Octane-1,2-diol

Developmental toxicity / teratogenicity

Administrative data

Endpoint:

developmental toxicity

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2013

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 414 (Prenatal Developmental Toxicity Study)

Version / remarks:

of 2001

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Limit test:

no

Test material

Test material information

Constituent 1

Reference substance name:

Octane-1,2-diol

EC Number:

214-254-7

EC Name:

Octane-1,2-diol

Cas Number:

1117-86-8

Molecular formula:

C8H18O2

IUPAC Name:

octane-1,2-diol

Test animals

Species:

rat

Strain:

Wistar

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Species, Strain & Condition: Female Wistar rats, HsdHan: WIST rats
Day 0 pregnant rats, body weight 219 - 248 g
- Source: Advinus Therapeutics Ltd, in-house random bred (conventionally bred)
- Assignment to dose groups: At animal arrival bodyweight stratified randomization to ensure similar group mean bodyweights
- Housing:
Upon arrival: Mated females were housed individually in polysulfone cages with stainless steel grid
- Bedding material: steam sterilised corn cob
- Diet (ad libitum): Teklad Certified Global 14% protein rodent maintenance diet, pellets. Harlan 5800 AN Venray, The netherlands
- Water (ad libitum): Deep bore-well water passed through activated charcoal filter and exposed to UV rays

ENVIRONMENTAL CONDITIONS
The animals were housed in a single air-conditioned room maintained at (target ranges for temperature and relative humidity):
- Temperature (°C): 20-23°C
- Relative Humidity (%): 57-66%
- Photoperiod: 12 h day / 12 h night
- Rate of air exchange: 12 - 15 changes/h

Administration / exposure

Route of administration:

oral: gavage

Vehicle:

polyethylene glycol

Remarks:

PEG 300

Details on exposure:

- Dosing formulations (test material / vehicle mixtures) were prepared fresh every 3 to 4 days.

- Concentration in vehicle: The concentration of the test material in vehicle varied between dose groups thus allowing constant dosage volume in terms of mL/kg bw/day. Concentrations were 15, 30, 100 mg/ml vehicle.

- Amount (dose volume by gavage): 10 mL/kg bw/day.

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

For analysis of the test substance in the vehicle GC / FID was used with a DB-35 column (30 m long, 0.53 mm i.d., 0.5 μm film thickness). The analytical method was validated. The mean contents of the test substance in dose formulations were found to be well within the acceptance limit (within +/- 15%) of dose theoretical concentration; the relative standard deviation was equal to or less than 10%.

Details on mating procedure:

Females were received within several days at Gestation Day 0, i.e. the day positive evidence of mating was observed, and allocated to the treatment by body weight stratification.

Duration of treatment / exposure:

- Duration of treatment: Gestation Day 5 to 19 (to cover the period of organogenesis)
- Caesarian section and necropsy: On Gestation Day 20

Frequency of treatment:

Once daily

Duration of test:

20 days

Doses / concentrations

Doses / concentrations 1

Dose / conc.:

150 mg/kg bw/day (actual dose received)

Doses / concentrations 2

Dose / conc.:

300 mg/kg bw/day (actual dose received)

Doses / concentrations 3

Dose / conc.:

1 000 mg/kg bw/day (actual dose received)

No. of animals per sex per dose:

24

Control animals:

yes, concurrent vehicle

Details on study design:

Dose selection was based on the result of the 28 day study.

Examinations

Maternal examinations:

Clinical observations of dams: Twice daily during the normal working week, once daily at weekends
Body weight of dams: On Days 3, 5, 8, 11, 14, 17 and 20 of gestation
Food consumption of individual dams: For Days 0-3, 3-5, 5-8, 8-11, 11-14, 14-17 and 17-20 of gestation
Caesarean section and necropsy of dams: On Gestation Day 20, external observation and macroscopic examination of visceral organs

Ovaries and uterine content:

The ovaries and the gravid uterus were excised and immediately examined on Gestation Day 20.
Examinations included:
- Pregnancy status
- uterine weight
- Number of corpora lutea
- number of implantation sites
- number of early resorptions
- number of late resorptions

Fetal examinations:

- Number of fetuses, no. of viable fetuses, no. of non-viable fetuses
- Individual external examination of fetuses for gross abnormalities
- Individual fetus' examination of sex and weight (weight only of live fetuses)
- Examination of visceral malformations by modified Wilson's Razor Blade Sectioning Technique *
- Examination of skeletal malformations and bone development**, other half of each litter.

* after fixation in in 70% alcohol
** after fixation in 70% alcohol, evisceration, etc.and processing to 100% glycerol and staining with alizarin red S in Mall's solution.

Statistics:

The data on maternal body weight, body weight change, maternal food consumption, gravid uterus weight, number of corpora lutea, number of implantations, litter size, litter weight, male and female fetus number and fetal body weight were analyzed using ANOVA model, after testing for homogeneity for intra group variance using Levene’s test. When the intra group variances were heterogeneous, ANOVA was performed after suitable transformation of data. Dunnett’s pairwise comparison of the treated group means with the control group mean was performed if the group differences were found significant.
Incidence of pre-implantation loss, post implantation loss, number of early, late and total resorptions were analyzed using Kruskal Wallis.
Overall percentage of minor external, visceral and skeletal malformations, Sex ratio and number of dams with any resorptions were analyzed using 2 X 2 Contingency Table.

