3-(2,2-dimethyl-3-hydroxypropyl)toluene

Endpoint summary

Key value for chemical safety assessment

Toxic effect type:

dose-dependent

Effects on fertility

Description of key information

In a study according to OECD guideline 421, the NOAEL for general toxicity was considered to be 501.1 mg/kg bw/day for adult males and 1319.6 mg/kg bw/day for adult females. The NOAEL for reproductive toxicity was considered to be 994.3 mg/kg bw/day (males) or 1319.6 mg/kg bw/day (females) in adult animals. The NOAEL for developmental toxicity in pups was considered to be 663.9 mg/kg bw/day (mean maternal dose during lactation).

Link to relevant study records

Reference

Endpoint:

screening for reproductive / developmental toxicity

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2020-08-04 to 2021-01-11

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

other: Regulation on Test Methods for Chemical Substances, Notification No. 2019-23, National Institute of Environmental Research, Republic of Korea

Version / remarks:

2019-06-13

Deviations:

no

Qualifier:

according to guideline

Guideline:

OECD Guideline 421 (Reproduction / Developmental Toxicity Screening Test)

Version / remarks:

adopted 2016-06-29

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Limit test:

no

Species:

rat

Strain:

Sprague-Dawley

Remarks:

Crl:CD(SD), SPF

Details on species / strain selection:

Sprague-Dawley rats are commonly used in general toxicity studies, including reproductive and developmental toxicity studies, and large historical control data are available. In addition, the rat is a required species in the regulatory guidelines.

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Age at study initiation: (P) 11 weeks (males), 13 weeks (females)
- Weight at study initiation: (P) Males: 373.5-449.2; Females: 228.9-288.0 g
- Fasting period before study: Not specified
- Housing: Animals were housed in stainless wire mesh cages, 260W×350D×210H (mm) or polycarbonate cages, 260W×420D×180H (mm). One animal per cage was housed during the quarantine-acclimation period and the dosing period, one male and one female per cage were housed during the mating period and one female and neonates per cage was housed during the lactation period.
- Diet: Ad libitum
- Water: Ad libitum
- Acclimation period: Acclimation was stated but acclimation period not specified

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 19.8-22.8
- Humidity (%): 49.2-68.4
- Air changes (per hr): 10-15
- Photoperiod (hrs dark / hrs light): 12/12

IN-LIFE DATES: From day 1 to day 42 (males) and from day 1 to approx. day 50

Route of administration:

oral: feed

Vehicle:

acetone

Details on exposure:

PREPARATION OF DOSING SOLUTIONS:
Mixed test substance formulation (test substance in acetone) and powder feed were placed in feeders and provided ad libitum in the test substance groups.

DIET PREPARATION
- Rate of preparation of diet: Every 7-14 days
- Mixing appropriate amounts with: Powder feed rodent chow (LabDiet® CERTIFIED RODENT DIET 5002, powder type)
- Storage temperature of food: The feed was stable in a refrigerator for 14 days and at room temperature for 3-7 days.

VEHICLE
- Justification for use and choice of vehicle: Solubility properties

Details on mating procedure:

- M/F ratio per cage: One male and one female per cage
- Length of cohabitation: 2 weeks
- Proof of pregnancy: Vaginal plug or sperm in vaginal smear referred to as day 0 of pregnancy
- After successful mating each pregnant female was caged singly

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

Analysis for homogeneity and stability of the dosing formulations was conducted in a separate analytical method validation study. As a result, the dosing formulations comprising the dose levels of 0.1 and 2 % were confirmed to be homogenous and stable at room temperature for 3 and 7 days, respectively, and under refrigeration for 14 days. Analysis for concentration of the dosing formulations was conducted using gas chromatography. Analysis of the dosing formulations was conducted based on the method established in the same study referred to above. Samples were taken three times from the middle layer of each dosing formulation and analyzed once each for verification of dose concentration prior to the first dosing. As a result, the accuracies at 0.375, 0.75 and 1.5% were 91.44, 94.00 and 95.13% prior to dosing, respectively. These results were within the acceptable range (range: ±15% of nominal values).

