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Toxicological information

Repeated dose toxicity: oral

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Administrative data

Endpoint:
sub-chronic toxicity: oral
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2018

Materials and methods

Test guideline
Qualifier:
according to guideline
Guideline:
OECD Guideline 408 (Repeated Dose 90-Day Oral Toxicity Study in Rodents)
Version / remarks:
21 September 1998
Deviations:
no
GLP compliance:
yes (incl. QA statement)
Remarks:
Bayerisches Landesamt für Gesundheit und Lebensmittelsicherheit
Limit test:
no

Test material

Constituent 1
Chemical structure
Reference substance name:
-
EC Number:
449-160-7
EC Name:
-
Cas Number:
116912-64-2
Molecular formula:
C7H18N2O4Si C8H20N2O4Si C9H22N2O4Si C10H24N2O4Si
IUPAC Name:
[3-(ethoxydimethoxysilyl)propyl]urea; [3-(trimethoxysilyl)propyl]urea; {3-[diethoxy(methoxy)silyl]propyl}urea

Test animals

Species:
rat
Strain:
Wistar
Details on species / strain selection:
Crl: WI(Han) (Full Barrier)
Sex:
male/female
Details on test animals or test system and environmental conditions:
TEST ANIMALS
- Source: Charles River, 97633 Sulzfeld, Germany
- Females nulliparous and non-pregnant: yes
- Age at study initiation: 6-7 weeks old (main study)
- Weight at study initiation: main study: males: 152 – 184 g; females: 118 – 147 g
- Housing: The animals were kept in groups of up to 5 animals / sex / group / cage in cages (type IV, polysulphone cages) on Altromin saw fibre bedding.
- 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 x / hour
- Photoperiod (hrs dark / hrs light): artificial light, sequence being 12 hours light, 12 hours dark

Administration / exposure

Route of administration:
oral: gavage
Details on route of administration:
The test item or control item was administered at a single dose to the animals by oral gavage. The dose volume was 1 (sterile water) mL/kg bw for control animals, 0.091 mL/kg bw for low-dose animals, 0.27 mL/kg bw for mid-dose animals, and 0.91 mL/kg bw for high-dose animals.
Vehicle:
unchanged (no vehicle)
Details on oral 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.
Duration of treatment / exposure:
90 days
Frequency of treatment:
daily
Doses / concentrationsopen allclose all
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:
10 animals/sex/group for the 4 treatment groups; 5 animals/sex/group for the recovery group which consisted for the control and high group
Control animals:
yes, sham-exposed
Details on study design:
- Dose selection rationale: Doses were based on a dose-range finding study
- Rationale for animal assignment: Before the first administration all animals used for the study were weighed and assigned to the experimental groups with achieving a most homogenous variation in body weight throughout the groups of males and females, respectively (randomisation was performed with IDBS Workbook 10.1.2 software).
Positive control:
No

Examinations

Observations and examinations performed and frequency:
CAGE SIDE OBSERVATIONS: Yes
- Time schedule: Cage side observations were made outside the home cage in a standard arena once before the first administration and at least once a week thereafter.
- Cage side observations included: spontaneous activity, lethargy, recumbent position, convulsions, tremors, apnoea, asphyxia, vocalisation, diarrhoea, changes in skin and fur, eyes and mucous membranes (salivation, discharge), piloerection and pupil size

DETAILED CLINICAL OBSERVATIONS: Yes
- Time schedule: at least once a day, preferably at the same time each day and considering the peak period of anticipated effects after dosing

BODY WEIGHT: Yes
- Time schedule for examinations: The body weight was recorded once before the assignment to the experimental groups, on the first day of administration and weekly thereafter.

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

OPHTHALMOSCOPIC EXAMINATION: Yes
- Time schedule for examinations: Ophthalmological examinations, using an ophthalmoscope were made on all animals of the main study before the first administration and in the last week of the treatment period as well as at the end of the recovery period in the recovery animals.

HAEMATOLOGY: Yes
- Time schedule for collection of blood: at the end of the treatment and recovery period prior to or as part of the sacrifice of the animals
- Anaesthetic used for blood collection: Not specified
- Animals fasted: Yes
- How many animals: all
- Parameters checked in tables 1 and 2 were examined.

CLINICAL CHEMISTRY: Yes
- Time schedule for collection of blood: at the end of the treatment and recovery period prior to or as part of the sacrifice of the animals
- Animals fasted: Yes
- How many animals: all
- Parameters checked in table 3 were examined.

