N-(3-(trimethoxysilyl)propyl)ethylenediamine

Developmental toxicity / teratogenicity

Administrative data

Endpoint:

developmental toxicity

Type of information:

experimental study

Adequacy of study:

key study

Study period:

22 February 2016 - 02 May 2016

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2016

Report date:

2016

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 414 (Prenatal Developmental Toxicity Study)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Limit test:

no

Test material

Test material information

Constituent 1

Reference substance name:

N-(3-(trimethoxysilyl)propyl)ethylenediamine

EC Number:

217-164-6

EC Name:

N-(3-(trimethoxysilyl)propyl)ethylenediamine

Cas Number:

1760-24-3

Molecular formula:

C8H22N2O3Si

IUPAC Name:

N-(3-(trimethoxysilyl)propyl)ethylenediamine

Test material form:

liquid

Specific details on test material used for the study:

Lot no. 0008326230
Exp. date: 15-Jul-2018
CAS no. 1760-24-3
Storage: Room temperature (18°C to 24°C), purge with nitrogen

Test animals

Species:

rat

Strain:

Sprague-Dawley

Details on test animals or test system and environmental conditions:

ANIMAL SELECTION AND TEST SYSTEM
Sexually mature, virgin female Sprague Dawley [Crl:CD(SD)] rats were used as the test system on this study. This species and strain of animal is recognized as appropriate for developmental toxicity studies. This animal model has been proven to be susceptible to the effects of developmental toxicants. The number of animals selected for this study (25 females/group) was based on the Test Guidelines: OPPTS 870.3700/OECD 414, which recommend evaluation of approximately 20 females with implantation sites at necropsy. Given the possibility of nongravid animals, unexpected deaths, or treatment-related moribundity and/or mortality, this was an appropriate number of animals to obtain a sample size of 20 at termination.

ANIMAL RECEIPT, AND ACCLIMATION
Rats (125 females) were received in good health from Charles River Laboratories, Inc., Raleigh, NC, USA. The animals were approximately 79 days old upon receipt. Each female was examined on the day of receipt. The day following receipt, all animals were weighed and clinical observations were recorded. Each animal was uniquely identified using a programmable microchip (BMDS system) which was implanted subcutaneously in the dorsoscapular region during the acclimation period. The animals were housed for a minimum of 14 days for acclimation purposes. During the acclimation period, the rats were observed twice daily for mortality and changes in general appearance and behaviour.

ANIMAL HOUSING
Upon arrival, all rats were housed 2-3 per cage in clean, solid-bottom cages with bedding material (Bed-O'Cobs®; The Andersons, Cob Products Division, Maumee, OH). The rats were paired for mating in the home cage of the male. Following positive evidence of mating, the females were individually housed in clean, solid-bottom cages with bedding material. Animals were maintained in accordance with the Guide for the Care and Use of Laboratory Animals (National Research Council, 2011). Enrichment devices were provided to all animals as appropriate throughout the study for environmental enrichment and to aid in maintaining the animals’ oral health, and were sanitised weekly.

DIET, DRINKING WATER, AND MAINTENANCE
The basal diet used in this study, PMI Nutrition International, LLC Certified Rodent LabDiet® 5002. Feed lots used during the study were documented in the study records. The feeders were changed and sanitised once per week. Municipal water supplying the facility was sampled for contaminants according to the Lab SOPs. The results of the diet and water analyses are maintained at WIL Research. No contaminants were present in animal feed or water at concentrations sufficient to interfere with the objectives of this study. Reverse osmosis-purified (on-site) drinking water, delivered by an automatic watering system, and the basal diet were provided ad libitum throughout the acclimation period and during the study.

ENVIRONMENTAL CONDITIONS
All rats were housed throughout the acclimation period and during the study in an environmentally controlled room. The room temperature and relative humidity controls were set to maintain environmental conditions of 22°C ± 3°C and 50% ± 20%, respectively. Room temperature and relative humidity data were monitored continuously and were scheduled for automatic collection on an hourly basis. Fluorescent lighting provided illumination for a 12-hour light (0600 hours to 1800 hours)/12-hour dark photoperiod. The light status (on or off) was recorded once every 15 minutes. Air handling units were set to provide a minimum of 10 fresh air changes per hour.

