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Toxicity to reproduction

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Administrative data

Endpoint:
one-generation reproductive toxicity
Remarks:
based on generations indicated in Effect levels (migrated information)
Type of information:
experimental study
Adequacy of study:
key study
Study period:
no information
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: reliable with restrictions. Well documented publication, but some details are missing. Useful for evaluation.
Cross-referenceopen allclose all
Reason / purpose:
reference to same study
Reason / purpose:
reference to other study

Data source

Reference
Reference Type:
publication
Title:
Toxicity, fertility, teratogenicity, and dominant lethal tests in rats administered cadmium subchronically II. Fertility, Teratogenicity, and Dominant Lethal Tests
Author:
Sutou S, Yamamoto K, Sendota H and Sugiyama M
Year:
1980
Bibliographic source:
Ecotox. Environ. Saf. 4:51-56

Materials and methods

Principles of method if other than guideline:
Method:
Males and females within each treatment group (+ control) were mated 6 d/wk for 3 wk changing partners every week if needed. Cd was
administered during the mating period. Copulation was confirmed by detection of spermatozoa in vaginal smears. Pregnant F were administered
Cd during gestation and killed on Day 20 of gestation for developmental test (fetal examination). Nonpregnant females were killed after a total
administration period of 13 wk.
Additionally: After a total of 9 wk of administration, males were mated with 2 virgin females per male per week for 6 wk. Pregnant F were killed on
Day 13 of gestation for dominant lethal tests (examination of the numbers of corpora lutea, live fetuses, early deaths (no remnants of fetuses), and
late deaths (remnants of fetuses)). One week after the cessation of dominant lethal tests, which represents a recovery period of 50 d, male rats
were killed and examined.
GLP compliance:
not specified
Limit test:
no

Test material

Reference
Name:
Unnamed
Type:
Constituent
Details on test material:
-Name of test material-CdCl2,
-Source-Wako Pure Chemical Industries, Ltd

Test animals

Species:
rat
Strain:
Sprague-Dawley
Sex:
male/female
Details on test animals and environmental conditions:
- Origin/housing: purchased at age of 4 wk from Shizuoka Agricultural Cooperative Association for Laboratory Animals.
The animals were freely supplied with pelleted dry chow (NMF, Oriental Yeast Co.) and water and kept in wire cages in pairs. The cages were placed in a fully air-conditioned facility where the temperature was regulated at 24 ± 1°C, and the humidity at 55 ± 5%. After a taming period of a week, the test
was started.
- Age at start of study: 5 wk
- Weight at study initiation: no data

Administration / exposure

Route of administration:
oral: gavage
Vehicle:
not specified
Details on exposure:
no information
Details on mating procedure:
Method:
Males and females within each treatment group (+ control) were mated 6 d/wk for 3 wk changing partners every week if needed. Cd was
administered during the mating period. Copulation was confirmed by detection of spermatozoa in vaginal smears. Pregnant females were administered Cd during gestation and killed on Day 20 of gestation for developmental test (fetal examination). Nonpregnant females were killed after a total
administration period of 13 wk.
Additionally: After a total of 9 wk of administration, males were mated with 2 virgin females per male per week for 6 wk. Pregnant F were killed on
Day 13 of gestation for dominant lethal tests (examination of the numbers of corpora lutea, live fetuses, early deaths (no remnants of fetuses), and
late deaths (remnants of fetuses)). One week after the cessation of dominant lethal tests, which represents a recovery period of 50 d, male rats
were killed and examined.
Analytical verification of doses or concentrations:
not specified
Details on analytical verification of doses or concentrations:
no information
Duration of treatment / exposure:
Exposure period: 6 wk prior to mating + 3 wk mating period
Premating exposure period (males): 6 wk
Premating exposure period (females): 6 wk
Frequency of treatment:
Once daily for 9 wk
Details on study schedule:
See test method under 'Details on mating procedure'
Doses / concentrations
Remarks:
Doses / Concentrations:
0, 0.1, 1.0 and 10.0 mg Cd/kg bw/d
Basis:
no data
No. of animals per sex per dose:
14 males and 14 females per treatment group (and control)
Control animals:
yes
Details on study design:
no information
Positive control:
none

