3-(triethoxysilyl)propanethiol

Developmental toxicity / teratogenicity

Administrative data

Endpoint:

developmental toxicity

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2020/08/24 - 2022/07/20

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2022

Report date:

2022

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 414 (Prenatal Developmental Toxicity Study)

GLP compliance:

yes

Limit test:

no

Test material

Test material information

Constituent 1

Reference substance name:

3-(triethoxysilyl)propanethiol

EC Number:

238-883-1

EC Name:

3-(triethoxysilyl)propanethiol

Cas Number:

14814-09-6

Molecular formula:

C9H22O3SSi

IUPAC Name:

3-(triethoxysilyl)propane-1-thiol

Test material form:

liquid

Test animals

Species:

rat

Strain:

Wistar

Remarks:

Han

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Charles River Laboratories Deutschland, Sulzfeld, Germany
- Age at study initiation: 11-15 weeks
- Weight at study initiation: 192-272 g
- Fasting period before study: No
- Housing: Individually in Macrolon plastic cages (MIII type)
- Diet: Pelleted rodent diet (SM R/M-Z from SSNIFF), ad libitum
- Water: Municipal tap water, ad libitum
- Acclimation period: At least 5 days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 21
- Humidity (%): 51-65
- Air changes (per hr): 10 or more
- Photoperiod (hrs dark / hrs light): 12/12

IN-LIFE DATES: From: 2020/09/29 and 2020/10/01 To: 2020/10/22

Administration / exposure

Route of administration:

oral: gavage

Vehicle:

corn oil

Remarks:

dried and deacidified

Details on exposure:

PREPARATION OF DOSING SOLUTIONS:
Test item dosing formulations (w/w) were homogenized to visually acceptable levels at appropriate concentrations to meet dose level requirements. The dosing formulations were prepared at least weekly as a solution, filled out in daily portions and stored in the refrigerator.

The dosing formulations were removed from the refrigerator and stirred at room temperature for at least 30 minutes before dosing and dosed within 24 hours after removal from the refrigerator. Test item dosing formulations were kept at room temperature until dosing. If practically possible, the dosing formulations and vehicle were continuously stirred until and during dosing.

Adjustment was made for specific gravity of the test item and vehicle. No correction was made for the purity/composition of the test item.

VEHICLE
- Justification for use and choice of vehicle: Trial preparations were performed at the Test Facility to select the suitable vehicle
- Concentration in vehicle: 0, 25, 75, 250 mg/ml
- Amount of vehicle (if gavage): 4 ml/kg bw dose volume
- Lot/batch no.: Not specified
- Purity: Not specified

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

Dose formulation samples were collected for analysis during week 1, with samples for all dose groups analysed for concentration and samples for group 2 (100 mg/kg bw/day) and group 4 (1000 mg/kg bw/day) analysed for homogeneity. Duplicate sets of samples (approximately 500 mg) were sent to the analytical laboratory. Analyses were performed using a validated analytical procedure.

Details on mating procedure:

The female animals arrived at the Test Facility on day 0 or day 1 post-coitum, with day 0 post-coitum defined as the day of successful mating.

Duration of treatment / exposure:

Day 6 to 20 post-coitum, inclusive

Frequency of treatment:

Once daily

Duration of test:

Day 0 or 1 post-coitum through sacrifice on day 21 post-coitium

Doses / concentrations

Doses / concentrations 1

Dose / conc.:

0 mg/kg bw/day (nominal)

Doses / concentrations 2

Dose / conc.:

100 mg/kg bw/day (nominal)

Doses / concentrations 3

Dose / conc.:

300 mg/kg bw/day (nominal)

Doses / concentrations 4

Dose / conc.:

1 000 mg/kg bw/day (nominal)

No. of animals per sex per dose:

22F

Control animals:

yes

Details on study design:

- Dose selection rationale: Based on the results of the dose range finder (7.5.141)
- Rationale for animal assignment: Random

Examinations

Maternal examinations:

MORTALITY: Yes
- Observed for general health/mortality and moribundity twice daily, in the morning and at the end of the working day

CAGE SIDE OBSERVATIONS: Yes
- Once daily, beginning on day 6 post-coitum up to the day prior to necropsy