Administration / exposure

Route of administration:

oral: gavage

Vehicle:

corn oil

Remarks:

(dried and deacidified corn oil, prepared using corn oil).

Details on exposure:

The vehicle and test substance formulations were administered orally by gavage, via an appropriately sized flexible, disposable plastic feeding tube (Instech Solomon, Plymouth Meeting, PA, USA), once daily during gestation days 6-19. The dose volume for all groups was 2 mL/kg. Individual dosages were based on the most recently recorded body weights to provide the correct mg/kg/day dose. All animals were dosed at approximately the same time each day.

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

Stability of the test article in the vehicle at concentrations of 50 and 375 mg/mL was established in a previous study (Akalkotkar, A. Analytical Validation, Homogeneity, and Stability of N-(3-(trimethoxysilyl)propyl)ethylenediamine (Study No. WIL-738013). WIL Research, Ashland, OH, USA, 2016) for 2 hours of room temperature storage. Samples for homogeneity and concentration determination were collected from the top, middle, and bottom strata of the first 50 and 375 mg/mL dosing formulations and from the middle stratum of the first control and 250 mg/mL dosing formulations. Samples for concentration analysis were also collected from the middle stratum of the last dosing formulations (including the control group) prepared during the study. One set of samples from each collection was subjected to the appropriate analyses. All remaining samples were stored at room temperature as back-up.

Details on mating procedure:

At the end of the acclimation period, all available females were weighed and examined in detail for physical abnormalities. Each animal judged to be in good health and meeting acceptable body weight requirements was placed in a solid-bottom cage with bedding material with a resident male from the same strain and source for breeding. Resident males were untreated, sexually mature rats utilised exclusively for breeding. These rats were maintained under similar laboratory conditions as the females. A breeding record containing the male and female identification numbers and the dates of cohabitation was maintained. The selected females were approximately 13 weeks old when paired for breeding.

Positive evidence of mating was confirmed by the presence of a vaginal copulatory plug or the presence of sperm in a vaginal lavage and verified by a second biologist. Each mating pair was examined daily. The day on which evidence of mating was identified was termed gestation day 0 and the animals were separated. The experimental design consisted of 3 test substance-treated groups and 1 control group, composed of 25 rats per group. The bred females were assigned to groups using a WTDMS™ computer program which randomized the animals based on stratification of the gestation day 0 body weights in a block design. Replacement animals were arbitrarily assigned based on bodyweight. Animals not assigned to study were transferred to the Lab's colony. Bodyweight values ranged from 227 g to 290 g on gestation day 0.

Duration of treatment / exposure:

The vehicle and test substance formulations were administered orally by gavage during gestation days 6-19.

Frequency of treatment:

Once daily

Doses / concentrations

Doses / concentrations 1

Dose / conc.:

0 mg/kg bw/day

Remarks:

Vehicle control

Doses / concentrations 2

Dose / conc.:

100 mg/kg bw/day

Remarks:

N-(3-(trimethoxysilyl)propyl)ethylenediamine (CAS No. 1760-24-3)

Doses / concentrations 3

Dose / conc.:

500 mg/kg bw/day

Remarks:

N-(3-(trimethoxysilyl)propyl)ethylenediamine (CAS No. 1760-24-3)

Doses / concentrations 4

Dose / conc.:

750 mg/kg bw/day

Remarks:

N-(3-(trimethoxysilyl)propyl)ethylenediamine (CAS No. 1760-24-3)

No. of animals per sex per dose:

25F/dose group

Control animals:

yes, concurrent vehicle

Details on study design:

Dose levels were determined based on a previously conducted 7-day oral gavage tolerability study in non-pregnant rats at dosage levels of 750 and 1000 mg/kg bw/day (Edwards, T.E. A 7-Day Oral (Gavage) Tolerability Study of N-(3-(trimethoxysilyl)propyl)ethylenediamine in Non-Pregnant Female Sprague-Dawley Rats (WIL-738011). WIL Research, Ashland, OH, USA, 2016.). Two of 6 females in the 1000 mg/kg bw/day group were noted with a body weight loss from study days 0-7. All females in the 750 mg/kg bw/day group had an overall body weight gain for the study period with the exception of 1 female that was found dead on study day 5. It was unclear if this death was related to test substance administration because no deaths were noted at 1000 mg/kg bw/day. Therefore, a high-dose level of 750 mg/kg bw/day was selected for the current study and the low- and mid-dosage levels were selected to explore the dose-response relationship. The selected route of administration for this study was oral (gavage) because this is a potential route of exposure for humans.

