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

Biodegradation in water: screening tests

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

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

Adequacy of study:

key study

Rationale for reliability incl. deficiencies:

other: read-across from a guideline study

Justification for type of information:

The read across justification is presented in the Endpoint summary Biodegradation in water. The accompanying files are also attached there.

Reason / purpose for cross-reference:

read-across source

Key result

Parameter:

% degradation (O2 consumption)

Value:

67

Sampling time:

28 d

Remarks on result:

other: read-across from Geranyl Isobutyrate ('mono')

Interpretation of results:

readily biodegradable

Reference 2

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

experimental study

Adequacy of study:

key study

Study period:

22 Aug 2011 - 10 Oct 2011

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Justification for type of information:

This information is used for ready across to Geranyl Isobutyrate MCS.

Qualifier:

according to guideline

Guideline:

OECD Guideline 301 F (Ready Biodegradability: Manometric Respirometry Test)

Version / remarks:

1992

Deviations:

no

Qualifier:

according to guideline

Guideline:

EU Method C.4-D (Determination of the "Ready" Biodegradability - Manometric Respirometry Test)

Version / remarks:

2008

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Remarks:

Swiss Federal Office of Public Health Consumer protection directorate. Notification authority for chemicals CH-3003 Bern (d.d. 8 February 2011)

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, domestic (adaptation not specified)

Details on inoculum:

- Source of inoculum/activated sludge: Fresh activated sludge from a biological waste water treatment plant treating predominantly domestic sewage (Bois-de-Bay, Satigny, Switzerland).
- Preparation of inoculum for exposure: The sludge is collected in the morning, washed three times in the mineral medium (by centrifuging at 1000 g for 10 minutes, discarding the supernatant and resuspending in mineral medium) and kept aerobic until being used on the same day.

Duration of test (contact time):

48 h

Initial conc.:

30 mg/L

Based on:

test mat.

Initial conc.:

65.1 mg/L

Based on:

ThOD

Parameter followed for biodegradation estimation:

O2 consumption

Details on study design:

TEST CONDITIONS
- Composition of medium: Mineral medium was prepared according to OECD 301 A.
- Test temperature: 21.9 - 22.7 °C
- pH: initial: 7.6, final: 7.49-8.14
- pH adjusted: no
- Suspended solids concentration: 30 mg/L (dry weight)

TEST SYSTEM
- Culturing apparatus: Oxitop Control System (Wissenschaftlich-Technische Werkstätten, Weilheim, Germany)
- Number of culture flasks/concentration: 2

SAMPLING
- Sampling frequency: Every day the oxygen consumption of each flask was recorded.

CONTROL AND BLANK SYSTEM
- Inoculum blank: 2 recplicates
- Reference substance: 2 replicates

Reference substance:

benzoic acid, sodium salt

Key result

Parameter:

% degradation (O2 consumption)

Value:

67

St. dev.:

1.4

Sampling time:

28 d

Parameter:

% degradation (O2 consumption)

Value:

74

St. dev.:

0

Sampling time:

48 d

Details on results:

For % biodegradation at different time points, see table in 'Any onther information incl. tables'.
For % biodegradation curve of test substance, see attached illustration.
The 10-day window criterion is not fulfilled (21% biodegradation on day 3 and 53% on day 13), however since the test substance contains 3 isomers the 10-day window should not be used as a pass fail criterion.

Results with reference substance:

Degradation of sodium benzoate reached 96% (± 2.8%) after 28 days.

O2 uptake (mg/L, adjusted to nominal concentrations):

	Days:		2	3	13	18	21	28	48
O2 uptake of sludge (inoculum blank)	1a	B1	18.8	21.5	35.0	37.7	40.4	44.4	57.9
	2a	B2	17.5	20.2	32.3	35.0	39.0	39.0	44.4
	mean	B	18.2	20.9	33.7	36.4	41.7	41.7	51.2
O2 uptake of Test Subst. + sludge	19a	C1	22.9	35.0	67.3	75.4	79.4	84.8	99.6
	20a	C2	21.5	33.7	68.7	75.3	79.3	86.1	99.5
O2 uptake of Test Substance		C1-B	4.8	14.2	33.7	39.1	41.1	43.1	48.5
		C2-B	3.3	12.8	35.0	39.0	41.0	44.4	48.4
% biodegradation of test substance		D1	7	22	52	63	66	66	74
		D2	5	20	54	63	68	68	74
	mean	D	6	21	53	63	67	67	74

 

Calculations:

B1, B2, C1, C2, A1, A2, E1: Experimental O2 uptake values

B = (B1+B2) / 2

D1 = 100 * (C1-B) / ThOD * [S]

D2 = 100 * (C2 – B) / ThOD * [S]

D = (D1 + D2) / 2

[S]: initial test substance concentration (mg/L)

Validity criteria fulfilled:

yes

Remarks:

See "Overall remarks" for details on validity criteria.

