and
Group 4: calcium deficient diet and water containing 50 u.g Cd/g.
Diet and water were provided ad libitum. The animals were studied
for 120 days after which they were killed and blood and organ
specimens were taken. Urine was sampled after 112 days.
The growth curves for groups 1 and 2 are very similar whereas
those for group 3, and still more group 4, were significantly
lower. Urinary calcium and phosphorus levels as well as red
-------
5-6
blood cell counts, hematocrit and hemoglobin values were
significantly reduced in the cadmium treated groups.
The tissues of groups 3 and 4 showed hypertrophy and whitish-
-yellow color changes. A considerable degeneration of the kid-
neys occurred in these two groups. The greater part of the tubular
epithelia was desquamated and vacuolized. However, necrosis
and partial hyalinization in the glomerular capillaries and
adhesions between the Bowman capsule and glomerular capillaries
were also observed. Thinning of the cortical osseous tissue
was seen in the bones of the calcium deficient rats. In the
cadmium treated rats, fat deposition took place in the femoral
spongiosa. In group 4, which underwent both calcium deficiency
and cadmium exposure, there were also some osteoid borders on
the bone trabeculae and an increased number of osteocytes in
the cortical tissue. Itokawa et al., 1974, concluded that the
bone findings were similar to the osteomalacia characterized
by poor calcification as seen in humans.
A more subacute experiment, on rats given different combinations
of high or low protein diet, high or low calcium diet, as well as
cadmium in the diet was performed by Abe, Tanaka and Itokawa, 1972.
The rats were studied for only four weeks and the cadmium given
was about 200 ug/g in the food corresponding to a daily intake
of 1.5 mg. After four weeks the average cadmium level in the kid-
ney was about 200 ug/g dry weight and in liver about 150 yg/g dry
weight. The bones were examined roentgenologically and the group
given low protein and low calcium together with cadmium exposure
showed an abnormal curvature of the spinal column. It is difficult
to evaluate the actual pathophysiological changes in the bones.
Nomiyama, 1974, gave rabbits 300 ug Cd/g in food corresponding
to a daily dose of about 36 mg Cd (sections 4.2.2 and 4.2.3.1).
The earliest effects were an intermittently increased excretion
of amino acids in urine after 16 weeks of feeding. At around
-------
5-7
the same time an intermittently increased excretion of enzymes
such as alkaline phosphatase, GOT and GPT was recorded. Alka-
line phosphatase in urine was significantly increased 3 times
out of 16 between 14 and 52 weeks of exposure as seen in Nomiyama
et al., in press (see section 4.2.3.1). GOT and GPT were
only significantly increased during weeks 14 to 28 of exposure
and not thereafter. Nomiyama, 1974, stated that hemoglobin was
reduced after 27 weeks and that total protein and sugar excreted
in urine reached elevated levels after 38 and 42 weeks respect-
ively (see section 4.2.3.1). The cadmium concentration in kid-
ney cortex at the time at which intermittent aminoaciduria dev-
eloped was 200 ug/g wet weight whereas the total proteinuria
and glucosuria developed at the concentration of about 300
ug/g. Nomiyama, 1974, claimed that no increased excretion
of cadmium in the urine as a symptom of the kidney damage
could be ascertained. It is doubtful whether such a conclu-
sion can be reached in view of the obvious risk of contamination
since the daily oral dose was 36 mg and the daily excretion
30 ug in urine and slightly less than 36 mg in feces (section
4.2.3.1).
In rats exposed subcutaneously to 0.5 ug Cd/kg body weight six
days per week for 16 weeks, urinary protein excretion increased
and urinary cadmium excretion increased dramatically (see
Figures 4:10 and 4:11, section 4.2.2) at a calculated kidney
cortex level of about 225 ug Cd/g wet weight (1.5 x 150)
(Suzuki, 1974). These data confirm earlier data discussed
in CITE, 2nd ed., regarding the relation of urinary cadmium
to kidney damage.
Murase et al., 1974, studied the microscopic pathology of liv-
er, kidney and some other organs in dogs that had received 500
ml of drinking water containing 100 ug Cd/g daily for 13 months.
Cadmium in the cells was specifically stained with the Okamoto
method. Two exposed dogs were compared with one control. There
were hemosiderin deposits in the Kupffer cells and the liver
blood vessels. An increased number of lymphocytes were discovered
in the vascular regions of the liver as well as in the kidney,
-------
5-8
but in the kidney no changes were seen in the vessels themselves.
There were pathological changes in about 30% of the glomeruli
and about 25% of the proximal tubular epithelium.
No cadmium staining could be seen in the liver cells, but in
the mesangium cells of the renal glomeruli as well as in the
proximal tubular epithelium cells, fine cadmium stained
granules were seen. These were diffusely spread throughout
the cortex and in the same places, pathological changes in
the cells were evident.
In CITE, 2nd ed., aminoaciduria was reported to be a common
finding among cadmium-exposed workers and Itai-itai disease
patients. As presented above, Nomiyama, 1974, found inter-
mittent aminoaciduria to be the earliest indication of renal
tubular damage by cadmium. Foulkes and Gieske, 1973, studied
the specificity of metal effects on renal amino acid transport
in a peracute study (20-60 seconds). The venous blood flow from
rabbit kidneys was diverted into a vessel where samples could
be taken at short intervals (seconds). By infusing labelled amino
acids together with metal compounds as well as inulin, the in-
hibition of renal reabsorption of filtered amino acids could
be measured. The authors reported that glutamate and aspartate
reabsorption in the rabbits was specifically inhibited (24-
68% inhibition) by an intraarterial cadmium dose of 2.5 umoles
Cd/kg body weight (0.28 mg/kg) given together with mercapto-
ethanol. Arginine reabsorption was inhibited 13-37% while the
inhibition of phenylalanine, alanine, serine and lysine was
lower or zero.
In conclusion it can be said that the recent studies on animals
support the findings reported in CITE, 2nd ed. There are indica-
tions that histological changes in bones may develop earlier than
renal damage but the data are not yet conclusive. It can still be
said that the proximal renal tubules are the critical organs in
chronic cadmium poisoning. Experimentally induced osteomalacia has
been reported in cadmium exposed rats.
-------
5-9
5.1.2 Studies on highly exposed groups
Metabolic aspects of the bone changes in chronic cadmium
poisoning have been studied by Sano and Iguchi, 1974.
They discussed the possibility that a decline in the
formation of protocollagen or a disturbance of the
hydroxylation of protocollagen would cause on the one
hand an increased urinary excretion of proline and
on the other hand an impairment of polymerization of
soluble collagen. This would cause an accelerated
decomposition of this type of collagen and increased
excretion of hydroxyproline in urine (see Figure 5:1).
Sano and Iguchi analyzed the excretion of free and
bound proline and hydroxyproline in urine from 7 Itai-
itai patients in the Fuchu area of Japan, 7 cadmium
exposed persons in the Ikuno area, 5 cadmium workers and
10 control persons. Neither the exposure time nor
the age of the persons were stated by the authors.
As is seen in Table 5:2, a consistent increase in
the excretion of these imino acids occurred among
the Itai-itai patients from the Fuchu area. Most of
the cadmium exposed persons in the Ikuno area, as
well as the cadmium exposed workers, displayed a higher
total imino acid excretion than the controls. The
largest increases are in the excretion of free imino
acids which in the first place might be a symptom
of the decreased tubular reabsorption of these compounds,
but the excretion of bound imino acid is also signi-
ficantly elevated, especially in the Itai-itai patients,
indicating the possibility of some abnormality in
collagen metabolism.
Horstowa, Sikorski and Tyborski, 1966, presented the
results of examinations carried out among 26 workers
in Poland exposed to cadmium in the manufacture of
alkaline batteries. Exposure time varied between 1-12
-------
5-10
years and the exposure to cadmium in air was calculated
as 0.13-1.17 mg/m3. It is not mentioned in detail how
the 26 workers were selected/ but all had some form of signs
which, according to the authors, could indicate chronic cadmium
poisoning.
Proteinuria was detected in 7 out of the 26 workers, in 6 of
these cases remaining after cessation of exposure. According to
the authors, this indicated that the changes in the kidneys were
persistent. The erythrocyte sedimentation rate was on an average
14 mm per one hour. Reduced vital capacity was found in 12 of
the workers and emphysema in 17 upon X-ray. X-ray of the skeleton
showed signs of osteoporosis in 10 cases. The occurrence of several
other unspecific symptoms and signs is discussed. Difficulties
exist in interpreting the paper, among other things due to the
absence of controls and the nature of the methodology, which
cannot be well understood without a knowledge of the basic Russian
reference literature.
Lauwerys et al., 1974, reported on epidemiological studies of
workers in Belgium exposed to cadmium in three different factories:
an electronic workshop, a nickel/cadmium storage battery factory,
and a cadmium-producing plant. In each factory a control group
was selected to match the exposed group according to sex, age, •
weight, height, smoking habits and socio-economic status.
Total dust as well as respirable dust (aerodynamic diameter <.
5 urn) was measured 'in the breathing zones of the workers. Each
measurement covered about 4 hours and was repeated 4-5 times.
The authors measured the cadmium concentration in the air only
in connection with their present study, but were of the opinion
that the said levels in the three plants were quite representative
of past exposure, no important modifications having occurred
in the different industrial processes since their installation.
As always when no actual data exist on past exposure such
a statement is open to discussion.
-------
5-11
One group of 31 women (mean age: 30.5 years) was exposed for a
mean period of 4 years (range: 1-12 years) to an average total
and respirable (aerodynamic diameter < 5y) airborne cadmium dust
3 3
concentration of 31 yg/m and 1.4 yg/m , respectively (this group
is in the article and here referred to as group E 1). The only dif-
ference upon comparison with the controls was a slight increase in
the urinary cadmium concentration (5.3 yg/g creatinine for the
workers and 2.0 yg/g creatinine for the controls). Blood values
were 2.0 yg/100 ml and 1.0 yg/100 ml for workers and controls
respectively.
Group E 2 consisted of 27 men (mean age: 38.6 years) exposed to
an average total cadmium dust concentration of 134 yg/m for
0.6-19.6 years (mean: 8.6 years). The average respirable cadmium
dust concentration at the most polluted worksite was 88 yg/m .
All pulmonary indices were on the average lower for the exposed
than for the controls. None of the differences was significant,
however. Average blood concentration of cadmium (3.0 yg/100 ml)
among exposed workers was significantly higher than that of the
controls (p <0.05). In 4 out of the 27 workers electrophoresis of
urinary proteins showed a pattern of glomerular proteinuria. Only
one of the controls, known to suffer from glomerulonephritis, had
proteinuria.
The methods used for electrophoresis of urinary proteins differed
from methods employed in other studies. The urine proteins were
concentrated to a volume corresponding to a creatinine concentra-
tion of 100 mg/ml, i.e. if the original creatinine concentration
in urine was 100 mg/100 ml, the urine was concentrated 100 times.
This means that if the original protein concentration was 10 mg/100
ml, the protein concentration in the concentrate would be only
10 mg/ml, which gives a very weak pattern in the agarose electro-
phoresis used in this study. Thus early tubular patterns may not
have been recognized.
-------
5-12
It is obvious that a positive finding by these authors mainly
reflects a high protein excretion since at higher protein ex-
cretions in the original urine the concentrate will have a
higher concentration. This is also borne out by the fact that
electrophoretic patterns of urine proteins were not visible
in the urine from two persons with 134 and 337 mg/g creatinine
respectively, whereas from two persons with 851 and 1,254
mg protein per gram creatinine/ clearly visible patterns were
obtained (Figure 5:2).
Group E 3 consisted of 22 men (mean age: 51.5 years) exposed for
21-40 years (mean age:27.8 years) to an average total and
respirable cadmium concentration of 66 ug/m and 21 Ug/m
respectively. There was on an average increased cadmium con-
centration in urine and in blood. There were also changes
in certain enzyme activities in blood and practically all
pulmonary function tests carried out showed on an average
pathologic values. Abnormal urinary protein, patterns were
revealed upon electrophoresis in 15 of the 22 urine samples
from workers compared with none in the urine of the controls.
The data are given in detail in Tables 5:3, 5:4, and 5:5.
The excretion of cadmium in urine was also clearly related
to the occurrence of proteinuria, as seen in Table 5:6.
In their discussion the authors concluded that the present TLV
value is too high and recommended reduction of the TLV for cad-
mium dust to 50 ug/m . The groups studied by Lauwerys et al.,
1974, would be very interesting to restudy in the future due to
the careful collection of background data both among exposed
and controls.
Tsuji et al., 1972, reported a study of 1,420 workers in the
zinc refining plant of Annaka in Japan. Examinations for protein-
uria, glucosuria and subjective symptoms were made on 1,398 per-
sons. The group consisted of 1,247 men and 148 women who were
divided into a low cadmium exposure group (619 persons) and
a high cadmium exposure group (681 persons). A special study
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5-13
was also performed on 92 workers who were directly engaged
in the production of cadmium. No control group was studied.
Total average prevalence of proteinuria was about 15% when
using the sulfosalicylic acid method and 6 1/2% and 9 1/2%
in men and women respectively when using the trichloracetic
acid method. Glucosuria (test-tape) was reported in 7.8% of
the men and 1.4% of the women, in the group of workers dir-
ectly engaged in cadmium production, the average prevalence
of proteinuria (sulfosalicylic acid method) was 27 1/2% and
25% for men and women respectively. Among men over 50 years
of age the prevalence was 50%.