Examinations

Maternal examinations:

CLINICAL OBSERVATIONS AND SURVIVAL
All rats were observed twice daily, once in the morning and once in the afternoon, for moribundity and mortality. Individual clinical observations were recorded daily from gestation days 0-20 (prior to dose administration during the treatment period). Animals were also observed for signs of toxicity approximately 1 hour following dose administration. The absence or presence of findings was recorded for all animals. In addition, the presence of findings at the time of dose administration was recorded for individual animals.

BODY WEIGHTS AND GRAVID UTERINE WEIGHTS
Individual maternal body weights were recorded on gestation days 0 and 6-20 (daily). Group mean body weights were calculated for each of these days. Mean body weight changes were calculated for each corresponding interval and also for gestation days 6-9, 9-12, 12-15, 15-20, and 6-20. Gravid uterine weight was collected and net body weight (the gestation day 20 body weight exclusive of the weight of the uterus and contents) and net body weight change (the gestation day 0-20 body weight change exclusive of the weight of the uterus and contents) were calculated and presented for each gravid female at the scheduled laparohysterectomy.

FOOD CONSUMPTION
Individual food consumption was recorded on gestation days 0 and 6-20 (daily). Food intake was reported as g/animal/day and g/kg/day for the corresponding body weight change intervals.

Ovaries and uterine content:

Laparohysterectomies and macroscopic examinations were performed blind to treatment group. All rats were euthanized on gestation day 20 by carbon dioxide inhalation. The thoracic, abdominal, and pelvic cavities were opened by a ventral mid-line incision, and the contents were examined. In all instances, the postmortem findings were correlated with the antemortem observations, and any abnormalities were recorded. The uterus and ovaries were then exposed and excised. The number of corpora lutea on each ovary was recorded. The trimmed uterus was weighed and opened, and the number and location of all fetuses, early and late resorptions, and the total number of implantation sites were recorded. The placentae were also examined. The individual uterine distribution of implantation sites was documented using the following procedure. All implantation sites, including resorptions, were numbered in consecutive order beginning with the left distal to the left proximal uterine horn, noting the position of the cervix, and continuing from the right proximal to the right distal uterine horn. Maternal tissues were preserved in 10% neutral-buffered formalin for possible future histopathologic examination only as indicated by the gross findings. Representative sections of corresponding organs from a sufficient number of control animals were retained for comparison. The carcass of each female was then discarded.

Fetal examinations:

Fetal examinations were performed blind to treatment group. Each viable fetus was examined externally, individually sexed, weighed, euthanized by a subcutaneous injection of sodium pentobarbital in the scapular region, and tagged for identification. Fetal tags contained the Lab's study number, the female number, and the fetus number. The detailed external examination of each fetus included, but was not limited to, an examination of the eyes, palate, and external orifices, and each finding was recorded. Crown-rump measurements and degrees of autolysis were recorded for late resorptions, a gross external examination was performed (if possible), and the tissues were discarded.
Approximately one-half of the viable fetuses in each litter was subjected to a visceral examination using a modification of the Stuckhardt and Poppe fresh dissection technique to include the heart and major blood vessels (Stuckhardt and Poppe, 1984). The sex of each fetus was confirmed by internal examination. Fetal kidneys were examined and graded for renal papillae development (Woo and Hoar, 1972). Heads from the fetuses examined viscerally were placed in Harrison’s fixative for subsequent soft-tissue examination by the Wilson sectioning technique (Wilson, 1965). All carcasses were eviscerated and fixed in 100% ethyl alcohol. The fetuses were stained as described below for possible skeletal examination.
The other one-half of fetuses not examined viscerally were eviscerated and fixed in 100% ethyl alcohol. Following fixation in alcohol, each fetus was stained with Alizarin Red S (Dawson, 1926) and Alcian Blue (Inouye, 1976). Fetuses were then examined for skeletal malformations and developmental variations.
External, visceral, and skeletal findings were recorded as developmental variations (alterations in anatomic structure that are considered to have no significant biological effect on animal health or body conformity and/or occur at high incidence, representing slight deviations from normal) or malformations (those structural anomalies that alter general body conformity, disrupt or interfere with normal body function, or may be incompatible with life). The fetal developmental findings were summarized by: 1) presenting the incidence of a given finding both as the number of fetuses and the number of litters available for examination in the group; and 2) considering the litter as the basic unit for comparison and calculating the number of affected fetuses in a litter on a proportional basis.