Interpretation of results:

readily biodegradable

Conclusions:

Geranyl Isobutyrate 'mono' undergoes 67% biodegradation after 28 days (74% after 48 days) in the test conditions and it can be regarded as readily biodegradable, because this 'mono' is actually a multi-constituent.

Executive summary:

For Geranyl Isobutyrate ('mono'), the ready biodegradability was determined in a study according to OECD TG 301F (Manometric Respirometry Test) and in compliance with GLP criteria. In this study 30 mg/L test substance (65.1 mg/L based on ThOD) was inoculated with fresh activated sludge from a biological waste water treatment plant treating predominantly domestic sewage for 28 days. After 28 days, 67% biodegradation was observed which further increased to 74% after 48 days. The validity criteria of the study are met. The substance can be regarded as readily biodegradable, because this 'mono' is actually a multi-constituent.

Description of key information

Geranyl Isobutyrate MCS is readily biodegradable based on Geranyl Isobutyrate 'mono' which was tested in an OECD TG 301F.

Key value for chemical safety assessment

Biodegradation in water:

readily biodegradable

Type of water:

freshwater

Additional information

Biodegradability in water is assessed based on read-across from Geranyl Isobutyrate 'mono' to Geranyl Isobutyrate MCS. The executive summary of the source information is presented below, followed by the read-across rationale.

Geranyl Isobutyrate 'mono' and its ready biodegradability

For Geranyl Isobutyrate ('mono'), the ready biodegradability was determined in a study according to OECD TG 301F (Manometric Respirometry Test) and in compliance with GLP criteria. In this study 30 mg/L test substance (65.1 mg/L based on ThOD) was inoculated with fresh activated sludge from a biological waste water treatment plant treating predominantly domestic sewage for 28 days. After 28 days, 67% biodegradation was observed which further increased to 74% after 48 days. The validity criteria of the study are met. The substance can be regarded as readily biodegradable, because this 'mono' is actually a multi-constituent.

Biodegradation of Geranyl Isobutyrate MCS based on read across from data available for Geranyl Isobutyrate ‘mono’ (CAS# 2345-26-8).

 

Introduction and hypothesis for the analogue approach

Geranyl Isobutyrate MCS is a multi-constituent substance for which 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 biodegradation 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 biodegradation of Geranyl Isobutyrate MCS, the analogue approach is selected because for the Geranyl Isobutyrate ‘mono’ experimental biodegradation information is available which can be used for read across. 

Hypothesis: The ready biodegradability of Geranyl Isobutyrate ‘mono’ is considered to be representative for all constituents of Geranyl Isobutyrate MCS on the basis of their very close structural analogy. If Geranyl Isobutyrate ‘mono’ is readily biodegradable, Geranyl Isobutyrate MCS is readily biodegradable.

Available information: No experimental data on the biodegradation potential of Geranyl Isobutyrate MCS is available. Read-across is performed to Geranyl Isobutyrate ‘mono’. For Geranyl Isobutyrate ‘mono’ a ready biodegradation study was performed according to OECD TG 301F (Manometric Respirometry test) and in compliance with GLP. In this study, 30 mg/L test substance was inoculated with fresh activated sludge form a biological waste water treatment plant treating predominantly domestic waste. Under the conditions of the test, 67% of Geranyl Isobutyrate ‘mono’ was biodegraded after 28 days. The 10-day window criterion was not met which is attributable to the tested substance consisting of 3 isomers. The 10-d window is therefore not used as a pass fail criterion for ready biodegradation. Geranyl Isobutyrate ‘mono’ is qualified as readily biodegradable.

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 environmental fate information. Furthermore, a full list of constituents of Geranyl Isobutyrate MCS, including information relevant for read-across, is given in Appendix 1.

Purity / Impurities

Neither Geranyl Isobutyrate MCS nor Geranyl Isobutyrate ‘mono’ contain any impurities that are considered to impact the assessment of biodegradation from read across.

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. Geranyl Isobutyrate ‘mono’ was selected as an analogue for read-across because it shares the same backbone and the same functional group of all constituents of Geranyl Isobutyrate MCS. Moreover, Geranyl Isobutyrate MCS consists for ca. 71% of two isomers of Geranyl Isobutyrate ‘mono’.

