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Administrative data

Endpoint:
one-generation reproductive toxicity
Type of information:
experimental study
Adequacy of study:
key study
Study period:
2004-09-06 to 2004-10-25
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2005
Report date:
2005

Materials and methods

Test guidelineopen allclose all
Qualifier:
according to guideline
Guideline:
OECD Guideline 422 (Combined Repeated Dose Toxicity Study with the Reproduction / Developmental Toxicity Screening Test)
Version / remarks:
1996
Deviations:
no
Qualifier:
according to guideline
Guideline:
other: USEPA OPPTS 870.3650
GLP compliance:
yes
Limit test:
no

Test material

Constituent 1
Chemical structure
Reference substance name:
3-(triethoxysilyl)propiononitrile
EC Number:
213-050-5
EC Name:
3-(triethoxysilyl)propiononitrile
Cas Number:
919-31-3
Molecular formula:
C9H19NO3Si
IUPAC Name:
3-(triethoxysilyl)propanenitrile

Test animals

Species:
rat
Strain:
Wistar
Details on species / strain selection:
HanBrl:WIST (SPF)
Sex:
male/female
Details on test animals or test system and environmental conditions:
Rats were obtained from RCC Ltd Laboratory Animal Services, Fullinsdorf, Switzerland.
Animals were a minimum of 8 weeks of age at delivery. Males were 227-271 grams and females were 165-216 grams. Animals were acclimated for 7 days prior to pairing, under test conditions with an evaluation of the health status. Animals rooms were air conditioned with 10-15 air changes per hour; the environment was monitored continuously with recordings of temperature and relative humidity, 12 hours artificial fluorescent light/12 hours dark with background music played at a centrally defined low volume for at least 8 hours during the light period. Animals were housed in Makrolon (R) cages with wire mesh tops and standard granulated softwood bedding. Pelleted standard rat/mouse maintenance diet was available ad libitum. Tap water from Fullinsdorf in bottles was available ad libitum.

Administration / exposure

Route of administration:
oral: gavage
Vehicle:
corn oil
Details on exposure:
The test item was administered once daily, by gavage. All animals received a dose volume of 2 mL/kg body weight with a daily adjustment of the individual volume to the actual body weight. Control animals were dosed with the vehicle alone (dried corn oil)
Details on mating procedure:
Females were paired with males (1:1) from the same treatment group until evidence of mating was obtained (vaginal plug or sperm-positive vaginal smear). Length of cohabitation did not exceed 14 days.
Analytical verification of doses or concentrations:
yes
Details on analytical verification of doses or concentrations:
Samples for determination of actual test item concentrations, stability (7 day) and homogeneity in the prepared mixtures were taken on the first day of preparation. Samples for determination of actual test item concentrations and homogeneity were also taken on one occasion during the gestation period. Analysis were performed using a Gas Chromatographic method.
Duration of treatment / exposure:
Exposure period: Premating (14 days), mating, gestation, and postpartum days 1-3 for a maximum total of 44 days depending on duration of mating phase.
Premating exposure period (males): 14 days
Premating exposure period (females): 14 days
Duration of test: up to a maximum of 44 days
Frequency of treatment:
daily
Details on study schedule:
Animals of both sexes received test article for 14 days prior to pairing and during pairing period. Daily dosing of the females was continued throughout pregnancy and up to day 3 of lactation. Males were dosed for a minimum of 28 days.
Doses / concentrationsopen allclose all
Dose / conc.:
0 mg/kg bw/day (actual dose received)
Remarks:
Group 1
Dose / conc.:
100 mg/kg bw/day (actual dose received)
Remarks:
Group 2
Dose / conc.:
500 mg/kg bw/day (actual dose received)
Remarks:
Group 3
Dose / conc.:
1 000 mg/kg bw/day (actual dose received)
Remarks:
Group 4
No. of animals per sex per dose:
10/sex/group
Control animals:
yes, concurrent vehicle
Details on study design:
3-(Triethoxysilyl)propiononitrile was administered once daily orally (by gavage) to 10 males and 20 females (10 toxicity group and 10 reproductive group females) rats at doses of 100, 500 and 1000 mg/kg bw/day. A concurrent vehicle control group (dried corn oil) was also included.
Males and toxicity group females were sacrificed after they had been treated for at least 28 days; reproductive group females were dosed throughout the prepairing (14 day), pairing and gestation periods until day 3 of lactation up to a maximum of 44 days; reproductive group females and pups were sacrificed on day 4 of lactation.

