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Toxicological information

Toxicity to reproduction

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Administrative data

Endpoint:
multi-generation reproductive toxicity
Remarks:
four generation study with embedded continuous breeding study
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
Justification for type of information:
This endpoint study record is the experimental source record for the registered target substance.
Cross-referenceopen allclose all
Reason / purpose:
reference to same study
Reference
Endpoint:
in vivo mammalian somatic cell study: gene mutation
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
Justification for type of information:
This endpoint study record is the experimental source record for the registered target substance.
Reason / purpose:
reference to same study
Related information:
Composition 1
Reason / purpose:
reference to same study
Related information:
Composition 1
Reason / purpose:
reference to same study
Related information:
Composition 1
Reference:
Composition 0
Principles of method if other than guideline:
genotoxicity test in vivo after subchronic oral exposure
GLP compliance:
not specified
Type of assay:
rodent dominant lethal assay
Test material information:
Composition 1
Specific details on test material used for the study:
The test compound, 1,3-butanediol, was obtained from the Celanese Chemical Company, New York
Species:
rat
Strain:
Wistar
Details on species / strain selection:
Wistar rats (FDRL-stock)
Sex:
male/female
Details on test animals and environmental conditions:
TEST ANIMALS
- Age at study initiation: 14-15 weeks
- Housing: individually
- Diet: ad libitum
- Water: ad libitum

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 22 +/- 2 °C
- Photoperiod: 12 h dark / 12 h light
Route of administration:
oral: feed
Details on exposure:
SEMIPURIFIED DIET
20% casein
8% refined corn oil
4% salt mix
1% vitamin mix
33.5% corn starch
33.5% dextrose

DIET PREPARATION
- test diets were prepared by substituting 1,3-butanediol for equal amounts by weight of corn starch and dextrose
Duration of treatment / exposure:
Rats were treated 4 weeks before the mating period. Female rats of the F0 were fed diets containing 1,3-butanediol throughout the mating, gestation and lactating period of the F1A generation. At 1-2 weeks after weaning of the F1A litter, F0 females were mated with different males and the F1B generation was produced. Ten males per dose group of F1B generation were used for the dominant lethal test. They were housed individually in mating cages and fed the same diet concentrations as the F0 generation. For 8 consecutive weeks, 2 virgin females (100 days old) were introduced each and remained for 7 days. Afterwards the females were kept individually for another 7 days and then examined.
Frequency of treatment:
daily
Post exposure period:
none
Dose / conc.:
0 other: % Basis: nominal in diet
Dose / conc.:
5 other: % Basis: nominal in diet
Dose / conc.:
10 other: % Basis: nominal in diet
Dose / conc.:
24 other: % Basis: nominal in diet
No. of animals per sex per dose:
ten males of the F1B generation
Control animals:
yes, concurrent no treatment
Positive control(s):
None
Tissues and cell types examined:
The reproductive tract of the mated females was examined with respect to the number of implantates, resorption sites, viable and dead fetuses
Evaluation criteria:
The mutagenic index (% resorptions/implantation sites) was calculated according to a method of Epstein and Schaffer.
Statistics:
Statistical analysis was performed, but not stated in detail
Sex:
male/female
Genotoxicity:
negative
Toxicity:
no effects
Remarks:
only slight depression of body weight gain
Vehicle controls valid:
not applicable
Negative controls valid:
yes
Positive controls valid:
not applicable
Additional information on results:
Dietary concentrations of 5, 10 and 24% correspond with body doses of 2000, 4000 and 9600 mg/kg bw for males and 2500, 5000 and 12000 mg/kg bw for females (based on a daily food consumption of 40 and 50 g/kg bw for males and females, respectively, according to the Guidance on Information Requirements R.8).

The percentage of pregnancies as well as the percentage of viable fetuses per implantation site were not significantly different between treatment and control groups. The mutagenic index did not show a trend with increasing doses

 

Control

5%

10%

24%

No. pregnancies total

106

97

130

117

% Pregnancies (20 matings)

66.3

60.6

81.3

73.1

Implant sites

1165

1024

1452

1310

Viable fetuses total

1101

962

1389

1269

% Viable fetuses/implant sites

94.5

94.0

95.7

96.9

Resorptions total

64

62

63

41

% Resorptions/implant sites*

5.5

6.1

4.3

3.1

*: mutagenic index

Conclusions:
The test substance did not induce dominant lethal effects after oral exposure of rats with dietary concentrations of up to 24%.
Executive summary:

Rats were fed butane-1,3-diol in concentrations up to 24% of the diet and paired to produce F1A and F1B litters. Males of the F1B generation were used to examine dominant lethal effects after mating them with virgin females. The exposure did not cause a significant effect with respect to fertility, viable fetuses per implantation sites and percentage of resorption per implantation sites (mutagenic index). A dose-related trend was not evident.

