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Toxicological information

Toxicity to reproduction

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Administrative data

Endpoint:
multi-generation reproductive toxicity
Remarks:
five generation study with embedded continuous breeding study
Type of information:
experimental study
Adequacy of study:
key study
Study period:
1981
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: publication with some shortcomings in documentation (purity of test substance not stated, exposure duration not clearly stated, no statistical evaluation)

Data source

Reference
Reference Type:
publication
Title:
Unnamed
Year:
1981
Report Date:
1981

Materials and methods

Test guideline
Qualifier:
no guideline followed
Principles of method if other than guideline:
five 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:
- Name of test material (as cited in study report): 1,3-butanediol
Test material obtained from Celanese Chemical Company, New York

Test animals

Species:
rat
Strain:
Wistar
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
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 are indicated by the chart in the orginal paper to be 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 / concentrations
Remarks:
0, 5, 10 and 24 % nominal in diet, corresponding to 0, 2500, 5000 and 12000 mg/kg bw/day, calculated with food factor 0.05 according to Guidance on Information Requirements R.8
No. of animals per sex per dose:
25 rats per sex per dose group in the F0, F1A, F1B, F2A, F3A
Control animals:
yes, plain diet
Positive control:
none

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

Reproductive function / performance (P0)

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

Details on results (P0)

BODY WEIGHT AND FOOD CONSUMPTION (PARENTAL ANIMALS)
Female animals showed no significant abnormal growth rates. Except the P0-Generation, body weight gains of male rats in all four consecutive generations were slightly depressed with an apparent dose relationship (for details see below). The efficiency of food utilization through 10 weeks of post-wening remained constant for all generations of both sexes and was not affected by 1,3-BD treatment.

CLINICAL STUDIES
Hematology, blood chemistry and urinalysis showed no trend associated with treatment for F0, F1, F2 and F3 generation animals

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 (P0)

open allclose all
Key result
Dose descriptor:
NOAEL
Effect level:
12 000 mg/kg bw/day
Based on:
test mat.
Sex:
male/female
Basis for effect level:
other: absence of adverse effects
Remarks on result:
other: dose calculated (24% in diet, food factor 0.05 according to Guidance on Information Requirements R.8)
Key result
Dose descriptor:
NOAEL
Effect level:
12 000 mg/kg bw/day
Based on:
test mat.
Sex:
female
Basis for effect level:
other: absence of effects on reproduction
Remarks on result:
other: dose calculated (24% in diet, food factor 0.05 according to Guidance on Information Requirements R.8)

Target system / organ toxicity (P0)

Key result
Critical effects observed:
no
Lowest effective dose / conc.:
12 000 mg/kg bw/day (nominal)

Results: P1 (second parental generation)

General toxicity (P1)

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

Reproductive function / performance (P1)

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

Details on results (P1)

BODY WEIGHT AND FOOD CONSUMPTION (PARENTAL ANIMALS)
Female animals showed no significant abnormal growth rates. Body weight gains of adult male rats in four F1 generations were slightly depressed with an apparent dose relationship (for details see bel
ow). The efficiency of food utilization through 10 weeks of post-wening remained constant for all generations of both sexes and was not affected by 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 t
he 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 signifi
cant 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 (P1)

open allclose all
Key result
Dose descriptor:
LOAEL
Effect level:
12 000 mg/kg bw/day
Based on:
test mat.
Sex:
male
Basis for effect level:
body weight and weight gain
Remarks on result:
other: dose calculated (24% in diet, food factor 0.05 according to Guidance on Information Requirements R.8)
Key result
Dose descriptor:
LOAEL
Effect level:
12 000 mg/kg bw/day
Based on:
test mat.
Sex:
female
Basis for effect level:
reproductive performance
Remarks on result:
other: dose calculated (24% in diet, food factor 0.05 according to Guidance on Information Requirements R.8)
Key result
Dose descriptor:
NOAEL
Effect level:
5 000 mg/kg bw/day
Based on:
test mat.
Sex:
male
Basis for effect level:
body weight and weight gain
Remarks on result:
other: dose calculated (24% in diet, food factor 0.05 according to Guidance on Information Requirements R.8)
Key result
Dose descriptor:
NOAEL
Effect level:
5 000 mg/kg bw/day
Based on:
test mat.
Sex:
female
Basis for effect level:
reproductive performance
Remarks on result:
other: dose calculated (24% in diet, food factor 0.05 according to Guidance on Information Requirements R.8)

