Reaction mass of 3,7-dimethyloct-6-en-1-yl 2-methylpropanoate and (2E)-3,7-dimethylocta-2,6-dien-1-yl 2-methylpropanoate and (2Z)-3,7-dimethylocta-2,6-dien-1-yl 2-methylpropanoate

Endpoint summary

Description of key information

For Geranyl Isobutyrate MCS the following results were derived:

Species	Guideline / Method	Result	Remarks
Daphnia magna	Read across from Citronellyl butyrate	48-h EC50: 0.41 mg/L	Key study, Rel. 2. Value derived from read-across to Citronellyl butyrate (CAS# 141-16-2) tested in an OECD TG 202.
Green algae (P. subcapitata)	Read across from Citronellyl butyrate	72-h ErC50: >0.16 mg/L 72-h ErC10: 0.083 mg/L 72 -h NOErC: 0.043 mg/L	Key study, Rel. 2. Values derived from read-across to Citronellyl butyrate (CAS# 141-16-2) tested in an OECDTG 201.

Additional information

The aquatic toxicity is assessed based on read-across from Citronellyl butyrate to Geranyl Isobutyrate.The executive summaries are presented in the Enpoint summaries of aquatic invertebrates and toxicity to aquatic algael. The read across rationale is presented below.

Aquatic toxicity ofGeranyl Isobutyrate MCS based on read across from data available for Citronellyl butyrate (CAS# 141-16-2).

 

Introduction and hypothesis for the analogue approach

Geranyl Isobutyrate MCS is a multi-constituent substance for which ca. 98.4% of the constituents are identified. The substance contains 4 constituents, all of which are Isobutyrate esters of a 3,7-dimethyloctanol chain containing no, 1 or 2 non-conjugated double bonds. About 70% of the known composition consists of 2 isomers of Geranyl Isobutyrate ‘mono’ with 2 non-conjugated double bonds, about 25% is Citronellyl Isobutyrate with 1 double bond, and a remaining <5% consists of another Citronellyl-like component with no double bond.

For Geranyl Isobutyrate MCS there are no experimental aquatic toxicity data available.In accordance with Article 13 of REACH, lacking information can be generated whenever possible by means other than experimental testing, i.e. applying alternative methods such as in vitro tests, QSARs, grouping and read-across.For assessing the aquatic toxicity of Geranyl Isobutyrate MCS, the analogue approach is selected because for a close structural analogue, Citronellyl butyrate, experimental data is available which can be used for read across

Hypothesis: Geranyl Isobutyrate MCS as a whole has similar aquatic toxicity potential as Citronellyl butyrate.

Available information:ForCitronellyl butyrate experimental acute and long-term algae and Daphnia data are available and acute Daphnia. The acute data arein the range of 0.1 - 1.0 mg/L. The one chronic value is in the range of 0.01 - 0.1 mg/L.In more detail:

Thealgaetest was performed according to OECD TG 201 (Rel. 1). Algae, at a starting cell concentration of 5E+03 cell/mL (nominal), were exposed to Citronellyl butyrate as an undiluted filtrate with a loading rate of 100 mg/L and to dilutions of this filtrate at 1:22, 1:10, 1:4.6 and 1:2.2. Test substance analysis was performed on the dilutions 1:10, 1:4.6 and 1:2.2 and on the undiluted filtrate. The respective measured concentrations were determined to be 0.043, 0.052, 0.063 and 0.16 mg/L. These measured concentrations were calculated as the geometric mean of the concentrations measured at all sampling times 0, 24, 48, and 72 hours. After 72 hours exposure, no statistically significant inhibitory effect on the growth rate of algae was seen up to and including the test item concentration of 0.043 mg/L. At the test concentrations of 0.052, 0.063 and 0.16 mg/L, inhibition of growth rates were 3.5%, 5.7% and 34.6%, respectively. Based on these findings, the 72-h ErC50 and ErC10 values are determined to be >0.16 and 0.083 mg/L, respectively (based on mean measured concentrations). The NOErC is 0.043 mg/L. The validity criteria were met and the study is considered reliable without restrictions.

TheDaphniatoxicity test was performed according to OECD TG 202 (Rel. 1). In a 48 h semi-static test daphnids were exposed to Citronellyl butyrate as an undiluted filtrate with a loading rate of 100 mg/L and to dilutions of this filtrate at 1:22, 1:10, 1:4.6 and 1:2.2. Test substance analysis was performed on the dilutions 1:4.6 and 1:2.2 and on the undiluted filtrate. The respective measured concentrations were determined to be 0.12, 0.32 and 0.74 mg/L. These measured concentrations were calculated as the arithmetic mean of the two geometric means which were determined from the test item concentrations measured at the start and end of each of the two test medium renewal periods. After 48 hours of exposure, no immobilized test organisms were determined in the control and up to and including the test item concentration of 0.12 mg/L. At the next higher test concentrations of 0.32 and 0.74 mg/L, 35% and 85% of the daphnids were immobile. The 48-hour EC50 was calculated to be 0.41 mg/L (95%-C.L: 0.32 - 0.53 mg/L) based on mean measured concentrations. The validity criteria are met and the study is considered reliable without restrictions.

Target chemical and source chemical(s)

Chemical structures of the target chemical and the source chemical are shown in the data matrix, including physico-chemical properties and available ecotoxicological information. Furthermore, a full list of constituents of Geranyl Isobutyrate MCS, including information relevant for read-across, is given in Appendix 1.

Purity / Impurities

NeitherGeranyl Isobutyrate MCS nor Citronellyl butyratecontain any impurities that are considered to impact the assessment of aquatic toxicity from read across.

