2-hydroxy-1-[4-[4-(2-hydroxy-2-methylpropanoyl)phenoxy]phenyl]-2-methylpropan-1-one

Endpoint summary

Key value for chemical safety assessment

Toxic effect type:

dose-dependent

Effects on fertility

Link to relevant study records

Reference

Endpoint:

screening for reproductive / developmental toxicity

Type of information:

experimental study

Adequacy of study:

key study

Study period:

From January 28, 2021 to May 31, 2021

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 421 (Reproduction / Developmental Toxicity Screening Test)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Limit test:

no

Justification for study design:

The dose levels were selected by the Sponsor in consultation with the Study Director, based on the results from an OECD 407 repeated dose 28-day oral toxicity study performed in another laboratory and a Dose Range Finding (DRF) study performed at the Test Facility with the aim of inducing toxic effects but no death or suffering at the highest dose, and to obtain a No Adverse Effect Dose Level (NOAEL) at the lowest dose.

Species:

rat

Strain:

Wistar

Details on species / strain selection:

Species and strain: Han:WIST rats
Source: Toxi-Coop Zrt., H-1122 Budapest, Magyar Jakobinusok tere 4B
Hygienic level at supplier: SPF
Hygienic level during the study: Standard housing conditions
Sex: Male and female. The females were nulliparous and non-pregnant at the start of the study.
Age of animals: Young adult rats, approximately 12 weeks old at start of dosing and 14 weeks old at mating.
Body weight range: Males: 372 – 431 g, females: 231 – 266 g; did not exceed
± 20 % of the mean weight for each sex at onset of dosing.
Acclimation period: 12 days

Sex:

male/female

Details on test animals or test system and environmental conditions:

Animal health: Only healthy animals were used for the test. The health status was certified by the Veterinarian.
Housing: The animals were group-housed, up to 2 animals of the same sex/cage, with the exception of the mating and gestation/delivery/lactation period, when they were paired or individually housed (with pups), respectively.
Cage type: T3H polycarbonate
Bedding and nesting: “SAFE 3/4-S-FASERN” certified wooden chips (batch number: 03027201125, expiry date: 11 November 2023) produced by J. Rettenmaier & Söhne GmbH & Co.KG (Holzmühle 1, D-73494 Rosenberg, Germany) and “Sizzle pet” nest material (batch number: 491607, expiry date: 05 August 2023) produced by LBS (Serving Biotechnology) Ltd. (Unit 20, Gatwick Business Park, Kennel Lane, Hookwood, Surrey, RH6 0AH, United Kingdom) were available to animals during the study. Copies of the Certificates of Analyses are archived with the raw data.
Lighting period: 12 hours daily, from 6.00 a.m. to 6.00 p.m.
Temperature: 19 – 24 °C (target range 22 ± 3 °C)
Relative humidity: 31 – 57 % (target range 30-70 %)
Ventilation: 15-20 air exchanges/hour
Housing/Enrichment: Group housing allowed social interaction and the deep wood sawdust bedding allowed digging and other normal rodent activities. Nest building material allowed normal nesting behaviour. Fresh bedding was provided for the animals as frequently as appropriate/practical, but at least twice weekly.

Route of administration:

oral: gavage

Vehicle:

other: Methylcellulosum and aqua purificata (distilled water)

Details on exposure:

The test item was administered to the animals daily on a 7 days/week basis, by oral gavage using a tipped gavage needle attached to a syringe. A constant volume of 5 mL/kg bw was administered to all animals. The actual volume to be administered was calculated and adjusted based on each animal’s most recent body weight.

Dosing of both sexes began after 12 days acclimatisation and pre-exposure period (14 days), and it was performed 2 weeks before mating, during the mating, and was continued up to and including the day before the necropsy.

Details on mating procedure:

Mating began after the animals have attained full sexual maturity, 2 weeks after the initiation of dosing, with one female and one male (1:1 mating) in a single cage. Females remained with the same male until copulation occurred. A vaginal smear was prepared daily during the mating period and stained with 1 % aqueous methylene blue solution. The smear was examined with a light microscope. The presence of vaginal plug or sperm in the vaginal smear was considered as evidence of copulation (Day 0 of pregnancy). Sperm positive females were caged individually.

