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Toxicity to reproduction: other studies

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Endpoint:
toxicity to reproduction: other studies
Type of information:
experimental study
Adequacy of study:
supporting study
Study period:
26 September 2019 to 05 November 2019
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
test procedure in accordance with generally accepted scientific standards and described in sufficient detail
Justification for type of information:
Study conducted to streghthen the pre-developmental study in a read-across approach: see section 7.8.2
Cross-reference
Reason / purpose for cross-reference:
reference to same study
Reference
Endpoint:
developmental toxicity
Type of information:
read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
key study
Justification for type of information:
See the RAAF Document.
Reason / purpose for cross-reference:
read-across source
Clinical signs:
effects observed, treatment-related
Description (incidence and severity):
- At 1000 mg/kg bw/day: mild decrease in locomotor activity in 12 of 25 animals, loose stool in 24, and soiled lower abdomen due to urine in 23 animals, on and after gestation day 7 (2 days after the start of administration); and transient mild salivation immediately after administration, on and after gestation day 6 (1 day after the start of administration). The decreased locomotor activity resolved around 4 hours after administration.
- At 60 and 250 mg/kg bw/day: no changes in clinical signs were observed (See Attached Table 7.8.2.2).
Mortality:
no mortality observed
Description (incidence):
No death was observed in any of the groups (See Attached Table 7.8.2.2).
Body weight and weight changes:
effects observed, treatment-related
Description (incidence and severity):
- At 1000 mg/kg bw/day: decreased weight gain was observed during the gestation period. A significant decrease was observed in body weight from gestation day 9 through 20 and in body weight gain during the administration period.
- At 60 and 250 mg/kg bw/day: no significant changes were observed.
- No test substance-related effects on mean body weights, body weight gains, net body weight gains or gravid uterine weights were observed (See Attached Table 7.8.2.3).
Food consumption and compound intake (if feeding study):
effects observed, treatment-related
Description (incidence and severity):
- At 1000 mg/kg bw/day: a significant decrease in food consumption was observed from gestation day 6 through 20.
- Animals in 60 and 250 mg/kg bw/day groups did not show any significant change (See Attached Table 7.8.2.4).
Food efficiency:
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:
effects observed, treatment-related
Description (incidence and severity):
- Animals in 1000 mg/kg bw/day group showed a significant decrease in placental weight but did not show any significant change in other test parameters.
- Animals in 60 and 250 mg/kg bw/day groups did not show any significant change in uterine weight, or placental weight.
Gross pathological findings:
effects observed, treatment-related
Description (incidence and severity):
- Necropsy revealed mild thickening of forestomach in 23 of 25 animals in 1000 mg/kg bw/day group. Mother animals in the control group, 60 mg/kg bw/day group, and 250 mg/kg bw/day group did not show gross abnormalities in the visceral organs, showing no abnormalities in the uterus, such as amniotic fluid, either (See Attached Table 7.8.2.5).
Neuropathological findings:
not examined
Histopathological findings: non-neoplastic:
not examined
Histopathological findings: neoplastic:
not examined
Number of abortions:
no effects observed
Description (incidence and severity):
See Attached Table 7.8.2.6.
Pre- and post-implantation loss:
no effects observed
Description (incidence and severity):
See Attached Table 7.8.2.6.
Total litter losses by resorption:
no effects observed
Description (incidence and severity):
See Attached Table 7.8.2.6.
Early or late resorptions:
no effects observed
Description (incidence and severity):
See Attached Table 7.8.2.6.
Dead fetuses:
no effects observed
Description (incidence and severity):
See Attached Table 7.8.2.6.
Changes in pregnancy duration:
no effects observed
Description (incidence and severity):
See Attached Table 7.8.2.6.
Changes in number of pregnant:
effects observed, treatment-related
Description (incidence and severity):
The number of pregnant animals was 23 in the control group, 25 in 60 mg/kg bw/day group, 24 in 250 mg/kg bw/day group, and 25 in 1000 mg/kg bw/day group (See Attached Table 7.8.2.6).
Dose descriptor:
NOAEL
Effect level:
1 000 mg/kg bw/day (actual dose received)
Based on:
test mat.
Basis for effect level:
other: maternal toxicity
Remarks on result:
other: Clinical signs, decreased body weight gain and food consumption observed at 1000 mg/kg bw/day with Alkyl Ether Carboxylate.
Key result
Dose descriptor:
NOAEL
Effect level:
ca. 2 400 mg/kg bw/day
Based on:
other: Trideceth-2 Carboxamide MEA
Basis for effect level:
other: maternal toxicity
Remarks on result:
other: decreased body weight gain and food consumption observed at 1000 mg/kg bw/day
Abnormalities:
not specified
Fetal body weight changes:
no effects observed
Description (incidence and severity):
No significant changes were observed in body weight of live fetuses in any of the test substance groups (See Attached Table 7.8.2.6).
