Guerbet alcohols, C24-26, branched and cyclic

Developmental toxicity / teratogenicity

Administrative data

Endpoint:

developmental toxicity

Type of information:

experimental study

Adequacy of study:

key study

Study period:

January to October 2020

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Justification for type of information:

This study was performed for the notification in other regions where authorities do not accept read-across data.

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2020

Report date:

2020

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 414 (Prenatal Developmental Toxicity Study)

Version / remarks:

June 25, 2018

Deviations:

no

GLP compliance:

yes

Limit test:

no

Test material

Test material information

Constituent 1

Reference substance name:

Guerbet alcohols, C24-26, branched and cyclic

EC Number:

942-520-9

Cas Number:

2041102-78-5

Molecular formula:

not applicable, UVCB

IUPAC Name:

Guerbet alcohols, C24-26, branched and cyclic

Test material form:

liquid

Test animals

Species:

rat

Strain:

Sprague-Dawley

Administration / exposure

Route of administration:

oral: gavage

Vehicle:

corn oil

Details on exposure:

PREPARATION OF DOSING SOLUTIONS: The required amount of test item was suspended in the vehicle. The formulation was prepared daily or weekly according to stability data. Concentrations were calculated and expressed in terms of test item as supplied.
VEHICLE- Justification for use and choice of vehicle (if other than water):
- Concentration in vehicle: 20, 60 and 200 mg/mL
- Amount of vehicle (if gavage): 5 ml/kg

Details on analytical verification of doses or concentrations:

Analysis were performed in a separate study in order to validate the analytical method and the formulation procedure and to verify the stability of the formulations. Samples of the formulations prepared during the current study (the first and the last week of treatment )

Details on mating procedure:

The females were paired with male rats. Females were paired one to one in the home cage of the male and left overnight. Vaginal smears were taken daily in themorning from the day after pairing until a positive identification of mating was made. The day of mating, as judged by the presence of spermin the vaginal smear or by the presence of a copulation plug, was considered as Day 0 of gestation (or Day 0 post coitum). Full mating records were maintained.

Duration of treatment / exposure:

All animals were dosed from Day 3 through Day 19 post coitum.

Frequency of treatment:

once a day

Doses / concentrations

Doses / concentrations 1

Dose / conc.:

100 mg/kg bw/day

Doses / concentrations 2

Dose / conc.:

300 mg/kg bw/day

Doses / concentrations 3

Dose / conc.:

1 000 mg/kg bw/day

No. of animals per sex per dose:

25 mated females

Control animals:

yes, concurrent vehicle

Details on study design:

- Dose selection rationale: Dose levels have been selected based on a previous GLP subchronic toxiicty study.

Examinations

Maternal examinations:

CAGE SIDE OBSERVATIONS: Yes
- Time schedule: daily in the morning and in the afternoon (during the weekend: morning and mid-day)

DETAILED CLINICAL OBSERVATIONS: Yes
- Time schedule: daily

BODY WEIGHT: Yes
- Time schedule for examinations: on Days 0, 3, 6, 9, 12, 15, 18 and 20 post coitum.

FOOD CONSUMPTION AND COMPOUND INTAKE (if feeding study): Yes on Days 3, 6, 9, 12, 15, 18 and 20 post coitum starting
from Day 0 post coitum
- Food consumption for each animal determined and mean daily diet consumption calculated as g food/animal/day: Yes
- Compound intake calculated as time-weighted averages from the consumption and body weight gain data: No

WATER CONSUMPTION AND COMPOUND INTAKE (if drinking water study): No

POST-MORTEM EXAMINATIONS: Yes
- Sacrifice on gestation day 20 post coitum
- Organs examined: thyroid

Other: Thyroid hormone determination (T3, T4, TSH)

Ovaries and uterine content:

The ovaries and uterine content was examined after termination: Yes
Examinations included:
- Gravid uterus weight: Yes
- Number of corpora lutea: Yes
- Number of implantations: Yes
- Number of early resorptions: Yes
- Number of late resorptions: Yes

Other:
- number, sex and weight of all live foetuses;
– number and sex of dead foetuses (foetuses at termwithout spontaneous movements
and breathing);
– number of intra-uterine deaths;
– gross evaluation of placentae.

Fetal examinations:

- External examinations: Yes: all per litter
- Soft tissue examinations: Yes: half per litter
- Skeletal examinations: Yes: half per litter
- Head examinations: Yes: No data

Statistics:

For continuous variables the significance of the differences amongst group means was assessed by Dunnett’s test or a modified t test, depending on the homogeneity of data. Statistical analysis of non-continuous variables was carried out by means of the Kruskal-Wallis test and intergroup differences between the control and treated groups assessed by a non-parametric version of theWilliams test. Statistical analysis of histopathological findings was carried out by means of the non-parametric Kolmogorov-Smirnov test if n was more than 5.