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

Concentration and homogeneity of the dosing formulations were determined three times during the study.
Based on the results, all test item formulations were shown to be homogeneous and they were found to be in the range of 92 to 101% of nominal concentrations. No test item was detected in the negative (vehicle) control sample. Based on these results, formulations were considered suitable for the study purposes.

Duration of treatment / exposure:

Parental males were dosed for 28 days (14 days pre-mating and 14 days mating/post-mating period).
Parental females were dosed for 14 days pre-mating, for up to 4 days during mating period, through gestation and up to and including the day before necropsy (13 days post-partum dosing).

Frequency of treatment:

Daily on a 7 days/week basis.

Dose / conc.:

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

Dose / conc.:

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

Dose / conc.:

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

Dose / conc.:

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

No. of animals per sex per dose:

12/sex/dose

Control animals:

yes, concurrent vehicle

Details on study design:

Male and female Wistar rats were treated for 2 weeks pre-mating and then during the mating/post-mating periods. This was 28 days in total for males. Females were treated throughout gestation and up to and including postpartum/lactation Day PPD13.
Parameters measured during the study included signs of morbidity and mortality twice daily, daily general observation or weekly detailed observation of clinical signs, weekly body weight and food consumption. In addition, the reproductive performance, pregnancy, parturition and postpartum/lactation period were monitored in the adult animals, and viability, clinical signs and development were evaluated in their F1 offsprings until PND13. At termination, necropsy with macroscopic examination was performed. Selected organs were weighed and/or preserved in appropriate fixatives from the adult animals. A detailed histological examination was performed on the selected list of retained organs in the Control and High dose groups. The thyroxine (T4) levels in the Day 13 pups and adult males were also assessed.

Parental animals: Observations and examinations:

At 100 mg/kg bw clinical symptoms were observed such as hunched back (3/12), piloerection (5/12) and slight decreased activity (1/12) in males and hunched back (2/12) in females.
At the high dose level of 100 mg/kg bw/day, body weight loss were observed both in male and female groups.

Oestrous cyclicity (parental animals):

No effect of test item on oestrus cycles was noted.

Litter observations:

There were no test item related differences in the offsprings body weights, anogenital distance or nipple retention and thyroid gland or T4 hormone levels.

Postmortem examinations (parental animals):

No treatment related macroscopic findings were noted at necropsy.
No test item related microscopic changes were observed in the investigated reproductive and other organs of the animals.

Reproductive indices:

There were no differences between the control and test item dosed groups with regard to reproductive ability, mating or gestation indices that could be ascribed to the test item administration.

Offspring viability indices:

There was no test item-related effect on mortality or survival of the pups.

Clinical signs:

effects observed, treatment-related

Description (incidence and severity):

Treatment at 100 mg/kg bw was associated with clinical symptoms such as hunched back (3/12), piloerection (5/12) and slight decreased activity (1/12) in males and hunched back (2/12) in females.

Dermal irritation (if dermal study):

not examined

Mortality:

no mortality observed

Body weight and weight changes:

effects observed, treatment-related

Description (incidence and severity):

At the high dose level of 100 mg/kg bw/day, statistically significant decrease of body weight were observed, both in male and female groups.

Food consumption and compound intake (if feeding study):

effects observed, treatment-related

Description (incidence and severity):

Test item related reduction of mean food consumption was observed during the first seven days of treatment in the high dose groups (p <0.05 for males and p < 0.01 for females).

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:

no effects observed

Histopathological findings: non-neoplastic:

no effects observed

Histopathological findings: neoplastic:

not examined

Other effects:

not examined

Reproductive function: oestrous cycle:

no effects observed

Reproductive function: sperm measures:

not examined

Reproductive performance:

no effects observed

Key result

Dose descriptor:

NOAEL

Effect level:

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

Based on:

test mat.

Sex:

male/female

Basis for effect level:

reproductive performance

Key result

Dose descriptor:

NOAEL

Effect level:

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

Based on:

test mat.

