ETHYL 2-METHYL-4-PENTANOATEETH OXANOATE-369 CRUDE

Endpoint summary

Description of key information

The substance in not a skin sensitiser based on read across with Ethyl-2‐methylpent‐3‐enoate for which the following results were found: 

DPRA: Negative based on read-across from an OECD TG 442C test performed with main constituent Ethyl-2‐methylpent‐3‐enoate; KeratinoSens: Negative based on read-across from an OECD TG 442D test performed with main constituent Ethyl-2‐methylpent‐3‐enoate. Therefore Ethyl-2‐methylpent‐3‐enoate is not sensitising using OEcD TG 497

 

Key value for chemical safety assessment

Skin sensitisation

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (not sensitising)

Additional information:

First the executive summaries of the in vitro test battery consisting of DPRA (OECD 442C) and KeratinoSens (OECD 442D) performed with the major constituent, Ethyl-2‐methylpent‐3‐enoate, is presented and thereafter the read across justification.

DPRA

In an in chemico (DPRA) study, performed according to OECD guideline 442C and in accordance with GLP principles, the reactivity of the Substance towards model synthetic peptides containing either cysteine (SPCC) or lysine (SPCL) was determined. Isopropanol was found to be an appropriate solvent to dissolve the test substance in and was therefore used in this DPRA study. Cinnamic aldehyde was used as a positive control. Following incubation of the test substance with either SPCC or SPCL, the relative peptide concentration was determined by High-Performance Liquid Chromatography (HPLC) with gradient elution and spectrophotometric detection at 220 nm and 258 nm. SPCC and SPCL Percent Depletion Values were calculated and used in the prediction model. All acceptability criteria were met and therefore, the study was considered to be valid. No precipitate or phase separation was observed in any of the samples before and after the incubation. In the cysteine reactivity assay the test item showed 1.4% SPCC depletion and in the lysine reactivity assay the test item showed 2.8% SPCL depletion. The mean of the SPCC and SPCL depletion was 2.1% and as a result the test item was considered to be negative in the DPRA and classified in the “no or minimal reactivity class” when using the Cysteine 1:10 / Lysine 1:50 prediction model.

KeratinoSens

In an in vitro (KeratinoSens) study, performed according to OECD guideline 442D and in accordance with GLP principles, the ability of the test substance to activate the antioxidant/electrophile responsive element (ARE)-dependent pathway was determined. The test item was dissolved in dimethyl sulfoxide (DMSO) at 200 mM. From this stock 11 spike solutions in DMSO were prepared. The stock and spike solutions were diluted 100-fold in the assay resulting in test concentrations of 0.98 – 2000 μM (2-fold dilution series). The highest test concentration was the highest dose required in the current guideline. In experiment 2, precipitation was observed at the start of the incubation period in the 96-well plates, at the highest tested dose level of 2000 μM. Three independent experiments were performed. Overall it is concluded that the test conditions were adequate and that the test system functioned properly. In the first experiment, the test item showed toxicity (IC30 value of 26 μM). A biologically relevant induction of the luciferase activity (EC1.5 value of 1.1 μM) was measured. The maximum luciferase activity induction (Imax) was 3.10-fold leading to an individual run conclusion of positive since positive results (>1.5-fold induction) were observed at test concentrations < 1000 μM with a cell viability of >70% compared to the vehicle control. In the second experiment, the test item showed no toxicity (no IC30 and IC50 value). No biologically relevant induction of the luciferase activity (no EC1.5 value) was measured at any of the test concentrations. The maximum luciferase activity induction (Imax) was 1.29-fold leading to an individual run conclusion of negative assay since negative results (<1.5-fold induction) were observed at test concentrations up to 2000 μM. Since the first two experiments were not concordant, a third experiment was performed to provide a final conclusion. In the third experiment, the test item showed no toxicity (no IC30 and IC50 value). The test item showed no biologically relevant induction of the luciferase activity (no EC1.5 value) at any of the test concentrations. The maximum luciferase activity induction (Imax) was 1.45-fold leading to an individual run conclusion of negative assay since negative results (<1.5-fold induction) were observed at test concentrations up to 2000 μM. Overall, the test item is classified as negative in the KeratinoSensTM assay since negative results (<1.5-fold induction) were observed in two out of three experiments at test concentrations up to 2000 μM with cell viability > 70% compared to the vehicle control. In conclusion, the test substance is classified as negative (no activation of the antioxidant/electrophile responsive element (ARE)-dependent pathway in keratinocytes).

Skin sensitisation potential of Eth Oxanoate 369 Crude based on read-across from data available for Ethyl-2-methyl-3-pentenoate (CAS# 58625-89-1) its main constituent

Introduction and hypothesis for the analogue approach

The multi-constituent substance Eth Oxanoate 369 Crude consists of two main constituents: 62% Ethyl-2-methyl-3-pentenoate (CAS# 58625-89-1) and 32% Ethyl-2‐methylpentanoate (CAS# 39255-32-8). For Eth Oxanoate 369 Crude, no experimental skin sensitisation data are available. In accordance with Article 13 of REACH, lacking information can be generated by means other than experimental testing, i.e. applying alternative methods such as, QSARs, grouping and read-across. For assessing the skin sensitisation potential of Eth Oxanoate 369 Crude, the analogue approach is selected because for the major constituents, Ethyl-2-methyl-3-pentenoate, reliable skin sensitisation information is available which can be used for read-across.

Hypothesis: Eth Oxanoate 369 Crude has the same skin sensitisation potential as Ethyl-2-methyl-3-pentenoate based on similarity in chemical structure, physico-chemical properties and reactivity potential.

Available information: For the major constituent (Ethyl-2‐methylpent‐3‐enoate), an in vitro test battery consisting of DPRA (OECD 442C) and KeratinoSens (OECD 442D) has been performed which were both negative.  