Analogue approach justification

According to Annex XI section 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.

Analogue justification:For Geranyl Isobutyrate MCS the analogueCitronellyl butyrate was selected because this analogue has the same backbone and functional group and for Citronellyl butyrate acute oral toxicity information is available.

Structural similarities and differences:Geranyl Isobutyrate MCS and Citronellyl butyrate both have a 3,7-dimethyloctanol backbone and a butyric ester as a functional group. The difference is that some constituents in Geranyl Isobutyrate MCS have 2 double bonds while Citronellyl butyrate has one double bond in this octanol backbone. The ester bond is conjugated with this one of these double bonds not presented in the analogue. In addition, the butyl chain is an isobutyl chain in Geranyl Isobutyrate MCS, while this is a straight chain in the analogue.

Bioavailability:Based on the chemical structure and physico-chemical properties Geranyl Isobutyrate MCS and Citronellyl Butyrate will have the same bioavailability: the log Kows are all around 5.5

Reactivity:Geranyl Isobutyrate MCS and Citronellyl butyrate are expected to have the same reactivity based on being butyricesters. Geranyl Isobutyrate MCS and the constituents with a conjugated ester bond are expected to hydrolyse faster than the ones without such a conjugated ester bond.

Conversion of the effect values to Geranyl Isobutyrate MCS from Citronellyl butyrate: A log Kow correction is not needed because the estimated log Kow of Geranyl Isobutyrate MCS and Citronellyl butyrate are around 5.5. They also have the same molecular weight.

Uncertainty of the prediction:The Geranyl Isobutyrate MCS, due to the position of the two non-conjugated double bonds, belong, according to ECOSAR to the toxicity class of ‘allyl/vinyl esters’. The ‘Citronellyl-like’ structures are situated in the latter toxicity class. This results in minimally higher ECx values for these ‘Citronellyl-like’ structures but at this fairly high log Kow values (around 5.5) the difference in toxicity will be insignificant. 

Data matrix

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

Conclusions for hazard assessment and risk assessment

ForGeranyl Isobutyrate MCSno experimental aquatic toxicity information is available.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. The latter documentation is presented in the current document. For Citronellyl butyratethe lowest acute effect value is 0.41 mg/L (daphnids), while for algae a > 0.16 mg/l was derived. The only chronic effect value is a NOErC is 0.083 mg/L (algae). These results can be directly used for Geranyl Isobutyrate MCS.

Final conclusion on hazard and risk assessment: Geranyl Isobutyrate MCS has an acute Daphnia EC50 of 0.41 mg/l and for acute and long-term algae EC50 and NOErC of > 0.16 and 0.083 mg/l, respectively.

 

Data matrix presenting the information relevant for read across to Geranyl Isobutyrate MCS from Citronellyl butyrate.

Common name	Geranyl Isobutyrate MCS	Citronellyl butyrate
	Target	Source
Chemical name	n.a.	3,7-dimethyloct-6-en-1-yl butyrate
Chemical structures	For a full list of constituents, see Appendix 1.
CAS #	--	141-16-2
EC #	905-357-4	205-463-4
REACH registered	2018	Registered
Empirical formula	n.a.	C14H26O2
SMILES	n.a.	CCCC(=O)OCCC(C)CCC=C(C)C
Physico-chemical data
Molecular weight	n.a.	226
Physical state	Liquid	Liquid
Log Kow	5.7 (exp.)	5.54 (est.)
Ws (mg/L)	17.4 (exp.)	1.63 (est.)
Vp (Pa)	1.2 (exp.)	6.2 (est.)
Aquatic toxicity
Aquatic invertebrates 48-h EC50 (mg/L)	Read across 0.41	0.41
Aquatic algae 72-h ErC50 (mg/L) 72-h ErC10 (mg/L) 72-h NOErC (mg/L)	Read across: >0.16 0.083 0.043	>0.16 0.083 0.043

 

Appendix 1:Overview of data available for the different constituents of Geranyl Isobutyrate MCS, and the structural analogue Citronellyl butyrate

CHEMICAL NAME	Geranyl Isobutyrate ‘mono’	Neryl isobutyrate	Citronellyl isobutyrate	Minor Citronellyl-like constituent	Citronellyl butyrate
% in product	56.3 (main)	13.7	24.7 (main)	3.7	n.a.
CAS	2345-26-8	2345-24-6	97-89-2	71662-25-4	141-16-2
MW	224	224	226	228	226
Phys-chem
Appearance	Liquid	-	Liquid	-	Liquid
Log Kow	5.4 (est.)	5.4 (est.)	5.4 (exp.)	5.6 (est.)	5.5 (est.)
Vp (Pa)	1.1 (est.)	1.1 (est.)	1.9 (est.)	3.4 (est.)	6.2 (est.)
Ws (mg/L)	0.82 (est.)	0.82 (est.)	0.68 (est.)	0.56 (est.)	1.63 (est.)
Environmental fate
Biodegradation	Readily	-	-	-	Readily *
Aquatic toxicity
Daphnia magna(mg/L) 48-h EC50	48 mg/L (WoE) *	-	-	-	0.41
Aquatic algae (mg/L) 72-h ErC50 72-h ErC10 72-h NOErC	ca. 48 mg/L (WoE) * - -	- - -	- - -	- - -	>0.16 0.083 0.043
ECOSAR (mg/L): - Daphnia acute - Algae acute - Algae chronic	0.458 0.114 0.088	0.458 0.114 0.088	0.409 0.100 0.079	0.364 0.088 0.072	0.367 0.089 0.072

* Data taken from ECHA website (disseminated data)