1-aminopropan-2-ol

Developmental toxicity / teratogenicity

Administrative data

Endpoint:

developmental toxicity

Type of information:

experimental study

Adequacy of study:

key study

Study period:

Apr - Sep 2022

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2022

Report date:

2022

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 414 (Prenatal Developmental Toxicity Study)

Version / remarks:

June 2018

GLP compliance:

yes (incl. QA statement)

Test material

Test material information

Constituent 1

Reference substance name:

1-aminopropan-2-ol

EC Number:

201-162-7

EC Name:

1-aminopropan-2-ol

Cas Number:

78-96-6

Molecular formula:

C3H9NO

IUPAC Name:

1-aminopropan-2-ol

Specific details on test material used for the study:

No specific handling conditions required. The required amount of test item was weighed and dissolved in Elix water (w/w). The pH of the formulation was lowered to pH 7.9-8.1 using HCl. Formulations were prepared at least weekly, filled out in daily portions and stored in the refrigerator. Dosing formulations were removed from the refrigerator at least 30 minutes before dosing and were stirred at room temperature.

Test animals

Species:

rat

Strain:

Wistar

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Charles River Deutschland, Sulzfeld, Germany
- Females (if applicable): nulliparous, arrived on Day 0 or 1 post-coitum
- Age at study initiation: between 10-15 weeks old
- Weight at study initiation: 178 - 281 g females
- Fasting period before study: -
- Housing: Polycarbonate cages (Makrolon type MIII, height 18 cm) containing sterilized wooden fibers as bedding material (Lignocel S 8 15, JRS J.Rettenmaier & Söhne GmbH + CO. KG, Rosenberg, Germany) and enrichment and nesting material (paper and aspen wooden sticks), equipped with water bottles. Animals will be individually housed.
- Diet (e.g. ad libitum): pelleted rodent diet (SM R/M-Z from SSNIFF® Spezialdiäten GmbH, Soest,
Germany) ad libitum
- Water (e.g. ad libitum): yes. Municipal tap water
- Acclimation period: at least 5 days prior to the commencement of dosing
ENVIRONMENTAL CONDITIONS
- Temperature (°C): 20-24°C
- Humidity (%): 43-54% (target: 40-70%)
- Light Cycle: 12-hours light and 12-hours dark
- Ventilation: At least 10 air changes per hour.

IN-LIFE DATES: Initiation of Dosing: 25 Apr 2022, completion of In-life: 13 May 2022

Administration / exposure

Route of administration:

oral: gavage

Vehicle:

water

Details on exposure:

The dose volume for each animal were based on the most recent body weight measurement. The doses were given using a plastic feeding tube. The dose formulations were stirred continuously during dosing. Dose pot identification via Provantis was used as additional check to verify the dosing procedure according to Standard Operating Procedures.

PREPARATION OF DOSING SOLUTIONS:
- Formulations (w/w) homogenized to visually acceptable levels and pH set to 7.9-8.1 using 37% HCl (Merck, Darmstadt, Germany)
- Frequency of Preparation: At least weekly, filled out in daily portions and stored in the refrigerator.
- Storage Conditions Set to Maintain: 4°C
The dosing formulations will be removed from the refrigerator and stirred at room temperature for at least 30 minutes before dosing and dosed within 24 hours after removal from the refrigerator. Dose formulation samples will be collected for analysis.

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

Concentration and Homogeneity Analysis and Stability Analysis were performed using a validated analytical procedure (Test Facility Study No. 20316908).

Details on mating procedure:

time-mated.
Untreated females were mated at the Supplier and were at Day 0 or 1 post-coitum on arrival at the Test Facility (Day 0 post-coitum is the day of successful mating).

Duration of treatment / exposure:

Day 6 to Day 20 post-coitum.

Frequency of treatment:

Once daily

Doses / concentrations

Doses / concentrations 1

Dose / conc.:

0 mg/kg bw/day (nominal)

Doses / concentrations 2

Dose / conc.:

100 mg/kg bw/day (nominal)

Doses / concentrations 3

Dose / conc.:

300 mg/kg bw/day (nominal)

Doses / concentrations 4

Dose / conc.:

1 000 mg/kg bw/day (nominal)

No. of animals per sex per dose:

22

Control animals:

yes, concurrent vehicle

Details on study design:

- Dose selection rationale:
The dose levels were selected based on the results of the Dose Range Finder (Test Facility Study No. 20316909) and in an attempt to produce graded responses to the test material. Recorded test material-related changes in the DRF were considered not dose-limiting for the subsequent Main study. Therefore, selected dose levels for the Main study were 100, 300 and 1000 mg/kg bw/d.