The workers were examined for the yellow dental cadmium ring,
but none of them had it. The workers engaged in cadmium pro-
duction had significantly more respiratory tract and nasal
symptoms than the other workers.
Tsuji et al., 1972, did not report on the cadmium exposure in
the factory nor did they divide the workers into exposure time
groups.
Nogawa et al., 1972, studied 283 painters of ceramics who were
exposed to lead and cadmium. No control groups were studied.
The urinary excretion of lead averaged about 70 ug/1 in men
and 50 ug/1 in women whereas the cadmium excretion in men
and women averaged about 6 ug/1. Cadmium excretion in urine
showed a tendency to increase with age, but lead excretion
showed no such tendency.
Proteinuria, glucosuria, hematocrit and hemoglobin were measured
as effect indicators but no statistically significant differences
between groups with different urinary cadmium excretion could
be seen. On the other hand, when persons without proteinuria
or glucosuria were compared with those with proteinuria or glu-
cosuria, the cadmium excretion (expressed as ug/1 urine) was
significantly higher in the latter group in all age categories
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5-14
(up to 29 years, 30-59 years and 60 years or more). However,
when cadmium excretion was expressed as ug/g creatinine, no
statistically significant differences were seen.
Harada, 1973, and Harada.et al., 1974, reported on a study of 19
workers in a cadmium pigment plant. No control group was studied
but as seen in Table 5:7 a form of dose-response relationship be-
tween exposure time and proteinuria came forth. Proteinuria as mea-
sured by the trichloracetic acid method as well as by patho-
logical patterns on disc electrophoresis hardly occurs at less
than 5 years of exposure whereupon the prevalence increases.
The air concentrations of cadmium were measured once in each
part of the factory, the averages ranging from 24 ug/m to
more than 7 mg/m (Harada, 1973). The author calculated that
the worker with the longest exposure time and the most severe
symptoms had been exposed to an average concentration of cadmium
in workroom air of about 114 ug/m . The average concentration
where most of the workers were stationed was estimated at
50 ug/m (Harada, personal communication) . The average urine
cadmium excretion (ug/g creatinine, measured twice) ranged
between 3.8 and 34.8 in those workers who did not have an
increased globulin fraction on disc electrophoresis and from
23.4 to 130 ug/g creatinine in those who had a clear patho-
logical increase of the globulin fraction on disc electropho-
resis .
5.1.3 Studies on populations in Japanese cadmium-exposed areas
In CITE, 2nd ed., it was concluded that, in Fuchu area of
Toyama Prefecture, the widespread occurrence of tubular pro-
teinuria and the endemic of osteomalacia or severe osteoporosis
in connection with such proteinuria were correlated to the
level of cadmium exposure. Cadmium was seen as one of the
etiological agents for these symptoms. In some of the other
cadmium-exposed areas of Japan, proteinuria had also been
regarded as an expression of cadmium poisoning of the general
population. Some additional data from the areas mentioned
in CITE, 2nd ed., will be dealt with here.
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5-15
Shiroishi et al., 1972, studied 242 persons in S-village in
Fuchu area of Toyama Prefecture as well as 161 persons in
0-village (control area). It was not stated exactly how the
target population was selected, but it consisted of 123 men
and 119 women over 40 years of age in the S-village and 75
men and 86 women in the other village. Urine was studied for
proteinuria with the Kingsbury-Clark method as well as with
disc electrophoresis and for glucosuria with test-tape
and the OTB-method. The occurrence of different patterns
on disc electrophoresis is shown in Figure 5:3. The prev-
alence of Itai-itai disease pattern increases from about
10% in the 40-50 year age group to about 50% in the 70-
80 year age group in this study.
In another study of 110 persons from the Fuchu area (Fukuyama
et al., 1972) 24-hour urine samples were collected. Cadmium
concentration was analyzed with atomic absorption after
dithizone/chloroform extraction. Disc electrophoresis was
also performed.In Figure 5:4 comparison is made between
living time in the area and excretion of cadmium in the
urine in the polluted area versus a control area. At around
40 years' time of residence, the cadmium excretion reaches
its maximum, the prevalence of Itai-itai patterns on disc
electrophoresis increasing drastically. After 45 years of
residence in the area almost all persons in this study
showed Itai-itai disease patterns and" the average urinary
cadmium excretion exhibited an age-related decrease.
Fukushima et al., 1973, reported on the cadmium concentrations
in glutinous and non-glutinous rice as well as prevalences of
proteinuria and glucosuria from villages within the Fuchu area.
Non-glutinous rice is the type consumed as a regular food. The
data from 37 villages are summarized in Figure 5:5. Response was
measured as concurrent proteinuria (sulfosalicylic method) and
glucosuria (Test-tape). As seen in the figure, response rate
increases with increasing cadmium concentration in rice. The
correlation coefficient for all 37 villages between response
-------
5-16
rate and rice-cadmium (non-glutinous) is 0.62, which is statis-
tically significant.
I
The type of proteinuria among the Itai-itai patients and other
cadmium exposed persons in the Fuchu area has been given con-
siderable attention as accounted for in CITE, 2nd ed. Low mol-
ecular weight proteins like S.-microglobulin and retinol-binding
protein (RBP) have earlier been shown to be elevated in the
urine among Itai-itai patients. This finding has now been
given further support by Ohsawa and Kimura, 1973, as well as
by Kanai et al., 1971. Kanai et al. also demonstrated that the
increased excretion of RBP occurred among the relatives of
Itai-itai disease patients. There was a distinct difference
in the ratio between albumin and RBP among persons with Itai-
itai disease as compared to persons with other renal diseases
(Figure 5:6). Kanai et al., 1971, measured RBP with the
single immunodiffusion method (Mancini). In later work they
employed radioimmunoassay (Kanai et al., 1972), showing that
the RBP level in serum of Itai-itai disease patients was not
different from that of control persons. The increased excre-
tion of RBP was concluded to be a symptom of decreased tubular
reabsorption.
Utilizing isoelectric focusing, Vesterberg and Nise, 1973,
showed a 4-60 times higher excretion of 32-microglobulin in
urine of 43 persons from the Itai-itai disease area than in the
urine of 100 normal Swedes. Shiroishi et al., to be published,
compared 10 Itai-itai disease patients, 32 observation patients
(kidney symptoms but no bone symptoms, living in the Fuchu area)
!)
and 17 Japanese control persons. The increase in urinary $9-micro-
globulin (radioimmunoassay) was about 200-fold whereas the increase
of total proteins was only about 15-fold when the observation
patients and the control persons were compared. There was no
significant difference between Itai-itai patients and observa-
tion .patients (See Table 5:8).
Nomiyama et al., 1973, studied the nature of urinary proteins
in 7 female patients with Itai-itai disease. They found the
-------
5-17
molecular weights to be from 12 to 45 x 10 , agreeing well with
previous reports dealing with renal tubular dysfunction. Some
of the low molecular weight proteins were' retinol binding
proteins and 32-microglobulin proteins. There was some indi-
cation that the retinol binding protein was made up of the
holo type to a greater extent than the apo type (holo
type = RBP bound to vitamin A and apo type = free RBP) in
Itai-itai disease patients as compared to cadmium workers
with proteinuria. The authors speculated that the reason
might be that Itai-itai disease patients have been treated
with very large doses of vitamin A. There are very little
actual data supporting a systematic difference between Itai-
itai patients and cadmium poisoned workers in the paper.
From Ikuno area of Hyogo Prefecture some additional data are
now available. Watanabe and Murayama, 1974, found no difference
in the study of April, 1971, as to the average prevalence of
proteinuria (trichloracetic acid method) between groups of
villages with an average cadmium concentration in unpolished
rice ranging from 0.33 ug/g up to 1.10 ug/g. In this same
report, another study on 39 persons from a highly polluted
area and 56 persons from a non-polluted area, in both cases
randomly selected persons over 70 years of age, is discussed.
In this study the prevalence of protein concentration above 10
mg/dl (as measured with a Biuret method) was 53.9% in the cadmium
exposed group and 41.1% in the control group. In the same groups
the prevalence of g_-microglobulin concentration in urine above
10 ug/ml (Mancini method) was 41% in the exposed group and 3.6%
in the control group. Lysozyme concentration in urine above 1
wg/ml occurred in 20.5% of the exposed persons and 3.6% of the
control persons.
In conclusion it can be said that the newly available data from
Japan further strengthen the conclusions reached in CITE, 2nd
ed. The obvious possibilities of making large scale dose-response
studies on early effects of cadmium in the general population
have still not been realized.
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5-18
5.1.4 Etiology of Itai-itai disease
Whether or not cadmium was one of the etiological factors for
Itai-itai disease is still under intense discussion in Japan.
Kajikawa et al., 1974, reported clinical and pathological
findings in 11 cases of Itai-itai disease. The patients were
autopsied between 1955 and 1961 and the results are summarized
in Table 5:9. One patient had severe osteoporosis, two patients
had primary hyperparathyroidism, and the other eight patients
had osteomalacia at various stages of recovery. Kajikawa et
al. concluded that the bone injury in Itai-itai disease is
synonymous with osteomalacia. There is a difference between
the two patients autopsied in 1955 and the six autopsied after
1965. The bone disease in the earlier patients was much more
severe while in the later patients it was at different stages
of recovery. In the kidneys of the two earlier patients chronic
pyelonephritis and arteriosclerosis were found whereas tubular
atrophy accompanied by interstitial fibrosis was found in the
later patients. Kajikawa et al. reported that according to clin-
ical examinations the later patients had a more severe damage
of the kidney function and four of the six later patients
died of uremia. The methods for analyzing proteinuria were
not stated and no further clinical data were reported re-
garding the two earlier patients.
The advanced pathological changes in the kidneys must be
hard to differentiate from the kidney findings in the
other patients, hindering such a conclusion that the
kidney damage was more severe in the later patients. Kajikawa
et al. , 1974, also studied autopsy findings in 155 patients
who died from diseases other than Itai-itai disease. None
of them had any known cadmium exposure. Of these patients 10
in the age range 26-79 years had tubular changes similar to
those in Itai-itai disease. According to Kajikawa et al., the
qualitative rating of "tubulopathy" in the Itai-itai disease
patients was + to +++ and among the 10 other patients five had
-, three had + and two had ++. Seven of the 10 patients had
died from cancer. These findings indicate that tubulopathy as
diagnosed by Kajikawa et al. was an uncommon finding among
-------
5-19
Japanese people dying from various diseases as compared to those
dying with Itai-itai disease. On the other hand, 10 tubulo-
pathies among 155 persons is not a low prevalence in itself.
Kajikawa et al. concluded that it cannot be denied that the
kidney findings among Itai-itai disease patients could be
caused by chronic cadmium poisoning. On the other hand, they
say that this kind of tubular damage has also been found among
other patients in whom no increased cadmium exposure could be
traced.
Apart from one of the Itai-itai patients, Kajikawa et al.,
1974, could not find pathological signs in the kidney typical
for vitamin D poisoning. Thus Kajikawa et al. maintained that
it is very hard to conclude that the kidney damage in Itai-
itai disease could be caused by vitamin D poisoning as had
been suggested by Takeuchi, 1973. According to Kajikawa et
al.,the kidney changes in the patients deteriorated over
time whereas the bone changes improved. Vitamin D was effect-
ive in the treatment of the bone disease. Based on the observa-
tions they suggested that the .bone findings in Itai-itai dis-
ease can hardly be caused by a cadmium-induced secondary vitamin
D deficiency with osteomalacia. Instead, these authors believe
the bone findings to be caused by malnutrition and vitamin D
deficiency.
Kajikawa et al., 1974, also reported the cadmium concentration
in various organs from seven of the Itai-itai patients and
from one person who had lived in the polluted area and from
whom they took biopsies during an appendectomy. The data from
five of the patients are the same as reported by Ishizaki,
Fukushima and Sakamoto, 1970. The cadmium concentration
in the liver of the other two patients was 56.5 and 65.8
yg/g/ similar to the values for the five patients earlier
published by Ishizaki and associates. The person with appen-
dectomy had a liver concentration of 41.8 ug/g. The concen-
tration of cadmium in the kidney cortex was 17.9 pg/g in
patient number 5 who had highly severe morphological kidney
-------
5-20
damage (see Table 5:9). Patient 11 had a renal cortex cadmium
concentration of 123 ug/g. As seen in Table 5:9, this patient
did not have any tubular nephropathy but only arteriosclerosis
of the kidney. Patients 6,7,9 and 10 had similarly low renal
cortex cadmium concentrations as patient 5 and as seen in
Table 5:9 morphological changes were also more severe
in the tubules than those of patient 11. These data support
the theory that low cadmium concentrations in kidney of Itai-
itai disease patients and workers with chronic cadmium poi-
soning were due to severe kidney damage.
Hagino, 1974, also discussed the etiology of Itai-itai disease
but no new actual data were reported.
Hagino et al., 1970, reported the average urinary cadmium con-
centration in 9 patients of which 3 died. Twenty-four-hour
samples were taken for about twenty days during two months.
The average cadmium concentrations for the patients that
were still alive were 12.9, 6.8, 24.5, 32.9, 7.3 and 16.1
ug/1. Among the three patients who died, the concentrations
were 5.8, 7.7, and 9.9. In 1974, four years after the study, a
fourth patient had died, i.e. the one having 6.8 at the
sampling reported upon in 1970 (Hagino, personal communication).
