Reaction mass of 3,7-dimethyl-1-octyl acetate and citronellyl acetate

Biodegradation in water: screening tests

Description of key information

Citronellyl Acetate Multi is readily biodegradable, based on read-across from Citronellyl Acetate mono, tested in a study according to OECD TG 301B.

Key value for chemical safety assessment

Biodegradation in water:

readily biodegradable

Type of water:

freshwater

Additional information

The biodegradability in water is assessed based on read-across from Citronellyl Acetate mono to Citronellyl Acetate Multi. The executive summary of the source information is presented below, followed by the read-across rationale.

Citronellyl Acetate mono biodegradability information

The biodegradability of Citronellyl Acetate mono was determined in a study according to OECD TG 301B (Modified Sturm Test) and in compliance with GLP criteria. Test substance at a concentration of 10 mg/L (Total Organic Carbon (TOC)) was inoculated with secondary effluent from an unacclimatised activated sludge plant for 28 days under aerobic conditions. Samples were taken at days 3, 8, 10, 14, 17, 21, 24 and 28 after the start of the test, and carbon dioxide in the headspace, and the concentration of inorganic carbon in the test medium determined. The total inorganic carbon (TIC) in the vessel is calculated by subtracting the TIC produced in a control, and the percentage biodegradation calculated as TIC/TOC*100%. Biodegradation reached 64.6% on day 10, and further increased to 82.1% on day 28. The 10-day window criterion is met. The substance is concluded to be readily biodegradable.

Biodegradation of Citronellyl Acetate Multi based on read across from data available for Citronellyl Acetate mono (CAS# 150-84-5).

Introduction and hypothesis for the analogue approach

Citronellyl Acetate Multiis a multi-constituent. The main constituent of Citronellyl Acetate Multi isCitronellyl Acetate mono. It has an unsaturated hydrocarbon backbone to which an acetic ester is attached. The minor constituent is Dihydro-Citronellyl Acetate, which has a similar but a saturated backbone and has an acetic ester attached to this.

For Citronellyl Acetate Multi, there are no experimental biodegradation data 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 biodegradability of Citronellyl Acetate Multi, the analogue approach is selected because for the main constituent, Citronellyl Acetate mono (CAS# 150-84-5), experimental data is available which can be used for read across.

Hypothesis:The ready biodegradability of Citronellyl Acetate Multi is the same as for Citronellyl Acetate mono because this is its main constituent. Also minor constituent, Dihydro-Citronellyl Acetate, is readily biodegradable based on structural similarity and modelling results.

Available information:The biodegradability of the Citronellyl Acetate mono was determined in a study according to OECD TG 301B and in compliance with GLP criteria and was considered readily biodegradable (82% after 28 days) meeting the 10-day window (Klimisch 1).

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.

Purity / Impurities

The purity and impurities of the target chemical do not indicate other biodegradation potential other than indicated by the parent substance. The impurities are all below < 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 CitronellylAcetate Multi its key constituent Citronellyl Acetate mono was selected as an analogue for read-across because it can cover almost 70% of its biodegradation potential. The read across needs to cover the biodegradability of the minor constituent: Dihydro-Citronellyl Acetate.

Structural similarities and differences: Citronellyl Acetate Multi consists mainly of Citronellyl Acetate mono. The structural similarity with the Dihydro-Citronellyl Acetate is that it has the same backbone and functional acetate group. The difference is that Dihydro-Citronellyl Acetate’s backbone is saturated (and does not contain a double bond). This results in a 2H higher molecular weight 198 and 200, respectively.

Bioavailability: Citronellyl Acetate Multi’s key constituent is the same substance as Citronellyl Acetate mono. Dihydro-Citronellyl Acetate has similar bioavailability based on log Kow (log Kow difference between the two is < 0.5: 4.6 and 5, respectively).

Biodegradable fragments: Citronellyl Acetate Multi’ key constituent is the same as Citronellyl Acetate mono. Dihydro-Citronellyl Acetate has similar biodegradable fragments as presented in BIOWIN 5 and 6 and have therefore almost the same probability, which is between 0.6 and 0.8 for biodegradation.

Uncertainty of the prediction: There are no other uncertainties than those already discussed above.

Conclusions on biodegradability

For Citronellyl Acetate Multi no biodegradation information is available. For it key constituent Citronellyl Acetate mono such information is available. For its minor constituent, Dihydro-Citronellyl Acetate, read-across is used to predict its ready biodegradability and presented with adequate and reliable documentation.Citronellyl Acetate mono is readily biodegradable in an OECD TG 301B. This result can be used for Dihydro- Citronellyl Acetate based on similar backbone and the same functional group. This is supported with BIOWIN 5 and 6 modelling.

Final conclusion:Citronellyl Acetate Multiis readily biodegradable.

 

Data matrixpresenting the information relevant for read across toCitronellyl Acetate Multi from Citronellyl Acetate mono and Dihydro Citronellyl Acetate on biodegradation

Substance	Citronellyl Acetate Multi	Citronellyl Acetate mono Main constituent	Dihydro-Citronellyl Acetate Minor constituent
Read-across	Target	Source	Target
Chemical name	-
Structure	See constituents
% in product	See constituents	60-75	10-20
CAS	See constituents	150-84-5	20780-49-8
EC no	908-114-0	205-775-0	244-034-6
MW	n.a.	198	200
Phys-chem
Appearance	Liquid	Liquid (ECHA site)	Liquid (ECHA site)
Log Kow	4.6 (exp.)	4.6 (ECHA site)	4.6 (ECHA site)
Ws (mg/L)	12.1 (exp)	5.7 (ECHA site)	4.7 (ECHA site)
Vp (Pa)	2.6 (exp)	7.0 (ECHA site)	12.9 (ECHA site)
Environm. fate
Biodegradability experimental	Readily biodegradable (RA)	Readily biodegradable (82%) (OECD 301B)	Readily biodegradable (ECHA site)
Biodegradability BIOWIN 5 + 6	--	Probability for ready biodegradability 0.62 and 0.72	Probability for ready biodegradability 0.60 and 0.77

RA = read-across.