Indices:

Pre-implantation loss was calculated as a percentage from the formula:

Pre impl. Loss%= (no. of corpora lutea−no. of implantations)/no. of corpora lutea ×100

Post-implantation loss was calculated as a percentage from the formula:

Post impl. Loss%=(no. of implantations−no. of live foetuses)/no. of implantations×100

Total implantation loss was calculated as a percentage from the formula:
Total impl. Loss%=(no. of corpora lutea−no. of live foetuses)/no. of corpora lutea×100

Sex ratios of the foetuses were calculated as the percentage of males per litter.

Results and discussion

Results: maternal animals

General toxicity (maternal animals)

Clinical signs:

effects observed, non-treatment-related

Description (incidence and severity):

Minor signs, such as scabs, hairloss and damaged ear were sporadically recorded during the study. These findings were considered as incidental.

Dermal irritation (if dermal study):

effects observed, non-treatment-related

Description (incidence and severity):

Minor signs, such as scabs, were sporadically recorded during the study. These findings were considered as incidental.

Mortality:

mortality observed, non-treatment-related

Description (incidence):

One low dose female died on Day 20 post coitum, immediately after the blood collection. No signs were noted during the in vivo phase and no relevant changes were observed at micro- and macroscopic observations. The cause of death was considered due to the bleeding procedure.

Body weight and weight changes:

no effects observed

Food consumption and compound intake (if feeding study):

effects observed, non-treatment-related

Description (incidence and severity):

No relevant differences in food consumption were noted between control and treated females. A slight statistically significant increase (12%) recorded in high dose females on Day 20 post coitum was considered incidental and not adverse.

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:

no effects observed

Description (incidence and severity):

No changes were recorded between control and treated groups in thyroid stimulating hormone (TSH), triiodothyronine (T3) and thyroxine (T4) determinations.

Organ weight findings including organ / body weight ratios:

effects observed, non-treatment-related

Description (incidence and severity):

The statistically significant decrease (approximately 18%) of relative thyroid weight (% to terminal body weight) observed in the high dose group compared to controls was not explained by the evaluation of the thyroid histopathological data. Furthermore, considering that the terminal body weight of females was influenced by their state of pregnancy (pregnant, not-pregnant, different number of foetuses), no toxicological significance could be attributed to this change.

Gross pathological findings:

no effects observed

Description (incidence and severity):

No treatment-related changes were noted in the females that completed the treatment period, following gross pathology examination. All observed changes were considered spontaneous and incidental, having a comparable incidence in control and treated groups and/or are characteristically seen in untreated Sprague Dawley SD rats of the same age.

Neuropathological findings:

not examined

Histopathological findings: non-neoplastic:

no effects observed

Histopathological findings: neoplastic:

no effects observed

Other effects:

no effects observed

Maternal developmental toxicity

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:

no effects observed

Changes in pregnancy duration:

not examined

Changes in number of pregnant:

no effects observed

Other effects:

no effects observed

Effect levels (maternal animals)

Dose descriptor:

NOAEL

Effect level:

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

Based on:

test mat.

Remarks on result:

not determinable due to absence of adverse toxic effects

Maternal abnormalities

Abnormalities:

no effects observed

Results (fetuses)

Fetal body weight changes:

effects observed, non-treatment-related

Description (incidence and severity):

A total of 7 small foetuses (< 2.7 g) were detected: 2 out of 318 in the control group, 1 out of 327 in the low dose group, 1 out of 356 in the mid-dose group and 3 out of 391 in the high dose group. No treatment-related abnormalities or malformations were noted.

Reduction in number of live offspring:

not examined

Changes in sex ratio:

no effects observed

Changes in litter size and weights:

no effects observed

Changes in postnatal survival:

not examined

External malformations:

no effects observed

Skeletal malformations:

effects observed, non-treatment-related

Description (incidence and severity):

A total of 8 foetuses showed skeletal malformations:

– In Group 1, one foetus with cleft palate and no ossification of ischium and pubis
– In Group 2, one foetus, with pubis no ossification, one foetus with absence of digits and ischium and pubis non ossification, one foetus with presphenoid of skull no ossification and another foetus with absence of digits
– In Group 3, one foetus and two other foetuses with pubis no ossification.

Taken into account that pubis unossified was mainly observed in small foetuses (foetal weight < 2.7 g), that the litter incidence of malformations was similar to controls and that no foetuses were affected in the high dose group, they were considered incidental, as well as the other alterations (anomalies and variations) recorded.

