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Toxicological information

Toxicity to reproduction

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Administrative data

Endpoint:
screening for reproductive / developmental toxicity
Remarks:
based on test type (migrated information)
Type of information:
migrated information: read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
key study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Acceptable, well-documented and cited in the peer-reviewed regulatory agency.

Data source

Reference
Reference Type:
publication
Title:
Unnamed
Year:
2004

Materials and methods

Test guideline
Qualifier:
according to
Guideline:
OECD Guideline 421 (Reproduction / Developmental Toxicity Screening Test)
Deviations:
not applicable
GLP compliance:
yes
Limit test:
no

Test material

Reference
Name:
Unnamed
Type:
Constituent
Type:
Constituent
Details on test material:
- Name of test material (as cited in study report): N-ethylmorpholine
- Analytical purity: Equal or more than 99 %
- Impurities (identity and concentrations): 0.05% as moisture
- Lot/batch No.: 2901P0

Test animals

Species:
rat
Strain:
other: Crj:CD(SD)IGS
Sex:
male/female
Details on test animals and environmental conditions:
Four weeks old Crj:CD(SD)IGS rats bought from Charles River Japan, Inc. They were put in quarantine and acclimatization for 7 d before use.

Administration / exposure

Route of administration:
oral: gavage
Vehicle:
water
Details on exposure:
The test solution was prepared and diluted to dosing concentrations by injection solvent every week. They were kept in a refrigerator. The diluted solution was also confirmed to be stable for 8 d.
Duration of treatment / exposure:
Males: 42 d
Females: From 14 d before mating to Day 3 of lactation
Frequency of treatment:
Once daily
Doses / concentrations
Remarks:
Doses / Concentrations:
0 (vehicle), 50, 150, 500 mg/kg bw/day
Basis:
nominal conc.
No. of animals per sex per dose:
13/sex/dose
Control animals:
yes, concurrent vehicle

Examinations

Parental animals: Observations and examinations:
CAGE SIDE OBSERVATIONS: Yes

DETAILED CLINICAL OBSERVATIONS: Yes

BODY WEIGHT: Yes
Oestrous cyclicity (parental animals):
Yes
Sperm parameters (parental animals):
Parameters examined in P male parental generations: Testis weight, epididymis weight, histopathological examination of reproductive organs
Litter observations:
PARAMETERS EXAMINED
The following parameters were examined in F1 offspring: Number and sex of pups, stillbirths, live births, viability index
Postmortem examinations (parental animals):
Terminal killing: Males at Day 43; females at Day 4 of lactation.
Postmortem examinations (offspring):
Necropsy was perfomed.
Statistics:
Statistical analysis of offspring was carried out using the litter as the experimental unit. Bartlett's test of homogeneity of variance was used to determine if the groups had equivalent at the 5% level of significance. If variance was equivalent, the groups were compared by one-way analysis of variance. If significant
differences were found, Dunnett's test was performed. If the groups did not have equivalent variances, the Kruskal-Wallis test was used to assess the overall effects. Whenever significant differences were noted, Dunnett-type test was performed. Mann-Whitney U-test or Fisher's exact test was also used.
Reproductive indices:
Copulation index and fertility index
Offspring viability indices:
Gestation index , implantation index, delivery index , birth index , live birth index , sex ratio and viability index

Results and discussion

Results: P0 (first parental generation)

General toxicity (P0)

Clinical signs:
effects observed, treatment-related
Body weight and weight changes:
effects observed, treatment-related
Food consumption and compound intake (if feeding study):
effects observed, treatment-related
Organ weight findings including organ / body weight ratios:
no effects observed
Histopathological findings: non-neoplastic:
no effects observed

Reproductive function / performance (P0)

Reproductive function: oestrous cycle:
no effects observed
Reproductive function: sperm measures:
no effects observed
Reproductive performance:
no effects observed

Details on results (P0)

No deaths were found in males of any group. One female at 500 mg/kg bw/day showed tremor and died on Day 2 of lactation. In clinical signs, salivation was observed in males and females at 150 mg/kg bw/day and higher. Decrease in body weight gain and food consumption were detected in male at 500 mg/kg bw/day and females at 150 mg/kg bw/day and higher. Absolute and relative weights of testes and epididymides were not affected by dosing. Necropsy and histopathological examination of reproductive organs revealed no abnormalities related to dosing. No adverse effects on estrous cycle, copulation, fertility, gestation length, gestation index or number of corpora lutea were found. No significant changes were observed in numbers of implantations, pups live pups and in indexes for implantation, delivery, birth and live birth were detected.

Effect levels (P0)

open allclose all
Dose descriptor:
NOAEL
Remarks:
(for reproductive toxicity)
Effect level:
500 mg/kg bw/day (nominal)
Based on:
test mat.
Sex:
male/female
Basis for effect level:
other: see 'Remark'
Dose descriptor:
NOAEL
Remarks:
(for systemic toxicity)
Effect level:
150 mg/kg bw/day (nominal)
Based on:
test mat.
Sex:
male/female
Basis for effect level:
other: Based on observed clinical signs such as salivation as well as decrease in body weight and food consumption at higher doses.