 

This study was performed at high doses, which produced body weight gain. Deficiencies of this study are the incomplete data reporting (e.g. with respect to substance purity, statistical analysis of the results). In summary, this study is judged to be reliable with restrictions.

Reason / purpose:
reference to same study
Reference
Endpoint:
in vivo mammalian somatic cell study: cytogenicity / bone marrow chromosome aberration
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
Justification for type of information:
This endpoint study record is the experimental source record for the registered target substance.
Reason / purpose:
reference to same study
Related information:
Composition 1
Reason / purpose:
reference to same study
Related information:
Composition 1
Reason / purpose:
reference to same study
Related information:
Composition 1
Reference:
Composition 0
Principles of method if other than guideline:
genotoxicity test in vivo after subchronic oral exposure over 3 generations
GLP compliance:
not specified
Type of assay:
other: chromosome aberration assay
Test material information:
Composition 1
Specific details on test material used for the study:
The test compound, 1,3-butanediol, was obtained from the Celanese Chemical Company, New York
Species:
rat
Strain:
Wistar
Details on species / strain selection:
Wistar rats (FDRL-stock)
Sex:
male/female
Details on test animals and environmental conditions:
TEST ANIMALS
- Age at study initiation: 14-15 weeks
- Housing: individually
- Diet: ad libitum
- Water: ad libitum

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 22 +/- 2 °C
- Photoperiod: 12 h dark / 12 h light
Route of administration:
oral: feed
Details on exposure:
SEMIPURIFIED DIET
20% casein
8% refined corn oil
4% salt mix
1% vitamin mix
33.5% corn starch
33.5% dextrose

DIET PREPARATION
- test diets were prepared by substituting 1,3-butanediol for equal amounts by weight of corn starch and dextrose
Duration of treatment / exposure:
Rats were treated 4 weeks before the mating period. Female rats of the F0 were fed diets containing 1,3-butanediol throughout the mating, gestation and lactating period of the F1A generation. Pubs of the F1A were reared to maturity. After 11 weeks of feeding, 25 males and 25 females from each dosage group of F1A animals were randomly selected and paired to produce the F2A generation and the F2A litter was mated to produce the F3A generation.
Frequency of treatment:
daily
Post exposure period:
none
Dose / conc.:
0 other: % Basis: nominal in diet
Dose / conc.:
5 other: % Basis: nominal in diet
Dose / conc.:
10 other: % Basis: nominal in diet
Dose / conc.:
24 other: % Basis: nominal in diet
No. of animals per sex per dose:
F0: 25 males, 25 females
At least two animals per sex per dose from the F1A, F2A and F3A generation were examined.
Control animals:
yes, concurrent no treatment
Positive control(s):
None
Tissues and cell types examined:
femur bone marrow
Details of tissue and slide preparation:
DETAILS OF SLIDE PREPARATION:
Animals were treated with 1 mg/kg bw colchicine intraperitoneally 3-4 h prior to examination (exact time point of examination not stated). The bone marrow was washed with 5 ml of Hank's balanced salt solution (HBSS). The isolated cells were washed with HBSS repeatedly, suspended in hypotonic fetal calf serum and incubated for 20 min at 37 °C. Fixation of the cells was performed in methanol/glacial acetic acid (3:1 mixture) overnight at 4 °C and stained on coverslips with 2% aceto-orcein.

METHOD OF ANALYSIS:
100-250 metaphase cells per dose group were examined for chromosomal aberrations at 900x magnification by phase-contrast microscopy.
Statistics:
Statistical analysis was not stated
Sex:
male/female
Genotoxicity:
negative
Toxicity:
no effects
Remarks:
only slight depression of body weight gain
Vehicle controls valid:
not applicable
Negative controls valid:
yes
Positive controls valid:
not applicable
Additional information on results:
Dietary concentrations of 5, 10 and 24% correspond with body doses of 2000, 4000 and 9600 mg/kg bw for males and 2500, 5000 and 12000 mg/kg bw for females (based on a daily food consumption of 40 and 50 g/kg bw for males and females, respectively, according to the Guidance on Information Requirements R.8).

