3-(triethoxysilyl)propiononitrile

Endpoint summary

Key value for chemical safety assessment

Effects on fertility

Description of key information

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 Guideline 422 and in compliance with GLP, a NOAEL for maternal and reproductive toxicity was concluded to be = 1000 mg/kg bw/day based on no treatment-related effects observed in any of the reproductive parameters evaluated (RCC Ltd, 2005).

Link to relevant study records

Reference

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

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

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.

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.

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.

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

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: 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.

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.

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

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

Behaviour (functional findings):

not examined

Developmental immunotoxicity:

not examined

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

Reproductive effects observed:

no

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

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.

Effect on fertility: via oral route

Endpoint conclusion:

no adverse effect observed

Dose descriptor:

NOAEL

1 000 mg/kg bw/day

Study duration:

subacute

Species:

rat

Additional information

The key study for reproductive toxicity is the only study available for this endpoint.

In this combined repeated dose oral toxicity study with the reproduction/developmental toxicity screening test, conducted according to OECD Test Guideline 422 and in compliance with GLP, 3-(triethoxysilyl)propiononitrile was administered orally by gavage to rats at dosages of 0, 100, 500 and 1000 mg/kg bw/day. Males and females of the toxicity group were treated for 28 days, females of the reproductive groups were treated for two weeks prior to pairing, during gestation and until day 3 of the lactation period.

There were no treatment-related effects on precoital time, fertility indices, mean duration of gestation, number of implantations, post-implantation loss, pup survival or litter size from birth through scheduled sacrifice on day 4 post-partum at any dosage. Based on the results of this screening study, the NOAEL for reproductive toxicity of 3-(triethoxysilyl)propiononitrile in the rat via oral dosing was determined to be greater than or equal to 1000 mg/kg bw/day (RCC Ltd, 2005)

Effects on developmental toxicity

Description of key information

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 Guideline 422 and in compliance with GLP, a NOAEL for maternal and developmental toxicity was concluded to be =1000 mg/kg bw/day based on no treatment-related effects observed in any of the developmental parameters evaluated (RCC Ltd, 2005)

Link to relevant study records

Reference

Endpoint:

developmental 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

Qualifier:

according to guideline

Guideline:

other: USEPA OPPTS 870.3650

Qualifier:

according to guideline

Guideline:

other: OECD 422

Version / remarks:

1996

Deviations:

no

GLP compliance:

yes

Limit test:

no

Species:

rat

Strain:

Wistar

Remarks:

HanBrl:WIST (SPF)

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.

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)

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.

Details on mating procedure:

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.

Duration of treatment / exposure:

Pre-mating (14 days), mating, gestation, and postpartum days 1-3 for a maximum total of 44 days depending on duration of mating phase.

Frequency of treatment:

daily

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/dose

Control animals:

yes, concurrent vehicle

Details on study design:

Sex: male/female
Duration of test: up a maximum total of 44 days
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.

Maternal examinations:

The dams and pups were observed daily for survival and behavioural abnormalities in nursing. No tissues were collected from the dams or pups for microscopic examination.

Ovaries and uterine content:

Organs examined at necropsy (macroscopic and microscopic): The number of implantation sites and corpora lutea were determined at necropsy.

Fetal examinations:

Pup litter size,  any gross abnormalities and weight, sex ratios, pup viability, litter  weight gain, and macroscopic observations. The dams and pups were observed daily for survival and behavioural abnormalities in nursing. Macroscopic examination was performed at necropsy for the pups.  No tissues were collected from the dams or pups for microscopic examination.

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. For pup data, the litter is the appropriate unit for statistical comparison. Statistically significant probabilities are reported at either the p<0.05 or p<0.01 levels.

Indices:

Gonadal function, mating behaviour, conception, development of the conceptus and parturition

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.

Dermal irritation (if dermal study):

not examined

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.

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

Behaviour (functional findings):

not examined

Immunological findings:

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 macroscopic examination.

