PB-221 198
CADMIUM IN THE ENVIRONMENT, II
KAROLINSKA INSTITUTE
PREPARED FOR
ENVIRONMENTAL PROTECTION AGENCY
FEBRUARY 1973
Distributed By:
National Technical Information Service
U. S. DEPARTMENT OF COMMERCE
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TABLE OF CONTENTS
CHAPTER 1 INTRODUCTION .
CHAPTER 2 ANALYTICAL METHODS
2.1 ATOMIC ABSORPTION
2'.2 ELECTROMETRIC METHODS
2.3 X-RAY ANALYSIS '
2.4 CONCLUSIONS
Tables 2:1
Figures 2:1-2:2
CHAPTER 3 OCCURRENCE, POSSIBLE ROUTES OF EXPOSURE AND
DAILY INTAKE
3.1 OCCURRENCE AND POSSIBLE ROUTES OF EXPOSURE
3.1.1 Cadmium in air ,: .
3.1.2 Cadmium in water
\,3.1.3 Cadmium.in soil '
3.1.4; J Cadmium in food
3.1. 5', Cadmium in tobacco products
3.2 DAILY ."INTAKE OF CADMIUM
3.3 CONCLUSIONS
Tables 3:1-3:2
Figures 3:1
CHAPTER 4 .METABOLISM
4.1 UPTAKE AND ABSORPTION
4.1.1 Gastrointestinal absorption
4.1.1.1 In animals
4.1.1.2 In human beings
4.1.1.3 Conclusions
4.1.2 Placental transfer
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4.2 TRANSPORT, DISTRIBUTION AND EXCRETION OF CADMIUM IN
ANIMALS
4.2.1 Uptake to and clearance from blood
4.2.2 Tissue distribution and retention
4.2.3 Distributuion within organs '-
4.2.4 Excretion
4.2.4.1 Urinary excretion ;; .
4.2.4.2 E^xcretion via the alimentary tract
4.2.4.3 Other excretion routes
4.2.5 Biological half-time
4.2.6 Influence of other compounds on the metabolism of
cadmium
4.3 TRANSPORT, DISTRIBUTION AND EXCRETION OF CADMIUM IN
NORMAL AND EXPOSED HUMAN BEINGS
4.3.1 Transport and distribution in blood
4.3.2 In organs
4.3.3 Distribution in organs
4.3.4 Excretion
4.3.4.1 Urinary excretion
4.3.5 Total body burden and renal burden
4.3.6 Biological half-time .
Conclusion - '
"1.4 RELATIONSHIPS AMONG CONCENTRATIONS OF CADMIUM IN BLOOD,
URINE AND ORGANS '
4.4.1 Relationships between concentrations of cadmium in
blood and in organs
4.4.1.1Inanimals ; "
4.4.1.2 In human beings
4.4.2 Ralatipnships between concentrations of cadmium in
urine or feces and 'organ or blood concentrations
4.4.2.1 In animals -" -
4.4.2.2 In human beings - . .
4.4.3 Conclusion's : :
4.5 METALLOTHIONEIN : - v -
4.6 GENERAL CONCLUSIONS ON METABOLISM -
fd-
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4.6.1 In animals
4.6.2 In human beings
Tables 4:1-4:2 . ;
Figures 4:1-4:14
' . / '
CHAPTERS EFFECTS AND DOSE-RESPONSE RELATIONSHIPS
5.1 RENAL EFFECTS AI^D DOSE-RESPONSE RELATIONSHIPS
5.1.1 In human beings
5.1.2 In animals
5.1.3 Dose-response relationships
5.2 EFFECTS ON BONE
5.3 EFFECTS ON THE LIVER '
5.4 OTHER EFFECTS <-" \ . ;.
5.5 CONCLUSIONS
Tables 5 i1
CHAPTER 6 EPIDEMIOLOGICAL INVESTIGATIONS IN CADMIUM-
POLLUTED AREAS OF JAPAN
6.1 INTRODUCTION . :
6.2 METHODOLOGY
6.2.1 Method for selection of areas studied for cadmium-
poll ut ion
^6.2.2 Standard, methods for screening of cadmium-related
/' disease ."..'.' ' : . ' ; -
-6.2.3 Standard method for qualitative measurement of
..'.... -proteinuria (Ministry of Health and Welfare, 1971b)
." . x " . . ' .
6.2.4 .Comparisons of proteihuria methods
6.2.5 Methods for estimating daily intake
6.3 CADMIUM EXPOSURE AND MEDICAL.' EFFECTS IN. INDIVIDUAL AREAS
6.3.1: Fuchu in Toyama Prefecture
6.3.2 Tsushima in Nagasaki Prefecture
6.3.3 Ikund area of Hyogo Prefecture
6.3.4 Kakehashi area in Ishikawa Prefecture
6.3.5 Bandai area in Fukushima Prefecture
6.3.6 Anhaka area of Gumma Prefecture
,6. 3.7 Omuta area in Fu'kuoka., Prefecture .
6;3.8''..; Uguisuzawa iarea in Mlyagi ^Prefecture ']-
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6.4 DISCUSSION
Tables 6:1-6:13
, Figures 6:1-6:12
CHAPTER 7 THE CAUSE OF THE ITAI-ITAI DISEASE
References
II
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CHAPTER 1 INTRODUCTION
This report updates the earlier review on cadmium carried out
under a contract (No. CPA 70-30) between the US Environmental
Protection Agency and the Department of Environmental Hygiene
of the Karolinska Institute, Sweden. The earlier report,
-with modifications, has also been published as a monograph,
Friberg, L., Piscator, M., and Nordberg, G.: Cadmium in the
Environment, CRC Press, Cleveland, 1971 (in the following
referred to as CITE). The present report is a result of a
f'J-
continued collaboration (contract No'^ 68-02-0342) between
the two institutions and covers available information, pub-
lished as well as unpublished, up to and including 1972.
The project officer of the US Environmental Protection Agency
for this project has been Robert J.M. Morton, M.D.
Like the previous review, 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 re-
searchers, including a five-week visit there by one of us
(Tord Kjellstrb'm), it has been possible to obtain and evaluate
much data from Japan which would not be available otherwise.
Papers published in Japanese could be taken into account
as well since one of us (Tord Kjellstrom) speaks and reads
Japanese.
We express our gratitude to the Environmental Agency of Japan,
particularly Dr. Yoshimasa Yamamoto, Chief of the Section
of Environmental Health and Public Hazards, as well as to the
Prefectural Institutes of Hygiene and Departments of Public
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Hazards in Fukushima, Gumma, Hyogp., Nagasaki, and Toyama,
as well as the Japanese Association of Public Health. Valuable
information and assistance have been received from.several
independent researchers. .Kenzabu.ro Tsuchiya, M.D. Professor
of Preventive Medicine, and Public Health, School of Medicine,
Keid University, assisted us in planning and executing val-
i
uable visits in Japan.
We express o.ur thanks to Ms. Pame.la Bost.on,: B.A., for assistance
in editing the English of the report. ...
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CHAPTER 2 ANALYTICAL METHODS
In our previous review Cadmium in the Environment (CITE) it
was concluded that there are methods which are reliable for
the determination of small amounts of cadmium in biological
material. At the same time,, it was warned that several erroneous
results have been reported in the past because of interferences,
most noticeably the interference of salts, especially sodium
chloride, in atomic absorption spectrophotometry analyses which
failed to take these into account.
During the last years, further experience has resulted in a
large number of articles on methods of analysis of cadmium. Yet,
systematic studies on accuracy, precision and other important
parameters have seldom been performed. In addition to dithizone
methods, emission spectroscopy, neutron activation and atomic
absorption spectrophotometry, which were treated in CITE,
some new developments are flameless atomic absorption, electro-
metric methods (anodic stripping polarography, pulse polarography,
anodic stripping voltammetry). The newly developed X-ray analysis
after proton irradiation is also of interest. Information about
analytical methods can also be found in a recent monograph,
Cadmium, the Dissipated Element, by Fulkerson et al., 1973.
2.1 ATOMIC ABSORPTION
For the analysis of cadmium in whole blood, Mauser, Hinners and
Kent, 1972, have developed a technique whereby 0.5 ml blood is
added to a flame-purged tantalum sampling boat, dried in an
oven and ashed at low temperature. Analyses is then performed by
flaming the ash directly in an atomic absorption spectrophotometer
with a deutrium background corrector. The method was used for
twelve replicate analyses of a blood sample and gave an average
of 0.35 yg Cd/100 ml blood with a variation coefficient of 27%.
Recovery, estimated by adding 10 yg Cd/ml blood to another sample,
was reported to have been complete. The detection limit is given
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as 0.02 yg Cd/100 ml blood, based on a pura water standard solu-
tion of cadmium. The detection limit of cadmium in blood is not
known.
Lener and Bibr, 1972, made some methodological studies on atomic
absorption spectrophotometry. They used an air propane flame in-
stead of the conventional air acetylene flame and state that by
using the former system, cadmium can be analyzed in concentra-
tions from 0.06 ppm. The authors found that the coefficient of
variation was 3.8% at a concentration of 0.06 ppm. This was
based on 20 repeated measurements of cadmium in water solution.
When applied to food, 4 analyses of the same sample of parsley
gave the result of 0.088 ppm with a standard deviation of 0.077.
(In the article, the term "standard error" is used, but must
mean standard deviation). For a sample of carrot the coefficient
of variation for 5 analyses was about 30%.
For determination of cadmium in urine and blood, Vens and
Lauwerys, 1972, passed urine acidified with 1.5 N HC1 or hemo-
lyzed blood in 1.5 N HC1 through a basic resin, which binds
cadmium. Elution was performed with 2 N perchloric acid and
cadmium was then determined with conventional atomic absorption
spectrophotometry. The coefficient of variation was 10% at a
cadmium concentration of 1.5 yg/1. The accuracy is not known.
In 44 normal subjects the mean urinary concentration was 1.37
yg/1 (S.D. 1.38) or 0.95 yg/g creatinine (S.D..Q.72). In 24
normal subjects the mean concentration in blood was 0.95 yg/100
ml [S.D. 1.0), which is higher than earlier reported.
In CITE it was mentioned that extraction methods followed by
atomic absorption .analysis were reliable for the determination
of cadmium in urine. It was also stated.that good agreement was
obtained in Japan among different laboratories, for the same urines.
Similar interlaboratory studies have been performed in Japan on
rice samples (Yamagata et al., 1971). Ten laboratories participated
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using a standard method of analysis for determination of cadmium
in rice. Some of the steps are wet ashing with nitric acid
and sulfuric acid, extraction with APDC-MIBK and measurement by
atomic absorption. The means for two rice samples were 0.176
and 2.33 ppm and the ranges 0.14-0.20 and 2.20-2.75 ppm, respec-
tively., giving a coefficient of variation of about 10 percent
for both samples. Since it is difficult to obtain homogenous
rice samples, these results indicate a high degree of accuracy
in these Japanese laboratories. In one of the laboratories, a
.comparison was made between a method involving low temperature
ashing followed by extraction into acid and the above mentioned
standard method (chloroform used instead of MIBK). Eight deter-
minations on the same rice sample gave 0.188 (S.D. 0.005) and
0.189 (S.D. 0.014) ppm respectively.
The above mentioned results indicate that the Japanese data for
cadmium in rice can be regarded as generally very reliable,
which is of importance when discussing exposure (see Chapter
6).
For determination of cadmium in grains a method using flameless
atomic absorption has been developed by Kjellstrb'm et al. (to be
109
published). Radioactive Cd was added to 2-gram and 4-gram
samples of wheat. Radioactive analysis was compared with flameless
atomic absorption and conventional atomic absorption (with and
without extraction in PlIBK/APDC system). The deutrium lamp tech-
nique was used for background correction. The flameless atomic
absorption was performed in the following way. The sample
was dry ashed twice and the ash was dissolved in 1-M HMD
and 20 yl of this solution was injected into a Parkin-Elmer
HGA-70 heated graphite atomizer. This method showed a higher
repeatability than conventional atomic absorption and the
recovery (average 95%) was about 10% higher than for the
method using extraction. In Figure 2:1 is shown the result
of flameless atomic absorption analysis of cadmium. The accur-
acy of the new method for cadmium analysis was studied by
Linnman et al. (to be published), who compared it with
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neutron activation [method of Ljunggren st al., 1971). The
results are shown in Figure 2:2. A good correlation between
the methods is shown at cadmium concentrations in wheat
between 20 and 200 ng/g.
2.2 ELECTROMETRIC METHODS
Basically related to the classic polarographic method, these
methods have been improved to increase their sensitivity.
Anodic stripping voltammetry (ASV), which utilizes either
mercury electrodes or solid electrodes, has been used in
several investigations for the determination of cadmium and
other metals in water (Whitnack and Sasselli, 1969; Allen,
Matson and Nancy, 1970), in food (Hundley and Warren, 1970)
and in'blood serum (Sinko and Gomiscek).
The ASV-method was compared with another method only in thk
report involving the food samples (Hundley and Warren, 1970).
Here.it was compared with atomic absorption spectrophotometry,
but it was not stated how this latter method was performed.
There seems to have been a poor agreement between the two
methods and these data do not not help to assess the value of
the ASV-method. .
Pulse polarography was used by Abdullah and Royle, 1972, to
determine cadmium in sea water after pre-concentration of metals
on resins. Only one value is given for cadmium in sea water,
1.38 yg/1 and this method cannot be evaluated at present.
2.3 X-RAY ANALYSIS
Johansson, Akselsson and Johansson, 1970, showed that it is
possible to detect small amounts of elemen'ts by observation
of characteristic X-rays after proton bombardment. Since this
method is non-destructive, repeated analysis can be made on
the same sample. As yet, the problem of quantitative deter-1
mination of small amounts of cadmium in biological fluids
has not been solved, but in the future, this method may be
of great value for cadmium analysis.
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2.4 CONCLUSIONS
A number of potentially very useful methods for analyses
of even very low concentrations of cadmium in biological
material are now available. To date, few strict methodological
studies on accuracy and other important parameters have been
carried out. This is a severe limitation, as witnessed by
some recent reports on occurrence and metabolism of cadmium
in which serious analytical errors must have been involved.
It is therefore necessary to evaluate the analytical methods
used before accepting data.
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TABLE 2:1 Cadmium content in some foods (yg/g wet weight).
(From Lener and Bibr. 1972).
Sample
Celery
Parsley
Garlic
Carrot
Qnion
Potatoes
Milk
Egg yolk
Egg white
No. of
Analyses
5
4
5
5
5
5
5
4
4
Direct
M
0.058
0.088
0.077
0.086
0.047
0.092
0.010
0.120
0.076
measurement
S.E.
0.013
0.077
0.001
0.024
0.003
0.002
0.003
0.005
0.004
Measurement after
extraction
M S.E.
0.059
0.086
0.075
0.069
0.046
0.090
0.012
0.121
0.073
0.011
0.006
0.001
0.016
0.002
0.002
0.003
0.004
0.005
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Total Cd(ngyg)found
resp.
wet weight
\
140
120
100
80-
60
40
20
;. J
o o
fr
6>
Cd 2g samples ppb
OCd4g
Zn 2g samples ppm
a Zn 4g -
* "9/9
H) 20 30 40 50 60 70 80 wetweight
Cd added (huxrited wi
Zinc was analyzed with conventional atomic absorption (AAS-F)
in order to show that all samples were identical in respect to
original metal content.
FIGURE 2:1 Result of flamaless atomic absorption cadmium
analysis of two different sizes of wheat samples
to which cadmium (labelled with 109Cd) had been
added. (From Kjellstr&m et al., to be published).
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7-o
Atomic
absorption
300
200-
lOOi
n» 59
r > 0.946
y = 1.0U - 1.65
too
200 300
Activation analysis
«9/9
FIGURE 2:2 Result of analysis of cadmium in wheat using
flameless atomic absorption method and neutron
activation method. (From Linnman et al.. to be
published).
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CHAPTER 3 OCCURRENCE, POSSIBLE ROUTES OF EXPOSURE AND DAILY INTAKfcl
3.1 OCCURRENCE AND POSSIBLE ROUTES OF EXPOSURE
3.1.1 Cadmium in air
In the previous review (CITE) it was concluded that "normal" con-
3
csntrations of cadmium in ambient air are 0.001 yg/m or less
in rural areas. In cities mean yearly concentrations of up to
0.05 yg/m may be found, and in areas near cadmium emitting in-
dustries weekly means of 0.3 yg/m have been recorded.
The values reported have been verified during the last years.
Just and Kelus, 1971, found mean yearly concentrations of cadmium
3
in air from 0.002-0.05 yg/m in 10 Polish towns. Creason et al.,
1972, found at 4 sites in Cincinnati, Ohio, cadmium concentrations
3
in air from 0.0001-0.04 yg/m (means for 3-5 days). The concen-
trations were about the same at 25 and 100 feet from the roadway
indicating that traffic did not influence cadmium concentrations
in air.
In the Chicago area Harrison and Winchester, 1971, during 6
24-hour sampling periods from Nay to August at 50 sampling
stations recorded cadmium concentrations in air from less than
0.005 Pg/m3 to 0.08 yg/m3. Severs and Chambers, 1972, found
3
24-hour values during one day of up to 0.33 yg/m in Houston,
Texas. In the city of East Helena, Montana, the average concen-
tration during a three-month sampling period was 0.06 and
3 '
0.29 yg/m at about 1300 and 800 meters respectively from a smel-
ter (Huey, 1972). The maximum 24-hour value was 0.7 ug/m
(U.S. Environmental Protection Agency, 1972).
Nagata et al., 1972, report on cadmium concentrations in am-
bient air in Tokyo during 1969 to 1971. Mean values over sev-
eral months in different areas varied from 0.010 to 0.053 with
a
a maximum 24-hour value of 0.53 yg/m .
The deposition of airborne cadmium has been further studied in
Scandinavia (at about 100 different places) by analyses of cad-
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miurn concentrations in moss. As seen in Figure 3:1 there is an
obvious difference between the southern and the northern parts
of Sweden, Norway and Finland (Ruhling and Tyler, 1972). Floss
analysis has also been used in Great Britain by Goodman and
Roberts, 1971, and Burkitt, Lester and Nickless, '1972, to study
the distribution of cadmium pollution. The latter authors found
about 50 ppm of cadmium in moss at distances of 6 miles from a
smelter. This confirms that considerable air pollution of cadmium
may spread to relatively long distances from emission sources.
Secular trends in cadmium deposition have been studied by com-
paring cadmium concentration measured in moss saved from several
decades ago with that in moss from present times. The old samples
consisted of moss from the years 1927-1942 (herbaria samples)
from 10 sites in the rural areas around the city of Uppsala,
Sweden, and moss from 3 sampling sites in the city of Uppsala,
collected in 1916-1917.
It was found that in the rural areas around Uppsala there had
been a mean increase from 0.2 to 0.3 ppm in moss during the
intervening 20-30 years. In the city a mean increase from 0.2
to 0.4 ppm was observed during a 50-year period (Gelting and
Ponten, 1971). The increase was consistent in several compari-
sons . . . .
In a rural, subarctic area in Finland, Laamanen, 1972, found
2
a deposition of cadmium from less than 0.001 mg/m /month (winter)
to 0.006 mg/m /month (summer) by measuring cadmium in dust fall.
These data may be compared with similar studies in the city of
2
East Helena in Montana, where values of 1-4 mg/m /month were
found up to about 1,000 meters from a cadmium emitting smelter
(Huey, 1972). These latter data are comparable to those presented
in CITE for an area near a Swedish industry (0.4-40 mg/m /month).
The relationship between dust fall of cadmium and concentrations
of cadmium in air has been studied by Pinkerton et al., 1972.
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Thay found that dust fall values of 0.055 and 0.091 mg/m /month
corresponded to concentrations of cadmium in the air of'0.0032
a 3 .
Ug/m and 0.0048 yg/m respectively. It was also found that in
an area with a monthly dust fall of cadmium from 0 to 0.12
mg/m /month household dust contained between. 4.25 and 1.2.5 ug
Cd/g dust. Corresponding values in an area where the dust fall
was from 0.04 to 0.22 mg/m /month were 8.75'to 14 yg/g dust.
3.1.2 Cadmium in water
In the previous review it was concluded that in areas not
known to be polluted by cadmium, the concentrations of cadmium
in watar generally are less than 1 ppb, both in natural waters
and in drinking water. ' '
In two recent papers from Great Britain, cadmium has been de-
termined in sea water, both on and off coast. Preston et'al.,
1972, found a geometric mean of 0.04 ppb in 21 samples of fil-
trated sea water collected in the Irish .Sea, whereas near the
coast, in the Liverpool Bay, in 9 samples, a geometric mean of
0.41 ppb water was obtained. This latter value is in good agree-
ment with data by Abdullah, Royle and Morris, 1972, who found
a mean value in the Liverpool Bay of 0.27 ppb. According to
Preston et al., 1972, the highest concentrations in the coastal
waters around Britain were found in the North Sea, where the
mean was 0.41 ppb.
In drinking water, a WHO working group (World Health Organi-
zation, 1972) recommended that cadmium concentrations should not
exceed 5 ppb.
3.1.3 Cadmium in soil
In CITE it was concluded that.in non-polluted areas cadmium
concentrations in soil generally are below 1 ppm, whereas in.
areas near cadmium emitting industries, considerably higher
values may be found. It was stated that information is lacking
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on what factors determine the uptake of cadmium by plants, and
on the extent to which selective mechanisms operate. It was
also pointed out that the use of sewage sludges as fertilizers
might increase cadmium concentrations in soil.
OdSn, Berggren and Engvall, 1970, determined cadmium in sewage
sludge from 56 plants in the southern and middle parts of Sweden.
The median concentration of cadmium was 12 ppm dry weight (range:
2-61 ppm). Borrow and Webber, 1972, have reported on metals in
sewage sludge from 42 sewage works, scattered throughout England
and Wales. The samples were collected in 1964. Of these 42 samples,
7 contained more than 100 ppm dry weight.
The cadmium uptake in radish and lettuce was studied by John,
Van Laerhoven and Chuah, 1972. Cadmium chloride was added to
thirty different soil samples in pots [original cadmium concen-
trations not given) to give a concentration of 100 ppm,
and corresponding samples without added cadmium were used
as controls. After a growing period of 3 weeks, a reduced
yield of both radish and lettuce was found. Cadmium was deter-
mined by atomic absorption with correction for background
absorption and light scattering. Cadmium concentrations on
a dry weight basis in radish roots were on an average 387
and 7.4 ppm respectively, and in lettuce tops 138 and 2.3
ppm respectively.
The concentrations reported in the control plants are high.
There is no doubt, however, that cadmium concentrations in
these two foodstuffs greatly increased when grown on cadmium
contaminated soil. It was also shown that the uptake was
related to pH, i.e. increased soil acidity resulted in
higher cadmium concentrations in plants.