DETAILED CLINICAL OBSERVATIONS: Yes
- Weekly, out of cage, beginning during pre-treatment period, and on the day of necropsy

BODY WEIGHT: Yes
- Animals were weighed individually on days 2, 6, 9, 12, 15, 18 and 21 post-coitum

FOOD CONSUMPTION: Yes
- Quantitatively measured for days 2-6, 6-9, 9-12, 12-15, 15-18 and 18-21 post-coitum

WATER CONSUMPTION: Yes
- Monitored on regular basis throughout the study by visual inspection of the water bottles/containers

HAEMATOLOGY: No

CLINICAL CHEMISTRY: Yes
- All F0 animals (except those sacrificed in extremis or that delivered their offspring early), analysis for triiodothyronine (T3), thyroxine (T4), and thyroid-Stimulating Hormone (TSH), on the day of scheduled necropsy, animals were not fasted

SACRIFICE
- Animals surviving until scheduled euthanasia or those sacrificed in extremis were euthanized by a carbon dioxide inhalation (gradual fill) procedure
- Terminal procedures are summarized in Table 1 below

ORGAN WEIGHT: Yes
- Thyroid gland (paired) was weighed at necropsy for all animals surviving to scheduled euthanasia
- Ratios of organ to body weight (day 21 post-coitum) were calculated

GROSS PATHOLOGY: Yes
- All animals (except those sacrificed early or who delivered early) were subjected to an external, thoracic and abdominal examination, with special attention being paid to the reproductive organs
- Any macroscopic abnormalities were recorded, collected and fixed in 10% buffered formalin (neutral phosphate buffered 4% formaldehyde solution)

HISTOPATHOLOGY: Yes
- Thyroid glands of all animals were embedded in paraffin, sectioned, mounted on glass slides, and stained with hematoxylin and eosin. Thyroid glands that were supposed to be microscopically evaluated per protocol but were not available on the slide (and therefore not evaluated) are listed in the pathology report as not present. These missing tissues did not affect the outcome or interpretation of the pathology portion of the study because enough tissues were available.
- No macroscopic abnormalities were identified, thus no further tissues were subject to histopathology

Ovaries and uterine content:

Ovaries and uterine horn of all animals were dissected and content examined as quickly as possible after termination. Examinations included:
- Gravid uterus weight: Yes, for animals surviving to scheduled euthanasia
- Number of corpora lutea: Yes
- Number of implantations: Yes
- Number of early resorptions: Yes
- Number of late resorptions: Yes
- Number of live and dead foetuses: Yes

Fetal examinations:

SACRIFICE
- Live foetuses euthanized by administration of sodium pentobarbital into the oral cavity using a small metal feeding tube
- Pups of females that delivered early (female no. 25) or required early sacrifice (female no. 88) were euthanized by decapitation

FOETAL EXAMINATION: Yes
- Litters of females surviving to scheduled necropsy: Detailed external, visceral and skeletal examinations, recorded as variations or malformations
- Pups of females that delivered early or required early sacrifice: Gross external exam

EXTERNAL EXAMINATION: Yes
- Each viable foetus was sexed, examined in detail to detect macroscopic visible abnormalities and their weight (not foetuses of female no. 88 sacrificed before planned necropsy) was determined
- Anogenital distance (AGD) was measured for all viable foetuses, normalized to the cube root of foetal body weight
- For late resorptions, a gross external examination was performed

VISCERAL EXAMINATION: Yes
- Sex of all foetuses was confirmed by internal examination and approximately one-half of the foetuses in each litter (all groups) were examined for visceral anomalies by dissection in the fresh (non-fixed) state.
- Thoracic and abdominal cavities were opened and dissected using a technique described by Stuckhardt and Poppe. This examination included the heart and major vessels. Foetal kidneys were also examined and graded for renal papillae development as described by Woo and Hoar.
- Abnormalities were collected and fixed in 10% buffered formalin at discretion of the Study Director
- Heads were removed from this one-half of the foetuses in each litter and placed in Bouin's solution for soft-tissue examination using the Wilson sectioning technique
- After examination, tissues with variations or malformations were stored in 10% formalin