Hagino, 1974, concluded that patients with a severe case of
Itai-itai disease and near death usually have lower cadmium
concentrations in urine than other patients. According to
him, this shows that cadmium concentration in urine cannot
serve as an indicator of the exposure.
Recently much discussion in Japan has centered around the pos-
sibility that Itai-itai disease has occurred in areas other than
the Fuchu area. As was mentioned in CITE, 2nd ed, ,
authors have claimed that they have found at least 5 patients
in the Ikuno area. More clinical data are now available;
Nogawa et al., 1973, showed that one of the said patients had
a syndrome very similar to Itai-itai disease, including tubular
kidney dysfunction, increased alkaline phosphatase in serum,
-------
5-21
decalcified bones and multiple fractures. Some of these fractures
were similar to the pseudofractures of osteomalacia. According {
ij
to Nogawa et al., the average cadmium content in the rice har- •
vested on the patient's farm was 0.64 y.g cadmium per gram dry
weight. This may correspond to a concentration of about 0.55
,yg Cd/g wet weight.
Additional data about this and two other patients are given
by Ishizaki et al., 1974. One of these patients had died and
the cadmium content was analyzed in samples of tissues received
at autopsy,. The cadmium concentration in liver was 75 ug/g
wet weight and the zinc concentration 116 ug/g wet weight. In
kidney cortex the cadmium concentration was 53 ug/g wet weight
and the zinc concentration 48 ug/g wet weight. Another organ
with very high cadmium concentrations was the pancreas where
52 \*g/g wet weight of cadmium and 56 ug/g wet weight of zinc
were found. The cadmium content in liver, much higher than
what is commonly found in Japan, was in the same range as for
the Itai-itai disease patients in the Fuchu area. The cadmium
concentration in kidney cortex was low in comparison with the
liver value, probably due to the increased excretion of cadmium1
after kidney damage developed. Similarly low concentrations were
also found among the Itai-itai patients in Fuchu area.
The scarcity of the data on individual Itai-itai disease
patients, the lack of systematic follow-up studies on the
patients, as well as dearth of autopsy data render the
picture incomplete. Nothing that has come forth in the new
data would influence the conclusions arrived at in CITE
2nd ed., that the Itai-itai disease is one form of chronic
cadmium poisoning. The new data accumulating from the Fuchu
and Ikuno areas on the contrary support the earlier conclusion.
Because of the small number of suspected cases found in Ikuno
area it is not possible to say whether the syndrome is actually
etiologically limited to cadmium exposure. The recent autopsy
data, however, show that inhabitants of the area may be equally
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5-22
as exposed as those in the Fuchu area. Further research is needed
into the prevalence of osteomalacia in the cadmium-exposed
and control areas.
5.2 EFFECTS ON CALCIUM AND VITAMIN D METABOLISM
In CITE, 2nd ed., studies were reported that indicated an in-
terrelationship between cadmium- and calcium- metabolism. Ob-
servations taken up there were that calcium-deficient rats have
a higher cadmium uptake; a high prevalence of renal stones among
cadmium workers suggested a disturbed metabolism of calcium
and phosphorus. In addition, the effects of cadmium on bone
were also reported as being secondary to effects on calcium-
phosphorus metabolism. An impairment of the renal tubular regula-
tion of Ca/P balance was proposed in CITE, 2nd ed., as the
most important factor for elicitation of bone changes in v/orkers.
The mechanism behind the Itai-itai disease has been arduously
debated during recent years. Just as was the case for cadmium
workers, cadmium was mainly linked to the osteomalacia by the
epidemiological findings.
Sugawara and Sugawara, 1974, studied the influence that cadmium
would have on calcium uptake from the intestine of rats. Three
groups of 5-13 rats were given a diet ad libitum containing
0.22% calcium. In one group the food was mixed with a solution
of cadmium in drinking water at the cadmium concentration of 10
pig/g and in another group cadmium concentration in drinking
water was 50 ug/g. The rats were studied for 287 days and during
days 3-24, days 45-66, days 161-182, and days 259-280, the
total amounts of feces and urine were collected. During this
time, the total food and water consumption was also measured.
Calcium and phosphorus were analyzed in feces and in urine
with atomic absorption method and the Allen method, respect-
ively. Calcium and phosphorus absorption rates were calculated
from the balance.
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5-23
No significant differences in calcium or phosphorus absorp-
tion rates were seen between the control group and the group
given 10 ug Cd/g in drinking water . There was a significant
decrease in the calcium absorption rate to about half
for the group given 50 ug Cd/g in drinking water and a
decrease of about 25% in phosphorus absorption in the
same group.
i
Sugawara and Sugawara, 1974, reported that in hematoxylin- J
eosin stained sections of the duodenum, pathological findings
such as eosinophilic cell infiltration and erosions could
be spotted in some of the rats given 50 yg Cd/g in drinking
water. These authors suggested that the intestinal damage
caused by cadmium leads to disorders of calcium metabolism.
However, the only disorder shown in their study is the !
decreased uptake.
Studies into the effects of cadmium on calcium metabolism
have also been reported by Kobayashi, 1973. Cadmium was
mixed into a calcium-deficient diet in the amount of 30-
100 ug/g. Rats given this diet then showed a negative
calcium balance compared with rats on a calcium deficient
diet without added cadmium. Figure 5:7 illustrates the
calcium balance for individual rats, the positive numbers
meaning that more calcium is gained from the diet than
is excreted, and negative ones meaning that more calcium
is excreted than was present in the diet. Kobayashi also
noted that practically all the calcium excretion was via :
the feces. He therefore stated that a hypothesis that bone
changes are caused by renal dysfunction was not supported.
Instead, the postulation is favored that the loss of calcium
is due to lower absorption of calcium and to a high excretion
via the intestines.
I
The studies described above involved an exposure to cadmium
via drinking water. The mechanism behind the effects on
calcium uptake is therefore hard to evaluate.
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5-24
The role of vitamin D in calcium metabolism has recently
been reviewed by Kodicek, 1972. The active metabolite
af vitamin D, 1,25-dihydroxycholecaliferol (1,25-DHCC),
is formed in the kidney and stimulates calcium absorption
from the intestine. A feedback control system including
the calcium concentration in serum and parathyroid hormone
(PTH) is involved in vitamin D metabolism. A schematic
drawing of these pathways is shown in Figure 5:8. New
data regarding the metabolism of vitamin D indicate that
cadmium may have an inhibitory action on the enzymes necessary
for the activation of vitamin D into 25-HCC and 1,25-DHCC.
In an experiment by Unger and Clausen, 1973, cadmium was ad-
ministered by interperitoneal injection to groups of 2-
10 mice. The dose varied between 0.1 ng Cd (as cadmium
nitrate)/kg body weight up to 50 mg/kg body weight. The
specific P-450 0-demethylation activity in liver microsomes
was measured four days after the injection of cadmium.
Table 5:10 reveals a type of dose-response relationship
between decrease in P-450 activity and cadmium dose. The
authors concluded that cadmium in vivo can affect metabolic
transformations where the enzyme P-450 is involved, one of
which is the transformation of vitamin D to 25-HCC.
Feldman and Cousins, 1973, studied the influence of cadmium
on the synthesis of 1,25-DHCC in vitro in kidney mitochondria
from chicks. The isolated chick kidney mitochondria were
incubated together with solutions containing varying concen-
trations of cadmium chloride. Tritium-labelled 25-HCC was
added and the metabolites formed after further incubation
were separated by chromatography on a Sephadex column.
The tritium content of each chromatographic fraction was
measured with a liquid scintillation spectrometer. In
this way it could be shown that increasing concentrations
of cadmium depressed the formation of 1,25-DHCC (See Table
5:11). A similar experiment with other bivalent cations
(Pb,Hg, Zn, Cu and S) with the same molarity showed that
cadmium and lead depressed the formation of 1,25-DHCC
in the most effective way.
-------
5-25
Feldman and Cousins, 1973, also showed that chick cadmium-
binding protein eliminated a large part of the inhibitory
influence of cadmium on the chick kidney mitochondria formation
of 1,25-DHCC. These effects of cadmium in vitro on vitamin D acti-
vation in the kidney have been confirmed by Suda et al. , 1974.
Feldman and Cousins, 1973, studied the effects of cadmium
in vivo on the renal vitamin D metabolism. 50 yg Cd/g in drinking
water had been administered for two weeks to chicks given
a low calcium diet. During eleven days they received intraperi-
toneal injections of Img Cd/day as cadmium chloride. After
this time the chicks were killed and the hydroxylation activity
in the isolated chick kidney mitochondria was tested. In the
control chicks 50% of the substrate had been converted into
1,25-DHCC and in the cadmium-treated chicks only 30%. The ex-
treme exposure resulted in a very high concentration of cadmium
in the mitochondria, 770 ug/g of mitochondrial protein.
A similar experiment on the hydroxylation of 1,25-DHCC in the
kidney was related by Kimura et al., 1974. Cadmium was
fed with the diet in different concentrations to mice and
the feeding time was slightly longer than in the experiment
by Feldman and Cousins, 1973 (see Table 5:12). The production
of 1,25-DHCC was slightly depressed in the groups given the
highest doses. The difference in relation to controls was not
statistically significant. (The number of animals was 2-3 in
each group). In the group given the highest cadmium dose the
concentration in total kidney was 36.5 ug/g wet weight. It may
be that the cadmium concentration in kidney cortex was not high
enough to induce large changes in the enzyme activity.
Cadmium-induced osteomalacia among rats has been reported by
Itokawa et al., 1974 (section 5.1.1.2).
In conclusion the data reported above indicate that cadmium both
in vitro and in vivo may inhibit enzyme activities which are
important for the formation of the active metabolite of vitamin
D in the kidney tubular cells. The data are still insufficient
to explain the role of cadmium in bone mineral metabolism and
further studies are needed.
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5-26
5.3 EFFECTS ON THE CARDIOVASCULAR SYSTEM
It has earlier been claimed that hypertensive patients excrete
more cadmium than normotenslves (CITE, 2nd ed.). Wester, 1973,
studied urinary excretion of cadmium in 16 hypertensive patients
(11 men and 5 women, age 28-60 years) before and during treatment
with chlortalidone (an anti-hypertensive and diuretic agent).
Cadmium was determined with neutron activation. The mean daily
excretion during 5 days before treatment was 2.1 yg and during
5 days' treatment 2.9 yg. This increase was statistically
significant. The daily excretion in the hypertensives did not
differ from that in normotensives. Cadmium was also determined
in plasma. In 8 normotensive subjects a mean concentration of 2.5
ng/ml was found compared to 2.0 and 2.6 ng/ml in the hypertensive
subjects before and during treatment. These results indicate that
hypertensives do not differ from normotensives with regard to
urinary excretion of cadmium. That chlortalidone caused an in-
crease is explained by its chelating action. It can be mentioned
that in the same study the excretion of zinc increased conside-
rably during treatment.
Voors, Shuman and Gallagher, 1972, analyzed cadmium and zinc in
different organs from about 100 autopsies from two areas in North
Carolina, a rural area with high death rates in cardiovascular
diseases, and an industrialized area with only moderate cardio-
vascular mortality. Information on smoking habits was obtained
for about 64 % of the deceased persons by means of question-
naires filled in by their relatives.
Cigarette smoking was positively associated with kidney cadmium
levels. Cadmium concentrations in the organs analyzed were also
slightly higher in atherosclerotic than in non-atherosclerotic
patients, although the differences were not statistically signif-
icant. The cadmium to zinc ratio in the kidneys was slightly
higher in the atherosclerotic than in the non-atherosclerotic
subjects (ratio: 0.68 and 0.55 respectively). The difference
was statistically significant. The authors were cautious in
-------
5-27
interpreting their findings; the results may be a manifestation
of the hypertensive process but increased cadmium levels could
merely indicate increased exposure to environmental agents such
as cigarettes, which were not possible to control for completely
in the analyses.
Thind, Biery and Bovee, 1973, reported on the induction of arte-
rial hypertension in 7 dogs after intraperitoneal injections of
cadmium acetate (2 mg/kg body weight, about 25 injections during
36 weeks). Systolic blood pressure showed an increase of between
10 to 20 % on an average. There was no tendency to further in-
crease in pressure after the sixth week. The authors did not use
a control group, nor did they report any individual data. These
gaps, plus the rather slight increase without dose relationships,
make it impossible to evaluate the study.
Apart from the long-term study by Thind, Biery and Bovee there
are studies in which different parameters, which might have a
bearing on vascular effects, have been examined after single
injection of cadmium compounds. In the brown bat, Youkilis et al.,
1971, disclosed that a single intraperitoneal injection of
3 mg Cd/kg gave rise to small arterial dilatation while injec-
tion of 1 mg/kg cadmium caused small arterial constriction.
Perry and Erlanger, 1973, found increased renin activity after
injection of cadmium and mercury respectively. Thind, 1973, stated
that cadmium and isoproterenol produce vascular relaxation (as studied
on rabbit aorta strips). Massive doses of cadmium sulfate (2 mg/kg
body weight intraperitoneally daily until 15 to 22 doses had
been administered) were given to chickens by Sturkie, 1973.
Compared with controls there was no increase in blood pressure,
but a pronounced anemia was said to have arisen in the exposed
animals. Toda, 1973, investigated the acute effects of cadmium
ions on isolated hearts from rabbits and found several indica-
tions of an inhibitory action of the electrical activity of
sinoatrial node pacemaker fibers.