The number of abnormal cells was not increased with respect to the normal range of aberrant cells in untreated F1A, F2A and F3A animals. No specific abnormalities were observed in the treated animals and no dose-related effects were noted.

Conclusions:
The test substance did not induce chromosomal aberrations after subchronic oral exposure of rats over 3 generations with dietary concentrations of up to 24%.
Executive summary:

Rats were fed butane-1,3-diol in concentrations up to 24% of the diet and paired to produce F1A, F2A and F3A litters. Analysis of the femur bone marrow of at least two animals per sex and dose of these litters revealed no increase in chromosomal aberrations.

This study was well performed with doses high enough to cause a reduced body weight gain. Despite some conceptional deficiencies (no positive controls, low numbers of cells per dose group examined) as well as incomplete data reporting (e.g. with respect to substance purity, time point of examination, statistical analysis of the results) this study is judged to be reliable and sensitive, due to the repeated application of high doses over long time periods and several generations.

Reason / purpose:
reference to same study
Reference
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
Justification for type of information:
This endpoint study record is the experimental source record for the registered target substance.
Reason / purpose:
reference to same study
Related information:
Composition 1
Reason / purpose:
reference to same study
Related information:
Composition 1
Reason / purpose:
reference to same study
Related information:
Composition 1
Reference:
Composition 0
Principles of method if other than guideline:
study on teratogenicity
GLP compliance:
not specified
Limit test:
no
Test material information:
Composition 1
Specific details on test material used for the study:
The test compound, 1,3-butanediol, was obtained from the Celanese Chemical Company, New York
Species:
rat
Strain:
Wistar
Details on test animals and environmental conditions:
TEST ANIMALS
- Age at study initiation: 14-15 weeks
- Housing: individually
- Diet: ad libitum
- Water: ad libitum
ENVIRONMENTAL CONDITIONS
- Temperature (°C): 22 +/- 2 °C
- Photoperiod: 12 hrs dark/12 hrs light
Route of administration:
oral: feed
Vehicle:
unchanged (no vehicle)
Details on exposure:
SEMIPURIFIED DIET
Casein: 20 %
Refined corn oil: 8%
Salt mix: 4%
Vitamin mix: 1%
Corn starch 33.5%
Dextrose: 33.5%
DIET PREPARATION
- test diets were prepared by substituting 1,3-butanediol for equal amounts by weight of corn starch
and dextrose
Analytical verification of doses or concentrations:
no
Details on mating procedure:
Investigation of teratogenicity was performed with part of the second litter of the F3 generation of a multi generation study
Duration of treatment / exposure:
day 0 to day 19 of gestation, additional to exposure of the parental (F2) and former generations (F0 and F1)
Frequency of treatment:
daily
Dose / conc.:
0 other: % Basis: nominal in diet
Dose / conc.:
5 other: % Basis: nominal in diet
Dose / conc.:
10 other: % Basis: nominal in diet
Dose / conc.:
24 other: % Basis: nominal in diet
No. of animals per sex per dose:
14-15 females per dose group
Control animals:
yes, concurrent no treatment
Maternal examinations:
- sacrifice at day 19 of gestation
- number of implantations, resorptions, viable and nonviable fetuses
Fetal examinations:
- data on growth abnormalities, weight and sex of fetuses were recorded
- one third of fetuses were examined for soft tissue abnormalities and remaining fetuses were used for skeletal examinations
- soft tissue examinations: fetuses of each group were fixed in Bouin's solution, sectioned according to the method of Wilson and examined in detail for abnormalities
- skeletal examinations: fetuses were fixed in ethyl alcohol and stained with alizarin red and examined for defects
Statistics:
Skeletal tissue examinations: evaluated by the approximate chi-square test
Clinical signs:
not specified
Mortality:
not specified
Body weight and weight changes:
no effects observed
Food consumption and compound intake (if feeding study):
no effects observed
Food efficiency:
no effects observed
Ophthalmological findings:
not examined
Haematological findings:
no effects observed
Clinical biochemistry findings:
no effects observed
Urinalysis findings:
no effects observed
Behaviour (functional findings):
not examined
Immunological findings:
not examined
Organ weight findings including organ / body weight ratios:
not specified
Gross pathological findings:
not specified
Neuropathological findings:
not examined
Histopathological findings: non-neoplastic:
not specified
Histopathological findings: neoplastic:
not specified
Number of abortions:
not specified
Pre- and post-implantation loss:
no effects observed
Total litter losses by resorption:
no effects observed
Early or late resorptions:
no effects observed
Dead fetuses:
not specified
Changes in pregnancy duration:
not specified
Description (incidence and severity):
Migrated Data from removed field(s)
Field "Effects on pregnancy duration" (Path: ENDPOINT_STUDY_RECORD.DevelopmentalToxicityTeratogenicity.ResultsAndDiscussion.ResultsMaternalAnimals.MaternalDevelopmentalToxicity.EffectsOnPregnancyDuration): not specified
Changes in number of pregnant:
no effects observed
Dose descriptor:
NOAEL
Effect level:
12 000 mg/kg bw/day (nominal)
Based on:
test mat.
Basis for effect level:
other: No treatment related effects
Remarks on result:
other: calculated (24% in diet, food factor 0.05 according to Guidance on Information Requirements R.8)
Fetal body weight changes:
no effects observed
Description (incidence and severity):
Migrated Data from removed field(s)
Field "Fetal/pup body weight changes" (Path: ENDPOINT_STUDY_RECORD.DevelopmentalToxicityTeratogenicity.ResultsAndDiscussion.ResultsFetuses.FetalPupBodyWeightChanges): not specified
Reduction in number of live offspring:
no effects observed
Changes in sex ratio:
not specified
Changes in litter size and weights:
no effects observed
Changes in postnatal survival:
not specified
External malformations:
not specified
Skeletal malformations:
effects observed, non-treatment-related
Description (incidence and severity):
no definitive dose-related teratological findings in either soft or skeletal tissue
Dose descriptor:
NOAEL
Effect level:
12 000 mg/kg bw/day (nominal)
Based on:
test mat.
Sex:
male/female
Basis for effect level:
other: teratogenicity
Remarks on result:
other: calculated (24% in diet, food factor 0.05 according to Guidance on Informati on Requirements R.8)
Dose descriptor:
LOAEL
Effect level:
5 000 mg/kg bw/day (nominal)
Based on:
test mat.
Sex:
male/female
Basis for effect level:
other: fetotoxicity
Remarks on result:
other: calculated (10% in diet, food factor 0.05 according to Guidance on Informati on Requirements R.8)
Dose descriptor:
NOAEL
Effect level:
2 500 mg/kg bw/day (nominal)
Based on:
test mat.
Sex:
male/female
Basis for effect level:
other: fetotoxicity
Remarks on result:
other: calculated (5% in diet, food factor 0.05 according to Guidance on Information Requirements R.8)
Abnormalities:
not specified
Developmental effects observed:
not specified