Details on mating: After a pre-pairing period of 14 days, males and females in the reproductive groups were paired overnight, in the ratio of 1 male to 1 female. The female was placed with the same male until mating occurred or two weeks had elapsed. The day on which spermatozoa was observed was designated day 0 post coitum. After mating was ascertained, the animals were separated and housed individually. The females were allowed to litter and rear their progeny to day 4 of lactation.

Examinations

Parental animals: Observations and examinations:
Parameters assessed during study (maternal and fetal): Maternal body weight, food consumption, and clinical observations.
Clinical observations performed and frequency: General clinical observations were made twice daily to assess external condition, behaviour and mortality/morbidity. Detailed clinical observations were conducted weekly and were performed after the exposure period. Examinations included assessment of external condition, behaviour, autonomic activity, gait and posture. Additionally, the females were observed for signs of difficult or prolonged parturition. The dams were observed daily for survival and behavioural abnormalities in nesting.
Litter observations:
Live birth, stillbirth, any gross abnormalities and weight, litter weight gain, and  macroscopic observations were noted.
Postmortem examinations (parental animals):
Organs examined at necropsy (macroscopic and microscopic): The number  of implantation sites and corpora lutea were determined at necropsy.  
Postmortem examinations (offspring):
Live birth, stillbirth, any gross abnormalities and weight, litter weight gain, and  macroscopic observations were noted.
Statistics:
Statistical methods:  Mean and standard deviations of data of various parameters were calculated. Univariate one-way analysis of variance was used to assess the significance of intergroup differences. Dunnett t-test, based on a pooled variance estimate, was used for intergroup comparisons. The Steel test (rank test)was applied when the data could not be assumed  to follow a normal distribution. Fisher's Exact test for 2x2 tables was applied if the variables could be dichotomized without loss of information. Statistically significant probabilities are reported at either the p<0.05 or p<0.01 levels.
Reproductive indices:
Gonadal function, mating behavior, conception, development of the conceptus and parturition

Results and discussion

Results: P0 (first parental generation)

General toxicity (P0)

Clinical signs:
effects observed, treatment-related
Description (incidence and severity):
Commencing around day 14 of gestation and for the duration of the remaining treatment period, all females of the high dose group showed signs of discomfort after administration of the test article (pushing head through bedding material). During this period, stretched forelimbs were noted on single or few days in six females. For four females, saltatory spasms were noted for up to few days. These clinical signs were considered to be test item-related.
Mortality:
no mortality observed
Body weight and weight changes:
no effects observed
Description (incidence and severity):
No effects were observed in mean absolute or mean weight gains in any of the treated groups. 
Food consumption and compound intake (if feeding study):
no effects observed
Description (incidence and severity):
Mean food consumption was similar in all groups and not affected from treatment. There was a tendency towards slightly higher food consumption in Group 4 but that was considered to be incidental and of no toxicological relevance.
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):
no effects observed
Immunological findings:
not examined
Organ weight findings including organ / body weight ratios:
not examined
Histopathological findings: non-neoplastic:
not examined
Histopathological findings: neoplastic:
not examined
Other effects:
not specified

Reproductive function / performance (P0)

Reproductive function: oestrous cycle:
no effects observed
Description (incidence and severity):
The mean number of corpora lutea per dam (determined at necropsy) was similar in all groups (24.1, 23.5, 23.5 and 24.7 in order of ascending dose level) and gave no indication of a test item-related effect.
Reproductive function: sperm measures:
not specified
Reproductive performance:
no effects observed
Description (incidence and severity):
All females were mated within seven days. The median and mean precoital times were unaffected by treatment with the test item. The fertility rate was generally high and calculated fertility indices were similar in all groups. The gestation index was 100% in all groups.