Duration of treatment / exposure:

Prior to mating for 2 weeks, during 2 weeks of mating and 2 weeks post mating for total 42 days (males) and from 2 weeks prior to mating to day 13 post-partum (females)

Frequency of treatment:

Continuously

Dose / conc.:

1 319.6 mg/kg bw/day (actual dose received)

Remarks:

Calculated for females, corresponding to 1.5% in feed

Dose / conc.:

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

Remarks:

Calculated for males, corresponding to 1.5% in feed

Dose / conc.:

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

Remarks:

Calculated for females, corresponding to 0.75% in feed

Dose / conc.:

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

Remarks:

Calculated for males, corresponding to 0.75% in feed

Dose / conc.:

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

Remarks:

Calculated for females, corresponding to 0.375% in feed

Dose / conc.:

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

Remarks:

Calculated for males, corresponding to 0.375% in feed

Dose / conc.:

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

No. of animals per sex per dose:

10 animals per dose per group

Control animals:

yes, concurrent vehicle

Details on study design:

- Dose selection rationale: Doses were selected on the basis of a repeated dose 2-week dose range finding study (see section 7.5.1). In this study, doses of 0.5, 1 and 2% have been tested. No treatment-related changes in all examined items were observed in any doses tested and no deaths were observed at a dose of 2 %. Therefore, based on the result of this dose range finding study and after discussion with the sponsor, 1.5 % was selected as the high dose, and 0.75 and 0.375 % were selected as the mid and low doses, respectively, by applying a geometric ratio of 2.
- Fasting period before blood sampling for clinical biochemistry: More than 18 hours (except for pups)

Positive control:

Not included

Parental animals: Observations and examinations:

CAGE SIDE OBSERVATIONS: Yes
- Time schedule: Once daily for clinical signs and twice daily for mortality
- Cage side observations were not specified

DETAILED CLINICAL OBSERVATIONS: No data

BODY WEIGHT: Yes
- Time schedule for examinations:
Males: Just prior to dosing on day 1 (the first day of dosing), once a week throughout the dosing period, the day before necropsy and on the day of necropsy (fasted body weights).
Females: Prior to dosing on Day 1 (the first day of dosing), once a week throughout the dosing period (except mating period), on Gestation Days 0, 7, 14 and 20, on Postpartum Days 0, 4 and 13 and on the day of necropsy (fasted body weights).

FOOD CONSUMPTION AND COMPOUND INTAKE:
- Food consumption for each animal determined and mean daily diet consumption calculated as g food/kg body weight/day: Yes
- Compound intake calculated as time-weighted averages from the consumption and body weight gain data: No data

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

OTHER: Blood sampling
- Time schedule: Blood samples for thyroid hormone analysis were taken from all adult males and dams at termination

Oestrous cyclicity (parental animals):

The estrous cycle examination for females was conducted from dosing initiation day to confirmed copulation day and on the day of necropsy. Smears of vaginal mucosa were prepared in the morning daily. Prepared smears of vaginal mucosa were stained with Diff Quick stain. Stained vaginal mucosa smears were examined using light microscopy. The estrous cycle is divided into four stages; proestrus, estrus, metestrus and diestrus. One estrous cycle was defined as the period between the day of estrus and the day prior to next estrus. Estrous cycle was calculated from dosing initiation day to the day before mating.

Sperm parameters (parental animals):

Parameters examined in all P males:
Testis weight, epididymis weight, weight of prostate gland and seminal vesicle with coagulating gland, histopathological examination was carried out on the testis, epididymis in the control and high dose groups (especially focused on spermatogenesis and interstitial testicular cell structure)

Litter observations:

STANDARDISATION OF LITTERS
- Performed on day 4 postpartum: Yes
- If yes, maximum of 8 pups/litter (4/sex/litter as nearly as possible); excess pups were killed and discarded.

