Fatty acids, C18-unsatd., dimers, 2-ethylhexyl esters

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

Additional information

Justification for grouping of substances and read-across

There are no data available the toxicity to reproduction of Fatty acids, C18-unsatd., dimers, 2-ethylhexyl esters (CAS 68334-05-4). In order to fulfil the standard information requirements set out in Annex X, 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 and/or common chemical precursors or similar hydrolysis/breakdown products (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 and/or common chemical precursors or similar hydrolysis/breakdown products.

The read-across is either based structural similarity or on the metabolism of Fatty acids, C18-unsatd., dimers, 2-ethylhexyl esters (CAS 68334-05-4), in particular on the fact that the substance undergoes enzymatic ester hydrolysis resulting in the formation of Fatty acids, C18-unsatd., dimers and 2-ethylhexanol. A detailed analogue approach justification is provided in the technical dossier (see IUCLID Section 13).

Overview of reproductive toxicity

CAS	Chemical name	Molecular weight	Toxicity to reproduction – Fertility	Toxicity to reproduction – Developmental Toxicity
68334-05-4 (a)	Fatty acids, C18-unsatd., dimers, 2-ethylhexyl esters	673.12	waiving	RA: CAS 104-76-7: equimolar NAEL = 987 mg/kg bw/day
104-76-7 (b)	2-ethylhexanol	130.23	--	Experimental result: NOAEL = 191 mg/kg bw/day

(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 substances are considered to be similar on the basis of common chemical precursors and common hydrolysis/breakdown products. The available endpoint information is used to predict the same endpoints for Fatty acids, C18-unsatd., dimers, 2-ethylhexyl esters (CAS 68334-05-4). A detailed analogue approach justification is provided in the technical dossier (see IUCLID Section 13).

 

Discussion

Toxicity to reproduction – fertility

No studies on toxicity to reproduction (fertility) were available with fatty acids, C18 unsatd. Dimers, 2 -ethylhexyl esters. However, data on the oral repeated dose toxicity of the hydrolysis product 2-Ethylhexanol (CAS 104-76-7) and Fatty acids, C18-unsatd., dimers (61788-89-4) demonstrate no adverse effects on reproduction organs and tissues after subchronic exposure up to and including the highest dose tested. Therefore, based on the weight of evidence, a reproduction toxicity study by any route of exposure is considered scientifically unjustified and not necessary in terms of animal welfare.

In summary, the available data provide sufficient evidence to conclude that the substance of Fatty acids, C18 unsatd. dimers, 2 -ethylhexyl esters is not toxic to reproduction.

Effects on fertility:

A waiver for the requirement to perform an extended one-generation reproduction toxicity study (standard configuration or with additional modules) was included, as the study is not scientifically necessary and, considering concerns regarding the use of vertebrate animals for experimental purposes, unjustified.

Short description of key information:
No one- or more-generation reproduction toxicity studies were available. However, no indications for reprotoxic effects could be observed in subchronic (90d) repeated dose toxicity studies performed with the RA substances 2-ethylhexanol (CAS 104-76-6) and Fatty acids, C18-unsatd., dimers, hydrogenated (CAS 61788-89-4).

Effects on developmental toxicity

Description of key information

A developmental and maternal NOAEL for 2-ethylhexanol (CAS No. 104-76-7) of 191 mg/kg bw/d was found in mice (Tyl, 1991, NTP).
This corresponds to an equimolar developmental NAEL for fatty acids, C18 unsatd. dimers, 2 ethylhexyl esters of 987.35 mg/kg bw/d. 

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

Study period:

1990-05-18 to 1990-08-22

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: see 'Remark'

Remarks:

GLP - Guideline study, tested with the source substance 2-EH (CAS No. 104-76-7). In accordance to the ECHA guidance document “Practical guide 6: How to report read-across and categories (March 2010)”, the reliability was changed from RL1 to RL2 to reflect the fact that this study was conducted on a read-across substance.