SKELETAL EXAMINATION: Yes
- All foetuses were eviscerated, followed by fixation in 96% aqueous ethanol, and maceration in potassium hydroxide. Thereafter, they were stained with Alizarin Red S by a method similar to Dawson.
- Skeletal examination was done for one-half of the foetuses (i.e. the foetuses with heads)
- All specimens were archived in glycerin with bronopol as preservative
- A few bones were not available for skeletal examination because they were accidentally damaged or lost during processing, listed in the raw data, no influence on skeletal or overall study findings

Statistics:

Varied by endpoint / dataset evaluated and included:
-Descriptive: Means, standard deviations (or % coefficient of variation or standard error, when deemed appropriate), ratio, percentages, numbers, and/or incidences were reported as appropriate by dataset
- Parametric, non-parametric, incidence methods: Collectively, Levene’s test, one-way ANOVA F-test, Kruskal-Wallis test, Dunnett’s or Dunn’s test, analysis of covariance (ANCOVA), and Fisher’s exact test
- All statistical tests conducted at the 5% significance level
- All pairwise comparisons conducted using two sided tests and were reported at the 1% or 5% levels. Pairwise comparisons were made for: group 2 (100 mg/kg bw/day), group 3 (300 mg/kg bw/day), and group 4 (1000 mg/kg bw/day), each versus group 1 (control).

Indices:

MATERNAL:
- Pregnancy Rate (%): No. of pregnant females x 100 / No. of mated females

FOETAL:
- Male Foetuses (%): No. male foetuses x 100 / No. of foetuses
- Female Foetuses (%): No. female foetuses x 100 / No. of foetuses
- Pre-Implantation Loss (%): No. of corpora lutea – No. of implantations x 100 / No. of corpora lutea
- Post-Implantation Loss (%): No. of implants – No. of live foetuses x 100 / No. of implantations
- Litter % of Foetuses with Abnormalities: No. of foetuses in litter with a given finding x 100 / No. of foetuses in litter examined

Historical control data:

Yes, for this endpoint:
- Viable foetuses/dam, pregnant Wistar Han rats (period 2016-2020)

Results and discussion

Results: maternal animals

General toxicity (maternal animals)

Clinical signs:

effects observed, treatment-related

Description (incidence and severity):

Test item-related clinical signs that were considered adverse were seen at 1000 mg/kg bw/day. All other findings were considered not related to the test item, or not toxicologically relevant.

At 1000 mg/kg bw/day:
- Erect fur, all animals at 1000 mg/kg bw/day, from day 8 post-coitum onwards
- Hunched posture, 21/22 animals at 1000 mg/kg bw/day, from day 8 post-coitum onwards

Dermal irritation (if dermal study):

not examined

Mortality:

mortality observed, treatment-related

Description (incidence):

One mortality was considered adverse. Female no. 88 (1000 mg/kg bw/day) was euthanized early on day 20 post-coitum, as an early delivery was suspected. Findings for this female included: red liquid (assumed blood) in vaginal area / cage, clinical signs from day 7 until day prior to euthanasia (erect fur, hunched posture and salivation, lower body weight gain compared to other 1000 mg/kg bw/day animals (- 86.8% on days 15-18 post-coitum), moderately decreased food consumption, and thyroid microscopic findings (minimal ultimobranchial, unilateral cyst and minimal bilateral follicular cell hypertrophy). Uterus content consisted of single live foetus and 12 early resorptions, with no empty implantation sites. No abnormalities seen at necropsy.

The early delivery (and euthanasia) of a second female (no. 25, 100 mg/kg bw/day) on day 21 post-coitum (i.e. the day of scheduled necropsy) was not considered test item-related.

Body weight and weight changes:

effects observed, treatment-related

Description (incidence and severity):

Decreased body weight, body weight gain, and body weight gain corrected for gravid uterine weight were observed at 1000 mg/kg bw/day and considered adverse. Corrected body weight gain at 100 and 300 mg/kg bw/day was unaffected by test item treatment.