Linnman et al. (to be published) studied the uptake of cadmium
in wheat grown in test pots at different sewage sludge additions
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(corresponding to 0 up to 175 tons/hectare) and different
pH levels. All samples were analyzed for cadmium both by
means of flameless atomic absorption with background correc-
tion and by neutron activation (for a comparison of the methods
see Chapter 2, Figure 2:2). '
The results of the studies can be seen in Table 3:1 where.
cadmium uptake in wheat in relation to added sewage sludge,
cadmium concentration in soil and pH of soil is given. It
is seen that a considerable cadmium uptake occurs in wheat
when sewage sludge is used as a plant nutrient source. The
lower the pH the greater was the cadmium concentration in .
wheat. It should be mentioned that the two lower levels of
added sludge, 6.5 and 19 ton/hectare are in agreement with
Swedish recommendations for annual applications (Linnman
et al., to be published). These results are from laboratory
studies and field studies are now needed.
3.1.4 Cadmium in food
In CITE it was concluded that most foodstuffs contain less
than 0.05 ppm cadmium wet'weight. Liver, kidney and some
marine organisms, such as shellfish, may contain much higher
quantities of cadmium, even in non-polluted areas. Rice
and wheat, two important foodstuffs, may accumulate cadmium
to concentrations of more than 1 ppm in polluted areas. Con-
siderable difficulties in the analysis of the often very
low concentrations of cadmium in foodstuffs were acknowledged
and some results'were regarded as unreliable.
Co.rneliussen, 197.0, and Corne.liussen '(in .press) report on an
extensive study of cadmium content in different types of
food. The .samples were collected from 1966 to 1970, from
30 markets in 24 different cities in the United States. Cad-
mium was analyzed by atomic absorption and/or polarography
at a sensitivity of 0.01 ppm. The results have been compiled
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in Table 3:2. In most food categories the mean cadmium con-
centration was less than 0.05 ppm and the maximum concentra-
tion below 0.1 ppm.
Zook, Greene and Morris, 1970, determined cadmium in different
kinds of wheat, commercially prepared flours from these wheats
and products prepared from the flours. With the method used
(atomic absorption with background correction) mean cadmium
concentrations in wheat varied from 0.07 to 0.13 ppm (dry weight).
Corresponding flours had cadmium concentrations from 0.05 to
0.10 ppm. Cadmium concentrations in 10 consumer products based
on wheat were from 0.03 to 0.22 ppm dry weight. Corrections
to wet weight would probably lower the values by about 10
percent. The values given may be somewhat high. When the
atomic absorption method was compared with the conventional
dithizone method, the latter showed values about 40 percent lower.
There have been several investigations of the cadmium content
in fish. By analysis of 19 whole fishes from the Great Lakes,
Lucas, Edgington and Colby, 1970, found an average cadmium
concentration of 0.094 ppm wet weight (neutron activation ana-
lysis). Analysis of livers from 10 different species of fish
showed mean values from 0.06 to 1.4 ppm wet weight. In an ex-
tensive study from New York State, Lovett et al., 1972 exa-
mined 406 fishes from 49 freshwaters by atomic absorption tech-
nique. The majority of samples of fish meat contained 0.02
ppm or less, and only in a few cases were concentrations
above 0.1 ppm found. In the trout> for instance, there was
no relationship between age and cadmium concentrations. Havre,
Underdal and Christiansen, 1972, determined cadmium in meat
of fish from a Norwegian fjord, thought to be polluted by
cadmium. Analyses were performed by atomic absorption spec-
trophotometry after extraction in an organic solvent. Cadmium
concentrations in 21 samples of cod ranged from 0.001-0.041
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ppm, in 5 samples of pollack from 0.002-0.006 ppm and 14
samples of flounder from 0.005-0.024 ppm wet weight. In 10
cods, cadmium in liver ranged from 0.109-2.225 ppm wet
weight. In short, these three investigations on fish show
that cadmium concentrations in fish meat usually are very
low, whereas in internal organs considerably higher concen-
trations may be found.
Taylor, 1971, reports on cadmium concentrations in samples of '
fish and fish products from Great Britain. Although,the results
are difficult to 'interpret because the analytical method is not
mentioned, the following data are given- Cadmium concentrations
in 48 samples of tuna fish were.all below 0.2 ppm, but some
salmon meat was reported to .contain more than 3 ppm. The highest
concentrations, up to 5.3 ppm, were found in fish paste.
Reynolds and Reynolds, 1971, examined the cadmium content of
crabs (dithizone method).. Cadmium concentrations in the white
meat were relatively, low, 0.02-1".! ppm, while dark, body meat con-
tained from 2.5 to 8.6 ppm of cadmium wet weight.
The cadmium content of German wine was investigated by Eschnauer,
1965, (polarographic method), who found a mean of 3.1 ppb
(1.3-4.1) in 13 wines. Bergner, Lang and Ackermann, 1972,
(atomic absorption after extraction in organic solvent) found
a mean cadmium concentration of 2.9 ppb (0.5-8) in 22 wines
and 71. and 40 ppb, respectively, in 2 wines from 1965. Essing
et al., 1969, (atomic absorption after extraction in organic
solvent) found means of 17 and 8 ppb in 4 red wines and 4 white
wines respectively.
3.1.5 Cadmium in tobacco products . ;
In CITE it was mentioned that cigarettes may contain 1-2 ppm
of cadmium, and that part of the cadmium could be released into
the mainstream and inhaled. Further data supporting cigarettes
-------
-15-
as an important exposure source have been given by Menden
et al., 1972. In. American cigarettes they found amounts
of 1.56-1.96 yg/cigarette (atomic absorption spectrophoto-
metry). By use of a smoking apparatus (35 mi-puff, 2 seconds
every minute) it was found that the particulate phase of
the mainstream contained 0.10-0.12 yg/cigaretta. For a smoker
of 20 cigarettes daily, this means an inhalation of about
2 ug cadmium per day.
Confusing results have been reported by Tomita, 1972, who
studied 12 different Japanese brands with a smoking machine.
Instead of measuring the amount of cadmium in the mainstream,
he mentions that he collected and analyzed cadmium in
the sidestream in three bottles. He also measured the
amount of cadmium in the whole cigarette, butt and ash.
Through subtraction he got the amount in the mainstream.
Tomita states that between 30-50 percent of the cadmium
in the cigarette may be inhaled by .the smoker, which is
a figure far above other reported data. The possibilities
for serious methodological errors are obvious. The data
on the amount of cadmium in whole cigarettes are between
1.35 and 2.5 yg, in accord with data from other countries.
Cadmium.content in snuff has been determined (Baumslag, Keen
and Petering, 1971). American snuff contained 0.7-0.9 ppm
of cadmium and snuff used in South Africa contained 1.1-1.5
ppm of cadmium. This latter type of snuff is a mixture of pow-
dered tobacco with ash of incinerated plants and herbs. The
method used was atomic absorption.
3.2 DAILY INTAKE OF CADMIUM
In CITE it was concluded that the daily intake in uncontaminated^
areas is about 50 yg. This estimate was based on data from
-------
-16-
some countries in Europe, the United States and Japan. This
value may be compared with a tolerable weekly intake of
400-500 yg, i.e. about. 70 yg/day, proposed recently by a
joint FAQ/WHO expert committee on food additives (World
Health Organization, 1972).
Fukushima, 1972, has calculated that in a non-polluted area
of Japan the average daily intake would be 47 yg. Concerning
daily intake in polluted areas of Japan, see sections 6.2.5
and 6.3.
in CITE daily intake was discussed based on only data on cadmium
concentrations in food and raw material, it is'possible to
use another approach. The amount of cadmium excreted in feces -
would consist of unabs.orbed ingested cadmium to 90-95 percent,
meaning that the fecal excretion would correspond' approximately
to the daily intake of cadmium.
In CITE it was reported that in one study in West Germany covering
23 persons Essing et al., 1969, estimated the daily fecal excretion
to be 31 yg. Tipton and Stewart, 1970, in a long-term balance
study of 3 American men found .a mean fecal amount of.42 yg
Cd/day. Tsuchiya, 1969, referred to Japanese data from a
non-contaminated area showing an average daily amount of 57
yg in feces from 4 men. These data for the1 most part confirm
the figure of 50 yg given above for the daily intake. There
is a tendency for.a somewhat higher value in Japan and a
somewhat lower one in Germany.
Unfortunately no methodological studies on cadmium analysis
in feces have been reported. There is reason to believe that
feces analyses are rather reliable even without extraction
methods si:nce interfering salts are'not;'p':resent to the same
extent as in urine.
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-17-
3.3 CONCLUSIONS
Cadmium concentrations in ambient air vary from less than
3
0.001 yg/m in non-polluted areas to several tenths of a
microgram in areas near cadmium emitting industries. Moss
analyses have indicated that in one part of Sweden dust
fall of cadmium has increased during the last 50 years.
Cadmium concentrations in both natural and drinking water are
usually less than 1 ppb. The uptake of cadmium in grains,
such as wheat, is influenced by the pH and the cadmium con-
centration of the soil. The use of sludge may increase the
cadmium uptake in wheat grains severalfold. The available
data on wheat are from laboratory studies and field studies
are needed.
Analyses of cadmium in foodstuffs have shown that cadmium
concentrations generally are less than 0.05 ppm. In marine
organisms, fish meat contains very small amounts of cadmium,
whereas internal organs of fish and shellfish contain appre-
ciable amounts.
The previous estimate of a daily intake of 50 yg cadmium
in non-polluted areas still seems to be the best average
estimate, granted a possible regional variation from 30-
70 yg.
-------
TABLE 3:1 Cadmium uptake in wheat in relation to added sewage sludge,
cadmium concentration in soil and pH of soil. Means of four
replicates. Atomic absorption, ppb dry weight. (From
Linnman et al., to be published).
Sludge
ton/ha
0
6.5
19
58
"175
CaO
added (%)
Added
Cadmium in soil
ppm
0
0
0
0
0
.031 :
.094
.28
.84
0
phi
4.8
4.8
5.1
5.3
5.8
Cadmium
uptake
ppb
67
119
170
257
124
0.1
pH
6.1
6.1
6.2
6.2
5.9
Cadmium
uptake
45
86 :
123
134 :
147
0.2
pH
7.4
7.2
7.2
6.8
6.5
Cadmium
uptake
ppb
29
33
50
86
122
-------
TABLE 3:2 Cadmium content ppm wet weight in different food categories
in USA. Total number of samples: 30. (From Corneliussen,
1970; Corneliussen, in press).
Cadmium ppm wet weight
Type of food
Dairy products
Meat, fish and
poultry
Grain and cereal
products
Leafy vegetables
Legume vegetables
Root vegetables
Garden fruits
Fruits
Oils, fats and
shortening
Sugar and adjuncts
Beverages
Potatoes
1968-1969
No. >0.01
10
21
27
27
16
24
25
15
27
18
8
-
Maximum
0.09
0.06
0.08
0.08
0.03
0.08
0.07
0.38
0.13
0.07
0.04
-
1969-1970
No. >0.01
9
22
27
28
10
27
27
10
28
27
9
29
Maximum
0.01
0.03
0.06
0.14
0.04
0.06
0.07
0.07
0.04
0.04
0.04
0.08
-------
MU-O.I25-0.25-OSO-0.75-1.00-IV)
» M !»* *»* - t.**»,».W I
«. ^iff - .. !
*'V-\- . .**"*.._." !
FIGURE 3:1 Isocurvos for cadmium (ppm dry woight) in
moss in different parts of Scandinavia.
Broken lines - values uncertain.
(From Ruhling and Tyler. 197?).
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-18-
CHAPTER 4 METABOLISM
At a recent international symposium on accumulation of
toxic metals (Task Group on Metal Accumulation, 1973) gene-
ral aspects on absorption, transport, distribution, excre-
tion and accumulation of metals were discussed.
The term "absorption" was defined as "entry into the body
by passage of the metal compound across a membrane". Accord-
ing to this definition, e.g. metal taken into the cells of
the mucous lining of the gastrointestinal tract should be
considered as absorbed metal, even if the metal passes again
out into the gastrointestinal lumen and out with feces,
without ever reaching the circulation. The term "systemic
absorption" was never used. The term "absorption" in the
following text will me'an the amount or fraction of metal
entering the circulation (i.e. systemic absorption).
The amount of metal found in feces derives from the fraction
of ingested material, that passes unabsorbed through the
gastrointestinal tract as well as from net gastrointestinal
excretion. Net gastrointestinal excretion rs defined as
total gastrointestinal excretion minus the amount of metal
reabsorbed. Gastrointestinal excretion in this context
also includes possible excretion by glands in the upper
parts of the alimentary tract.
In the following the terms defined above concerning various
types of gastrointestinal absorption and excretion will be
used.
t
4.1 UPTAKE AND ABSORPTION
In our previous review (Cadmium in the Environment, = CITE)
it was concluded that cadmium is absorbed to a considerable
degree after inhalation. Absorption is primarily from the
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-19-
lungs, but to some extant also from the gastrointestinal
tract after mucociliary clearance. Human data on absorption
were not available but animal experiments suggested an absorp-
tion of between 10-40 percent of inhaled cadmium. Results
from new studies are not available and it is therefore impos-
sible to give any further data on the fate of inhaled cadmium.
Further proof that smoking will .cause inhalation 'and absorption
of cadmium will be given in section 4.3.5.
With regard to gastrointestinal absorption, animal experi-
/
ments indicated that a few percent of orally administered
cadmium was absorbed and studies on one human being indi-
cated an absorption of about 6 percent of ingested cadmium.
Furthermore it was shown that dietary factors influenced
the absorption of cadmium. Especially a low intake of cal-
cium resulting in calcium deficiency would .increase this
uptake.
4.1.1 Gastrointestinal absorption
4.1.1.1 n
The absorption of orally administered cadmium (1.7 and
0.17 mg Cd/kg body weight) in four monkeys was reported
in CITE. The retention 10 days after exposure was 2.5 to
3.2 percent. Two additional monkeys exposed to a single dose
of only 1 yg/kg body weight have now been studied (Nordberg,
unpublished data) .The retention after 10 days was of the
same magnitude, 2 and 3 percent. This retention is considerably
lower than the one reported by Suzuki et al., 1971, only
5 days after -a similar exposure in a monkey. They found about
20 percent of the dose in the gastrointestinal tract at that
time. These results may indicate that a considerable amount
of unabsorbed cadmium will pass out via fetpes as late as
between the 5th and the 10th day.
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-20-
Ogawa et al., 1972a, gave mice a single oral dose of 1 yCi of
mCdd2. The whole body retention after 24 and 48 hours
was 7.3 and 2.7 percent respectively. As gut contents will
be included in these figures, it can only be concluded that
the retention was less than 2.7 percent after 48 hours, which
agrees with earlier data on mice. Differences in retention
rates after oral exposure to cadmium sulfate and cadmium
stearate were found by Schmidt and Gohlke, 1971. They gave
rats by stomach tube 15 mg Cd/kg of body weight of the
compounds twice a week for 7 weeks. It can be concluded that
cadmium levels in liver after 3,7 and 1.6 weeks in rats
which had received cadmium stearate were only 44, 32 and
51 percent respectively of the levels found in animals
given cadmium as sulfate.
In two investigations the influence of calcium deficiency on
absorption and retention of cadmium after oral exposure has
been described. Kobayashi, Nakahara and Hasegawa, 1971, gave
rice containing about 0.1 and about 0.6 ppm of cadmium to
mice on low and normal calcium intake. After 70 weeks
of exposure, it can be seen that animals on a low calcium
diet had liver and kidney concentrations of cadmium 50
percent (mice exposed to 0.1 ppm Cd) to 300-400 percent
(0.6 ppm) higher than mice on a normal calcium diet. Piscator
and Larsson, 1972, gave rats on low and normal calcium
diets cadmium in drinking water in concentrations ranging
from 0-10 ppm for 1 year. Calcium deficient animals retained
about twice as much cadmium in liver and kidney as those
on a normal calcium diet. These two reports give further
support that calcium deficiency will increase the absorption
of cadmium.
4.1.1.2 _In_hjjman
Rahola, Aaran and
given orally to 5 human male volunteers, age 19-50 years. They
Rahola, Aaran and Miettinen, 1971, studied the fate of 115mCd
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-21-
receivsd single doses of 4.8 - 6.1 uCi of mCd, mixed with
a calf kidney suspension. The total ingestion of cadmium was
about 100 pg. During the first 3-5 days after administration
about 70 percent of.the activity was eliminated, primarily in
the feces. A rapid elimination continued until about 6
percent (4.7 - 7.0 percent) of the dose remained in the
body. This indicates an average absorption of at least
6 percent.
Kitamura, 1972, reported on two balance studies performed oh
a 55-year old man. In one study 5 mg of C'd (NO.,)- was admin-
istered in drinking water (10 ppm Cd) during one day. The total
fecal amount was collected during 15 days and cadmium excretion
thus calculated. During the first six days, Kitamura analyzed
cadmium concentrations in urine, which varied between 5 and
17 yg/1. Before the experiment he had found 16.1 yg/1 and
therefore concluded that urinary cadmium excretion did not
play any significant role in the elimination of absorbed cad-
mium after a single exposure. The absorption of cadmium was
calculated as the amount given minus the accumulated amount
excreted in feces. In-order to establish a background fecal
excretion of cadmium, the subject ate rice containing a
total of 20 yg cadmium per day from the day before the
experiment and for 6 days. Apart from this rice, the subject
'a'te an unidentified amount of other food with low cadmium
content (Kitamura, pers. comm.). In this way Kitamura estimated
the background excretion to be 20 yg and subtracted this
from the measured values. Between the 6th day and the 15th
day the subject ate common food. Kitamura calculated that
the long-term absdrption of this single dose in drinking
water would be 5.34%.
In another experiment, Kit.amura, 1972, administered about 5 mg
of Cd(NO_)_ in rice to the same person. The experiment was
-------
-22-
psrformad in a similar way but no background measurements were
made and no urinary excretions evaluated. Using the same back-
ground (20 yg/day) a long-term absorption of 1.35% was calcu-
lated. Based on Kitamura's data, it can be calculated that,
if the fecal background excretion instead had been 40 yg/day,
which better corresponds to reported cadmium-intakes in
Japan (section 6.2.5), absorption would be about 10%. A
doubling of the background gives a sevenfold increase in
absorptionl A possible error in background is multiplied
into larger errors in calculated absorption, when the method
by Kitamura is employed.
Alexander, Delves and Clayton, 1972, made balance studies
on children. There must have been serious errors in
the analytical procedures because they found a mean urinary
excretion far above what is seen even in exposed workers.
The data cannot be used for an evaluation of absorption
of cadmium. .............
4.1.1.3 _
New data have confirmed earlier observations both with regard
to absorption in animals and in human beings. In male
adult human beings the absorption rate is about 6 percent.
When there is a great calcium demand or a calcium deficiency,
absorption may be considerably higher. In CITE, it was stated
that an absorption in humans of about 10 percent of ingested
cadmium must be considered quite possible in the individual
case. In view of the new data this figure may be even higher.
4.1.2. Placenta! transfer
Tanaka et al. , 1972, gave pregnant mice single intravenous
injections of 50 yCi of Cd as chloride (about 15 yg Cd/
mouse) 24-36 hours before delivery. The mean uptake in new-
borns was 0.09 percent of the dose.
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-23-
4.2 TRANSPORT, DISTRIBUTION AND EXCRETION OF CADMIUM IN ANIMALS
4.2.1 Uptake to and clearance from blood
It was concluded in CITE that cadmium in blood after injection
will initially be found mainly in plasma. During the first
24 hours there is a rapid decrease in plasma. After about
24 hours the cadmium content in the red cells increases.
It was also concluded that metallothionein plays a role in
the transport of cadmium in the red cells.
New data give further proof for the above mentioned cadmium
metabolism in blood. Shaikh and Lucis, 1972a, gave rats sub-
ing
cutaneous injections of 2.2 yg Cd as the chloride. There
was a rapid initial decrease in plasma levels of cadmium
24 hours after injection and an increase in the red'cell
levels. Cadmium in plasma was associated predominantly with
3-globulins. Nordberg, 1972a, gave mice single subcutaneous
109
injections of Cd as the chloride corresponding to 1 mg
Cd/kg body weight. Cadmium concentrations in cells and plasma
were studied from 20 minutes to 96 hours after injection..
Figure 4:1 shows an initial uptake in the red cells with
a first maximum reached after about 4 hours. There was then
a decrease in the cadmium content in the red cells up to
24 hours, and then once again an increase. After 96 hours
the concentration was more than twice as high as after
24 hours. In plasma there was a rapid decrease from 20 minutes
to 48 hours. After that there was an increase in plasma levels.
Nordberg also studied the distribution of cadmium in the
red cells by separating hemolysates on G-75 Sephadex columns.
After 20 minutes most of the cadmium was in high molecular
weight fractions whereas only a minor part was in the fraction
corresponding to hemoglobin and an insignificant amount
in the fraction corresponding to metallothionein. After.
96.hours a redistribution had taken place,' so that about
1/3 of the total cadmium was found in fractions corresponding
-------
-24-
to mstallothionein. The main part was still in high molecu-
lar weight fractions, and no cadmium was observed in the
hemoglobin peak. In plasma, at 20 minutes and 4 hours after
injection, the main part of the cadmium was in fractions
corresponding to albumin or larger proteins.
4.2.2 Tissue distribution and retention
In CITE it was concluded that cadmium accumulates mainly in
liver and kidneys. After a single exposure the main part
of the cadmium is found in the liver. With time there will
be a redistribution and eventually the highest concentration
will be found in the kidneys, especially the cortex. When
a single exposure is involved, this redistribution eventually
will also cause the cadmium concentration in the pancreas
to exceed that in the liver. Before toxic effects, such
as renal tubular dysfunction, have occurred repeated exposure
will cause a continuous accumulation in organs. Once renal
damage has occurred, urinary excretion is increased. This
may lead to a decrease in kidney levels.
Shaikh and Lucis, 1972a, gave mice and rats single subcutane-
109
ous injections of 1.1 and 2.2 yg Cd as chloride respec-
tively. There was a continuous accumulation of cadmium in
mouse kidneys during the .observation period of 25 days,
whereas in the rat kidney accumulation ceased after 10 hours
after which renal levels of cadmium decreased. This was ex-
plained as a species difference, but the results in rats are
in sharp contrast to the results obtained by Gunn and
Gould, 1957. They found an increase in renal cadmium lev-
els continuing for months after a single injection in rats.
The drop in renal levels after 10 hours is also the opposite
from the earlier results obtained in rats by Lucis, Lynk
and Lucis, 1969.
-------
-25-
Suzuki at al., 1971, gave pregnant as well as non-pregnant
109
mice single subcutaneous injections of Q.OQ25 yCi Cd as
chloride (specific activity not stated) per g body weight.
The pregnant rats tended to have higher amounts of cadmium
in kidneys and liver, whereas concentrations in digestive
tract and bones tended to be less than in controls. The
authors concluded that pregnancy may alter the metabolism of
cadmium.