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5-28
During recent years a number of reviews on the relation between
i
minerals and cardiovascular disease, particularly hypertension,
have been published (Masironi et al., 1972, Masironi, 1973,
Perry, 1973). As regards cadmium, the focus has been on the
hardness of drinking water. Though some of the investigations
have found an association between the two factors, it has been
consistently stated that no proof of causality in human beings
has yet come forth.
Perry, 1973, named three possible mechanisms by which cadmium
might raise blood pressure. In acute hypertension induced' by
parenteral cadmium, the immediate increase in pressure is
directly related to an increase in cardiac out-put. When chronic
hypertension has been experimentally induced by cadmium, a corre-
sponding increase in the circulating renin has appeared. The
third mechanism may be related to the finding that repeated
cadmium exposure induces a long term antinatriuretic effect.
5.4 EFFECTS ON THE TESTICLES
A vast literature has come to the fore concerning the acute effects
of cadmium injection on the testicles and non-ovulating ovaries of
various mammalian species, as has been pointed out in CITE, 2nd ed.
Variation in susceptibility has been shown among species and even among
strains of the same species. The reason for such variation has
not been elucidated, nor has the exact biochemical, pathogenetic
mechanism for the acute effect of cadmium on testicles, though
several theories have been propounded. These two matters have
been dealt with in many reports published during the last two
years.
Sangalang and O'Halloran, 1972, 1973, have shown that the brook
trout is extremely sensitive to minute cadmium concentrations
in water. They reported that 50 % of a group of this type of
fish died in 3 days, when exposed to a level of 5 ng/g of cad-
mium in 10 % sea water at 20°C. Hemorrhagic necrosis and
vascular abnormalities of the testicles were not observed. When
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5- 29
this type of trout was exposed to 25 ng/g of cadmium for 24 hours
in soft fresh water (8-12 C) the testicles showed marked discol-
oration. Histological examination revealed extensive hemorrhagic
necrosis and disintegration of lobule boundary cells. When
exposed to 10 ng/g of cadmium, 7 out of 8 brook trout examined
immediately post mortem showed similar injury, though less
extensive. In vitro experiments with tissue from fish exposed
to cadmium showed changes in testosterone metabolism in rela-
tion to control animals..The authors also performed several
experiments with testicular tissue incubated together with cad-
mium in vitro. The results gave conclusive evidence that cadmium
directly affects testicular steroidogenesis in the brook trout
in vitro. The results of Sangalang and O'Halloran are also of
interest in relation to the theory earlier advanced, namely
that cadmium would only have a destructive effect in species
with scrotal testicles. They showed that cadmium can also exert
an effect on testicles of the brook trout, which has abdominal
testicles. It seems thus, that scrotal testicles with their
complicated pampiniform plexus, are not the only type of
testicles affected by cadmium.
Abe, Itokawa, and Inoue, 1972,gave groups of mice consisting of 5-11
animals single intraperitoneal injections of cadmium chloride cor-
responding to 3 mg Cd/kg body weight..Six of the groups of mice were
pretreated 24 hours earlier with intraoeritoneal injections of
0.6 mg Cd/kg body weight, 5 mg manganese/kg body weight, 2 mg
zinc/kg body weight, 1 mg vitamin C/kg body weight, 0.5 mg
vitamin B-^/kg body weight and in the last group thiamin propyl-
disulfide (TPD). Seven days after the cadmium injection the
animals were killed and compared with a control group consisting
of 11 mice. Cadmium alone resulted in testicular atrophy and
congestion as well as splenic hypertrophy, kidney atrophy and
a decrease in hematocrit. Zinc and magnesium concentration in
testis decreased whereas the zinc concentration in liver and
the cadmium concentration in various tissues increased as
compared to the control group. Pre-administration with cadmium
could prevent the anatomical changes in the organs and the de-
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5-30
crease in hematocrit was limited. The other pre-treatment
procedures could not prevent the anatomical changes but the
ability to prevent decrease of hematocrit was similar to that
afforded by cadmium pre-treatment. The variations in metal
concentration in tissues are hard to evaluate as the analytical
method consisted of dry ashing of the samples, dissolution of
the metals in the ash with diluted nitric acid and direct
analysis of this acid in atomic absorption spectrophotometry
without the use of deuterium background correction.
In a report by Sarkar and Mondal, 1973, it was shown that a
single subcutaneous injection of cadmium chloride (5 mg/kg body
weight, corresponding to 3 mg Cd/kg body weight) caused acute
damage to testicular tissue in pigeon, and that this effect
could be prevented by administration of zinc salt (40 mg zinc
acetat per kg). This report too favors the assumption that not
only the mammalian testicle, but also testicles of other species,
are sensitive to cadmium, and that scrotal testicles are not
necessary in order for the effect to occur.
It was mentioned in CITE, 2nd ed., that susceptibility to cad-
mium induced testicular necrosis was variable among strains of
mice. In a study by Taylor, Heiniger and Meier, 1973, a genetic
analysis of this resistance to cadmium induced testicular damage
was performed. The pattern of resistant versus susceptible strains
of mice (earlier reported by Gunn, Gould and Anderson, 1965) was
confirmed, and by mating different types of strains, a dominance
or partial dominance of susceptibility over resistance was
demonstrated. From the pattern of resistant versus non-resistant
strains (where there was a clear distinction between resistant
and susceptible strains), the authors postulated that a single
major gene may account for the difference in susceptibility.
From further mating studies it was concluded that resistance to
cadmium-induced testicular damage is determined by a single,
recessive, fully penetrant gene. The strain distribution pattern
of this gene shows that it is not another manifestation of some
other known genes.
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Dishon et al. , 1972, have shown that urine of rats with ischemia
or toxic (cadmium chloride induced) testicular necrosis contains
testis specific antigenes. Liver and kidney specific antigenes
were also excreted in the urine of animals injected subcutaneous-
ly with cadmium chloride (18-25 mg CdCl2/Kg = 11-16 mg Cd/kg).
In a paper by Koskimies, 1973, the effect of cadmium on the
protein composition of fluids in rete testis and seminiferous
tubules has been studied. The author showed that serum protein
concentration, mainly albumin, increased in the rete testis fluid
already 10 minutes after cadmium injection. In the semiferous
tubules, such an increase was not found until 2 hours after
cadmium administration. The rapid rise of protein content of the
rete testis fluid was considered to reflect changes in the
permeability of the capillaries and/or epithelium there. The
time difference between the reaction of the rete testis and
seminiferous tubules supports the view that rete testis is the
most vulnerable part of the intratesticular duct system.
0
A study was performed by Ray and Chatterjee, 1973, on the effects
of reserpine and adrenalectomy on the action of cadmium on scrotal
and cryptordial testes in the rat. Cadmium (cadmium chloride
4.5 mg/kg body weight: 2.8 mg Cd/kg body weight) was shown to
have a clear effect on the weight of the cryptordial testicle
whereas this effect was blocked by administration of reserpine
or adrenalectomy. The authors suggested that a prerequisite for
the cadmium-induced injurious effect on the vascular epithelium
would be that appropriate amounts of catecholamine are available.
In CITE, 2nd ed., the two prevailing theories to explain
the cadmium-induced testicular i-e.crosis were outlined.
These two theories rested upon 1. circulatory failure
due to vascular damage, and 2. decreased utiliza-
tion .of cadmium. It was further evident from the discus-
sion given in CITE, 2nd ed., that the majority of the researchers
who have studied cadmium-induced testicular damage now seem to
agree that the primary mechanism of cadmium action centers upon
the vascular system and the capillaries in the testicles.
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Lee and Dixon, 1973, gave an account of experimental findings
with regard to cadmium distribution in the testicles as well
as the effects of cadmium on such parameters as thymidine uptake
into spermatogonial cells, incorporation of uridine and L-leusine
into spermatides etc in cadmium exposed mice. They also had groups
of mice exposed to combinations of cadmium and zinc. They inter-
preted their data as favoring a primary action of cadmium on the
utilization of zinc by the spermatogenic cells, as well as an
inhibition of DNA synthesis by spermatogonial cells.
The following methodological consideration may give their data
a different interpretation. The authors mentioned that the
distribution of cadmium in the testicles was studied by velocity
sedimentation cell separation technique, as well as by autoradio-
graphy. With regard to the first mentioned technique, it is not
possible to evaluate to what extent elongated spermatides and remnants
of interstitial tissue, which will also be present in the prepara-
^tions, could be separated. Such a differentiation is of importance,
but a detailed discussion of this problem has not been given in the
report, meaning a possibility that the fraction designated as "late
elongated spermatides" also could have contained some material from
the interstitial part of the testicle. With regard to the auto-
radiographic technique used by the authors, the following can be
said: The method included fixation in Zenker-formol solution, and
paraffin embedding and sectioning at 5 microns. The technique
evidently was a completely wet technique including an acid fixative,
providing abundant opportunities for cadmium to be dissolved and
displaced in the specimens before the actual autoradiography
was performed. The data thus cannot be considered reliable.
The difficulties involved in connection with autoradiographical
studies with cadmium have been pointed out by Berlin, Hammarstrom
and Maunsbach, 1964, as well as by Nordberg, 1972 . The latter
author showed that regardless of type of administration of
cadmium, the cadmium in the testicles will be localized pre-
dominantly in the interstitial tissue of the testicles. Nordberg
instead chose dry techniques and took care not to dissolve
Cadmium from the specimens before autoradiography was performed.
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5-33
Concerning data on effects of cadmium also reported by Lee
and Dixon, they are not conclusive with regard to the primary
site of action of cadmium, and in view of the equivocal findings
concerning the distribution, the paper cannot be said to give
good support for the theory of primary action of cadmium on the
spermatogenic epithelium. It must therefore still be considered
most likely that the primary action is upon the vascular part
of the testicles.
5.5 TERATOGENIC EFFECTS
Transplacental transfer of cadmium and the effect of cadmium
on the placenta have been given comment in Chapter 4 of this
report. It was concluded that the transplacental transfer of
cadmium will probably be dependent on factors such as time of
administration in relation to gestational age, route of admin-
istration and cadmium dose. After small oral or subcutaneous
doses, cadmium does not accumulate in the fetus and the uptake
in the placenta is small. When large intravenous injections of
cadmium are given in the earlier parts of pregnancy, sub-
stantial transplacental transfer occurs, whereas in the lat-
ter part of pregnancy just prior to delivery, transplacental
transfer of cadmium is negligible. When cadmium is administered
late in pregnancy, the placenta is destroyed. A syndrome
similar to a toxemia of pregnancy can be produced by cadmium
injected during this last part of pregnancy. The following sec-
tion will deal with teratogenic effects of cadmium only.
The first studies of the effects of cadmium on embryogenesis
were performed on the golden hamster. Intravenous injection of
cadmium into pregnant animals of this species during the '8th
day of gestation brought forth teratogenic effects, especially
on the facial architecture (Ferm and Carpenter, 1968) . Cleft
lips and palate as well as other types of facial defects were
induced. The teratogenic effects of cadmium and other metals on
mammalian embryos have recently been reviewed by Ferm, 1972.
Since the effects of cadmium, especially on testicles, have
been shown to be counteracted by zinc, Ferm and Carpenter, 1968
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5-34
also tested whether simultaneous injection of zinc could protect
against the teratogenic effects of intravenously injected cadmium.
The results are shown in Figure 5:9. It is evident from the
figure that the simultaneous injection of zinc will protect
against the teratogenic effects of cadmium, it has also been
shown that cobalt protects against the toxic 'effects of cadmium
upon sensory ganglia and testes (Gabbiani, Gregory and Baic,
1967). A similar protective effect of cobalt against the teratogenic
effect of cadmium was tested by Perm and Carpenter, 196R, but
it failed to occur. The protective effect of zinc is not due to
influence of zinc on the transplacental transfer of cadmium, since
this transfer is not influenced by cadmium (Ferm, Hanlon, and
Urban, 1969). Ferm, 1972, interpreted the observations as sug-
gesting that cadmium acts directly upon embryonic tissue by
interfering with zinc-metalloenzymes such as carbonic anhydrase
and alkaline phosphatase.
When selenium is administered at or near the same time as cadmium,
by intravenous injection in the golden hamster, it protects
against the teratogenic effect of cadmium (Holmberg and Ferm,
1969). This protection by selenium occurs only when the time
interval between the injection of the two metals is half an
hour or less.
The simultaneous injection intravenously of inorganic salts of
lead and cadmium to the golden hamster protected the embryo from
the teratogenic effect of cadmium, and no cleft lips or palates
were found in such embryos. On the other hand, cadmium appeared
to potentiate the teratogenic effect of lead, producing more
severe malformation of the caudal part of the embryo, a malforma-
tion typically produced by lead. Lead only, for example, produced
only tail defects, whereas the combination of lead and cadmium
produced embryos with severe malformation of the lower extremities
including sympodia, as well as umbilical hernias. Neither of
these types of malformations was noted when either of these two
teratogens was used alone (Ferm and Carpenter, 1967, Ferm, 1969).
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5-35
In a later report by Perm, 1971, other congenital malformations
were noted in the cadmium-exposed golden hamster embryo, such as
limb defects including amelia and phocomelia. Further studies on
the skeletal malformations resulting from cadmium treatment in
the hamster were reported by Gale and Ferm, 1973. The technique
followed was the one described by Ferm, 1971. The dose of
cadmium was 2 mg/kg of cadmiumsulfate (3 CdSO. 8 H~O) injected
intravenously on the 8th and 9th day of gestation, corresponding
to the time of major organ differentiation in the golden hamsters.