Statistics:

All statistical tests were performed using WTDMS™. Analyses were conducted using two-tailed tests for minimum significance levels of 1% and 5%, comparing each test substance-treated group to the control group. Each mean was presented with the standard deviation (S.D.), standard error (S.E.), and the number of animals (N) used to calculate the mean. Due to the use of significant figures and the different rounding conventions inherent in the types of software used, the means, standard deviations, and standard errors on the summary and individual tables may differ slightly. Therefore, the use of reported individual values to calculate subsequent parameters or means will, in some instances, yield minor variations from those listed in the report data tables. Where applicable, the litter was used as the experimental unit. Maternal body weights (absolute and net), body weight changes (absolute and net), and food consumption, gravid uterine weights, numbers of corpora lutea, implantation sites, and viable fetuses, fetal body weights (separately by sex and combined), and litter weights were subjected to a parametric one-way ANOVA to determine intergroup differences. If the ANOVA revealed significant (p<0.05) intergroup variance, Dunnett's test was used to compare the test substance-treated groups to the control group. Mean litter proportions (%/litter) of prenatal data (viable and nonviable fetuses, early and late resorptions, total resorptions, pre- & postimplantation loss, and fetal sex distribution), total fetal malformations and developmental variations (external, visceral, skeletal, and combined) and each particular external, visceral, and skeletal malformation or variation were subjected to the Kruskal-Wallis nonparametric ANOVA test to determine intergroup differences. If the nonparametric ANOVA revealed significant (p<0.05) intergroup variance, Dunn’s test (Dunn, 1964) was used to compare the test substance-treated groups to the control group.

Historical control data:

The Lab has historical control data on the background incidence of fetal malformations and developmental variations in the Crl:CD(SD) rat.

Results and discussion

Results: maternal animals

General toxicity (maternal animals)

Clinical signs:

effects observed, treatment-related

Description (incidence and severity):

The clinical signs of rales were noted in the 500 and 750 mg/kg bw/day groups at the daily examinations and approximately 1 hour following dose administration as early as gestation day 8 and generally continued to be observed through gestation day 20. Although this finding was considered test substance-related, due to the absence of any other evidence of maternal toxicity, this finding was not considered adverse. In addition, test substance-related increased incidences of clear material around the mouth were noted for the 500 and 750 mg/kg bw/day groups approximately 1 hour following dose administration during gestation days 7-19 and salivation prior to dosing was noted at 750 mg/kg bw/day during gestation days 16-18. These findings did not persist to the daily examinations on the following day and were therefore not considered to be adverse. Findings noted in the test substance-treated groups, including hair loss on the forelimbs, occurred infrequently, at similar frequencies in the control group, and/or in a manner that was not dose-related.

Mortality:

no mortality observed

Body weight and weight changes:

no effects observed

Description (incidence and severity):

Mean maternal body weights, body weight gains, net body weights and net body weight gains in the 100, 500, and 750 mg/kg bw/day groups were unaffected by test substance administration. Differences from the control group were slight and not statistically significant.

Food consumption and compound intake (if feeding study):

no effects observed

Description (incidence and severity):

Mean maternal food consumption, evaluated as g/animal/day and g/kg/day, in the 100, 500, and 750 mg/kg bw/day groups was unaffected by test substance administration. Differences from the control group were slight, not statistically significant, did not occur in a dose-related manner, and/or were transient in nature.