The metabolic changes after repeated exposure have been
studied by Nordberg (unpublished data). The experimental
conditions have been described in detail (Nordberg and
Piscator, 1972). In Table 4:1 are shown organ concentrations
of cadmium in groups of mice exposed to 0.25 mg and 0.5 mg
Cd/kg body weight subcutaneously for 6 months. In the group
with highest exposure, signs of renal tubular dysfunction,
as indicated by tubular proteinuria, and a.sharp increase
in the excretion of cadmium had become evident 3 weeks be-
fore the end of the experiment. It will be seen that in the
spleen the cadmium concentration is twice as high in the
high exposure group as in the group with lower exposure.
This was also the case with other organs, such as- intestines,
testis, eye etc. Pancreas concentrations are about 50 percent
higher in the high exposure group. In contrast,, liver and
renal levels of cadmium are about the same in both groups.
Nordberg .(unpublished data) studied the relation between
cadmium in kidney cortex and whole kidney in mice given
109
Cd subcutaneously 5 days a week for 3-6 months.'In 6
mice given 0.5 mg Cd/day the ratio cortex/whole kidney
varied between 1.1 and 1.3. In 5 mice given 0.25 mg Cd/day
the ratio varied between 1.0-1.48. A mean ratio in 8 mice
exposed for 6 months to 0.025 mg Cd/day was 1.43 (range:
V
1.1-1.7). The ratios found in mice agree fairly well with
ratios found in human beings.
-------
Note that the page Nos 27 and 28 are
erroneously omitted and the text
continuous on page 29
-26-
The results by Nordberg in Table 4:1 also confirm earlier
results by Friberg, 1952, and Bonnell, Ross and King, 1960,
who found that during continuous exposure an accumulation
of cadmium in pancreas continued after accumulation in liver.
and kidneys had stopped.
The tissue distribution after long-term oral exposure has
baen studied by Stowe, Wilson and Goyer, 1972. Rabbits ware
given 160 ppm as the chloride in drinking water for 6 months.
The mean exposure was 15.5 mg Cd/kg body weight per day.
Mean cadmium concentrations in liver, kidney, pancreas and
spleen were 188, 170, 29 and 10 ppm wet weight respectively.
Histopathological examination revealed slight renal tubular
damage. The concentrations in kidney and spleen are similar
to those found in the above mentioned mice exposed to 0,25
mg/kg by injections, whereas the injection route resulted
in higher concentrations in the liver and much higher in
the pancreas.
The differences in accumulation rates of liver and pan-
creas will be of importance when discussing the findings
in human beings excessively exposed to cadmium.
With regard to distribution in other organs, only traces of
cadmium were found in brain of adult mice'after a single in-
jection (Berlin and Ullberg, 1963, Nordberg and Nishiyama,
1972). Some data by Lucis, Lucis and Shaikh, 1972, may in-
dicate that cadmium will more easily penetrate the blood-
brain barrier in rats in the fetal stage. As it was not possi-
ble to quantitate the uptake in-the brain, more data are
needed. In the same work newborns exposed to cadmium via ,,,-.,
milk from the mothers showed a rapid build-up of cadmium con-
centrations in the intestines, but only a very slight increase
in the liver. It is not clear whether the high concentration
-------
-29-
in the intestines was due to a local uptake in the intestinal
walls or to a slow passage of the intestinal contents. Lucis,
Lucis and Shaikh, 1972, also found that cadmium accumulated
in the mammary glands of pregnant rats but only small amounts
were excreted via milk.
4.2.3 Distribution within organs
The subcellular distribution in the rat liver has been
studied by Shaikh and Lucis, 1972b, after injection of
109
Cd as chloride. 24 hours after injection about 80 per-
cent was in the soluble fraction and about 9 percent in
mitochondria and microsomes. Only very small amounts were
found in the nuclei. Webb, 1972a, made similar studies on
rat kidney cortex at different times after subcutaneous
injections of cadmium chloride, 2.4 mg/kg body weight.
With time, the cadmium content of the soluble fraction in-
creased, whereas cadmium content of lysosomes and mitochondria
decreased. After 15 days cadmium was practically absent from
these organelles. There was some increase with time in the
microsomes, paralleling the increase in the supernatant.
Lucis, Lucis and Shaikh, 1972, separated mammary gland soluble
proteins from cadmium exposed pregnant rats, and found that
cadmium was bound to high molecular weight protein and was
not found in low molecular weight protein fractions. Placenta,
however, contained cadmium both in high molecular weight
proteins and in a protein fraction with a molecular weight
of the same size as metallothionein.
Nordberg, 1971a, studied the distribution of cadmium among
cellular organelle.s, free cytoplasma and different cytoplas-
mic proteins in testicles of mice. A homogenate of testicles
was ultracentrifuged at 100,000 x g and the supernatant was
separated by G-75 Sephadex gel chromatography. A change with
-------
-30-
109
time after single subcutaneous injection of Cd-tagged
cadmium chloride (1 mg Cd/kg body weight) was observed. Four
hours after injection 50 percent of testicular cadmium was in
the supernatant and only 26 percent of the cadmium in the
supernatant was in a small protein, corresponding to the
size of metallothionein. The corresponding figures, 4 days
after injection, were 74 percent in the supernatant and 55
percent in the small protein. .
4.2.4 Excretion
4.2.4.1 LJri nj3ry_ £X£r£t^ojn
Earlier investigations (Friberg, 1952) have shown that
only a very small part of the dose was excreted via the
urine provided that there was no renal damage. Attempts
were not made at that time to relate excretion to body
burden.
The very low urinary excretion of cadmium has been verified
by Shaikh and Lucis, 1972a, in rats given a single subcutane-
ous injection. They found a ...daily urinary excretion during
four days of only between 0,i003-0.007 percent of the dose.
Similarly, Nordberg and Piscator, 1972, and Nordberg, 1972a,
found that during repeated subcutaneous exposures to 0.025
to 0.5 mg cadmium/kg body weight f.or up to six months the
urinary excretion in mice was. very low. At the time that
pathological urinary proteins .were observed at electrophoresis
(after 21 weeks) in the group given the highest exposure, there
was a sharp increase in urinary cadmium excretion. It was shown
by Nordberg and Piscator, 1972, by means of gel filtration, that
a large part of the cadmium in urine was bound to proteins with
a molecular weight corresponding to that of metallothionein.
Nordberg, 1972a, b, in the studies referred to above, also
showed that the urinary excretion on.a group basis was signi-
-------
-31-
ficantly related to total body burden (Figure 4:2). At the
highest dose level 0.02 percent was excreted daily, whereas
at the lower dose levels about 0.01 percent was excreted.
However, as seen in Figure 4:3, there is a considerable indi-
vidual scatter.
The. excretion of cadmium compounds in the rat has also
been studied by Furst, Cadden and Firpo, 1972. Cadmium in
urine was analyzed by atomic absorption spectrophotometry
without any special pretreatment for eliminating interferences.
The authors calculated that more than 50 percent of the dose
was excreted in a few days. This is probably an error due to
influence from sodium chloride in the urine as has been dis-
cussed in CITE. No conclusions can be drawn from the studies
with regard to excretion.
109
Murata, 1971, gave oral doses of 10 and 20 yd Cd as chloride
(carrier free) respectively to mice. During the first day about
25 percent and in 3 weeks about 50 percent of the total dose
were excreted with the urine. The total amount of cadmium
in feces. during 3. weeks was only about 25 percent of the
dose. The data do not fit at all with earlier experience (see
CITE), as they indicate an extremely high absorption. Furthermore,
the sum of urinary and fecal excretion was only about 75
percent of the dose in 3 weeks, which would indicate an extreme-
ly high retention. No explanation for these inconsistent
results can be given at present, but some methodological
error must be suspected.
4.2.4.2 Excr£ti_oin via ;tht3 alimentary tract
Shaikh and Lucis, 1972a, found that about 5 percent of a
109
single subcutaneous dose of 2.2 yg Cd as chloride was
excreted via feces of rats during the first 4 days.
-------
-32-
Biliary excretion of cadmium may be of importance (Caujolle,
Oustrin and Silva-Mamy, 1971). Rats were given intraperitoneal
109
injections of Cd as sulfate. The dose was 7 yCi, specific
activity not stated. A relatively constant excretio.n of cadmium
via bile was found up to 6 hours after injection. When the bile
duct of one rat was connected to the small intestine'of another
rat, cadmium excreted via bile was reabsorbed to a certain ex-
tent, indicating an enterohepatic circulation.. However, they
did not present their data in a way that makes it possible
to evaluate this quantitatively...
Nordberg, 1972a, .did not f.ind any 'correlation between total
body burden and fecal excretion of cadmium in mice. When a
larger number of animals were followed in a later study
(Nordberg, 1972b), a certain correlation was found. In Figure
4:4 (where individual data are given), the results are seen
from a group.of mice exposed to 0.025 mg, Cd/kg body weight
5 days/week for about 5 months. It is seen from the figure
that a considerable Individual scatter exists. If a linear
regression analysis is carried-out, a significant correla-
tion is found (r .= 0.42, n = 149). The regression coefficient
is 0.39 and differs significantly(p <0.001) from zero. This
would favor that some part of the excretion is dependent on
body burden of cadmium. On the other^.harid; 'in 'ario'th'e;r exper-
iment in which the daily dose was 10 times higher (Figure 4:5),
it could be shown that the fecal excretion at a certain
body burden also was about 10 times higher. This means that
at the dose levels studied the main part of the excretion .
must be related to the daily dose. Upon two occasions during
the experimentwith the lower doses, exposure was withheld
for three weeks. Observations made after the exposure-free
weeks are shown in Figure 4:4 (unfilled circles). These values
consistently fall below the regression line, further supporting
a relation between fecal excretion and daily exposure. As the
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-33-
average of thase fecal excretion values was higher at the
end of the experiment (14.2 yg/24 h S.D. « 11.0) than in
the beginning (5.1 yg/24 h S.D. = 3.1), part of the excretion
may be related to body burden. .:
4.2.4.3 .Other e_x£retion_ £0.ut e_s_
In CITE, the excretion via hair was mentioned. No further
studies on this excretion route are available. There are
other-excretion routes which may be worth mention. From the
data of Lucis, Lucis and Shaikh, 1972, it can be calculated
that excretion was less than 0.05 percent per gram milk
per day after a single subcutaneous postpartum injection
to female rats. Tanaka et al., 1972, gave pregnant mice 50
yd of Cd (15 yg Cd) in a single intravenous injection
24-36 hours before delivery. In the newborns only 0.09
percent of the dose was found, i.e. the amount excreted via
the placenta. The cadmium concentration in milk was not measured.
Sucklings born to female mice not given radioactive cadmium
were suckled by the female mice which had been given radio-
active cadmium before delivery. Whole-body measurements
of the sucklings showed that after 14 days 0.3 percent of
the dose given the -Bucklers was found in the sucklings.
As some cadmium must have been passed out via the fecss of
the sucklings, the total amount excreted via the sucklers1
milk must have been more than 0.3 percent.
4.2.5 Biological half-time
One of the more important questions with regard to cadmium
metabolism is the biological half-time, extensively dis-
cussed in CITE. Animal experiments had shown highly varying
values for biological.half-time of cadmium depending on dose,
administration, single or repeated exposure, length of observa-
tion period etc. A general discussion of questions on evaluating
the biological half-time can be found in a paper by Nordberg,.
1972a, and in a report by the Task Group on Metal Accumulation,
1973.
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-34-
There is not much new information on biological half-time
in animals, but studies by Webb, 1972a, will be discussed.
He followed rats for up to 82 weeks after a single subcutane-
ous injection of about 2.5 mg Cd as chloride per kg body
weight. Up to 21 weeks 2 animals were killed each week, and.
then two animals at 35 and .82 weeks respectively (Figure
4:6). Maximum levels in liver were reached at about 10 weeks
after exposure and slightly later in kidneys. Val.ij.es at 35
and 82 weeks were only slightly lower than.at 21 weeks. The
interpretation of the results is difficult as the number
of animals at each time is only 2. If the data are taken
at their face value, they indicate a long biological half-
time.in rat kidney. In the liver there was a slightly faster
clearance.
Webb also studied cadmium concentrations in testis and epi-
didymis. In the former organ there was an increase in cadmium.
levels up to at least 18 weeks. This may partly be explained
by the necrosis and atrophy of the organ, which are induced
by the injected dose (2.5 mg Cd/kg). In epididymis maximum
levels were.obtained after 5 weeks, the concentration had
been halved after about 12 weeks and at 82 weeks no cadmium
could be demonstrated there. Also in this organ .some patho-
logical alterations could be expected from the dose injected.
The results by Webb, 1972a, given above for testis and epi-
didymis differ from those reported by. Gunn, Gould and Anderson,
1968a, who also used rats, but gave a non-injurious dose
109
of Cd. They found no., time-related changes in concentration
of cadmium in testis and epididymis from 1 hour up, to 6
weeks after injection. ' ...
The strikingly slow accumulation in all organs studied by
Webb is difficult to account for; one reason may be a re-
tention of the high dose at the injection site.
-------
4.2.6 Influence of other compounds on the metabolism of cadmium
Special attention in this context was paid to selenium and
cysteine in CITE. The possible effect of chelating agents
was also discussed. Some new studies are now available on
the influence of NTA (nitrilotriacetic acid) on the metabolism
of cadmium.
Scharpf, Ramos and Hill, 1972, gave female rats single oral
doses of CdCl_ and NTA. There is all reason to believe that se-
rious methodological errors were introduced because cadmium in
urine was determined with atomic absorption spectrophotometry
without previous extraction or other treatment. Because
of salt effects the urinary values will be too high under such
circumstances. One group of animals was given 64 mg of cad-
mium chloride per kg body weight, which will correspond
to about 10 mg of cadmium to a 250 g rat. The excretion
of cadmium in urine after 96 hours was 1.97 percent of
the dose in rats given cadmium and NTA and 0.76 percent of
the dose in rats given only cadmium. It has repeatedly been
demonstrated that in normal rats absorption of cadmium after
oral exposure is only about 2 percent, indicating that in
this case not more than about 200 y g cadmium per rat was
absorbed. An excretion of 0.76 percent of the dose would
mean about 76 yg, which is more than one third of the dose,
an extremely unlikely figure.
In the same report it was found that in liver and kidneys,
where the results of cadmium analysis probably are more reli-
able than in urine, cadmium concentrations were considerably
lower in animals given cadmium chloride and NTA, than cadmium
chloride alone. This has also been shown by Scharpf et al.,
VJ72, in another experiment on rats in which cadmium chloride
was given without NTA to one group and with NTA, 200 mg/kg
body weight to another group. Liver levels of cadmium were
more than 3 times higher in the group given cadmium chloride
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alone. Whether .this is due to a lower absorption or to a
higher excretion when cadmium is given together with NTA
is not known. :
Nolen et al., 1972, and Nolen, Bohne and Buehler, 1972, studied
the effects of NTA on cadmium metabolism in rats. Nolen et al.
gave groups of pregnant rats cadmium a^__t_hechj.^ji-de in drinking
water so that the exposure was Q, 0.01, 1 and 4 mg/kg body weight
per day. Sodium-NTA was given in water in doses corresponding to
0, 0.1 and 20 mg/kg body weight per day. Exposure time was be-
tween days 6-14 of the gestation period. On day 21 the animals
were killed. At all cadmium exposure levels there were no dif-
ferences in cadmium content of liver and kidneys between animals
without or with NTA.. In the study by Nolen, Bohne and Buehler,
pregnant rats were studied under similar, conditions as above.
Cadmium was given in oral doses of 4 mg/kg/day. Na_NTA was given
in a dose of 20 mg/kg/day and also in that dose together with
FeCl_ (7 mg per kg/day). One group was given.sodium citrate
(20 mg/kg/day). This time, rats given' NTA or NTA + Fe had
significantly higher cadmium levels in liver than animals given
only cadmium. Citrate also caused higher liver levels. In kid-
neys both NTA and citrate.caused higher cadmium levels.
Nordberg, 1971b, gave 0.1 percent NTA in the drinking water for
3-4 weeks to one group of 4 mice and ordinary tap water to another
group of 4 mice. Both groups were given 7 yg Cd/kg in the form
109
of CdCl_ via stomach tube on the third day of the experiment.
The body burden of cadmium as well as the excretion of cadmium
in urine and feces was followed by measurements of radioactivity.
Three days after the cadmium exposure, the NTA-group had retained
9.7 percent of the, administered dose and. the other group 18 per-
cent. Seven days after dosing, the corresponding figures were'
1.9 and 1.8. percent, respectively and 14-18 days after dosing
1.6 and 1.6 percent, respectively. The mice were killed 24-29
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-37-
days after dosing. The mean liver concentration of cadmium in
the NTA-exposed group was 0.53 ng/g (range 0.27-1.05) and in
the non-exposed group 0.76 ng/g (range 0.24-1.53). Kidney con-
centrations were 1.41 ng/g (range 0.92-2.70) in the NTA-group
and 1.62 ng/g (range 0.76-2.38) in the control group. In
short, no large difference in organ retention was found.
Nordberg, 1972c, also studied liver and kidney retention of
radioactive cadmium in mice which had .been given a single sub-
109
cutaneous. injection of CdCl- (0.1 yg Cd/kg body weight).
They then drank water containing 50 ppm non-radioactive
cadmium for several months. Half of the 38 mice in the study
were also exposed to 500 ppm NTA in the drinking water.
At the end of the observation period (4 months) 14 mice
in the cadmium-NTA group were alive versus 11 in the control
group. The mean concentration of radioactive cadmium in
liver and kidney of the surviving mice was as follows: Group
Cd + NTA: Liver 1.18 ppm (wet weight); kidney 0.98 ppm.
Group Cd: Liver 1.33 ppm; kidney 1.21 ppm. That is to say,
no large differences in cadmium concentrations were observed.
4.3 TRANSPORT, DISTRIBUTION AND EXCRETION OF CADMIUM IN NORMAL
AND EXPOSED HUMAN BEINGS
4.3.1 Transport and distribution in blood
Reviewing data from various countries, it was concluded in
CITE that the average normal cadmium level in whole blood in
normal human beings is well below 1 yg per 100 ml whole
blood. The main difficulty in assessing normal values
has been that the analytical methods have not yet been
so perfected so as to measure accurately these small quantities
of cadmium in blood. To date, no accurate studies on analytical
methods have yet been carried out.
Vens and Lauwerys, 1972, found a mean concentration of 0.95
y'g/100 ml whole blood (S.D. 1.0) in 24 normal subjects. (See
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-38-
also Chapter 2). In the red cells a mean concentration of 2.16
pg/100 ml (S.D. 2.69) was reported. The concentrations in whole
blood are somewhat higher than those earlier reported. It is
not quite clear from the paper whether the values for cadmium
in red cells were obtained by actual determinations, or by the
assumption that all cadmium was in that fraction and the use
of hematocrite values.
Another recent report on normal values is by Delves, Bicknell
and Clayton, 1972. They found a mean value of 0.49 ug per 100
ml.(atomic absorption after extraction, in organic solvent) of
whole blood in healthy children as^ compared with 0.57 in a1
group of children admitted to a 'hospital. The highest individ-
ual value noted in-the group of patients was 7.9 ug per 100
ml. Such a high value has only been seen in cases of heavy
occupational exposure to cadmium. Cadmium concentrations in
serum have been determined in patients with and without hyper-
tension by .Hertz, Koschnick and W'i;lk* .1972. In CITE a .
report by Plertz et al., 1968, was discussed and it .was
concluded that the values presented were too high for
cadmium in. serum. The same can be said of the report on
the hypertensive patients. Hertz, Koschnick and.Wilkj 1972,
obtained a mean cadmium concentration in serum of 23 u.g/100
ml, and the maximum value was 80 u.g/100. ml. As this is
a value which considerably exceeds even concentrations
obtained in experimental studies involving radioactive
cadmium isotopes on severely poisoned animals, some serious
analytical errors must have been involved. (See also
section 4.3.4.1, where this method gave a urinary cadmium
excretion of almost 1 mg/day).
There are also some new data on cadmium in the blood of exposed
workers. Piscator, 1972, studied a group of 2.5 workers in.
an alkaline, battery factory and related cadmium concentrations
-------
in blood (spectrographic method, "normal" concentration < 0.2
yg per .100 ml) to exposure time but found no relationship
(Figure 4:7). Short exposures could be combined with high
concentrations in blood and long-term exposure with low concen-
trations of cadmium in blood. In another study (Piscator,
unpublished data) it was possible to follow the decline in
blood levels of cadmium in a group of about 20 people, who
for 1-2 years must have been very heavily exposed to a cadmium
aerosol during polishing of cadmiated metal. Extremely high
levels of cadmium were found in blood, after which the operations
were closed down and the workers moved to another workshop.
Cadmium in blood was determined 3 and 9 months after cessation
of exposure (Figure 4:8), and during that period the half-time
of cadmium in blood was about half a year.
4.3.2 In organs
Available data on concentrations of cadmium in organs, espe-
cially liver and kidneys were presented in CITE. In some
European countries and the United States, liver concentrations
in adults were between 1 and 3 ppm wet weight, whereas
in one area in Japan, regarded as not cadmium contaminated,
levels in adults between 50 and 75 years of age reached
above 10 ppm. In renal cortex levels of 20-30 ppm wet weight
at age 50 were found in the United Kingdom and Sweden,
whereas in the United States, the corresponding value was
about 50 ppm. Higher values were reported from Japan, where
in one area classified as non-polluted, an average level
of 90 ppm was reached at age 50.
Some new data on kidneys have now been obtained and are pre-
sented in Figure 4:9. At around age 50 cadmium levels in
cortex from men in East Germany are 25-30 ppm wet weight,
whereas in women from the same country the concentration is
around 15 ppm (Anke and Schneider, 1971). Corresponding figures
-------
-40-
for men and women in the United States (North. Carolina) in
a new study by Hammer and Finklea, '1972, are 26 and 24 ppm
wet weight. Even in other age groups the difference between
levels in men and women was not as great as in the report from
East Germany. In contrast to these data, Tsuchiya, Seki and'
Sugita, 1972, (Figure 4:10) reported a mean level around
125 ppm wet weight at age 50- in Japanese (the group consisted
of both men and women) from the Tokyo area which in' Japan
is regarded as a non-contaminated area.
In Figures 4:9 and 4:10,data by Kitamura, Sumino and
Kamatanni, 1970, Ishizaki, Fukushima and Sakamoto, 1970,
and Schroeder and Balassa, 1961, are also included, together
with data on Swedish workers as reported in CITE.
The new data confirm the earlier reported results. In Europe
average cadmium concentrations in renal cortex at age 50 will
be 20-30 ppm and in so-called non-contaminated areas in Japan,
up to 125 ppm. All the group averages from Japanese areas are
higher than corresponding values from Europe and USA.
The linear increase as described in CITE has been confirmed.
Earlier data from the USA showed a renal cortex level of about
50 ppm at age 50, whereas lower values now have bee.n reported
in other studies. Whether regional differences in relation
to exposure or other factors may explain the differences
is not known.
