Registration Dossier

Administrative data

Key value for chemical safety assessment

Effects on fertility

Description of key information

Based on the results of a GLP-compliant study similar to OECD 416, the NOAEL for parental P1-P3 generation was 5000 ppm (500 mg/kg bw) and the NOAEL for F1-F3 offspring was 1000 ppm (100 mg/kg bw).

Link to relevant study records
Reference
Endpoint:
three-generation reproductive toxicity
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
comparable to guideline study with acceptable restrictions
Qualifier:
equivalent or similar to guideline
Guideline:
OECD Guideline 416 (Two-Generation Reproduction Toxicity Study)
Deviations:
yes
Remarks:
Additional third generation, missing assay parameters: lenght of estrus cycle, vaginal opening, preputial separation, sperm parameters, anogenital distance
Principles of method if other than guideline:
The effects of the test substance on reproduction were studied in a three-generation reproduction study in albino rats. The chemical was administered in the diet at levels of 0, 1000, 5000, and 10000 ppm (0, 100, 500 and 1000 mg/kg bw/d, respectively). Criteria used to evaluate for compound effect in the parental animals were mortality, clinical signs, body weight, food consumption, reproduction indices, and gross and microscopic pathology. Criteria evaluated in the offspring were gross appearance, survival, body weight, male pup percentages, gross pathology and kidney weight data.
GLP compliance:
yes
Remarks:
(Hazleton Laboratories America, Inc.)
Limit test:
no
Specific details on test material used for the study:
- Name of test material (as cited in study report): Caprolactam
- 3 lots of caprolactam were used. In order to achieve a homogeneous blend, equal amounts of each lot were ground until homogeneous and used to prepare each batch of test diet.
Species:
rat
Strain:
Fischer 344
Sex:
male/female
Details on test animals or test system and environmental conditions:
TEST ANIMALS
- Source: Charles River Breeding Laboratories, Inc., Wilmington, Massachusetts
- Weight at study initiation: (P) Males: 88-133 g, Females: 67-104 g


ENVIRONMENTAL CONDITIONS
- Temperature (°C): 17-29
- Humidity (%): 31-68
- Photoperiod (hrs dark / hrs light): 12/12
- Housing in non-breeding period: individually in wire-mesh cages
- Housing in breeding period: one male and two females per breeding cage
- Diet: ad libitum
- Water: ad libitum
- Acclimation period: 2 weeks
Route of administration:
oral: feed
Details on exposure:
PREPARATION OF DOSING SOLUTIONS:
- The compound and feed were mixed in a Hobart mixer which at small amounts gave a better blend. Fresh diets were prepared and presented weekly.
- fresh diest were prepared weekly and reserve samples were retained from each mixed batch and sent to the sponsor for analysis.
Details on mating procedure:
Mating phase of first (P1), second (P2) and third (P3) generation:
10 males and 20 females were mated / group.
- M/F ratio per cage: 1/2
- Length of cohabitation: 2 weeks
- each parental generation was subjected to two breeding phases. The second breeding occurred 7-13 days after the sacrifice of the first litter of
offspring.



Analytical verification of doses or concentrations:
yes
Duration of treatment / exposure:
Treatment phase:
10 weeks-premating exposure period (males and females of P1).
Following mating the treatement phase was 10 weeks.
Dosing of test substance continuously in the diet throughout three successive generations.

Frequency of treatment:
daily
Details on study schedule:
- parental animals were 10 males and 20 females per dose group in each generation. They were treated 10 weeks before mating.

- F1-generations:
F1a
(1) gross necropsy on approx. 1/3 of the pups
(2) remaining pups were sacrificed without necropsy
F1b
(1) 10males and 20 females / group were selected for P2 generation
(2) gross necropsy on approx. 1/3 of the pups
(3) remaining pups were sacrificed without necropsy

- F2-generations:
F2a
(1) gross necropsy on approx. 1/2 of the pups
(2) remaining pups were sacrificed without necropsy
F2b
(1) 10males and 20 females / group were selected for P3 generation
(2) gross necropsy on approx. 1/3 of the pups
(3) remaining pups were sacrificed without necropsy

- F3-generations:
F3a
(1) gross necropsy on approx. 1/3 of the pups
(2) remaining pups were sacrificed without necropsy
F3b
(1) gross necropsy on approx. 1/2 of the pups
(2) remaining pups were sacrificed without necropsy

- Each litter was observed and the number of live and dead pups (by sex), individual body weights and any evidence of abnormality were recorded on days 1, 7 and 21 of lactation . At Day 7, litters were culled by random card draw to eight pups (equal number per sex where possible).
- The second (P2) and third (P3) parenteral animals were selected by random card draw from each group of F1b and F2b litters for assignment to the same treatment group as described above.


Remarks:
Doses / Concentrations:
1000, 5000 and 10000 ppm
Basis:
nominal in diet
Remarks:
Doses / Concentrations:
100, 500 and 1000 mg/kg bw
Basis:
other: calculated based on a conversion factor of 10 (Derelanko, M.J., The Toxicologist's Pocket Handbook, 2nd Ed., p.29, 2008).
Remarks:
Doses / Concentrations:
79, 355, 726 mg/kg bw/day in females; 86, 422, 878 mg/kg bw/day in males
Basis:
actual ingested
No. of animals per sex per dose:
10 males and 20 females
Control animals:
yes, concurrent vehicle
Parental animals: Observations and examinations:
CAGE SIDE OBSERVATIONS: Yes
- Time schedule: daily
- Cage side observations: any gross signs of toxicity and pharmacologic effects


BODY WEIGHT: Yes
- Time schedule for examinations: initially and at week 4 and 10


