N-[3-(dimethoxymethylsilyl)-2-methylpropyl]ethylenediamine

Endpoint summary

Key value for chemical safety assessment

Effects on fertility

Description of key information

An extended one generation reproductive toxicity study needs only to be conducted if the available repeated dose toxicity study indicate adverse effects on reproductive organs or tissues or reveal other concerns in relation with reproductive toxicity. In the available 90 -day repeated dose toxicity study with the registration substance in rats no indictation of adverse effects on reproductive organs or tissuers reaveal concerns regarding toxicity to reproductive organs.

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

Effects on developmental toxicity

Description of key information

Oral: Developmental Toxicity Test (OECD 414), rat: NOAEL (maternal) ≥ 400 mg/kg bw/day; NOAEL (embryotoxicity/teratogenicity) ≥ 400 mg/kg bw/day

Link to relevant study records

Reference

Endpoint:

developmental toxicity

Type of information:

experimental study

Adequacy of study:

key study

Study period:

30 Aug 2019 to 30 Jan 2020

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:

June 2018

GLP compliance:

yes

Limit test:

no

Species:

rat

Strain:

other: Crl:CD(SD)

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Charles River Laboratories, Inc., Raleigh, NC
- Age at study initiation: 11 - 12 weeks old
- Weight at study initiation: between 200 and 250 g
- Fasting period before study: not reported
- Housing: individually housed in solid-bottom cages containing appropriate bedding equipped with an automatic watering valve.
- Diet: PMI Nutrition International, LLC Certified Rodent LabDiet® 5002 (meal) was provided ad libitum
- Water: Municipal tap water after treatment by reverse osmosis was freely available to each animal via an automatic watering system.
- Acclimation period: prior to the initiation of dosing.

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 20 - 26
- Humidity (%): 30 - 70
- Air changes (per hr): 10 or more
- Photoperiod (hrs dark / hrs light): 12-hr light/12-hr dark

Route of administration:

oral: gavage

Vehicle:

corn oil

Details on exposure:

PREPARATION OF DOSING SOLUTIONS: The dosing formulations were prepared every 4 days and an adequate amount of each formulation was dispensed into daily aliquots, which were stored at room temperature, protected from light, under nitrogen, until use.

VEHICLE
- Lot/batch no. (if required): 2IC0148

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

The analyzed dosing formulations contained 107% to 114% of the test substance which was within the protocol-specified range of target concentrations for suspensions (85% to 115%) and were homogeneous.

Details on mating procedure:

- Impregnation procedure: purchased timed pregnant

Duration of treatment / exposure:

single daily oral gavage dose during Gestation Days 6 through 20

Frequency of treatment:

single daily dose

Duration of test:

from Gestation Days 6 through 20

Dose / conc.:

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

Dose / conc.:

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

Dose / conc.:

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

No. of animals per sex per dose:

25 dams/dose

Control animals:

yes, concurrent vehicle

Details on study design:

- Dose selection rationale: Doses were based on a dose range-finding study, in which 5 males and 5 females (non-pregnant) Sprague Dawley rats per dose group via oral gavage for up to 14 consecutive days at dosage levels of 0, 90, 180, 300, and 500 mg/kg bw/day. At 500 mg/kg/day, the test substance caused moribundity, leading to unscheduled euthanasia, and thus exceeds a maximum tolerated dose. Therefore, the dose levels selected for this study were 0, 50, 150, and 400 mg/kg bw/day.
- Rationale for animal assignment: Animals were assigned to groups by a stratified randomization scheme designed to achieve similar group mean body weights. Animals in poor health or at extremes of body weight range were not assigned to groups.

Maternal examinations:

CAGE SIDE OBSERVATIONS: Yes
- Time schedule: twice daily, once in the morning and once in the afternoon.
- Cage side observations included, but were not limited to: labored breathing, fur staining, thinning fur, abnormal gait, decreased activity, and increased salivation.

DETAILED CLINICAL OBSERVATIONS: Yes
- Time schedule: once daily, beginning on the day of receipt and lasting through euthanasia

BODY WEIGHT: Yes
- Time schedule for examinations: individually on Gestation Days 0 (by supplier) and 5 - 21 (daily)

FOOD CONSUMPTION AND COMPOUND INTAKE: Yes
- 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

WATER CONSUMPTION AND COMPOUND INTAKE: No

POST-MORTEM EXAMINATIONS: Yes
- Sacrifice on gestation day # 21
- Organs examined: liver and kidneys

OTHER: Blood samples for thyroid hormone analyses were collected (prior to noon in order to avoid diurnal fluctuations in thyroid hormone levels) via a jugular vein into tubes without anticoagulant

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
- Other: Placentae were also examined

Fetal examinations:

- External examinations: Yes: all per litter
- Soft tissue examinations: Yes: half per litter
- Skeletal examinations: Yes: half per litter
- Head examinations: Yes: half per litter

Statistics:

All statistical tests were conducted at the 5% significance level. All pairwise comparisons were conducted using two sided tests and are reported at the 1% and 5% levels.