Examinations

Parental animals: Observations and examinations:
reproducitve performance
Oestrous cyclicity (parental animals):
no information
Sperm parameters (parental animals):
no information
Litter observations:
presence of gross anomalies and viability
Postmortem examinations (parental animals):
no information
Postmortem examinations (offspring):
skeletal anomalies
Statistics:
t-test: to determine the significance of differences between average numbers of corpora lutea, total implantations, and live fetuses per female,
average fetal body weight and placental weight per litter, and average length of fetal body and fetal tail per litter for each treatment, compared with thecontrol values. Preimplantation losses were determined by subtracting the number of total implantations from the number of corpora lutea. The
preimplantation losses, early deaths, late deaths, and total death for each female were transformed to the Freeman-Tukey arc sine form, and then
subjected to the t-test to compare values for each treatment with the control value. Fertility indices analyzed were as followes: copulating ability
(copulating males/total males), impregnating ability (impregnating males/total males), copulated ratio (copulated females/total females), pregnant
ratio (pregnant F/total F), and pregnancy efficiency (pregnant F/copulated F).
X2 test: for fertility indices to compare the values of each treatment group with the control value. It was tested whether the fertility indices were
linearly related to arithmetic or logarithmic dose. The proportion of F with one or more dead implantations in each treatment group was compared
with the control value in the same way as for the fertility indices, by X2 and Armitage’s X2 tests.
Regression analysis: to determine whether the average number of implantations per F was related to the arithmetic or logarithmic dose.
The rank sum test: to compare the number of resorbed fetuses per F and the average number of skeletal variations per litter for each treatment
group with the control value. An analysis of variance across 6 weeks was made for the average number of total implantations per F, preimplantation
losses per F (using the Freeman-Tukey arc sine transformation), total deaths per F (using the arc sine transformation), and the ratio of deaths to the total implantations per F (using the arc sine transformation)
Reproductive indices:
copulating ability and impregnating ability of males and copulated ratio, pregnant ratio, and pregnancy efficiency of females
Offspring viability indices:
no information

Results and discussion

Results: P0 (first parental animals)

General toxicity (P0)

Clinical signs:
not examined
Body weight and weight changes:
not specified
Food consumption and compound intake (if feeding study):
not specified
Organ weight findings including organ / body weight ratios:
not specified
Gross pathological findings:
not specified
Histopathological findings: non-neoplastic:
not specified
Other effects:
not specified

Reproductive function / performance (P0)

Reproductive function: oestrous cycle:
not specified
Reproductive function: sperm measures:
not specified
Reproductive performance:
effects observed, treatment-related

Details on results (P0)

A dose of 10 mg/kg bw/d (as CdCl2) for 9 wk did not affect the fertility of male rats in dominant lethal tests. The five analysed fertility indices (copulating ability and impregnating ability of males and copulated ratio, pregnant ratio, and pregnancy efficiency of females) did not reveal a difference withcontrol rats when males were mated with untreated females. When treated males were mated with females having undergone the same Cd treatment, adverse effects were observed in the 10 mg/kg bw/d group on number of copulation and pregnancies, on the number of implants and live fetuses (NOAEL: 1 mg Cd/kg bw/d).

Parental data: The numbers of copulating and pregnant females decreased at 10 mg Cd/kg bw/d. Consequently, the average numbers of total implantations and live fetuses per female decreased, and the average number of resorbed fetuses increased significantly at the highest dose (10 mg/kg bw/d). The higher the dose levels, the smaller the average number of total implantations and live fetuses, although the differences from the control were not significant in the two lower dose groups (0.1 and 1.0 mg/kg bw/d). For details see table 1 under remarks on results.

In dominant lethal tests, five fertility indices (copulating ability and impregnating ability of males and copulated ratio, pregnant ratio, and pregnant efficiency of females) were statistically analyzed for significant differences from the control values. No difference was observed, indicating that the administration of Cd at oral dose levels of less than 10 mg/kg bw/d for 9 wk did not affect fertility of male rats.

The number of impregnated F1 and the average numbers of corpora lutea, total implantations, preimplantation losses, live fetuses, late deaths, and total deaths per F did not show any significant differences from the control values. The analysis of variance across 6 wk for total implantations, preimplantation losses, total deaths, and the ratio of deaths to the total implantations also showed no differences compared with the control values. The proportions of F with one or more dead implantations in all treatment groups were similar to each other. 