Skeletal malformations were examined after staining with alizarin.
Skeletal abnormalities were reported in the form of changes in
the ossification center of the skull, vertebral column, ribs,
hyoid bone and sternum. Skeletal malformations of the fore limb
and hind limbs were also observed at a higher frequency in the
cadmium injected groups compared to controls.
Mulvihill, Gamm and Ferm, 1970, have shown that the palatal clefts
induced by cadmium in the golden hamster can best be explained by
mesodermal deficiencies in the palate region. These abnormalities
are characterized by deficiencies in formation and delays in bone
ossification.
All of the above mentioned teratogenic effects of cadmium have
been studied in the golden hamster, and induced by intravenous
injection of cadmium. Chernoff, 1973, studied the teratogenic
effects of subcutaneous injections of cadmium in rats. He used daily
injections of 4-12 mg of cadmium chloride per kilogram of body
weight (2.5-7.5 Cd/kg). The injections were given on 4 consec-
utive days beginning on day 13 to 16 of gestation. This treatment
resulted in a dose-related rise in the fetal death rate, decrease
in fetal weight and increase in the rate of anomalies, which
included micrognathia, cleft palate, club foot, and small lungs.
Ishizu et al., 1973, gave pregnant mice subcutaneous injections
of cadmium as the chloride in doses of 0, 0.33, 0.63, 2.5 and
5 mg/kg on the 7th day of gestation. A dose dependent relation-
ship was found from 0.63-5 mg/kg of Cd, as seen in Table 5:16.
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5-36
The no-effect dose with regard to malformation in this study was
found to be 0.33 mg/kg.
Barr, 1973, has shown teratogenicity in two stocks of Wistas rats
from i.-p. injection of CdCl,, 16 ymol/kg body weight (1.8 mg Cd/kg) .
There was a much more prominent effect on fetal mortality in the
"S"-stock than in the "C"-stock of rats. The type of teratogenic
effect observed also varied with stock of rats. For example, there
was a 55 % rate of diaphragmatic hernia in the "S"-stock when
injections were made on day 10 of gestation. The corresponding
rate in "C"-stock was only 0.8 %. The types of teratogenic ef-
fects observed were completely different from those observed in
the hamster.
Since all of the above mentioned investigations on rats and golden
hamsters were performed by injection of relatively large doses
of cadmium as a single injection or as a repeated administration
for a few days duration, the effect may be classified as acute
or subacute. It is known from experience with various other
teratogenic agents that inter-species variation is large for
teratogenic effects. The interpretation of the observed effects
with regard to possible teratogenic effects in man is therefore
difficult because of the limited number of species studied. An
additional difficulty for the interpretation is the different
mode and duration of exposure in relation to the human situation
with regard to environmental exposure to cadmium, which includes
mainly chronic or subchronic exposures. Acute oral and inhala-
tion exposures to human beings also exist, but exposure by the
injection route is not applicable to the human being.
Because of the different type of exposure, 'the experiments by
Cvetkova, 1970, and Schroeder and Mitchener, 1971, are of particular
interest. Cvetkova, 1970, exposed female rats via the respiratory
route to cadmium sulfate (3 mg/m ) during pregnancy. On day 22 of
gestation examination of half of the material was performed. Fetal
weight was lower than in controls, but no evidence of fetal
mortality was found. The other half of the material was allowed
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5-37
to be born. The weight of the newborns was lower than that of
controls. The offspring of the cadmium-exposed rats also dis-
played an increased perinatal mortality.
Schroeder and Mitchener, 1971, exposed mice (Charles, Rivers C.D.
strain) to 10 yg/g cadmium in double deionized water. The controls
were given deionized water without addition of cadmium. The diet
contained the following elements ,(yg/g wet weight): zinc 23.2;
copper 1.95; manganese 12.25; cobalt 0.18; molybdenum 0.4-5;
selenium 0.056; and chromium 0.60. Five pairs of mice were
taken at the time of weaning, placed in separate cages and given ri
cadmium in drinking water continuously. The mice were allowed to
breed as often as they normally would up to 6 months of age. At
weaning time pairs were randomly selected from the first litter
(FlA generation), from the second litter (FIB) and allowed to
breed ad libitum to produce F2-generations. Pairs were selected
at random from the first F2A litters and allowed to breed the
F3-generation. Experiments were terminated when the strain was
obviously dying out or when 3 generations had been weaned. Control
animals were bred similarly. The results with regard to cadmium are
seen from tables 5:13 and 5:14. It is seen that cadmium was toxic
to breeding mice. Congenital abnormalities included sharp, angula-
tion of the distal third of the tail, this abnormality appearing
in 5 litters, comprising 41 of 255 offspring (16.1 %) of the
Fl and F2A generation. There were also 34 runts (13.3 %) in the
offspring living beyond weaning, 87 deaths before weaning (30.5 %),
2 maternal deaths and 2 dead litters. Three of 5 pairs failed to
breed in the F2B generation and. the experiment was discontinued.
These data from Schroeder and Mitchener show that the type of
abnormality induced by long-term oral exposure was different from
those induced in earlier studies on hamsters and rats. They also
showed a significant difference in comparison with their own
controls for several parameters. These experiments as well as those
of Cvetkova, 1970, are of particular importance, as stated above,
because the type of exposure employed is similar to what could be
met in the human situation. Consumption of drinking water or drinks
prepared from water containing as much as 16 yg/g of cadmium for
prolonged periods of time has been reported for school children in
Sweden (Nordberg, Slorach and Stenstrom, 1973).
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5-38
In short, teratogenic effects of cadmium have indeed been demon-
strated. However, the majority of the experiments have been per-
formed with injection of relatively large doses of cadmium over
a few days, only a few experiments having involved long-term oral
administration. The experiment by Schroeder and Mitchener, 1971,
in mice, did indicate that relatively small concentrations of
'cadmium in drinking water could exert an effect. It is therefore
important to continue to look for teratogenic and embryotoxic effects
in inhalation and oral exposures in various experimental animals.
In a study of women occupationally exposed to cadmium in the
U.S.S.R, (Cvetkova, 1970) a decreased weight of babies was found.
More such studies would be of great interest. Neither this study,
nor the animal studies at hand, yet provide sufficient data for
a detailed evaluation of the risks for embryotoxic and teratogenic
effects of cadmium in man.
5.6 ACUTE SYSTEMIC EFFECTS OF CADMIUM INJECTION - STUDIES IN .
RELATION TO CHRONIC EFFECTS AND THE INFLUENCE OF
METALLOTHIONEIN
In earlier parts of this report as well as in CITE, 2nd ed.,
various effects of acute and chronic cadmium exposure have
been reviewed. By far greater emphasis has been placed on
chronic effects because these effects may arise at relative-
ly low daily dose levels, which may be comparable to actual
environmental exposures. Acute effects in experimental animals
after injection of cadmium salts have been given only brief
mention with the exception of the somewhat detailed treatment
on testicles. Although effects demonstrated by injection
of relatively large doses of cadmium compounds may be of
limited practical value, mechanisms of a fundamental interest
to metal toxicology have been revealed while investigating
them. These mechanisms with all probability will be of
importance for the effects elicited by the cadmium levels
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5-39
met with in the environment. A brief discussion of these
mechanisms therefore will be given in the following.
Acute systemic effects of cadmium (reviewed in the foregoing
section of this report and in CITE, 2nd ed.) include transient
effects on the cardiovascular system with changes of blood
pressure/ which have been reported after intravenous in-
jection of cadmium in doses 0.02 to 2 mg/kg, testicular
effects at dose levels of 0.1 to 2 mg/kg, effects on non-
ovulating ovaries in young female rats, placental necrosis
in pregnant mice and rats at dose levels 2 to 4 mg/kg
and lesions in sensory ganglia at the same (2 to 4 mg/kg)
dose levels. At larger doses (2 to 6 mg/kg) liver damage
can occur, the higher of these doses being, however, in
the lethal range. In this lethal range renal damage can
occur, but it is of a different nature from that produced
by low level long-term exposure.
Lesions caused by chronic exposure to cadmium are quite dif-
ferent from those produced by acute injection experiments
mentioned above. Renal tubular impairment with excretion
of low molecular weight proteins is considered to be the
critical effect in long-term low level exposure to cadmium
(see earlier chapters of this report and CITE, 2nd ed.).
Such proteinuria, first described in industrial workers
(Friberg, 1950), could be reproduced in experimental ani-
mals (Friberg, 1950; Dalhamn and Friberg, 1957; Bonnell,
Ross and King, 1960; Axelsson and Piscator, 1966; Axelsson,
Dahlgren and Piscator, 1968; Nordberg and Piscator, 1972;
Nishizumi, 1972). It was not certain as to whether the
acute effects of cadmium injection mentioned above could
also arise after chronic exposure. With regard to the
testicular damage, Nordberg, 1972 , when studying this
question in detail, found no testicular necrosis after
long-term exposure to cadmium although higher concentrations
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5-40
accumulated in the testicles at the same site (interstitially)
as in acute exposure (Nordberg, 1971, 1972 ) . Testicular
damage thus does not seem to be a part of the syndrome
of chronic cadmium intoxication at the stage when tubular
proteinuria first appears.
Testicular damage. Nordberg, 1971, 1972 , performed a
series of experiments to test a theory implying a protect-
ive mechanism of metallothionein against acute manifesta-
tions of cadmium intoxication. Doses of 1 mg Cd/kg or
higher by the subcutaneous route gave rise to testicular
damage in CBA mice (Nordberg, 1971). The cadmium concentra-
tion in the testicles at such exposure was about 0.3 yg/g.
It was also shown (Nordberg and Piscator, 1972; Nordberg,
1972 ) that CBA mice exposed to cadmium (0.25 mg Cd/kg
or 0.5 mg Cd/kg 5 days per week for half a year by the
subcutaneous route) had evidence of renal tubular impairment
after about 5 months of exposure. These mice underwent
no testicular necrosis similar to the one observed in
the groups given only a single injection of cadmium (1
mg/kg), in spite of much higher concentrations of cadmium
(6-7 yg/g) being present in the testicles. A possible
explanation for the difference in tolerance of testicular
tissue between acute and chronic exposure was the binding
of cadmium to metallothionein. Nordberg, 1971, made the
following experiments to> elucidate this question:
1. In mice given pretreatment by 12 daily subcutaneous
doses of cadmium chloride (0.25 mg Cd/kg) prior to a larger
subcutaneous dose (1 mg Cd/kg), all animals had histo-
logically normal testicles whereas mice given 1 mg Cd/kg,
but no pretreatment, had testicles which were severely
damaged. The protection offered by pretreatment is in
accord with the theory implying metallothionein as a pro-
tective agent.
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5-41
2. Two groups of animals, one group pretreated as stated
above and one non-pretreated group, were both given a
single subcutaneous dose (1 mg Cd/kg body weight) of cadmium
109
chloride tagged with Cd. By centrifugation and gel
chromatography it was found that a larger part of the
radioactivity from the 1 mg/kg dose was incorporated into
a protein of the size of metallothionein in the pretreated
animals than in the non-pretreated ones.
3. In another experiment the same total subcutaneous dose
(1.1 mg/kg) of cadmium was given to different groups of
animals. The dose was divided into different proportions
between metallothionein-bound cadmium and cadmium chloride
in the various groups of animals. In such groups given
0.4 or 0.6 mg cadmium per kg body weight as metallothionein-
bound cadmium the testicles were usually normal. In groups
of mice.given only 0.2 mg Cd/kg as metallothionein-bound
cadmium (and 0.9 mg Cd/kg as cadmium chloride) moderate
to severe damage was seen. In mice given no metallothionein-
bound cadmium (given 1.1 mg Cd/kg as cadmium chloride)
the testicles were completely damaged.
In summary it may be said that Nordberg, 1971, 197?
has shown that metallothionein is involved in the pro-
tection of the testicles against necrosis in more prolonged
exposures, it is likely that metallothionein acts similarly
with regard to other acute effects of cadmium, examples
of which have indeed been put forth by several authors.
However, metallothionein may also be involved in elicita-
tion of damage in long-term exposure to cadmium (see sec-
tion 4.4).
Liver effects. It was shown already by Piscator, 1964,
that cadmium in the liver of experimental animals exposed
to this metal is to a large extent bound to metallothionein.
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5-42
This has later been confirmed by a number of authors (Shaikh
and Lucis, 1969, 1970; Wisniewska-Knypl and Jablonska,
1970; and Nordberg, Piscator and Lind, 1971) . Nordberg,
Piscator and Lind, 1971, reported markedly decreased liver
weights and death in mice given 3 mg Cd/kg body weight as
cadmium chloride. These effects were discussed in relation
to the appearance of cadmium binding to metallothionein
in the liver.