Conducted as part of reproduction study;

no definitive dose-related teratological findings in either soft or skeletal tissue.

Fetotoxicity (e.g., delayed ossification of sternebrae) noted at 10% and 24% doses, 5000 and 12000 mg/kg bw/d, respectively.

Incidence of fetal skeletal abnormalities in F3B generation:

 

Dietary level (%)

 

0

5

10

24

No. of fetuses examined

124

103

120

103

Sternebrae

 

Incomplete ossification

31

31

48*

65*

Scrambled

1

0

0

0

Bipartite

1

1

0

3

Extra

1

0

0

0

Missing

10

3

13

37**

Ribs

 

More than 13

4

4

1

1

Vertebrae

 

Incomplete ossification

4

1

1

2

Scoliosis

1

0

0

0

Skull

 

Incomplete closure

9

0

3

10

Hyoid bone

 

Missing

2

0

0

2

Reduced

0

0

0

1

*: significantly different from respective control, p </= 0.025

**: significantly different from respective control, p </= 0.01

Resorption and implantation data for F3B generation:

 

 

Mean no. of pups per litter

 

 

 

Dietary level (%)

No. of pregnant females

Viable

Non-viable

Implantations (mean per dam)

Resorptions (mean per dam)

Mean fetal weight (g)

0

15

11.9

0

12.5

0.6

3.5

5

15

10.1

0

10.4

0.3

4.0

10

14

12.1

0

12.6

0.5

4.1

24

14

10.9

0

11.4

0.5

3.4

 