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):

Gravid uterine weights in the 100, 500, and 750 mg/kg bw/day groups were unaffected by test substance administration. Differences from the control group were slight and not statistically significant.

Maternal developmental toxicity

Number of abortions:

no effects observed

Description (incidence and severity):

No maternal toxicity was noted at 100, 500, or 750 mg/kg bw/day.

Pre- and post-implantation loss:

no effects observed

Effect levels (maternal animals)

Key result

Dose descriptor:

NOAEL

Effect level:

750 mg/kg bw/day

Based on:

test mat.

Basis for effect level:

other: No evidence of maternal toxicity noted.

Maternal abnormalities

Abnormalities:

no effects observed

Results (fetuses)

Fetal body weight changes:

no effects observed

Description (incidence and severity):

Mean female fetal body weights in the 100 and 500 mg/kg bw/day groups and mean combined fetal body weight in the 500 mg/kg bw/day group were significantly (p<0.05) lower than the concurrent control group values. These values were within the Lab's historical control ranges and in the absence of a dose response, these reductions were not attributed to the test substance.

Reduction in number of live offspring:

no effects observed

Description (incidence and severity):

The numbers of fetuses (litters) available for morphological evaluation were 365(25), 383(25), 377(25), and 380(25) in the control, 100, 500, and 750 mg/kg bw/day groups, respectively. Malformations were observed in 2(2), 0(0), 2(2), and 0(0) fetuses (litters) in these same respective dose groups and were considered spontaneous in origin.

External malformations:

effects observed, non-treatment-related

Description (incidence and severity):

No external developmental variations were observed in fetuses in this study.
External malformations were observed in 1 fetus each in the control and 500 mg/kg bw/day groups. In the 500 mg/kg bw/day group, external malformations noted consisted of maxillary micrognathia, anophthalmia (bilateral), amelia (hindlimbs), brachydactyly (digit no. 1, right forepaw), micromelia (right forelimb), gastroschisis (portion of liver, stomach, and several loops of intestine protruded through an opening in the ventral midline), anotia, and bent tail. Skeletally, anophthalmia consisted of orbits that were smaller than normal, a misshapen right zygomatic process of the maxilla, and small zygomatic processes of the squamosal bone and brachydactyly consisted of small proximal and distal phalanges for digit no.1 on the right forepaw. Amelia of the hindlimbs consisted skeletally of small and malformed cartilaginous templates for the femur, tibula, and fibula, absent metatarsals and phalanges, small right ilium and ischium, unossified left ilium, absent right pubis, and unossified left pubis.
Skeletally, micromelia consisted of small scapula, small and bent humerus, unossified radius and ulna, cartilaginous templates for the radius and ulna small and bent, and all metacarpals unossified. Maxillary micrognathia consisted skeletally of small premaxilla bones and small and misshapen maxilla bones. There was no apparent skeletal origin noted for anotia and bent tail.
The external malformations observed in the 500 mg/kg bw/day group were limited to a single fetus and were not observed at 750 mg/kg bw/day. Therefore, these malformations were not considered test substance-related. In the control group, fetus no. 3960-01 had maxillary micrognathia (bilateral) which skeletally consisted of small premaxilla bones.

Skeletal malformations:

effects observed, non-treatment-related

Description (incidence and severity):

Skeletal malformations were noted for a single fetus in the 500 mg/kg bw/day group that also had multiple external malformations. This fetus had a skull anomaly that consisted of an absent prespheniod bone and misshapen frontal bones in addition to misshapen phalanges (all phalanges in digit nos. 2 through 5 on the right forepaw). These skeletal malformations were observed in a single fetus and were not observed in a dose-related manner. Therefore, the skeletal malformations observed in the 500 mg/kg bw/day group were not considered test substance-related.