FOOD CONSUMPTION AND COMPOUND INTAKE (if feeding study):
- Food consumption for each animal determined: Yes for weeks 4 and 10
Postmortem examinations (parental animals):
P1 animals were sacrificed and complete gross necropsies were performed.
The P2 and P3 animals were sacrificed and discarded without necropsy.
All parental animals that died on study were necropsied and gross observations recorded.
Postmortem examinations (offspring):
Gross necropsy was performed of 1/3 (F1a/b, F2b, F3a/b) or 1/2 (F3b) of the offspring.
The kidneys from each necropsied F3b pup were weighed and kidney/body weight ratios were determined.
Statistics:
Parental body weights and food consumption values, and offspring body weights from each generation of the control group, were compared statistically to data of the treated groups of the same sex by Bartlett's test for homogeneity of variance and the one-way classification analyses of variance (ANOVA).
If there were significant results, a multiple pairwise comparison procedure or Scheffe's multiple pairwise comparison procedure was used to compare the group mean values. Reproduction and viability indices were analyzed using the chi-square method.
The percentage of male pups at each interval was analyzed using Wilcoxon's non-parametric comparison of group means. The individual litter was considered as the experimental unit in all calculations.
The F3b kidney weight data for the control group were compared statistically to the data for the caprolactam treated groups of the same sex by Bartlett's test for homogeneity of variance, and then by a one-way classification analysis of variance (ANOVA) if the variance proved to be homogeneous. If the variances were heterogeneous, a log10 transformation was performed, followed by Bartlett's test. If the log10 transformation could not remove the variance heterogeneity, a loge transformation of the original data, followed by Bartlett's test, was performed. If homogeneity could not be achieved, the ANOVA of the non-transformed data was completed. If the ANOVA of homogeneous data was significant, Scheffe's multiple pairwise comparison
procedure was used to compare the group mean values. If the ANOVA of heterogeneous data was significant, Games and Howell's multiple pairwise
comparison procedure was used to compare the group mean values. All analyses were evaluated at 5% probability (one-tailed) level.
Clinical signs:
no effects observed
Description (incidence and severity):
No treatment-related clinical signs were noted within the parental generations.
Dermal irritation (if dermal study):
not examined
Mortality:
mortality observed, non-treatment-related
Description (incidence):
Within the P1 animals, one low- and two high-dose females died during Week 1 of the ten-week growth period. One P2 control male was found dead following the growth period and one P3 male was found dead just prior to the F3b breeding. These deaths were noted randomly by test group, sex and parenteral generation, and were not attributed to the administration of the test substance
Body weight and weight changes:
effects observed, treatment-related
Description (incidence and severity):
Significantly (p<=0.05) lower body weights were noted in both the high-dose P2 and P3 males and females at weeks 0, 4, and 10. In addition, generally lower body weights were noted in the mid-dose group of both sexes of the P2 animals, and the male P3 animals at the same intervals, with the mid-dose P2 males at Week 4 being significant.
Food consumption and compound intake (if feeding study):
effects observed, treatment-related
Description (incidence and severity):
A similar effect on food consumption was observed although the response in the males appeared to be more pronounced than in the females. Significantly lower food consumption values were noted in the high-dose P1 females at week 10 (17 %), the mid-dose P2 males at weeks 4 and 10 (10-15 %), the high-dose P2 and P3 males at weeks 4 and 10 (9-18%), and the high-dose P2 and P3 females at week 10 (7-10%).
Food efficiency:
not examined
Water consumption and compound intake (if drinking water study):
not examined
Ophthalmological findings:
not examined
Haematological findings:
not examined
Clinical biochemistry findings:
not examined
Urinalysis findings:
not examined
Behaviour (functional findings):
not examined
Immunological findings:
not examined
Organ weight findings including organ / body weight ratios:
not examined
Histopathological findings: non-neoplastic:
effects observed, treatment-related
Description (incidence and severity):
Compound-related histopathologic findings noted in the high-dose P1 animals consisted of a slight increase in the severity of spontaneous nephropathies.
This nephropathy was characterized by the presence of regenerative tubule epithelium, mononuclear inflammatory cells and occasional dilated tubules
containing proteinaceous casts. In addition, dilated tubules containing granular casts were noted in three of the rats. Kidney sections from rats in the control group as well as the low- and mid-dose treated groups revealed slightly less severe nephropathy and were essentially comparable in appearance between the control and treated rats.
Histopathological findings: neoplastic:
not examined
Other effects:
not specified
Reproductive function: oestrous cycle:
not examined
Reproductive function: sperm measures:
not examined
Reproductive performance:
no effects observed
Description (incidence and severity):
The pregnancy and fertility indices were comparable between the treated and control groups for each filial generation, and no dose-related trends were apparent.
Key result
Dose descriptor:
NOAEL
Effect level:
500 mg/kg bw/day
Sex:
male/female
Basis for effect level:
other: body weight, spontaneous nephropathies
Clinical signs:
no effects observed
Description (incidence and severity):
No treatment-related clinical signs were noted within the parental generations.
Dermal irritation (if dermal study):
not examined
Mortality:
mortality observed, non-treatment-related
Description (incidence):
Within the P1 animals, one low- and two high-dose females died during Week 1 of the ten-week growth period.
Body weight and weight changes:
no effects observed
Description (incidence and severity):
No effects were observed.
Food consumption and compound intake (if feeding study):
effects observed, treatment-related
Description (incidence and severity):
Significantly lower food consumption values were noted in the high-dose P1 females at week 10 (17 %)
Food efficiency:
not examined
Water consumption and compound intake (if drinking water study):
not examined
Ophthalmological findings:
not examined
Haematological findings:
not examined
Clinical biochemistry findings:
not examined
Urinalysis findings:
not examined
Behaviour (functional findings):
not examined
Immunological findings:
not examined
Organ weight findings including organ / body weight ratios:
not examined
Gross pathological findings:
no effects observed
Description (incidence and severity):
no treatment related effects were observed
Neuropathological findings:
not examined
Histopathological findings: non-neoplastic:
effects observed, treatment-related
Description (incidence and severity):
Compound-related histopathologic findings noted in the high-dose P1 animals consisted of a slight increase in the severity of spontaneous nephropathies.
This nephropathy was characterized by the presence of regenerative tubule epithelium, mononuclear inflammatory cells and occasional dilated tubules
containing proteinaceous casts. In addition, dilated tubules containing granular casts were noted in three of the rats. Kidney sections from rats in the control group as well as the low- and mid-dose treated groups revealed slightly less severe nephropathy and were essentially comparable in appearance between the control and treated rats.
Histopathological findings: neoplastic:
not examined
Other effects:
not examined
Reproductive function: oestrous cycle:
not examined
Reproductive function: sperm measures:
not examined
Reproductive performance:
not examined
Key result
Dose descriptor:
NOAEL
Effect level:
500 mg/kg bw/day
Sex:
male/female
Basis for effect level:
other: body weight, spontaneous nephropathies
Clinical signs:
no effects observed
Description (incidence and severity):
No treatment-related clinical observations were noted in any of the three filial generations.
Dermal irritation (if dermal study):
not examined
Mortality / viability:
no mortality observed
Description (incidence and severity):
The live birth, neonatal survival and weaning survival indices were generally comparable between the treated and control groups for each filial generation, and no dose-related trends were noted.
Body weight and weight changes:
effects observed, treatment-related
Description (incidence and severity):
Lower mean body weights were observed in male and female pups at the two highest dose levels in all filial generations. The response was dose-related, with significant differences (P ≤ 0.05) noted more frequently in the pups receiving a dose of 10000 ppm.
Food consumption and compound intake (if feeding study):
not examined
Food efficiency:
not examined
Water consumption and compound intake (if drinking water study):
not examined
Ophthalmological findings:
not examined
Haematological findings:
not examined
Clinical biochemistry findings:
not examined
Urinalysis findings:
not examined
Sexual maturation:
not examined
Anogenital distance (AGD):
not examined
Nipple retention in male pups:
not examined
Organ weight findings including organ / body weight ratios:
no effects observed
Description (incidence and severity):
No significant differences were noted in the mean relative kidney weights (Table 6).
Gross pathological findings:
no effects observed
Description (incidence and severity):
no treatment related effects were observed
Histopathological findings:
not examined
Other effects:
no effects observed
Description (incidence and severity):
SEX (OFFSPRING): No treatment-related effects were noted in evaluation of the percentage of male pups.
Behaviour (functional findings):
not examined
Developmental immunotoxicity:
not examined
Key result
Dose descriptor:
NOAEL
Generation:
F1
Effect level:
100 mg/kg bw/day
Sex:
male/female
Basis for effect level:
body weight and weight gain
Reproductive effects observed:
not specified

Table 1. Summary of maternal reproduction indeces, offspring survival, and growth from the first generation.  

