Isobutyl laurate

Endpoint summary

Key value for chemical safety assessment

Effects on fertility

Effect on fertility: via oral route

Endpoint conclusion:

no study available

Effect on fertility: via inhalation route

Endpoint conclusion:

no study available

Effect on fertility: via dermal route

Endpoint conclusion:

no study available

Effects on developmental toxicity

Description of key information

Developmental toxicity/teratogenicity (OECD 414, oral), rat: NOAEL (maternal/embryonal) = 1000 mg/kg bw/day (RA CAS 91031-48-0 and RA CAS 22047-49-0)

Link to relevant study records

Reference

Endpoint:

developmental toxicity

Type of information:

migrated information: read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: GLP guideline study with acceptable restrictions (exposure duration was only from day 6-15 of gestation instead of day 5-19).

Qualifier:

according to guideline

Guideline:

OECD Guideline 414 (Prenatal Developmental Toxicity Study)

Version / remarks:

adopted in 1981

Deviations:

no

Qualifier:

according to guideline

Guideline:

OECD Guideline 414 (Prenatal Developmental Toxicity Study)

Version / remarks:

adopted in 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

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

Route of administration:

oral: gavage

Vehicle:

other: Arachidis 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

Remarks:

Doses / Concentrations:
100, 300 and 1000 mg/kg bw/day
Basis:
actual ingested

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

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.

Details on maternal toxic effects:

Maternal toxic effects:no effects

Details on maternal toxic effects:
The dams tolerated the applied dose levels of up to 1000 mg/kg bw/day without lethality and clinical signs of systemic toxicity. Maternal body weight gain was not affected by the treatment.

Mortality:
No death occurred in the dams of group 1 (vehicle control) and in the test groups 2 - 4.

Signs and/or symptoms:
No compound-related symptoms were observed in all treatment groups. In one female (group 3) was noted a skin incrustion on the back and another female (group 1) was severely aggressive by handling.

Body weight gains and corrected body weight:
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.

Reproduction data:
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.

Necropsy findings:
No macroscopic changes were noted in the dams of the groups 1 - 4.

Dose descriptor:

NOAEL

Effect level:

1 000 mg/kg bw/day (nominal)

Based on:

test mat.

Basis for effect level:

other: maternal toxicity

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

Dose descriptor:

NOAEL

Effect level:

1 000 mg/kg bw/day (nominal)

Based on:

test mat.

Basis for effect level:

other: embryotoxicity

Dose descriptor:

NOEL

Effect level:

1 000 mg/kg bw/day (nominal)

Based on:

test mat.

Basis for effect level:

other: teratogenicity

Abnormalities:

not specified

Developmental effects observed:

not specified

Conclusions:

2-ethylhexyl stearate up to a dose of 1000 mg/kg bw/day does not produce any embryo- and fetotoxic or teratogenic effects. The NOAEL for maternal-, developmental-, embryo-, fetotoxicity and teratogenicity is deduced 1000 mg/kg bw/day.

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

Quality of whole database:

The available information comprises adequate, reliable (Klimisch score 2) and consistent studies, from reference substances with similar structure and intrinsic properties. Read-across is justified based on common origin, common precursors and breakdown products of hydrolysis and consistent trends in the toxicological profile. The selected study is thus sufficient to fulfil the standard information requirements set out in Annex VIII-IX, 8.7, in accordance with Annex XI, 1.5, of Regulation (EC) No 1907/2006.

Effect on developmental toxicity: via inhalation route

Endpoint conclusion:

no study available

Effect on developmental toxicity: via dermal route

Endpoint conclusion:

no study available

Additional information

Justification for grouping of substances and read-across

There are only limited data available on toxicity to reproduction of isobutyl laurate (CAS 37811-72-6). In order to fulfil the standard information requirements set out in Annex VIII, 8.7, in accordance with Annex XI, 1.5, of Regulation (EC) No 1907/2006, read-across from structurally related substances was conducted. In accordance with Article 13 (1) of Regulation (EC) No 1907/2006, "information on intrinsic properties of substances may be generated by means other than tests, provided that the conditions set out in Annex XI are met.” In particular for human toxicity, information shall be generated whenever possible by means other than vertebrate animal tests, which includes the use of information from structurally related substances (grouping or read-across). Having regard to the general rules for grouping of substances and read-across approach laid down in Annex XI, Item 1.5, of Regulation (EC) No 1907/2006 whereby substances may be predicted as similar provided that their physicochemical, toxicological and ecotoxicological properties are likely to be similar or follow a regular pattern as a result of structural similarity.

Overview of toxicity to reproduction

CAS	Chemical name	Molecular weight [g/mol]	Toxicity to reproduction	Developmental toxicity/teratogenicity
37811-72-6 (a)	Isobutyl laurate	256.42	--	RA: CAS 91031-48-0 RA: CAS 22047-49-0
91031-48-0 (b)	Fatty acids, C16-18, 2-ethylhexyl esters	368.65-396.7	--	Experimental result: NOAEL (maternal/embryonal) =1000 mg/kg bw/day (rat)
22047-49-0 (b)	2-ethyl hexyl stearate	396.7	--	Experimental result: NOAEL (maternal/embryonal) =1000 mg/kg bw/day (rat)

(a) The substance subject to registration is indicated in bold font.