Reduction in number of live offspring:
no effects observed
Description (incidence and severity):
No significant changes were observed in the number of live fetuses in any of the test substance groups (See Attached Table 7.8.2.6).
Changes in sex ratio:
no effects observed
Description (incidence and severity):
No significant changes were observed in the sex ratio in any of the test substance groups (See Attached Table 7.8.2.6).
Changes in litter size and weights:
no effects observed
Description (incidence and severity):
No significant changes were observed in any of the test substance groups (See Attached Table 7.8.2.6).
Changes in postnatal survival:
no effects observed
External malformations:
effects observed, non-treatment-related
Description (incidence and severity):
- External examination including oral examination was conducted in 324 animals in the control group, 375 in 60 mg/kg bw/day group, 359 in 250 mg/kg bw/day group, and 360 in 1000 mg/kg bw/day group. Dwarf fetuses were observed as follows: 3 (incidence 0.9%) in the control group, 2 (0.7 %) in 60 mg/kg group, 3 (0.8 %) in 250 mg/kg bw/day group, and 1 (0.3 %) in 1000 mg/kg bw/day group. One (0.3%) each of cleft-lip fetus and tail-less fetus was observed in 1000 mg/kg bw/day group.
- There was no significant difference between the control group and each test substance group in the incidence of fetuses with external abnormality or in the incidence of each type of external abnormality (See Attached Table 7.8.2.7).
Skeletal malformations:
effects observed, non-treatment-related
Description (incidence and severity):
There was no significant difference between the control group and each test substance group in the incidence of skeletal variations (See Attached Table 7.8.2.8) .
Skeletal examination was conducted in 160 fetuses in the control group, 186 in 60 mg/kg bw/day group, 172 in 250 mg/kg bw/day group, and 193 in 1000 mg/kg bw/day group.
- Skeletal anomalies observed were fused cervical vertebral arch and fused thoracic vertebral arch in 1 fetus each, 2 in total (incidence 1.0%) in the control group. In the test substance groups, the only skeletal anomaly observed was partially missing sacral vertebral bones in 1 fetus (0.5%) in 1000 mg/kg bw/day group.
- The following skeletal variations were observed in each group: Cervical rib (incidence 0-3.4%), asymmetric sternebrae (0-0.5%), dumbbell-shaped thoracic vertebral body (1.7-5.2%), split of the thoracic vertebral body (0.3-2.3%), short thoracic vertebral arch (0-0.5%), small thoracic vertebral body (0-1.0%), short 13th rib (0-1.6%), 14th rib (0-0.6%), lumbar rib (4.5-9.8%), dumbbell-shaped lumbar vertebral body (0-0.5%), sacralization of lumbar vertebral arch (0-0.5%), variation of the number of lumbar spinal bones (0-0.5%), split of the lumbar vertebral body (0-0.5%), small lumbar vertebral body (0-0.5%), and lumbar vertebral deformity (0-0.5%).
- The number of fetuses with any of these skeletal variations (incidence) was 21 (13.8 %) in the control group, 27 (13.7 %) in 60 mg/kg bw/day group, 16 (8.9 %) in 250 mg/kg bw/day group, and 31 (17.5 %) in 1000 mg/kg bw/day group, with the incidence showing no significant difference between the control group and each test substance group or no tendency of dose-dependent increase. The incidence of each type of skeletal variation did not show any significant difference between the control group and each test substance group, nor did it show any tendency of dose-dependent increase.
- As for ossification, all parameters including the numbers of ossified sternebral bones, caudal vertebral bones, metacarpal bones, and metatarsal bones were comparable between the control group and each test substance group, showing no significant changes. In 250 mg/kg bw/day group, one fetus (incidence 0.5%) showed delayed ossification of cervical vertebral arch and 3 fetuses (1.4%) showed delayed ossification of ischial bones, but none of them were significant.
Visceral malformations:
no effects observed
Description (incidence and severity):
Visceral examination was conducted on 164 fetuses in the control group, 189 in 60 mg/kg bw/day group, 187 in 250 mg/kg bw/day group, and 167 in 1000 mg/kg bw/day group (See Table 7.8.2.9)
- No fetuses with visceral anomalies were observed either in the control group or in the test substance groups.
- Visceral variations observed were thymic cervical residue (incidence 0.5%-1.3%) in all treatment groups and persistent left umbilical artery (1.7%) in 1000 mg/kg bw/day group.
- The number of fetuses with either of these visceral variations (incidence) was 2 (1.1%) in the control group, 2 (1.2%) in 60 mg/kg bw/day group, 3 (1.3%) in 250 mg/kg bw/day group, and 3 (2.1%) in 1000 mg/kg bw/day group, with no significant difference in the incidence between the control group and each test substance group. Also, no significant difference was observed in the incidence of each type of visceral variation between the control group and each test substance group.
Other effects:
no effects observed
Dose descriptor:
NOAEL
Effect level:
>= 1 000 mg/kg bw/day (nominal)
Based on:
test mat.
Sex:
male/female
Basis for effect level:
other: No effects were observed.
Key result
Dose descriptor:
NOAEL
Effect level:
ca. 2 400 mg/kg bw/day
Based on:
other: Trideceth-2 Carboxamide MEA
Sex:
male/female
Basis for effect level:
other: No effects were observed.
Abnormalities:
not specified
Developmental effects observed:
not specified