 

F1a

F1b

Dose [ppm]

0

1000

5000

10000

0

1000

5000

10000

Parental reproduction indeces

#females

20

19

20

18

20

19

20

18

#pregnant females

19

15

19

14

19

17

18

16

Pregnancy rate [%]

95

79

95

77

95

89.5

90

88.9

Male fertility rate [%]

100

100

100

100

100

90

100

100

Offspring indeces

Day 1 #pups/litter

9.8 +/-2.2

8.7 +/-2.5

9.1 +/-2.0

9.2 +/-2.5

10.6 +/-4.2

8.8 +/-3.1

10.3 +/-2.8

9.7 +/-3.3

Day 1 live birth index [%]

98.7

100

100

93.8

99.5

100

99.1

100

Day 7 survival index [%]

100

96.2

100

93.9

99

98.6

98.6

97.9

Day 21 survival index [%]

100

99.2

100

91.1

100

100

99.3

100

% males day 1

44.9

46.9

50.9

55.7

51.8

50

46.5

52.9

Mean offspring body weights

Males day 1

5.91 +/-0.89

5.87 +/-0.71

6.07 +/-0.77

4.86 +/-0.36**

5.49 +/-0.73

5.77 +/-1.05

5.22 +/-0.52

5.25 +/-0.66

females day 1

5.56 +/-0.73

5.61 +/-0.68

5.59 +/-0.75

4.53 +/-1.56

5.4 +/-0.71

5.36 +/-0.58

4.79 +/-0.35**

4.86 +/-0.66

Males day 7

10.77 +/-1.28

11.49 +/-2.22

10.78 +/-1.4

8.76 +/-1.69**

11.02 +/-1.17

11.68 +/-1.96

9.94 +/-1.28

9.03 +/-1.55**

females day 7

10.25 +/-1.40

11.11 +/-2.06

10.31 +/-1.09

8.9 +/-1.06**

10.62 +/-1.23

11.09 +/-1.68

9.28 +/-1.17

8.75 +/-1.45**

Males day 21

29.65 +/-2.66

30.46 +/-4.4

27.65 +/-2.98

22.79 +/-1.28**

31.58 +/-2.46

31.48 +/-4.09

27.97 +/-3.8**

25.03 +/-3.35**

females day 21

28.08 +/-2.3

29.11 +/-3.56

26.62 +/-3.05

22.22 +/-1.69**

29.82 +/-2.68

30.08 +/-3.64

25.79 +/-2.26**

24.63 +/-3.28**

**p≤0.05

Table 2. Summary of maternal reproduction indeces, offspring survival, and growth from the second generation.  

 

F2a

F2b

Dose [ppm]

0

1000

5000

10000

0

1000

5000

10000

Parental reproduction indeces

#females

20

20

20

20

20

20

20

20

#pregnant females

16

19

15

17

15

20

18

17

Pregnancy rate [%]

80

95

75

85

75

100

90

85

Male fertility rate [%]

100

100

100

100

100

100

100

100

Offspring indeces

Day 1 #pups/litter

10 +/-2.7

9.2 +/-3.6

9.5 +/-2.8

8.4 +/-2.2

10.3 +/-2.7

10.7 +/-3.2

8.6 +/-3.4

7.8 +/-3.4

Day 1 live birth index [%]

100

98.2

98.1

100

100

99.6

100

98.2

Day 7 survival index [%]

100

100

99.3

100

99.1

99.2

99.2

91.1

Day 21 survival index [%]

100

99.3

100

99.3

100

100

99.3

93.4

% males day 1

54.7

52.6

50.3

53.4

49.3

52.1

47.9

46.6

Mean offspring body weights

Males day 1

5.54 +/-0.7

5.6 +/-0.65

5.46 +/-0.627

4.99 +/-0.94

5.56 +/-0.49

5.48 +/-0.57

5.5 +/-0.59

5.12 +/-0.7

females day 1

5.35 +/-0.61

5.18 +/-0.4

5.09 +/-0.6

4.67 +/-0.78**

5.32 +/-0.47

5.15 +/-0.41

5.16 +/-0.6

4.74 +/-0.63**

Males day 7

11.48 +/-1.85

10.79 +/-1.16

10.7 +/-1.23

9.33 +/-0.82**

10.83 +/-1.37

10.67 +/-1.65

10.24 +/-1.47

9.29 +/-1.79

females day 7

10.87 +/-1.46

10.24 +/-1.03

10.27 +/-1.18

8.75 +/-0.99**

10.26 +/-1.25

9.84 +/-1.84

9.75 +/-1.41

8.76 +/-1.76

Males day 21

31.95 +/-3.46

31.07 +/-2.94

29.69 +/-2.86

24.36 +/-3.26**

31.89 +/-2.39

32.1 +/-3.2

29.47 +/-2.51**

25.03 +/-4.94**

females day 21

30.14 +/-2.99

29.47 +/-2.02

27.73 +/-2.12

22.97 +/-2.51**

30.46 +/-1.97

29.43 +/-3.28

28.32 +/-2.74

23.49 +/-4.43**

**p≤0.05

Table 3. Summary of maternal reproduction indeces, offspring survival, and growth from the third generation.  

 

F3a

F3b

Dose [ppm]

0

1000

5000

10000

0

1000

5000

10000

Parental reproduction indeces

#females

20

20

20

20

20

20

20

20

#pregnant females

14

15

17

16

17

17

15

15

Pregnancy rate [%]

70

75

85

80

85

85

75

83.3

Male fertility rate [%]

90

100

100

100

100

100

100

100

Offspring indeces

Day 1 #pups/litter

9.4 +/-2.6

9.8 +/-3.6

10.8 +/-2.8

9.5 +/-1.6

9 +/-4.5

9.9 +/-4.3

9.1 +/-3.1

7.7 +/-1.9

Day 1 live birth index [%]

99.5

100

100

100

99.5

100

98

96.2

Day 7 survival index [%]

94.1

90.9

98.2

99.3

96.8

94.8

90.5

99.3

Day 21 survival index [%]