Neuropathological findings:

not examined

Histopathological findings: non-neoplastic:

not examined

Histopathological findings: neoplastic:

not examined

Other effects:

not specified

Number of abortions:

no effects observed

Pre- and post-implantation loss:

no effects observed

Description (incidence and severity):

The mean number of implantations per litter and post-implantation loss were unaffected by treatment. The mean numbers of implantations per dam were 13.7, 13.5, 14.2 and 13.6 in order of ascending dose level. The mean incidence of post-implantation loss as a percentage of total implantations was 10.2, 10.4, 4.9 and 12.3% in order of ascending dose level.

Total litter losses by resorption:

no effects observed

Early or late resorptions:

not specified

Dead fetuses:

no effects observed

Description (incidence and severity):

Neonatal mortality was generally low and not affected by treatment with the test item. The total numbers of pup loss during the first four days of life were 1, 2, 3 and 3 in order of ascending dose level, corresponding to 0.8, 1.7, 2.2 and 2.8% of living pups.

Changes in pregnancy duration:

no effects observed

Description (incidence and severity):

The duration of gestation was unaffected by treatment. Mean duration of gestation was 21.6, 21.6, 21.7 and 21.7 days, in order of ascending dose level.

Changes in number of pregnant:

no effects observed

Description (incidence and severity):

Number of pregnant per dose level:  10, 10, 10 and  9 (one female was not pregnant) for 0, 100, 500 and 1000 mg/kg bw/day

Other effects:

not specified

Key result

Dose descriptor:

NOAEL

Effect level:

>= 1 000 mg/kg bw/day (actual dose received)

Based on:

test mat.

Basis for effect level:

other: no adverse findings related to development in maternal animals

Dose descriptor:

NOAEL

Effect level:

ca. 100 mg/kg bw/day

Based on:

test mat.

Basis for effect level:

histopathology: non-neoplastic

organ weights and organ / body weight ratios

Fetal body weight changes:

no effects observed

Reduction in number of live offspring:

no effects observed

Description (incidence and severity):

Neonatal mortality was generally low and not affected by treatment with the test item. The total numbers of pup loss during the first four days of life were 1, 2, 3 and 3 in order of ascending dose level, corresponding to 0.8, 1.7, 2.2 and 2.8% of living pups.

Changes in sex ratio:

no effects observed

Changes in litter size and weights:

no effects observed

Changes in postnatal survival:

no effects observed

Key result

Dose descriptor:

NOAEL

Effect level:

>= 1 000 mg/kg bw/day

Based on:

test mat.

Sex:

male/female

Basis for effect level:

other: based on no adverse developmental effects in pups

Abnormalities:

no effects observed

Developmental effects observed:

no

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

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, the NOAEL for developmental 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 developmental parameters evaluated.

Effect on developmental toxicity: via oral route

Endpoint conclusion:

no adverse effect observed

Dose descriptor:

NOAEL

1 000 mg/kg bw/day

Study duration:

subacute

Species:

rat

Additional information

The key study for developmental toxicity is the only study available for this endpoint.

In this combined repeated dose oral toxicity study with the reproduction/developmental toxicity screening test, conducted according to OECD Test Guideline 422 and in compliance with GLP, 3-(triethoxysilyl)propiononitrile was administered orally by gavage to rats at dosages of 0, 100, 500 and 1000 mg/kg bw/day. Males and females of the toxicity group were treated for 28 days, females of the reproductive groups were treated for two weeks prior to pairing, during gestation and until day 3 of the lactation period.

No abnormal findings were noted for pups at first litter check or during the first 4 days post-partum. Sex ratios at first litter check and on day 4 post-partum were unaffected by treatment with the test item. Mean pup weights on day 0 and day 1 post-partum were unaffected by treatment with the test item. Mean pup weight development during the first 4 days post-partum lactation was unaffected by treatment with the test item. No macroscopic findings were noted during necropsy of F1 pups.

Based on the results of this screening study, the NOAEL for developmental toxicity of 3-(triethoxysilyl)propiononitrile in the rat via oral dosing was determined to be greater than or equal to 1000 mg/kg bw/day (RCC Ltd, 2005)

Justification for classification or non-classification

Based on the available data 3-(triethoxysilyl)propiononitrile is not classified for reproductive or developmental toxicity according to Regulation (EC) No 1272/2008