Further data relating effects of cadmium on the liver
and binding of the metal to metallothionein have been
supplied by Winge et al., 1973. These authors gave groups
of animals 0.5, 1, 2, 2.5, 3, 4 or 6 mg Cd/kg body weight
as cadmium chloride daily for 6 days. Animals receiving
0.5 and 1 mg Cd/kg exhibited no morbidity or mortality
whereas animals in the 2 and 2.5 mg Cd/kg groups showed
obvious morbidity. 2/3 of the animals receiving 3 mg/kg
died by the 6th injection day while all of those given
4 mg Cd/kg or more died. Surviving animals were all killed
on the 6th day whereupon the livers were examined by histo-
logical techniques and by gel chromatography. At injection
levels of 0.5 to 1 mg Cd/kg cadmium was discovered to
be bound almost exclusively to metallothionein. As the
injection dose was increased, more cadmium accumulated
in the liver, and protein fractions of high molecular
weight acted to bind cadmium. The histological examina-
tion revealed no liver abnormalities in animals of the
0.5 and 1 mg Cd/kg groups. In the 2, 2.5 and 3 mg Cd/kg
groups degenerating hepatocytes were seen. The authors
concluded that non-metallothionein-bound cadmium was cor-
related to hepatic damage. As in the studies by Nordberg,
Piscator and Lind, 1971, an evident correlation between
clinical morbidity and absence of binding to metallothionein
was witnessed.
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Unger and Clausen/ 1973, found a dose-related inhibition of
cytochrome P-450 activity after a single i.p. injection. The
authors noted that the effect diminished when the interval
between injection and study of enzymatic activity was in-
creased. This was ascribed to the protection offered by syn-
thesized metallothionein.
Effects on glucose tolerance. As stated in earlier parts
of this report/ the pancreas accumulates considerable
amounts of cadmium (Friberg, 1957; Smith/ Smith and McCall,
1960; Ishizaki, Fukushima and Sakamoto, 1970; .Nordberg and
Nishiyama,' 1972) . Data on pancreatic functions in long-
term exposure are sparce. Murata et al., 1970, have reported
changes in the excretory function of the pancreas in Itai-
itai patients. More recently/ Ghafghazi and Mennear, 1973/
reported on effects of acute and subacute cadmium administra-
tion on carbohydrate metabolism in mice. It is known from
earlier studies (Friberg and Odeblad, 1957) that cadmium
is equally concentrated in the exocrine and endocrine
parts of the pancreas. Ghafghazi and Mennear, 1973, injected
2 to 6 mg/kg of cadmium acetate intraperitoneally to mice
and observed a dose-related increase in blood glucose
concentration. Administration of cadmium to adrehalect-
omized animals failed to evoke hyperglycemia, showing
that this effect of cadmium is mediated through the adrenal
glands. The same investigators also learned that the glucose
tolerance was diminished after cadmium administration
in the mice with adrenal glands as well as in adrenalecto-
mized mice. Glucose intolerance was shown to be associated
with a decreased pancreatic secretory activity of insulin
measured as serum immunoresponsive insulin. The administra-
tion of 4 mg/kg of cadmium daily for 4-14 days produced
resistance to cadmium-induced hyperglycemia. This subacute
treatment did not produce changes in resting blood glucose
levels nor did it produce a decrease in glucose tolerance. A
-------
5-44
significant reduction in circulating serum insulin was
detected after subacute cadmium administration, which
may be related to an increased renal excretion of glucose.
The resistance against hyperglycemia built up by the repeated
treatment was explained by the authors as stemming from
the induction of metallothionein by the acute doses. They
postulated that this protein prevented the effects on
the pancreatic isles. This may be in accord with the ob- .
servation that the main part of the pancreatic cadmium
in mice during long-term exposure to cadmium was in the
metallothionein fraction (Nordberg and Nordberg, 1973) .
It has been mentioned previously that it is not possible
to induce renal tubular effects by injecting a single
large dose of cadmium. By injection of repeated large
doses over a limited period renal effects can be induced,
but these effects differ morphologically from those observed
after more long term dosage of smaller daily doses of
cadmium (Kawai, Fukuda and Kimura, 1975).
Renal effects. Studies of the influence of cadmium on the
synthesis of 1,25-dehydroxycholecalciferol in vitro by
kidney mitochondria have been described previously (Feldman
and Cousins, 1973, section 5.2). These authors as well as
Kimura et al., 1974,showed that metallothionein prevented
the inhibitory effect of cadmium upon this process.
By combining cadmium injection with various chelating agents
like 2,3-dimercaptopropanol (BAL) (Oilman et al., 1946,
Tepperman, 1947j Niemeier, 1967) and ethylene diaminetetra-
acetic acid (EDTA) (Friberg, 1956; Eybl, Sykora and Mertl,
1966) , an increased renal toxicity and an increased renal
uptake of cadmium may be induced. Injection of a cadmium-
cysteine complex (Gunn, Gould and Anderson, 1968) can in-
-------
5-45
duce a selective renal tubular injury and a prominent accu-
mulation of cadmium in the kidney.
Recently Gieske and Foulkes, 1974, administered a mixture
of cadmium chloride (10 ymol Cd/kg = 1.1 mg Cd/kg) and
mercaptoethanol (350 ymol/kg) intravenously to rabbits
and studied the resulting renal damage by various renal
function tests. Glomerular filtration rate, p-aminohippu-
rate clearance (CPAH) and extraction of p-aminohippurate
(E ) were severely depressed in animals given Cd-mer-
lr /T-tl
captoethanol. The filtration fraction (GFR/plasma flow)
also decreased as well as reabsorption of amino acids.
The site of inhibition of amino acid reabsorption was
considered to be the luminal membrane of the tubular
cells. On the other hand the tubular ability to reab-
sorb gluocse was unaltered when corrected for changes
in GFR, thus indicating that the effect of Cd-mercapto-
ethanol on the kidney was relatively specific.
Since mercaptoethanol does not occur in appreciable
amounts in the body, the data presented by Gieske and
Foulkes,1974, do not necessarily have a bearing on the
type of renal damage induced by chronic cadmium poi-
soning when no chelating agents are administered to-
gether with cadmium. But it can not be said for certain
that the tubular impairment is not similar, since the
mechanism for elicitation of the chronic type of les-
ion may involve transport of cadmium bound to metallo-
thionein. However, it remains to be shown that the
types of renal lesions produced by metallothionein-
Cd and mercaptoethanol-Cd are the same and in turn
correspond to those in chronic cadmium poisoning.
-------
5-46
That a renal tubular damage can be induced by injection of metal-
lothionein-cadmium has been shown by Nordberg, 1971, and Nordberg,
Goyer and Nordberg, 1975. The last mentioned authors injected
metallothionein-bound Cd in doses between 0.4 - 1.5 mg Cd/kg to
mice and demonstrated prominent tubular damage by histological
techniques. The glomeruli were not affected.
These authors as well as Cherian and Vostal, 1974, have reported
that more cadmium is accumulated in the kidney and less in the
liver after injection of metallothionein-bound cadmium compared
to injection of cadmium chloride.
The prominent tubular damage is in accord with results from auto-
I
radiographic localization studies indicating that the part of the
metallothionein-bound cadmium that accumulates in the kidney is
localized in the renal tubules. This has been shown in recent
experiments by Nordberg, Nordberg and Pannone (to be published)
109
in which mice were injected i.v. with Cd-labelled homologous
metallothionein and studied by autoradiographical and scintilla-
tion counting techniques. During the first minutes after injec-
tion of metallothionein-bound Cd the main part the cadmium was
accumulated in the kidney and subsequently excreted in the urine.
A considerable part of the cadmium hence was found in the urinary
bladder in the whole body autoradiograms at 20 minutes after in-
jection. After that period the distribution pattern was mainly
unchanged. (The cadmium in the urinary bladder disappeared as the
urine was voided.) Whole body measurements revealed that about
half of the cadmium injected as metallothionein-bound cadmium had
been excre'ted during the very first period after injection, while
the cadmium remaining in the body (localized mainly in the kidney)
had a long biological half-time.
These results are in accord with results reported by Vostal, 1975,
109
who found that about half of Cd-binding protein (metallothionein)
injected i.v. or in the renal artery of rats was excreted in the
urine.
-------
5-47
Summary and conclusions
The protective action of metallothionein against various acute
effects of cadmium has been shown with regard to such effects on
various organs like testicles, liver and certain aspects of
pancreatic and renal function. Such studies have been reported
both on the organ and subcellular level.
Whereas metallothionein thus has a protective role against these
acute manifestations of cadmium toxicity, it may be involved in
the elicitation, of the renal tubular impairment seen in chronic
cadmium intoxication.
The above mentioned recently obtained results with regard to the
distribution and toxicity of metallothionein-bound cadmium are
partly confirmatory and partly contradictory to previously
advanced theories concerning the mechanism for renal toxicity
and excretion of cadmium in chronic cadmium poisoning. (These
theories are reviewed in CITE 2nd ed.). It has been shown that
metallothionein can act as a carrier for cadmium, increasing its
accumulation in the kidney and giving rise to renal tubular
damage. This is in accord with previous theories. However, it has
also been shown that cadmium can be excreted in the urine, pre-
sumably at dose-levels of metallothionein-bound cadmium giving
rise to no evident renal tubular damage. This is not in accord
with previous theories. The observations supporting this last
mentioned statement are not conclusive and more data are needed
for a definite statement.
5.7 CARCINOGENIC AND GENETIC EFFECTS
5.7.1 Carcinogenic effects
Lucis, Lucis and Aterman, 1973, studied the tumorogenic effect of
cadmium after a single dose of cadmium chloride (0.02-0.03 mM/kg)
in rats. An initial testicular necrosis developed and after 48
days the first testicular tumor could be shown. Tumors were found
at the site of subcutaneous injection, but not to the same extent
as in the testes. The uptake of cadmium in the testes reached, a
-------
5-48
maximum within about 6 hours after subcutaneous injection whereas
zinc, in contrast, -was accumulated continuously in testes for at
least 20 days. After intrahepatic injection tumors appeared in
the testes though no hepatic tumors developed.
Levy et al., 1973, presented results from a long-term study on
the possible connection between cadmium exposure and cancer of the
prostate. Three groups of rats, 25 ,in each, received a weekly
subcutaneous injection of cadmium sulfate, 0.022, 0.044 and 0.087
mg Cd per rat (average weight 220 g at start and 410 g at end of
exposure) for 2 years. Seventy-five animals received weekly injec-
tion of water and served as controls. Macroscopic and micro-
scopic examinations of the prostate gland were performed.
Neither in exposed animals, nor in controls were any malignant
changes found in the prostate. Leydig cell tumors were found in
testes in 67 % of the controls and 67-77% of the exposed groups.
The authors verified in another experiment that high risk for
tumors of this type is typical for the subline of the C.B.
hooded rats used. In the control group 2 neoplasms were found
in other organs, and in the exposed groups 3 neoplasms. In the
highest exposure group other effects were seen and renal concentra-
tions of cadmium were high. This study has added evidence for
cadmium's having no carcinogenic activity, even at long-term
exposure.
5.7.2 Genetic effects
It was stated in CITE, 2nd ed., that the limited literature
dealing with genetic effects of cadmium was to some extent
contradictory. A study on Drosophila showed no genetic effect,
whereas studies from Japan on Itai-Itai patients had shown in-
creased frequencies of chromosomal aberrations. The need for
studies on people exposed to cadmium, but without complicating
effects as seen in Itai-Itai disease was pointed out.
Bui, Lindsten, and Nordberg, 1975, have presented material in-
cluding both cadmium exposed workers from a Swedish battery factory
and Itai-Itai patients from Japan as well as control subjects
-------
5-49
in Table 5:15. No statistically significant differences in the
frequency of chromosomal aberrations could be found between
cadmium exposed and control subjects in either the Swedish or
Japanese material.
These observations thus are at variance with previous reported
observations from Japan. An explanation for this discrepancy
has not yet been found.
5.8 OTHER EFFECTS
A decrease in hematocrit, hemoglobin and liver-iron was found
by Freeland and Cousins, 1973, in chicks given a diet contain-
ing 75 pg Cd/g. Radioactive iron was introduced into a duodenal
loop whereupon its absorption was found to be decreased. The
authors concluded that at least part of the mechanism involved
in cadmium anemia is a decreased absorption of iron from the
intestines. Copper and zinc concentrations in liver and kidney
were slightly elevated which was interpreted as showing that
these metals were incorporated into the cadmium-binding pro-
tein and deposited at the same place as cadmium.
Cadmium-induced anemia in growing pigs was investigated by
Pond, Walker and Kirtland, 1973. They found decreased hemo-
globin levels with a diet containing 154 ygCd/g. The depres-
sion was prevented by oral or intramuscular iron-administra-
tion.
Chatterjee, Banerjee and Pal, 1973, studied the protective ac-
tion of ascorbic acid on cadmium intoxication in rats. Four
weeks after exposure to cadmium chloride in the diet, corre-
sponding to a dose of 60 mg Cd/kg body weight daily, pronounced
anemia, decrease in growth rate, and liver damage were observed,
When the diet also contained ascorbic acid the resulting anemia
was less pronounced as was the decrease in growth rate. Histo-
-------
5-50
logical liver changes were as prominent among the cadmium-ascorbic
ascorbic acid rats as among the cadmium rats.
Ogawa et al., 1973, studied the influence of cadmium chloride
on the activities of carbon anhydrase, catalase, and hemoglob-
in level. Tap water containing 146 yg Cd/g was given ad libitum
in 5 experiments to groups of 5 mice for 10, 20, 30, 60 and 90
days respectively. Control groups were given tap water without
cadmium. Carbonic anhydrase activities in liver, kidney and
blood were diminished significantly already after 20 days. De-
crease in catalase activity was seen first after 60 and 90
days of administration of cadmium.
