Reaction mass of [3-(trimethoxysilyl) propyl]urea, [3-(dimethoxyethoxysilyl) propyl]urea, [3-(methoxydiethoxysilyl) propyl]urea and [3-(triethoxysilyl) propyl]urea.

Endpoint summary

Key value for chemical safety assessment

Effects on fertility

Description of key information

No extended one-generation study is needed as no effects on reproductive organs are observed in a 90-day repeated dose toxicity study.

Link to relevant study records

Reference

Endpoint:

extended one-generation reproductive toxicity - basic test design (Cohorts 1A, and 1B without extension)

Data waiving:

study scientifically not necessary / other information available

Justification for data waiving:

other:

Reason / purpose for cross-reference:

data waiving: supporting information

Effect on fertility: via oral route

Endpoint conclusion:

no study available

Effect on fertility: via inhalation route

Endpoint conclusion:

no study available

Effect on fertility: via dermal route

Endpoint conclusion:

no study available

Additional information

In an OECD 408 study that was compliant with GLP, the test item was administered daily in graduated doses (100, 300, or 1000 mg/kg bw/day) to 3 groups for a treatment period of 90 days (Eurofins, 2018). Animals in the additional control group were handled identically to the dose groups but received aqua ad injectionem. The 4 groups were comprised of 10 male and 10 female Wistar rats each.

 

To evaluate the possible toxic effects on fertility, the estrous cycle was examined at defined time points during the treatment and recovery period. Epididymal sperm motility and testicular sperm count was analyzed at the end of the treatment and recovery period. Sperm morphology from vas deferens was evaluated during the treatment of control and high dose males. There was statistically significant lower relative (to body weight) epididymides weight in high-dose recovery males. This effect on organ weights in high-dose male recovery animals was not considered to be test item related as no such effect was observed in animals sacrificed at the end of treatment period. Reproductive measures, including sperm motility or testicular sperm count and estrous cycle, also were not affected by treatment. Based on histopathological evaluation, gross lesions were unremarkable and not related to treatment with the test item and assumed to be common background findings in this strain.

Effects on developmental toxicity

Description of key information

Developmental study (OECD TG 414, GLP): NOAEL = 1000 mg/kg/bw/day (highest dose tested)

Link to relevant study records

Reference

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

Qualifier:

according to guideline

Guideline:

OECD Guideline 414 (Prenatal Developmental Toxicity Study)

Version / remarks:

22 January, 2001

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Remarks:

Bayerisches Landesamt für Gesundheit und Lebensmittelsicherheit

Limit test:

no

Species:

rat

Strain:

Wistar

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Charles River, 97633 Sulzfeld, Germany
- Age at study initiation: approx. 11-12 weeks old
- Weight at study initiation: males: 318 - 361 g; females: 194 - 238 g
- Housing: The animals were kept individually in IVC cages (type III H, polysulphone cages) on Altromin saw fibre bedding (except during the pre-mating period when females were kept in groups of two animals and during mating period when two females were paired with one male). During the pre-mating period and after mating, males were housed in groups (2 animals / cage) in IVC cages.
- Diet: Altromin 1324 maintenance diet for rats and mice provided ad libitum
- Water: tap water, sulphur acidified to a pH of approximately 2.8 (drinking water, municipal residue control, microbiological controls at regular intervals) provided ad libitum
- Acclimation period: 5 days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 22 ± 3
- Humidity (%): 55 ± 10
- Air changes (per hr): 10
- Photoperiod (hrs dark / hrs light): 12/12

Route of administration:

oral: gavage

Vehicle:

unchanged (no vehicle)

Details on exposure:

- PREPARATION OF DOSING SOLUTIONS:
A dose formulation analysis was not performed in this study as test item was administered as it is.

Analytical verification of doses or concentrations:

no

Details on analytical verification of doses or concentrations:

A dose formulation analysis was not performed in this study as test item was administered as it is.

Details on mating procedure:

- Impregnation procedure: cohoused
- If cohoused:
- M/F ratio per cage: Mating was performed using a ratio of 1:2 (male to female).
- Further matings after two unsuccessful attempts: no; after getting 100 sperm positive females, the remaining females and males were discarded without any observations.
- Proof of pregnancy: sperm in vaginal smear referred to as gestation day (GD) 0

Duration of treatment / exposure:

The female animals were treated with the test item or control item between gestation day 5 until gestation day 19.