Visceral malformations:

effects observed, non-treatment-related

Description (incidence and severity):

Visceral malformations were observed in 1 fetus each in the control and 500 mg/kg bw/day groups. The one fetus in the 500 mg/kg bw/day group had an interrupted aortic arch (brachiocephalic trunk and left carotid artery arose from ascending aorta, left subclavian artery arose from descending aorta, ductus arteriosus communicated with descending aorta). Because this malformation was noted in a single fetus and not observed in a dose-related manner it was not attributed to maternal test substance administration. In the control group, the fetus had lobular dysgenesis of the lungs (one lobe present) and right-sided aortic arch (aortic arch and descending aorta coursed to the right of the veterbral column, right carotid and subclavian arteries arose independently from the aortic arch [no brachiocephalic trunk], left carotid and subclavian arteries arose from a common vessel from the aortic arch).

No test item-related visceral developmental variations were noted. Renal papilla(e) not fully developed (Woo and Hoar Grade 1) was observed for 1, 1, and 4 fetuses in the 100, 500, and 750 mg/kg bw/day groups, respectively. This finding was not classified as either a malformation or developmental variation, was not reported, and was not considered to be test substance-related because it occurred infrequently.

Details on embryotoxic / teratogenic effects:

No evidence of maternal or developmental toxicity was noted at 100, 500, or 750 mg/kg bw/day.

Effect levels (fetuses)

Dose descriptor:

NOAEL

Effect level:

750 mg/kg bw/day

Based on:

test mat.

Sex:

male/female

Basis for effect level:

other: No effects noted in fetuses.

Fetal abnormalities

Abnormalities:

no effects observed

Overall developmental toxicity

Developmental effects observed:

no

Lowest effective dose / conc.:

750 mg/kg bw/day

Treatment related:

no

Any other information on results incl. tables

ANALYSES OF DOSING FORMULATIONS

Analyses of Dosing Formulations Report:

The analyzed dosing formulations were within Lab's SOP range for suspensions (85% to 115%) and were homogeneous. The test substance was not detected in the analyzed vehicle formulation that was administered to the control group (Group 1). Results of the analyses of dosing formulations are summarized below.

Table 1. Results of Homogeneity and Concentration Analyses

	Group 2 (50 mg/mL)	Group 3 (250 mg/mL)	Group 4 (375 mg/mL)
Homogeneity and Concentration Assessment of the Formulations	-	-	-
Mean Concentration (mg/mL)	45.4	256	368
RSD (%)	3.0	0.50	1.4
Mean Concentration % of Target	90.8	102	98.0

Table 2. Results of Concentration Analyses

	Group 2 (50 mg/mL)	Group 3 (250 mg/mL)	Group 4 (375 mg/mL)
Final results of preparation	49.4 (98.9)	274 (110)	385 (103)

TABLE 3. SUMMARY OF MATERNAL SURVIVAL AND PREGNANCY STATUS

DOSE GROUP	1	2	3	4
	NO. %	NO. %	NO. %	NO. %
FEMALES ON STUDY	25	25	25	25
FEMALES THAT ABORTED OR DELIVERED	0 0	0 0	0 0	0 0
FEMALES THAT DIED	0 0	0 0	0 0	0 0
FEMALES THAT ABORTED	0 0	0 0	0 0	0 0
NONGRAVID	0 0	0 0	0 0	0 0
GRAVID	0 0	0 0	0 0	0 0
FEMALES THAT WERE EUTHANIZED	0 0	0 0	0 0	0 0
NONGRAVID	0 0	0 0	0 0	0 0
GRAVID	0 0	0 0	0 0	0 0
FEMALES EXAMINED AT SCHEDULED NECROPSY	25 100	25 100	25 100	25 100
NONGRAVID	0 0	0 0	0 0	0 0
GRAVID	25 100	25 100	25 100	25 100
GRAVID WITH RESORPTIONS ONLY	0 0	0 0	0 0	0 0
GRAVID WITH VIABLE FETUSES	25 100	25 100	25 100	25 100
TOTAL FEMALES GRAVID	25 100	25 100	25 100	25 100