Body weight; body weight gain; food consumption; gravid uterine weight and corrected maternal body weights; litter means; organ weights; and anogenital distance: Levene's test was used to assess the homogeneity of group variances. The groups were compared using an overall one-way ANOVA F-test if Levene's test was not significant or the Kruskal-Wallis test if it was significant. If the overall F-test or Kruskal-Wallis test was found to be significant, then pairwise comparisons were conducted using Dunnett's or Dunn's test, respectively.

Ovarian and uterine content; litter % of fetuses with external/visceral/skeletal abnormalities: The groups were compared using an overall Kruskal-Wallis test. If the overall Kruskal-Wallis test was found to be significant, then the above pairwise comparison was conducted using Dunn's test.

Parental indices and mortality; macroscopic findings; microscopic findings: A Fisher’s Exact Test was used to conduct pairwise group comparisons of interest.

Thyroid hormone analysis: The groups were compared using an overall one-way ANOVA F-test. If the overall F-test is found to be significant, then pairwise comparisons will be conducted using Dunnett's test.

Indices:

Postimplantation Loss/Litter = (No. Dead Fetuses, Resorptions (Early or Late) per Group) / (No. Gravid Females per Group) X 100
Summation Per Group (%) = (Sum of Postimplantation Loss per Litter) / (No. Litters per Group) X 100
Postimplantation Loss/Litter (%) = (No. Dead Fetuses, Resorptions (Early or Late) per Group) / (No. Implantation Sites per Litter) X 100

Historical control data:

Charles River Ashland has historical data on the background incidence of fetal malformations and developmental variations in the Crl:CD(SD) rat.

Clinical signs:

effects observed, treatment-related

Description (incidence and severity):

Labored breathing and/or abnormal breathing sounds were noted for 17 of 25 females in the 400 mg/kg bw/day group at the daily examinations and/or 1 - 2 hours following dose administration generally throughout the study (Gestation Days 8 - 21). Abnormal breathing sounds were also noted for 8 of 25 females in the 150 mg/kg bw/day group during Gestation Days 7 - 19, albeit to a lesser extent than noted in the 400 mg/kg bw/day group.

Dermal irritation (if dermal study):

not examined

Mortality:

mortality observed, non-treatment-related

Description (incidence):

One female in the 150 mg/kg bw/day group was found dead on gestation day 18. No clinical observations or noteworthy changes in body weight were noted for this female prior to death, and no macroscopic findings were observed at necropsy. In the absence of unscheduled deaths in the high-dose group, this mortality was not considered test substance-related.

Body weight and weight changes:

effects observed, non-treatment-related

Description (incidence and severity):

Mean maternal body weights, body weight gains, corrected body weights, corrected body weight gains, and gravid uterine weights in the 50, 150, and 400 mg/kg bw/day groups were unaffected by test substance administration. Differences from the control group were slight and not statistically significant, with the following exceptions. A statistically significantly higher mean body weight gain during Gestation Days 6 - 7 and lower mean body weight gain during Gestation Days 20 - 21 were noted in the 400 mg/kg bw/day group compared to the control group. Because these body weight changes failed to produce a noteworthy effect on the overall body weight gain and absolute mean body weights in this group, they were considered transient and unrelated to test substance administration.

Food consumption and compound intake (if feeding study):

effects observed, non-treatment-related

Description (incidence and severity):

Mean maternal food consumption, evaluated as g/animal/day and g/kg/day, in the 50, 150, and 400 mg/kg bw/day groups was unaffected by test substance administration. Differences from the control group were slight and not statistically significant.

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

Gross pathological findings:

no effects observed

Neuropathological findings:

not examined

Histopathological findings: non-neoplastic:

no effects observed

Histopathological findings: neoplastic:

not examined

Other effects:

effects observed, non-treatment-related

Description (incidence and severity):

No test substance-related effects on mean TSH, T3, or T4 concentrations were noted at any dose level. Mean TSH concentration in the 400 mg/kg bw/day group females was 21.8% lower than the control group. This decrease was not considered test substance-related because the difference from the control group was not statistically significant, and there were no effects on thyroid gland weight or histopathology in the thyroid at this dose level.

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 specified

Details on maternal toxic effects:

Intrauterine growth and survival were unaffected by test substance administration at dose levels of 50, 150, and 400 mg/kg bw/day. Parameters evaluated included mean litter proportions of postimplantation loss, mean number of viable/live fetuses, mean fetal body weights, and fetal sex ratios. Differences from the control group were slight, not statistically significant, and/or did not occur in a dose-related manner.