Frequency of treatment:

daily

Duration of test:

15 days

Dose / conc.:

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

Dose / conc.:

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

Dose / conc.:

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

No. of animals per sex per dose:

25 females/group

Control animals:

yes, sham-exposed

Details on study design:

- Dose selection rationale: Doses were selected based on a dose-range finding study. The highest dose level was chosen with the aim of inducing toxic effects, but not death or severe suffering. Thereafter, a descending sequence of dose levels was selected with a view to demonstrate any dose-related response and a NOAEL.

Maternal examinations:

CAGE SIDE OBSERVATIONS: Yes
- Time schedule: at least once a day, preferably at the same time each day
- Cage side observations included: spontaneous activity, lethargy, recumbent position, convulsions, tremors, apnoea, asphyxia, vocalisation, diarrhoea, changes in the skin and fur, eyes and mucous membranes (salivation, discharge), piloerection and pupil size. Changes in gait, posture, response to handling as well as the presence of clonic or tonic movements, stereotypes, difficult or prolonged parturition or bizarre behaviour

DETAILED CLINICAL OBSERVATIONS: Yes
- Time schedule: at least once a day, preferably at the same time each day

BODY WEIGHT: Yes
- Time schedule for examinations: Mean body weights were recorded on gestation days 0, 5, 8, 11, 14, 17, and 20.

FOOD CONSUMPTION: Yes
- Food consumption for each animal determined and mean daily diet consumption calculated as g food/kg body weight/day: Yes

POST-MORTEM EXAMINATIONS: Yes
- Sacrifice on gestation day # 20
- Organs examined: The uteri were removed, weighed with the cervix, and the pregnancy status of the dams was confirmed. Uteri that appeared non-gravid were further examined by staining with 10% ammonium sulphide solution to confirm the non-pregnant status. The number of corpora lutea was counted for pregnant animals. The uterine contents were examined for embryonic or foetal deaths as well as the number of viable foetuses. The degree of resorption (late and early) was confirmed in order to help estimate the relative time of death of the conceptus. The position and number of foetuses in each uterine horn was also recorded.

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

Fetal examinations:

- External examinations: Yes: all per litter
- Soft tissue examinations: Yes: half per litter
- Skeletal examinations: Yes: half per litter
- Head examinations: Yes: Craniofacial examination of the heads of the foetuses used for the soft tissue examination of the first 20 litters per group were performed

Statistics:

A statistical assessment of the results of the body weight, food consumption was performed by comparing values of dosed with control animals using a one-way ANOVA and a post-hoc Dunnett Test. Foetal evaluation parameters like external, visceral, craniofacial and skeletal parameters were analysed using Fisher’s exact test.

Indices:

Pre-implantation loss (%); post-implantation loss (%); early, late, and total resorptions

Historical control data:

Historical control data were included for uterine data, litter weight, and external, visceral, skeletal, and cranofacial fetal findings.

Clinical signs:

effects observed, non-treatment-related

Description (incidence and severity):

Low incidences of alopecia were noted in isolated females from all dose groups including the control group (2 controls, 1 each from low- and high-dose group and 2 from the mid-dose group). There was also crust on snout and abnormal breathing observed in one each mid- and high-dose group female. Moving the bedding in one low-dose, 2 high-dose and increased salivation in 2 high-dose group females on a few treatment days were observed. Moving the bedding was a transient sign and was considered to be a local reaction to the test item rather than a systemic adverse effect. All clinical signs observed in terminally sacrificed females were incidental or non adverse in nature.

Mortality:

no mortality observed

Body weight and weight changes:

no effects observed

Food consumption and compound intake (if feeding study):

no effects observed

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

Description (incidence and severity):

No test item-related effects of toxicological relevance or statistical significance were noted for gravid uterus weight.

Gross pathological findings:

no effects observed

Neuropathological findings:

not examined

Histopathological findings: non-neoplastic:

not examined

Histopathological findings: neoplastic:

not examined

Other effects:

not examined

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

Other effects:

not examined

Dose descriptor:

NOAEL

Effect level:

>= 1 000 mg/kg bw/day (nominal)

Based on:

test mat.