96.5

99.1

96.3

99.3

99.3

93.4

98.1

100

% males day 1

47.1

47.3

45.9

56.7

53.3

52.8

57.8

51.9

Mean offspring body weights

Males day 1

5.9 +/-0.51

5.43 +/-0.45

5.27 +/-0.72**

5.17 +/-0.62**

5.79 +/-1.01

5.47 +/-0.92

5.59 +/-1.01

4.93 +/-0.68

females day 1

5.44 +/-0.35

5.15 +/-0.4

4.91 +/-0.78

4.73 +/-0.57**

5.36 +/-0.71

5.04 +/-0.67

5.35 +/-0.95

4.62 +/-0.42

Males day 7

10.29 +/-1.64

10.49 +/-1.7

9.85 +/-1.78

9.09 +/-1.74

10.85 +/-2.22

10.36 +/-2.95

10. 4 +/-2.31

8.86 +/-1.46

females day 7

9.81 +/-1.5

9.89 +/-1.85

9.63 +/-1.79

8.75 +/-1.79

10.28 +/-1.68

9.77 +/-2.47

9.96 +/-2.35

8.11 +/-1.28**

Males day 21

29.96 +/-3.07

30.28 +/-4.35

27.18 +/-2.65**

23.03 +/-3.82**

31.22 +/-3.63

30.46 +/-5.67

28.3 +/-5.08

23.77 +/-4.32**

females day 21

27.61 +/-2.56

28.01 +/-3.36

26.21 +/-2.44

22.49 +/-3.56**

29.22 +/-2.71

28.75 +/-4.41

27.41 +/-4.42

21.96 +/-3.33**

**p≤0.05

Table 4. Mean terminal body weights, kidney weights and kidney/body weight ratiosa, of selected F3b, pups from a three-generation reproduction study of Caprolactam in rats.

Dose (ppm)

No. examined

Terminal body weight (g)

Kidney weight (g)

Kidney/body weight ratio

Males

0

25

30.80±3.571

0.456±0.1163

1.481±0.3432

1000

31

28.84±40.50

0.448±0.1402

1.545±0.4001

5000

26

27.62**±3.060

0.402±0.1045

1.453±0.3094

10000

25

22.32**±2.174

0.318**±0.0378

1.426±0.1416

Females

0

21

27.95±2.397

0.424±0.1248

1.513±0.3946

1000

20

29.40±4.604

0.419±0.0710

1.428±0.1492

5000

20

27.35±4.030

0.427±0.1126

1.555±0.3029

10000

26

21.31±2.739

0.310**±0.476

1.455±0.1083

aEach value shown is the mean± the standard deviation

** p<0.05 vs control

Conclusions:
Based on the results, the NOAEL for parental P1-P3 generation was 5000 ppm (500 mg/kg bw) and the NOAEL of F1-F3 offspring was 1000 ppm (100 mg/kg bw).
Executive summary:

The effects of the test substance on reproduction were studied in a three-generation reproduction study in albino rats.  The chemical was administered in the diet at levels of 0, 1000, 5000, and 10000 ppm (0, 100, 500 and 1000 mg/kg bw/d, respectively). Criteria used to evaluate for compound effect in the parental animals were mortality, clinical signs, body weight, food consumption, reproduction indices, and gross and microscopic pathology. Criteria evaluated in the offspring were gross appearance, survival, body weight, male pup percentages, gross pathology and kidney weight data.

The effects on mean body weight, mean food consumption and the group increases in the severity of nephropathy, accompanied by the presence of granular casts in some animals, are considered to be related to the administration of the test substance. Based on the results, the NOAEL for parental P1-P3 generation was 5000 ppm (500 mg/kg bw).

The pregnancy and fertility indices were comparable between the treated and control groups for each filial generation and no dose-related trends were apparent, thus the NOAEL for fertility was 1000 mg/kg bw. The only effect observed in offspring were lower mean body weights in male and female pups at the two highest dose levels in all filial generations, the the NOAEL of F1-F3 offspring was 1000 ppm (100 mg/kg bw).

Effect on fertility: via oral route
Endpoint conclusion:
no adverse effect observed
Dose descriptor:
NOAEL
100 mg/kg bw/day
Species:
rat
Effect on fertility: via inhalation route
Endpoint conclusion:
no study available
Effect on fertility: via dermal route
Endpoint conclusion:
no study available
Additional information

In a three-generation study F344 rats were continuously fed with the test substance at dose levels of ca. 100, 500, 1000 mg/kg bw throughout three successive generations (Hazleton et al., 1981). Following the 10 weeks premating exposure periods, no treatment-related clinical signs of toxicity, changes in reproductive performance or gross-pathological findings were noted within the parental generations. Compound-related findings were mainly related to body weight loss (significant in the high-dose group only). Histopathologic findings noted in the high-dose P1 animals consisted of a slight increase in the severity of spontaneous nephropathies, occasionally accompanied by granular casts in 3 of 10 male animals. Based on these findings, the NOAEL for the parental P1-P3 generations was identified as 500 mg/kg bw.

Pregnancy and fertility indices were comparable between treated and control groups for each filial generation and no dose-related trends were apparent, thus the NOAEL for fertility was 1000 mg/kg bw.

The offspring data revealed no treatment-related effects with respect to gross appearance, gross pathology, survival, number of pups, and percentage of male pups or kidney weight. The only effect observed in offspring were lower mean body weights in male and female pups at the two highest dose levels in all filial generations, the NOAEL of F1-F3 offspring was 1000 ppm (100 mg/kg bw). Summarized no adverse effect on reproductive organs or function were found in this 3-generation study with rats.

These findings were supported by the 103-month Combined Chronic Toxicity / Carcinogenicity Study with Fischer rats (NTP 1982). No effects on reproductive organs (testes weights as well as information on gross and microscopic pathology for testes, prostate, ovaries, and uteri) were observed at the highest dose tested (375 mg/kg bw/day).

Effects on developmental toxicity

Description of key information

Based on the results of a GLP-compliant study similar to OECD 414, the NOAEL for the maternal rats has been found to be 100 mg/kg bw/day due to body weight gain.  The NOAEL for the fetuses has been found to be 500 mg/kg bw/day for fetotoxicity (mean fetal body weight and viability) and 1000 mg/kg bw/day for teratogenicity (the highest dose tested).

A second GLP-compliant study similar to OECD 414 revealed that the NOAEL for maternal animals was 150 mg/kg bw/day due to mortality and body weight changes. The NOAEL for the fetuses has been found to be 50 mg/kg bw/day for fetotoxicity (fetal weight) and greater than 250 mg/kg bw/day for teratogenicity.

