3-(diethoxymethylsilyl)propylamine

Toxicity to reproduction

Administrative data

Endpoint:

toxicity to reproduction

Remarks:

other: OECD 408 (repeated dose 90-day oral toxicity in rodents)

Type of information:

migrated information: read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

key study

Study period:

1999-10-11 to 2000-03-23

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: see 'Remark'

Remarks:

The study was conducted according to an appropriate guideline, in compliance with GLP and was considered to be reliability 1 (reliable without restrictions). Read across to the registered substance is considered scientifically justified; the read across is considered to be reliability 2.

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2001

Report date:

2001

Materials and methods

Test guideline

Guideline:

other: OECD 408 (repeated dose 90-day toxicity study in rodents)

Principles of method if other than guideline:

The OECD 408 is not a reproductive toxicity guideline, but does include some elements relevant to this endpoint.

GLP compliance:

yes

Limit test:

no

Test material

Test material information

Constituent 1

Reference substance name:

3-aminopropyltriethoxysilane

EC Number:

213-048-4

EC Name:

3-aminopropyltriethoxysilane

Cas Number:

919-30-2

IUPAC Name:

3-(triethoxysilyl)propan-1-amine

Test animals

Species:

rat

Strain:

other: Crl:CD (SD) IGS BR

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Charles River Labs, Raleigh, NC, USA
- Age at study initiation: 7 wk
- Weight at study initiation: 213 g (m), 150-207 g (f)
- Housing: 1/suspended wire mesh cage
- Diet: standard diet ad libitum
- Water: drinking water ad libitum
- Acclimation period: 13 days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 70.2-73.3 deg F
- Humidity (%): 35.2-58.5
- Photoperiod (hrs dark / hrs light): 12 h/12 h

IN-LIFE DATES: From: 1999-10-11 To: 2000-01-11

Administration / exposure

Route of administration:

oral: gavage

Vehicle:

peanut oil

Details on exposure:

PREPARATION OF DOSING SOLUTIONS: vehicle dispensed daily; mixed with magnetic stirrer

VEHICLE
- Justification for use and choice of vehicle (if other than water): peanut oil sparged with nitrogen
- Concentration in vehicle:
- Amount of vehicle (if gavage):
- Lot/batch no. (if required): NQ0052 and NG0346
- Purity:

Details on mating procedure:

unmated

Analytical verification of doses or concentrations:

no

Duration of treatment / exposure:

Exposure period: 91 or 92 days

Frequency of treatment:

daily

Details on study schedule:

Unmated. Examination of reproductive organs, sperm viability and oestus cycle.

At the time of necropsy tissues and organs including the following were collected and preserved:
-mammary gland, ovaries with oviducts
-testis with epididymis and vas deferens

The right testis/epididymis from all males at the scheduled necropsy and both testes/epididymides from those males found dead were preserved in Bouin's solution and prepared for microscopic examination using PAS/hematoxylin staining. The left testis/epididymis from all males euthanized at the scheduled necropsy were prepared for sperm analysis as described below.

The organs weighed included: epididymides (weighed separately; total and cauda), ovaries (with oviducts), prostate, seminal vesicles with coagulating glands (with accessory fluids), testes (weighed separately).

Doses / concentrations

Remarks:

Doses / Concentrations:
0, 70, 200 and 600 mg/kg bw/day
Basis:
nominal conc.

No. of animals per sex per dose:

15

Control animals:

yes, concurrent vehicle

Details on study design:

- Dose selection rationale: prior 2-wk range finding test.

Positive control:

None

Examinations

Parental animals: Observations and examinations:

CAGE SIDE OBSERVATIONS: Yes
- Time schedule: twice daily

DETAILED CLINICAL OBSERVATIONS: Yes
- Time schedule: twice daily

BODY WEIGHT: Yes
- Time schedule for examinations: weekly

FOOD CONSUMPTION AND COMPOUND INTAKE (if feeding study):
Food intake was calculated as g/animal/day for the corresponding body weight intervals. When food consumption could not be measured for a given interval (due to spillage, weighing error, etc.), the appropriate interval was footnoted as "NA" (Not Applicable) on the individual tables.

Oestrous cyclicity (parental animals):

(From SIAR, 2003)
Vaginal smears for determination of the stage of estrus were obtained from all surviving females once daily beginning 21 days prior to the scheduled necropsy. The average cycle length was calculated for complete estrous cycles (i.e., the total number of returns to metestrus [M] or diestrus [D] from estrus [E] or proestrus [P]) beginning 21 days prior to the scheduled necropsy. The final vaginal smear for each female was collected on the day of necropsy.