4.3.3 Distribution in organs
Further information on the distribution of cadmium in kidneys
has been obtained by analysis of serial sections (Livingston,
1972). From the outer layer of the cortex and inward, 8 hori-
zontal layer sd'ctions, 4 cortical and 4 medullary, were cut
and analyzed for cadmium, zinc and mercury by neutron activa-
-------
-41-
tion analysis. An example is shown in Figure 4:11. The con-
centration of cadmium was found to decrease from the outer
layer inward. In the illustrated case, the content in
the outer cortex was about twice as high as in that in
the inner cortex nearest the medulla. These data clearly
show the necessity of standardizing sampling methods.
4.3.4 Excretion
4.3.4.1 Urina_ry_ e_x£r£31jiori
In CITE it was concluded that normal excretion of cadmium
via the urine is vary low, around 2 yg/day or less.
Suzuki and Taguchi, 1970,. studied 38 men with a mean age
of 29 years (18-44 years) and 49 women, mean age 27 years
(16-49 years) from the Tokyo area. They found a mean ex-
cretion of 2.38 yg/1 in the men and 1.97 yg/1 in the women,
but did not find any relationship between age and excretion
of cadmium. Katagiri et al., 1971, determined cadmium in
urine in 303 persons (males and females, ages 4-59) from
Gifu in Japan. At ages 4-6 the average urinary concentration
was 0.47 yg/1, in age group 30-35 1.13 yg/1 and in age
groups 40-49 as well as 50-59 1.75 ng/l. Similar results
were obtained by Tsuchi.ya and Sugita, 1971, and Tsuchiya,
Seki and Sugita, I972a, who studied 609 inhabitants of
Tokyo (Figure 4:12). From age 5 to 35 years there is an
increase in cadmium excretion from about 0.5 to 2 yg/1.
Then the excretion is of about the same magnitude to age
55 after which it falls slowly off. Piscator, 1972, found
in 10 men, ages 34-63 years, living in a polluted area
in Sweden, a mean concentration of 2.1 yg/1. In CITE it
was mentioned that in urines from 10 persons in Stockholm,
Sweden, 20-40 years of age, the average cadmium excretion
was 0.4 yg/day, corresponding to a concentration of 0.34
yg/1 (0.07-0.63). All determinations reported here have
been made by atomic absorption spectrophotometry after
extracting with a chelating agent into an organic solution.
-------
-42-
There are also two reports,by McKenzie M972a, 1U72b). These
data cannot be used because cadmium was determined with atomic
absorption without extraction, giving extremely high values.
The mean excretion was reported to be 36 and 33 yg Cd/24 hours
in men and women respectively. Mertz, Koschnick and Wilk, 1972,
have reported on cadmium excretion in hospitalized persons, with
and without hypertension. They used a spectrographic method and
found a mean excretion of 0.63 yg Cd/min, which would correspond
to a mean daily excretion of 913 yg,.-which is much higher than
ever reported in groups of cadmium.workers. This is the same
method that gave erroneously high results for cadmium in serum.
One main difficulty in evaluating urinary excretion of
cadmium in exposed workers as described in much of the
data at hand is the fact tha.t it has not always been made
clear whether or not tubular dysfunction also existed,
which could have caused an increased excretion. This
problem was mentioned in CITE and Piscator, 1972, has taken
some steps to clarify it. He studied urinary excretion
of cadmium in workers exposed to cadmium oxide dust in an
alkaline battery factory. In 27 wo.rkers and ID controls urinary
cadmium, total urinary protein and urinary 3--microglobulin-
were determined and electrophoretic separations of urinary
proteins were performed. All analyses were blind, without
knowledge of exposure conditions. Even in cases with long
exposure time [ >5 years) but without signs of renal dysfunc-
tion, urinary cadmium generally was below 1.0 yg/g creatinine.
In workers with-signs of renal dysfunction as indicated
by changes in electrophoretic patterns and increases in
6,-microglobulin, urinary excretion of cadmium was higher
(Figure 4:13).:, It seems that in that type of industry,
where concentrations of cadmium .in air during the last
3
ten years usually had been around 0.05 mg Cd/m , cadmium
excretion could not be related to body burden, whereas
renal dysfunction caused an increase in the excretion.
-------
-43-
There are many difficulties in interpreting these data,
however, especially since it is difficult to estimate the
individual exposures.
In the study by Piscator (unpublished data) referred to in
section 4.3.1, high concentrations of cadmium in blood as
well as in urine were observed in workers after 1-2 years
of exposure to high concentrations of cadmium. After exposure
had ceased, large individual variations were found and
no regular patterns were seen (Table 4:2). In some cases
there were no important changes with time while in other
cases considerable decrease or increase in urinary cadmium
excretion was observed. In most cases protein patterns were
normal. Total protein excretion was in all cases.within 'the
normal limits but as seen in Table 4:2, the relation between
different proteins varied. Pathological patterns were sometimes
seen on paper electrophoresis.
According to Tsuchiya, Seki, and Sugita, 1972b, protein ex-
cretion will increase first at a cadmium concentration of
about 50 yg/1 of urine. Such a conclusion does not seem
to fit with the data presented above by Piscator, 1972.
Tsuchiya and collaborators studied only total protein content.
It should be pointed out that protein concentrations in
urine may well be within normal limits coincident with
slight tubular dysfunction, as shown by increases in 3~-
microglobin and changes in electrophoretic patterns. Piscator
studied such early signs of tubular dysfunction. Furthermore,
in the Swedish study the workers were exposed to cadmium
oxide dust, while in the Japanese study the workers were
exposed to cadmium oxide fumes. The Japanese workers had
very high blood levels, highest around 40 yg/100 ml.
The study by Tsuchiya, Seki. and Sugita, 1972b, would be
more comparable with the other study by Piscator (unpublished
data) in which the exposure was heavy but over a fairly
-------
-44-
short period of time. The blood values were high and high
amounts of cadmium were excreted in the absence of signs
of renal dysfunction. Nomiyama, 1971a, found 5.8 (1.9-13.7)
yg Cd/1 in the urines of 9 persons without proteinuria (Tri-
chloracetic acid method) compared with 19; 8 (17.3.-21.2)
yg Cd/1 in 3 persons with proteinuria.
Sudo and Nomiyama, 1972, studied urinary excretion of cadmium
in a 6-1-year-old male so-called cadmium worker with proteinuria
varying between - and ++. Cadmium excretion as measured in
three daily urine specimens was studied during one month and
showed marked variation (10-50 yg Cd/24 h). Spot samples were
also studied for six months. The authors pointed out the
necessity for expressing excretion values on a per-day basis
rather than on a per volume basis.
Summing up, there are data which may seem to contradict each
other. Japanese studies on people not occupationally exposed
to cadmium show an increase in cadmium excretion on a group
basis which seems to be related to body burden. A similar
association with exposure could not be found in Swedish workers
exposed for several years to cadmium oxide dust and without
signs of tubular dysfunction. Likewise, in workers having
undergone a short but very heavy cadmium exposure and having
high blood and urinary values of cadmium, the urinary excre-
tion after cessation of exposure did not follow body burden
in a predictable way based on the Japanese data. Exposure
situations thus seem to be of paramount importance.
4.3.5 Total body burden and renal burden
In.CITE it was concluded that the body burden at age 50 in
non-contaminated .areas in Europe was 15-20 mg, in the U..S.
30 and in Japan 40-80 mg.
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-45-
Tsuchiya, Seki and Sugita, I972a, calculated total body
burden and renal burden in autopsy studies from Tokyo. The
total body burden was assumed to constitute double the amount
found in liver and kidneys. At 10-30 years of age, total
body burden was about 30 mg, at 30-50 years about 45 mg
and at the age of 50-59 about 55 mg. The renal burden at
age 50 was about 20 mg. In CITE it was concluded that total
body burdens in Europe and the United States were about 15-
30 mg at age 50 and so the data by Tsuchiya, Seki and Sugita
give further support to the statement that even in so-called
non-polluted areas in Japan body burdens of cadmium are
considerably higher. The difference will be even more evi-
dent if body burden is expressed as mg/kg body weight.
In CITE it was calculated that smoking a pack of cigarettes
a day for 35 years might result in 30 percent higher renal
cortex levels of cadmium in smokers than in non-smokers.
Lewis et al., 1972, determined cadmium in kidney, liver and
lung in 45 male smokers (mean age 60, S.D. 11 years) and
in 22 male non-smokers (mean age 60, S.D. 12 years). It was
possible to calculate the number of "cigarette pack years"
for each smoker. In non-smokers cadmium in kidney, liver and
lung was on an average 6.6 mg while in smokers the corresponding
figure was 15.8 mg. A significant association was found between
number of pack years and cadmium accumulation (Figure 4:14)
also when age was controlled for.
4.3.6 Biological half-time
It is evident that the data covered in CITE spoke in favor
of an extremely long biological half-time (decades) for cad-
mium. This conclusion was based on a model for cadmium accu-
mulation in the body implying that one third of the body bur-
den was in the kidneys. The great need for further studies
on the biological half-time was pointed out.
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-46-
In section 4.1.1.2 the details are given of an investigation
I
by Rahola, Aaran and Miettinen, 1971, in which radioactive cad-
mium was given, to male volunteers. The .decrease in whole-body
retention of radioactive cadmium was very slow from 20 days
to 2 months after exposure. It was not possible to give an
exact value for the biological half-time for this slow com-
ponent. The shortest estimate was approximately 130 days;
the longest one was infinity.
\ ...
Intermittently during six months, Sudo and Nomiyama,.1972, .
measured urinary cadmium excretion from a so-called former
cadmium worker who had proteinuria (see section 4.3.4).-Cal-
culating the biological half-time, they arrived at a value of
about 200 days. The authors did not account for the uncertainty
in the value, which must have been considerable because of
the reported marked variations in the daily urinary excretion
and the short observation period compared to the/biological
half-time. These drawbacks along with the facts that the person
had proteinuria and that his fecal cadmium excretion was not
taken into account render it impossible to consider the value
given by Sudo and Nomiyama as valid.
In some recent papers various mathematical models have been
discussed, in some cases based on observed cadmium concentrations
in autopsy materials.
Calculations of the biological half-time of cadmium based
on autopsy data and calorie consumption were performed by
Kje-llstro'm, 1971 ^Tsuchiya: and Sugita., -,19,71, and':Ts':uchry,a.,,
Sugita and Seki, 1972. Biological half-times of from 16
years (Tsuchiya and Sugita, 1971) to 33 years (Kjellstrom,
1971) have been suggested. Tsuchiya, Sugita and Seki, 1972,
calculated the biological half-time to be 17 years for the
\
kidneys and 6.2 years for liver. The.basis for the calculations
-------
were data on renal and liver burdens of cadmium obtained by
autopsies on inhabitants in Tokyo. Hammer and Finklea, 1972,
estimated the biological half-time for the whole body to be
9-18 years. They reached this value by using the same model
and the same intake figures as given in CITE and applying
these to some new autopsy data (section 4.3.2, 25 ppm at
age 50).
Both in the paper by Kjellstrom, 1971, and by Tsuchiya, Sugita
and Seki, 1972, it was pointed out that several parameters
must be taken into account when calculating the biological
half-time, such as changes in food intake, changes in kidney
weight with age. In an elaboration on this point, Kjellstrom
and Friberg, 1972, showed how various types of changes in
exposure over the years can affect accumulation (as seen
in cadmium concentrations in organs). A general discussion
of various models used for calculations of toxic metals has
been given by Nordberg, 1972d, and by the Task Group on Metel
Accumulation, 1973).
Conclusion
The question of the exact biological half-time of cadmium in
the human body is still under discussion. All data continue to
favor a very long biological half-time.
4.4 -RELATIONSHIPS AMONG CONCENTRATIONS OF CADMIUM IN BLOOD,
URINE AND ORGANS
4.4.1 Relationships between concentrations of cadmium in
blood and in organs
4.4.1.1 !n_ainima_ls_
In CITE it was stated that more data were needed before any
definite conclusions could be drawn. There are now some ad-
ditional data available. Nordberg, 1972a, found that if animals
-------
-48-
were . in jected subcutaneous ly for 3 weeks by small doses of
cadmium chloride and then exposure ceased, blood levels during
3 weeks decreased with about 40 percent. Whole body burden
did not decrease noticeably, indicating that there was
no relationship between blood levels and body burden.
4.4.1.2 ^n
In the investigations mentioned in section 4.3.1 (Piscator,
1972) it was found that there was no relationship between
cadmium levels in blood and exposure time. 'Nor was there
any relationship between degree of proteinuria and blood
levels. No relationship could be found between levels of
cadmium in blood and urinary excretion of cadmium. In other
investigations in which there had been short-term high expo-
sure to cadmium, a relationship between urine and blood values
seemed to exist (Tsuchiya, Seki and Sugita, 1972b).
4.4.2 Relationships between concentrations of cadmium in
urine or feces and organ or blood concentrations
4.4.2. 1 .1 n__
From the data evaluated in CITE, ,it seemed as though the
excretion of cadmium was dependent primarily upon, the daily
dose and only to a limited extent reflected total body burden.
Nordberg, 1972a,b, has now shown that there is a relationship
in mice on a group basis between urinary excretion of cadmium
and total body burden, before renal damage has occurred (4.2.4.1).
The excretion via feces is dependent on the daily dose but a small
part of it also may be dependent on body burden (4.2.4.2).
4.4.2.2 J.n_
Concerning, fecal excretion, in CITE no data which 'could show
to what extent a fecal excretion of cadmium takes place .were
quoted. To date, there are still no data available to give any
grounds for such a discussion.
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-49-
In CITE it was stated that the main part of the cadmium
excretion via urine was unrelated to renal accumulation but
related to the daily dose. There are still no conclusive data
which c.ould show whether or not a relation to renal burden
exists. The Japanese studies referred to in section 4.3.4.1
(Katagiri et al, 1971, and Tsuchiya, Seki and Sugita, 1972a)
show a relation to total body burden on a group basis
during long-term low exposure to cadmium. Due to the wide
individual scatter the predictive value of urinary cadmium
as an index of total body burden on an individual basis is
low. Furthermore, data from exposed workers (4.3.4.1) show
that in other exposure situations a similar relation with body
burden may be absent. There is a great need to study, under
different exposure situations, urinary excretion in relation
to concentrations in different organs. Under certain condi-
tions and on a group basis it may well be that urinary cadmium
is a useful index of accumulation of cadmium.
4.4.3 Conclusions
It was previously stated that no data existed which could
show that the concentration of cadmium in blood or urine could
be used for estimating organ levels of cadmium in human beings.
The investigations, both on animals and normal human beings,
discussed in the foregoing sections indicate that in human
beings, having a normal renal function and not excessively
exposed to cadmium, there might exist a relationship between
urinary excretion of cadmium and total body burden on a group
basis. Due to a wide scatter, the predictive value is low on
an individual basis. It is not known to what extent the excretion
is related to the concentration in the critical organ. During
exposure situations which may occur in factories, relations
between body burden and cadmium excretion may be quite different.
4.5 METALLOTHIONEIN
In CITE some data were given on the unique properties of this
'metal binding protein, characterized by a low molecular weight.
-------
-50-
absence of aromatic amino acids, and a high percentage of
cysteine in the molecule. Metallothioneins or proteins very
similar to metallothionein were thought to play an important
role for transport of absorbed cadmium and also .for the
transport of cadmium to the kidneysi
During the last years many reports both on the occurrence
and chemistry of metallothionein have been published. Proteins
similar to metallothionein have now been identified not only
in liver, kidney and duodenum, but also.:in other organs of
animals exposed to cadmium. Shaikh and Lucis, 1971, found two
forms of rat metallothionein, with slight differences in amino
acid composition in liver, kidney,, spleen .an.d pancreas. Nordberg,
1971a, treated mice with non-radioactive cadmium, 0.25 mg Cd/kg,
for 12 days and then gave -a high dose of radioactive cadmium
.1 mg Cd/kg. In mice not .given this pretreatment, the high dose
caused testicular damage, whereas the h'igh dose had no effect
on the testis of pretreated mice. In mice that had not received
any pretreatment with non-radioactive cadmium, it was found
that most of the injected radioactive cadmium was in high molecu-
lar weight fractions 4 hours after the injection. In contrast,
most of the radioactive cadmium in pretreated mice was found
in a low molecular weight fraction, corresponding to metallo-
thionein. It was concluded that this was one of the reasons
that cadmium did not cause testicular damage at repeated injec
tion. There are also two brief reports by Singh and Nath, 1972,
and Chen et al., 1972, on the occurrence of a low molecular
weight protein containing cadmium and thiol groups in testis
of rats given an intraperitoneal and subcutane.pus injection
109
of Cd, respectively. .
A similar protein was also found in rat placenta, while in
the lactating mammary glands of rats, cadmium was only found
in high molecular weight protein fractions (Lucis, Lucis and
Shaikh, 1972). . .
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-bl-
Some further data on the chemistry of metallothionein have been
provided by Webb, 1972b, who suggested that in contrast to horse
liver metallothionein, rat liver metallothionein needed only two
SH-groups to bind cadmium. According to Webb these rat proteins
are heat resistant, a property which can be used in the prepara-
tion of the protein. Webb, 1972b,c, has also thoroughly dis- .
cussed the evidence behind the claim that metallothioneins
are mainly synthesized in response to exposure to cadmium and
zinc. Webb could stimulate synthesis of zinc-containing cadmium-
binding low molecular weight proteins by giving injections
of zinc, which is in contrast to earlier reported results of
Shaikh and Lucis, 1970, who could not induce synthesis of cadmium
binding proteins by giving zinc. The purity of the zinc compounds
given was not stated in either case. As zinc salts may contain
cadmium as an impurity, this amount of cadmium may be enough
to stimulate synthesis.
Webb, 1972a, when separating liver and kidney supernatants by
gel filtration, also found some slight differences in hepatic
and renal low molecular weight cadmium binding proteins. He
found that they differed in electrophoretic mobilities.
That there are different forms of metallothionein has
bean shown by Nordberg et al., 1972, who obtained two major
.forms of rabbit liver metallothionein with different metal
contents and different isoelectric points by using isoelectric
focusing. The two major forms were then subjected to amino
acid analysis, which revealed that the amino acid composition
of both forms was very similar and also similar to metallothionein
from horse kidney, earlier characterized by amino acid analysis
by Kagi, 1970. Some differences between the rabbit liver
and horse kidney proteins were notable, i.e. the rabbit protein
.lacked the arginine, valine and leucine reported in the horse
p ro t e i n .
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-52-
The two forms of metallothionein purified by Nordberg et al.
differed as to their contents of lysine, proline and gluta-
/Date. One of these forms contained cadmium and zinc in a
molar ratio of 50:1 and the other one.in a ratio of 1:1.2.
The total molar amount of metal was about the same in both
forms. The differences in electrophoretic mobilities and i'n
isoelectric points may be due to both different .charges, and
sizes, dependent on metal content and type of metal, but
also on differences in amino acids. A third form, containing
only zinc, was also observer!, but in smaller amounts, which
did not allow further characterization.
More data on horse metallothionein.have.been given by Roosemont,
1972, who found two. metalloproteins in horse renal cortex. These
differed in metal content and in ratios between ca.dmium and zinc,
The ability of mstallothionein to bind mercury has also at-
tracted further interest and Wisniewska-Knypl et al., 1972,
and Piotrowski ,et al., 1972, have recently been .able to iso-
late a mercury-binding metallothionein from rat.liver. It was
shown that the molecular weight was around 10,000, determined
by gel filtration and that this protein had the absorption
curve typical for metallothionein. Injections of mercury did
not induce synthesis of metallothionein to the same extent as
cadmium, and in these experiments it was .also necessary to
inject cadmium to stimulate the production .of metallothionein.
It has not been shown that exposur.e to mercury alone causes
increases in mstallothionein in the liver, but in the kidney.
an increased amount was found after exposure to mercury
(.Piotrowski et al., 1972).
Bryan and Hayes, 1972, claim that they found an increase in
low molecular weight metal binding proteins in liver of mice
after oral exposure to mercury chloride for several weeks.
They separated soluble liver components on a short Sephadex
-------
-53-
G-75 column (void volume 4.2 ml) at pH 7 and with an eluant
of very low ionic strength, and found increases in the 250/280
nm ratio in the low molecular weight fractions, which they
estimated to have a molecular weight of 11,000. This estima-
tion cannot be correct. It is difficult to see how reliable
molecular weight determinations could be obtained on such a
small column without a valid marker procedure. Moreover, a
careful examination of the gel filtration patterns in the
report reveals that the fraction which is called low molecular
weight protein must be composed of compounds probably in the
molecular weight range of amino acids.
It should be pointed out that molecular weight determinations,
performed by gel filtration, have shown a molecular weight
around 10,000 in most studies. Data by Nordberg et al., 1972,
confirmed earlier results by Ka'gi, 1970, that when using the
results of amino acid analysis,.the true molecular weight of
thionein is probably 6,000-.7,000.
In a report by Nordberg, 197la, a pharmacological approach
was chosen to study the effects of administration of metallo-
thionein to mice. Graded doses of metallothionein were injected
together with cadmium and zinc and it was observed that al-
though the total dose of cadmium was the same in all groups
(1.1 mg/kg body weight), animals which were given a certain
amount of metallothionein were protected from the testicular
damage evident in the group not given any metallothionein.
In the mstallothionsin injected group histological evidence
of tubular kidney damage was observed. This is in accordance
with earlier theories that cadmium bound to metallothionein
will be filtered through the glomeruli.
Regarding metallothionein in human beings our knowledge is
still minimal, but some additional information has been ob-
tained from the report by Wisniewska-Knypl, Jablonska and
-------
-54-
Myslak, 1971, who investigated a case of acute cadmium poi-
soning in a man'who swallowed large amounts of cadmium iodide
(25 rog Cd/kg body weight) in a suicidal attempt. He suffered
anuria, amo.ng other things. Treatment with a calcium EDTA
compound was tried but did not improve his condition and he
died after 7 days. Cadmium accumulated mainly in the liver
and renal cortex, and it was possible from these two organs.
to identify low molecular weight cadmium protein complexes ""
by separations on Sephadex G-75. In renal medulla, testis
and heart, the main cadmium fraction was also found in a low
molecular weight fraction.
From the studies, reviewed it is further supported that metallo-
thionein plays an .important role in the metabolism of cadmium.
There are, however, some points that have to be clarified. It
has been shown that in the liver, there are several forms of
metallothionein with slightly different properties, due to
differences in metal content among other things. In the kidney
two forms of metallothionein have also been found. It is not
known if the proportion between these two forms is the same
i'n liver and.kidney or if there is some selective transport
of one of .these from the liver to the kidney.
.4.6 GENERAL CONCLUSIONS ON .METABOLISM
4.6.1 In animals
Uncertainties with regard to absorption rates after inhalation
still exist and demand extensive investigations. Further data
on intestinal absorptiqn have been provided, showing that
both after exposure to cadmium via drinking water and via
rice, calcium deficiency .will cause a considerable increase
in absorption. The initial accumulation of cadmium in red
cells followed by a decrease and later.by a new accumulation
has been.confirmed. It has also been shown that this redistri-
bution is connected with a build up of metallothionein in
the cells.