PARAMETERS EXAMINED
The following parameters were examined in F1 offspring:
number and sex of pups, stillbirths, live births, postnatal mortality, presence of gross anomalies, weight gain, anogenital distance (AGD), pup weight on the day of AGD, presence of nipples/areolae in male pups, total thyroxine (T4) analysis (if possible, from 1 male and 1 female pup on PND 4 and 13); particular attention was paid to the external reproductive genitals which were examined for signs of altered development

GROSS EXAMINATION OF DEAD PUPS:
Yes, for external abnormalities

ASSESSMENT OF DEVELOPMENTAL NEUROTOXICITY: No

ASSESSMENT OF DEVELOPMENTAL IMMUNOTOXICITY: No

Postmortem examinations (parental animals):

SACRIFICE
- Male animals: All surviving animals were sacrificed in day 43
- Maternal animals: All surviving animals were sacrified on post partum day 14. Non-delivered females were sacrificed on Gestation day 26.

GROSS NECROPSY
- Gross necropsy consisted of external and internal examinations (organs and tissues of the whole body)

HISTOPATHOLOGY / ORGAN WEIGHTS
The tissues indicated in Table 2 were prepared for microscopic examination. Organ weights of organs specified in table 1 were determined.

Postmortem examinations (offspring):

GROSS NECROPSY
- Gross necropsy consisted of external examinations

HISTOPATHOLOGY / ORGAN WEIGTHS
The tissues indicated in Table 2 were prepared for microscopic examination and tissues indicated in table 2 were weighed, respectively.

Statistics:

Statistical analysis was performed on the data of body weights, food consumption, estrous cycle, mating period, gestation period, post-implantation loss, body weights and birth and survival rates of pups, litter size, AGD index, nipple number, thyroid hormone value, external findings and organ weights using SAS program. The data was analyzed utilizing Bartlett’s test for homogeneity of variance (significance level: 0.05). One-way analysis of variance (ANOVA) was employed on homogeneous data (significance level: 0.05); then, if significant, Dunnett's test was applied for multiple comparisons (significance levels: 0.05 and 0.01, two-tailed). Kruskal-Wallis test was employed on heterogeneous data (significance level: 0.05); then, if significant, Steel’s test was applied for multiple comparisons (significance levels: 0.05 and 0.01, two-tailed). The data of mating index, fertility index and other data associated with gestation was analyzed utilizing Fisher’s exact test (significance levels: 0.05 and 0.01). For the data of external finding, Kruskal-Wallis test was employed (significance level: 0.05).

Reproductive indices:

Mating index (%), Mating period, Gestation period, Male fertility index (%), Female fertility index (%), Gestation index (%), Post-implantation loss rate (%)

Offspring viability indices:

Mean litter size, Live birth index (%), Viability index on postnatal day 0 (%), Viability index on postnatal day 4 (%), Sex ratio, AGD index

Clinical signs:

effects observed, non-treatment-related

Description (incidence and severity):

1.5% group: Loss of teeth accompanied by reddish tear, a decrease in food intake and decrease of fecal volume was observed in one male animal;

0.75% group: Reddish tear in 2 female animals, malocclusion in one female animal and soiled perineal region in one female animal;

0.375% group: Loss of teeth, malocclusion accompanied by reddish tear and decrease in food intake was observed in one female animal, soiled perineal region in one female animal

Dermal irritation (if dermal study):

not examined

Mortality:

no mortality observed

Body weight and weight changes:

effects observed, treatment-related

Description (incidence and severity):

1.5% group: Statistically significant decrease in body weight gain (-10.8 g, control: 27.1 g) was observed from day 1 to 8 in male animals

Food consumption and compound intake (if feeding study):

effects observed, treatment-related

Description (incidence and severity):

1.5% group: Statistically significant decrease in food consumption and relative food consumption was observed on day 4 in male animals (82.6% and 78.6% of control, respectively).

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:

no effects observed

Endocrine findings:

no effects observed

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:

no effects observed

Other effects:

no effects observed

Reproductive function: oestrous cycle:

no effects observed

Reproductive function: sperm measures:

no effects observed

Reproductive performance:

no effects observed

Key result

Dose descriptor:

NOAEL

Effect level:

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

Based on:

test mat.