At 1000 mg/kg bw/day:
- Slight mean body weight loss (-3.5%), days 6-9 post-coitum, with body weight loss (up to -4.8%) in 16/22 individual animals
- Significant lower mean body weight compared to controls, from day 9 post-coitum (up to 20% on day 21 post-coitum)
- Significantly lower mean body weight gain compared to controls, from day 9 post-coitum (up to 61% lower on days 18-21 post coitum)
- Based on body weight gain corrected for gravid uterus weight, significant body weight loss compared with controls (-132.0%)

Food consumption and compound intake (if feeding study):

effects observed, treatment-related

Description (incidence and severity):

Lower food consumption was seen at 1000 mg/kg bw/day and considered adverse. Food consumption at 300 and 100 mg/kg bw/day was considered unaffected by treatment.

At 1000 mg/kg bw/day:
- Lower food consumption compared to controls, from days 6-9 post-coitum (up to -41% over days 18-21 post-coitum)

Food efficiency:

not examined

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

not specified

Description (incidence and severity):

Water consumption was monitored by visual inspection of water bottles/containers, results not reported

Ophthalmological findings:

not examined

Haematological findings:

not examined

Clinical biochemistry findings:

effects observed, treatment-related

Description (incidence and severity):

Lower T3 and T4 serum levels were measured at 1000 mg/kg bw/day. Other T3 and T4 findings not considered related to treatment. No effect on TSH.

At 1000 mg/kg bw/day:
- Significantly decreased mean total T3 and T4 serum levels compared to controls (0.45x and 0.47x of control, respectively)

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):

There were no test item-related alterations in thyroid gland weight.

Gross pathological findings:

no effects observed

Description (incidence and severity):

There were no test item-related gross observations in the thyroid glands, with these findings in the background range for rats of this age and strain.

Other findings noted among control and/or treated animals were within the range of biological variation for rats of this age and strain and considered of no toxicological significance.

Neuropathological findings:

not examined

Histopathological findings: non-neoplastic:

effects observed, treatment-related

Description (incidence and severity):

Except for an increase in thyroid follicular cell hypertrophy (considered non-adverse), there were no test item-related microscopic changes in the thyroid. All other thyroid findings were within the background range for rats of this age and strain.

At 1000 mg/kg bw/day:
- Increase incidence of follicular cell hypertrophy of the thyroid gland, all recorded at minimal degree and regarded non-adverse

See summary Table 2 below.

Histopathological findings: neoplastic:

not examined

Other effects:

no effects observed

Maternal developmental toxicity

Number of abortions:

not examined

Pre- and post-implantation loss:

effects observed, treatment-related

Description (incidence and severity):

Due to increased early resorptions, an increased post-implantation loss was estimated for 300 and 1000 mg/kg bw/day (no effect at 100 mg/kg bw/day). No effect on estimated pre-implantation loss.

At 1000 mg/kg bw/day:
- Increased mean post-implantation loss compared to controls (9.35% vs. 4.90% in controls)

At 300 mg/kg bw/day:
- Increased mean post-implantation loss compared to controls (8.51% vs. 4.90% in controls)

Total litter losses by resorption:

not examined

Early or late resorptions:

effects observed, treatment-related

Description (incidence and severity):

A slight test item-related increase in early resorptions was observed at 300 and 1000 mg/kg bw/day, considered adverse (no effect at 100 mg/kg bw/day). No test item effect on late resorptions.

At 1000 mg/kg bw/day:
- Slightly increased mean number of early resorptions (1.2 vs 0.6 in controls), not statistically significant
- Four females had higher number of early resorptions (4, 3, 3, 5)

At 300 mg/kg bw/day:
- Mean number of early resorptions slightly increased (0.9 vs 0.6 in controls), not statistically significant
- Mainly attributed to one animal (all 10 implantations died at a very early stage)
- Possible relation to test item treatment could not be excluded

Dead fetuses:

no effects observed

Changes in pregnancy duration:

not examined

Changes in number of pregnant:

no effects observed

Description (incidence and severity):

No test item-related effect was observed on the number of pregnant females, with the number of females with viable litters equal to 21, 21, 20, 19 in the control, 100, 300 and 1000 mg/kg bw/day groups, respectively.

At scheduled necropsy, four females were non-gravid (1 control, 1 at 300 mg/kg bw/day, 2 at 1000 mg/kg/day). Two females did not survive to scheduled necropsy (1 at 1000 mg/kg bw/day due to early sacrifice on day 20 post-coitum, and 1 at 100 mg/kg bw/day due to early delivery on day 21 post-coitum. One female at 300 mg/kg bw/day had no live foetuses.