URINALYSIS: Yes
- Time schedule for collection of urine: prior to or as part of the sacrifice
- Metabolism cages used for collection of urine: No
- Animals fasted: Yes
- Parameters checked in table 4 were examined.

NEUROBEHAVIOURAL EXAMINATION: Yes
- Time schedule for examinations: once before the first exposure and once in the last week of exposure as well as in the last week of the recovery period
- Dose groups that were examined: all dose groups
- Battery of functions tested: sensory activity / grip strength / motor activity / other: Sensory reactivity to different modalities, grip strength and motor activity assessments and other behavioural observations as well as rearing supported and not supported, urination, defecation, startle/ auditory response, equilibrium reflex, positional passivity, visual placing, fore and hind limb grip strength, tail pinch response, toe pinch reflex, extensor thrust/limb tone, hind limb reflex, righting reflex on the ground, air righting reflex, pupil response, body temperature and ophthalmoscopy (anterior chamber of the eye and fundus of eye).

IMMUNOLOGY: No

OTHER: Examination of fertility parameters was conducted in all animals of the main study.

Daily over a period of 8 days, the estrous cycle of all female animals were examined 4, 8 and 12 weeks after the first administration. In the recovery animals the estrous cycle was also examined during the last week of the recovery period.

At necropsy (one day after the last administration) and at the end of the recovery period, left epididymis, left testis and left vas deferens were separated and used for evaluation of sperm parameters.

Epididymal sperm motility and testicular sperm count were evaluated in all male animals. Sperm morphology slides were prepared from all male animals (main and recovery).
Sacrifice and pathology:
GROSS PATHOLOGY: Yes (see tables 5 and 6)

HISTOPATHOLOGY: Yes (see table 6)
Statistics:
A statistical assessment of the results of the body weight, food consumption, parameters of haematology, blood coagulation and clinical biochemistry and absolute and relative organ weights and sperm analysis were performed for each gender by comparing values of dosed with control animals using either a parametric one-way ANOVA and a post-hoc Dunnett Test or a non-parametric Kruskal-Wallis Test and a post-hoc Dunn’s Test, based on the results of homogeneity and normality tests. Furthermore, statistical comparisons of data acquired during the recovery period or comparison of the control groups were performed with a Student’s t-Test or Mann-Whitney U-Test when appropriate. P<0.05 is considered as statistically significant.

Statistical assessment was only performed with the results of the main study.

Results and discussion

Results of examinations

Clinical signs:
effects observed, non-treatment-related
Description (incidence and severity):
During the treatment period, slight to moderate salivation was noted on few days in all males (main group), 3 high-dose females (main) and one high-dose recovery male. Furthermore, moving the bedding was observed transitorily in all males (main and recovery and 5 females of the main and one female of recovery group. As the symptoms of salivation and moving the bedding were noted mainly immediately after administration, these signs were considered to be a sign of a local reaction to the test item rather than a systemic effect of the test item. No clinical signs were observed in any of the recovery animals during the recovery period except for alopecia on various body parts in one high-dose recovery female from day 47 to 118.

Low incidences of slight clinical signs like alopecia on various body parts, tremor and chromodacryorrhea were noted in isolated females of the dose groups, as well as control group during the treatment and recovery periods. These effects are considered to be incidental.
Mortality:
no mortality observed
Body weight and weight changes:
effects observed, non-treatment-related
Description (incidence and severity):
Differences in body weight development were marginal and values were within the normal range of variation for animals of this strain. Therefore, these effects on body weight and body weight gain were not considered as adverse effect of the test item and to have no toxicological significance.
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:
no effects observed
Haematological findings:
effects observed, non-treatment-related
Description (incidence and severity):
In males sacrificed at the end of treatment period, there was a statistically significant increase in mean corpuscular haemoglobin concentration (MCHC) at the high-dose group, eosinophil numbers at the low-dose group and monocyte numbers at the mid-dose group when compared with the controls. In males sacrificed at the end of recovery period, no statistically significant effects were observed on any of the haematology parameter when compared with the recovery controls.

In females sacrificed at the end of treatment period, no statistically significant effect was observed on any haematology parameter when compared with the recovery controls. In females sacrificed at the end of the recovery period, a marginal but statistically significant lower mean value of mean corpuscular volume (MCV) and a higher value of mean corpuscular haemoglobin concentration (MCHC) in the high-dose group were observed when compared with the controls. As the respective haematology values were within the normal range of variation for animals of this strain and age, differences are not assumed to be biologically relevant although statistically significant.