   1- 0 MG/KG/DAY 2- 100 MG/KG/DAY 3- 500 MG/KG/DAY 4- 750 MG/KG/ DAY

TABLE: 4. SUMMARY OF LITTER PROPORTIONS OF VARIATIONS % PER LITTER

DOSE GROUP	1	2	3	4
NUMBER OF LITTERS EXAMINED EXTERNALLY	25	25	25	25
NUMBER OF LITTERS WITH FINDINGS	0	0	0	0

1- 0 MG/KG/DAY 2- 100 MG/KG/DAY 3- 500 MG/KG/DAY 4- 750 MG/KG/ DAY

Applicant's summary and conclusion

Conclusions:

No evidence of maternal or developmental toxicity was noted at 100, 500, or 750 mg/kg bw/day. Test substance-related effects were limited to increased incidences of rales, clear material around the mouth, and/or salivation prior to dosing at 500 and 750 mg/kg bw/day. However, in the absence of any other signs of maternal toxicity at these dosage levels, these clinical observations were not considered to be adverse. Based on these results, a dosage level of 750 mg/kg bw/day, the highest dosage level tested, was considered to be the NOAEL for maternal toxicity and embryo/fetal development when N-(3-(trimethoxysilyl)propyl)ethylenediamine was administered orally by gavage to bred Crl:CD(SD) rats.

Executive summary:

The study was carried out to determine the potential of the test substance, N-3-(trimethoxysilyl)propyl)ethylenediamine (CAS No. 1760-24-3), to induce developmental toxicity after maternal exposure from implantation to 1 day prior to expected parturition, to characterise maternal toxicity at the exposure levels tested, and to determine a NOAEL for maternal toxicity and developmental toxicity.

Before administration of test substance to bred female Crl:CD(SD) rats, the analyses of dosing formulations were carried out and were found to be within Lab's SOP range for suspensions (85% to 115%). The test substance in the vehicle (dried and deacidified corn oil) was administered orally by gavage to 3 groups of 25 rats once daily from gestation days 6 through 19. Dose levels were 100, 500, and 750 mg/kg bw/day administered at a dose volume of 2 mL/kg. A concurrent control group composed of 25 bred females received the vehicle on a comparable regimen. The females were approximately 14 weeks of age at the initiation of dose administration. All animals were observed twice daily for mortality and moribundity. Clinical observations, body weights, and food consumption were recorded at appropriate intervals. On gestation day 20, a laparohysterectomy was performed on each female. The uteri, placentae, and ovaries were examined, and the numbers of fetuses, early and late resorptions, total implantations, and corpora lutea were recorded. Gravid uterine weights were recorded, and net body weights and net body weight changes were calculated. The fetuses were weighed, sexed, and examined for external, visceral, and skeletal malformations and developmental variations.

All females in the control, 100, 500, and 750 mg/kg bw/day groups survived to the scheduled necropsy on gestation day 20. Rales and clear material around the mouth approximately 1 hour following dose administration and/or salivation prior to dosing were noted in the 500 and 750 mg/kg bw/day groups during the treatment period. While rales were also noted during the daily examinations, the salivation and clear material around the mouth did not persist to the daily examinations. In the absence of any other signs of maternal toxicity (i.e. effects on survival, body weights, and food consumption) in these groups, the clinical observations and the rales were attributed to test substance administration, but were not considered adverse.

Mean maternal body weights, body weight gains, net body weights, net body weight gains, gravid uterine weights, and food consumption in the 100, 500, and 750 mg/kg bw/day groups were unaffected by test substance administration. There were no test substance-related macroscopic findings noted at any dosage level. Intrauterine growth and survival were unaffected by maternal test substance administration at all dosage levels. There were no test substance-related fetal malformations or developmental variations observed for fetuses at any dosage level.

There was no evidence of maternal or developmental toxicity was noted at 100, 500, or 750 mg/kg bw/day. Test substance-related effects were limited to increased incidences of rales, clear material around the mouth, and/or salivation prior to dosing at 500 and 750 mg/kg/day. However, in the absence of any other signs of maternal toxicity at these dosage levels, these clinical observations were not considered to be adverse. Based on these results, a dosage level of 750 mg/kg bw/day, the highest dosage level tested, was considered to be the no-observed-adverse-effect level (NOAEL) for maternal toxicity and embryo/fetal development when N-(3-(trimethoxysilyl)propyl)ethylenediamine was administered orally by gavage to rats.