Target chemical and source chemical

Chemical structures of the target chemical and the source chemical are shown in the data matrix, including physico-chemical properties.

Purity / Impurities

The major and minor constituents of Eth Oxanoate 369 Crude are presented in the Data matrix. The impurities of Eth Oxanoate 369 Crude are < 10%.

Analogue approach justification

According to Annex XI 1.5, read-across can be used to replace testing when the similarity can be based on a common backbone and a common functional group. When using read-across the result derived should be applicable for C&L and/or risk assessment and it should be presented with adequate and reliable documentation, which is presented below.

Analogue selection: For Eth Oxanoate 369 Crude, the constituent Ethyl-2-methyl-3-pentenoate was selected as source chemical for read-across because it is the major constituent (62%) of Eth Oxanoate 369 Crude and experimental skin sensitisation data is available.

Structural similarities and differences: The major constituent, Ethyl-2-methyl-3-pentenoate (62%) has a molecular weight of 142 g/mol and has a similar structure to the minor constituent (32%), Ethyl-2‐methylpentanoate, which has a molecular weight of 144 g/mol. The only difference in their structures is that Ethyl-2-methyl-3-pentenoate has a double bond on the carbon 3 of the pentene ester, which the minor constituent does not have.

Dermal bioavailability: The bioavailability of the constituents of Eth Oxanoate 369 Crude and Ethyl-2-methyl-3-pentenoate are very similar based on similarities in chemical structures, water solubility and log Kow.  

Skin sensitisation reactivity: The reactivity of the major constituent, Ethyl-2-methyl-3-pentenoate, is similar to the reactivity of the minor constituent due to absence of skin sensitisation fragments as is supported by the OECD Toolbox (v4.5 and presented behind the data matrix).

Remaining uncertainties: There are no uncertainties other than those already addressed in the previous sections. The information on the ECHA dissemination site of the minor constituent presents absence of classification and labelling for skin and eye irritation (https://echa.europa.eu/nl/registration-dossier/-/registered-dossier/10528) further supports the read across.

Data matrix

The relevant information on physico-chemical properties and toxicological characteristics are presented in the data matrix below.

Conclusions on skin sensitisation for hazard and risk assessment

For Eth Oxanoate 369 Crude no skin sensitisation data is available. Read-across from its main constituent, Ethyl-2-methyl-3-pentenoate, is used to fill this data gap. When using read-across, the result derived should be applicable for C&L and/or risk assessment, and be presented with adequate and reliable documentation. This documentation is presented in the current text. The in vitro testing battery consisting of DPRA (OECD 442C) and KeratinoSens (OECD 442D) showed no skin sensitising potential for the main constituent. This information can be used for read across to Eth Oxanoate 369 Crude.

Final conclusion: Eth Oxanoate 369 Crude is not a skin sensitiser.

Data matrix to support the read-across to Eth Oxanoate 369 Crude from Ethyl-2-methyl-3-pentenoate for skin sensitisation

Endpoint	Eth Oxanoate 369 Crude	Ethyl-2-methyl-3-pentenoate (Z-isomer)	Ethyl-2‐methylpentanoate
	Target	Major constituent Source	Minor constituent
Chemical structure
CAS number	Not applicable	58625-89-1	39255-32-8
EC number	952-991-2	854-058-4	254-384-1
Typical conc. (%)	Not applicable	62	32
REACH registered	-	registered	registered
Empirical formula	Not applicable	C8H14O2	C8H16O2
Molecular weight	142 – 144	142	144
Phys-chem
Log Kow	3.0 (measured: main constituent)*	2.54 (EPISUITE) 3.1 (measured)*	2.76 (EPISUITE) 2.09 (ECHA dissemination site)
Water Solubility (mg/L)	612.3 (measured: main constituent)	612.3 (measured)	467 (ECHA dissemination site)
Human health endpoints
Skin irritation	Read across from main constituent	Not irritating (OECD 439, IFF 2021)	Not irritant (ECHA dissemination site)
Skin corrosion	Read across from main constituent	Not corrosive (OECD 431)	Not irritant (ECHA dissemination site)
Skin sensitisation	Read across from main constituent	Negative (OECD 442C) Negative (OECD 442D)	Not sensitising (ECHA dissemination site)

*the same substance is measured twice with log Kow 0.1 difference

 

QSAR Toolbox (v4.5) profilers sensitisation

Substance identity	3-Pentenoic acid, 2-methyl-, ethyl ester, (Z)-	Ethyl-2‐methyl-3-pentanoate
Structure
CAS number	58625-89-1	39255-32-8
SMILES	CCOC(=O)C(C)C=CC	CCCC(C)C(=O)OCC
Profilers general mechanistic
Protein binding potency Cys (DPRA 13%)	DPRA less than 9% (DPRA 13%) DPRA less than 9% (DPRA 13%) >> Non-Conjugated carboxylic acids and esters (non reactive)	DPRA less than 9% (DPRA 13%) DPRA less than 9% (DPRA 13%) >> Non-Conjugated carboxylic acids and esters (non reactive)
Protein binding by OECD	No alert found	No alert found
Protein binding by OASIS	No alert found	No alert found
Endpoint Specific
Respiratory sensitisation	No alert found	No alert found
Protein Binding Potency h-CLAT	No alert found	No alert found
Protein binding alerts for skin sensitization according to GHS	No alert found	No alert found
Protein binding alerts for skin sensitization by OASIS	No alert found	No alert found

 

Justification for classification or non-classification

The substance is not a skin sensitiser based on read across from Ethyl-methyl3pentenoate which was tested in in vitro tests: DPRA and Keratinosens in accordance with EU CLP (EC No. 1272/2008 and its amendments).