All other haematological parameters and blood coagulation parameters in males and females sacrificed at the end of treatment and recovery period were in the normal range of variation and no statistical significance or test item-related effects were observed.
Clinical biochemistry findings:
effects observed, non-treatment-related
Description (incidence and severity):
In males sacrificed at the end of treatment period, statistical analysis of clinical biochemistry data revealed statistically significant higher total bile acids group mean values in the mid-dose group when compared with the controls. In males sacrificed at the end of the recovery period, no statistically significant effect was observed on any of the clinical biochemistry parameter when compared with the controls.

In females sacrificed at the end of the treatment period, statistically significant lower cholesterol was observed in the low-dose and mid-dose groups when compared with the controls. In females sacrificed at the end of the recovery period, statistically significant lower group mean values for aspartate-aminotransferase was observed in the high-dose recovery group when compared with the recovery controls.

As the respective clinical biochemistry values were either within the normal range of variation for animals of this strain and age, lacked dose dependency or such effect was not observed at the end of treatment period, these differences are not assumed to be biologically relevant although statistically significant.
All other clinical biochemistry parameters in males and females sacrificed at the end of treatment and recovery period were in the normal range of variation and no statistical significance or test item-related effects were observed.
Urinalysis findings:
effects observed, non-treatment-related
Description (incidence and severity):
Slightly higher leukocyte and protein levels were found in the urine of the majority of male animals and in a few females from all the groups including controls at the end of the treatment period and end of the recovery period and thus considered not treatment-related.
Behaviour (functional findings):
effects observed, non-treatment-related
Description (incidence and severity):
In last week of treatment (week 13), there were statistically significant higher group mean scores for response to handling and finger approach and lower scores for head touch and urination in high-dose males when compared with the controls. No effect was observed in the main female treatment groups. In high-dose recovery males (week 13), statistically significantly higher group mean scores for fear and head touch were observed. In high-dose recovery females (week 13), a statistically significant lower group mean score for animal sleeps and a higher score for animal moving in the cage was observed. Due to a lack of consistency, no toxicological significance can be attributed to these few findings. There were no biologically relevant differences in body temperature between the main and recovery groups of males and females.
Immunological findings:
not examined
Organ weight findings including organ / body weight ratios:
effects observed, non-treatment-related
Description (incidence and severity):
No statistically significant effect on organs weights was observed in male and females sacrificed at the end of treatment period. There was statistically significant lower relative (to body weight) epididymides weights in high-dose recovery males, higher brain weights and lower relative (to body weight) heart weights in high-dose recovery females observed when compared with respective control group. This effect on organ weights in high-dose male and female 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.
Gross pathological findings:
no effects observed
Description (incidence and severity):
Gross lesions were unremarkable and not related to treatment with the test item.
Neuropathological findings:
not examined
Histopathological findings: non-neoplastic:
no effects observed
Description (incidence and severity):
From the microscopic findings recorded, no histological lesion, distinguished controls from test item-treated animals.
Histopathological findings: neoplastic:
not examined
Other effects:
no effects observed
Description (incidence and severity):
There was not any change at all noted in reproductive organs.

Effect levels

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 test item related effect observed on mortality, clinical signs, body weight, food consumption, functional observation battery, clinical observations, haematology, clinical biochemistry, urinalysis, gross pathology, organ weight and histopathology.

Target system / organ toxicity

Critical effects observed:
no

Applicant's summary and conclusion

Conclusions:
On the basis of the present study, the 90-Day Repeated Dose Oral Toxicity study with Ureidopropyltrialkoxysilane in male and female Wistar rats, with dose levels of 100, 300 and 1000 mg/kg body weight/day, no major toxicity or mortality was revealed.

There was no test item related effect observed on mortality, clinical signs, body weight development, food consumption, functional observation battery, weekly detailed clinical observations, haematology and blood coagulations, clinical biochemistry, urinalysis, gross pathological findings, organ weight and histopathology up to a dose of 1000 mg/kg body weight. No effects of ureidopropyltrialkoxysilane were found at the dose level of 1000 mg/kg bw/day. Therefore, the NOAEL of ureidopropyltrialkoxysilane in this study is considered to be 1000 mg/kg bw/day.