Link to relevant study records

Referenceopen allclose all

Endpoint:
developmental toxicity
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
study well documented, meets generally accepted scientific principles, acceptable for assessment
Qualifier:
equivalent or similar to guideline
Guideline:
OECD Guideline 414 (Prenatal Developmental Toxicity Study)
Deviations:
yes
Remarks:
Older study reports
Principles of method if other than guideline:
This study was designed to evaluate the developmental toxicity potential of the test substance in rats.
The test material was administered by oral intubation on days 6 through 15 of gestation to each of three groups of twenty pregnant female rats of the Fischer 344 strain at levels of 100, 500, and 1000 mg/kg bw, respectively. A fourth group of twenty pregnant rats received only the vehicle (distilled water) and served as the control group. Criteria evaluated for evidence of compound effect were maternal body weight and body weight changes, food consumption, clinical observations, survival, gross pathology, implantation and resorption efficiencies, and offspring viability and development.
GLP compliance:
yes
Remarks:
(Hazleton Laboratories America, Inc.)
Limit test:
no
Specific details on test material used for the study:
- Name of test material (as cited in study report): Caprolactam
- Physical state: white crystalline solid
- Analytical purity: approximately 100 %
Species:
rat
Strain:
Fischer 344
Details on test animals or test system and environmental conditions:
TEST ANIMALS
- Source: Microbiological Associates, Walkerville, Maryland
- Weight at study initiation: 149-205 g
- Diet (e.g. ad libitum): Purina Laboratory Chow
- Water (e.g. ad libitum): Tap water
- Acclimation period: 20 days

Route of administration:
oral: gavage
Vehicle:
water
Details on exposure:
PREPARATION OF DOSING SOLUTIONS: Appropriate amounts of the test material were dissolved in distilled water on a weight-per-volume basis and administered by oral intubation (amount based on individual body weight, dosing factor 10 ml/kg bw) from day 6 through day 15 of gestation.
Details on mating procedure:
- Impregnation procedure: cohoused
- If cohoused:
- M/F ratio per cage: 1/2
- Proof of pregnancy: sperm in vaginal smear referred to as day 0 of pregnancy
Duration of treatment / exposure:
day 6-15 of gestation
Frequency of treatment:
daily
Duration of test:
day 20 of gestation
Dose / conc.:
0 mg/kg bw/day
Dose / conc.:
100 mg/kg bw/day
Dose / conc.:
500 mg/kg bw/day
Dose / conc.:
1 000 mg/kg bw/day
No. of animals per sex per dose:
20
Control animals:
yes, concurrent no treatment
Maternal examinations:
CAGE SIDE OBSERVATIONS: Yes
- Time schedule: daily


DETAILED CLINICAL OBSERVATIONS: Yes
- Time schedule: during day 6-20 of gestation


BODY WEIGHT: Yes
- Time schedule for examinations: on days 0, 6, 11, 15, and 20 of gestation


FOOD CONSUMPTION AND COMPOUND INTAKE (if feeding study): Yes
- Food consumption for each animal determined: Yes on days 6, 11, 15, and 20 of gestation


POST-MORTEM EXAMINATIONS: Yes
- Sacrifice on gestation day 20
- Organs examined:

Ovaries and uterine content:
The ovaries and uterine content was examined after termination: Yes
Examinations included:
- Number of corpora lutea: Yes
- Number of implantations: Yes
- Number of early resorptions: Yes
- Number of late resorptions: Yes
Fetal examinations:
- External examinations: Yes
- Soft tissue examinations: Yes
- Skeletal examinations: Yes
Clinical signs:
effects observed, treatment-related
Description (incidence and severity):
Clinical observations made during the treatment and post treatment periods that were noted in the treated groups: urine stains, a rough hair coat, a red discharge from the vagina, a bloody crust on or about the eyes, mouth, and/or nose, a thin and/or hunched appearance, and/or depression.
Dermal irritation (if dermal study):
not examined
Mortality:
mortality observed, treatment-related
Description (incidence):
The maternal survival rate was statistically significantly lower in the high-dose group when compared with the control. Nine high-dose females (six pregnant, three not pregnant) were found dead during the treatment phase of this study.
Body weight and weight changes:
effects observed, treatment-related
Description (incidence and severity):
The mean body weight values of the high dose group on day 15 and 20 of gestation and the mean body weight changes of the mid- and high dose groups for the days 6-11 and 6-15 were statistically significantly (p<0.05) lower than the control values at these intervals (Table 1). The percent body weight change in the mid dose group during the treatment period 6-11 and 6-15 were -0.8 and 5.2, respectively, in comparison to 6.2 and 13.4 in control group. Similarly in the high dose group, the percent body weight change were -2.7 and 2.3, respectively.
Food consumption and compound intake (if feeding study):
effects observed, treatment-related
Description (incidence and severity):
The mean food consumption was significantly lower (p<0.05) in the mid- and high-dose groups.
Food efficiency:
not examined
Water consumption and compound intake (if drinking water study):
not examined
Ophthalmological findings:
not examined
Haematological findings:
not examined
Clinical biochemistry findings:
not examined
Urinalysis findings:
not examined
Behaviour (functional findings):
not examined
Immunological findings:
not examined
Organ weight findings including organ / body weight ratios:
not examined
Gross pathological findings:
not examined
Neuropathological findings:
not examined
Histopathological findings: non-neoplastic:
not examined
Histopathological findings: neoplastic:
not examined
Other effects:
effects observed, treatment-related
Description (incidence and severity):
The pregnancy rates were slightly higher in the low- and mid-dose groups (80 and 75%) than in the control (60%). The mean implantation efficiencies were slightly lower in the low-and high-dose groups than in the control (Table 2). The mean incidence of resorptions was statistically significantly (p<0.05) higher than the control value in the high-dose group (Table 2).
Dose descriptor:
NOAEL
Effect level:
100 mg/kg bw/day (actual dose received)
Basis for effect level:
other: maternal toxicity
Fetal body weight changes:
effects observed, treatment-related
Description (incidence and severity):
The mean body weight of the male fetuses in the treated groups was slightly lower than that of the control group, and the mean body weight of the female fetuses in the mid-and high-dose groups was slightly lower than that of the control group. The difference in the mean body weight was remarkable only in the high dose males (10% low) and females (15% low), however the difference was not statistically significant.
Reduction in number of live offspring:
effects observed, treatment-related
Description (incidence and severity):
The mean incidence of fetal death was comparable for all groups, and the mean incidence of fetal viability was lower in the high-dose group than in the control group.
Changes in sex ratio:
not examined
Changes in litter size and weights:
not examined
Changes in postnatal survival:
not examined
External malformations:
not examined
Skeletal malformations:
no effects observed
Description (incidence and severity):
No treatment-related visceral or skeletal anomalies were observed. Skeletal variants were observed in each group with the mid- and high dose groups having a higher incidence of skeletal variants than the control group. In the control group the variants included incomplete ossification of the skull (supraoccipital or interparietal), a nonfused vertebral column (centra), and/or extra ribs. The variants observed in the treated groups included incomplete ossification of the skull (supraoccipital and/or interparietal), incomplete and/or malfused sternebrae, extra ribs, and/or nonfused and/or incomplete ossification of the vertebral column (centra). No statistically significant differences were noted in these data.
Visceral malformations:
no effects observed
Description (incidence and severity):
No treatment-related visceral or skeletal anomalies were observed. Skeletal variants were observed in each group with the mid- and high dose groups having a higher incidence of skeletal variants than the control group. In the control group the variants included incomplete ossification of the skull (supraoccipital or interparietal), a nonfused vertebral column (centra), and/or extra ribs. The variants observed in the treated groups included incomplete ossification of the skull (supraoccipital and/or interparietal), incomplete and/or malfused sternebrae, extra ribs, and/or nonfused and/or incomplete ossification of the vertebral column (centra). No statistically significant differences were noted in these data.
Other effects:
effects observed, treatment-related
Description (incidence and severity):
The mean fetal lengths were slightly lower (below 10 %) in the high dose-group than in the controls.
Dose descriptor:
NOAEL
Effect level:
500 mg/kg bw/day (actual dose received)
Basis for effect level:
other: fetotoxicity
Dose descriptor:
NOAEL
Effect level:
1 000 mg/kg bw/day (actual dose received)
Basis for effect level:
other: teratogenicity
Abnormalities:
not specified
Developmental effects observed:
not specified