(b) Reference (read-across) substances are indicated in normal font. Lack of data for a given endpoint is indicated by “--“.

The above mentioned substance is considered to be similar on the basis of the structural similar properties and/or activities. The available endpoint information is used to predict the same endpoints for isobutyl laurate (CAS 37811-72-6). A detailed analogue approach justification is provided in the technical dossier (see IUCLID Section 13).

 

Discussion

No data on toxicity to reproduction is available with isobutyl laurate (CAS 37811-72-6). Therefore, read across from the structurally analogue substances fatty acids, C16-18, 2-ethylhexyl esters (CAS 91031-48-0) and 2-ethyl hexyl stearate (CAS 22047-49-0) was applied.

Toxicity to reproduction (fertility)

According to Regulation (EC) No 1907/2006, Annex VIII, 8.7.1., column 2, a screening test for toxicity to reproduction is not required as two tests for prenatal developmental toxicity (Annex IX, 8.7.2) are available for the structural related substances Fatty acids, C16-18, 2-ethylhexyl esters (CAS 91031-48-0) and 2-ethylhexyl stearate (CAS 22047-49-0), which will be used for read-across. On the basis of these prenatal developmental toxicity studies no test item related toxicological findings in dams or fetuses were revealed.

 

Developmental toxicity/teratogenicity

CAS 91031-48-0

A Prenatal Developmental Toxicity Study was performed with fatty acids, C16-18, 2-ethylhexyl esters (CAS 91031-48-0) according to OECD TG 414 (Pittermann, 1994). Groups of 24 female Sprague-Dawley rats received daily oral gavage doses of the test substance in arachis oil at dose levels of 0, 100, 300 and 1000 mg/kg bw/day during gestational days 6 to 15. On day 20 of gestation the animals were euthanized and examined for maternal and fetal parameters. Based on the number of implantations, number of total litter losses by resorption, mortality, clinical signs, body weight, gross pathology and organ weights of maternal animals the NOAEL for maternal toxicity was found to be 1000 mg/kg bw/day. Examination of fetus litter size and weights, offspring viability (number alive and number dead), sex ratio, grossly visible abnormalities, external, head, soft tissue and skeletal abnormalities showed no differences to control and no indication for teratogenic effects. Therefore, the NOAEL for embryo-/fetotoxicity and teratogenicity in rats for fatty acids C16-18, 2-ethylhexyl esters was found to be 1000 mg/kg bw/day.

 

CAS 22047-49-0

The developmental toxicity of 2-ethylhexyl stearate (CAS 22047-49-0) was investigated according to OECD TG 414 and GLP conditions (Aulmann, 2000). Groups of 24 female Sprague-Dawley rats received daily oral gavage doses of the test substance in arachis oil at dose levels of 0, 100, 300 and 1000 mg/kg bw/d during gestational days 6 to 15. On day 20 of gestation the animals were euthanized and examined for maternal and fetal parameters. Based on the number of implantations, number of total litter losses by resorption, mortality, clinical signs, body weight, gross pathology and organ weights of maternal animals the NOAEL for maternal toxicity was found to be 1000 mg/kg bw/d. Examination of fetus litter size and weights, offspring viability (number alive and number dead), sex ratio, grossly visible abnormalities, external, head, soft tissue and skeletal abnormalities showed no differences to control and no indication for teratogenic effects. Therefore, the NOAEL for embryo-/fetotoxicity and teratogenicity in rats for 2-ethylhexyl stearate was found to be 1000 mg/kg bw/day.

 

Taken together, the available data on toxicity to reproduction from structural analogue substances do not indicate any toxicological adverse effect on maternal and embryonal toxicity. Therefore, according to EU classification criteria, the target substance isobutyl laurate (CAS 37811-72-6) is not to be classified.

Justification for selection of Effect on developmental toxicity: via oral route:
Hazard assessment is conducted by means of read-across from structural analogues. The selected study is the most adequate and reliable study based on the identified similarities in structure and intrinsic properties between source and target substance and overall assessment of quality, duration and dose.

References:

A detailed reference list is provided in the technical dossier (see IUCLID, section 13) and within the CSR.

Justification for classification or non-classification

According to Article 13 of Regulation (EC) No. 1907/2006 "General Requirements for Generation of Information on Intrinsic Properties of substances", information on intrinsic properties of substances may be generated by means other than tests e.g. from information from structurally related substances (grouping or read-across), provided that conditions set out in Annex XI are met. Annex XI, "General rules for adaptation of this standard testing regime set out in Annexes VII to X” states that “substances whose physicochemical, toxicological and ecotoxicological properties are likely to be similar or follow a regular pattern as a result of structural similarity may be considered as a group, or ‘category’ of substances. This avoids the need to test every substance for every endpoint". Since the analogue concept is applied to isobutyl laurate (CAS 37811-72-6), data will be generated from data for reference source substance(s) to avoid unnecessary animal testing. Additionally, once the analogue read-across concept is applied, substances will be classified and labelled on this basis.

Therefore, based on the analogue read-across approach, the available data on toxicity to reproduction do not meet the classification criteria according to Regulation (EC) 1272/2008, and are therefore conclusive but not sufficient for classification.