Amino functional alkoxysilanes

Developmental toxicity / teratogenicity

Administrative data

Endpoint:

developmental toxicity

Type of information:

experimental study

Adequacy of study:

key study

Study period:

1997-04-14 to 1997-05-01

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

1998

Report date:

1998

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

EPA OTS 798.4900 (Prenatal Developmental Toxicity Study)

Version / remarks:

(Similar to OECD 414)

GLP compliance:

yes

Limit test:

no

Test material

Test material information

Constituent 1

Test animals

Species:

rat

Strain:

other: Charles River Crl:CD VAF/Plus

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Charles River Labs, Portage, MI, USA
- Age at study initiation: not stated
- Weight at study initiation: 235-240 g (day 0 of study)
- Housing: 1/suspended stainless steel cage
- Diet: standard diet ad libitum
- Water: drinking water ad libitum
- Acclimation period: 10 days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 72-75 deg F
- Humidity (%): 44-56
- Photoperiod (hrs dark / hrs light): 12 h/12 h

IN-LIFE DATES: From: 1997-04-14 To: 1997-04-28

Administration / exposure

Route of administration:

oral: gavage

Vehicle:

peanut oil

Details on exposure:

PREPARATION OF DOSING SOLUTIONS: 0.3, 1.5 or 9 g of TS were added to 30 ml vehicle (peanut oil), mixed with magnetic stir bar. Solution said to be stable for 12 h; prepared daily. A constant volume of 2 ml/kg bw of these solutions or the vehicle were administered daily. No tests were conducted on the on homogeneity or stability of prepared solutions.

DIET PREPARATION
no details given

VEHICLE
- Justification for use and choice of vehicle (if other than water): None given (TS hydrolyses in water)
- Concentration in vehicle: 0.3, 1.5 or 9 g of TS in 30 ml vehicle
- Amount of vehicle (if gavage): 2 ml/kg bw
- Lot/batch no.: Sigma Peanut Oil (P-2144); lot 83H0848
- Purity: not stated

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

doses: 20, 100 and 600 mg/kg bw/day
target concentrations: 10, 50, 300 mg/ml
measured average concentration: 9.34, 51.2, 299 mg/ml

Details on mating procedure:

- Impregnation procedure: cohoused
- If cohoused:
- M/F ratio per cage: 1:1
- Length of cohabitation: until copulatory plug or vaginal smear was present.
- Proof of pregnancy: copulatory plug or vaginal smear confirmed mating

Duration of treatment / exposure:

Day 6 of gestation to day 17 of gestation [NB the SIAR (2003) report of this study notes treatment from GD 6 to 20]

Frequency of treatment:

once per day

Duration of test:

Observations from gestation day (GD) 6 to GD 20.

No. of animals per sex per dose:

30 females

Control animals:

yes, concurrent vehicle

Details on study design:

Sex: female
Duration of test: Through day 20 of gestation

Examinations

Maternal examinations:

CAGE SIDE OBSERVATIONS: Yes
- Time schedule: twice daily GD 6-20

DETAILED CLINICAL OBSERVATIONS: Yes
- Time schedule: daily

BODY WEIGHT: Yes
- Time schedule for examinations: GDs 0, 6, 9, 12, 15, 18, 20

FOOD CONSUMPTION : Yes
- Food consumption for each animal determined and mean daily diet consumption calculated as g food/kg bw/day: Yes. determined on GDs 0, 6, 9, 12, 15, 18, 20

POST-MORTEM EXAMINATIONS: Yes
- Sacrifice on GD 20
- Organs examined: laparaohysterectomic examination and necropsy

Ovaries and uterine content:

The ovaries and uterine content were 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 of the fetuses from 0 and 600 mg/kg bw /day groups
- Skeletal examinations: Yes: half per litter from all dose groups
- Head examinations: yes
Other: weight and sex determination

Statistics:

One-way analysis of variance (ANOVA) was used to analyze mean maternal gestation body weights, body weight changes, and food consumption, mean number of corpora lutea, implantation sites, live foetuses(male and female), postimplantation losses, resorptions (early and late), mean fetal weights (male and female), gravid uterine weights, carcass weights, and net weight change from day 0. If the ANOVA was significant, pairwise comparisons to the vehicle control were performed using Dunnett's test. Pairwise comparison with vehicle control (Dunnet, 1964) if ANOVA significant.
A Kruskal-Wallis test was used to analyze mean percent preimplantation losses and live fetuses (male and female) per animal, mean percent postimplantation losses, dead fetuses, and resorptions (early and late) expressed as percentages of implantations per animal, mean percent affected fetuses per litter for external, visceral, and skeletal malformations and developmental variations, and mean percent affected fetuses per liter for external, visceral, and skeletal malformations and developmental variations. If the Kruskal-Wallis test was significant, pairwise comparisons to the vehicle control were made using a Mann-Whitney U test.

A Pearson chi-square test was used to analyze fetal and litter incidence of fetal external, visceral and skeletal malformations and developmental variations, as well as litter incidence of total fetal external, visceral and skeletal malformations and developmental variations. If the chi-square test was significant, pairwise comparisons to the vehicle control were performed using a Fischer's exact test.

Indices:

No data given as indices (see REMARKS ON RESULTS INCLUDING TABLES AND FIGURES for details of reproductive/developmental findings).

Historical control data:

Full historical control data given (Charles River CD).

Results and discussion

Results: maternal animals

General toxicity (maternal animals)

Clinical signs:

effects observed, treatment-related

Description (incidence and severity):

Clinical signs although not restricted to the animals that died, were predominantly observed in these animals exposed to 600 mg/kg/day and included hypoactivity, cold to the touch, body surface stained and material around the mouth and nose. Additionally, respiratory signs including laboured breathing, gasping and rales in the 600 mg/kg/day dose group. No signs were observed in the two lower dose (100 and 20 mg/kg bw/day) groups.

Dermal irritation (if dermal study):

not examined

Mortality:

mortality observed, treatment-related

Description (incidence):

At 600 mg/kg bw/day, 5/30 deaths occurred. Furthermore, 2 rats were found dead on gestation day 7, one rat died on gestation days 13, 15 and 17 respectively.

Body weight and weight changes:

effects observed, treatment-related

Description (incidence and severity):

At 600 mg/kg/day, a slight decrease (not statistically significant) in the body weight gain was observed during gestation days 6 to 9. Since this decrease was consistent with significant decreases in the food consumption, it was considered to be treatment-related observations. No other significant treatment-related effects on the body weight gain were observed at any dose level.

Food consumption and compound intake (if feeding study):

effects observed, treatment-related

Description (incidence and severity):

At 600 mg/kg/day dose level, a statistically significant decrease occurred in the food consumption during gestation days 6 to 9.
A statistically significant decrease in the food consumption were observed at gestation day 19 to 20 at 100 mg/kg/day. However, since no effect was observed at the 600 mg/kg/day dose level in the latter incidence, it was considered to be not treatment-related. No other significant treatment-related effects on the food consumption were observed at any dose level during the treatment period.

Food efficiency:

not specified

Water consumption and compound intake (if drinking water study):

not examined

Ophthalmological findings:

not specified

Haematological findings:

not specified

Clinical biochemistry findings:

not specified

Urinalysis findings:

not specified

Behaviour (functional findings):

no effects observed

Immunological findings:

not examined

Organ weight findings including organ / body weight ratios:

not specified

Gross pathological findings:

no effects observed

Neuropathological findings:

not examined

Histopathological findings: non-neoplastic:

no effects observed

Histopathological findings: neoplastic:

no effects observed

Other effects:

not specified

Maternal developmental toxicity

Number of abortions:

not specified

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:

not specified

Changes in number of pregnant:

no effects observed

Other effects:

no effects observed

Description (incidence and severity):

A statistically significant increase in the mean number of corpora lutea was observed at 600 mg/kg/day, however, it was considered to not be treatment related as ovulation and corpora lutea formation occurred prior to exposure to the test article.