-------
-SB-
Repeated exposure to small amounts of cadmium results in its
continuous build up in liver, kidneys and other organs. When
renal tubular dysfunction occurs, urinary excretion of cadmium
increases. Cadmium levels in the kidneys may even decrease.
The accumulation in liver and kidneys seems to be mainly de- ,
pendent on the storage of cadmium in the cadmium binding pro-
tein, metallothionein. It has been shown that this protein
may easily pass through the glomeruli. The urine of exposed
animals with tubular proteinuria has been found to contain
this protein-
Urinary excretion of cadmium in mice has been shown to con-
stitute 0.01 to 0.02 percent, depending on the exposure lev-
els, of the total body burden before renal damage has occurred.
Urinary excretion of cadmium in mice on a group basis is
proportional to the total body burden.
4.6.2 In human beings
Further studies on the fate of radioactive cadmium in human
beings after ingestion have shown that the earlier reported
results for one person, showing an absorption of about 6 per-
cent, were an accurate estimate. In 5 human beings it was
shown that 4.7 to 7 percent of the dose was retained in the
body. It was estimated in CITE that an absorption of about
10 percent of ingested cadmium must be considered possible
under certain circumstances, such as calcium and protein de-
ficiency. Assuming that the influence of calcium deficiency
is of the same magnitude in human beings as in animals, it
is conceivable that absorption rates even higher than }0 per-
cent may occur.
It was earlier shown that in workers who had ;been removed from
an exposure of several years to relatively low concentrations
of cadmium, blood levels decreased faster than body burden. New
-------
-------
-57-
but it is obvious that the biological half-time of cadmium
is extremely long. A proper accumulation model for cadmium
in different organs, including the kidneys, has yet to be
found.
More data have been presented showing that in exposed workers
there is neither a relationship between exposure time and cad-
mium concentrations in blood, nor between cadmium concentra-
tions in blood and urinary excretion of cadmium. The state-
ment in CITE that "the determination of cadmium in blood
will be of limited assistance for making estimates of renal
concentrations" still seems to hold true.
-------
-------
-------
"9/9
2000
1000
Hours
o o concentration In blood cells
o o concentration In plasma
FIGURE 4:1
Concentrations of cadmium in plasma and blood
cells respectively in mice given a single
subcutaneous injection of 1°9CdCl2 M irg Cd/kg)
and Killed various times after injection.
Vertical bars indicate ranges and circles
mean values (From Nordberg, 1972a).
-------
wgCd/24hrs In urine
y = 0.0l5 + 0.00020-x
f = 0.98
0.15 J
0.1
-------
BO
n
50
o
o,
c
O
c . >.
o
o» ° I
. o
500 600 TOO
IM)
FIGURE 4t3 Individual values on urinary excretion of cadmium
related to body burden. All mice were given s.c.
injections 0.25 mg Cd/kg body weight per day.
(5 days per week). ''
one group
°- another group, treated in the same way.
(From Nordberg, 1972b and unpublished data).
-------
"B/Mh
Infecei
120-
iio-
too.
80-
80.
70.
60.
SO-
40.
30
20
line icier* to filed circlet
N-149
y «13.45 »0.43«
f >0.42
e
e
to
20
30
40
SO
60
TO
FIGURE 4:4 Individual values on fecal excretion of cadmium
related to body burden. All mice were given s.c.
injections 0.025 mg Cd/Kg body weight per day
(5 days per week).
during or immediately after exposure
o-3 weeks after exposure
(From Nordberg, 1972b).
-------
FIGURE 4:5 Individual values on fecal excretion of
cadmium related to body burden. All mice
were given B.C. injections 0.25 nig Cd/kg
body weight per day. (5 days per week).
(From Nordberg* 19725).
-------
CD
C
m
CD
^ o o
"Tl *} Bt-
n TO Q.
O 0» 3
(0 c
5- a
10 at "
cr -*>o»
cr-rr 3
(DO.
n
-» N
to co K^
->vl 3
MOO
Ol
*- o
»* o
3 3
CD (D
O 3
rt- rt-
H- 1
O Ot
~~ 3 rl-
CD -.
O
O 3
-*jtD
n H-
Q. 3
r>
«-* 1
NI m
25
I6O
I4O
120
IOO
8O
40
20
0
eo
20
o>
3-
o
o
*c
N
(b)
25 50 1
9 13 17 21
35
82
(d)
25 50
Hours
13 17 21
Weeks
35
82
Contents of Zn*+ and Cd1 * in (a) testis, (b) liver, (c) epididymis and (d) kidney at various times after the subcutaneous
injection of CdCl2 (2*2 /imol/100 g body wt), into adult male rats. Details of the analytical procedures are given in the Legend to
Text-fig. 4 and the 'Materials and Methods' section. Cd2 *-injected animals: A, Cd1+ content; , Zn2* content. Control animals:
O, Zn?* content.
in
-J
-------
5T»
Cadmium in blood
g/lOOml
3-
2-
1-
Noimalor glomerulat proleinuno
*Tubulai proloinnria
*
9
10
15
20 25
Exposure lime
in years.
FIGURE 4:7 Relationship bnt.wson nxponure timn and
cadmiuni conoontratinnR In blood nnmng
wnrknrB in an alkalirm battnry factory
(Frnn. Pincntor. 197?).
-------
Cadmium in whole blood
12
10
8
6-
4-
3
1
0.7
0.5
0.3
0.2
0 1 2 34 55 7 89
Exposure ceased
Months
FIGURE 4:8 Cadmium concentrations in blood in workers
during and after exposure (Piscator, un-
published data).
-------
60
50
40
30
20
10
Cadmium in renal cortex
ppm wet weight
0
25
50
75
Age in years
I <* USA. (From Schroeder and Balassa, 1961).
II *> Men, East Germany (From Anke and Schneider, 1971).
Ill « Women, East Germany (From Anke and Schneider, 1971).
IV - Men, Sweden (From Piscator, unpublished data).
V » USA. (From Hammer and Finklea, 1972).
FIGURE 4:9 Cadmium concentrations in renal cortex from
normal human beings in different age groups
(mean values).
-------
500
400
300
200
100
ppm wei waigni
STH
75
Agi; in yotns
fr workers without kidney morphological changes.
if - workers with " " " .
I range, USA, Europe (see Figure 4:9). .
II » Kobe (From Kitamura, Sumino and Kamatani, 1970).
Ill « Kanazawa (From Ishizaki, Fukushima and Sakamoto, 1970).
IV Tokyo (From Tsuchiya, Seki and Sugita, 1972).
FIGURE 4:10 Cadmium concentrations in renal cortex from
normal human beings in different age groups
(mean values) and exposed workers (single values).
-------
5*7-
42 year female
Cause of death: Gunshot
*»;
^
-fc
onn
fc cUU
QL
£
C ir\rv
O IOO
' «%
|
? e;n
«j 50
c
3
KW
c
1>
^
S?
kj
wound to heod (a) 21 NC
lL_ _.,., fh) CADMIUM
1 (c) MfRfilRY
1 ..t -.- /Q\
-----^ _^ _' "' p (b)
, \
_J l"'
CORTEX _ MEDULLA
i i i i i i i i i i i i i i
234567
Layer Number (from organ surface )
8
FIGURE 4:11
Cadmium, zinc and mercury concentrations
in different layers of the kidney cortex
and medulla (From Livingstone, 1972).
-------
* »^
3.0
2.0
o>
(C
D
c
3 1.0
A
-
.
<
»
{
i *
''N=34
° 10 1
s4
/
/o _ tj
20 J
(N=86
N-125,
>N=101
<
'
'"""*
~
T +JS.D.
. 0 Mean
1 -1S.D.
rN=54
<>N=14
30 40 50 60 70 80
Years of Age
FIGURE 4:12 Average cadmium concentration iri urine
within different age groups in Tokyo
(From Tsuuhiya, Soki and Sugita, 1972a).
-------
Sl-ci
Cadmium in urine
vg/gram creatinine.
40
35
30
25
20
15
10
5
. Normal or glomcrular
proteinuria
* Tubular proleinuria
10
is
20 25
exposure time
In years.
FIGURE 4:13 Relationship between exposure time and
cadmium excretion in urine among workers
in an alkaline battery factory
(From Piscator, 1972).
-------
-*?
r
I
5
50 100
PACK-YEARS
150
O= Cigarette smokers. O ^Non-smokers.
FIGURE 4:14 Cadmium "body burden" (as expressed by
the calculated sum of renal, liver and
lung burdens) in relation to cigarette
smoking (From Lewis et al., 1972).
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-SB-
CHAPTER 5 EFFECTS AND DOSE-RESPONSE RELATIONSHIPS
Just as in the previous review (CITE) the chronic effects on the
kidneys will be given the roost extensive treatment here, since
the kidney is the critical organ and renal tubular dysfunction
is the main feature in chronic cadmium poisoning. Effects
which may be related to renal damage, such as effects on bone,
will also be discussed. Other effects, resulting from both
acute and chronic exposure, were dealt with thoroughly in
CITE and will be taken up more summarily here.
Epidemiological studies on proteinuria associated with cad-
mium exposure in Japan will be referred to in Chapter 6.
5.5 RENAL EFFECTS AND DOSE-RESPONSE RELATIONSHIPS
It is well documented that long-term exposure to cadmium may
give rise to renal damage in both animals and man. A char-
acteristic symptom is proteinuria of the tubular type. Cad-
mium is considered to be transported to the tubules with a
low molecular weight protein, metallothionein and has been
found to accumulate there with a very long biological half-
time. When a level of about 200 ppm is reached in renal cortex,
the first sign of tubular dysfunction (tubular proteinuria)
may appear in sensitive persons. Furthermore, exposure to
cadmium may lead to generalized renal tubular damage with
increased excretion of amino acids, glucose, phosphorus and
calcium. This may eventually cause changes in metabolism with
decalcification and osteomalacia.
5.1.1 In human beings
During the last years only a few new reports have appeared. Goyer
et al., 1972, studied the excretion of amino acids in 10 workers
exposed to cadmium oxide fume in a Japanese factory producing
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-59- .
silver-cadmium alloys. Excretion of cadmium ranged from 7-362
yg/1, meaning that the exposure roust have been heavy in many
cases. No significant differences in the excretion of indiv-
idual amino acids were seen when the workers were compared
to a control group. Specific increases in the excretion of
certain amino acids as reported by Clarkson and Kench, 1956,
were not found.
Piscatpr, 1972, reported on 27 workers exposed to cadmium oxide
dust for 0.5-25 years and generally without proteinuria as judged
by the results of qualitative tests (Trichloracetic acid). (For
details see section 4.3.4.1). It was found that significant
increases in the excretion of 32~microglobulin and changes
in electrophoretic patterns could occur without demonstrable
increases in total urinary protein. It was also shown that
cadmium excretion generally was higher in workers with tubular
proteinuria. Nomiyama, 1971b, also found a higher cadmium
excretion in workers with proteinuria than in those without
it (Trichloracatic acid or Sulfosalicylic acid test).
5.1.2 In animals ',
Several long-term studies have been reported which give further .
information on the mechanism for development of renal damage
and its relationship to tha critical levels in the kidney.
Nordberg and Piscator, 1972, found a decrease in the excretion
of total protein in male mice given subcutaneous injections
of cadmium chloride (0.25 or 0.5 mg Cd/kg body weight 5 days
per week for 6 months). The main urinary protein in male mice
is a low molecular weight protein, synthesized in the liver,
and this synthesis is stimulated by testosterone. A possible
cadmium influence on testosterone synthesis could explain
a decrease in the synthesis rate of that protein, and in turn,
a decrease in total urinary protein excretion. After 21 weeks
of exposure, cadmium excretion increased in mice given 0.5
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-60-
mg/kg. At that time there were also changes in the urinary
protein electrophoretic pattern, which earlier had been
dominated by the above mentioned testosterone dependent pro-
tein. Other proteins appeared which had a pattern indicating
renal damage. Further examinations (Nordberg, unpublished
data) at the end of the experiment, i.e. after 24 weeks
of exposure, showed average concentrations of 170 ppm of
cadmium in whole kidney (Table 4:1) in both exposure groups,
which corresponds to renal cortex levels of about 170-250
(section 4.2.2).
Piscator and Larsson, 1972, gave cadmium in drinking water (0-10
ppm) to groups of female rats on normal and low calcium in/take, '
respectively. The animals were killed after one year. In rats on
calcium deficient diet and drinking water with 10 ppm cadmium, the
cadmium level in renal cortex was about 90 ppm. The total protein
excretion was not significantly increased in these rats compared
to control rats on a calcium deficient diet, but without exposure
to cadmium. There was a highly significant increase in ribonuclease,
which may be in accord with findings in humans with chronic
cadmium poisoning. It may well be that the excretion of ribonu-
clease in the rats was a very early sign of renal tubular dys-
function .
Nishizumi, 1972, gave male rats cadmium in drinking water at
concentrations of 10, 50, and 300 ppm. Animals were killed
after 6, 12, 24 and 40 weeks and the kidneys examined by
electron microscopy. In rats given water containing 10 ppm
cadmium, minor changes were noticed already after 6 to 12
weeks. After 40 weeks slight but obvious changes were seen,
such as swollen mitochondria and vacuoles containing cell
debris. At high dose levels obvious changes were noted already
after 6 to 12 weeks and pronounced mitochondrial changes after
24 to 40 weeks. Cadmium concentrations in organs were not
determined.
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-61- .
Berry, 1972, gave male rats subcutaneous injections of 1.4
mg of cadmium suIfate 3 times a week for 5 months. At this
high dose level (2-3 mg Cd/kg body weight) proteinuria was
said to have appeared after one month (method not stated).
Electron microscopy revealed glomsrular and tubular lesions
after one month.. No determinations of the cadmium content
of the cortex were performed. At the doses given, very severe
renal lesions would be expected.
Ogawa et al., 1972b, reported on an experiment in which mice
were given water containing 146 ppm of cadmium. After three
months a considerable reduction in carbonic anhydrase activity
in blood, liver and kidney was observed.
Stowe, Wilson and Goyer, 1972, gave 10 rabbits cadmium in drinking
water (160 ppm) for 6 months. The mean exposure was 15.5 mg
Cd/kg body weight per day. Assuming that 1-2 percent had
been absorbed, this dose would result in a mean daily absorption
of 0.16-0.32 mg/kg. Cadmium was determined in whole kidney
and histopathological examinations were carried put by light
and electron microscopy. The mean renal concentration was
17,0 (S.D. 14) ppm wet weight. Calculating with a ratio of
1.5 between cortex:whola kidney (section 4.2.2) would give
about 250 ppm wet weight in the cortex. Extensive interstitial
fibrosis was seen by light microscopy in the kidneys of exposed
animals. Pronounced changes were seen in the proximal tubules,
including pyknosis, karyorrhexis and epithelial sloughing.
Electron, microscopy also showed seemingly unaffected mitochon-
dria. Collagen was deposited in the glomeruli. Amyloid deposits
could not be demonstrated. ...:
Castano and Vigliani, 1972, have studied the fate of horseradish
peroxidase (a low molecular weight protein) when intravenously in-
jected into cadmium exposed rats with weights of about. 300 g.
-------
-62-
Cadmium (0.16 mg Cd, 3 times a week for 1-4 weeks) was given
intraperitoneally as cadmium chloride. The results indicated
«
that horseradish peroxidase, after being filtered through
the glomerular membrane, was reabsorbed in a normal way. Elec-
tron microscopy revealed normal pinocytosis. No determinations
of cadmium in the kidneys were performed. An estimate of the
concentration of cadmium in renal cortex can be obtained by
comparison with an experiment by Bonnell, Ross and King,
1960, who gave rats intraperitoneal injections 3 times a week
in doses of 0.75 mg/kg. This dose resulted in an average renal
concentration of about 60 ppm (cortex levels not above 100
ppm wet weight) after one month. Since the dose given by
Castano and Vigliani was 2/3 of that given by Bonnell, Ross
and King, the renal cortex level could be expected to be below
100 ppm.
Regarding the mechanisms for the accumulation and toxic effects
of cadmium in the kidney, a study by Nordberg, 1971a, is of
interest. He gave mice subcutaneously a single dose of cadmium
(1.1 mg/kg) together with metallothionein. Renal tubular damage
resulted while no such effect was seen in another group of
mice given a corresponding dose of cadmium as CdCl_ alone.
It is conceivable that cadmium bound to metallothionein
passed the glomeruli and was reabsorbed into the tubules.
(This experiment is also described in section 4.5). These
acute effects are similar to those described after injection
of cadmium together with cysteine (Gunn, Gould and Anderson,
1968b) or together with BAL (Gilman et al., 1946, Dalhamn
and Friberg, 1955) or EDTA (Friberg, 1956).
5.1.3 Dose-response relationships
In the previous review it was estimated that 200 ppm wet weight
is the critical level in the renal cortex. This is' the level
at which the first signs of tubular dysfunction may appear, in
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sensitive individuals. This estimate was based mainly on data
on kidney concentrations of ca-dmium, determined after death
or after renal biopsy, under most circumstances from workers
exposed to cadmium. In cases with no or slight proteinuria,
and without histological changes, renal cortex levels were
around 200 ppm wet weight or higher. In cases with long standing
proteinuria and morphological renal damage, renal cortex con-
centrations were low, often below 100 ppm wet weight. This
was explained by the fact that whenever renal damage becomes
apparent, large amounts of cadmium are lost, probably due
both to decreased reabsorption of cadmium containing proteins,
and to losses of renal cells. From animal data, which supported
the 200 'ppm estimate, and available data on absorption and
excretion rates in normal human beings, the doses necessary
for reaching the critical level under different conditions
were calculated.
During the last years some new data have been obtained which
have given further information about levels at which renal
dysfunction may occur. Nomiyama, 1971b, describes the findings
on autopsy of one woman and two men (all 3 without occupational
exposure) from the Annaka district where a large zinc smelter
is situated. He also had examined these people prior to their
deaths and the comparative results are seen in Table 5:1.
Nomiyama is of the opinion that the critical level in the
renal cortex cannot be as low as 200 ppm, stating that in
one case he found a level of 260 ppm without renal damage.
The term critical level, as used in the present report, how-
ever, means the level at which sensitive persons may suffer
renal tubular dysfunction. This implies that in a population
one may find many persons with renal cortex levels above 200
ppm but without renal tubular dysfunction. Moreover in the
case described by Nomiyama, no electrophoretic examination
of urinary proteins had been carried out. Slight tubular dys-
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function as characterized by pathological electrophoretic
patterns but with negative qualitative proteinuria tests
may well/exist without any morphological changes in the
kidneys. .
Another of the descriptions by Nomiyama involved a man aged i-
45 who had lived in the same area all his life. In this case
glucosuria and tubular proteinuria were present. The cadmium ;
concentration in renal cortex was very low, only about 24 i
ppm, while the concentration in pancreas was very high, about |
i
20 times higher than normal. This case fits with earlier observation^1
I
of very low cadmium concentrations in renal cortex synchronous.
!
with severe renal damage despite high concentrations in liver
". ' ' ' -i
and pancreas.
The studies by IMordberg, 1971a, (see sections 4.2.2 and
5.1.2} give additional evidence that the critical level is
about 200 ppm. In one group of mice given 0.25 mg Cd/kg body
weight, 5 days a week, ihenal tubular damage was not found
after 24 weeks of exposure, whereas in a group given 0.5
mg Cd/kg body weight, 5 days a week, renal tubular dysfunction
was apparent after 21 weeks of exposure. Both groups were
killed 24 weeks after the beginning of the exposure and in
both groups renal levels of cadmium were about 170 ppm, cor-
responding to cortex levels ^of 170-260 ppm wet weight. Liver
levels were about the same in both groups, whereas levels
in other organs (Figure 4:1) were about twice as high in the
group which .had received the higher concentration of cadmium.
It may be remembered that the study by Stowe, Wilson and
Goyer, 1972, also Supported a critical level of about 200
ppm in kidney cortex.
As has been mentioned earlier in this chapter, Piscator and
Larsson, 1972, studied the excretion of ribonuclease in rats
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exposed to cadmium in drinking water. In rats on a calcium
deficient diet, an increased excretion pf ribonuclease was
found at renal cortex levels of about 90 ppm, indicating a
considerably lower critical level than the one estimated
in earlier investigations covered in CITE. Estimates of critical
level were based on results obtained by relatively crude
methods and it waa suggested that cellular effects may well
appear at lower levels. Furthermore, the rats in Piscator >
and Larsson's studies were severely deficient in calcium,
a condition not uncommon in large populations in several areas
of the world. '
i
5.2 EFFECTS ON BONE
In CITE it was shown that exposure to cadmium in calcium deficient
rats would cause a rapid demineralization (Larsson and Piscator,
1971). Further analysis of the data showed that calcium deficiency
gave rise to a compensatory increase in the parathyroid volume.
If the animals were exposed to cadmium, such an increase in
parathyroid volumes did not occur. New experiments (Piscator
and Larsson, 1972) revealed an increase in excretion of ribo-
nuclease in female rats after one year of exposure to 10 ppm j
of cadmium in drinking water and a diet low in calcium. This |
finding indicates renal tubular damage. There was also a significant
reduction in the mineral content of bone. Whether the bone j
changes were due to the changes in renal function or due to i
an effect of cadmium on intestinal absorption of calcium is
not known.
i
More evidence that exposure to cadmium may cause bone changes :
in animals comes from Hirota, 1971. He exposed rabbits for i
about one year to cadmium in water corresponding to daily .,;
doses of 5 and 20 mg Cd per rabbit. The rabbits exposed to
i
20 mg Cd/day showed histological signs of renal tubular changes i
at the end of the exposure. X-rays of femur caused him to
suspect osteomalacia and osteoporosis. An increase in serum
-------
X
N
-66-
calcium and decrease in serum phosphorus as well as an increase
in the urinary excretion of calcium and phosphorus were also
seen. Proteinuria was noted in some animals.
5.3. EFFECTS ON THE LIVER
In CITE it was concluded that liver dysfunction is not common
in workers exposed to cadmium. Animal experiments indicate
that certain enzyme activities may be influenced at cadmium
levels in the range found in normal human adults.
A recent investigation on rabbits by Stowe, Wilson and Goyer,
1972, gives additional information. The experimental conditions
have been described in sections 4.2.2 and 5.1.2. After 6 months
of oral exposure to cadmium, mean liver concentrations were 188
ppm wet weight. Light microscopy revealed that in contrast
to controls the cadmium exposed rabbits showed depletion of
glycogen and deposits of collagen. Inflammatory cell infiltrates
were frequent in the portal regions and biliary hyperplasia
was often present. Electron microscopy revealed that the most
striking changes took place in the endoplasmic reticulum,
which was increased in exposed animals.
Liver function tests, such as determination of activity of
GOT, GPT, alkaline phosphatase and LDH isoenzymes in serum,
BSP-test and blood coagulation tests did not show any difference
between controls and exposed. These results indicate that
negative liver function tests do not exclude morphological
liver changes.