Conclusions:
No teratogenic effects were seen in rats treated with up to 24% (12000 mg/kg bw/d) (R/S)1,3-butylene glycol in the diet. But fetotoxic effects occurred in concentrations at or above 10% (5000 mg/kg bw/d) (R/S)-1,3-butylene glycol in the diet.
Executive summary:

Teratogenic effects of (R/S)-1,3-butylene glycol were investigated as part of a multi-generation study in rats receiving 0, 5, 10 and 24% (R/S)-1,3-butylene glycol in the diet (0, 2500, 5000, 12000 mg/kg bw/d). No conclusive teratogenic effects were seen in pups of the F3B generation at levels up to 12000 mg/kg bw/d (R/S)-1,3-butylene glycol in the diet. Incomplete sternebral ossification at mid- and high-dose levels and missing sternebrae at high-dose level were noted, probably indicating slight delayed development of fetal skeletal tissue (likely secondary to parental toxicity and stress). The NOAEL for fetotoxicity was 2500 mg/kg bw/d of (R/S)-1,3-butylene glycol in the diet.

The study was judged to be reliable with some minor restrictions due to some shortcomings of the study (e.g. not according to guideline, missing data on test substance purity, no data on sex distribution of the offspring reported although this endpoint was recorded according to the method section).

Data source

Reference
Reference Type:
publication
Title:
Reproduction and teratology study of 1,3-butanediol in rats
Author:
Hess, FG, et al.
Year:
1981
Bibliographic source:
Hess, Frederick G., et al. "Reproduction and teratology study of 1, 3‐butanediol in rats." Journal of Applied Toxicology 1.4 (1981): 202-209.

Materials and methods

Test guideline
Qualifier:
equivalent or similar to
Guideline:
other: Four generation study with embedded continuous breeding study
Version / remarks:
extended EPA OTS 798.4700 (Reproduction and Fertility Effects) study design
Deviations:
not applicable
Principles of method if other than guideline:
Four generation study with embedded continuous breeding study
GLP compliance:
not specified
Limit test:
no

Test material

Reference
Name:
Unnamed
Type:
Constituent
Test material form:
liquid
Details on test material:
no impurities described
Specific details on test material used for the study:
The test compound, 1,3-butanediol, was obtained from the Celanese Chemical Company, New York

Test animals

Species:
rat
Strain:
Wistar
Details on species / strain selection:
Wistar rats (FDRL-stock)
Sex:
male/female
Details on test animals and environmental conditions:
TEST ANIMALS
- Age at study initiation: 14-15 weeks
- Housing: individually
- Diet: ad libitum
- Water: ad libitum

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 22 +/- 2 °C
- Photoperiod: 12 hrs dark/12 hrs light

Administration / exposure

Route of administration:
oral: feed
Vehicle:
unchanged (no vehicle)
Details on exposure:
SEMIPURIFIED DIET
Casein: 20 %
Refined corn oil: 8%
Salt mix: 4%
Vitamin mix: 1%
Corn starch 33.5%
Dextrose: 33.5%

DIET PREPARATION
- test diets were prepared by substituting 1,3-butanediol for equal amounts by weight of corn starch and dextrose
Details on mating procedure:
- M/F ratio per cage: one male/ one female
- Length of cohabitation: 7 days
- Proof of pregnancy: vaginal plug referred to as day 0 of pregnancy
- After 7 days of unsuccessful pairing replacement of first male by another male.
- Further matings after two unsuccessful attempts: no
- After successful mating each pregnant female was caged individually.
Analytical verification of doses or concentrations:
no
Duration of treatment / exposure:
F0 rats were treated 4 weeks before the mating period. Female rats of the F0 were fed diets containing 1,3-butanediol throughout the mating, gestation and lactating period. After 11 weeks of feeding, 25 males and 25 females from each dosage group of F1A animals were randomly selected and paired to produce the F2 generation (no further information).
Frequency of treatment:
daily
Details on study schedule:
At 1-2 weeks after weaning of the first litters (F1A), each female of the F0 generation was mated with a different male and a second series of litters was produced (F1B). All animals of the F1B generation were discarded at weaning except for ten males per group, which were reared to sexual maturity and used in a dominant lethal test. Pubs of the F1A were reared to maturity. After 11 weeks of feeding, 25 males and 25 females from each dosage group of F1A animals were randomly selected and paired to produce the F2 generation. Five successive mating cycles were achieved with the F1A rats within a period of 77 weeks (F2A, F2B, F2C, F2D, F2E). The F2B, F2C, F2D and F2E were examined and sacrificed as part of the continuous breeding phase of the study, while the F2A litter was mated to produce the F3A and F3B litters. The F3A litter was used for the cytogenetic portion of the study and was mated to produce the F4A and F4B litter, which form part of the cytogenicity study. The pregnant dams of the F2A litters (producing the F3B) were divided in two groups: 1/4 were allowed to give birth normally and 3/4 were used for teratological examination on day 19 of gestation.
Doses / concentrationsopen allclose all
Dose / conc.:
0 other: % Basis: nominal in diet
Dose / conc.:
5 other: % Basis: nominal in diet
Dose / conc.:
10 other: % Basis: nominal in diet
Dose / conc.:
24 other: % Basis: nominal in diet
No. of animals per sex per dose:
25 rats per sex per dose group in the F0, F1A, F1B, F2A, F3A
Control animals:
yes, concurrent no treatment

