3-methoxybutyl acetate

Toxicity to reproduction

Administrative data

Endpoint:

multi-generation reproductive toxicity

Remarks:

based on test type (migrated information)

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: GLP status not known, near guideline study, published in peer reviewed literature, minor restrictions in design and/or reporting but otherwise adequate for assessment.

Justification for type of information:

The purpose of this assessment is the presentation of a cohesive rationale for using data from proximate metabolites in the metabolic pathway for 3-methoxybutanol (i.e.3-methoxy acetate (Butoxyl) and 1,3-butanediol) to fill data gaps on sensitization, in vivo genotoxicity, repeated dose toxicity, reproductive and developmenatl toxicity for 3-methoxybutanol as required for REACH registration.

Cross-reference

Reason / purpose for cross-reference:

reference to same study

Data source

Reference

Reference Type:

publication

Title:

Unnamed

Year:

1981

Materials and methods

Test guideline

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 416 (Two-Generation Reproduction Toxicity Study)

Deviations:

yes

Remarks:

Basic design is FDA multigeneration study but over 5 generations, 2 years. 2 matings per generation except for F2 generation where there were 5 matings. The study also incorporated cytogenetics, dominant lethal and teratology phases.

Principles of method if other than guideline:

Several studies were conducted including reproductive, teratogenic, dominant lethal and cytogenic effects in 5 generations of rats over a two year period accoridng to the US FDA operating protocols

GLP compliance:

not specified

Remarks:

experimental program conducted at the USFDA facility

Limit test:

no

Justification for study design:

US FDA Reproduction Program

Test material

Test material information

Constituent 1

Reference substance name:

Butane-1,3-diol

EC Number:

203-529-7

EC Name:

Butane-1,3-diol

Cas Number:

107-88-0

Molecular formula:

C4H10O2

IUPAC Name:

butane-1,3-diol

Details on test material:

- Name of test material (as cited in study report): 1,3-butanediol
- Supplied by: Celanese Chemical Company, New York, USA
- No further details

Specific details on test material used for the study:

Name: 1,3-butanediol
Manufacturer: Celanese Chemical Company
Detalles an test material: purity bot reported

Test animals

Species:

rat

Strain:

other: Wistar (FDRL-stock)

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Age at study initiation: 14-15 weeks
- Housing: Individually except during mating
- Diet: Semi-purified diet ad libitum (20% casein, 8% refined corn oil, 4% salt mix, 1% vitamin mix, 33.5% corn starch, 33.5% dextrose)):
- Water: tap water ad libitum

ENVIRONMENTAL CONDITIONS
- Temperature: 22±2°C
- Photoperiod: 12 hrs dark / 12 hrs light

Administration / exposure

Route of administration:

oral: feed

Vehicle:

other: diet (by replacing equal amounts of corn starch and dextrose with 1,3-butanediol)

Details on exposure:

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: 1:1
- 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 with proven fertility.
- Further matings after two unsuccessful attempts: no

Analytical verification of doses or concentrations:

not specified

Details on analytical verification of doses or concentrations:

not specified

Duration of treatment / exposure:

Approximately 2 years. (F0 generation fed test diets for 4 weeks and then mated to produce F1A litters. One to two weeks after weaning, each F0 female was mated with a different male to produce the F1B litters. Pregnant F0 rats fed test diet throughout mating, gestation and lactation. After 11 weeks of feeding test diets, 25/sex/group from the F1A generation were selected and mated to produce F2 generation and this process was continued to complete 5 successive mating cycles over a period of 77 weeks. Each set of parents was mated twice to produce A and B litters, except for the F1A generation which were mated 5 times to produce F2A, F2B, F2C, F2D and F2E litters).

Frequency of treatment:

Continuous for four consecutive generations

Details on study schedule:

F0 generation:
25/sex/group mated (x2) to produce F1A (used for longevity phase and cytogenetic study) and F1B (10 males/group used for dominant lethal study)

F1A generation:
25/sex/group mated (x5) to produce F2A (used for cytogenetic study), F2B, F2C, F2D and F2E

F2A generation:
25/sex/group mated (x2) to produce F3A (cytogenetic study) and F3B (teratogenicity study. On day 19 of pregnancy ¾ of F2A mothers killed and the F2B foetuses delivered by caesarean and evaluated for teratogenicity)

F3A generation:
25/sex/group mated (x2) to produce F4A and F4B

F0 males and females fed test diet for 4 weeks prior to first mating.
Second (or subsequent) matings to produce the B (C, D and E) litters commenced 1-2 weeks after weaning A litters
The offspring from the A litters were randomly selected and mated after 11 weeks of feeding to produce the next generation.