Effect levels (P0)

open allclose all
Dose descriptor:
NOAEL
Effect level:
ca. 1 mg/kg bw/day
Sex:
female
Dose descriptor:
NOAEL
Remarks:
reproductive
Effect level:
1 mg/kg bw/day
Sex:
female
Dose descriptor:
LOAEL
Remarks:
reproductive
Effect level:
10 mg/kg bw/day
Sex:
female
Basis for effect level:
other: >50% fewer copulating and pregnant females

Results: F1 generation

General toxicity (F1)

Clinical signs:
not specified
Mortality / viability:
mortality observed, treatment-related
Body weight and weight changes:
effects observed, treatment-related
Sexual maturation:
not specified
Organ weight findings including organ / body weight ratios:
not specified
Gross pathological findings:
effects observed, treatment-related
Histopathological findings:
not specified

Details on results (F1)

Fetal data:

Gross anomalies-
Body weight, body length, and tail length of fetuses from the highest dose showed significant decreases in both males and females, compared to the control values. These fetuses were small and yellowish in color, indicative of anemia and malnutrition. The average weight of the placentas increased significantly in the highest dose. Even in the two lower dose groups placental weight was greater than the control value in both M and F (supposed to be adaptative hypertrophy).

Visceral anomalies-
No marked changes were detected. Hydronephrosis was observed in one rat in each group. Since the number of fetuses examined in the highest dose group was small, the percentage of this anomaly was high, but no definite conclusion can be drawn form these data.

Skeletal anomalies-
As mentioned in table 1, the fetuses from the highest dose group were small and showed growth retardation which was reflected in delayed ossification of the sternebrae and the small number of ossified caudal vertebrae.

Effect levels (F1)

open allclose all
Dose descriptor:
NOAEL
Generation:
F1
Effect level:
ca. 1 mg/kg bw/day
Sex:
male/female
Dose descriptor:
LOAEL
Generation:
F1
Effect level:
10 mg/kg bw/day
Sex:
male/female
Basis for effect level:
other: delayed ossification, decreased body weight

Overall reproductive toxicity

Reproductive effects observed:
not specified

Any other information on results incl. tables

TOXIC RESPONSE/EFFECTS BY DOSE LEVEL: 
Parental data: see repeat dose tox test

- Table 1: Fertility

Dose (mg/kg/

d)

n° of animals

copulating

Pregnant

corpora lutea1

total implants1

live fetuses1

macerated

resorbed

0

14

14

11

15.2 (2.0)

14.7 (2.0)

14.2 (2.0)

0

0.55

0.1

13

13

10

14.2 (2.0)

13.9 (1.7)

13.9 (1.7)

0

0.70

1.0

13

12

12

15.5 (1.8)

13.6 (1.8)

13.1 (2.3)

0

0.50

10.0

13

5

5

13.6 (1.5)

10.6 (3.1)**

7.2 (2.4)

0.8

2.6*

 

 

 

 

 

 

 

 

 

1Mean and (standard deviation)

* significantly different from the control at P < 0.05

**: significantly different from the control at P < 0.01


- Data on fetuses: gross anomalies:

Table 2: Male fetuses

dose (mg Cd/kg/d)

0

0.1

1.0

10.0

N° of fetuses

71

73

73

15

Body weight (g)

3.63 (0.10)

3.58 (0.23)

3.52 (0.27)

2.41 (0.29)**

Body length (mm)

39.1 (0.4)

39.2 (0.9)

93.0 (1.1)

35.2 (1.0)**

Tail length (mm)

13.8 (0.3)

13.7 (0.3)

14.0 (0.5)

12.3 (1.1)*

Placenta (mg)

502 (25)

524 (60)

530 (49)

548 (46)*

 

Table 3: Female fetuses

dose (mg Cd/kg/d)

0

0.1

1.0

10.0

N° of fetuses

85

59

84

21

Body weight (g)

3.48 (0.16)

3.40 (0.25)

3.37 (0.23)

2.32 (0.23)**

Body length (mm)

38.5 (0.5)

39.4 (3.4)

38.2 (0.8)

34.3 (1.2)**

Tail length (mm)

14.1 (0.3)

14.0 (0.5)

14.3 (0.3)

12.5 (0.9)*

Placenta (mg)

479 (30)

501 (78)

500 (57)