Table 1. Mean maternal body weights and body weight changesa

Body weights

Days

Dose level (mg/kg bw)

0

100

500

1000

 

 

Mean weight (g)

0

167.2

174.4

170.8

168.0

6

176.7

184.4

180.7

176.8

11

187.6

192.9

179.3

172.0

15

200.3

204.4

190.1

180.8s-

20

234.6

233.9

225.3

208.8s-

Mean change (g)

Pre-treatment period

0-6

9.5

10.5

9.9

8.8

Treatment period

6-11

10.9

8.0

-1.4s-

-4.8s-

Treatment period

11-15

12.7

11.5

10.8

8.8

Total Treatment period

6-15

23.6

19.5

9.4s-

4.0s-

Post-treatment period

15-20

34.3

29.5

35.2

28.0

Total study period

0-20

67.4

59.5

54.5

40.8

Percent change (%)

Pre-treatment period

0-6

5.7

6.0

5.8

5.2

Treatment period

6-11

6.2

4.3

-0.8

-2.7

Treatment period

11-15

6.8

6.0

6.0

5.1

Total Treatment period

6-15

13.4

10.5

5.2

2.3

Post-treatment period

15-20

17.1

14.4

18.5

15.5

Total study period

0-20

40.3

34.1

31.9

24.3

aOnly data from pregnant rats surviving to Day 20 of gestation were included in calculations of the mean values

S-:Statistically significantly (p<0.05) lower than the control value.

Table 2. Summary of the Ovarian, Uterine, and Litter Dataa

Parameters

Dose level (mg/kg bw)

0

100

500

1000

Number of females mated

20

20

20

20

Number of rats pregnant

12

16

15

11

Pregnancy rate (%)

30.0

80.0

75.0

55.0

Number of pregnant rats surving to day 20

12

16

15

5

Maternal survival rate (%)

100.0

100.0

100.0

45.5

Mean number of:

Corpora lutea

11.8

12.9

11.7

12.8

Implantations

9.6

8.5

9.6

8.6

Resorptions

0.4

0.5

0.3

3.2

Fetuses- Dead

0.0

0.0

0.0

0.0

Fetuses- Live

9.2

8.6

9.3

5.4

Indices calculated on aper litter per group basis:

Mean implantation efficiency (%)

81.78

70.56

81.11

67.92

Mean incidence of resorption (efficiency) (%)

4.64

5.24

3.27

41.34

Mean incidence of fetal death (%)

0.00

0.00

0.00

0.00

Mean incidence of fetal viability (%)

95.36

94.76

96.39

58.66

aOnly data from pregnant rats surviving to Day 20 of gestation were included in calculations of the mean values

S-:Statistically significantly (p<0.05) lower than the control value.

S+:Statistically significantly (p<0.05) higher than the control value.

Conclusions:
The NOAEL for the maternal rats has been found to be 100 mg/kg bw/day due to body weight gain. The NOAEL for the fetuses has been found to be 500 mg/kg bw/day for fetotoxicity (mean fetal body weight and viability) and 1000 mg/kg bw/day for teratogenicity (the highest dose tested).
Executive summary:

This study was designed to evaluate the developmental toxicity potential of the test substance in rats. The test material was administered by oral intubation on days 6 through 15 of gestation to each of three groups of twenty pregnant female rats of the Fischer 344 strain at levels of 100, 500, and 1000 mg/kg bw, respectively. A fourth group of twenty pregnant rats received only the vehicle (distilled water) and served as the control group. Criteria evaluated for evidence of compound effect were maternal body weight and body weight changes, food consumption, clinical observations, survival, gross pathology, implantation and resorption efficiencies, and offspring viability and development. The NOAEL for the maternal rats has been found to be 100 mg/kg bw/day due to body weight gain. The NOAEL for the fetuses has been found to be 500 mg/kg bw/day for fetotoxicity (mean fetal body weight and viability) and 1000 mg/kg bw/day for teratogenicity (the highest dose tested).

Endpoint:
developmental toxicity
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
study well documented, meets generally accepted scientific principles, acceptable for assessment
Qualifier:
equivalent or similar to guideline
Guideline:
OECD Guideline 414 (Prenatal Developmental Toxicity Study)
Deviations:
no
Principles of method if other than guideline:
The test substance was evaluated for developmental toxicity in rabbits by the oral route. Three groups of 25 inseminated female rabbits were gavaged with the test substance at dose levels of 50, 150 or 250 mg/kg bw/day from day 6 to day 28 of gestation. A control group was treated in an identical manner except that it was dosed with the vehicle distilled water. A group treated with 6-Aminonicotinamide (6-AN) at 3 mg/kg bw on day 9 of gestation was included in the study as a positive control group. Criteria evaluated for evidence of compound related effects were maternal body weight and body weight changes, food consumption, clinical observations survival, gross pathology, implantation and resorption efficiencies, and offspring viability and development.
GLP compliance:
yes
Remarks:
(Bio-Research Laboratories, Ltd.)
Limit test:
no
Specific details on test material used for the study:
- Name of test material (as cited in study report): Caprolactam
- Physical state: a coarse, white, crystalline powder
- Lot/batch No.: SPL Nos. 8185-4A, B and C; Batch No. MA NO 179A
Species:
rabbit
Strain:
New Zealand White
Details on test animals or test system and environmental conditions:
TEST ANIMALS
- Source: Dutchland Laboratories Inc., Swampbridge, Pennsylvania
- Age at study initiation: 22-24 weeks
- Weight at study initiation: 3.0-4.8 Kg
- Diet (e.g. ad libitum): Purina Certified Rabbit Chow No. 5322
- Water (e.g. ad libitum): tap water
- Acclimation period: 3 weeks


ENVIRONMENTAL CONDITIONS
- Temperature (°C): 15-23.9
- Humidity (%): 33-86
- Photoperiod (hrs dark / hrs light): 12/12
Route of administration:
oral: gavage
Vehicle:
water
Details on exposure:
PREPARATION OF DOSING SOLUTIONS: The solutions of Caprolactam were prepared by dissolving Caprolactam in distilled water. The dosing solutions were made fresh each week by direct dissolution. The dose solutions were kept refrigerated at circa 5°C when not in use.