Basis for effect level:

other: no treatment-related effect on body weight, food consumption, prenatal data parameters and gross pathology

Abnormalities:

no effects observed

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

Changes in postnatal survival:

no effects observed

External malformations:

no effects observed

Skeletal malformations:

effects observed, non-treatment-related

Description (incidence and severity):

The following statistically significant findings were noted in litter indicence: decreased supernumerary rib cartilage (14th) (L) and 14th full rib (L) at 100 mg/kg bw/day; and increased hindlimb phalanges ossification at 100 and 1000 mg/kg bw/day. These changes were considered to be incidental as frequencies were even less in numbers compared to the controls. Therefore, these findings are not to be considered as treatment-related and solely spontaneous in nature.

In the high-dose group, slightly higher litter incidences, but without achieving statistical significance were noted for: incomplete ossification of frontal (B) (25% compared to 15% in controls), interparietal (85% compared to 65% in controls), parietal (B) (55% compared to 30% in controls), squamosal (B and R) (15-25% compared to 0-5% in controls), zygomatic arch (B) (15% compared to 5% in controls), femur (B) (15% compared to 5% in controls), basioccipital with small hole (15% compared to 5% in controls), scapula bent (B) (5% compared to 0% in control), scapula bent (R) (20% compared to 0% in control), branched xiphoid cartilage (65% compared to 55% in control), left 14th rudimentary rib (65% compared to 50% in control), wavy ribs (65% compared to 55% in controls), rudimentary 7th cervical rib (5-15% compared to 0% in control) misshapen humerus (20% compared to 5% in controls), unossified forelimb metacarpals (55% compared to 30% in controls) and pelvic girdle (B) caudal shift (20% compared to 10% in control).

The observed reduced ossification without achieving statistical significance of few bones at 1000 mg/kg bw/day that normally exhibit rapid ossification during the last days of gestation indicates a slight generalised skeletal delay at 1000 mg/kg bw/day. Generally slightly delayed ossification is not regarded to persist postnatally and not associated with long-term consequences on survival, general growth and development and therefore is not considered to be adverse.

Visceral malformations:

effects observed, non-treatment-related

Description (incidence and severity):

There was statistically significantly higher litter incidence of umbilical artery transposed in low- and high-dose groups when compared to the control group; however, values were well within historical control data range. An increased incidence either for litters and/or for individuals were observed for a few of the visceral findings including renal pelvis dilated (R) at the high dose, ureter (L) convoluted at all doses, and ureter (B) dilated at the low and high dose; these increases occurred at high numbers but did not achieve statistical significance when compared to controls and were within historical control data range (renal pelvis dilated (R)- 47.37%, ureter (L) convoluted- 73.91%, ureter (B) dilated- 87.50%). There was discolouration of organs like liver and adrenal gland observed in few foetuses of treatment and control group without dose dependency. Discolouration of organs was considered likely to reflect the consequence of a functional disorder and thus not strictly as developmental anomalies. Due to lack of dose dependency and consistency, these discolouration findings were not considered as toxicologically relevant.

Other effects:

effects observed, non-treatment-related

Description (incidence and severity):

Craniofacial examination by razor blade serial sectioning technique revealed few predominant findings (subcutaneous edema of head, retinal fold, slightly dilated 3rd ventricle and dilated lateral ventricle) at low frequencies generally comparable to or in some cases slightly higher or lower in frequency in the dose groups compared to the controls. These findings were considered to be spontaneous in nature and not related to the treatment with the test item.

Dose descriptor:

NOAEL

Effect level:

>= 1 000 mg/kg bw/day (nominal)

Based on:

test mat.

Sex:

male/female

Basis for effect level:

other: no treatment-related and toxicologically relevant effect on litter weight data, external, skeletal, visceral or craniofacial foetal findings

Abnormalities:

no effects observed

Developmental effects observed:

no

Conclusions:

In an OECD 414 study conducted in compliance with GLP, no effects of ureidopropyltrialkoxysilane on females were found at dose levels up to 1000 mg/kg body weight/day. Regarding developmental toxicity no adverse effects were observed in foetuses up to the highest dose tested. The NOAEL for maternal toxicity and embryo-foetal toxicity of ureidopropyltrialkoxysilane in this study is considered to be 1000 mg/kg body weight/day.