Details on results (P0)

No treatment-related effects were observed in any of the reproductive parameters evaluated. No effects were observed in mean absolute or mean weight gains in any of the treated groups. Mean food consumption was similar in all groups and not affected from treatment. No abnormal findings were noted in any treated groups during 4 days post-partum. No treatment-related effects were observed in any of the reproductive parameters evaluated. All females produced litters that were similar in all respects to control litters.

Effect levels (P0)

open allclose all
Dose descriptor:
NOAEL
Effect level:
>= 1 000 mg/kg bw/day
Based on:
test mat.
Sex:
male/female
Basis for effect level:
other: no adverse findings for reproductive parameters
Dose descriptor:
NOAEL
Effect level:
100 mg/kg bw/day (actual dose received)
Based on:
test mat.
Sex:
male/female
Basis for effect level:
organ weights and organ / body weight ratios
histopathology: non-neoplastic

Results: F1 generation

General toxicity (F1)

Clinical signs:
no effects observed
Description (incidence and severity):
No abnormal findings were noted at first litter check or during the first 4 days post-partum. Sex ratios were unaffected by treatment at first litter check and during the first four days post-partum.
Mortality / viability:
no mortality observed
Description (incidence and severity):
The number of live pups at first litter check was unaffected by treatment with the test item. The mean number of live pups per litter check was 12.3, 12.1, 13.5 and 11.9 in order of ascending dose level. Neonatal mortality was generally low and not affected by treatment with the test item.
Body weight and weight changes:
no effects observed
Description (incidence and severity):
Mean pup weights at day 0 and day 1 post-partum were unaffected by treatment with the test item
Food consumption and compound intake (if feeding study):
not examined
Food efficiency:
not examined
Water consumption and compound intake (if drinking water study):
no effects observed
Ophthalmological findings:
not examined
Haematological findings:
not examined
Clinical biochemistry findings:
not examined
Urinalysis findings:
not examined
Sexual maturation:
not examined
Anogenital distance (AGD):
not examined
Nipple retention in male pups:
not examined
Organ weight findings including organ / body weight ratios:
not examined
Gross pathological findings:
no effects observed
Description (incidence and severity):
No macroscopic findings were noted during necropsy of F1 pups.
Histopathological findings:
not examined
Other effects:
not specified

Developmental neurotoxicity (F1)

Behaviour (functional findings):
not examined

Developmental immunotoxicity (F1)

Developmental immunotoxicity:
not examined

Effect levels (F1)

Dose descriptor:
NOAEL
Generation:
F1
Effect level:
>= 1 000 mg/kg bw/day
Based on:
test mat.
Sex:
male/female
Basis for effect level:
other: no reproductive toxicity for F1 animals

Overall reproductive toxicity

Reproductive effects observed:
no

Any other information on results incl. tables

Reproduction data: Summary of performance

Table 1: F0 animals breeding for F1 Litters

 Group (mg/kg/day)  1 (0) 2 (100)  3 (500)  4 (1000)
 Number of females paired 10 10  10  10 
 Number of females mated 10  10  10  10 
 Number of pregnant females  10 10  10  9 (A) 
 Number of females delivering pups  10 10 10  9
 Number of females with live pups on day 4 post-partum  10 10  10  9

(A) = Female No 79 was not pregnant

Applicant's summary and conclusion

Conclusions:
In a combined repeated dose oral toxicity study with the reproduction/developmental toxicity screening test with the registered substance 3-(triethoxysilyl)propiononitrile, conducted according to OECD Test Guidelines 422 and in compliance with GLP, a NOAEL for reproductive toxicity was concluded to be greater than or equal to 1000 mg/kg bw/day based on no treatment related effects observed in any of the reproductive parameters evaluated in males and females animals.