VEHICLE
- Amount of vehicle (if gavage): The volume of dose solution given was 2 mL/kg bw and was based on each rabbit's body weight on day 6 of gestation
Analytical verification of doses or concentrations:
yes
Details on mating procedure:
- Impregnation procedure: artificial insemination
Duration of treatment / exposure:
day 6-28 of gestation
Frequency of treatment:
daily
Duration of test:
29 days
Dose / conc.:
50 mg/kg bw/day
Dose / conc.:
150 mg/kg bw/day
Dose / conc.:
250 mg/kg bw/day
No. of animals per sex per dose:
25
Control animals:
yes, concurrent vehicle
Maternal examinations:
CAGE SIDE OBSERVATIONS: Yes
- Time schedule: twice-daily examination of the condition of the rabbits was performed during the period from day 6 to 29 of gestation.

BODY WEIGHT: Yes
- Time schedule for examinations: on days 0, 6, 9, 12, 15, 18, 21, 24, 27 and 29 of gestation


POST-MORTEM EXAMINATIONS: Yes
- Sacrifice on gestation day 29
Ovaries and uterine content:
The ovaries and uterine content was examined after termination: Yes
Examinations included:
- Gravid uterus weight: Yes
- Number of implantations: Yes
- Number of early resorptions: Yes
- Number of late resorptions: Yes
Fetal examinations:
- External examinations: Yes: all per litter
- Soft tissue examinations: Yes: all per litter
- Skeletal examinations: Yes: all per litter
- Head examinations: Yes: all per litter
Clinical signs:
not examined
Dermal irritation (if dermal study):
not examined
Mortality:
mortality observed, treatment-related
Description (incidence):
Four rabbits in the 250 mg/kg bw/day group died during the treatment period. One control rabbit died on day 29 of gestation. There were no deaths at the 50 and 150 mg/kg bw/day level. Three of this four rabbits had convulsion immediately after gavage and died within 35 min. The fourth 250 mg/kg bw/day rabbit was found dead on day 28 of gestation. Four high-dose rabbits had convulsions immediately after treatment. All except 1 of these does subsequently died. In addition, 2 high dose rabbits had rapid breathing at 10 minutes post-dosing.
Body weight and weight changes:
effects observed, treatment-related
Description (incidence and severity):
In the high dose group the overall weight gain between day 6 and day 29 of gestation was significantly decreased (P<0.05). For the corrected weight gain (weight gain day 6 to day 29 of gestation minus weight of gravid uterus), there was a significantly (P<0.05) greater weight loss in the mid-dose group (Table 1). The corrected body weights (body weight on day 29 of gestation minus weight of gravid uterus) for the test substance-treated group were not significantly different from control values.
Food consumption and compound intake (if feeding study):
effects observed, treatment-related
Description (incidence and severity):
Decreased food intake, decreased fecal volume (both qualitatively assessed) and the presence of areas of alopecia were the most common incidental findings. There were no adverse effects from treatment on clinical conditions in rabbits in the 50 or 150 mg/kg bw or 6-An group.
Food efficiency:
not examined
Water consumption and compound intake (if drinking water study):
not examined
Ophthalmological findings:
not examined
Haematological findings:
not examined
Clinical biochemistry findings:
not examined
Urinalysis findings:
not examined
Behaviour (functional findings):
not examined
Immunological findings:
not examined
Organ weight findings including organ / body weight ratios:
not examined
Gross pathological findings:
not examined
Neuropathological findings:
not examined
Histopathological findings: non-neoplastic:
not examined
Histopathological findings: neoplastic:
not examined
Other effects:
not examined
Number of abortions:
not examined
Pre- and post-implantation loss:
not examined
Total litter losses by resorption:
not examined
Early or late resorptions:
not examined
Dead fetuses:
not examined
Changes in pregnancy duration:
not examined
Changes in number of pregnant:
not examined
Other effects:
not examined
Dose descriptor:
NOAEL
Effect level:
150 mg/kg bw/day (actual dose received)
Basis for effect level:
other: maternal toxicity
Fetal body weight changes:
effects observed, treatment-related
Description (incidence and severity):
The fetal weights of the 150 and 250 mg/kg bw/day and 6-AN dose groups were decreased significantly (p<0.05, p<0.01 and p<0.01, respectively) (Table 2).
Reduction in number of live offspring:
no effects observed
Description (incidence and severity):
The numbers of corpera lutea, live and dead fetuses, resorptions, the sex ratio and the pre- and post-implantation losses were not significantly different among the test and control groups.
Changes in sex ratio:
not examined
Changes in litter size and weights:
not examined
Changes in postnatal survival:
not examined
External malformations:
not examined
Skeletal malformations:
no effects observed
Description (incidence and severity):
The incidence of major malformations was unaffected by treatment with the test substance. The overall incidence of minor skeletal anomalies was unaffected in the test substance-treated groups. The incidence of fetuses with either unilateral or bilateral thirteenth ribs (common skeletal variant) was significantly increased at the 250 mg/kg bw/day dose level. Treatment with 6-AN resulted in significantly (P < 0.01) increased incidences of minor skeletal anomalies.
Visceral malformations:
effects observed, non-treatment-related
Description (incidence and severity):
The incidence of major malformations was unaffected by treatment with the test substance. A statistically significant increase (P<0.05) in the incidence of fetuses with minor visceral anomalies, resulting from an increase in the incidence of fetuses with absence of the posterior azygos lobe of the lungs, occurred at the 50 mg/kg bw/day dose level. This was not considered to be related to the test substance treatment. Treatment with 6-AN resulted in significantly (P < 0.01) increased incidences of minor visceral anomalies .
Other effects:
not specified
Dose descriptor:
NOAEL
Effect level:
50 mg/kg bw/day (actual dose received)
Basis for effect level:
other: fetotoxicity
Dose descriptor:
NOAEL
Effect level:
> 250 mg/kg bw/day (actual dose received)
Basis for effect level:
other: teratogenicity
Abnormalities:
not specified
Developmental effects observed:
not specified

Table 1.Group mean (S.D) body weight gains (G) of pregnant rabbits with live fetuses

Dose groups

Interval (days of gestation)

0-6

6-9

9-12

12-15

15-18

18-21

21-24

24-27

27-29

6-29

VC (2 ml/kg bw)

180.5 (92.40)

39.0 (50.02)

40.5 (49.56)

66.4 (59.00)

-10.5 (98.76)

47.2 (70.00)

48.8 (89.55)

6.7 (104.40)

19.6 (29.28)

257.8 (169.73)

CAP (50 mg/kg bw)

128.9 (87.22)

6.3 (86.51)

30.3 (83.60)

47.4 (59.40)

-15.5 (73.74)

37.4 (83.28)

50.6 (62.26)

-16.0 (90.81)

16.1 (54.71)

156.5 (218.83)

CAP (250 mg/kg bw)

159.4 (73.40)

-113.7a(72.65)

-23.9 (64.86)

1.8 (110.16)

-4.5 (92.19)

53.5 (108.55)

88.1 (72.92)

30.5 (90.88)

17.9 (83.18)

49.7a(173.54)

CAP (150 mg/kg bw)

163.9 (92.40)

-27.5a(62.50)

16.4 (72.27)

54.4 (106.72)

27.4 (92.98)

64.6 (99.07)