5.4 OTHER EFFECTS
Pond and Walker, 1972, showed that a single prophylactic in-
jection of iron can prevent the occurrence of cadmium anemia
in growing rats exposed for 4 weeks to 100 ppm of cadmium
in the diet. Addition of iron to the food had the same preven-
tive effect. Fox et al., 1971, studied Japanese quail fed
a diet containing 75 ppm of cadmium. In addition to iron.
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-67-
ciscorbic acid prevented anemia. According to the authors ascorbic
acid was a good prophylactic because it brought about increased
absorption of iron from the intestinal tract. Weber and Raid,
1971, reported that ascorbic acid partially reduced the
toxicity of cadmium in chicks.
Schroeder and Mitchener, 1971, looked for teratogenic and re-
productory effects of cadmium. Mice were exposed during two
generations to cadmium in drinking water (10 ppm) from the
end of the weaning, period until the end of the experiment.
Cadmium was found toxic for breeding mice to such an extent
that the strain did not survive beyond the second generation.
Congenital abnormalities appeared at a much higher frequency
than in controls. Cadmium and zinc were not determined in
organs. Since cadmium does not transverse the placenta,
it is conceivable that a teratogenic effect would be due to
a secondary zinc deficiency in the fetuses. The mothers retain
more zinc during exposure to cadmium, leaving less zinc available
for the fetuses. During exposure to cadmium, more zinc than
normal is stored in liver and kidneys and less in testes . (Petering,
Johnson and Stammer, 1971). The only data available on humans
in this context are those already taken up in CITE, showing,
in short, a significantly decreased weight in newborns of cadmium
exposed women (Cvetkova, 1970).
Biochemical affects of cadmium, especially with regard to
affects on enzymes, have recently been treated in an extensive
review by Vallee and Ulmer, 1972.
5.5 CONCLUSIONS
Animal studies have verified that cadmium exposure may cause
renal tubular damage. This damage occurs at cadmium levels
of about 200 ppm wet weight in renal cortex, which is in
accordance with the earlier estimate of 200 ppm as the crit-
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ical level in the cortex. In calcium-deficient animals exposed
to cadmium, urine studies indicate that this level may be
even lower under certain circumstances.
Investigations on animals and on workers exposed to cadmium
have further strengthened the earlier statement that the excre-
tion of cadmium will increase .when tubular dysfunction appears.
Severe morphological changes may be found in the liver of animals
even though common clinical tests for liver function are normal.
Further studies of the effects of. cadmium on bone have shown
that in animals cadmium exposure may cause demineralization. .
In calcium-deficient animals this process will be accelerated
by cadmium. An influence on the parathyroids has been found.
-------
TABLE 5:1 Results of examination before and after deatti of three
persons from Annaka. (From data by Nomiyama, 1971b).
Case
designation
number
Age .45
Sex M
Estimated intake
of cadmium 211 (1969)
Liver Cd, ppm
wet weight 35
Renal cortex Cd,
ppm wet weight 29
Pancreas Cd, ppm
wet weight 41
Cd yg/1
urine 5-24
Urine protein +
Glucose +
Morphological *
changes +
57
M
350 (1969)
32
264
24
.6-25 . . .
'
N.D.
_ XX
84
F
Not known
29
134
18
N.D.
N.D.'.
N.D.
+
Examination by electrophoresis and gel filtration revealed that
the proteinuria was of a tubular type.
X X
In the reoort it is stated "only such a change as tangle of renal
tubule cells was observed".
.N.D. = Not detectable
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CHAPTER 6 EPIDEMIOLOGICAL INVESTIGATIONS IN CADMIUM-
POLLUTED AREAS OF JAPAN
6.1 INTRODUCTION
In our previous rsview Cadmium in the Environment (CITE) it was
seen that the prevalence of proteinuria and glucosuria in older age
groups was higher in the cadmium polluted Itai-itai disease
district, Fuchu, in Toyama Prefecture, than in an unpolluted
non-endemic district (Figure 6:1). This difference in prevalences
was concluded to be related to cadmium exposure. Another cadmium
polluted district, which was presented in CITE and compared to
a control area was a part of Tsushima in Nagasaki Prefecture.
Proteinuria among older age groups was more common in the polluted
than in the control area (Figure 6:2).
Other areas of Japan were under study for the effects of cadmium
pollution. Based on cadmium concentrations in rice and soybean
paste ("miso") it could be ascertained that in some of these
other areas cadmium exposure was considerably higher than in
control areas. As cadmium is used extensively in mining, smelting
and other industrial operations throughout Japan, it was inferred
that the cadmium problem may well be far-reaching.
In order to map the extent of possible effects of cadmium the
Japanese Ministry of Health and Welfare and the authorities
of the prefectures concerned have during the last years made
a number of epidemiological studies in at least 13 areas suspected
for cadmium pollution.
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-70-
Data on daily cadmium intake are scarce. However, cadmium
concentrations in rice are usually available due to the
fact that the Ministry of Health and Welfare has ordained
that in the areas suspected for. cadmium pollution yearly analysis
of cadmium in rice should be undertaken.
Past changes in daily intake are important for evaluating
possible effects (Kjellstrom and Friberg, 1972] but as there
are generally no data on past cadmium concentrations in rice, '
possible changes often 'have had to be inferred from production j
changes at' -the cadmium source. '
Most of the data on medical effects presented below co.ncern ;
proteinuria. Of all possible indicators of an effect, proteinuria
is the only one which' has been measured and reported on consistently,,
though the methods for analyzing it vary. .
Available data which have been considered of interest for
discussing dose-response relationships have been included.
The data have been collected through personal visits to Japan,
from published articles and from a large number of internal
mimeographed reports and unpublished data. In Figure 6:3 the '
places which will-be mentioned in this report can be found.
6.2 METHODOLOGY '
Much of the medical data used in this report have resulted
from health screenings in the polluted areas. These have generally ;
been performed according 'to standard methods recommended by
the Ministry of Health and Welfare and these methods will
be described briefly in this section. Methods fo.r estimating
daily intake are also presented and discussed. .
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-71-
6.2.1 Method for selection of areas studied for cadmium-pollution
The Ministry of Health and Welfare, 1969, published a standard
method for selection of "areas requiring observation for
cadmium-pollution". If within a village values of cadmium
concentration in drinking or irrigation water higher than
0.01 ppm or values in unpolished rice higher than 0.4 ppm
are found, urine samples from 30 randomly selected adult
persons from the village should be collected. The samples
are mixed and if the cadmium concentration in this mixed sample
is more than 9 yg/1, or if the average daily cadmium intake
in the village can be calculated to be more than 300 y.g, the
village should be designated as an "area requiring observation".
In most polluted districts a large number of villages is included
in the "area requiring observation".
It should be pointed out that in some of the areas discussed
in section 6.3 (e.g. Annaka) cadmium concentrations in rice
over 0.4 ppm have been recorded outside the "polluted area". In
large parts of the "polluted area" in Bandai cadmium concentrations
in rice do not exceed 0.4 ppm, according to recorded values.
6.2.2 Standard methods for screening of cadmium-related disease
According to the Ministry of Health and Welfare, 1972 two types
of health screening have been used. The old type of health
screening (used until 1971) was divided into two principal
stages. The first stage was a general screening of the population
over 30 years of age in defined areas. Included in the first
screening were: Interview, proteinuria analysis (Trichloracetic
acid), glucosuria analysis (testtape) and blood pressure measurement.
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-72-
All persons who were confirmed as h'aving proteinuria according
to the first screening should continue' to the second screening.
This rule of the standard method has not been strictly kept
in all areas, which is obvious when going through the listings
of the individual results (Japanese Association of Public Health,
1970a). The difference between the number with proteinuria
and the number studied in the second screening is less than
10 percent in all cases that have been possible to check.
In the second screening a more detailed study on blood and
urine was performed and the results of this study were used
for evaluating if a person had any effects of cadmium, exposure.
In May, 1971, the Ministry of Health and Welfare published
a new standard method for screening cadmium-related disease
(Ministry of Health and Welfare, 1971b). The target population
should be persons over 30 years of age. For qualitative proteinuria
measurements the Trichloracetic acid method or the Sulfosalicylic
acid method or both were recommended. In this new standard
method cadmium concentration 'in urine should be measured in
the first screening. Glucosuria measurement was moved to the
second screening, where also measurement of proteinuria (any
quantitative method' could be used, but should be clearly described)
and cadmium in urine as well as disc electrqphoresis of urinary
proteins were to be performed.
If the disc electrophoretic pattern showed tubular damage at
the second screening a third and final screening should be
performed. It included a number of blood and urine tests as
well as X-ray of certain bones. A distinction was made between
those who had a cadmium concentration in urine over 30 yg/1 and
those who had under 30 y,g/l. This level was referred to in
Japanese Association of Public Health, 1970b, as a lower
limit for pathological cadmiumuria.
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- 73-
The result.of the third screening should be analyzed in the
following way: The study group for differential diagnosis of
cadmium poisoning and Itai-itai disease set up by the Japanese
Association of Public Health discusses the results of all persons
who undergo the third screening and a final conclusion is made.
As noted here the screening .procedures are aimed at finding
suspected cases of Itai-itai disease. As the screenings do not
primarily aim at detecting the prevalence of proteinuria,. tha
urine sample collection methods as well as analysis methods
and classification methods of proteinuria are not uniform from
district to district and in some cases not even within districts.
6.2.3 Standard method for qualitative measurement of proteinuria
(Ministry of Health and Welfare, 1971b)
Either one of methods a) or b) may be used. It is preferable
to combine them.
a) Trichloracetic acid (TCA) method
To 5 ml urine 5 ml of TCA-solution is added (concentration =
35 g/dl).
Foaming should be avoided when mixing and the mixture is
heated to 37°C for 10 minutes.
b) Sulfosalicylic acid (SA) method
3 ml urine samples are put into two test tubes of equal
size. In one of the tubes a solution of sulfosalicylic acid
(20 g/dl) is added drop-wise. The other tube is used as con-
trol for evaluation.
Evaluation: same in both a) and b).
Transparent = - ; Faint white cloudiness = - ; white cloudiness
= + ; Strong white cloudiness = ++ ; milk-colored cloudiness
= +++ ; precipitate = ++++ . In the final reports proteinuria
has usually only been classified as positive and negative.
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- 74 -
in some cases using + or higher as the criterium and in other
+ . ' ' '
cases. - or higher. Another drawback of most of the epidemiological
studies on proteinuria is that the analyses are not made on
a "blind" basis. The persons who'made the analyses knew whether
the urine sample to be analyzed was from an "exposed" area
or a "control" area. When studying proteinuria with methods
relying on subjective evaluations, obvi-ous possibilities for
systematic errors exist if the studies are not made on a blind
basis.
6.2.4 Comparisons of. proteinuria methods
A study in which proteinuria methods have been systematically com-
pared is the one by Fukuyama, Shiroishi and Kubota, 1971. They
compared the Trichloracetic' acid,- Sulfosalicylic 'acid and G-
25 gel filtration methods with disc electrophoresis of urine.
The studies were made on a blind basis (Kubota, personal communi-
cation ).
In the G-25 method (Fukuyama and Kubota, 1970), urine samples
are eluated (20 ml/h in phosphate buffer) on a Sephadex G-
25 column (300 x 9 mm) and 2 ml fractions are collected. Folin-
Lowry reagent is added to each fraction and the absorbance
at 75C nm is measured. An elution pattern of Folin-Lowry positive
substance is achieved and usually three peaks (P, 0, and R)
are found, the first of which has been found to consist mainly
of proteins (Fukuyama and Kubota, 1970). The G-25 protein quotient
is calculated as P/(P+Q + R) . The G-25 gel''filtration method
is rated as + if the G-25 protein quotient is higher than 15
percent, - if the quotient is 10-14.9 percent and - if the
quotient is less than 10 percent (Fukuyama, Shiroishi and Kubota,
1971).
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- 75 -
In Table 6:1 results from a polluted area in Toyama and a control
area are compared. In the polluted district the prevalences
of proteinuria rated as + according to Sulfosalicylic acid
method and Trichloracetic acid method, respectively are 12.7%
and 7.9% and considerably higher (38.2%) with the G-25 method.
On the other hand, in the control district the prevalences
of proteinuria according to the Sulfosalicylic acid method,
Trichloracetic acid method and G-25 method were 1.3%, 2.2%
and 1.3% respectively. Data on spec. grav. are not given, which
would have been of value when interpreting the results. The
G-25 method is not dependant on spec, grav., whereas the result
of acid tests will be dependant on the degree on the concentration
of urine. It is conceivable that there are cases with decreased
concentrating ability in the polluted area.
Fukuyama, Shiroishi and Kubota, 1971, also studied the urines
of the persons from the Itai-itai district with the disc electro"
phoresis method, where 'disc rated + means that the pattern
of the electrophoresis is of the tubular type. As can be seen
in Table 6:2 about one third (30.3%) of those studied had tubular
proteinuria.. Among those who had a rating of at least - according
to the Sulfosalicylic acid method or the Trichloracetic acid
method, or had + in the G-25 method, about 70-80% were tubular
proteinurias. Out of the 50 persons with disc +, 47 also were
positive with the G-25 method. 25 persons resp. 33 persons
were positive when using the Trichloracetic acid method resp.
Sulfosalicylic acid method.
Another study in which two proteinuria methods have been compared
is the one by Kakinuma et al., 1971. 2436 persons from Annaka
were studied with both the Trichloracetic acid method and
the Sulfosalicylic acid method. A good correlation between
-------
/ D
the two methods was found (Table 6:3). One of the methods for
calculating prevalence of proteinuria. (+ or higher) in an area .
will give about 10% lower figures than, if .both .methods a.re
used (+ or higher in either of them). When setting the limit
for proteinuria at + or higher a combined use of both methods
will give 10% higher figures than the Trichlora^etic. acid method
alone and less than 1% higher figures than the Sulfosalicylic
acid method alone (Table 6:3). . . ;
If in two studies on the same population the evaluation criteria
would be so different that all. persons in the i group of one
study would be included in the + group ..of the other study, .
the recorded prevalence of proteinuria as defined.by ratings
of + or higher would be about twice as high in the latter study
.as in the first study. , .
i
6.2.5 Methods for .estimating daily intake . '
' i
Cadmium concentration in rice will have to be used as an indicator
of daily intake when no other data are: available, which is
common. In 4 areas National Nutrition Census (Japanese Association j
i
of Public Health, 1970b) and Total Diet Collection (Japanese i
Association of Public Health, 1970b) have been used. Yamagata
et al., 1971, have used a Standard .Diet method. In some cases
an estimation based on rice only (R.ice-method) has also been
used. ' , , .
i
The National Nutrition Census method (Japanese.Association
!
of Public Health, 1970b) is based on data on average daily
intake of food divided into 22 different groups and the average
cadmium concentration in each food group. A questionnaire is
sent to a sample of families in the po.lluted. and the control
areas. They are instructed to record the amount of each of
22 food groups consumed in the family, for. three days. It was
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- 77 -
not defined exactly (Japanese Association of Public Health,
1970b) how the families are to be selected. Using figures on
the relative calorie requirements in different age groups the
family food intake data were adjusted to an "average adult"
in the area. Samples of the different food groups were collected
from some families included in the questionnaire survey. The
collection procedure was systematized only for stored rice
and "miso" soybean paste. Cadmium concentrations in the food
samples were analyzed with atomic absorption spectrophotometry.
In the control areas samples of only a few food groups were
collected and the calculation of daily cadmium intake was
mainly based on assumed values.
The Total Diet collection method (Japanese Association of Public
Health, 1970b) requires that the persons participating put
a "twin" sample of each foodstuffs they eat during one day
in a container. The material in the container is homogenized
and cadmium concentration is analyzed with atomic absorption
spectrophotometry.
The Standard Diet method (Yamagata et al., 1971) bases the
daily cadmium intake calculation on a specific standard menu
i
recommended by the National Institute of Nutrition. Samples
of seven major food groups included in the menu were collected
from the area to be studied and analyzed for cadmium concentration. |
i
The daily intake was then calculated by multiplying the standard i
amount of every food, group with the measured cadmium concentration.
The Rice-method is an estimation of daily intake based on
the assumption that on the average half the daily cadmium intake
comes via rice. In the studies by the Japanese Association
of Public Health, 1970b 17-83% of the calculated daily intake
came via rice. The daily intake of rice is assumed to be
300 g (Association of Health Statistics, 1972).
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- 7.6 -
The variation in estimated .daily intake within 'an area, as
i
indicated by the range, is a crucial factor when assessing :
dose-response relationships. The individual 'intakes in polluted j
and control areas overlap in Uguisuzawa and Tsushima (Table 6:4] j
and there is a 2-fold to 10-fold increase in intake between '
minimum and maximum value. Dose-response analysis based' on |
daily intakes estimated with National Nutrition "Census (»NNC)
or Total Diet Collection ("TOO will therefore be very approximative
The quotient between intake'in a polluted and.corresponding
i
control area differs depending on the method used. In Annaka
the quotients according to the NNC resp. TDC methods are
2 resp. 3 (Table 6:4) but cadmium concentration in rice in j
the control area was as high as three forths of the concentration |
in the control area.. This discrepancy can partly'be explained
by differences in calculated intakes of certain foodstuffs. '
For example, daily rice intake far-an adult' in most of the j
areas mentioned in Table 6:4 is 350 g - 400 g. In the polluted' '
area of Annaka, though, the intake is only 26,7 g and in the
corresponding control area 281 g. The difference in tha -results ;
of the NNC method depends on differences of cadmium intake :
via wheat and vegetables. The relation between the concentration :
of cadmium in rice and in other fo.odstuffs such as wheat, sweet i
potatoe, vegetables etc., varied greatly. In the polluted area
of Kiyokawa sweet potatoe and wheat had three times higher '
cadmium concentrations, than rice (Japanese. Association of. Public
Health, 1970b), but on the other hand, in the polluted area i
of Tsushima the rice concentration was- 4 times higher than j
that of wheat and 1.5 times higher tha.n that of sweet potatoe.
The geographical features and. agricultural . methods of the polluted
area may explain .such great differences. .' |
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- 79 -
A way to validate the methods would be to study daily fecal
excretion of cadmium as discussed in section 3.2, A comment
that also should be made is that the daily intakes calculated
for some of the control areas (Table 6:4) are considerably :
higher than the estimated average for non-polluted areas of '
Japan, 60 jig/day (Ministry of Health and Welfare, 1969). In '.
the control area of Annaka this is reflected by a very high
concentration in rice, 0.3 ppm.
i
6.3 CADMIUM EXPOSURE AND MEDICAL EFFECTS IN INDIVIDUAL AREAS [
i
6.3.1 Fuchu in Toyama prefecture i
i
In this area Itai-itai disease was first found. The rice fields were i
irrigated from the Jintsu river, which had been contaminated ;
by waste products of the Kami.oka mine.. Ishizaki, 1969, as quoted
in CITE, found that proteinuria and glucosuria were more common
in the Itai-itai disease enflemic area than in a control area
(Figure 6:1). Further epidemiological studies in Fuchu have
been performed (Fukuyama and Kubota, 1972a, b and c) on the
relation between the level of heavy metal pollution and proteinuria j
respectively glucosuria.
Paddy soil from a number of places within the Itai-itai disease
endemic area was analyzed for the content of heavy metals by
a Research Committee for the Itai-itai disease in 1968 according
to Fukuyama and Kubota, 19.72c. They used these values for estimating
exposure levels of Cd, Pb and Zn in 12 villages along 4 different
irrigation canals (Figure 6:4). The villages here mentioned
are in some cases a combination of two to three hamlets, where
populations were small. The concentrations of lead in the soil
are about 100 times higher than the concentrations of cadmium
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- ao -
(Figure 6:6]. On'the other hand, Tsuchiya, 1969, reported
about rice samples from the Itai-itai disease endemic.area
average values of lead concentration about 0.2 ppm and cadmium
concentration about Q.8 ppm.
Ishizaki, Fukushima and Sakamoto, 1968, analyzed the cadmium
concentration, in rice from the Fuchu area (Figure 6:5). In
rice from paddies irrigated by the Jints'u river values over
2 ppm were recorded and in the most polluted district values
under 0.5 ppm were very uncommon.
Fukuyama and Kubota, 1972c, examined women over 40 years of
age (79.7% participation of the women living in the villages).
As shown'in Figure 6:6 proteinuria (Sulfosalicylic acid method)
and glucosuria (Testtape) were well correlated to metal concentra-
tions in soil. These analyses were performed on a blind basis
(Kubota, personal communication). Itai-itai disease patients
had an excretion of lead in urine Within normal ranges (Tsuchiya,
1969).
In another study an undefined target population of men and
women (Fukuyama and Kubota, 1972b) was examined with the G-
25 gel filtration method and disc electrophoresis (blind study
according to Kubota, personal communication). This time the
villages were divided into three groups with different levels
of metal concentration in soil.Tubular patterns in disc electro"
phoresis (disc >)--were more common among the persons with longer
exposure time and higher age. Given the same exposure time,
such patterns were more common among persons living in high-
exposure areas (Fukuyama and Kubota, 1972b). From the data
it can also be calculated that the G-25 protein quotient increases
with exposure time (living time i-n the area) (Table 6:5) and
with exposure level (pollution level) for those older than
40 years.
-------
Shiroishi, Tanii and Kubota, 1972 studied proteinuria in
161 persons (aged 6-61 years) from a non-polluted area
of Toyama Prefecture (0-area) and 105 persons (aged 59-
92 years) from a home for the aged in Toyama city. Proteinuria
was measured quantitatively .with the Kingsbury-Clark method
and also disc electrophoresis was performed. The persons
from 0-area were divided into two groups according to age,
over and under 60 years. The distribution of different
protein concentration levels in urine is shown in Figure
6:7. A protein concentration over 10 mg/dl occurs in about
5% of both the older and younger persons from Q-area but
in 20% of the persons from the home for the aged. In Table
6:6 is shown the prevalence of different patterns on disc
electrophoresis. Among the young group from 0-area 95%
have normal patterns as compared with 87-89% in the other
groups. About 7% have glomerular patterns both among the
old in 0-area and those from the home for the aged in Toyama.
2% Itai-itai patterns are found in this latter group, but
none in the other two groups. These data indicate that
disc electrophoresis patterns of the tubular type (Itai-
itai-type) are uncommon among "normal" elderly people in
Japan. It was not mentioned whether or not the study was
performed on a blind basis.
The average daily cadmium intake was not calculated in
the recent epidemiological studies in Fuchu. The effects
of cadmium exposure can therefore only be assessed qualitatively
higher exposure gives higher frequency of tubular proteinuria
and glucosuria. Since ttl& analyses were carried out blindly
the studies by Fukuyama and Kubota mentioned in this section,
have an advantage over most other recent Japanese epidemiological
studies on the effects of cadmium.