Sex:

male/female

Basis for effect level:

clinical signs

Key result

Critical effects observed:

no

Clinical signs:

no effects observed

Dermal irritation (if dermal study):

not examined

Mortality / viability:

no mortality observed

Body weight and weight changes:

no effects observed

Food consumption and compound intake (if feeding study):

not examined

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

Sexual maturation:

not examined

Anogenital distance (AGD):

no effects observed

Nipple retention in male pups:

no effects observed

Organ weight findings including organ / body weight ratios:

not examined

Gross pathological findings:

not examined

Histopathological findings:

not examined

Other effects:

not examined

Behaviour (functional findings):

not examined

Developmental immunotoxicity:

not examined

Key result

Dose descriptor:

NOAEL

Generation:

F1

Effect level:

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

Based on:

test mat.

Sex:

male/female

Basis for effect level:

viability

other: Development

Key result

Critical effects observed:

no

Key result

Reproductive effects observed:

no

Conclusions:

Under the study conditions, the parental systemic toxicity NOAEL was determined to be 30 mg/kg bw/day and the reproductive/developmental toxicity NOAEL was 100 mg/kg/ kg bw/day. The NOAEL for pup development and survival was 100 mg/kg bw/day.

Executive summary:

A screening study was conducted to determine the reproductive/developmental toxicity of the test substance according to OECD Guideline 421, in compliance with GLP. Parental male rats were exposed to the test substance once daily by oral gavage for 28 days (14 days pre-mating and 14 days mating/post-mating). Parental female rats were exposed daily for 14 days pre-mating, for up to 4 days during the mating period, through gestation and up to and including the day before necropsy (13 days post-partum). Test doses were 0, 10, 30 and 100 mg/kg bw/day. Accuracy and homogeneity of formulations were demonstrated by analyses.Treatment related clinical signs noted at 100 mg/kg bw/day consisted of hunched back (3/12), piloerection (5/12) and slight decreased activity (1/12) in males and hunched back (2/12) in females. No test substance related effect on oestrus cycle of parental females and in the reproductive parameters during mating and gestation, delivery and post-partum/lactation period until post=partum Day14 was noted.There were no adverse effects on F1 offspring viability, clinical signs, physical or sexual development. Under the study conditions, the parental systemic toxicity NOAEL was determined to be 30 mg/kg bw/day and the reproductive/developmental toxicity NOAEL was 100 mg/kg/ kg bw/day. The NOAEL for pup development and survival was 100 mg/kg bw/day (Rigó Kiss, 2021).

Effect on fertility: via oral route

Endpoint conclusion:

no adverse effect observed

Dose descriptor:

NOAEL

100 mg/kg bw/day

Study duration:

subacute

Species:

rat

Effect on fertility: via inhalation route

Endpoint conclusion:

no study available

Effect on fertility: via dermal route

Endpoint conclusion:

no study available

Additional information

A screening study was conducted to determine the reproductive/developmental toxicity of the test substance according to OECD Guideline 421, in compliance with GLP. Parental male rats were exposed to the test substance once daily by oral gavage for 28 days (14 days pre-mating and 14 days mating/post-mating). Parental females rats were exposed daily for 14 days pre-mating, for up to 4 days during the mating period, through gestation and up to and including the day before necropsy (13 days post-partum). Test doses were 0, 10, 30 and 100 mg/kg bw/day. Accuracy and homogeneity of formulations were demonstrated by analyses.Treatment-related clinical signs noted at 100 mg/kg bw/day consisted of hunched back (3/12), piloerection (5/12) and slight decreased activity (1/12) in males and hunched back (2/12) in females. No test substance related effect on oestrus cycle of parental females and in the reproductive parameters during mating and gestation, delivery and post-partum/lactation period until post partum Day14 was noted.There were no adverse effects on F1 offspring viability, clinical signs, physical or sexual development. Under the study conditions, the parental systemic toxicity NOAEL was determined to be 30 mg/kg bw/day and the reproductive/developmental toxicity NOAEL was 100 mg/kg/ kg bw/day. The NOAEL for pup development and survival was 100 mg/kg bw/day (Rigó Kiss, 2021).

Effects on developmental toxicity

Effect on developmental toxicity: via oral route

Endpoint conclusion:

no study available

Effect on developmental toxicity: via inhalation route

Endpoint conclusion:

no study available

Effect on developmental toxicity: via dermal route

Endpoint conclusion:

no study available

Justification for classification or non-classification

Based on the result of a reproductive/developmental screening study (OECD Guideline 421), the test substance does not warrant classification for this endpoint according to EU CLP criteria (Regulation 1272/2008/ EC).