Results: F1 generation

General toxicity (F1)

Clinical signs:
no effects observed
Mortality / viability:
no mortality observed
Body weight and weight changes:
no effects observed
Gross pathological findings:
no effects observed

Details on results (F1)

There were no treatment-related changes in the body weight external appearance, general conditions or necropsy findings in offspring of rats.

Overall reproductive toxicity

Reproductive effects observed:
not specified

Any other information on results incl. tables

Table 1. Body weight changes of rats treated orally with N-ethylmorpholine in preliminary reproduction toxicity screening test:

Dose (mg/kg/ bw/day)

0

50

150

500

Male
No. of animals  

13

13

13

 

13

Terminal body weight (g)

+/-S.D.

497.0    
40.4       

494.0    

30.9      

488.0    

38.9       

457.5*

31.7

Female
No. of animals  

13

13

13

 

13

Days 14 of administration (g)
+/-S.D.

266.5    

13.1       

263.6    

15.7       

263.4    

17.8       

259.5

17.5

No. of animals  

12

12

12

12

Days 20 of pregnancy (g)

+/-S.D.

428.5    

33.1       

423.2    

29.8       

410.6    

27.2

386.1*  

42.1

No. of animals

12

12

12

12

Days 4 of lactation (g)

+/-S.D.

345.6    

22.8

338.4

26.9

330.1

19.3       

329.7

24.5

Significant difference from control group; *p=<0.05,**p=<0.01

Table 2. Food consumption of rats treated orally with N-ethylmorpholine in preliminary reproduction toxicity screening test

Dose (mg/kg/ bw/day)

0

50

150

500

Male
No. of animals  

13

13

13

 

13

Days of administration (g)

1-2

+/-S.D.

27.8       

1.9

26.9

2.3

25.4

3.7

21.3**

2.7

7-8

+/-S.D.

25.1

1.9         

25.8

1.5

25.3

2.8

22.1**

1.7

14-15    

+/-S.D.

27.1

2.9         

27.7

8.2

26.6

2.9

24.3*

3.2

29-30

+/-S.D.

28.7

2.4         

29.5

2.1

28.0

2.7

24.2**

1.7

35-36

+/-S.D.

29.9

7.5         

26.7

3.3

27.7

3.0

27.2

6.4

41-42    

+/-S.D.

29.6       

3.3         

29.4

3.4

28.9

4.1

26.2*

2.0

Female
No. of animals  

13

13

13

13

Days of administration (g)

1-2

+/-S.D.

20.7

1.9         

18.5

3.5

16.6**

3.4

16.5**

3.7

7-8         

+/-S.D.

19.7

3.7         

19.4

3.9

20.2

2.9

19.9

3.5

14-15

+/-S.D.

19.9

3.7         

20.4

2.6

19.7

2.3

19.4

1.8

No. of animals

12

12

12

12

Days of pregnancy (g)

0-1

+/-S.D.

21.0       

2.6         

21.1

1.9

19.4

2.7

18.4*

2.9

7-8         

+/-S.D.

28.9

3.6         

28.5

3.0

25.5*

3.4

23.2**

3.2

14-15    

+/-S.D.

28.6

3.4

26.8

2.8

26.3

2.0

24.7*

4.3

20-21    

+/-S.D.

19.3

3.5         

21.0

2.4

20.8

4.0

18.7

2.5

No. of animals

12

12

12

9

Days 4 of lactation (g)

3-4

+/-S.D.

47.1

6.7         

49.4

4.6

43.3

4.3

41.4       

8.8

Significant difference from control group; *p=<0.05,**p=<0.01

Table 3. Estrous cycle and reproductive performance in rats treated orally with N-ethylmorpholine in preliminary reproduction toxicity screening test

Dose (mg/kg/ bw/day)

0

50

150

500

Estrous cycle

Type of cycle during treatment period

 4-day cycle

13

13

12

12

 4,5-day cycle

0

0

1

1

Length of estrous cycle in days
+/-S.D.

4.0

0.0                        

4.0

0.0

4.0

0.1

4.0

0.1

Reproductive performance

Number of mated pairs

13

13

13

13

Number of copulated pairs

13

13

12

12

Copulation index (%)

100.0

100.0

92.3

92.3

Number of pregnant animals

12

12

12

11

Fertility index (%)

92.3

92.3

100.0

91.7

Pairing days until copulation
 +/-S.D.

2.3

1.1

2.2

1.1

3.3

1.7

2.6

1.3

Frequency of vaginal estrus
 +/-S.D.

1.0

0.0         

1.0

0.0

1.1

0.3

1.0

0.0

Copulation index = (Number of copulated pairs/Number of mated pairs) X 100
Fertility index = (Number of pregnant animals/Number of copulated pairs) X 100


Table 4. Summary of development of pups from dams treated orally with N-ethylmorpholine in preliminary reproduction toxicity screening test

Dose (mg/kg/ bw/day)

0

50

150

500

Number of pregnant females

12

12

12

11

Gestation index (%)

100.0

100.0

100.0

90.9

Gestation length in days

+/-S.D.