Mean numbers of corpora lutea and implantation sites and the mean litter proportions of pre-implantation loss were similar across all groups.

Key result

Dose descriptor:

NOAEL

Effect level:

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

Based on:

test mat.

Basis for effect level:

other: No adverse effects observed

Key result

Abnormalities:

effects observed, non-treatment-related

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):

No test substance-related skeletal malformations were observed in fetuses in this study. Two fetuses in the 150 mg/kg bw/day group each had an absent lumbar vertebra. This finding was not considered test substance-related because no skeletal malformations were noted in the high-dose group. No other skeletal malformations were noted in this study.

Visceral malformations:

effects observed, non-treatment-related

Description (incidence and severity):

No test substance-related visceral malformations were observed in fetuses in this study. One fetus in the 50 mg/kg bw/day group had a retroesophageal right subclavian artery; however, this finding was not observed in a dose-related manner, and therefore was not considered test substance-related. No other visceral malformations were noted in this study.

Other effects:

no effects observed

Description (incidence and severity):

Mean anogenital distance (absolute and relative to cube root of body weight) was unaffected by test substance administration at all dose levels. Differences from the control group were slight and not statistically significant.

Details on embryotoxic / teratogenic effects:

Mean mean number of viable/live fetuses, mean fetal body weights, and fetal sex ratios were unaffected by treatment. Mean anogenital distance (absolute and relative to cube root of body weight) was unaffected by test substance administration at all dose levels. No test substance-related skeletal or visceral malformations were observed in fetuses in this study.

Key result

Dose descriptor:

NOAEL

Effect level:

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

Based on:

test mat.

Sex:

male/female

Basis for effect level:

other: No adverse effects observed

Key result

Abnormalities:

effects observed, non-treatment-related

Key result

Developmental effects observed:

no

Conclusions:

In an oral gavage developmental study conducted in accordance to OECD 414 and to GLP, the NOAEL for N-[3-(dimethoxymethylsilyl)-2-methylpropyl]ethylenediamine for maternal toxicity and embryo/fetal development was 400 mg/kg bw/day, as no significant adverse effects were observed up to the highest dose of 400 mg/kg bw/day tested in rats.

Effect on developmental toxicity: via oral route

Endpoint conclusion:

no adverse effect observed

Dose descriptor:

NOAEL

400 mg/kg bw/day

Study duration:

subacute

Species:

rat

Quality of whole database:

The study was conducted according to the OECD test guideline 414, 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 oral gavage study conducted in accordance to OECD 414 study guidelines and GLP standards, pregnant female rats were exposed with N-[3-(dimethoxymethylsilyl)-2-methylpropyl]ethylenediamine (CAS 23410-40-4) during gestation days 6 through 20 at dose levels of 0, 50, 150, or 400 mg/kg bw/day.

With regards to maternal toxicity, no test substance-related effects on survival were noted at any dosage level. One female in the 150 mg/kg bw/day group was found dead on gestation day 18. No clinical observations or noteworthy changes in body weight were noted for this female prior to death, and no macroscopic findings were observed at necropsy. In the absence of unscheduled deaths in the high-dose group, this mortality was not considered test substance-related. Labored breathing and/or abnormal breathing sounds were observed generally throughout the study (gestation days 7–21) in 8 out of 25 females in the 150 mg/kg bw/day group and 17 out of 25 females in the 400 mg/kg bw/day group. These observations were considered test substance-related due to the absence in control group animals, but non-adverse, as the overall health and well-being of the animals were not impacted by these clinical observations. Mean maternal body weights, body weight gains, corrected body weights, corrected body weight gains, gravid uterine weights, and food consumption in the 50, 150, and 400 mg/kg bw/day groups were unaffected by test substance administration. Thyroid hormones (T3, T4, and TSH) were unaffected by test substance administration at 50, 150, and 400 mg/kg/day. There were no test substance-related macroscopic or microscopic findings or effects on organ weights noted at any dose level. 

Intrauterine growth and survival and fetal anogenital distance were not affected by test substance administration at any dose level. There were no test substance-related fetal malformations or developmental variations noted at any dose level.

In conclusion, based on the absence of adverse maternal and embryo/fetal effects in this study, the dosage level of 400 mg/kg/day was considered to be the no-observed-adverse-effect level (NOAEL) for maternal toxicity and embryo/fetal development when N-[3-(dimethoxymethylsilyl)-2-methylpropyl]ethylenediamine (CAS 23410-40-4) was administered orally by gavage to time-mated Crl:CD(SD) rats.

Justification for classification or non-classification

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