554 (73)*

Figures are given as mean and (standard deviation)

* significantly different from the control at p < 0.05

** significantly different from the control at p < 0.01


Table 4: Data on fetuses: visceral anomalies

 

dose (mg Cd/kg/d)

0

0.1

1.0

10.0

N° of fetuses

53

44

54

12

Hemorrhage in facial area (%)

3 (5.7)

0

4 (7.5)

0

Hemorrhage in adrenal (%)

3 (5.7)

1 (2.2)

0

0

Hemorrhage in abdominal cavity (%)

1 (1.9)

2 (4.5)

0

0

Dilatation of renal pelvis (%)

7 (13.2)

9 (20.0)

7 (13.0)

1 (8.3)

hydronephrosis

1 (1.9)

1 (2.2)

1 (1.9)

1 (8.3)

 


Table 5: Data on fetuses: skeletal anomalies

dose (mg Cd/kg/d)

0

0.1

1.0

10.0

N° of fetuses

103

88

104

24

Delayed ossificationof:

 

 

 

 

Os parietale (%)

0

6 (6.8)

0

0

Os interparietale (%)

3 (2.9)

13 (14.8)

3 (2.8)

2 (8.3)

Os sphenoides (%)

5 (4.9)

12 (13.6)

2 (1.9)

4 (16.7)

Cervical vertebrae (%)

0

0

0

2 (8.3)

Sternebrae

 

 

 

 

1st(%)

0

1 (1.1)

0

2 (8.3)

2nd(%)

0

1 (1.1)

2 (1.9)

6 (25.0)

3rd(%)

0

1 (1.1)

4 (3.8)

0

4th(%)

1 (1.0)

3 (3.4)

5 (4.8)

7 (28.0)

5th(%)

33 (32.0)

37 (42.0)

38 (36.5)

21 (87.5)**

6th(%)

26 (25.2)

28 (31.8)

22 (21.2)

24 (100)**

Cervical rib(%)

0

0

0

3 (12.5)

14thrib(%)

11 (107)

14 (15.9)

1 (1.0)

0

N° of caudal vertebrae

4.21+/- 0.40

3.87+/- 0.33

4.09+/-0.47

2.13+/-1.18**

* significantly different from the control at P < 0.05

** significantly different from the control at P < 0.01



Applicant's summary and conclusion

Conclusions:
Rats at the dose of 10 mg/kg bw/d exhibited toxic signs. These rats showed reduced fertility but neither teratogenicity nor dominant lethality was observed. As both sexes were treated it was not clear from the fertility studies which sex was more affected. However the negative outcome of dominant lethal tests (treated M and untreated F) suggested that females were more strongly affected than males.
According to the authors, the effects seen in the fertility studies can perhaps be explained mainly in terms of two factors: anemia and hormonal
imbalance. This study with acceptable test design and study reporting appears to be the most critical study related to effects on fertility.
Executive summary:

A study was conducted to evaluate the effects of the test material on the reproductive performance of parental rats and fetal development.

Males and females within each treatment group were mated 6 d/wk for 3 wk and the test material was administered at 0, 0.1, 1.0 and 10.0 mg Cd/kg bw/d during the mating period. Pregnant females were administered Cd during gestation and killed on Day 20 of gestation for developmental test (fetal examination). Nonpregnant females were killed after a total administration period of 13 wk. Additionally after a total of 9 wk of administration, males were mated with 2 virgin females per male per week for 6 wk. Pregnant females were killed on Day 13 of gestation for dominant lethal tests (examination of the numbers of corpora lutea, live fetuses, early deaths (no remnants of fetuses), and late deaths (remnants of fetuses)). One week after the cessation of dominant lethal tests, which represents a recovery period of 50 d, male rats were killed and examined.

A dose of 10 mg/kg bw/d (as CdCl2) for 9 wk did not affect the fertility of male rats in dominant lethal tests. The five analysed fertility indices (copulating ability and impregnating ability of males and copulated ratio, pregnant ratio, and pregnancy efficiency of females) did not reveal a difference with control rats when males were mated with untreated females. When treated males were mated with females having undergone the same Cd treatment, adverse effects were observed in the 10 mg/kg/day group on number of copulation and pregnancies, on the number of implants and live fetuses (NOAEL: 1 mg Cd/kg bw/d).