Sperm parameters (parental animals):

(From SIAR, 2003)
Parameters examined in males: testis weight, epididymis weight, sperm count in testes, sperm count in epididymides, sperm motility, sperm morphology

PAS/hematoxylin-stained sections of the right testis and epididymis from all males were examined microscopically at the scheduled necropsy. Spermatogenic analysis was conducted according to the following protocol. For motility/viability assessment, immediately following euthanasia, the reproductive tract of each male was exposed via a ventral mid-line incision. The right epididymis was excised and weighed separately. An incision was made in the distal region of the cauda epididymis. The cauda was then placed in Dulbecco's phosphate-buffered saline (maintained at approximately 37oC) with 10 mg/ml Bovine Serum Albumin (BSA). A sample of the diluted sperm was then loaded into a 100 µm cannula for determination of motility. As sperm motility can be affected by temperature shock, all cannulas, diluents and slides were pre-warmed and maintained at approximately 37oC. Motility eterminations were performed under constant temperature using the Hamilton-Thorne HTM-IVOS Version 10 computer-assisted sperm analysis (CASA) system. At least 200 (if possible) motile and nonmotile spermatozoa/animal were analyzed. A sample of sperm for morphology assessment was obtained from the right cauda epididymis of each male. Sperm morphology was evaluated using a modification of the wet-mount technique described by Linder et al., 1992. Abnormal forms of sperm (double heads, double tails, micro- or megacephalic, etc.) were recorded from a differential count of 200 spermatozoa/animal. For enumeration of epididymal and testicular sperm numbers and sperm production rates, the left testis and epididymis from each male at the scheduled necropsy were weighed and frozen, then homogenized and evaluated for sperm production rate using the method described by Blazak et al., 1985. Analyses were performed using the Hamilton-Thorne CASA system.

Litter observations:

No litters, not applicable.

Postmortem examinations (parental animals):

(from SIAR, 2003)
SACRIFICE
- Male animals: All surviving animals at study completion (92 days)
- Female animals: All surviving animals at study completion (92 days)

GROSS NECROPSY
A complete necropsy was conducted on all animals. The necropsy included, but was not limited to, examination of the external surface, all orifices and the cranial, abdominal and pelvic cavities and their viscera.

HISTOPATHOLOGY / ORGAN WEIGHTS
At the time of necropsy, the following tissues and organs were collected and preserved in 10% neutral buffered formalin: adrenals (2), aorta, bone with marrow (femur, sternebrae), bone marrow smear (from femur), brain (forebrain, midbrain, hindbrain), coagulating gland, eyes with optic nerve (2; preserved in Davidson's solution), gastrointestinal tract (esophagus, stomach, duodenum, jejunum, ileum, cecum, colon, rectum), heart, kidneys (2), liver (sections of two lobes), lungs (including bronchi, fixed by inflation with fixation), lymph node (mesenteric, submandibular), mammary gland (females only), ovaries with oviducts (2), pancreas, peripheral nerve (sciatic), pituitary, prostate, salivary glands (submaxillary, 2), seminal vesicles (2), skeletal muscle (vastus medialis), skin, spinal cord (cervical, midthoracic, lumbar), spleen, testis with epididymis (1) and vas deferens, thymus, thyroid (with parathyroids if present (2)), trachea, urinary bladder, uterus with vagina and cervix, and all gross lesions (when possible). Bone marrow smears were obtained from all animals not found dead, but were not placed in 10% neutral buffered formalin. The right testis/epididymis from all males at the scheduled necropsy and both testes/epididymides from those males found dead were preserved in Bouin's solution and prepared for microscopic examination using PAS/hematoxylin staining. The left testis/epididymis from all males euthanized at the scheduled necropsy were prepared for sperm analysis as described below. The following organs from animals euthanized at the scheduled necropsy were weighed: adrenals, brain, epididymides (weighed separately; total and cauda), kidneys, liver, ovaries (with oviducts), pituitary, prostate, seminal vesicles with coagulating glands (with accessory fluids), testes (weighed separately), and thyroid (fixed weight). Organ to final body weight and organ to brain weight ratios were calculated. The tissues noted above from all animals found dead or euthanized in extremis and from all animals in the control and 600 mg/kg/day groups euthanized at the scheduled necropsy, as well as the lungs, liver, and kidneys from all animals in the 70 and 200 mg/kg/day groups were examined microscopically.

[See also examination of testes described above.]

Postmortem examinations (offspring):

None, no offspring.

Statistics:

(From SIAR, 2003)
All analyses were conducted using two-tailed tests for minimum significance levels of 1% and 5% comparing the test article-treated groups to the control group by sex. All means were presented with standard deviations (S.D.) and the number of sampling units (N) used to calculate the means. Statistical analyses were not conducted if the number of animals was two or less. All statistical tests were performed using appropriate computing devices or programs. Body weight, body weight change, food consumption, clinical pathology, absolute and relative organ weight data and epididymal and testicular sperm numbers and sperm production rates were subjected to a one-way analysis of variance (ANOVA), followed by Dunnett's test if the ANOVA revealed statistical significance (p<0.05). The percentage of motile spermatozoa and the percentage of sperm with normal morphology were analyzed by the Kruskal-Wallis nonparametric ANOVA test to determine intergrouup differences, followed by the Mann-Whitney U-Test comparing the control and test article-treated groups if the ANOVA revealed statistical significance (p<0.05). Clinical laboratory values for leukocytes that occur at a low incidence (i.e., monocytes, eosinophils and basophils) were not subjected to statistical analysis.

Reproductive indices:

None.

Offspring viability indices:

None.