none

Conclusions:
Under the test conditions, the NOAEL for maternal toxicity (systemic effects) and the NOAEL for developmental toxicity were set to 1000 mg/kg bw/d, which corresponds to 2400 mg/kg bw/day of the registered substance.
Executive summary:

In a developmental toxicity study conducted according to the OECD guideline No. 414 and in compliance with GLP, the test substance diluted in deionized water was administered to 25 females SD [Crl: CD (SD)] rats/dose by gavage at dose levels of 0, 60, 250 or 1000 mg/kg bw/day from days 6 through 19 of gestation (dose volume = 10 mL/kg bw).

 

All animals were observed twice daily for appearance and behavior. Clinical observations, bodyweight and food consumption were recorded at appropriate intervals. On gestation day 20, a laparohysterectomy was performed on each female. The uteri and ovaries were examined, and the number of fetuses, early and late resorptions, total implantations and corpora lutea were recorded. Gravid uterine weights were recorded, and net body weights and net body weight changes were calculated. The fetuses were weighted, sexed and examined for external, visceral and skeletal malformations and developmental variation.

 

All animals survived to the scheduled necropsy on GD20. Animals at 1000 mg/kg bw/day showed changes in clinical signs including decreased locomotor activity, loose stool, soiled lower abdomen due to urine, and transient salivation immediately after administration, as well as decreased weight gain, decreased food consumption, thickening of forestomach, and decreased placental weight. No effects were observed in 60 and 250 mg/kg bw/day groups.

There were no test article-related internal findings at the scheduled necropsy. For the effect on fetuses, no significant changes were observed in the number of live fetuses, embryo/fetal mortality, sex ratio, body weight of live fetuses, or in the external, visceral, or skeletal examination of fetuses, at all tested animals. No test article-related fetal malformations or developmental variations were noted at any dose level in this study. No other signs of developmental toxicity were noted.

Based on the results of this study the dose level of 1000 mg/kg bw/day was considered to the NOAEL maternal toxicity (systemic effects) and developmental toxicity, which corresponds to 2400 mg/kg bw/d of the registered substance.
Under the test conditions, the registered substance is not classified according to Regulation (EC) No.1272/2008 (CLP) criteria.

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2019

Materials and methods

Results and discussion

Applicant's summary and conclusion

Conclusions:
Under the test conditions, the dTP (o/c ratio) is 13.3 µg/mL and toxicity potential (TP, cell viability) is 13.4 µg/mL. The test article elicited a biphasic response in the o/c ratio due to increased cystine uptake prior to cell death, which may be an adaptive response to oxidative stress, followed by cell death when the cells cannot overcome the stress. However, the test article caused metabolic perturbation at concentrations similar to those that impacted cell viability. Therefore, it can be concluded that the metabolic disturbance was a consequence of cytotoxicity and that there is no evidence for any potential for developmental toxicity. and that there is no evidence for any potential for developmental toxicity.
Executive summary:

The purpose of this study was to predict a test article developmental toxicity potential. The impact of test article exposure on ornithine and cystine metabolism in human induced pluripotent stem (iPS) cells was measured for the test article and prediction of the potential for developmental toxicity was made through application of the hPS cell-based devTOXquickPredict assay. Exposure spanned a range of eight treatment levels ( 0.03 - 100 µg/mL)


The dTP (o/c ratio) is 13.3 µg/mL and toxicity potential (TP, cell viability) is 13.4 µg/mL. The test article elicited a biphasic response in the o/c ratio due to increased cystine uptake prior to cell death, which may be an adaptative response to oxidative stress, followed by cell death when the cells cannot overcome the stress. The test article caused metabolic perturbation at concentrations similar to those that impacted cell viability. Human iPS cell viability was decreased by the test article at concentrations similar to those that were cytotoxic in mouse lymphoma L5178Y cells in the absence of S9 after after 24 hours of exposure (31.3 µg/mL). Therefore, it can be concluded that the metabolic disturbance was a consequence of cytotoxicity and that there is no evidence for any potential for developmental toxicity.

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