Examinations

Parental animals: Observations and examinations:
After 4 weeks of feeding of the F0 the respective diets, blood samples were collected from ten rats per sex per group for determination of alkaline phosphatase, glucose, hematocrit, hemoglobin and total and differential leucocyte counts. Urine analysis of the same animals provided measurements of albumin, glucose, ketones, occult blood, pH, specific gravity and microscopic examination. For F1A rats which survived at least 66 weeks, the gonads and pituitary glands were examined microscopically. During the eleventh week of feeding of F1A animals blood and urine samples were collected from ten rats per sex per group and evaluated as mentioned above.

Body weight: yes

Reproductive performance: yes
Litter observations:
viability, mean pub weight at day 4 and 21 post partum
Postmortem examinations (parental animals):
histopathologic examination of the testes or ovaries and pituitary glands of the F1A
Reproductive indices:
fertility (percent matings resulting in pregnancies) and gestation indices (percent pregnancies resulting in litters cast alive)
Offspring viability indices:
- percent pubs cast alive that survived to 4 days
- percent pups alive at 4 days that survived to 21 days

Results and discussion

Results: P0 (first parental animals)

General toxicity (P0)

Clinical signs:
not specified
Mortality:
not specified
Body weight and weight changes:
no effects observed
Food consumption and compound intake (if feeding study):
no effects observed
Food efficiency:
no effects observed
Ophthalmological findings:
not examined
Haematological findings:
no effects observed
Clinical biochemistry findings:
no effects observed
Urinalysis findings:
no effects observed
Behaviour (functional findings):
not examined
Immunological findings:
not examined
Organ weight findings including organ / body weight ratios:
not specified
Gross pathological findings:
not specified
Neuropathological findings:
not examined
Histopathological findings: non-neoplastic:
not specified
Histopathological findings: neoplastic:
not specified

Reproductive function / performance (P0)

Reproductive function: estrous cycle:
not specified
Reproductive function: sperm measures:
not specified
Reproductive performance:
no effects observed

Details on results (P0)

BODY WEIGHT AND FOOD CONSUMPTION (PARENTAL ANIMALS)
Female animals showed no significant abnormal growth rates. Body weight gains of male rats in all four generations were slightly depressed with an apparent dose relationship. The efficiency of food utilization through 10 weeks of post-weaning remained constant for all generations of both sexes and was not affected by (R/S)-1,3-butanediol treatment.

No significant treatment-related differences were noted on histopathologic examination of testes or ovaries and pituitary glands.

Effect levels (P0)

Dose descriptor:
NOAEL
Effect level:
12 000 mg/kg bw/day (nominal)
Based on:
test mat.
Sex:
male/female
Basis for effect level:
other: No treatment related effects in F0 generation
Remarks on result:
other:
Remarks:
24% in diet, food factor 0.05 according to Guidance on Information Requirements R.8

Results: F1 generation

General toxicity (F1)

Clinical signs:
not specified
Mortality / viability:
no mortality observed
Body weight and weight changes:
effects observed, treatment-related
Description (incidence and severity):
reduced weight gain F1A, F1B generations
Food consumption and compound intake (if feeding study):
no effects observed
Food efficiency:
no effects observed
Ophthalmological findings:
not examined
Haematological findings:
no effects observed
Clinical biochemistry findings:
no effects observed
Urinalysis findings:
no effects observed
Sexual maturation:
not specified
Organ weight findings including organ / body weight ratios:
not specified
Gross pathological findings:
not specified
Histopathological findings:
not specified