Results and discussion

Results: P0 (first parental generation)

General toxicity (P0)

Clinical signs:

effects observed, treatment-related

Body weight and weight changes:

no effects observed

Food consumption and compound intake (if feeding study):

no effects observed

Organ weight findings including organ / body weight ratios:

effects observed, treatment-related

Histopathological findings: non-neoplastic:

effects observed, treatment-related

Reproductive function / performance (P0)

Reproductive function: oestrous cycle:

no effects observed

Reproductive function: sperm measures:

no effects observed

Reproductive performance:

not examined

Details on results (P0)

CLINICAL SIGNS AND MORTALITY (PARENTAL ANIMALS)
Deaths of 1 male and 8 females at the top dose (600 mg/kg bw/day) were believed treatment-related. These animals had laboured breathing/gasping, partially closed eyes, pallor, hypothermia, dermal atonia and/or tremor. The predominant clinical sign in surviving animals was rales (rattling/crackling sound during breathing) in the high dose group. Also at this dose, wet and/or dried material on various parts of the body and abnormal excreta were observed. These signs were observed sporadically at lower doses. (The deaths of one control male, one 200 mg/kg bw/day female and two 600 mg/kg bw/day males were due to dosing error or not considered treatment-related.)

BODY WEIGHT, WEIGHT GAIN AND FOOD CONSUMPTION; OPHTHALMOSCOPIC EXAMINATION AND HAEMATOLOGY
No clear treatment-related effects were reported on: body weight gain, food consumption, oculopathy, haematology parameters, oestrous cycle data or spermatogenic endpoints

REPRODUCTIVE FUNCTION: ESTROUS CYCLE (PARENTAL ANIMALS): no treatment-related effect


REPRODUCTIVE FUNCTION: SPERM MEASURES (PARENTAL ANIMALS): no treatment-related effect


REPRODUCTIVE PERFORMANCE (PARENTAL ANIMALS): not evaluated


ORGAN WEIGHTS (PARENTAL ANIMALS)
Increased liver weights in high dose males (non statistically significant increase in mean liver:brain weight; statistically significant increase in liver:body weight compared to controls) correlated with increased ALT and AST and hepatocellular vacuolation evident on microscopic examination. Increased adrenal weight (absolute, adrenal:brain, adrenal:body weight) in 600 mg/kg bw/day males was not associated with macroscopic, microscopic, haematologic or clinical chemistry findings, and was considered spurious.

GROSS PATHOLOGY (PARENTAL ANIMALS)
For one male and most females that died prior to scheduled necropsy, macroscopic changes included distension of various parts of the gut. The only macroscopic change at scheduled necropsy was an increased incidence of gaseous distension of the gut, primarily of the cecum, in 7/12 males and 2/7 females in the high dose group.

HISTOPATHOLOGY (PARENTAL ANIMALS)
Microscopic examination revealed changes to the liver of 600 mg/kg bw/day males consisting of centrilobular to generalized hepatocellular vacuolation. No other test article-related microscopic changes were observed.

Effect levels (P0)

1

Dose descriptor:

NOAEL

Remarks:

systemic

Effect level:

200 mg/kg bw/day

Sex:

male/female

Basis for effect level:

other: No effect on: mortality, clinical signs, liver effects

2

Dose descriptor:

NOAEL

Remarks:

reproductive

Effect level:

600 mg/kg bw/day

Sex:

male/female

Basis for effect level:

other: no effect on: reproductive organs, oestrus cycle or sperm paramenters

3

Dose descriptor:

LOAEL

Remarks:

systemic

Effect level:

600 mg/kg bw/day

Sex:

male/female

Basis for effect level:

other: mortality, clinical signs, liver effects

Results: F1 generation

General toxicity (F1)

Clinical signs:

not examined

Mortality / viability:

not examined

Body weight and weight changes:

not examined

Sexual maturation:

not examined

Organ weight findings including organ / body weight ratios:

not examined

Gross pathological findings:

not examined

Histopathological findings:

not examined

Details on results (F1)

No offspring, not applicable.

Overall reproductive toxicity

Reproductive effects observed:

not specified

Any other information on results incl. tables

A 90-day oral (gavage) toxicity study found no effect on oestrous cycle data or spermatogenic endpoints. No other test article-related microscopic changes on the reproductive organ were observed. The NOAEL for reproductive endpoints, in this limited study of reproductive toxicity, is 600 mg/kg bw/day. The NOAEL for systemic toxicity is 200 mg/kg bw/day.

[Full details of findings of this repeat dose study are given in the Endpoint study record: Repeated dose toxicity: oral 7.5.150 Momentive.]

Applicant's summary and conclusion

Conclusions:

A well reported repeated dose 90-day oral toxicity study, conducted in the main according to the current guideline for that endpoint and in accordance with GLP, identified a systemic NOAEL value of 200 mg/kg bw/day in male and female rats; mortality, clinical observations and liver effects were evident at 600 mg/kg bw/day. No effects on reproductive organs, oestrus cycle or sperm parameters were evident at the highest tested dose of 600 mg/kg bw/day. This study would have only limited potential to detect all possible reproductive effects.