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Toxicological information

Developmental toxicity / teratogenicity

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Administrative data

Endpoint:
developmental toxicity
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
guideline study with acceptable restrictions
Remarks:
(exposure duration was only from day 6-15 of gestation instead of day 5-19).

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
1994
Report date:
1994

Materials and methods

Test guidelineopen allclose all
Qualifier:
according to guideline
Guideline:
OECD Guideline 414 (Prenatal Developmental Toxicity Study)
Version / remarks:
1981
Deviations:
no
Qualifier:
equivalent or similar to guideline
Guideline:
OECD Guideline 414 (Prenatal Developmental Toxicity Study)
Version / remarks:
2001
Deviations:
yes
Remarks:
Exposure duration was only from day 6-15 of gestation instead of day 5-19.
GLP compliance:
yes
Limit test:
no

Test material

Constituent 1
Chemical structure
Reference substance name:
Fatty acids, C16-18, 2-ethylhexyl esters
EC Number:
292-951-5
EC Name:
Fatty acids, C16-18, 2-ethylhexyl esters
Cas Number:
91031-48-0
Molecular formula:
C24H48O2 to C26H52O2
Test material form:
liquid

Test animals

Species:
rat
Strain:
Sprague-Dawley
Details on test animals or test system and environmental conditions:
TEST ANIMALS
- Source: Charles River Wiga, Sulzfeld, Germany
- Age at study initiation: approx. 8-10 weeks
- Weight at study initiation: mean approx. 197 g
- Housing: individually in Makrolon Type M3 cages (Ebeco) with standard softwood bedding (ARWI-Center, Essen, Germany)
- Diet: Pelleted Altromin Maintenance Diet 1324, Lot No. 221092/1558 (Altromin GmbH, Lage, Germany), ad libitum
- Water: tap water, ad libitum
- Acclimation period: 5 days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 21-23
- Humidity (%): 40-56
- Air changes (per hr): 10-15 per hr
- Photoperiod (hrs dark / hrs light): 12/12

Administration / exposure

Route of administration:
oral: gavage
Vehicle:
other: Arachis oil, DAB 10
Details on exposure:
PREPARATION OF DOSING SOLUTIONS:
The dosing solutions were prepared daily before administration.

VEHICLE
- Justification for use and choice of vehicle (if other than water): solubility of test substance
- Concentration in vehicle: 20, 60 and 200 mg/mL, respectively for the 100, 300 and 1000 mg/kg bw dose groups
- Amount of vehicle (if gavage): 5 mL/kg bw

After arrival all females were assigned to the different groups using a computer-generated random algorithm.

Analytical verification of doses or concentrations:
no
Details on mating procedure:
- Impregnation procedure: purchased timed pregnant, at day 0
- Proof of pregnancy: vaginal plug day 0 of pregnancy
Duration of treatment / exposure:
from day 6 up to day 15 of gestation
Frequency of treatment:
once daily
Duration of test:
until day 20 of gestation
Doses / concentrationsopen allclose all
Dose / conc.:
100 mg/kg bw/day (actual dose received)
Dose / conc.:
300 mg/kg bw/day (actual dose received)
Dose / conc.:
1 000 mg/kg bw/day (actual dose received)
No. of animals per sex per dose:
24 females per dose
Control animals:
yes, concurrent vehicle
Details on study design:
- Other:
group 1: 0 mg/kg bw/day
group 2: 100 mg/kg bw/day
group 3: 300 mg/kg bw/day
group 4: 1000 mg/kg bw/day

Examinations

Maternal examinations:
CAGE SIDE OBSERVATIONS: Yes
- Time schedule: daily
Mortality rate: The animals were checked at least twice daily for any mortality.
Signs and/or symptoms: The animals were observed at least twice daily (working days) for signs of reaction to treatment and/or symptoms of illness.