Mean numbers of corpora lutea and implantation sites were similar between the treated and control groups, and in the range of normal biological variation.

Other effects:

no effects observed

Effect levels (maternal animals)

1

Key result

Dose descriptor:

NOAEL

Remarks:

general systemic effects

Effect level:

300 mg/kg bw/day (nominal)

Based on:

test mat.

Basis for effect level:

body weight and weight gain

clinical signs

food consumption and compound intake

Remarks on result:

other: Based on clinical signs and decreased body weight / food consumption at 1000 mg/kg bw/day

2

Key result

Dose descriptor:

NOAEL

Remarks:

developmental

Effect level:

100 mg/kg bw/day (nominal)

Based on:

test mat.

Basis for effect level:

pre and post implantation loss

Remarks on result:

other: Based on increased post-implantation loss at 300 and 1000 mg/kg bw/day, used as basis of overall developmental NOAEL

Maternal abnormalities

Key result

Abnormalities:

effects observed, treatment-related

Localisation:

uterus

Description (incidence and severity):

Increased post-implantation loss at 300 and 1000 mg/kg bw/day, used as basis of overall developmental NOAEL

Results (fetuses)

Fetal body weight changes:

effects observed, treatment-related

Description (incidence and severity):

A test item-related decrease in foetal body weight was seen at 1000 mg/kg bw/day, considered adverse. No test item effect at 100 and 300 mg/kg bw/day.

At 1000 mg/kg bw/day:
- Significantly decreased mean foetal body weights compared to controls (males 20.5%, females 21.8%, combined foetal 21.5%)

Reduction in number of live offspring:

no effects observed

Changes in sex ratio:

no effects observed

Description (incidence and severity):

The male : female ratio was unaffected by treatment up to 1000 mg/kg bw/day.

Changes in litter size and weights:

no effects observed

Description (incidence and severity):

There were no test item-related effects on litter size up to 1000 mg/kg bw/day. Litter weight not reported, see foetal weight above.

Mean litter sizes were 11.2, 11.8, 11.1 and 10.3 foetuses/litter for the control, 100, 300, and 1000 mg/kg bw/day groups, respectively. All means remained within the biological variation for rats of this age and strain.

Changes in postnatal survival:

not examined

External malformations:

effects observed, treatment-related

Description (incidence and severity):

Test item-related external malformations occurred at 1000 mg/kg bw/day (considered adverse), but not at 300 or 1000 mg/kg bw/day. No test item-related external variations were noted up to 1000 mg/kg bw/day.

At 1000 mg/kg bw/day (^ considered adverse):
- Three affected foetuses from three litters had cleft palate (with underlying skeletal malformation) ^
- A fourth foetus with a malformation had ectrodactyly and syndactyly of a forepaw, not considered test item-related (chance finding due to the single occurrence)

See summary Tables 3 and 4 below.

Skeletal malformations:

effects observed, treatment-related

Description (incidence and severity):

Test item-related skeletal malformations were observed at 1000 mg/kg bw/day and were considered adverse. The single findings in the control and 300 mg/kg bw/day groups were considered unrelated to treatment. No findings at 100 mg/kg bw/day.

At 1000 mg/kg bw/day (6 foetuses, 6 litters), considered adverse:
- Three foetuses, underlying skeletal malformation (split palatine of an external malformation, cleft palate)
- Three other foetuses, malformations of the thoracic vertebra and/or ribs

At 300 mg/kg bw/day, considered unrelated to treatment:
- One foetus, malformation affecting the thoracic centrum
- Presence of one such malformation in a group is considered a chance finding

See summary Tables 3 and 4 below.

Visceral malformations:

effects observed, non-treatment-related

Description (incidence and severity):

The observed visceral malformations were not considered test item-related.

At 100 and 1000 mg/kg bw/day:
- Two animals had visceral malformations, right-sided aortic arch at 100 mg/kg bw/day and fused liver lobe at 1000 mg/kg bw/day, not considered related to treatment

See summary Tables 3 and 4 below.

Other effects:

effects observed, non-treatment-related

Description (incidence and severity):

ANOGENITAL DISTANCE:
Decreased anogenital distance at 1000 mg/kg bw/day, not considered direct result of test item treatment. No findings at 100 and 300 mg/kg bw/day.