22.7

0.5         

22.3

0.7

22.3

0.5

22.8

0.6

Number of corpora lutea

+/-S.D.

16.2

2.0         

16.9

1.8

15.7

1.9

16.0

3.0

Number of implantation sites

+/-S.D.

15.6

2.6         

16.1

1.7

14.8

1.8

13.1

4.7

Implantation index (%)

+/-S.D.

95.9

7.4

95.2

4.9

94.9

6.1

80.6

26.6

Day 0 of lactation

Number of pups born

+/-S.D.

14.2       

2.8

15.1

1.2

13.8

1.6

11.4

4.9

Delivery index (%)

+/-S.D.

90.6

9.3         

94.1

6.0

93.1

7.7

84.6

15.8

Number of pups alive

+/-S.D.

13.7

2.9

15.0

1.3

13.7

1.7

10.0

5.4

Birth index (%)

+/-S.D.

87.4

9.7         

93.6

5.7

92.5

8.0

71.2

32.7

Live birth index (%)

+/-S.D.

96.5

5.6

99.4

1.9

99.4

2.2

83.5

35.6

Sex ratio on day 0 (%)

+/-S.D.

52.4

13.2

47.9

8.0

48.9

12.6

54.2

26.3

Day 4 of lactation

Number of pups alive

+/-S.D. 

13.6

2.8

15.0

1.3

13.5

1.7

11.6

3.9

Viability index (%)

+/-S.D.

99.5

1.7         

100.0

0.0

98.8

2.8

98.1

3.8

Sex ratio on day 4 (%)

+/-S.D. 

52.6

13.1

47.9

8.0

49.5

12.6

58.5

25.9

Gestation index = (Number of females with live pups/ Number of pregnant females) X 100
Implantation index = (Number of implantation sites/ Number of corpora lutea) X 100
Delivery index = (Number of pups born/Number of implantation sites) X 100
Birth index = (Number of live pups on day 0/Number of implantation sites) X 100
Live birth index = (Number of live pups on day 0/Number of pups born) X 100
Sex ratio = (Number of male live pups/Number of female live pups) X 100
Viability index = (Number of live pups on day 4/Number of live pups on day 0)

Applicant's summary and conclusion

Conclusions:
Based on the absence of any adverse effects of the read-across substance, ethylmorpholine on reproductive and developmental parameter, the NOAEL for reproductive and developmental toxicity is considered to be 500 mg/kg bw/day. Further, based on clinical signs and decreased body weight gain and food consumption, the LOAEL and NOAEL for general toxicity in parent animals are considered to be 150 and 50 mg/kg bw/day, respectively.
Executive summary:

The toxicity to reproduction of the read-across substance, 4-ethylmorpholine was tested in a reproduction / developmental toxicity screening test according to the OECD Guideline 421 in compliance with GLP.

Drj:CD(SD)IGD rats (13 animals/sex/dose) were given test substance by gavage at 0 (vehicle: water), 50, 150 or 500 mg/kg bw/day. Males were dosed for a total of 42 d beginning 14 d before mating. Females were dosed from 14 d before mating to Day 3 of lactation throughout the mating and pregnancy period.

No deaths were found in males of any group. One female at 500 mg/kg bw/day died on Day 2 of lactation. Tremor was observed in the female which died, and transient salivation after dosing was observed in males and females at 150 mg/kg bw/day and higher. Decrease in body weight gain accompanied by reduced food consumption was detected in males at 500 mg/kg bw/day and females at 150 mg/kg bw/day and higher. Body weight gains on Days 1-7, Days 21 -28 and Days 35-43 of administration in males at 500 mg/kg bw/day, on Days 1-7 of administration, Days 7-14 and Days 14-21 of pregnancy and Days 0-4 of lactation in females at 500 mg/kg bw/day, and Days 1-7 of administration, Days 0-7 of pregnancy and Days 0-4 of lactation in females at 150 mg/kg bw/day were found. Absolute and relative weights of the testes and epididymides in the groups treated with this chemical were not different from the control group. Necropsy and histopathological examinations revealed no changes related to the administration of this chemical. Histopathological examinations of the testes, epididymides and ovaries revealed no toxicological changes. There were no adverse effects on estrous cyclicity, copulation index, fertility index, precoital interval, gestation length, gestation index or number of corpora lutea. No significant changes were observed in numbers of implantations and pups and live pups, and in indexes for implantation, delivery, birth and live birth. There were no treatment- related changes in body weight, external appearance or necropsy findings in offspring of rats.

Based on the absence of any adverse effects on reproductive and developmental parameter, the NOAEL for reproductive and developmental toxicity is considered to be 500 mg/kg bw/day. Further, based on clinical signs and decreased body weight gain and food consumption, the LOAEL and NOAEL for general toxicity in parent animals are considered to be 150 and 50 mg/kg bw/day, respectively.