Sex:

male

Remarks on result:

not determinable due to absence of adverse toxic effects

Remarks:

NOAEL for reproductive toxicity

Key result

Dose descriptor:

NOAEL

Effect level:

1 319.6 mg/kg bw/day (actual dose received)

Based on:

test mat.

Sex:

female

Remarks on result:

not determinable due to absence of adverse toxic effects

Key result

Dose descriptor:

NOAEL

Effect level:

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

Based on:

test mat.

Sex:

male

Basis for effect level:

body weight and weight gain

food consumption and compound intake

Remarks on result:

other: NOAEL for general toxicity

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:

effects observed, treatment-related

Description (incidence and severity):

1.5% group: A statistically significant decrease in body weights of pups males (81.9 and 86.4% of control, respectively) and pups females (81.2 and 85.4% of control, respectively) was observed on PNDs 4 and 13, respectively;

0.75% group: A non-significant decrease in body weights of male pups (90.6 and 92.8% of control) and female pups (91.7 and 92.4% of control) were observed on PNDs 4 and 13, respectively.

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:

effects observed, treatment-related

Description (incidence and severity):

1.5% group: A statistically significant decrease (70.0% and 60.4% of control, respectively) in thyroid hormone (T4) was observed on PND 13. This change was not correlated with observable changes of the thyroid gland in histopathological morphology, but was nevertheless considered to be a test substance-related effect as the value was outside the historical control range. Furthermore, increased liver weights of females in both the 2-week dose range finding study and in the 28-day repeated dose toxicity study (see section 7.5.1) indicate that liver effects are likely also be present in pups which may result in an impaired liver-thyroid interaction.

0.75% group: A statistically significant decrease (75.8% of control) in female pups of the 0.75% group was considered not to be a test substance-related effect since it was within the historical control range.

Urinalysis findings:

not examined

Sexual maturation:

no effects observed

Anogenital distance (AGD):

no effects observed

Nipple retention in male pups:

no effects observed

Organ weight findings including organ / body weight ratios:

no effects observed

Gross pathological findings:

no effects observed

Histopathological findings:

no effects observed

Other effects:

no effects observed

Description (incidence and severity):

No test substance-related changes in external findings of pups were observed in both sexes during the study.

Behaviour (functional findings):

not examined

Developmental immunotoxicity:

not examined

Key result

Dose descriptor:

NOAEL

Generation:

F1

Effect level:

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

Based on:

test mat.

Sex:

male/female

Basis for effect level:

body weight and weight gain

clinical biochemistry

Remarks on result:

other: The mean maternal dose during lactation in the 0.75% group (663.9 mg/kg/day) was used as NOAEL.

Key result

Critical effects observed:

no

Key result

Reproductive effects observed:

no

Conclusions:

In this study according to OECD guideline 421, the NOAEL for general toxicity was considered to be 501.1 mg/kg bw/day for adult males and 1319.6 mg/kg bw/day for adult females. The NOAEL for reproductive toxicity was considered to be 994.3 mg/kg bw/day (males) or 1319.6 mg/kg bw/day (females) in adult animals. The NOAEL for developmental toxicity in pups was considered to be 663.9 mg/kg bw/day (mean maternal dose during lactation).

Executive summary:

The purpose of this GLP compliant study according to OECD guideline 421 was to evaluate the effect of the test substance on male and female reproductive performance such as gonadal function, mating behavior, conception, development of conceptus, parturition and early postnatal development after oral (dietary) administration to male and female rats at dose levels of 0 (control), 0.375, 0.75 and 1.5 % (232.3, 501.1 and 994.3 mg/kg/day for males, and 325.1, 620.3 and 1319.6 mg/kg/day for females, respectively. Males were administered for 42 days and females were administered from 2 weeks prior to mating until day 13 post-partum. Also, some endocrine disruptor relevant endpoints were evaluated. No test-substance-related deaths or moribund animals occurred throughout the study. All animals survived until scheduled sacrifice. In clinical signs, reddish tear, nasal hemorrhage, decrease in food intake, decrease of fecal volume, soiled perineal region, malocclusion and loss of teeth were observed, but these signs were considered not to be test substance-related since they were observed at low incidence, were not dose-related, or were comparable to the control animals. In males of the 1.5% group, statistically significant decrease of body weight gain (-10.8 g, control: 27.1 g) was observed from day 1 to 8. In addition, statistically significant decreases of food consumption and relative food consumption (82.6% and 78.6% of control, respectively) were observed on day 4. These changes in body weight gain, food consumption and relative food consumption were considered to be test substance-related. No test substance-related changes were observed in the body weight, body weight gain, food consumption, relative food consumption and estrous cycle of adult female animals, thyroxine (T4) level in adult male animals and absolute and relative organ weights, necropsy and histopathological findings during the study. No test substance-related changes were observed in the reproduction function examination including mating index, mating period, gestation period and post-implantation loss rate during the study. A statistically significant decreased body weight in male and female pups of the 1.5% group was observed on PND 4 (81.9 and 81.2% of control, respectively) and PND 13 (86.4 and 85.4% of control, respectively). This effect was also considered to be connected to the increased substance intake in maternal animals (mean maternal dose during lactation was 1442.3 mg/kg/day) and may also be connected with the beginning of autonomous feed intake of pups, which starts approx. at PND 10. A statistically significant decrease in thyroxine (T4) was observed in male and female pups of the 1.5% group (70.0% and 60.4% of control, respectively) on PND 13. As this effect was not correlated with observable changes of the thyroid gland in histopathological morphology, it was not considered adverse but was rather considered as a general toxicity effect, resulting from increased substance uptake during lactation and beginning of substance uptake by feed. No liver weights were examined in this study, but results from a dose-range finding study which was conducted previous to this main study as well as results from a 28-day repeated dose feeding study showed significantly increased liver weights at approx. 750 mg/kg bw/day (males) and approx. 1500 mg/kg bw (males + females) (DRF) and at approx. 300 mg/kg bw (males) and approx. 1000 mg/kg bw (males + females) (28-day study). Since liver and thyroids interact closely, changes in T4 levels may be also connected to an increased metabolic capacity of the liver. No test substance-related changes were observed in pup data including external findings, anogenital distance, nipple number of male pups, and histopathological findings during the study. Based on the results of this study, the No-Observed-Adverse-Effect Level (NOAEL) for general toxicity was considered to be 0.75% for adult males (501.1 mg/kg bw/day) and 1.5% for adult females (1319.6 mg/kg/day). The NOAEL for reproductive toxicity was considered to be 1.5% in adult animals (994.3 mg/kg/day for males and 1319.6 mg/kg/day for females). The NOAEL for developmental toxicity in pups was considered to be 0.75%, corresponding to 620.3 mg/kg bw/day.

Effect on fertility: via oral route

Endpoint conclusion:

no adverse effect observed

Dose descriptor:

NOAEL

501.1 mg/kg bw/day

Study duration:

subacute

Species:

rat

Quality of whole database:

Reliable without restrictions

Effect on fertility: via inhalation route

Endpoint conclusion:

no study available

Effect on fertility: via dermal route

Endpoint conclusion:

no study available

Additional information

Reproduction/Developmental Toxicity Screening Test, rat, RL1

The purpose of this GLP compliant study according to OECD guideline 421 was to evaluate the effect of the test substance on male and female reproductive performance such as gonadal function, mating behavior, conception, development of conceptus, parturition and early postnatal development after oral (dietary) administration to male and female rats at dose levels of 0 (control), 0.375, 0.75 and 1.5 % (232.3, 501.1 and 994.3 mg/kg/day for males, and 325.1, 620.3 and 1319.6 mg/kg/day for females, respectively. Doses were chosen based on results of a range finding study (see section 7.5.1) where the highest dose of 2% (achieved concentrations: 1435.5 mg/kg bw/day in females and 1572.8 mg/kg bw/day in males) induced no serious toxicological effects. Males were administered for 42 days and females were administered from 2 weeks prior to mating until day 13 post-partum. Also, some endocrine disruptor relevant endpoints were evaluated. No test-substance-related deaths or moribund animals occurred throughout the study. All animals survived until scheduled sacrifice. In clinical signs, reddish tear, nasal hemorrhage, decrease in food intake, decrease of fecal volume, soiled perineal region, malocclusion and loss of teeth were observed, but these signs were considered not to be test substance-related since they were observed at low incidence, were not dose-related, or were comparable to the control animals. In males of the 1.5% group, statistically significant decrease of body weight gain (-10.8 g, control: 27.1 g) was observed from day 1 to 8. In addition, statistically significant decreases of food consumption and relative food consumption (82.6% and 78.6% of control, respectively) were observed on day 4. These changes in body weight gain, food consumption and relative food consumption were considered to be test substance-related. No test substance-related changes were observed in the body weight, body weight gain, food consumption, relative food consumption and estrous cycle of adult female animals, thyroxine (T4) level in adult male animals and absolute and relative organ weights, necropsy and histopathological findings during the study. No test substance-related changes were observed in the reproduction function examination including mating index, mating period, gestation period and post-implantation loss rate during the study. A statistically significant decreased body weight in male and female pups of the 1.5% group was observed on PND 4 (81.9 and 81.2% of control, respectively) and PND 13 (86.4 and 85.4% of control, respectively). This effect was also considered to be connected to the increased substance intake in maternal animals (mean maternal dose during lactation was 1442.3 mg/kg/day) and may also be connected with the beginning of autonomous feed intake of pups, which starts approx. at PND 10. A statistically significant decrease in thyroxine (T4) was observed in male and female pups of the 1.5% group (70.0% and 60.4% of control, respectively) on PND 13. As this effect was not correlated with observable changes of the thyroid gland in histopathological morphology, it was not considered adverse but was rather considered as a general toxicity effect, resulting from increased substance uptake during lactation and beginning of substance uptake by feed. No liver weights were examined in this study, but results from a dose-range finding study which was conducted previous to this main study as well as results from a 28-day repeated dose feeding study showed significantly increased liver weights at approx. 750 mg/kg bw/day (males) and approx. 1500 mg/kg bw (males + females) (DRF) and at approx. 300 mg/kg bw (males) and approx. 1000 mg/kg bw (males + females) (28-day study). Since liver and thyroids interact closely, changes in T4 levels may be also connected to an increased metabolic capacity of the liver. No test substance-related changes were observed in pup data including external findings, anogenital distance, nipple number of male pups, and histopathological findings during the study. Based on the results of this study, the No-Observed-Adverse-Effect Level (NOAEL) for general toxicity was considered to be 0.75% for adult males (501.1 mg/kg bw/day) and 1.5% for adult females (1319.6 mg/kg/day). The NOAEL for reproductive toxicity was considered to be 1.5% in adult animals (994.3 mg/kg/day for males and 1319.6 mg/kg/day for females). The NOAEL for developmental toxicity in pups was considered to be 0.75%, corresponding to 620.3 mg/kg bw/day.

Effects on developmental toxicity

Description of key information

In a reproduction/developmental screening study according to OECD guideline 421 (see section 7.8.1), the NOAEL for general toxicity was considered to be 1319.6 mg/kg bw/day for adult females. The NOAEL for developmental toxicity in pups was considered to be 663.9 mg/kg bw/day (mean maternal dose during lactation).

Effect on developmental toxicity: via oral route

Endpoint conclusion:

no adverse effect observed

Dose descriptor:

NOAEL

Study duration:

subacute

Species:

rat

Quality of whole database:

Reliable without restrictions

Effect on developmental toxicity: via inhalation route

Endpoint conclusion:

no study available

Effect on developmental toxicity: via dermal route

Endpoint conclusion:

no study available

Additional information

Reproduction/Developmental Toxicity Screening Test, rat, RL1 (see section 7.8.1)