Diamond, Jedeikin, and Kench, 1973, found that cadmium in
low concentrations stimulated, but in higher concentrations
inhibited, tryptophan oxygenase.The studies were carried
out in vitro.
The impact of prolonged cadmium exposure in rats (1 mg of
cadmium chloride/kg body weight daily during 45 days
intraperitoneally) was investigated by Singhal et al.,
1974). The injections produced significant increases
in the activity of liver pyruvate carboxylase, phospho-
pyruvate carboxylase, hexosediphosphatase, and glucose-
6-phosphatase compared with control values. Withdrawal
of cadmium exposure for 28 days failed to restore the
enzyme activities to the control values. In treated
rats, there was an increase in blood glucose and urea,
contrasting with a remarkable decrease in the amount
of liver glycogen, the latter being an event which per-
sisted after the 28-day withdrawal. Excretion of pro-
tein and glucose exceeded that of controls as indicated
by Combistix and Dextrostix tapes. The authors discussed
the possibility that the increase in urinary protein
and glucose had an enzymatic basis, at least in part.
-------
5-51
Mills and Dalgarno, 1972, studied copper and zinc status of
pregnant ewes and lambs receiving dietary concentrations of
cadmium (0.7, 3.5, 6.1, and 12.3 yg/g) As in earlier experi-
ments with rats, chicks, goats and pigs (Bunn and Matrone,
1966; Hill and Matrone, 1970? Anke et al., 1971), the.
cadmium treated ewes showed a decreased copper concentration
in liver. This decrease was pronounced at the high dose
level but could be shown also after medium exposure.
As could be expected, lamb liver at birth did not show
any increase in cadmium concentration. Copper concentration
in liver was reduced in lambs whose mothers had received
7.1 or 12.3 yg Cd/g in the diet. What complicates the
interpretation of the studies is that the diet (herbage)
contained high amounts not only of cadmium but also
of zinc. The zinc concentration was considerably more
than the threshold concentrations (200-400 yg/g) above
which it induces clinical effects attributable to copper
deficiency in rats and chicks (Bunn and Matrone, 1966;
Hill and Matrone, 1970).
-------
TABLE 5:1
MAIN PATHOLOGICAL FINDINGS AFTER EXPERIMENTAL CHRONIC CADMIUM POISONING IN RATS
(From Kawai and Fukuda, 1974).
Cd
cone in
drinking
water
yg/g
10
50
100
200
200
Expo-
sure
time
months
8.5
II
II
8.5
18
KIDNEY
pathol .
finding
• -i i
—• +
+
+
E.A.
++
F.D.
Cd
yg/g
12.3
38.4
100.1
156.3
136.8
Cd
amount
yg
41
142
303
478
467
BONE
Atrophy
+
+
+
+
++
Corti-
cal
thick.
%
27.6
26.3
23.7
22.0
19.8
Ca
mg/g
129
128
125
113
114
Cd
yg/9
1.07
1.44
2.39
3.48
2.87
LIVER
Cd
yg/g
4.2
29.8
73.1
143.1
234.7*
(A)
Cd
amt.
yg
75
500
987
2064
2283
LIVER +
KIDNEY
Cd total
amt. yg
116
692
1290
2532
2750
A: Atrophy D: Changes E: Edema F: Fibrosis rat SD-JCL^
in
i
in
N>
*29.62/4205
-------
TABLE 5:2
URINARY IMINO ACID EXCRETION IN DIFFERENT PERSONS (From Sano and Iguchi, 1974).
HYP
mg/l
Pro.
mg/l
Total
Free
Bound
Total
Free
Bound
1 2
91 52
51 37
40 15
389 153
144 115
245 38
Itai-itai
Patients,
Fuchu area
3456
117 67 61 212
61 38 38 112
56 29 23 100
927 551 / 933
571 251 4.83 590
356 300 / 343
7
48
40
8.0
234
129
95
Cadmium-
exposed
persons, Ikuno area
123
48 10 246
23 trace 153
25 10 93
L66 57 527
72 28 175
94 29 342
4
12
trace
12
36
trace
36
5
84
58
26
207
153
54
6 7
62 91
38 35
24 56
129 527
56 175
73 342
Cadmium
Workers
123
49 23 6
trace 11 trace
49 12 6
107 74 16
trace 23 trace
107 51 16
4 5
22 20
trace 3
22 17
40 53
tracelS
40 38
Controls
1 2
1 0
trace
1 0
2 0
trace
2 0
in
i
c/i
W
-------
5-54
TABLE 5:3
PRINCIPAL CHARACTERISTICS OF MALE WORKERS (E3) EXPOSED > 20
YEARS TO Cd AND OF CORRESPONDING MALE CONTROL WORKERS (C3)*
(From Lauwerys et al., 1974).
Cd-Exposed Controls
(E3) (Smokers) (C3) (Smokers)
No. of workers
Age, yr
Mean
Median
Height, cm
Weight, kg
No. of cigarettes
smoked per day
Duration of smoking, yr
Duration of factory employment, yr
22
51.5
51.0
168.6
74.4
13.0
28.5
27.8
± 1.4.2
± 0.99
± 1.53
± 1.35
± 1.82
± 1.58
22
51.4
51.0
170.5
76.0
16.6
25.9
29.1
± 1.56
± 0.85
± 2.27
± 1.48
± 1.23
± 2.17
* Values expressed as mean 1 SE.
TABLE 5:4
PULMONARY FUNCTION TESTS IN Cd-EXPOSED (E3) AND CONTROL (C3)
WORKERS* (From Lauwerys et al., 1974).
Cd-Exposed (E3) Controls (C3)
(Smokers) (Smokers)
No. of workers
FVC,
FEV,
J- •
T
0.50
PEFR,
V50,
V
'
liters
o, liters
sec
,
liters/sec
liters/sec
liters/sec
22
3
2
0
7
3
0
.61
.51
.40
.32
.12
.96
± 0
± 0
± 0
± 0
± 0
± 0
.15
.12
.08
.37
.28
.10
Pt
22
4
2
0
8
3
1
.01
.85
.37
.13
.64
.07
+
+
+
+
+
+
0
0
0
0
0
0
.11
.09
.08
.26
.27
.10
< .05
< .05
> .05
< .05
> .05
> .05
• Values expressed as mean - SE.
t Values obtained from Student t-test.
-------
TABLE 5:5
BIOLOGICAL INDICES IN Cd-EXPOSED (E3) AND CONTROL (C3) WORKERS* (From Lauwerys et al., 1974)
Cd-Exposed (E3)
(Smokers)
No. of workers
Cd concentration in urine,
yg/g creatinine
Cd concentration in blood,
ng/g
Y -galactosidase level in plasma,
units/hr/ml
LDH level in plasma,
units/min/ml
Catalase level in plasma,
units/hr/ml
CHE level in plasma,
ymols thiocholine/min/ml
RBC-ACHE ,
ymols thiocholine/min/ml
Hematocrit, %
No. of workers with abnormal urinary
protein electrophoresis
22
31.0 ±
27 ±
97.0 ±
71.0 ±
2.4 ±
2.1 ±
7.4 ±
41.2 ±
15
4
3
5
4
0
0
0
0
.30
.0
.00
.50
.03
.13
.22
.70
Controls (C3)
(Smokers)
22
2.2
7
66.0
58.5
2.4
2.2
8.2
44.8
0
± 0.20
± 1.0
± 5.00
± 2.50
± 0.02
± 0.10
± 0.27
± 0.70
Pt.
< .05
< .05
< .05
< .05
> .05
> .05
< .05
< .05
< .05
* Values expressed as mean ± SE.
t Values obtained from Student t^-test when al 7* a2,
in
i
in
in
-------
TABLE 5:6
PROTEINURIA AND Cd CONCENTRATION IN BLOOD AND URINE OF MALE WORKERS*(From Lauwerys et al. , 1974)
Controls
Pf
Exposed
Normal
Electro-
phoresis
Pj-
Abnormal
Electro-
phoresis
No. of workers
Proteins in urine,
mg/g creatinine
Cd concentration in urine,
yg/g creatinine
Cd concentration in blood,
, ng/g .
50
153
1.72
7
± 8
± 0.15
± 0.7
>.05
<.05
<.05
30
158
11.70
24.7
± 8
± 1.60
± 4.9
<.05
<.05
<.05
19
441
48
33
+
±
.1±
79
10
4
.9
• Values expressed as mean ± SE
t Values obtained from Student t-test when al ^ a2. Each value is inserted between two values
that are compared.
tn
i
In
-------
5-57
TABLE 5:7
INDIVIDUAL RESULTS OF URINE ANALYSIS OF 19 WORKERS IN A CADMIUM
PIGMENT PLANT (Compiled from two studies by Harada 1973, and
Harada et al., 1974).
Exposure time TCA-result Increase in
years globulin fraction
of electrophoresis
0.75
0.75
1.25 ±
1.75 - ±
2.0 - +
2.25
2.25
3.2
3.2
3.4 ±
3.4 ± ±
5.0 - +
5.9 ± +
6.5 - ±
10.5 + +
11.75 + +
13.75 - +
15.5 - +
22.0 + +
-------
5-58
TABLE 5:8
URINARY EXCRETION OF TOTAL PROTEINS, CADMIUM AND 6 -MICROGLOBULIN
IN ITAI-ITAI PATIENTS, OBSERVATION PATIENTS AND .CONTROLS-JAPANESE
FARMERS IN ANOTHER AREA (From Shiroishi et al., to be published).
Itai-itai Observation Controls
Patients Patients
Number of persons 10 32 17
Total protein
(Kingsbury-Clark)
mg/g creatinine 1066 ±402 943 ± 587 64± 148
Cadmium
ug/g creatinine 22.4 ±12.8 8.2±11.9
B9-microglobulin
mg/g creatinine 98.9 ± 33.4 51.1+36.3 0.32+0.5
-------
TABLE 5: 9
AUTOPSY CASES DIAGNOSED CLINICALLY AS ITAI-ITAI DISEASE (From JCajikawa
Name No of Age Sex Time of Bone
Autopsy Autopsy
l.T.M. 3415 62 F
2.T.Y. 3429 62 F
3.T.K. -3616 49 F
*
*
1955 OM +++
OP ++
1955 OM +++
OP ++
1958 Osteitis
fibrosa
Kidney
Pyelonephritis
Arteriosclerosis
Metastatic calcification
Pyelonephritis
Arteriosclerosis
Metastatic calcification
Nephrocalcinosis
Pyelonephritis
Hydronephrosis
4.A.M. 4207 44 F 1963 Osteitis Nephrocalcinosis
* fibrosa with
oseudofracture
5.I.F. 4574 73 F
6.S.M. 5467 61 F
7.S.S. 5313 79 F
1965 OM +
OP +
OS +
TN
1968 OS + Suppurative
OP + pyelonephritis
(Pseudofracture
in X-ray film)
1968 OM +
OP +
OS +
TN +
8.U.T. 73 F 1968 OM ++
OP ±
(ribs)
TN ++
9.H.A. 5677 75 F 1969 OM ±
OP +
OS +
10.E.T.
11.I.S.
6118 68 F
6356 72 F
1971 OM ++
OP ++
OS ±
1971 OP ++
TN ++
TN +++
Arteriosclerosis
OM:
OP:
OS:
TN:
P :
S :
* .
Osteomalacia
Osteoporosis
Osteosclerosis (including healed pseudofracture)
Tubular nephropathy (tubular atrophy and dilatation with
eosinophilic casts, and interstitial fibrosis)
Proteinuria
Glucosuria
Possibly different disorders from Itai-Itai-disease
et al., 1974) .
Parathyroid
Normal
Slightly
hyper-
plastic
Hyperplasia
(adenoma)
Other Organs
Pulmonary congestion and
edema
Pulmonary congestion and
edema
Enterocolitis
Metastatic calcification
Hyperplasia Chronic pancreatitis, Gas-
(secondary?) tritis and colitis, Throm-
(adenomatous) bosis of the portal vein
Normal
Normal
Normal
Normal
Normal
Normal
Normal
Chronic pancreatitis
Chronic hepatitis
Verrucous endocarditis
(Mitral and aortic
stenosis with insuf-
ficiency)
Cancer of the stomach
Cancer of the stomach
Bronchopneumonia
Fibrinous pleuritis (1)
Ulcerative colitis
Anemia
Hypertrophy of the heart
Pulmonary edema
Anemia
Malnutrition
Cause of Duration Address urine
death (Yrs)
Emacia- 12
tion
Emacia- 5
tion
Uremia 10
Portal 5
throm-
bosis!?)
Uremia 12
Cardiac 11
failure
Cancer 8
Cancer 8
Uremia 2
Uremia 16
Suicide 21
by hanging
Fuchu-machi
Fuchu-machi
Tr.umi -machi.
Toyama City
Nyuzen-machi
Yoshikura
(Shimbo),
Toyama City
Yoshikura
(Shimbo) ,
Toyama City
Tonan-kami-
kariyama ,
Toyama City
Fuchu-machi
Fuchu-machi
Shimbo,
Toyama City
Fuchu-machi
P -
P -
P -
S -
P +~-
S -
P +
S -
P +
S -
P +
o _ t/i
to
P +
S -M-
p ++
S ++
P ++
S ++
P ++
s ++
P +
s + +
-------
TABLE 5:10
DOSE RESPONSE RELATIONSHIP BETWEEN DECREASE IN P-450 ACTIVITY AND Cd DOSE (From Unger and Clausen,
1973).