Developmental neurotoxicity (F1)

Behaviour (functional findings):
not examined

Developmental immunotoxicity (F1)

Developmental immunotoxicity:
not examined

Details on results (F1)

BODY WEIGHT AND FOOD CONSUMPTION (PARENTAL ANIMALS)
Female animals showed no significant abnormal growth rates. Body weight gains of male rats in all four generations were slightly depressed with an apparent dose relationship. The efficiency of food utilization through 10 weeks of post-weaning remained constant for all generations of both sexes and was not affected by (R/S)-1,3-butanediol treatment.

REPRODUCTIVE PERFORMANCE (PARENTAL ANIMALS)
During five successive mating cycles of F1A rats, a gradual decrease in the pregnancy rate was seen. Both the number of pregnant females and the fertility index appeared to be dose-related for several series of F2 litters, especially F2D and F2E. For the fifth series of litters, no pups were obtained in the highest-dose group. However, the gestation, viability and lactation indexes, as well as the mean pup body weights at 4 and 21 days showed no significant differences between specific litter series or between control and test groups (excluding high-dose animals of the fifth series of litters).

No significant treatment-related differences were noted on histopathologic examination of testes or ovaries and pituitary glands as a possible explanation of the observed reproductive failure during the fifth cycle.

Effect levels (F1)

open allclose all
Dose descriptor:
LOAEL
Generation:
other: F1A, F1B
Effect level:
12 000 mg/kg bw/day (nominal)
Based on:
test mat.
Sex:
male
Basis for effect level:
body weight and weight gain
Remarks on result:
other:
Remarks:
all generations (F1A, F1B, F2A, F3A) except F0
Dose descriptor:
NOAEL
Generation:
other: F1A, F1B
Effect level:
12 000 mg/kg bw/day (nominal)
Based on:
test mat.
Sex:
female
Basis for effect level:
other: no treatment related effects
Remarks on result:
other:
Remarks:
calculated (24% in diet, food factor 0.05 according to Guidance on Information Requirements R.8)
Dose descriptor:
NOAEL
Generation:
other: F1A, F1B
Effect level:
5 000 mg/kg bw/day (nominal)
Based on:
test mat.
Sex:
male
Basis for effect level:
body weight and weight gain
Remarks on result:
other:
Remarks:
calculated (10% in diet, food factor 0.05 according to Guidance on Information Requirements R.8)

Results: F2 generation

General toxicity (F2)

Clinical signs:
not specified
Mortality / viability:
no mortality observed
Body weight and weight changes:
effects observed, treatment-related
Description (incidence and severity):
reduced weight gain F2A, F3A generations
Food consumption and compound intake (if feeding study):
no effects observed
Food efficiency:
no effects observed
Ophthalmological findings:
not examined
Haematological findings:
no effects observed
Clinical biochemistry findings:
no effects observed
Urinalysis findings:
no effects observed
Sexual maturation:
not specified
Organ weight findings including organ / body weight ratios:
not specified
Gross pathological findings:
not specified
Histopathological findings:
not specified

Developmental neurotoxicity (F2)

Behaviour (functional findings):
not examined

Developmental immunotoxicity (F2)

Developmental immunotoxicity:
not examined

Details on results (F2)

BODY WEIGHT AND FOOD CONSUMPTION (PARENTAL ANIMALS)
Female animals showed no significant abnormal growth rates. Body weight gains of male rats in all four generations were slightly depressed with an apparent dose relationship. The efficiency of food utilization through 10 weeks of post-weaning remained constant for all generations of both sexes and was not affected by (R/S)-1,3-butanediol treatment.

REPRODUCTIVE PERFORMANCE (PARENTAL ANIMALS)
During five successive mating cycles of F1A rats, a gradual decrease in the pregnancy rate was seen. Both the number of pregnant females and the fertility index appeared to be dose-related for several series of F2 litters, especially F2D and F2E. For the fifth series of litters, no pups were obtained in the highest-dose group. However, the gestation, viability and lactation indexes, as well as the mean pup body weights at 4 and 21 days showed no significant differences between specific litter series or between control and test groups (excluding high-dose animals of the fifth series of litters).