At 1000 mg/kg bw/day:
- Significantly decreased mean anogenital distance for males compared to controls (6.8%)
- Considered secondary to lower foetal weights and not a direct effect of the test item since mean normalized anogenital distance not significantly changed

Effect levels (fetuses)

Key result

Dose descriptor:

NOAEL

Effect level:

300 mg/kg bw/day (nominal)

Based on:

test mat.

Sex:

male/female

Basis for effect level:

fetal/pup body weight changes

external malformations

skeletal malformations

Remarks on result:

other: Based on decreased foetal body weight and increased external and skeletal malformations at 1000 mg/kg bw/day. In the presence of maternal systemic effects.

Fetal abnormalities

Key result

Abnormalities:

effects observed, treatment-related

Localisation:

external: face

external: thorax

skeletal: skull

skeletal: rib

Description (incidence and severity):

Based on external palate and underlying skeletal malformation of the split palatine bone and malformations of the thoracic vertebra and/or ribs at 1000 mg/kg bw/day. These findings were seen in multiple foetuses and multiple litters. In the presence of maternal systemic effects.

Overall developmental toxicity

Key result

Developmental effects observed:

yes

Lowest effective dose / conc.:

300 mg/kg bw/day (nominal)

Treatment related:

yes

Relation to maternal toxicity:

developmental effects in the absence of maternal toxicity effects

Dose response relationship:

yes

Any other information on results incl. tables

Table 2. Summary test item-related microscopic findings – scheduled euthanasia animals

	Females
Dose level (mg/kg bw/day):	0	100	300	1000
THYROID GLANDS^a	21	21	21	21
Follicular cell hypertrophy
Minimal	3	2	4	10

^a = Number of tissues examined from each group

 

Table 3. Number of foetuses examined (litters)

Dose level (mg/kg bw/day)	0	100	300	1000
External examination	236 (21)	248 (21)	222 (20)	195 (19)
Visceral examination	117 (20)	123 (21)	110 (19)	96 (19)
Skeletal examination	119 (21)	125 (21)	112 (20)	99 (19)

 

Table 4. Summary of malformations - individual descriptions

Dose Level (mg/kg bw/day)		Female No.		Foetus No.		Malformation(s) #
0		18		R11		Humerus, Bent (S)
100		33		L6		Aortic arch, Right-sided (V)^a
300		50		R8		Thoracic centrum, 1 or more, Absent (S)^a
1000		71		R9		Palate, Cleft Palate (E) Palatine, Both, Split (S)
		72		R6		Palate, Cleft Palate (E) Palatine, Both, Split (S)
		75		L6		Palate, Cleft Palate (E) Palatine, Both, Split (S)
		76		L2		Forepaw, Ectrodactyly (E)^a Forepaw, Syndactyly (E)^a Liver lobe, Fused (V)^a
		77		L1		Rib, 1 or more, Fused (S) Sternebra, 1 or more, Absent (S) Thoracic arch, 1 or more, Absent (S) Thoracic arch, 1 or more, Fused (S) Thoracic centrum, 1 or more, Absent (S) Thoracic centrum, 1 or more, Fused (S)
		79		R6		Thoracic vertebra, 1 or more, Supernumerary (S)
		80		L2		Thoracic centrum, 1 or more, Absent (S)

#: Including external (E), visceral (V) and skeletal (S) examinations

^a Not considered test item-related

Applicant's summary and conclusion

Conclusions:

In a study conducted according to OECD Test Guideline 414 and in compliance with GLP (reliability score 1), pregnant Wistar Han rats were administered 3-(triethoxysilyl)propanethiol at 0, 100, 300, and 1000 mg/kg bw/day via oral gavage (corn oil vehicle) during days 6 to 20 post-coitum, inclusive. The maternal NOAEL was 300 mg/kg bw/day, based on clinical signs and decreased body weight gain/ food consumption at 1000 mg/kg bw/day. The developmental NOAEL was 100 mg/kg bw/day based on increased percent post-implantation loss at 300 and 1000 mg/kg bw/day. Test item-related decreased foetal body weight and increased external and skeletal malformations were observed only in the presence of maternal systemic effects at 1000 mg/kg bw/day.