Table 1
Specific P-450 0-demethyl- Statistical evaluation
ation activity (nmoles/mg of mean values compared
liver microsome protein/min) with data of untreated
i.p. administration of
Cd(NO3 )2 ,4HOH in saline
solution
nil
50 mg/kg body weight
10 .mg/kg b.w.
2.8 mg/kg b.w.
1 mg/kg b.w.
100 yg/kg b.w.
10 yg/kg b.w.
100 ng/kg b.w.
10 ng/kg b.w.
1 ng/kg b.w.
0.1 ng/kg b.w.
animals
No. of
animals
4
4
5
2
8
3
8
9
4
10
4
Mean
9.7
Standard
deviation
1.2
Variance-
ratio P(F)
-
Student's
P(t)
-
No. of deaths
within 72
hours
-
- - • - - all dead within
2.6
2.0
5.3
7.9
7.6
7.9
8.2
8.5
9.6
1.2
0.5
1.8
1.7
1.3
3.4
1.0
3.0
3.2
<0.05
<0.05
<0.05
<0.05
<0.05
<0.05
<0.05
<0.05
<0.05
<0.0005
<0.005
<0.025
<0.20
<0.05
< 0 . 3 0
<0.10
<0.40
<0.40
8 hours
none
none
none
none
none
none
none
none
none
en
i
C*
0
-------
5-61
• TABLE 5:11
EFFECT OF CADMIUM CONCENTRATION ON 1,25-DIHYDROXYCHOLECALCIFEROL
SYNTHESIS BY CHICK KIDNEY MITOCHONDRIA (From Feldman and Cousins,
1973) .
Cadmium yMolara % 1,25-DHCC
0 65.0
25 38.0
50 17.2
55 14.5
60 13.3
65 11.1
70 10.4
75 9.7
100 • 6.0
125 2.3
Cadmium solutions were incubated with the mitochondria for 3
min prior to addition of pH]-25-HCC.
TABLE 5:12
PRODUCTION OF 1,25-DHCC IN KIDNEYS OF MICE FED DIFFERENT AMOUNTS
OF CADMIUM (From Kimura et al., in press).
Cd
in diet
ppm
0
10
30
30
300
Feeding
time
weeks
3
3
3
8
3
25-OH-D3
%
68.6
64.4
66.0
69.7
82.1
Percent radioactivity
24,25-(OH)2 -D3 1,
%
1.7
1.2
1.9
2.0
1.6
25- (OH) 2 -D3
%
30.3
34.4
30.5
24.5
16.4
-------
5-62
TABLE 5:13
SUMMARY OF BREEDING EXPERIMENTS IN MICE EXPOSED TO TRACE ELEMENTS
(From Schroeder and Mitchener, 1971).
F, generation
No. of litters
Pair age at first litter, days
Interval between litters, days
Average litter size
M-F ratio
F? generation
No. of litters
Pair age at first litter, days
Interval between litters, days
Average litter size
M-F ratio
F3 generation
No. of litters
Pair age at first litters, days
Interval between litters, days
Average litter size
M-F ratio
Control
19
64
30
11.0
0.94
23
64
28
10.3
1.03
22
62
28
10.5
1.00
Cadmium
14
80.0
34.6
13.1
1.05
11
69
56
9.2
0.78
Discontinued
-------
5-63
TABLE 5:14 .
DEATHS AND ABNORMALITIES OF MICE ,BRED' WHILE .EXPOSED TO TRACE
ELEMENTS (From Schroeder and Mitchener, 1971) .
F, generation
Maternal deaths
Dead litters
Young deaths
Failures to breed
Kunts
No. of mice
F- generation
Maternal deaths
Dead litters
Young deaths
Failures to breed
Kunts
No. of mice
F-, generation
Maternal deaths
Dead litters
Young deaths
Failures to breed
Runts
No. of mice
Total No. of mice
Control
Cadmium
0
0
0
0
0
209
1
0
6
0
2
24»
0
0
i
0
0 .
230
6b7
0
0
39 t
0
25 t
184
2
2
4« t
3
9*
101
.. Discontinued
2«5
Differs from controls by
tP <0,0001
X analysis; P <0.0005
-------
5-64
TABLE 5:15
RESULTS OF CADMIUM ANALYSIS OF BLOOD AND CYTOGENETIC ANALYSIS OF
LYMPHOCYTES FROM CADMIUM EXPOSED AND CONTROL SUBJECTS (From data
by Bui, Lindsten and Nordberg, 1975).
Case Cadmium
No blood
I 1
I 2
I 3
I 4
C 1
C 2
C 3
C 4
E 1
E 2
E 3
E 4
E 5
K 1
K 2
K-3
15
17
16
28
5
6
4
4
24
46
61
30
26
2
3
1
in whole
ng/g
.5
.0
.6
.8
.3
.1
.4
.4
.7
.0
.0
.0
.7
.2
.2
.4
Total No of cells No of cells Mean fre-
analyzed with struct- quency %
ural aberra- .
tions
97
99
100
100
100
82
100
98
100
100
100
100
100
100
100
100
11
6
4
5
7
5
7
4
1
2
2
2
3
5
0
9
6.6
6.0
2.0
4.7
I 1-4 = Itai-Itai disease cases from Toyama prefecture Japan.'
C 1-4 = Control subjects from Toyama prefecture Japan.
E 1-5 = Cadmium exposed workers from a Swedish battery factory.
K 1-3 = Control workers from a Swedish battery factory.
-------
5-65
TABLE 5:16
INCIDENCE OF MALFORMATIONS AMONG FETUSES DUE TO CdCl2 INJECTION,
(From Ishizu et al., 1973).
Dose
Cd
injected
5 mg/kg
2 . 5 mg/kg
0 . 6 mg/kg
0 . 3 mg/kg
Malformed
59.0 %
19.5 %
0.97%
0
0
Dead
17.5 %
12.0 %
11.9 %
9.9 %
9 .7 %
-------
5-66
Hydroxyproline
Proline in urine
Proline in urine
soluble
t
__ proto collagen
f
T
— pro line
A' -pyrroline-5-carboxylatc
glutamic acid
insoluble
collagen
1
2
Accelerated decompo-
sition of soluble
collagen —» Hydroxyproline
Proline metabolism
FIGURE 5:1 Metabolic pathways of imino acids and collagen.
(From Sano and Iguchi, 1974) .
-------
5-67
lib
urines
9i
43
BE
19E
18E
•
I
I
I
23E
NS
10
I
9 8 / 6 5 4 3 ? I
serum
FIGURE 5:2 Electrophoresis on agarose gel of urinary proteins
of four Cd-exposed workers of E3 group: 18E (1,254 mg/g
creatinine), 8E (851 mg/g creatinine), 19E (480 mg/g
creatinine), and 23E (337 mg/g creatinine); and of
urinary (C) (134 mg/g creatinine) and serum (NS)
proteins of control worker. Serum proteins are (1)
albumin, (2) Oj -antitrypsin, (3) otz-zinc-glycoprotein,
(4) a2-HS-glycoprotein, (5) a2-macroglobulin,
(6) haptoglobin, (7) transferrin, (8)3 -lipoprotein,
(9) 3-lc-globulin, and (10) y-globulin. Slight amount
of urinary proteins in control, mainly albumin, not
visible. Cadmium-exposed workers 8E and 18E showed 1,
3, 4, and 7 among their urinary proteins, as well as
low molecular weight proteins a2-microglobulin (5a)
and 32-microglobulin (9a). Only 18E had post-Y-globulin
(lOa). Electrophoretic pattern of 23E resembled that of
19Ey but urinary protein concentration was lower; 19E
showed only 1, 3, 4, and 7. (From Lauwerys et al., 1974)
-------
5-68
Number of
persons
50
40
30-
20-
10-
20 40
D
Normal pattern
Itai-itai pattern
60
Other pattern
80 100 age
FIGURE 5:3
The distribution of urinary protein patterns on
disc electrophoresis in relation to age among
inhabitants of the Itai-itai disease endemic
area. (From Shiroishi et al., 1972).
-------
5-69
Itai-itai endemic area
Control area
20 40 60 80
o
o
o
o
o
o
o o Oo 0
0°° ° O
o oo oo
20 40 60 80
years
FIGURE 5:4 Urinary cadmium excretion in relation to residence time
in area. Filled circles = Itai-itai patterns on disc
electrophoresis. (From Fukuyama et al., 1972).
-------
5-70
% prevalence of
urinary findings
Non-glutinous rice( 37villages)
40-
30-
20-
10-
n-
.
0 • *
" " t.
A
• A_ .' '
Xd^, X ^
J^QuI '*
0.5
1.0
1.5 fjg Cd/g rice
50-
40-
30
20
10 -
0
no
Glutinous rice (29 villages)
0
0.5
—i—
1.0
—i—
1.5
2.0 ug Cd/g rice
• Villages with high prevalence of Itai-itai disease.
" Villages with low prevalence of Itai-itai disease.
A Villages with no Itai-itai disease within the polluted area.
X villages outside polluted area.
FIGURE 5:5 Prevalence of concurrent proteinuria and glucosuria
among persons over 50 years of age within villages
in relation to cadmium concentration in rice in
villages with varying prevalences of Itai-itai disease,
(Redrawn from Fukushima et al., 1973).
-------
5-71
Albumin to RBP ratio
1U
103
io2
10
1
°'o
Normal - A
x Itai-ltai disease
Patient c
x Relative • «
x x Renal disease x
* A
A,A *
A • x
A A •
A • * . • .. '
A A* * • * 'o
%N r *° • ° ° o
• x *ift»?0
C^* °° o
oo o
o
01 0.1 1 10 10
RBP mg./l
FIGURE 5:6 Urinary RBP concentration and the ratio albumin/RBP
in normal and some proteinuric conditions. (From Kanai
et al., 1972).
-------
5-72
Co
mg
^400
+ 300
1-200
>100
-100
-200-
group I control
— ncd
* killed
FIGURE 5:7 Balance of calcium metabolism of rats given two kinds
• of diets (calcium deficient with and without added
cadmium). Data are given for individual rats. (From
Kobayashi, 1973).
-------
5-73
lower .scrum (.'.:
stimulates I'TII
Kidney tubular cell
:ulciivl(:<:vcl;tsi!
I'-'IfiO ( l-2.r)-hv(lroxylas(
SliinulaloK (,';i-absorption
ssggaaiaKfflffi^^
FIGURE 5:8 A schematic drawing of the pathways involved in
Vitamin D metabolism.
-------
5-74
%
80 -
60-
Af\
«HJ
20-
:.:->::- % resorption
•*•*•*
XN1 % malformed
rrpr
1
|7^
• • * •
i • • • i
• * • •
i * • • i
* • • •
^
V//////////A
_^m
Cd Cd Zn Cd+Zn Cd2mg/kg
2mg/kg 4mg/kg 2mg/kg 2mg/kg + Zn2mg/kg
of each, after 15min.
simult. to 6 hours
FIGURE 5:9 A comparison of the teratogenic and embryocidal
effects of cadmium, zinc, and cadmium-zinc on
embryonic development in the golden hamster. The
protection afforded by zinc against the teratogenic
activity of cadmium diminishes as the interval
between injections increases. (From Ferm and
Carpenter, 1968).
-------
R-l
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R-2
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R-3
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R-4
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R-5
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R-6
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R-7
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TECHNICAL REPORT DATA
(Please read Instructions on the reverse before completing)
1. REPORT NO.
EPA-650/2-75-049
3. RECIPIENT'S ACCESSION-NO.
4. TITLE AND SUBTITLE
CADMIUM IN THE ENVIRONMENT III
and Epidemiological Appraisal
- A Toxicological
5. REPORT DATE
June 1975
6. PERFORMING ORGANIZATION CODE
7. AUTHOR(S)
Lars Friberg, Tord Kjellstrom, Gunnar Nordberg,
and Magnus Piscator
8. PERFORMING ORGANIZATION REPORT NO.
9. PERFORMING ORGANIZATION NAME AND ADDRESS
The Karolinska Institute
Stackholm 60, Sweden
10. PROGRAM ELEMENT NO.
1AA001
11. CONTRACT/GRANT NO.
68-02-1210
12. SPONSORING AGENCY NAME AND ADDRESS
Environmental Protection Agency
Special Studies Staff, MERC
Research Triangle Park, N. C. 27711
13. TYPE OF REPORT AND PERIOD COVERED
Final
14. SPONSORING AGENCY CODE
15. SUPPLEMENTARY NOTES
CADMIUM IN THE ENVIRONMENT I, APTD-0681, PB 199-795
CADMIUM IN THE ENVIRONMENT, II EPA-R2-73-190, PB 221-198
16. ABSTRACT
This report is a review of the recent biomedical literature on cadmium..
The major part of the material covered is from 1973-74, but some earlier
work not contained in volumes I and II is included. The recent findings
are <: scussed in relation to previous work where this is appropriate.
17.
KEY WORDS AND DOCUMENT ANALYSIS
DESCRIPTORS
b.IDENTIFIERS/OPEN ENDED TERMS
COSATI Field/Group
13. DISTRIBUTION STATEMENT
RELEASE UNLIMITED
19. SECURITY CLASS (ThisReport)
Unclassified
21. NO. OF PAGES
218
20. SECURITY CLASS (This page)
Unclassified
22. PRICE
EPA Form 2220-1 (9-73)
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