28.7 (105.63)

-27.7 (80.02)

-25.6 (72.69)

110.5 (249.24)

6-AN (3 mg/kg bw)

153.4 (94.28)

79.8 (38.89)

-54.3a(92.09)

114.5 (141.66)

38.5 (70.75)

37.3 (81.40)

16.0 (106.13)

13.3 (54.86)

8.3 (50.38)

253.5 (194.11)

a p < 0.05

VC: vehicle control

 

Table 2.Group mean (S.D.) uterine findings per litter

Dose groups

Litter weight (g)

Pre- implantation loss (%)

Post- implantation loss (%)

Sex ratio (M/F)

No. of resorptions

Mean fetal weight (g)

Early

Middle

Late

Total

VC (2 ml/kg bw)

334.1 (115.87)

15.48 (23.662)

21.26 (27.774)

0.7

1.0 (1.41)

0.1 (0.36)

0.4 (0.94)

1.6 (1.50)

44.16 (8.401)

CAP (50 mg/kg bw)

300.1 (104.24)

16.91 (25.071)

11.38 (22.147)

1.1

0.9 (2.14)

0.0 (0.00)

0.1 (0.33)

1.1 (2.14)

41.81 (7.316)

CAP (250 mg/kg bw)

294.9 (124.28)

9.72 (8.457)

21.69 (32.670)

0.9

1.2 (2.62)

0.1 (0.26)

1.1 (2.34)

2.3 (3.70)

38.88 (4.829)

CAP (150 mg/kg bw)

347.3 (100.39)

6.15 (7.861)

7.63 (14.229)

0.9

0.5 (1.17)

0.1 (0.23)

0.2 (0.54)

0.8 (1.36)

38.77a(5.675)

6-AN (3 mg/kg bw)

319.1 (90.31)

12.05 (14.109)

13.64 (20.707)

1.2

0.7 (1.65)

0.2 (0.60)

0.6 (1.19)

1.5 (2.40)

37.48b(2.735)

ap<0.05

bp<0.01

VC: vehicle control

Conclusions:
The NOAEL for maternal animals has been found to be 150 mg/kg bw/day due to mortality and body weight changes. The NOAEL for the fetuses has been found to be 50 mg/kg bw/day for fetotoxicity (fetal weight) and greater than 250 mg/kg bw/day for teratogenicity.
Executive summary:

The test substance was evaluated for developmental toxicity in rabbits by the oral route. Three groups of 25 inseminated female rabbits were gavaged with the test substance at dose levels of 50, 150 or 250 mg/kg bw/day from day 6 to day 28 of gestation. A control group was treated in an identical manner except that it was dosed with the vehicle distilled water. A group treated with 6-Aminonicotinamide (6-AN) at 3 mg/kg bw on day 9 of gestation was included in the study as a positive control group. Criteria evaluated for evidence of compound related effects were maternal body weight and body weight changes, food consumption, clinical observations survival, gross pathology, implantation and resorption efficiencies, and offspring viability and development.

Maternal toxicity in terms of mortality was observed in pregnant rabbits treated with the test substance at a dose of 250 mg/kg bw/day. Also at the 250 mg/kg bw/day dose level, adverse clinical findings and adverse effects upon weight gain occurred. Fetotoxicity was evidenced by lower fetal weights at the 150 and 250 mg/kg bw/day levels, and an increased incidence of thirteenth ribs was observed at the 250 mg/kg bw/day dose level. Neither embryotoxicity nor teratogenicity occurred. The NOAEL for maternal animals has been found to be 150 mg/kg bw/day due to mortality and body weight changes. Based on these results, the NOAEL for the fetuses has been found to be 50 mg/kg bw/day for fetotoxicity (fetal weight) and greater than 250 mg/kg bw/day for teratogenicity.

Effect on developmental toxicity: via oral route
Endpoint conclusion:
no adverse effect observed
Dose descriptor:
NOAEL
50 mg/kg bw/day
Species:
rat
Effect on developmental toxicity: via inhalation route
Endpoint conclusion:
no study available
Effect on developmental toxicity: via dermal route
Endpoint conclusion:
no study available
Additional information

In a Developmental toxicity study performed according to the current OECD guideline 414, 20 F344 rats/group were gavaged with dose levels of 100, 500 and 1000 mg/kg/d bw on days 6-15 of gestation. The maternal survival rate was statistically lower in the high-dose group when compared with the control. Nine high-doses females were found dead during the treatment phase of this study. Clinical observations such as urine stains, rough hair coat, red discharge from the vagina, bloody crust on eyes, mouth and nose, and thin and/or hunched appearance were observed in dose dependent manner in all treated groups.

The mean body weight values of the high dose group were significantly (p<0.05) lower than in controls on days 15 (10%) and 20 (11%) of gestation. Furthermore, the mean body weight changes of the mid- and high-dose groups for the days 6-11 and 6-15 were significantly (p<0.05) lower than the control values at these intervals. These effects on body weights were accompanied by significantly lower values of mean food consumption in the mid- and high-dose groups. In these maternally toxic doses, a slight reduction in fetal body weight was observed. The mean number of corpora lutea and implantations per group were not affected by treatment, but the mean implantation efficiencies were slightly reduced in the high-dose group. No treatment-related visceral or skeletal anomalies were observed.

Based on these results in rats, the NOAEL for maternal toxicity was identified as 100 mg/kg bw/d, for embryotoxicity as 500 mg/kg bw/d and for teratogenicity as 1000 mg/kg bw/d.

 

In an analogous developmental toxicity study (Bio-Research, 1983) with New Zealand White Rabbits, 25 animals/group were gavaged with dose levels of 50, 150 and 250 mg/kg bw on days 6-28 of gestation. In the high dose group 4 rabbits died during the treatment period. Also exclusively in the high dose group, adverse clinical findings were observed. The absolute weight gain between day 6 and 29 was decreased in the high dose group, whereas the corrected body weight gain (body weight gain day 6-29 minus weight of gravid uterus) was significantly decreased in mid dose animals.

Fetotoxicity was evidenced by lower fetal weights at the mid and high dose groups, and an increased incidence of thirteenth ribs was observed in the high dose group. Neither embryotoxicity nor teratogenicity occurred. Based on these findings in rabbits, the NOAEL for maternal toxicity and fetotoxicity was identified as 150 and 50 mg/kg bw, respectively. No teratogenicty was observed with the highest dose tested (NOAELtera 250 mg/kg bw/day).

 

In a BASF study (1978), no signs of maternal toxicity and fetotoxicity were observed in rats after dosing 166 mg test substance/kg bw by oral-gavage. Thus, the NOAEL for maternal, fetal and developmental toxicity was above 166 mg/kg bw/d. 

 

Toxicity to reproduction: other studies

Description of key information

no study available

Justification for classification or non-classification

The test substance is not warranted for classification and labelling according to Directive 67/548/EEC Annex I and

according to the EU Classification, Labelling and Packaging of Substances and Mixtures (CLP) Regulation (EC) No. 1272/2008.

Additional information