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 414 (Prenatal Developmental Toxicity Study)

Deviations:

no

GLP compliance:

not specified

Limit test:

no

Species:

mouse

Strain:

CD-1

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Charles River Laboratories, Inc., Raleigh, NC
- Weight at study initiation: 23.52-31.59 g
- Housing: Plug-positive females were individually housed in solid-bottom polycarbonate cages with stainless steel wire lids (Laboratory Products, Rochelle Park, NJ) and Ab-Sorb-Dri® cage litter (Laboratory Products, Garfield, NJ
- Diet (e.g. ad libitum): Ground Purina Certified Rodent ChoW® (#5002) available ad libitum throughout gestation
- Water (e.g. ad libitum): deionized/filtered water were available ad libitum throughout gestation
- Acclimation period: 7 days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 22.2
- Humidity (%): 48
- Photoperiod (hrs dark / hrs light): 12/12

Route of administration:

oral: feed

Vehicle:

other: food grade modified corn starch microcapsules

Details on exposure:

PREPARATION OF DOSING SOLUTIONS:

DIET PREPARATION
- Rate of preparation of diet (frequency): Fresh supplies of dosed feed were obtained from refrigerated stock on the mornings of gd 0, 3, 6, 9, 12 and 15

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

Analysis by gas chromatography (GC) prior to use verified the formulations to be within 99-108% of the theoretical concentrations. 2EH/feed mixes were determined to be stable throughout the period of use for each study replicate.

Details on mating procedure:

- Impregnation procedure: cohoused
- M/F ratio per cage:1/1
- Length of cohabitation: overnight
- Proof of pregnancy: vaginal plug referred to as day 0 of pregnancy
- Verification of same strain and source of both sexes: yes

Duration of treatment / exposure:

continuously exposure to 2-EH (0, 0.009, 0.03, or 0.09%) microencapsulated in the feed from gestational day 0-17

Frequency of treatment:

continuously ad libitum feed

Duration of test:

sacrifice at gestational day 17

Remarks:

Doses / Concentrations:
0.009, 0.03 or 0.09%
Basis:
nominal in diet

Remarks:

Doses / Concentrations:
0, 17, 59 and 191 mg/kg bw/d
Basis:
other: calculated consumption, based on gestational food consumption

No. of animals per sex per dose:

28

Control animals:

yes, plain diet

Details on study design:

- Dose selection rationale: DEHP was previously evaluated for potential developmental toxicity in timed-pregnant Swiss (CD-I) mice exposed via the diet throughout gestation (gd 0 to 17) (Tyl et oZ., 1988). An average dose of 44 mg/kg/day (0.025% DEHP in feed) was the maternal and embryo/fetal NOAEL. An increased incidence of malformations was observed at 91 mg/kg/day (0.05% DEHP in feed) in the absence of other indications of maternal and embryo/fetal toxicity. At 191 and 292 mg/kg/day (0.10% and 0.15% DEHP in feed), maternal toxicity (reduced weight gain during treatment and increased relative liver weight) was observed, as well as decreased fetal weight and an increased incidence of prenatal mortality and fetal malformations. Based upon these findings, additional studies were designed to characterize the developmental toxicity of DEHP's principal metabolites (MEHP and 2-18 ethylhexanol) at approximately equimolar doses and under comparable experimental conditions as those from the study of DEHP in mice (Tyl et aZ., 1988). Accordingly, the concentrations of MEHP in feed included 0% (control), 0.017%, 0.035%, 0.070%, and 0.140%, with the average daily intake of 0, 35, 73, 134, and 269 MEHP mg/kg/day, respectively (NTP, 1990), approximately equivalent on a molar basis to the dose levels of DEHP used by Tyl et aZ. (1988). The target concentrations of 2-EH in feed employed for this study included 0.00% (control), 0.009%, 0.030%, and 0.090%. The expected average daily intake of 2-EH at the proposed dietary concentrations were 0, 15, 52.5, and 157.5 mg/kg/day, respectively. (The actual intake was 0, 17, 59 and 191 mg/kg/day; see results.) Therefore, the target dietary dose levels of 2-EH employed for this study were intended to encompass the range of intakes obtained with DEHP.