Effect on developmental toxicity: via oral route

Endpoint conclusion:

no adverse effect observed

Dose descriptor:

NOAEL

1 000 mg/kg bw/day

Study duration:

subacute

Species:

rat

Quality of whole database:

The study was conducted according to an appropriate OECD test guideline and in compliance with GLP.

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

In an OECD 414 study conducted in accordance to GLP, nulliparous and non-pregnant females were mated with males (2:1 ratio) and divided into four groups based on their body weights on the day of sperm positive vaginal smears (GD 0) (Eurofins, 2018). Female rats were then administered the test material via gavage during gestation days 5 to 19. The 4 groups (0, 100, 300, or 1000 mg/kg bw/day) were comprised 25 femaleWistar rats.

 

In dams, no mortality occurred during the treatment period of this study and all animals survived until terminal sacrifice. Additionally, there were no clinical signs of toxicological relevance observed in any of the treatment groups. The mean body weight remained unaffected and increased during the progress of the study in all treatment groups. There was no effect on body weight gain (gestation day 0-20) observed in any of the treatment groups when compared to the controls. No test item-related effects of toxicological relevance or statistical significance were noted for any of prenatal data parameters like terminal body weight, gravid uterus weight, adjusted maternal weights, number of corpora lutea, implantation sites, live foetuses, early and late resorptions, number of male and female foetuses, sex ratio, number of foetuses in each uterine horn and percent pre- and post-implantation loss. No dead foetuses were noted in any of the groups. Successful mating resulted in 24/25 pregnancies in the mid- and high-dose groups compared to 25/25 pregnancies in the control and low-dose group. No gross pathological changes of toxicological relevance were observed during the macroscopic examination of the treated females.

There were no test item-related effects of toxicological relevance or statistical significance observed for any litter data parameters like mean foetus weight (individual and litter basis), male and female foetus weight (individual basis), the total, male and female litter weight (litter basis) in any of the treatment groups when compared with the controls. All group mean values and individual values for various litter data parameters from treatment groups were comparable with the controls.

There were no external, visceral, or craniofacial abnormalities considered to be of toxicological relevance in any of the dose groups. Statistical analysis of data revealed no significant differences compared to the control group.

At the high dose, slightly higher litter incidences, but without achieving statistical significance were noted for: incomplete ossification of frontal (B) (25% compared to 15% in controls), interparietal (85% compared to 65% in controls), parietal (B) (55% compared to 30% in controls), squamosal (B and R) (15-25% compared to 0-5% in controls), zygomatic arch (B) (15% compared to 5% in controls), femur (B) (15% compared to 5% in controls), basioccipital with small hole (15% compared to 5% in controls), scapula bent (B) (5% compared to 0% in control), scapula bent (R) (20% compared to 0% in control), branched xiphoid cartilage (65% compared to 55% in control), left 14th rudimentary rib (65% compared to 50% in control), wavy ribs (65% compared to 55% in controls), rudimentary 7th cervical rib (5-15% compared to 0% in control) misshapen humerus (20% compared to 5% in controls), unossified forelimb metacarpals (55% compared to 30% in controls) and pelvic girdle (B) caudal shift (20% compared to 10% in control). The observed reduced ossification without achieving statistical significance of few bones at 1000 mg/kg bw/day that normally exhibit rapid ossification during the last days of gestation indicates a slight generalised skeletal delay at 1000 mg/kg bw/day. Generally slightly delayed ossification is not regarded to persist postnatally and not associated with long-term consequences on survival, general growth and development and therefore is not considered to be adverse.

 

No effects of ureidopropyltrialkoxysilane on females and foetuses were found at dose levels up to 1000 mg/kg body weight/day. The NOAEL for maternal toxicity and embryo-foetal toxicity of ureidopropyltrialkoxysilane in this study is considered to be 1000 mg/kg body weight/day.

Justification for classification or non-classification

The available data is reliable and suitable for classification. Based on this data, classification for developmental toxicity according to 67/584/EEC and EC/1272/2008 is not warranted.