POST-MORTEM EXAMINATIONS: Yes
- Sacrifice on gestation day 20
- Organs examined: Post mortem examination, including gross macroscopic examination of all maternal organs, with emphasis on the uterus, uterine contents, position of fetuses in the uterus and number of corpora lutea, was performed and the data recorded.
The uteri (including content) of all females were weighed at necropsy on day 20 post coitum to enable the calculation of the corrected body weight gain.
- Any female sacrificed or found dead during the study was subjected to macroscopic examination of the visceral organs, with emphasis on the uterus and its content.

BODY WEIGHT: Yes, mean body weight changes
- Time schedule for examinations: days 0, 6, 16 and 20 of gestation
Ovaries and uterine content:
The ovaries and uterine content was 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

Number and distribution of intrauterine implantations were classified as live or death fetuses, late intrauterine deaths (resorptions), early intrauterine (resorption sites). The fetuses were removed from the uterus. Intrauterine deaths were classified on the basis of the presence (late) or absence (early) of fetal or decidual tissue in addition to placental tissue.
Fetal examinations:
- External examinations: Yes: half per litter
- Soft tissue examinations: Yes: half per litter: malformations oh hydrocephalus, variations of brain, adrenal gland, renal pelvis, ureter
- Skeletal examinations: Yes: half per litter: malformations of hydrops, retardations of skull bones, hyoid, sternebrae, pelvis, 13th rib
- Head examinations: Yes: half per litter

The live fetuses were sexed, weighed individually including placentae, examined for gross external abnormalities and allocated to one of the following procedures:
1) Half of the fetuses from each litter was non individually fixed in Bouin's solution in order to examine viscera and brain by Wilson's slicing technique. After examination the sections were not preserved.
2) The remaining fetuses were placed non individually in a solution of potassium hydroxide for clearing and were stained with alizarin red (Shandon Varistain 24-T). The skeletons were examined and preserved in plastic containers. All abnormalities were recorded.
Statistics:
The following statistical methods were used:
If the variables could be assumed to follow a normal distribution, the Dunnett-Test, based on a pooled variance, was applied for the comparison between the treated groups and the control group, otherwise the Steel-Test was applied.
Fisher's Exact test for 2x2 tables was applied if the variables could be dichotomized without loss of information (Bonferroni-Holm-corrected).
Historical control data:
Findings both on the individual foetus and on the litter basis did not differ from the available historical control obtained in six developmental toxicity studies on the same species.

Results and discussion

Results: maternal animals

General toxicity (maternal animals)

Clinical signs:
no effects observed
Description (incidence and severity):
The dams tolerated the applied dose levels of up to 1000 mg/kg bw/day without lethality and clinical signs of systemic toxicity. In one female (group 3) was noted a skin incrustation on the back and another female (group 1) was severely aggressive by handling. These were incidental observations without relation to treatment.
Mortality:
no mortality observed
Description (incidence):
The dams tolerated the applied dose levels of up to 1000 mg/kg bw/day without lethality and clinical signs of systemic toxicity.
Body weight and weight changes:
no effects observed
Description (incidence and severity):
Body weight profiles of the pregnant females were essentially similar in all groups. Mean corrected body weight gain of the treatment groups compared favourably with the control values.
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:
not examined
Gross pathological findings:
no effects observed
Description (incidence and severity):
No macroscopic changes were noted in the dams of all groups.
Neuropathological findings:
not examined
Histopathological findings: non-neoplastic:
not examined
Histopathological findings: neoplastic:
not examined

Maternal developmental toxicity

Number of abortions:
no effects observed
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:
no effects observed
Changes in number of pregnant:
no effects observed
Description (incidence and severity):
No compound-related differences were noted between the mean reproduction data of the test groups in comparison to the control group. In the group 2 and 4 the post-implantation loss and total embryonic deaths were significantly decreased. These findings were considered to be incidental because of the high control values. Furthermore the number of total fetuses was increased in the group 2 and 4, which is also incidental because there was no dose-relationship.