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- 82 -
6.3.2 Tsushima in Nagasaki Prefecture
Four villages with a total population of about 1000 are
spread along two rivers polluted with cadmium and other
heavy metals from mining operations (Figure 6:8]. The mines
in the area were started in 674 but large-scale production
did not start before World War II. The volume of zinc production
increased from 1,000 tons in 1948 to 21,000 tons in 1958
and has been relatively stable (22',000-29,000 tons) since
then (Terada, pers. comm.).
In CITE an epidemiological investigation from 1969 was
presented in detail. Similar investigations have .been performed
> ".;'.- -.,:'-' .,:'< ::; -:>. : f :<': v' .'/' "-i, .<,>.*..'' :..\j'.'-';'- -'J.-y, "^-~. ':::'.'.>: . /-V-!"' /';,-'>'; <".: - '.'; >. '.'.'
in 1970, 1971 and 1972V Unfortunately',' the method's'fuse'd 1>ir- '
and the presentation of results are not the same in the
different studies. Only parts of the control area used
in 1969 have been studied in the later studies and in 1972
no control areas at all were studied according to the report
available to us (Nagasaki prefecture, 1972 a).
According to 5 different studies the rice levels of cadmium
are at least 6 times higher in the polluted areas (Kashine,
Shimobaru, Komoda, Shiine) than in the control.area (Are)
(Table 6:7). The average daily cadmium intake for adults
has been calculated (Japanese Association of Public Health,
1970 b) with the National Nutritional Census method to
be 215 yg in the polluted villages and 59 yg in the control
village Are (Table 6:4). The Total Diet method .on a sample
of 8 persons from each of the polluted area and the control
area gave 213 yg resp. 104 yg.
-------
Tha study from 1969 quoted in CITE showed that the prevalence
of proteinuria (Testtape) (Takabatake, pars. comm.) was higher
in polluted villages than in control villages (Are and .Hikage-
kamiyama) (Figure 6:2). In 1970 547 persons over 30 years
of age from the polluted area (participation 43% of the target
population) and 120 persons from a control village (Hikage-
kamiyama) (participation 27%) were studied (Nagasaki Prefec-
ture, 1971). The reported prevalence of proteinuria (Trichlor-
acetic acid method + or higher, according to Terada, pers.
comm.) was 4.9% and 0.8% respectively. The difference was
statistically significant.
In 1971 882 persons in the same age groups were examined in
the polluted area (participation = 81%) and 5.3% had proteinuria
(Nagasaki Prefecture, 1972 b). In the control area (Hikage-
kamiyama) 177 were examined (participation = 43%) and 4.5%
had proteinuria (Trichloracetic acid method) (Nagasaki Prefecture,
1972 b). The studies in Tsushima have not been carried out
on a blind basis (Terada, pers. comm.).
Age-related proteinuria prevalences have been reported by
Terada, pers. comm. The data generally show an increase in
proteinuria with age. The control groups studied are very
small. No significant differences between control and polluted
areas within 10-years age groups can be found. The situation
in Tsushima is difficult to evaluate due to inconsistencies
in methods used and the low participation.
6.3.3 Ikuno area of Hyogo prefecture
The source of cadmium in this area is a copper and zinc mine,
which dates back to 807 and which has had a fairly constant
production during the last decades. The first epidemiological
study was performed in 1971 on 1676 persons over 30 years
of age living in a number of villages along the Ichikawa river
(Watanabe, pers. comm.). The aim of the study was to find
suspected cases of Itai-itai disease. In 1972 the same area
was studied once more regarding proteinuria (Hyogo Prefecture,
1972).
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-84-
In February 19/1 cadmium pollution was detected in this area.
Average cadmium concentration in rice produced in 1970 and
1971 was studied by the agricultural bureau of Hyogo Prefecture
x)
(according to Ikuno Mining Poll., 1972). The average cadmium
concentration in 214 samples of rice from 1970 was 0.50 ppm
and in 150 samples from 1971 0.39 ppm. The concentrations
of cadmium in rice at various places along the Ichikawa river
were mapped (Figure 6:9), although it was not mentioned in
the report just how the samples were chosen..The figures along
the river are average values within different towns along
the river as reported by Ikuno Mining Poll., 1972 (see Table
6:8). We have no detailed data from Hyogo Prefecture, but
the magnitude is in accord with data from Watanabe (pers.
comm.). . .
In Ikuno no studies on daily cadmium intake have been performed.
Based on the rice method (see section 6'.2.5) it can be calculated
that in Ikuno town (I) the average daily intake would be around
420 yg(Cd in rice =. 0.69 ppm) and in Kamisaki (K) town 290
yg (Cd in rice = 0.48 ppm).
The "polluted" area in the. 1971 epidemiological study (Watanabe,
pers. comm.) was selected according to the standard method
(see section 6.2.1). A number of villages, where average cadmium
concentration in urine of inhabitants was more than 9 pg/1,
were designated as the area requiring health examinations..
1676 of the 1700 persons over 30 years of age living in these
villages were examined in 1971 with a modified first screening
for Itai-itai disease (cf. section 6.2.2) consisting of interviews,
measurement of blood pressure and proteinuria (Trichloracetic
acid method). 21.9% of those examined had proteinuria (+ or
higher). No data from a control area ware reported.
This reference was published by the "Ikuno Mining Pollution
Prevention Professional Group",, which is an anti-pollution
citizen group. Efforts'are being made to verify the exposure
data directly by Hyogo/ Prefecture and indirectly by Dr. Tsuchiya.
-------
A new epidemiological study on the same target population
was performed in 1972 (Watanabe, pers. comm.). This time 3
control areas were also examined. According to Watanabe (pers.
comm.) cadmium concentration in rice in the control area A
("Kaibara") was considered to be less than 0.1 ppm. The
epidemiological study of 1972 was performed by the Hyogo Prefecture
Committee for the study of cadmium poisoning, of which Professor
Kitamura is chairman. The Committee's accumulation of data
was presented to the study group for differential diagnosis
of cadmium poisoning and Itai-itai disease on September 6,
1972 by Dr. Watanabe. The method used for proteinuria analysis
in 1972 was the Sulfosalicylic acid method and the results
are shown in Table 6:9 (Hyogo Prefecture, 1972). The polluted
area (Ikuno) has a strikingly higher prevalence of proteinuria
than two of the control areas and the prevalence is also considerably
higher than in the third area. The studies were not carried
out blind. On the other hand the magnitude of the difference
is such that it seems difficult to explain the differences
between polluted area and control area by methodological factors.
In order to evaluate the differences in prevalence of protein'-
uria Watanabe studied a random sample of 376 persons from
Ikuno and 250 persons from "Kaibara". In these samples prsvalencs
of proteinuria (Trichloracetic acid method) was 18% resp.
12%. The results of Sulfosalicylic acid method in the whole
population were about 3 times as high. As the methods should
give fairly similar results (see section 6.2.4) there is reason
to believe that the samples were not representative of the
whole population as far as proteinuria is concerned. The geometrical
average protein concentration in urine (Biuret method) was
2.19 ug/dl (exposed) resp. 2.42 yg/dl (control)(Hyogo Prefecture,
1972). In the sample a lot of normal urines were included,
which has a strong influence on the geometrical average. Similar
studies were not carried out in the two control areas with
lower prevalence of proteinuria.
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-66-
Tha high prevalence of proteinuria in Ikuno has been confirmed
by Ishizaki et al., 1972. He studied 18 persons over 50
years of age (all farmers, both sexes, who had lived more
than 30 years in the area) from Mayumi (Figure 6:9), one
of the most polluted villages. 56% had proteinuria (sulfosalicylic
acid method) and 39% concurrent proteinuria and glucosuria
(testtape).
Watanabe et al., 1972, have shown that the globulin/albumin
ratio is commonly elevated among'persons with high cadmium
exposure and with high protein- and cadmium concentrations
in urine. Elevated globulin/albumin ratio reflects tubular
proteinuria and is suggested by Watanabe et al., 1972 as
an index for screening of cadmium induced proteinuria. Such
studies have been carried out by Watanabe in areas with
different degree of cadmium pollution.
For 6 villages with different levels of cadmium exposure
data on urinary cadmium and globulin'/albumin ratio have been
compiled (Watanabe, unpublished) (Table 6:10). The age distri-
bution of the persons sampled was not reported. There was a
significant difference.: in globulin/albumin ratio between
persons living in villages with 0.33-0.35 ppm average cadmium
concentration in rice and those with 0.61-1.10 ppm. Urinary
cadmium concentrations increased distinctly wi.th increasing
cadmium in rice. . ' ,,
6.3.4 Kakehashi area in Ishikawa prefecture .
The source of.cadmium in this.area is nowadays the Hokuriku
mine and was earlier also the Ogoya mine (Figure 6:10) .
An epidemiological study has been performed by Ishizaki,
1972. A total of 209 persons over 50 years- of age from four
villages were studied for proteinuria, glucosuria and cadmium
in urine. No non-polluted area was included. Results of the
study together with cadmium concentrations in rice are given
in Table 6:11.
The village Kanahira closest to the mine, is the most polluted
with an average cadmium concentration in rice of 0.80 oom
-------
-87-
(Table 6:11). In the other villages the concentrations were
between 0.23 and 0.34 ppm. Average urinary cadmium concentration
was 23.3 yg/1 in the most polluted village. Urinary cadmium
concentrations were also high in the other villages. Prevalence
of proteinuria (3% Sulfosalicylie acid method) was 39% in
the most polluted village and 22-30 % in the other villages.
Ishizaki, 1972, considers positive reaction with this method
to occur at 5 mg protein/dl urine. It is not clear how this
evaluation was made. Concurrent proteinuria and glucosuria was
twice as high in the most polluted.village as in the other
villages.
Urine protein electrophoresis on cellulose acetate membrane
was performed in several cases. The results of these examinations
are shown in Figure 6:11. Tubular proteinuria was a common
finding and clearly pathologic electrophoresis patterns were
almost always of the tubular type. Ishizaki, 1972, concluded
that the findings in Kanahira village are similar to those
in the Itai-itai district, even though he did not find signs
of actual Itai-itai disease. He considered that signs of
cadmium effects had been shown in the other three villages
as well.
6.3.5 Bandai area in Fukushima Prefecture
Bandai town in Fukushima Prefecture has been polluted by
cadmium via air and sewage water outlets from a zinc refinery.
An epidemiological survey according to the old standard method
was performed in 1970. On those who did not undertake the
screening in 1970, follow-up studies were performed in 1971
and 1972, but since very small groups ware included the results
are not discussed here.
The refining of zinc was started in this town in 1916 and
lead production in 1940. At present also cadmium and other
substances are produced. In 1962 zinc production was 2,200
tons per month (Nisso Smelting Co., 1972) in 1965 2,500 tons
per month and in 1970 4,000 tons per month (Fukushima Prefecture,
1972).
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-86-
Cadmiurn concentration in unpolished rice from 1970 and 1971
within the polluted area varies between lower than 0.2 ppm
v
to higher than 1.0 ppm (Fukushima Prefecture, 1971. a).
The control area for the proteinuria s.tudy has been the village
Kitaaizu, which is 10 km southwest, of Bandai. If no special conta-
mination exists it can be assumed that cadmi.um in rice is
not higher than 0.1 ppm in this village.
The target population in the epidemiological study was 1827
man and women over 30 years of age in the polluted area and
272 women1in the control area (Kitaaizu). The average prevalence
of proteinuria among'the 1324 participants from the polluted
area :in-,.1970 was: 1-2. 3:%:- and among.; th;B/j2(15'>in- the '/control, area - ,
4.7% (Fukushima Prefecture, 1971 b). Nothing is mentioned
as to whether or not the studies were carried out on a blind
basis. Data on age distribution are available for those
who underwent the second screening. The criteria for selecting
persons for the second screening.was proteinuria - in the
polluted area and proteinuria + in the control area. Further
in the polluted area also persons with glucosuria were inclu-
ded. This makes it impossible to compare age specific prevalences
for epidemiological analysis.
6.3.6 Annaka area of Gumma Prefecture
In Annaka a large zinc refinery has polluted surrounding
farmland with cadmium primarily through air. Operations started
in 1937 and cadmium .production dates from 1948. The monthly
production of zinc has increased rapidly during the last
decade (Figure 6:12). , .
An epidemiological study was performed in 1969-1970 (Kakinuma
*y . .
et al., 1971) according .to$the old standard method. Average
cadmium concentration in rice in 1968 was .0.38 ppm in the
polluted area and 0.30 ppm in the ""control" area (Table 6:4).
In 1971; paddy soil and unpolished rice were studied in the
polluted area and surrounding areas (Gumma Prefecture, 1972).
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-89- . |
\
!
An average of 0.40 ppm cadmium in 166 samples of unpolished
rice in the polluted area was found. The "control" area was \
not studied, but in a village 1 km from the "control" area ;
and considered to be non-polluted, the average cadmium concentra-.-
t
tion out of 3 samples was 0.48 ppm. It can therefore be assumed '.
that the similarity between the polluted and the "control"
area in cadmium concentration of rice in 1968 was not accidental. ;
i
It may even be argued that the "control" area in Annaka seems j
to have a similar cadmium exposure as the polluted area. Nevertheles:-
it was calculated with the National Nutritional Census method |
(Japanese Association of Public Health, 1970) that daily cadmium !
intake was 211 pg in the polluted area and 113 \ yg in the ,
"control" area (see section 6.2.5). This was due to an assumed i
low cadmium concentration in other foodstuffs from the "con-
trol" area.
The "control" area used in the studies on daily intake is the
same as the one used in the epidemiological study, where a
total of 2397 persons (men and women over 30 years) in the
polluted area (84% participation) and 895 persons in the "control"
area (74% participation) were studied. Age-related prevalences
of proteinuria have been published by Kakinuma et al., 1971,
and are shown in Table 6:12. The studies in tha polluted area
and in the "control" area were not performed at the same time
and not on a blind basis (Nomiyama, pers. comm.). According
to Kakinuma et al., 1971, proteinuria was defined as a rating
of * or higher in either the Trichloracetic acid method or
the Sulfosalicylic acid method. !
The data in Table 6:12 do not show differences in the age- \
related prevalence of proteinuria between the "control" and !
the polluted area. It should be pointed out, however, that ;
the difference in cadmium exposure judged by the concentration j
of cadmium in rice seems to be trivial. There is an increase i
i
in prevalence of proteinuria with age.
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-90-
Another factor of importance is that the production of the
factory has increased 6-fold during thu last decade (Figure
6:12) .and has been high only the last years. Thus the. high.
values in rice do not necessarily implicate ,a high cadmium
exposure in the past. In the Annaka-area there must have been
an exposure also via ambient air. The'magnitude of such exposure
has not been possible to evaluate. -
6.3.7 Dmuta area in Fukuoka Prefecture
The cadmium source in this area is a, refinery causing mainly
airborne pollution. Epidemiological data have been collected
in 1970 (Ministry of Health ,and Welfare, 19.71 c).and in 1972
(Matsushiro, pers.comm.).
The refinery started production in 1913 and two plants were
added in 1915 and 1954. Data from the Ministry of Health and
Welfare, 1971c,indicate that only a-,slow increase in production
has occurred the last decades; Air concentrations of cadmium
in 1969 were the highest measured in Japan (Yamamoto, 197.2).
At one place .a maximum 24-hour value of 3 y&/m was found.
'According to Yamamoto, 1972, the average cadmium concentration
.in 91 samples of rice was as high as 0.72 ppm. Intake from
all food except rice was calculated to be 75 yg to 115 yg
among farmers, depending on area. Total daily intake has been
calculated to vary between 60 yg and 280 yg (Ministry of Health
and Welfare, 1971c). Using the rice-method (described in section
6.2.5) the daily intake can be calculated to be about 500 -yg.
Prevalence of proteinuria was studied in the polluted area
in 1970 and 1972 (Ministry of.Health and Welfare, 1971c, and
Matsushiro, pers. comm.) and in 1970 in a control area, Fukuoka
city. The exposure to cadmium in the control area is not known.
Information on methods used for protein determination has not
been available to us for the 1970 study, In 1972 Trichloracetic
acid or Sulfosalicylie acid method was used (Matsushiro, pers.
comm.). The selection of study populations' is not known to
us nor are the participation rates. With these reservations
-------
-91-
the prevalences of protuinuria in polluted as well as control
area are given in Table 6:13. In the polluted area the preva-
lence increases with age both in 1970 and 1972. The control
area studied in 1970 showed higher prevalences than the polluted
area (1970).
In the report from the Ministry of Health and Welfare, 1971
c, many values on cadmium in urine are given, but not information
on methods. The data are given without reference to age. It
can be mentioned that the group with the highest cadmium excretion
consisted of farmers with proteinuria. These 130 persons had
an average cadmium excretion of 10.3 yg/1 (range 0-77.7 yg/1).
Unfortunately, no information on cadmium excretion in farmers
without proteinuria was given. Those with proteinuria in the
control group (49 persons) had an average cadmium excretion
of 1.8 yg/1 (0-5.1 yg/1). In the control area there were reported
data on cadmium excretion among those without proteinuria.
These values are not given as concentrations, but as total
amounts excreted per day. A mean of 2.8 yg/day (range 0-7VS
yg/day was reported among 38 persons.
6.3.8 Uguisuzawa area in Niyagi Prefecture
Epidemiological studies have been performed in connection with
pollution of Uguisuzawa town. In 1969 638 persons of the "most
polluted" area, 220 persons of a neighboring area and 238 persons
in a control area underwent a first screening according to
the old standard, method (see section 6.2.2) (Miyagi Prefecture,
1970a). The prevalence of proteinuria (Trichloracetic acid
method) in women over 30 years of age was as follows: 50% in
the "most polluted" area, 60.4% in the neigboring area and
39.6% in the "control" area. In 1970 a new study using "testtape"
(which is less sensitive for tubular proteinuria) was performed
(Ichinowatari, pers. comm.). This time only 117 persons were
studied in the "most polluted" area and the proteinuria prevalence
was 3% (Hasegawa, 1972). A new control area was used, from
which 437 persons were studied and the result was 4% proteinuria
(Hasegawa, 1972).
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-92-
In Uguisuzawa there, are a mine and a .refinery, which have polluted
both air and water. The water of a small river passes the "most
polluted" area close to the mine at a rapid pace and then converges
with another river and flows more slowly through the neighboring
area (Ichinowatari, pers. comm.), which lies about 10 km downstream.
from the mine. The river continues another 10 km and passes
through the control area used in 1970 and then after another
10 km passes through the control area used in 1969. This distance
would not at all exclude cadmium contamination. Note that the
distance from the Kamioka mine to the polluted Fu.chu area
in Toyama Prefecture is about 30 km.
A nutritional study from 1969 (Miyagi .Prefecture/ 1970b) .has
calculated the daily intake in the polluted area (including
the neighboring area, Ichinowatari, pers. comm.) to 347 }ig
cadmium and in a control area to . 80 pg (Table 6:4). This control
area, however, is not the same as the ones used in the epidemio-
logical studies and cannot be contaminated by.the river flowing
from the mine.
6.4 DISCUSSION .
A large amount of epidemiological data has been collected
during recent years in various parts of Japan, where cadmium
pollution of the environment has been suspected. A standard
screening method has been established by the Ministry of Health,
but the major aim .of this method is to find cases of Itai-
itai disease. In other words, the screenings are more individual-
oriented than population-oriented.
The way of delineating "polluted" and "control" areas has not
been standardized.,In some control areas, the exposure has
not been estimated, and in at least one area it can be assumed
that also the "control" area was polluted.
Methods for proteinuria analysis vary among areas, and a choice be-
tween' Trichloracetic acid and Sulfosalicylic acid method is .ex-
-------
-93-
plicitly allowed by the standard screening method itself. Though
the s.tandard screening .method sets criteria for evaluating
proteinuria,. very, few .of the published studies give detailed
data on qualitative ratings ( -,. -, +, .+ + , + + + ) Of proteinuria.
The prevalences of proteinuria are as a rule only based on
whether or not proteinuria was present. Furthermore, in some
reports proteinuria has been based on a rating - or higher
and in other studies + or higher.
The resulte of the proteinuria studies vary greatly among different
areas. From what was just mentioned it is clear that differences !
in analytical methodology may play a large role. Another reason i
i
may be the effect of expectation.. If the studies are not blind :
and the analyst knows that the sample i~s from a polluted area j
or a control area, he/she might unconsciously use different j
criteria for the two areas. This effect may work in either
direction, which means that an existing difference may be hidden
r
or a non-existing difference may be created. When using the
Trichloracetic acid or Sulfosalicylic acid methods the critical
part of the evaluation is the discrimination between a rating
of - or higher and + or higher. Judging from the methodology
studies published (see section 6.2.4) the effect on prevalence
of proteinuria of errors in this discrimination in certain
studies may be very high.
The only attempt to evaluate information from different areas
has been made by Hasegawa, 1972. He concluded that no effect
of cadmium could^be ascertained with the epidemiological analy-sis
he used. According to him, this lack, of effect might depend .'{ ' ,
on level of exposure, i.e. not high enough, or a lack of a ;
sensitive method. Unfortunately, he only used the classificatibn
"polluted" versus "control" as a means of estimating the population's.
exposure. As shown in section 6.3 the population of the control
area is not necessarily unexposed. Furthermore, Hasegawa did
i
not study age-related effect data. ,
In most polluted areas for which age-related proteinuria prevalences
have been possible to calculate (Fuchu, Tsushima, Annaka) there
-------
. -94-
is a substantial increase in prevalence with age. The new data
from fuchu certainly confirm the earlier conclusion in CITE
that in that area the causal role of cadmium for increased
prevalence of proteinuria with increase in age is obvious.
It is hot possible in the other areas with the data available
to assess whether or not the increase with age is also causally
related to the longer exposure to cadmium. The main reason !
for this uncertainty is that virtually no data exist from true J
control areas on prevalence of proteinuria within different
age groups as analyzed by the same methods applied in the polluted j
areas. j
When it comes to an evaluation of those areas where no age j
specific data are available the following can be said. In for
example Ikuno, Uguisuzawa and Kakehashi, where extensive studies
have been carried out, prevalence of proteinuria was found ',
to be about 40-60%. This certainly means that the occurrence |
of proteinuria was higher than usual in Japan. In Ikuno the i
polluted area showed a prevalence of about 60% (in people above !
30 years) while in two control areas corresponding figures
were about 4 and 9%. It is true that in another control area ,
' '. *
an average value of 33% was reported. In Kakehashi no control
area was examined while in Uguisuzawa the control showed about ,
the same prevalence of proteinuria as the exposed area. This ;
control area, however, was located along the same river, whijch
had polluted the exposed area. Other studies, like the one '.
in Annaka, have clearly shown that a control area may be as .' i
contaminated as a polluted area. ;
In Fuchu and Bandai within the same studies it was possible
to find either a clear dose-response relationship or a diffe-
rence compared with a control area. The data from Omuta are
difficult to interpret. In one study the data indicate a lower
prevalence of proteinuria in a cadmium-polluted area than in
a control area.