Visceral malformations:

effects observed, non-treatment-related

Description (incidence and severity):

A total of 5 foetuses showed malformations:

– In Group 1, one foetus (dam no. X1210035) with unilateral microphtalmia
– In Group 2, one foetus (dam no. X1210097) with brain bilateral ventricles enlarged extreme
– In Group 3, one foetus with unilateral pelvic dilatation extreme
– In Group 4, one foetus with malformation of heart and great vessels (dextrocardia,absence of aortic arch and subclavian artery) and another foetus with brain bilateral ventricles enlarged extreme.

These findings, as well as the other alterations (anomalies and variations) were considered incidental and not treatment-related, having a comparable distribution between groups, with a quite similar incidence in termof number of foetuses affected.

Other effects:

no effects observed

Effect levels (fetuses)

Dose descriptor:

NOAEL

Effect level:

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

Based on:

test mat.

Remarks on result:

not determinable due to absence of adverse toxic effects

Fetal abnormalities

Abnormalities:

no effects observed

Overall developmental toxicity

Developmental effects observed:

no

Applicant's summary and conclusion

Conclusions:

On the basis of the results obtained in this study, the high dose level (1000 mg/kg bw/day) was considered the NOAEL (No Observed Adverse Effect Level) for maternal toxicity and developmental toxicity of Guerbet alcohols, C24-26, branched and cyclic.

Executive summary:

The effects of Guerbet alcohols, C24-26, branched and cyclic, were investigated after oral administration in female rats during pregnancy and on embryo-foetal development. Doses of 0., 100 , 300 and 1000 mg/kg bw/d were administered. All animals were administered during the gestation period, starting from Day 3 through Day 19 post coitum at the dosing volume of 5 mL/kg. Body weight, daily clinical signs and food consumption were recorded during the in vivo phase. All females were caesarean-sectioned on Day 20 post coitum and subjected to post mortem examination. Blood collection for hormone determination in association to determination of the thyroid weight from all females were performed onDay 20 post coitum. The number of corpora lutea, implantations, early and late intrauterine deaths, live and dead foetuses, uterus weight, foetal weight and sex were recorded. All foetuses were examined for external abnormalities. The anogenital distance (AGD) in all live foetuses were recorded. Approximately one half of the foetuses in each litter was examined for fixed-visceral and skeletal abnormalities. One female of Group 2 died on Day 20 post coitum, immediately after the blood collection. The cause of death could be considered related to the bleeding procedure. A total of 6 females were found not pregnant at necropsy: 3 in the control group, 2 in the low dose group and 1 in the mid-dose group. The number of females with live foetuses on Day 20 post coitum was: 22 in the control and low dose groups, 24 in the mid-dose group and 25 in the high dose group. No adverse clinical signs were observed throughout the study both in control and treated females. Body weight and body weight gain were unaffected by treatment. No relevant differences in food consumption were noted between control and treated females. No changes were recorded between control and treated groups in the levels of TSH, T3 and T4. Terminal bodyweight, uterusweight and absoluteweight gainwere unaffected by treatment. Litter data and sex ratios were unaffected by treatment. No treatment-related differences were noted in the mean values of the anogenital distance of foetuses of both sexes maternally exposed at all dose levels compared to the control group. No treatment-related changes were observed in the absolute and relative thyroid weight of treated females, when compared to control data. A single female animal from the low dose group was found dead on Day 20 of gestation. No relevant changes were observed at micro- and macroscopic observations. The pathological picture of this animal did not allow to establish the cause of death. Females that completed the treatment period did not show relevant macroscopic changes that could be considered treatment-related. No treatment-related findings were noted in the microscopic evaluation of the thyroid gland of treated females when compared to the controls. No treatment-related findings were noted at the external examination of foetuses. Malformations of part of the skeleton were recorded in control (one foetus), low (four foetuses) and mid- dose groups (three foetuses). Taken into account that pubis and ischium unossified were mainly observed in small foetuses (foetal weight < 2.7 g) and with a litter incidence similar to controls and that no foetuses were affected in the high dose group, these major alteration were considered incidental, as well as the other minor alterations (anomalies and variations) recorded. Major alterations of soft tissueswere recorded in control and treated groups. These findings, as well as the other minor alterations (anomalies and variations)were considered incidental and not treatment-related, having a comparable distribution between groups, with a quite similar incidence in termof number of foetuses affected.

On the basis of the results obtained in this study, the high dose level (1000 mg/kg bw/day) was considered the NOAEL (No Observed Adverse Effect Level) for maternal toxicity and developmental toxicity.