Effect levels (maternal animals)

Key result
Dose descriptor:
NOAEL
Effect level:
>= 1 000 mg/kg bw/day (nominal)
Based on:
test mat.
Basis for effect level:
other: maternal toxicity

Maternal abnormalities

Key result
Abnormalities:
no effects observed

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
External malformations:
no effects observed
Skeletal malformations:
no effects observed
Visceral malformations:
no effects observed
Details on embryotoxic / teratogenic effects:
Embryotoxic / teratogenic effects:no effects

Details on embryotoxic / teratogenic effects:
Apart from dose group 1000 mg/kg bw/day (one dead foetus) all females had viable foetuses. Pre- and postimplantation loss and mean numbers of resorption were unaffected by treatment. All parameters were comparable with the animals of the control group. Skeletal and visceral investigations detected no treatment-related malformations.

Body weight:
The weights of live fetuses exibited no significant differences on a litter and individual basis e.g. mean weight between the control group and the treatment groups.

Placenta and uterus weight:
The weights of placentae and the whole uterus showed no significant differences between the control group and the treatment groups.

Sex ratios:
The sex ratio of the fetuses was not effected by the treatment with the test substance.

External examinations:
No substance-related macroscopical findings were noted at external examination of fetuses which were considered to be an effect of the treatment with the test article. In the group 1 was noted a beginning hydrops and in the group 4 one fetus with paleness and one dead fetus.

Visceral examination:
The findings were as follows:
Group 1: 127 examined fetuses
28 hydronephrosis
9 ureter dilatation
5 ureter waved
1 runt, brain lateral sinus dilatation, other organs normal
1 thorax - blood coagulum [artifact]
1 adrenal central pinhead cyst [suspicious]
1 umbilical region - gut protrusion [artifact]

Group 2: 138 examined fetuses
34 hydronephrosis
12 ureter dilatation
3 ureter waved
1 runt, hydrocephalus internus

Group 3: 138 examined fetuses
26 hydronephrosis
5 ureter dilatation
6 ureter waved
1 ear region subcutaneous hematoma
1 umbilical region - gut protrusion [artifact]

Group 4: 140 examined fetuses
24 hydronephrosis
10 ureter dilatation
8 ureter waved
1 inguinal hernia, protrusion of gut and testis between peritoneum and trunk, muscles [artifact]
1 runt, brain lateral sinus dilatation, other organs normal

The visceral examination of the preserved fetuses did not reveal any treatment-related abnormalities.

Skeletal examination of fetuses:
Retardations:
Group 1: 141 examined fetuses
Group 2: 152 examined fetuses
single sternebrae non ossified,
significant increase at level 1% (34 fetuses out of 22 dams)
Group 3: 150 examined fetuses: no significant findings
Group 4: 152 examined fetuses
single sternebrae non ossified,
significant increase at level 5 % (29 fetuses out of 22 dams)
two sternebrae non ossified,
significant increase at level 1 % (21 fetuses out of 22 dams)

The statistically significant differences were considered to be incidental because these retardation effects were not accompanied by weight retardation of the treatment groups. The incidental character of these retardations is emphasized by the fact the values were within the normal range of variation for this strain.

Variations (examined fetuses):
Group 1: no variations
Group 2: no variations
Group 3: no variations
Group 4: no variations

Malformations (examined fetuses):
Group 1: 1 fetus beginning hydrops
Group 2: no findings
Group 3: no findings
Group 4: no findings


Effect levels (fetuses)

Key result
Dose descriptor:
NOAEL
Effect level:
>= 1 000 mg/kg bw/day (nominal)
Based on:
test mat.
Sex:
male/female
Basis for effect level:
other: embryotoxicity

Fetal abnormalities

Key result
Abnormalities:
no effects observed

Overall developmental toxicity

Key result
Developmental effects observed:
no

Applicant's summary and conclusion

Conclusions:
Fatty acids, C16-18, 2-ethylhexyl esters up to a dose of 1000 mg/kg bw/day does not produce any embryo- and foetotoxic or teratogenic effects. The NOAEL for maternal-, developmental-, embryo-, foetotoxicity and teratogenicity is deduced 1000 mg/kg bw/day.

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