Target system / organ toxicity (P1)

open allclose all
Key result
Critical effects observed:
yes
Lowest effective dose / conc.:
12 000 mg/kg bw/day (nominal)
System:
other: unspecific effects
Organ:
other: body weight gain
Treatment related:
yes
Dose response relationship:
yes
Relevant for humans:
yes
Key result
Critical effects observed:
yes
Lowest effective dose / conc.:
12 000 mg/kg bw/day (nominal)
System:
female reproductive system
Organ:
other: reduced fertility
Treatment related:
yes
Dose response relationship:
yes
Relevant for humans:
yes

Results: F1 generation

General toxicity (F1)

Clinical signs:
no effects observed
Mortality / viability:
no mortality observed
Body weight and weight changes:
no effects observed
Food consumption and compound intake (if feeding study):
not specified
Food efficiency:
no effects observed
Water consumption and compound intake (if drinking water study):
not specified
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 specified

Developmental immunotoxicity (F1)

Developmental immunotoxicity:
not specified

Details on results (F1)

- no treatment related effects in F1 offspring (details for the effects of P1 generation (F2 litters) are presented above and in the attached document)

Effect levels (F1)

Key result
Dose descriptor:
NOAEL
Generation:
F1
Effect level:
12 000 mg/kg bw/day
Based on:
test mat.
Sex:
male/female
Basis for effect level:
other: no developmental toxicity
Remarks on result:
other: maternal dose calculated (24% in diet, food factor 0.05 according to Guidance on Information Requirements R.8)

Target system / organ toxicity (F1)

Key result
Critical effects observed:
no
Lowest effective dose / conc.:
12 000 mg/kg bw/day (nominal)
System:
other: no developmental effects observed

Results: F2 generation

General toxicity (F2)

Clinical signs:
no effects observed
Mortality / viability:
no mortality observed
Body weight and weight changes:
no effects observed
Food consumption and compound intake (if feeding study):
not specified
Food efficiency:
no effects observed
Water consumption and compound intake (if drinking water study):
not examined
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

Effect levels (F2)

Key result
Dose descriptor:
NOAEL
Generation:
other: F2A-F2E
Effect level:
12 000 mg/kg bw/day
Based on:
test mat.
Sex:
male/female
Basis for effect level:
other: no developmental effects
Remarks on result:
other: maternal dose calculated (24% in diet, food factor 0.05 according to Guidance on Information Requirements R.8)

Target system / organ toxicity (F2)

Key result
Critical effects observed:
no
Lowest effective dose / conc.:
12 000 mg/kg bw/day (nominal)
System:
other: no developmental effects observed

Overall reproductive toxicity

Key result
Reproductive effects observed:
yes
Lowest effective dose / conc.:
12 000 mg/kg bw/day
Treatment related:
yes
Relation to other toxic effects:
reproductive effects in the absence of other toxic effects
Dose response relationship:
yes
Relevant for humans:
yes

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  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 five 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.
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 four of five generations of dams and pups. The pregnancy rate of F1A rats decreased during five successive mating cycles: no pups were obtained at the high-dose level group of the fifth series of litters (F2E generation). Excluding this 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 (Hess et al., 1981).

The study indicates that fertility is not impaired through 1,3 -butylene glycol exposure up to 10% in diet (5000 mg/kg bw/d).