Examinations

Maternal examinations:

CAGE SIDE OBSERVATIONS: Yes
- At least once daily (immediately after dosing) starting on Day 6 post coitum up to and including the day prior to necropsy.

DETAILED CLINICAL OBSERVATIONS: Yes
- On Days 2, 6, 15 and 21 post coitum

BODY WEIGHT: Yes
- On Days 2, 6, 9, 12, 15, 18 and 21 post-coitum.

FOOD CONSUMPTION: Yes
- Over Days 2-6, 6-9, 9-12, 12-15, 15-18 and 18-21 post coitum.

WATER CONSUMPTION: Yes
- Regular basis throughout the study.

POST-MORTEM EXAMINATIONS: Yes
- Sacrifice on gestation day # 21 post-coitum
- Necropsy (external examination, e.g. of ovaries and uterine horns, thyroid glands), Collection of Gross Lesions, Organ Weights (uteri, thyroid gland), Histology and Histopathology (thyroid gland)

Ovaries and uterine content:

yes
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 and distribution of live and dead fetuses; sex of each fetus based on the anogenital distance, if possible.

Blood sampling:

At day 21 post coitum, no fasting, for thyroid hormone measurement: Triiodothyronine (T3), Thyroxine (T4), Thyroid-Stimulating Hormone (TSH).

Fetal examinations:

External Examination, Body Weight, External Sex Determination, AGD Measurement

External, visceral, and skeletal findings were recorded as developmental variations (alterations in anatomic structure that are considered to have no significant biological effect on animal health or body conformity and/or represent slight deviations from normal) or malformations (those structural anomalies that alter general body conformity, disrupt or interfere with normal body function, or may be incompatible with life).

- External examinations: Yes: [all per litter], Each viable fetus was sexed, examined in detail to detect macroscopic visible abnormalities and their weight was determined. The anogenital distance (AGD) was measured for all viable fetuses. The AGD was normalized to the cube root of the fetal body weight.
- Soft tissue examinations: Yes: [half per litter] The sex of all fetuses was confirmed by internal examination and approximately one-half of the fetuses (live and dead) in each litter (all groups) were examined for visceral anomalies by dissection in the fresh (non-fixed) state. The thoracic and abdominal cavities were opened and dissected, including the heart and major vessels. Fetal kidneys were examined and graded for renal papillae development. The heads were removed from this one-half of the fetuses in each litter and placed in Bouin's solution for soft-tissue examination. After examination, the tissues without variations or malformations were discarded. Tissues with variations or malformations were stored in 10% formalin. Any remaining tissues (from the fetuses used for fresh visceral examination) were discarded. The carcasses were processed and stained (see described below) but were not examined in first instance.
- Skeletal examinations: Yes: [half per litter] All fetuses were eviscerated, followed by fixation in 96% aqueous ethanol, and maceration in potassium hydroxide. Thereafter, they were stained with Alizarin Red S. Subsequently, skeletal examination was done for one-half of the fetuses (i.e. the fetuses with heads). All specimens were archived in glycerin with bronopol as preservative. A few bones were not available for skeletal examination because they were accidentally damaged or lost during processing. The missing bones were listed in the raw data; evaluation by the fetal pathologist and Study Director determined there was no influence on the outcome of the individual or overall skeletal examinations, or on the integrity of the study as a whole.
- Head examinations: Yes: [half per litter], see soft tissue examination
- Anogenital distance of all live rodent pups: yes, normalized to the cube root of the fetal BW.

Statistics:

Any data collected during the (Pre)treatment Period are tabulated, summarized or statistically analyzed. All statistical analyses were performed within the respective study phase, unless otherwise noted. Numerical data collected on scheduled occasions were summarized and statistically analyzed as indicated below according to sex and occasion or by litter.
Means, standard deviations (or % coefficient of variation or standard error, when deemed appropriate), ratio, percentages, numbers, and/or incidences were reported as appropriate by dataset.