The purpose of this GLP compliant study according to OECD guideline 421 was to evaluate the effect of the test substance on male and female reproductive performance such as gonadal function, mating behavior, conception, development of conceptus, parturition and early postnatal development after oral (dietary) administration to male and female rats at dose levels of 0 (control), 0.375, 0.75 and 1.5 % (232.3, 501.1 and 994.3 mg/kg/day for males, and 325.1, 620.3 and 1319.6 mg/kg/day for females, respectively. Doses were chosen based on results of a range finding study (see section 7.5.1) where the highest dose of 2% (achieved concentrations: 1435.5 mg/kg bw/day in females and 1572.8 mg/kg bw/day in males) induced no serious toxicological effects. Males were administered for 42 days and females were administered from 2 weeks prior to mating until day 13 post-partum. Also, some endocrine disruptor relevant endpoints were evaluated. No test-substance-related deaths or moribund animals occurred throughout the study. All animals survived until scheduled sacrifice. In clinical signs, reddish tear, nasal hemorrhage, decrease in food intake, decrease of fecal volume, soiled perineal region, malocclusion and loss of teeth were observed, but these signs were considered not to be test substance-related since they were observed at low incidence, were not dose-related, or were comparable to the control animals. In males of the 1.5% group, statistically significant decrease of body weight gain (-10.8 g, control: 27.1 g) was observed from day 1 to 8. In addition, statistically significant decreases of food consumption and relative food consumption (82.6% and 78.6% of control, respectively) were observed on day 4. These changes in body weight gain, food consumption and relative food consumption were considered to be test substance-related. No test substance-related changes were observed in the body weight, body weight gain, food consumption, relative food consumption and estrous cycle of adult female animals, thyroxine (T4) level in adult male animals and absolute and relative organ weights, necropsy and histopathological findings during the study. No test substance-related changes were observed in the reproduction function examination including mating index, mating period, gestation period and post-implantation loss rate during the study. A statistically significant decreased body weight in male and female pups of the 1.5% group was observed on PND 4 (81.9 and 81.2% of control, respectively) and PND 13 (86.4 and 85.4% of control, respectively). This effect was also considered to be connected to the increased substance intake in maternal animals (mean maternal dose during lactation was 1442.3 mg/kg/day) and may also be connected with the beginning of autonomous feed intake of pups, which starts approx. at PND 10. A statistically significant decrease in thyroxine (T4) was observed in male and female pups of the 1.5% group (70.0% and 60.4% of control, respectively) on PND 13. As this effect was not correlated with observable changes of the thyroid gland in histopathological morphology, it was not considered adverse but was rather considered as a general toxicity effect, resulting from increased substance uptake during lactation and beginning of substance uptake by feed. No liver weights were examined in this study, but results from a dose-range finding study which was conducted previous to this main study as well as results from a 28-day repeated dose feeding study showed significantly increased liver weights at approx. 750 mg/kg bw/day (males) and approx. 1500 mg/kg bw (males + females) (DRF) and at approx. 300 mg/kg bw (males) and approx. 1000 mg/kg bw (males + females) (28-day study). Since liver and thyroids interact closely, changes in T4 levels may be also connected to an increased metabolic capacity of the liver. No test substance-related changes were observed in pup data including external findings, anogenital distance, nipple number of male pups, and histopathological findings during the study. Based on the results of this study, the No-Observed-Adverse-Effect Level (NOAEL) for general toxicity was considered to be 0.75% for adult males (501.1 mg/kg bw/day) and 1.5% for adult females (1319.6 mg/kg/day). The NOAEL for reproductive toxicity was considered to be 1.5% in adult animals (994.3 mg/kg/day for males and 1319.6 mg/kg/day for females). The NOAEL for developmental toxicity in pups was considered to be 0.75%, corresponding to 620.3 mg/kg bw/day.

Justification for classification or non-classification

Classification, Labeling, and Packaging Regulation (EC) No 1272/2008

The available experimental test data are reliable and sufficient for classification purposes according to Regulation (EC) No 1272/2008 (CLP). Thus, the test item is not classfied for reproductive toxicity according to Regulation (EC) No 1272/2008, as amended for seventeenth time in Regulation (EU) No 2021/849.