No significant treatment-related differences were noted on histopathologic examination of testes or ovaries and pituitary glands as a possible explanation of the observed reproductive failure during the fifth cycle.

For the other three generations of dams and pups, no significant dose-related trends were observed for the reproduction and lactation parameters, as described above.

Effect levels (F2)

open allclose all
Dose descriptor:
LOAEL
Generation:
other: F2A, F3A
Effect level:
12 000 mg/kg bw/day (nominal)
Based on:
test mat.
Sex:
male
Basis for effect level:
body weight and weight gain
Remarks on result:
other:
Remarks:
calculated (24% in diet, food factor 0.05 according to Guidance on Information Requirements R.8)
Dose descriptor:
LOAEL
Generation:
other: F2E
Effect level:
12 000 mg/kg bw/day (nominal)
Based on:
test mat.
Sex:
female
Basis for effect level:
other: no pregnant females to produce the F2E generation; reduced number of females in former litters of the F2 generation
Remarks on result:
other:
Remarks:
calculated (24% in diet, food factor 0.05 according to Guidance on Information Requirements R.8)
Dose descriptor:
NOAEL
Generation:
other: FE2
Effect level:
5 000 mg/kg bw/day (nominal)
Based on:
test mat.
Sex:
female
Basis for effect level:
other: no pregnant females to produce the F2E generation; reduced number of females in former litters of the F2 generation
Remarks on result:
other:
Remarks:
calculated (10% in diet, food factor 0.05 according to Guidance on Information Requirements R.8)
Dose descriptor:
NOAEL
Generation:
other: F2A, F3A
Effect level:
5 000 mg/kg bw/day (nominal)
Based on:
test mat.
Sex:
male
Basis for effect level:
body weight and weight gain
Remarks on result:
other:
Remarks:
(10% in diet, food factor 0.05 according to Guidance on Information Requirements R.8)

Overall reproductive toxicity

Reproductive effects observed:
not specified

Any other information on results incl. tables

Body weight gain of male rats is presented in the following table:

Generation

Dietary level (%)

Weeks

Mean weight gain (g)

F0

0

23

153

 

5

23

149

 

10

23

141

 

24

23

149

F1A

0

77

481

 

5

77

429

 

10

77

410

 

24

77

383

F1B

0

11

298

 

5

11

278

 

10

11

263

 

24

11

257

F2A

0

11

305

 

5

11

282

 

10

11

278

 

24

11

272

F3A

0

9

296

 

5

9

270

 

10

9

263

 

24

9

222

 

Applicant's summary and conclusion

Conclusions:
1,3-butylene glycol did not influence fertility in a four generation study with an embedded continuous breeding study in concentrations up to 10% in the diet (5000 mg/kg bw/d). In the highest concentration tested (24%, 12000 mg/kg bw/d) no offspring in the fifth litter of the F2 generation were produced (likely secondary to parental toxicity and stress).
Executive summary:

Twenty five animals of both sexes were fed either control diet or diet supplemented with 1,3-butylene glycol at dose levels of 5, 10 or 24% of the diet (2500, 5000 or 12000 mg/kg bw/d). Treatment with the test item had no influence on reproduction and lactation parameters for all but one group of dams and pups. The pregnancy rate of F1A rats decreased during five successive mating cycles (likely secondary to parental toxicity and stress): no pups were obtained at the high-dose level group of the fifth series of litters (F2E generation). However, the added stress of a highly ketogenic, semi-synthetic diet may have contributed significantly to this effect. A significant increase in the concentration of ketone bodies in blood, urine and liver tissues was noted in rats fed diets contain 1,3-butanediol at the levels of 20 or 25% (study referenced in journal article). Therefore, physiological stress may be associated with increased ingestion of 1,3-butanediol.

Excluding F2E group, the viability of F2 generation pups revealed no significant differences between litters or between control and test groups. Body weight gains of male rats in all four generations were slightly depressed with an apparent dose relationship. Body weight gain of females was not affected.

 

Documentation of this well-planned study is insufficient: Exposure duration is not clearly stated, purity of the test item is not given. Examination of the parental generation is insufficient (e.g.no histopathological examination of sexual organs), test results were not evaluated statistically. Despite these shortcomings the study was judged to be reliable with restrictions as it indicates that fertility is not impaired through 1,3-butylene glycol exposure up to 10% in diet (5000 mg/kg bw/d).