Maternal examinations:

CAGE SIDE OBSERVATIONS: Yes
- Time schedule: daily from gestation day 0-17

BODY WEIGHT: Yes
- Time schedule for examinations: on gestation days 0, 3, 6, 9, 12, 15, and 17

FOOD CONSUMPTION AND COMPOUND INTAKE (if feeding study): Yes
- Time schedule for examinations: on gestation days 0, 3, 6, 9, 12, 15, and 17

POST-MORTEM EXAMINATIONS: Yes
- Sacrifice on gestation day 17
- Organs examined: The maternal body, liver, and intact uterus were weighed

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

Fetal examinations:

- External examinations: Yes: all per litter
- Soft tissue examinations: Yes: all per litter
- Skeletal examinations: Yes: all per litter
- Head examinations: Yes: half per litter

Statistics:

analyses of variance (ANOVA), when ANOVA revealed a significant (p<0.05) dose effect, Dunnett's Multiple Comparison Test (Dunnett, 1955; 1964) compared each 2-EH-exposed group to the control group. One-tailed tests were used for all pairwise comparisons except maternal body and organ weights and fetal body weight, General Linear Models (GLM), chi square test, when a chi square test showed significant group differences, a one-tailed Fisher's exact probability test was used for pairwise comparisons of each 2-EH group with the control group.

Details on maternal toxic effects:

Maternal toxic effects:no effects

Details on maternal toxic effects:
No females died, delivered early or were removed from the study. Pregnancy rates were high and equivalent across all groups (93-96%); maternal
weight change for the gestational (and treatment) period, gd 0-17, was unaffected, as was weight change corrected for gravid uterine weight; maternal organ weights and food consumption were also unaffected; Treatment related clinical signs of toxicity were limited to hyperactivity observed in
one dam on gd 6, 9 and 12 at 0.090% and in one dam on gd 6 at 0.030%

Key result

Dose descriptor:

NOAEL

Effect level:

191 mg/kg bw/day

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:
There were no effects of exposure on the number of ovarian corpora lutea, or of uterine implantation sites (resorptions, dead fetuses or live fetuses) per litter. Live litter size and fetal body weight per litter (all fetuses, males or females) were equivalent across all groups.
There were also no effects of treatment on the incidence of malformations (external, visceral, skeletal or total) or variations, whether expressed as number or percentage of fetuses per litter or of litters with one or more affected fetuses. Examination of individual fetal findings also indicated no specific malformations or variations with a dose-related incidence.

Key result

Dose descriptor:

NOAEL

Remarks:

developmental

Effect level:

191 mg/kg bw/day

Based on:

test mat.

Basis for effect level:

other: no effects on: litter size and weights; number viable (number alive and number dead); sex ratio; grossly visible abnormalities; external, soft tissue and skeletal abnormalities;

Abnormalities:

not specified

Developmental effects observed:

not specified

In conclusion, 2-EH administered in the diet during gestation (gd 0-17) in CD1 mice at concentrations comparable to or exceeding those employed for DEHP and MEHP in the same study design, resulted in no maternal or developmental toxicity. It is therefore clear that 2-EH plays essentially no role in the expression of DEHP-induced maternal and developmental toxicity.

Effect on developmental toxicity: via oral route

Endpoint conclusion:

no adverse effect observed

Quality of whole database:

The available information comprises an adequate and reliable (Klimisch score 2) study from a reference substance with similar structure and intrinsic properties. Read-across is justified based on structural similarity between the source and target substances, the source substance being a product of the hydrolysis of the target substance (refer to endpoint discussion for further details).

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 no data available the toxicity to reproduction of Fatty acids, C18-unsatd., dimers, 2-ethylhexyl esters (CAS 68334-05-4). In order to fulfil the standard information requirements set out in Annex X, 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 and/or common chemical precursors or similar hydrolysis/breakdown products (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 and/or common chemical precursors or similar hydrolysis/breakdown products.

The read-across is either based structural similarity or on the metabolism of Fatty acids, C18-unsatd., dimers, 2-ethylhexyl esters (CAS 68334-05-4), in particular on the fact that the substance undergoes enzymatic ester hydrolysis resulting in the formation of Fatty acids, C18-unsatd., dimers and 2-ethylhexanol. A detailed analogue approach justification is provided in the technical dossier (see IUCLID Section 13).

Overview of developmental toxicity

CAS	Chemical name	Molecular weight	Toxicity to reproduction – Fertility	Toxicity to reproduction – Developmental Toxicity
68334-05-4 (a)	Fatty acids, C18-unsatd., dimers, 2-ethylhexyl esters	673.12	waiving	RA: CAS 104-76-7: equimolar NAEL = 987 mg/kg bw/day
104-76-7 (b)	2-ethylhexanol	130.23	--	Experimental result: NOAEL = 191 mg/kg bw/day

(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 substances are considered to be similar on the basis of common chemical precursors and common hydrolysis/breakdown products. The available endpoint information is used to predict the same endpoints for Fatty acids, C18-unsatd., dimers, 2-ethylhexyl esters (CAS 68334-05-4). A detailed analogue approach justification is provided in the technical dossier (see IUCLID Section 13).