Structural similarities and differences: All constituents are Isobutyrate esters of a 3,7-dimethyloctanol chain. The only difference is the number of non-conjugated double bonds in the chain. In Table 1, the structural fragments with which the biodegradation can be predicted are presented, showing the similarity between the main constituents.  

Bioavailability: In view of the limited structural differences also the bioavailability based on physico-chemical properties such as water solubility and log Kow (around 5.5) is very similar .

 

Uncertainty of the prediction: To further support the analogy between the two constituents,BIOWIN(v4.10) predictions are made for the two main constituents of Geranyl Isobutyrate MCS, Geranyl Isobutyrate ‘mono’ and Citronellyl Isobutyrate.Only BIOWIN modules 5 (‘MITI-linear’) and 6 (‘MITI-non-linear’) are used because these two models are based on ready biodegradability tests, which is the endpoint to be predicted. The identified biodegradation fragments are identical in both substances but vary slightly in their number present in each structure. As Geranyl Isobutyrate ‘mono’ has been shown experimentally to be readily biodegradable the other constituent Citronellyl Isobutyrate will be readily biodegradable.

 

Table 1: Summary of BIOWIN predicted data for the main constituents Geranyl Isobutyrate ‘mono’ and Citronellyl Isobutyrate, the latter being a constituent of the first one.

		Geranyl Isobutyrate			Citronellyl Isobutyrate
Fragment	#	BIOWIN 5	BIOWIN 6	#	BIOWIN 5	BIOWIN 6
Ester [-C(=O)-O-C]	1	0.3437	2.4462	1	0.3437	2.4462
Methyl [-CH3]	5	0.0021	0.0971	5	0.0021	0.0097
-CH2- [linear]	3	0.1482	1.2885	4	0.1977	1.7180
-CH- [linear]	1	-0.0507	-0.0998	2	-0.1013	-0.1995
-C=CH [alkenyl hydrogen]	2	0.0124	0.0570	1	0.0062	0.0285
MW	-	-0.6674	-6.4766	-	-0.6734	-6.5348
Const		0.7121	-	-	0.7121	-
Overall score		0.5005	0.4596		0.4870	0.5203

 

With an increasing number of constituents, the ready biodegradability window within the log phase of biodegradation may also increase. Therefore the 10-d window criterionis not applied as a pass fail criterion for multi-constituents. The 60% degradation criterion is passed and the substance can be regarded ready biodegradable. There are no uncertainties other than those already addressed above.

Data matrix

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

Conclusions for environmental fate

The constituents of Geranyl Isobutyrate MCS are concluded to be readily biodegradable and therefore Geranyl Isobutyrate MCS will be assessed as readily biodegradable as well.

 

Data matrix presenting the information relevant for read across to Geranyl Isobutyrate MCS from Geranyl Isobutyrate ‘mono’

Common name	Geranyl Isobutyrate MCS	Geranyl Isobutyrate ‘mono’
	Target	Source
Chemical name	n.a.	(2E)-3,7-dimethylocta-2,6-dien-1-yl 2-methylpropanoate
Chemical structures	For a full list of constituents, see Appendix 1.
CAS #	--	2345-26-8
EC #	905-357-4	219-062-7
REACH registration	2018	Registered
Empirical formula	n.a.	C14H24O2
SMILES	n.a.	CC(C)C(=O)OC\C=C(/C)CCC=C(C)C
Physico-chemical data
Molecular weight	n.a.	224.3
Physical state	Liquid	Liquid
Log Kow	5.7 (exp.)	5.38 (exp.)
Ws (mg/L)	17.4 (exp.)	0.82 (exp.)
Vp (Pa)	1.2 (exp.)	1.07 (exp.)
Environmental fate
Biodegradation	Based on read-across: Readily biodegradable	Readily biodegradable

 

Appendix 1:Overview of data available for the different constituents ofGeranyl Isobutyrate MCS.

CHEMICAL NAME	Geranyl Isobutyrate ‘mono’	Neryl Isobutyrate	Citronellyl Isobutyrate	Minor Citronellyl-like constituent
Structure
% in product	56.3 (main)	13.7	24.7 (main)	3.7
CAS	2345-26-8	2345-24-6	97-89-2	71662-25-4
MW	224	224	226	228
Physico-chemical data
Appearance	Liquid	-	-	-
Log Kow	5.4 (est.)	5.4 (est.)	5.5 (est.)	5.6 (est.)
Ws (mg/L)	0.8 (est.)	0.8 (est.)	0.7 (est.)	0. 6 (est.)
Vp (Pa)	1.1 (est.)	1.1 (est.)	1.9 (est.)	3.4 (est.)
Environmental fate
Biodegradability	Readily (OECD 301F)	-	-	-