Effect levels (maternal animals)

1

Key result

Dose descriptor:

NOAEL

Effect level:

100 mg/kg bw/day

Basis for effect level:

other: maternal toxicity

2

Key result

Dose descriptor:

LOAEL

Effect level:

600 mg/kg bw/day

Basis for effect level:

other: maternal toxicity

3

Key result

Dose descriptor:

LOAEL

Effect level:

600 mg/kg bw/day

Basis for effect level:

other: developmental toxicity

Results (fetuses)

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:

not specified

External malformations:

no effects observed

Skeletal malformations:

effects observed, treatment-related

Description (incidence and severity):

At 600 mg/kg/day, statistically significant increases in the incidences of the variations 27 presacral vertebrae and sternebrae unossified were observed.

Visceral malformations:

effects observed, non-treatment-related

Description (incidence and severity):

At 100 mg/kg/day, a statistically significant increase in the incidence of the variation extra pair of full ribs was observed, however, since no effects were observed at the 600 mg/kg/day, it was considered to not be treatment-related indices.

Other effects:

not specified

Effect levels (fetuses)

Key result

Dose descriptor:

NOAEL

Effect level:

100 mg/kg bw/day

Based on:

test mat.

Sex:

male/female

Basis for effect level:

other: teratogenicity

Fetal abnormalities

Abnormalities:

effects observed, treatment-related

Localisation:

skeletal: sternum

skeletal: vertebra

Description (incidence and severity):

At 600 mg/kg/day, statistically significant increases in the incidences of the variations 27 presacral vertebrae and sternebrae unossified were observed

Overall developmental toxicity

Developmental effects observed:

yes

Lowest effective dose / conc.:

600 mg/kg bw/day

Treatment related:

yes

Relation to maternal toxicity:

not specified

Dose response relationship:

yes

Relevant for humans:

not specified

Any other information on results incl. tables

Mortality and day of death: 

Dose (mg/kg bw/day)                 No. Dead   Day of Death (gestation day)

0                                              0/30                              -

20                                             0/30                              -

100                                           0/30                              -

600                                           5/30                              7,7,13,15,17

Number pregnant per dose level:

Dose (mg/kg bw/day)                 No. Pregnant

0                                              29/30

20                                             25/30

100                                           26/30

600                                           22/30

Number aborting: none

Number of resorptions: 

Dose (mg/kg bw/day)                 No. Resorptions (early + late)

0                                              34

20                                             25

100                                           38

500                                           25

Number of implantations:
Dose (mg/kg bw/day)                             No. Implantations 

0                                                          437

20                                                         368

100                                                       361

600                                                       358

Pre and post implantation loss:

Dose (mg/kg bw/day)                  Preimplantation loss       Postimplantation loss

0                                                          50                                 34

20                                                         67                                 25

100                                                       74                                 38

600                                                       60                                 25

Number of corpora lutea:

Dose (mg/kg bw/day)                 No. Corpora lutea 

0                                                          487

20                                                         435

100                                                       435

600                                                       418

Duration of Pregnancy: 20 days

Dose (mg/kg bw/day)                           Mean body weight, grams (GD 20)

0                                                                      404.7   

20                                                                     405.1

100                                                                   390.4

600                                                                   407.4

Applicant's summary and conclusion

Conclusions:

A well reported study conducted according to generally accepted scientific standards and in compliance with GLP reported maternal toxicity (increased incidences of mortality, clinical observations, and slight decreases in body weight gain and food consumption) at 600 mg/kg bw/day. The occurrence of maternal toxicity was accompanied by slight fetal toxicity (increased minor skeletal variations). No significant maternal or developmental effects were observed at 20 or 100 mg/kg bw/day. The maternal and developmental NOAEL was 100 mg/kg bw/day.