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-95-
A question of importance of course is whether the daily intakes
(between 200 yg and 500 yg) could he considered sufficient
to give chronic cadmium poisoning. If it is assumed that an
exposure of 50-75 yg/day during 50 years gives about 50 ppm
in kidney cortex a corresponding exposure to 200-300 yg/day
would give about 200 ppm as an average. Low calcium intakes
or vitamin D intakes would enhance Cd-absorption and lower
daily intakes than 200 yg might then give effects.
Another approach in evaluating effects is to discuss cadmium
excretion in the urine. It can be seen from data by Tsuchiya,
Seki and Sugita, 1972 a (section 4.3.4.1) that a mean urinary
excretion of about 2 ug Cd/liter corresponds to a mean cadmium
level in kidney cortex of about 100 ppm after long term low
level exposure in a so called non-polluted area. As was discussed
in section 4.3.4.1 at this type of exposure there is reason
to believe that urinary excretion is related to body burden.
It has not been shown that a threshold exists, at which the
urinary excretion of cadmium suddenly would increase without
.concurrent tubular dysfunction. As was discussed in section
5.1.3 the critical cadmium level in kidney cortex at which
proteinuria might occur was estimated to be 200 ppm. The cor-
responding urinary excretion would,if it is assumed that kidney
cortex concentration is proportional to body burden, be 4 yg
Cd/liter (200/100 x 2). In for example the study in Ikuno the
criteria for selecting the polluted areas was a minimum average
cadmium excretion in urine of 9 yg/liter. In two villages in
Kakehashi, mainly among persons with proteinuria, the cadmium
concentration in urine was on an average about 22 yg/liter.
Even if the urinary excretion is not directly related to kidney
cortex concentration in the same way as to body burden, all
human as well as animal data strongly support tubular dysfunction
associated with long-term cadmium exposure as the reason for
such a high excretion.
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' "96~
In our report Cadmium iri the Environment it was stated'that
there was reason to b.elieve that cadmium intoxication had occurred
in at least one part of Japan other than the Toyama Prefecture
and that the cadmium problem in Japan might well be far reaching.
\ , I
Though the new data presented in this report are often difficult
to interpret due to sometimes severe methodological inconsistencies
there can be no doubt that the conclusion reached in our earlier
report has been strengthened considerably.
-------
TABLE 6:1 Result of comparison of proteinuria methods in two areas
of Toyama. (From Fukuyama, Shiroishi and Kubota, 1971).
Total number examined
Polluted area
Control area
165 (100.0)
225 (100.0)
Sulfosalicylic
acid method
21 (12.7) 3 (1.3)
40 (24.2) 7 (3.1)
19 (11.5) 4 (1.8)
125 (75.8) 218 (96.9)
Trichloracetic
acid method
13 (7.9) 5(2.2)
37 (22.4) 25 (11.1)
24 (14.5) . 20 (8.9)
128 (77.6) 200 (86.9)
G-25 gel fil-
tration method
63 (38.2) 3 (1.3)
110 (66.7) 6 (2.7)
47 (28.5) 3 (1.3)
55 (33.3) 219 (97.3)
Numbers indicate how many people, were studied in each group;
numbers within brackets are vertical relations (%).
-------
TABLE 6:2 Comparison between disc electrophoresis and-other proteinuria
methods.' (Calculated from a table by Fukuyama, Shiroishi and.
Kubota, 1971).
Total
Sulfosali.cylic acid
method > ± or higher
Trichloracetic+
acid method > - or higher
SA or TCA > - f
G-25 gel filtra-
tion method +
Disc ( + J
N %
50 " -
33 82.5
25 67,6
36 67.9
47 74.6
; Disc (-)
N ' ; %
42
'5 12.5
. 8 21.6
11 20.8
11 17.5
Disc (- )
N %
73
2 5.0
4 . 10. .8
6 11.3
5 7.9
Total
N %
165
40 100
37 ,100 .
53 100
.63. 100
Numbers within brackets are horizontal relations (%). N = Number of persons
examined.
-------
99
TABLE 6:3 . Result of comparison of proteinuria methods in Annaka.
(From Kakinuma et al., 1971).
35% Trichloracetic aci'd method
(TCA)
Rating + * Total
3% Sulfosalicylic
acid method
(SA)
+ 257 39
- 31 233
- 2
Total 288 274
17
48
1809
1874
313
312
1811
2436
Figures indicate the number of persons with different combinations of
ratings according to the trichloracetic acid method and the sulfosalicylic i
acid method. '
-------
100
TABLE 6:4 Average daily cadmium intake for adults
(From Japanese Association of Public Health, 197Qb).
National
nutrition
Area
Uguisuzawa
(Miyagi Pref . )
Annaka
(Gumma Pref. )
Tsushima
(Nagasaki Pref.
Kiyokawa
(Oita Pref. )
polluted
control
polluted
"control"
polluted
^control
polluted
control
census
yg cd
244.7
84.5
211.0
113.4
215.2
59.1
221.6
79.2
N
513
158
676
1.38
567
284
666
224
Rice
cone.
of Cd
ppm
0.30
0. 11
0.38
..0.30
0.37
0.08
0.18
0.03
Total
diet
coll.
yg Cd
180
108
281
99
21 3
104
391
N
6
6
6
6
8
8
6
6
Range
(total i
diet coll ) .!
yg Cd !
119-277 -. :
78-141 "'
1.48-485. .
71-132
49-533
58-192 .
117-1209
not the control area used in the epidemiological studies
N = number of persons examined.
-------
101
TABLE 6:5 Average G-25 protein quotient in relation to exposure
level and exposure time.
(Calculated from Figure 2 in Fukuyama and Kubota, 1972 b;
Exposure time (years) 0-29 20-39 40-59 60+
Exposure
level
High
Medium
Low
6.4
6.7
7.0
6.9
8.0
7.1
15.3
14.3
10.0
24.2
21.4
17.2
-------
102
TABLE 6:6 Number of persons in 0-area and a home for the aged with
different patterns in disc electrophoresis.
(From Shiroishi, Tanii and Kubota, 1972)
Disc electrophoresis pattern
Group studied
0 - a re a
0-area
Home for the aged
N
104
young
(95.4)
46
old
(88.5)
91
(86.6)
K I
2 .- '
1(1.8)
4
(7.6,)
7 2
(6.6) (1.9)
0
3
(2.7)
2
(3.8)
5
(4.7)
N = normal pattern
K = glomerular pattern
I = Itai-itai pattern
0 = other pattern
Figures within parenthesis are percent of the total in group
-------
103
TABLE 6:7
Concentration of cadmium in unpolished rice from
different villages of Tsuchima,
Village
Range of reported
cadmium concentra-
tions from 1969 -
1970° (ppm)
Averages Oct. 1970
Polluted
Kashine
Shimobaru
Komoda
Shiine
C o n t ro 1
Are
0.38 - 0.89
0.30 - 0.50
0.36 - 1.32
0.44 - 0.60
0.50^
(
0.
0.
0.
0.
) =
60
42
50
58
number of samples
(58)
(39)
(34)
(52)
only studied in 1969 (Nagasaki prefecture, 1971 a)
results from five different studies (Nagasaki prefecture, 1971 a)
average of results from a study by the Ministry of Agriculture and
Prefectural Agriculture Center, October 1970 and a study by ths
Ministry of Health and Prefectural Pollution Bureau, October 1970.
-------
104
TABLE 6:8
Cadmium concentration in rice from the. Ikuno
area, 1971. (Analyzed by the Agriculture Buraau
of Hyogo Prefecture according to Ikuno Mining
Poll., 1972) ...-.'
Area
Ikuno town (I)
Ookochi town (0)
Kamisaki town (K)
Ichikawa town (1C)
Fukusaki town (F)
Kooji town (KO)
Number of
rice samples
23
57
.30
20
5'
10
Cadmium
Maximum
1.43
1.15
0.98
0.49
0.37
0.72
concentration
Minimum
0.15
0.01
0.15
0.01
0.03
0 . 06
(ppm)
Average
0.69
0.35
0.48 -
0.19
0.15
0,27
-------
105
TABLE 6:9
Prevalence of proteinuria in areas of Hyogo Prefec-
ture. Both sexes, all over 30 years (From Hyogo
Prefecture, 1972)
Area
Ikuno
A "Kaibara"
6 "Chichigawa"
C "Hamasaka"
Result of proteinuria
analysis. Sulfosalicylic
acid method (% of persons
examined)
Targst
population
1699
1935
2514
771
Persons
examined
1560
1574
2002
638
+
58
33
4
9
Rating
5
8
5
2
-
37
59
91
89
-------
106
TABLE 6:10 Relationship between cadmium concentration in rice,
urinary cadmium concentration and globulin/albumin
ratio (Watanabe, unpublished data) . .
Village
1
2
3
4
5
6
Cadmium
in rice
(ppm)
0.33
0.35
0.61
0.88
0.91
1.10
Number . ,
of urine
samples
35
34
49
,50
27
55
Urinary Cd
" yg/1
7.5-5.2
8.0-5.1
9.4-5.3
. 12.9-6.1
13.3-9.0
13.8-10.7
Glob/Alb-ratio
0.75-0.61
0.81-0.58 .
1.80-0.91
1.79-0.84
1.41-0.95
1.97-0.82
-------
107
TABLE 6:11 Result of an epidemiological study in Kakehashi river
basin (From Ishizaki, 1972).
Village
Kanahira Gokoji . Kaneno Shorenji
Cadmium concentrations in +
rice (ppm) average * S.D. 0.80-0.30 0.23-0.14 0.32-0.07 0.34-0.28
Persons examined and parti-
cipation (in brackets) 77(87%) 54(94.7%) 60(87%) 18(100%j
Prevalence of proteinuria ;
(% of persons examined,
sulfosalicylic acid method) 39.0 22.0 30.0 28.0
Prevalence of glucosuria
(% of persons examined,
orthotoluidine method) 33.0 17.0 18.0 11.0
Concurrent proteinuria
and glucosuria
(% of persons examined) 22.0 13.0 10.0 9.0
Number ofpersons
examined for cadmium
in urine 33 13X 17X 18
Cadmium concentrations
in urine (yg/1)
average - S.D. 23.3-11.6 21.2-10.5 11.5-4.8 10.1-6.5
x mainly cases with proteinuria
-------
108
TABLE 6:12
Prevalence of proteinuria in Annaka area.
(Calculated from Kakinuma et al., 1971)
Females, polluted
Females, "control"
Age group:
30-39
40-49
50-59
60-69
70 +
Total
Age group
30-39
40-49
50-59
60-69
70 +
Total
N = number of
\ - prevalence
higher or
N %
337 9.8
351 8.3
292 11.0
193 17.6
128 . 22.6
1301 12.1
Males, polluted
N %
307 4.2
273 6.2
226 6.2
201 14.9
89 14.6
1096 . 7.9
persons studied
1
of proteinuria (either*
Sulfosalicylic acid + 01
N %
85 5.9
156 6.4
125 10.4
87 ' 20.7
54 11.1
507 10.3
Males, "control"
N ' . %
51 3.9
115 5.2
100 13.0
84 10.7
38 15.8
388 9.3
Trichloracetic acid + or
higher)
-------
109
"ABLc 6:13 Protoinuria urr,onv= inhabi tcints of LhB pul lu l.ijd ar^cj in
and of the control area in Fukuoka. (From Ministry o T
and Welfare, 1'J/L cJ, and Motuushiro, pors. comm. )
Famale farmers
A '-2
-39
40-43
-~ d - 5 9
:>59
.70 +
Total
M
20
419
325
351
310
1435
PolluL
1970
%
0
2.
2.
5.
13.
5.
ed
6
5
8
9
8
Polluted
f'.g3
-39
4C-49
50-59
50-59
70 +
Total
N
10
318
262
285
230
1105
1970
%_
0
1.
1.
3.
16.
5.
3
9
2
5
1
area
N
84
102
69
68
94
417
Male
area
N
48
84
76
49
57
314
1972
*
11
14
11
16
34
18
farmers
1972
%
4
7
13
16
28
13
Control uiCja '.
1970
N %
.9 99 8.1
.7 126 8.7
,6 113 8.0
.2 87 10.3
.0
.2 425 6.8
Control area
1970
N %
.2 .
. 1
.2
.3 87 13.8
.0
.4 87 13.8
': - number of persons examined
^, :~- prevalence of proteinuria (1970 method not reported, in 1972 Trichlcr
acetic acid methods were used, Matsushiro, pers. comm.)
-------
110
%
80-1
.2 60 H
3
C
JJ
§ 40-
a
20-
Male
Female
/
30 40 50 60 70 30 40 50 60 70 years old
60 i
40-
W)
O
O)
20-
30 40 50 60 70 30 40 50 60 70 years old
Endemic district of Itai-ltai disease
C----0 Border district
X * Non endemic district
FIGURE 6:1 Prevalencs of proteinuria and glucosuria
among men and women in different age grdups
at the 1967 epidemiological study of itai-itai.
disease in Toyama. (From Ishizaki, 1969 ).
-------
Ill
% proteinuria
50-
40-
30-
20-
10-
Male
Female
40 50 60 70
40 50 60 70 years old
o o
- mOSt polluted Villages, Kashine. Shilne
leSS polluted Villages. Shimobaru. Komoda
it x Control Villages, Hikage-Kamiyama. Are (NO cases of proteinurio
found among males )
f,: '/ fruvnlunoH of fjrnLn L nui-in nrnonj'. intin .ind .
. in iJiffuront HJ;H j'.roups in vilLij'.us nf I sushim.i.
ffr-nrii Nnf.oJinki l'rt»ftii:tui'u, 1H70).
-------
112
6t
= polluted areas
~ othBr areac montioned
.'! f'l(ji;u!; in .'Iripnn rnunti nntui in f.hi.'i rnpr»rt.
-------
113
o
1km
O°
cone, in soil
3.0 ppm or higher
2.0-2.9
1.0-1.9
9 ppm or lower
irrigation canal
Thin lines show boarders of hamlets included
in the study. Cadmium concentration in paddy
soil is an average of samples from top soil
at water inlet, center and water outlet of
paddy.
r-IUJRL L:4
Distribution of areus studied, irrigation
fji'inala and cadmium in poddy soil. (From
\ ukuyamfi ,.intJ Kubotii, l^/'Slt).
-------
114
polished unpollslwd
rtc*
ppm
FIGURE 6:5 Concentration of cadmium in rice in the
Fuchu area, 1967. (From Ishizaki, Fukushima
and Sakamoto, 1968).
-------
115
bariiUoqnu beritlloq
ah
mqq --CO.S;
ff.l-001
j»M-
adJ ni soia ni muimbeo "+o noij-s-ii
T) . '\ 3 91 , B a'i B u ri o LI -I
.(8391 t o J1 om e /H & 2 h n B
-------
116
protein-
urid
glucos-
uria
%
40
\
"30
20
10
y=9.23x + l.l
r=0.918
-. \
Cd !/
y?
' J L _
y=0.105x+4.4
r =0.931
Pb f
V* *
4
y=0.0428x-0.4
r=0.947
jS
'/' f
III III!
12 3 100 200 300 200 400 600 800
ppn " PPm fPm
y?=7.06x+11.2i y=0.081x+13.6 y=0.032x flO.4
% r=0.874 t r=0.893 r=0.884
40
30
20
10
Cd j^
s*
i i i
'. *>S
»^
^/
-
^
Zn ^^
s\
. \ \ \
1 2 3 100 200 '300 200 400 600 800
ppm ppm ppm
Average metal concentration in
soil within villages
FIGURE 6:6 Village averages .of proteinuria and glucosuria
in relation to concentration of heavy metals
in paddy soil. Regression equations and
correlation coefficients. (From Fukuyama
and Kubota, 1972c). '
-------
Home for the aged in Toyama City
% of total number
ol persons studied 40
10 20 30
mg/dl
proteinurlo
Old group in 0-area
%
80
9/o of total number
of persons studied
Young group in 0-area
%of total number
of persons studied
0 10 20 30
proteinurla
FIGURE fi:7
Distribution of urinary protein concentration
levels among people in 0-area and a home for
the aged in Toyama city. (From Shiroishi,
Tanii, and Kubota, 1972).
-------
118
TO CONTROL
AREA (ARE)
HIKAQE-
j KAMIYAMA
SHIINE
O« MINE
FIGURE 6:8 Area under investigation, Tsushima Island
(From Nagasaki Prefecture, 1970).
-------
119
Ichikawa river basin
5km
= town borders (I, 0, K, 1C, F).
The numbers are average cadmium concentrations
in rice within towns.
Nap of Ichikawa river and polluted areas in
Ikuno area. (Redrawn from a map in Ikuno Mining
Poll., 1U72).
-------
120
Kakchashi river
Shorenji
Hukuriku mine
Former Ogoyo
mine
I l I
5km
FIGURE fi:10 Lncrttinn nf t-.hr v/illflpqr, i n»''"Rt i p.Ht prt in
Kakphr»«?hi rivRT basin. (From I^hi/^ki. 1972).
-------
121
KANAHIRA
rice .0.8010.30 ppm
GOK03I
rice<0.23t0.t4ppm
m9/dl rog/d,
:
50
.0
D
(A
o
u
jj
O
10
XX XAA A** I
4- A
A A
* 50
1C
x^4
." * A \
> * X *
X X
X X
X> rf
- K o 10
X ^» X A
X
X XXAX
x*x x
*# ? i _±. fig/ji c
x
X
J^
XX
%**
XX
f/x*** A
X
Xxxx
X
*x
0 25 50 0 25
Proteinuria
50
50
M
O
U
3
O
to
XX
XV
vxx
X XX
KANENO
rice. 0.32±0.07ppm
50
m9/dl
m9'dl
50
10
SHORE NJI
rice.0.34±0.28p
0 25
Proteinuria
A m tubular pattern in disc electrophoresis
C - glomerular pattern
X o normal pattern
xA x
x
X
XXX
X
X X
X
** x
0 25
i
50
m9/dl
FIHIJPF 6:11 Rpsults of urinp analysis of mRn and
women nvnr 'if) years of app in Kakehashi
river hasin. (From Ishizaki, 197?).
-------
122
Production of Zinc.
Tons/month
10000-
5000-
1935 1940 1945 1950 1955 1960 1965 Year.
f'J.GIJRL' fj.-lZ Changes in zinc production with time in the
Annaka refinery. (From Mr. Fujimori, vice-
president of thu Annuka rofinery, pero. cem*>. 1 .
-------
-97- ,.1.3
CHAPTER 7 THE CAUSE OF THE ITAI-ITAI DISEASE
In our previous review. Cadmium in the Environment (CITE) it was
concluded that all available data strongly supported the con-
clusion that cadmium is a cause of the Itai-itai disease^ It was
stated, however, that it might well be that cadmium had acted
upon a population particularly sensitive because of deficient
consumption of certain essential food ingredients and vitamins,
particularly calcium and vitamin D.
It is not the aim of this report to go into details about the
Itai-itai disease. However, since CITE was published, a
new hypothesis about its etiology has been introduced by
some researchers (Takeuchi and Naito, 1972) in Japan. They
argue that the Itai-itai disease might have been caused by an
initial vitamin D deficiency and a subsequent vitamin D poi-
soning. The article in which this hypothesis is introduced is
written in the form of a discussion and the hypothesis is not
supported by any factual data.
The hypothesis implies that vitamin D deficiency should be
much more pronounced in Fuchu than in other arsas of Toyama
Prefecture. There is no substantiation that this is the case.
As was mentioned in CITE, the dietary conditions in Fuchu did
not differ from those in neighboring areas, where the disease
was not found. Still more inconsistent with the vitamin D hypoth-
esis is the fact that when the Itai-itai disease did occur
in Toyama areas outside Fuchu, it only occurred in areas irrigated
by the Jintsu River. Moreover, the fact that in most cases
it was necesssary to give very large doses of vitamin D over
prolonged periods definitely does not speak in favor of vitamin
D deficiency alone as the cause of osteomalacia; instead, it
strongly favors that the osteomalacia was secondary to some
renal damage.
According to Hagino, 1973, 30 Itai-itai patients were treated
before 1948 and 1950 with 5-10 g cod liver oil (corresponding
-------
-98- .
to about 1,000 I.u. vitamin D) per day for 3-6 months, but
the bone symptoms did not recede. This dose should be suffi-
cient for treatment of vitamin D deficient osteomalacia (Docu-
menta Geigy, 1960, Merck Manual, 196G, and Arnstein, Frame
and Frost, 1967). Hagino, 1957, and Nakagawa and Furumoto,
1957., report that large doses of Vitamin D are needed to reverse
the bone symptoms. Hagino, 1973, gave 50,000-100,000 I.u./day
in 1955-1957 and 100,000 I.u. per day during 1967-1969. When
.treatment was interrupted (Hagino, 1973) the bone symptoms
returned. Nakagawa, 1960, reported on 30 patients, whose treat-
ment started in 1955-1958. To out-patients, an average of 20,000
I.u vitamin D/day was given and to in-patients, 100,000 I.u./day.
In man.y cases, the pain was relieved after a couple of months
and the patients could resume their everyday lives. Murata,
Nakagawa and Hirono, 1972, reported that 100,000-200,000 I.u./day
had been used for years on 5 of these patients.
As mentioned, Takeuchi and Naito, 1972, also argued that treat-
ment with large doses of vitamin D could have been the cause of
kidney damage in Itai-itai disease. To this 'can be said first
of all that cadmium-induced dose-related proteinuria is seen in
many persons (also in men) other than Itai-itai patients (see . .
section 6.3.1). There are no data that such ~a massive outbreak
of proteinuria in men as well as in women could have been caused
by excessive treatment with vitamin D. Furthermore, kidney damage
was common in Itai-itai patients already in the 1950's, i.e.
even in patients that had not received vitamin D treatment. .
Backing for this assertion can be found e.g. in the report of
Nakagawa, 1960, describing 30 Itai-itai patients from the Shinbo
district who were studied 1955-1958. All of the patients had
proteinuria (Sulfosalicylie acid method) and some had glucosuria
(Nylander method) as well. Vitamin D had not been taken by the
patients before they were examined (Nakagawa, pe.rs. comm. ).
There are some other data related to postulations about
kidney damage in the mid-1950's. Taga et al., 1956, reported
bone symptoms among 10 patients. Two of these patients had died
-------
-
-------
126
-100-
it is not possible to make a proper evaluation of less severe
manifestations of chronic cadmium poisoning.
-------
r\u ru
Abdullah, M.I. and Koyla, L.G., Tliu determination of copper,
lead, cadmium, nickel, zinc and cobalt in natural waters by
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Alexander, F.W., Delves, H.T., and Clayton, B.E., The uptake.
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Allen, H.E., Matson, W.R., and Mancy, K.H., Trace metal char-
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1 09
Berlin, M. and Ullberg, S., The fate of Cd in the mouse,
Arch. Environ. Health, 7, 686, 1963.
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-------
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Berry, J.-P., les lesions rSnales provoquees par la cadmium.
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Bryan, S.E. and Hayes, E.F., Partial characterization of liver
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Chen, R. , Wagner, P., Ganther, H.E., and Hoekstra:, W.G.,
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