Doses / concentrations

Doses / concentrations 1

Dose / conc.:

0 other: % of the diet by weight

Remarks:

0 mg/kg/day

Doses / concentrations 2

Dose / conc.:

5 other: % of the diet by weight

Remarks:

2600 mg/kg/day

Doses / concentrations 3

Dose / conc.:

10 other: % of the diet by weight

Remarks:

5200 mg/kg/day

Doses / concentrations 4

Dose / conc.:

24 other: % of the diet by weight

Remarks:

12480 mg/kg/day

No. of animals per sex per dose:

F1A (parents) = 25 rats per sex per dose
F2A, F2B, F2C, F2D, F2E = 25 females rats per sex
F3A = 25 female rats
F4A = 25 female rats
F4B

Control animals:

yes, concurrent vehicle

Details on study design:

according to the US FDA reproduction protocols

Examinations

Parental animals: Observations and examinations:

CAGE SIDE OBSERVATIONS: No data

DETAILED CLINICAL OBSERVATIONS: No data

BODY WEIGHT: Yes
- Time schedule for examinations: No data

FOOD CONSUMPTION AND UTILISATION: Yes
- Time schedule for examinations: No data

WATER CONSUMPTION: No

CLINICAL STUDIES (BLOOD): Yes
- Animals tested: F0 generation after 4 weeks of administration (10/sex/group), F1A after 11 weeks of administration (10/sex/group)
- Parameters measured: alkaline phosphatase, glucose, haematocrit, haemoglobin, total and differential leukocyte counts

URINALYSIS: Yes
- Animals tested: F0 generation after 4 weeks of administration (10/sex/group), F1A after 11 weeks of administration (10/sex/group)
- Parameters measured: albumin, glucose, ketones, occult blood, pH, specific gravity, microscopic examination of sediment

CYTOGENICITY STUDY: Yes
- Animals tested: F1A, F2A and F3A animals (at least 2/sex/group)
- Procedure: rats given ip injection of 1 mg/kg bw colchicine 3-4 hour prior to sacrifice. Bone marrow (femur) preparations examined cytologically for chromosomal aberrations. 100-250 metaphase cells examined per group.

Sperm parameters (parental animals):

not specified but only that histopathology of testes was conducted.

Litter observations:

see below

Postmortem examinations (parental animals):

histopathological eaxminations of specific organs inlcuding testes, ovaries and pituitary glands

Postmortem examinations (offspring):

see below

Statistics:

No specified

Reproductive indices:

see below

Offspring viability indices:

see below

Results and discussion

Results: P0 (first parental generation)

General toxicity (P0)

Clinical signs:

no effects observed

Description (incidence and severity):

no available data on detailed clinical signs

Mortality:

no mortality observed

Body weight and weight changes:

effects observed, non-treatment-related

Description (incidence and severity):

Males body weight gain in all generations were slightly decreased but not statistically significantly different

Food consumption and compound intake (if feeding study):

no effects observed

Food efficiency:

not specified

Water consumption and compound intake (if drinking water study):

not specified

Ophthalmological findings:

not specified

Haematological findings:

no effects observed

Clinical biochemistry findings:

no effects observed

Urinalysis findings:

no effects observed

Behaviour (functional findings):

no effects observed

Immunological findings:

no effects observed

Organ weight findings including organ / body weight ratios:

not examined

Histopathological findings: non-neoplastic:

no effects observed

Histopathological findings: neoplastic:

not specified

Other effects:

not specified

Reproductive function / performance (P0)

Reproductive function: oestrous cycle:

not examined

Reproductive function: sperm measures:

not examined

Reproductive performance:

no effects observed

Details on results (P0)

see below

Effect levels (P0)

Key result

Dose descriptor:

NOAEL

Effect level:

24 other: % of the diet by weight

Based on:

test mat.

Sex:

male/female

Basis for effect level:

reproductive performance

Results: F1 generation

General toxicity (F1)

Clinical signs:

no effects observed

Mortality / viability:

no mortality observed

Body weight and weight changes:

effects observed, non-treatment-related

Description (incidence and severity):

slight decrease in the body weights of all animals due to dietary inbalance

Food consumption and compound intake (if feeding study):

no effects observed

Food efficiency:

effects observed, non-treatment-related

Water consumption and compound intake (if drinking water study):

not specified

Ophthalmological findings:

not specified

Haematological findings:

no effects observed

Clinical biochemistry findings:

no effects observed

Urinalysis findings:

no effects observed

Sexual maturation:

not examined

Organ weight findings including organ / body weight ratios:

not examined

Gross pathological findings:

not examined

Histopathological findings:

no effects observed

Description (incidence and severity):

on the examination of the testes or ovaries and pituitary glands

Developmental neurotoxicity (F1)

Behaviour (functional findings):

not examined

Developmental immunotoxicity (F1)

Developmental immunotoxicity:

not examined

Details on results (F1)

see below

Effect levels (F1)

Key result

Dose descriptor:

NOAEL

Generation:

F1

Effect level:

24 other: % of the diet by weight

Based on:

test mat.