 

Discussion

Toxicity to reproduction – (pre-natal) development

No studies on developmental toxicity and teratogenicity were available with Fatty acids, C18 unsatd. dimers 2-ethxlhexyl esters. Therefore, the metabolite 2-ethylhexanol was used for determination of possible hazards.

The information available on the developmental toxicity/teratogenicity of Fatty acids, C18-unsaturated, dimers is limited to summarised data from a Reproduction/Developmental Toxicity Screening Test electronically published by the US Environmental Protection Agency (http://www.epa.gov/chemrtk/pubs/summaries/ftadmrtr/c13651tc.htm) in which a NOAEL for both systemic and reproductive/developmental toxicity of 1858 mg/kg bw/day was reported.

There are no further data available on potential developmental/teratogenic effects of Fatty acids, C18-unsaturated, dimers or any other member of the chemical category they belong to. Skin contact and, to a lesser extent, ingestion represent the likely routes of human exposure. Taking into account the toxicokinetic behaviour of fatty acids in general and the available toxicity studies on Fatty acids, C18-unsaturated, dimers and/or structurally related substances, the weight of evidence does not indicate any potential for the induction of developmental/teratogenic effects by either route of exposure. For dimerised fatty acids, a very low level of absorption by the gastrointestinal tract is expected. Considering the low water solubility and lipophilic nature, the dermal absorption is expected negligible.

CAS 104-76-7

A developmental toxicity study was performed with 2-ethylhexanol, which was administered microencapsulated in the diet to pre-mated CD-1 mice (Tyl, 1991). Twenty-eight animals per group were treated continuously from Day 0 to Day 17 of gestation with dietary concentrations of 0.009, 0.03 or 0.09% in feed equivalent to 17, 59 and 191 mg/kg/day of the test substance. No females died, delivered early or were removed from the study. Pregnancy rates were high and equivalent across all groups (93-96%), maternal weight change for the gestational (and treatment) period (GD 0-17) was unaffected, as was weight change corrected for gravid uterine weight and maternal organ weights and food consumption were also unaffected. There were no effects of exposure on the number of ovarian corpora lutea, or of uterine implantation sites (resorptions, dead foetuses or live foetuses) per litter. Live litter size and foetal body weight per litter (all foetuses, males or females) were equivalent across all groups. There were also no treatment-related effects on the incidence of malformations (external, visceral, skeletal or total) or variations, whether expressed as number or percentage of foetuses per litter or of litters with one or more affected foetuses. Examination of individual foetal findings also indicated no specific malformations or variations with a dose-related incidence. In conclusion, the administered in the diet during gestation (GD 0-17) in CD1 mice at concentrations of 17, 59 and 191 mg/kg bw/day resulted in no maternal or developmental toxicity.

Based on the results, the developmental NOAEL for 2-ethylhexanol in mice was found to be 191 mg/kg bw/day.

 

Conclusions for toxicity to reproduction (development)

No studies on developmental toxicity and teratogenicity were available with Fatty acids, C18 unsatd. dimers, 2 -ethxlhexyl esters. Therefore, the hydrolysis product 2-ethylhexanol was used for determination of possible hazards. The results of the toxicologically most critical metabolite 2-ethylhexan-1-ol (NOAEL = 191 mg/kg bw/day) was used for further assessment.

Effects on developmental toxicity:

A waiver for the requirement to perform a prenatal developmental toxicity study in a 2nd species was included, as this requirement is considered not to add new information for hazard assessment and therefore is scientifically and, considering concerns regarding the use of vertebrate animals for experimental purposes, unjustified.

Justification for selection of Effect on developmental toxicity: via oral route:
Hazard assessment is conducted by means of read-across from structural analogues/surrogates. The selected study is the most adequate and reliable study based on the identified similarities in structure and intrinsic properties between source and target substances and overall assessment of quality, duration and dose descriptor level (refer to the endpoint discussion for further details).

Justification for classification or non-classification

Based on read-across from the structurally similar substances, the available data on toxicity to reproduction do not meet the classification criteria according to Regulation (EC) 1272/2008 or Directive 67/548/EEC, and are therefore conclusive but not sufficient for classification.