Indices:

Pregnancy Rate (%): No. of pregnant females x 100 / No. of mated females
Male Fetuses (%): No. of male fetuses x 100 / No. of fetuses
Female Fetuses (%): No. of female fetuses x 100 / No. of fetuses
Pre-Implantation Loss (%): No. of corpora lutea – No. of implantations x 100 / No. of corpora lutea
Post-Implantation Loss (%): No. of implantations – No. of live fetuses x 100 / No. of implantations
Litter % of Fetuses with Abnormalities: No. of fetuses in litter with a given finding x 100 / No. of fetuses in litter examined

Historical control data:

Historical data on thyroid hormone analyses and fetal pathology are available (see attached document below)

Results and discussion

Results: maternal animals

General toxicity (maternal animals)

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):

no effects observed

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

not examined

Ophthalmological findings:

not examined

Haematological findings:

not specified

Description (incidence and severity):

Serum levels of TSH were comparable to control values. Lower mean serum levels of total T4 at all dose levels were not statistically significant at 300 mg/kg bw/d and thus not dose-dependent. A statistically significant lower mean serum level of T3 was recorded at 1000 mg/kg bw/d. All mean values of T3 and T4 remained within the historical control data (see attachments below). Thus, this was considered as non-adverse.

Clinical biochemistry findings:

not examined

Endocrine findings:

not specified

Description (incidence and severity):

Serum levels of TSH were not statistically significantly different compared to control values. Lower mean serum levels of total T4 were noted at all dose levels (0.87, 0.89 and 0.85x of control at 100, 300 and 1000 mg/kg bw/d, respectively, not statistically significant at 300 mg/kg bw/d) and thus not dose-dependent. A statistically significant lower mean serum level of T3 (0.78x of control) was recorded at 1000 mg/kg bw/d. All mean values of T3 and T4 remained within the historical control data. As there were no weight changes and microscopic observations in the thyroid glands, this was considered as non-adverse.
(see attachments below)

Urinalysis findings:

not examined

Behaviour (functional findings):

not examined

Immunological findings:

not examined

Organ weight findings including organ / body weight ratios:

no effects observed

Description (incidence and severity):

There were no test material-related alterations in thyroid gland weights.

Gross pathological findings:

no effects observed

Neuropathological findings:

not examined

Histopathological findings: non-neoplastic:

no effects observed

Description (incidence and severity):

There were no test material-related microscopic observations in the thyroid glands.

Histopathological findings: neoplastic:

not examined

Other effects:

no effects observed

Details on results:

(see attached tables below)

Maternal developmental toxicity

Number of abortions:

no effects observed

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:

no effects observed

Changes in number of pregnant:

no effects observed

Description (incidence and severity):

A total of five females were non-gravid: Nos. 15 and 17 (control), No. 35 (100 mg/kg bw/d), No. 45 (300 mg/kg bw/d) and No. 82 (1000 mg/kg bw/d). Therefore, the number of females with viable litters available for evaluation was 20, 21, 21 and 21 in the control, 100, 300 and 1000 mg/kg bw/d groups, respectively.

Other effects:

no effects observed

Details on maternal toxic effects:

(see attached tables below)

Effect levels (maternal animals)

Dose descriptor:

NOAEL

Effect level:

1 000 mg/kg bw/day

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:

no effects observed

Reduction in number of live offspring:

no effects observed

Changes in sex ratio:

no effects observed

Changes in litter size and weights:

no effects observed

Anogenital distance of all rodent fetuses:

no effects observed

Changes in postnatal survival:

not examined

External malformations:

no effects observed

Skeletal malformations:

no effects observed

Visceral malformations:

no effects observed

Other effects:

no effects observed

Details on embryotoxic / teratogenic effects:

(see attached tables below)

Effect levels (fetuses)

Dose descriptor:

NOAEL

Effect level:

1 000 mg/kg bw/day

Based on:

test mat.

Sex:

male/female

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:

No maternal and developmental toxicity was observed up to the highest dose level tested.

Executive summary:

In a prenatal developmental toxicity study according to OECD test guideline 414, time-mated female Wistar Han rats were treated with 1-aminopropan-2-ol from Days 6 to 20 post coitum, inclusive, by daily oral gavage at dose levels of 100, 300 and 1000 mg/kg bw/d. The rats of the control group received the vehicle, Water (Elix), alone. No maternal and developmental toxicity was observed up to the highest dose level tested. Lower serum T4 levels were measured for all treatment groups, without statistical significance in the mid dose and additionally a lower serum T3 level was recorded at 1000 mg/kg bw/d. All group means remained within the available historical control data range. Further, no test material related changes in either serum TSH levels, thyroid gland weight or morphology were observed. Thus, the observed changes in serum T3 and T4 were considered not to represent an adverse effect of the test material.

In conclusion, the following maternal and developmental No Observed Adverse Effect Levels (NOAELs) for 1-aminopropan-2-ol were established: Maternal NOAEL: at least 1000 mg/kg bw/day. Developmental NOAEL: at least 1000 mg/kg bw/day.