Sex:

male/female

Basis for effect level:

other: inbalance diet and ketones

Remarks on result:

other:

Remarks:

The last two litters produced by the F1A generations (F2D and F2E) showed reduced fertility in the high dose group, which was likely due to growth depression (related to an inbalanced diet and ketone bodies) in the males from the two highest dose groups that were used for mating and treated for up to 66 weeks before they bore the last two litters. There was also no historical control data to evaluate the reproductive performance of approximately one year old rats that had already been mated several times. The gestation, viability and lactation indexes, as well as the mean pup body weights at 4 and 21 days showed no effects in any group

Results: F2 generation

General toxicity (F2)

Clinical signs:

no effects observed

Mortality / viability:

no mortality observed

Body weight and weight changes:

effects observed, non-treatment-related

Description (incidence and severity):

slightly reduced body weights in males due to inbalance diet and ketones

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 specified

Haematological findings:

no effects observed

Clinical biochemistry findings:

no effects observed

Urinalysis findings:

no effects observed

Sexual maturation:

no effects observed

Organ weight findings including organ / body weight ratios:

not specified

Gross pathological findings:

no effects observed

Histopathological findings:

no effects observed

Developmental neurotoxicity (F2)

Behaviour (functional findings):

not specified

Developmental immunotoxicity (F2)

Developmental immunotoxicity:

not specified

Details on results (F2)

Five continuos mating cyles of F1A rats were done to produce F2A-E. Pups were not obtained in the F2E at the high dose. There was not significant difference in gestation rate, viability and lactation indexes, mean pup body weights between pups from the five mating cycles, test groups and control. no significat differences were seen in the testes, ovaries and pituitary glands. No explanation was found and/or reported for the reduce reproductive rate. It is worth to note that animals from F1A were too old at the time for pregnacy for F2E.

Animals from F3A & F3B in the study were asigned to a cytogenicity assay and teratogenicity study, respectively. Animals from F4A and F4B asignation was not specified in the publication.

Effect levels (F2)

Key result

Dose descriptor:

NOEL

Generation:

other: F2A, F2B, F2C, F2E

Effect level:

24 other: % of the diet by weight

Based on:

test mat.

Sex:

male/female

Basis for effect level:

other: no adverse toxic effect on reproduction and lactation. However, an apparent dose-related effect in reduce fertility occurred in F2E,

Remarks on result:

other:

Target system / organ toxicity (F2)

Key result

Critical effects observed:

no

Lowest effective dose / conc.:

24 other: % of the diet by weight

System:

female reproductive system

Organ:

other: fertility in the sucessive mating of F1A rats specifically in F2E.

Overall reproductive toxicity

1

Reproductive effects observed:

not specified

2

Key result

Reproductive effects observed:

yes

Lowest effective dose / conc.:

5 other: % of the diet by weight

Treatment related:

yes

Relation to other toxic effects:

reproductive effects in the absence of other toxic effects

Dose response relationship:

yes

Relevant for humans:

no

Any other information on results incl. tables

For four consecutive generations, bodyweights of males were slightly reduced with an apparent dose relationship. Females were not affected. Food utilisation efficiency was not affected for either sex in any generation.

There were treatment-related effects seen in haematological, blood clinical chemistry or urinalysis parameters.

The pregnancy rate of F1A rats decreased during five successive mating cycles. The number of pregnant females and the fertility index appeared dose-related for the D and E litters. Excluding this group, the viability of F2 generation pups revealed no significant differences between litters or between control and test groups. No reason for the decrease in fertility index in the fifth generation was determined; however, controls were also affected but to a lesser degree.

 

Table 1: Fertility Index (%) in the F2 generation over 5 successive mating cycles

Dose level	Generation
	F2A	F2B	F2C	F2D	F2E
0% (control)	72	44	64	60	40
5%	80	44	76	60	16
10%	92	64	68	40	20
24%	76	52	44	28	0

 

Reproduction, gestation and lactation parameters and day 4 and 21 pup bodyweights were comparable to controls for four of the five generations of dams and pups.

 

There was no definitive evidence of teratogenicity.

 

There were no treatment-related effects on the histopathology of testes, ovaries or pituitary glands.

Applicant's summary and conclusion

Conclusions:

A conservative NOEL for reproductive toxicity over 5 consecutive generations and mating (F2A to F2E) is 5% 1,3-butanediol in the diet (approximately equivalent to 5000 mg/kg/day) may have been due to an unbalance diet and the presence of ketones.

Executive summary:

In a 5-generation reproductive toxicity study (which also evaluated teratogenic, dominant lethal and cytogenetic effects), 1,3-butanediol was fed continuously to groups of 25 rats/sex/group in the diet at dose levels of 0 (control), 5, 10 or 24 % by weight (0, 2600, 5200 and 1248 mg/kg bw/day, respectively).

Reproduction and lactation parameters were comparable to controls for 4 of the 5 generations for dams and pups. The pregnancy rates of F1A rats decreased during 5 successive mating cycles and no pups were born in the 24% dose level group in the F2E generation. Excluding this group, the viability of F2 generation pups revealed no significant differences between litters or between control and test groups.  No reason for the decrease in fertility index in the fifth generation was determined; however, controls were also affected but to a lesser degree. Besed on the available information, a conservative NOAEL for reproductive toxicity over 5 consecutive generations and 5 consecutive matings could be considered a 5% 1,3 -butanediol in the diet (approximately equivalent to 5000 mg/kg/day).