Indices:

- Mean number of corpora lutea (CL)/group: [Total no. of CL / Total no. of pregnant animals]
- Mean number of implantations/group: [Total no. of implantations / Total no. of pregnant animals]
- Percentage of early resorptions per group: [(No. of early resorptions / No. of implantations) x 100]
- Percentage of late resorptions per group: [(No. of late resorptions / No. of implantations) x 100]
- Pre-implantation loss (%): [(number of corpora lutea - number of implantations) / number of corpora lutea] x 100
- Post-implantation loss (%): [No. of (early + late) resorptions / number of implantations] x 100
- Sex ratio: [number of male foetuses : number of female foetuses]

Historical control data:

Included in the study report.

Results and discussion

Results: maternal animals

General toxicity (maternal animals)

Clinical signs:

no effects observed

Mortality:

no mortality observed

Body weight and weight changes:

effects observed, treatment-related

Description (incidence and severity):

mean maternal body weight and body weight gains were unaffected by the administration of the test substance. Mean corrected body weight gains were statistically significantly higher at all dose levels when compared to the control (61%, 57%, and 74% at 150, 300, and 1000 mg/kg bw/d, respectively). See attached Table on body weight in "Attached background material".

Food consumption and compound intake (if feeding study):

no effects observed

Description (incidence and severity):

See attached Table on food intake in "Attached background material".

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

Neuropathological findings:

not examined

Histopathological findings: non-neoplastic:

not examined

Other effects:

no effects observed

Maternal developmental toxicity

Number of abortions:

no effects observed

Pre- and post-implantation loss:

no effects observed

Description (incidence and severity):

See attached table on maternal developmental data in "Attached background material".

Total litter losses by resorption:

no effects observed

Description (incidence and severity):

See attached table on maternal developmental data in "Attached background material".

Early or late resorptions:

no effects observed

Description (incidence and severity):

See attached table on maternal developmental data in "Attached background material".

Dead fetuses:

no effects observed

Changes in pregnancy duration:

no effects observed

Changes in number of pregnant:

no effects observed

Other effects:

no effects observed

Details on maternal toxic effects:

Details on maternal toxic effects:
Body weight gain and food intake were unaffected by treatment. Mean corrected body weight gains were significantly higher at all dose levels compared to control animals. Mean gravid uterine weights were significantly reduced at 300 and 1000 mg/kg bw/day.
All other maternal parameters (mean number of corpora lutea, implantations, early and late resorptions, pre and post-implantation loss, number of dams with resorptions) remained unaffected in all treatment groups.

Effect levels (maternal animals)

1

Key result

Dose descriptor:

NOAEL

Effect level:

> 150 - < 300 mg/kg bw/day (actual dose received)

Based on:

test mat.

Basis for effect level:

other: maternal toxicity

2

Key result

Dose descriptor:

NOAEL

Effect level:

> 300 - < 1 000 mg/kg bw/day (actual dose received)

Based on:

test mat.

Basis for effect level:

other: developmental toxicity

Maternal abnormalities

Key result

Abnormalities:

no effects observed

Results (fetuses)

Fetal body weight changes:

effects observed, treatment-related

Description (incidence and severity):

See attached table with summary of litter data in "Attached background material".

Reduction in number of live offspring:

no effects observed

Description (incidence and severity):

See attached table with summary of litter data in "Attached background material".

Changes in sex ratio:

no effects observed

Description (incidence and severity):

See attached table with summary of litter data in "Attached background material".

Changes in litter size and weights:

effects observed, treatment-related

Description (incidence and severity):

no effects on litter size but on foetus weights, see attached table with summary of litter data in "Attached background material".

Changes in postnatal survival:

not examined

External malformations:

no effects observed

Skeletal malformations:

effects observed, treatment-related

Description (incidence and severity):

See attached table with skeletal observation data in "Attached background material".

Visceral malformations:

no effects observed

Other effects:

no effects observed

Details on embryotoxic / teratogenic effects:

Details on embryotoxic / teratogenic effects:
Mean fetus weights (both male and female) were significantly lower at all dose levels when compared to the vehicle control group. These values were within the historical control range at 150 and 300 mg/kg bw/day, but below the historical control range at 1000 mg/kg bw/day. Thus, this effect was considered treatment-related at 1000 mg/kg bw/day. The significantly increased incidence of a 14th accessory rib in fetuses at 1000 mg/kg bw/day was considered as sign of fetotoxicity due to the significant reduction of fetal weights at the same dose level. Teratogenic effects were not observed.
All other litter parameters (mean litter size, number of live fetuses, total number of fetuses and sex ratio) were comparable to the vehicle control group at all dose levels.

Effect levels (fetuses)

Key result

Dose descriptor:

NOAEL

Effect level:

> 300 - < 1 000 mg/kg bw/day (nominal)

Based on:

test mat.

Sex:

male/female

Basis for effect level:

changes in litter size and weights

Fetal abnormalities

Key result

Abnormalities:

effects observed, treatment-related

Localisation:

skeletal: supernumerary rib

other: reduced body weight, delayed development

Overall developmental toxicity

Key result

Developmental effects observed:

yes

Lowest effective dose / conc.:

1 000 mg/kg bw/day (actual dose received)

Treatment related:

yes

Relation to maternal toxicity:

developmental effects as a secondary non-specific consequence of maternal toxicity effects

Applicant's summary and conclusion

Conclusions:

Oral gavage administration of octane-1,2-diol to pregnant Wistar rats during gestation days 5 to 19 resulted in lower gravid uterine weight at doses of 300 and 1000 mg/kg bw/day. Fetuses at 1000 mg/kg bw/day had significantly lower body weights and a significantly increased incidence of a 14th accessory rib. These observations led to NOAELs of 150 mg/kg bw/day for maternal toxicity, of 300 mg/kg bw/day for developmental toxicity and of 1000 mg/kg bw/day for teratogenicity as no such potential was observed. As detailed in the discussion in the endpoint summary "Toxicity to reproduction" classification of octane-1,2-diol as reproductive toxicant is not considered appropriate.