Reaction mass of 6,6-dimethyl-2-methylidenebicyclo[3.1.1]heptane and rel-6,6-dimethylspiro[bicyclo[3.1.1]heptane-2,2'-oxirane]

Biodegradation in water: screening tests

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

experimental study

Adequacy of study:

key study

Study period:

The study was performed between October and November 2012.

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Justification for type of information:

The biodegradation information of this source substance is used for read across to Rosemarel.

Qualifier:

according to guideline

Guideline:

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

Version / remarks:

1992

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, domestic, non-adapted

Details on inoculum:

Fresh activated sludge from a biological waste water treatment plant treating predominantly domestic sewage was used. It was collected from Bois-de-Bay, Satigny, Switzerland.

Duration of test (contact time):

28 d

Initial conc.:

30 mg/L

Based on:

test mat.

Parameter followed for biodegradation estimation:

O2 consumption

Details on study design:

Water: The water used during this study is deionised water containing less than 10 mg/l dissolved organic carbon.
Mineral medium: Mineral medium was prepared by mixing previously prepared solutions A, B, C and D. The pH was measured and, if necessary, adjusted to 7.4 ± 0.2 with phosphoric acid or potassium hydroxide.
Preparation of sludge: The sludge was collected in the morning, washed three times in the mineral medium (by centrifuging at 1000 g for 10 minute, discarding the supernatant and resuspending in mineral medium) and kept aerobic until being used on the same day.
Actvated sludge: Dry weight of suspended solids was 8.02 g/l, diluted to 1.53 g/l.
Dry weight determination: The dry weight of suspended solids was determined by taking two 50 ml samples of homogenized sludge, evaporating water on the steam bath, drying in an oven at 105 - 110°C for two hours and weighing the residue.
Preparation of flasks: Flasks are filled with 250 ml mineral medium and by adding the test solution or reference substance.
Performance of the test: Everyday the oxygen consumption of each flask was recorded and correct temperature and stirring are checked. During the test performance and at the end of the test peroid, the pH of each flask was measured.
Temperature: Test temperature was kept at the level of 21.4 - 22.3°C.

Some changes were incorporated to study plan compared with the guidelines. An optional toxicity control was not performed. The test substance concentration was 30 mg/l instead of 100 mg/l. Though, the validity of the study was not adversely affected.

Reference substance:

benzoic acid, sodium salt

Key result

Parameter:

% degradation (O2 consumption)

Value:

81

Sampling time:

28 d

Details on results:

The 10-day window criterion was also fulfilled (12% biodegradation on day 5 and 64% on day 15).

Results with reference substance:

Degradation of sodium benzoate exceeded 40% after 7 days and 65% after 14 days, and on day 28 it reached 93%.

Validity criteria fulfilled:

yes

Remarks:

Degradation of the reference substance was proper and the repeatability validity criterion (not more than 20% difference between replicates) was fulfilled for the flasks containing test substance. Therefore, the test was considered valid.

Interpretation of results:

readily biodegradable

Conclusions:

The substance showed 81% biodegradation in an OECD TG 301F test and is considered readily biodegradable (with the 10-day window criterion fulfilled).

Executive summary:

The ready biodegradability of Beta-pinene was investigated in a study conducted in accordance with OECD TG 301F (Manometric Respirometry Test) and GLP. The concentration tested was 30 mg/l test substance, with an activated sludge concentration of 1.53 mg/l. The test substance biodegraded for 81% and it was not toxic to the inoculum (93% biodegradation of the reference substance sodium benzoate). The 10-day window criterion was fulfilled. The substance is considered to be readily biodegradable.

Reference 2

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

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

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Information derived from read across

Justification for type of information:

The full read-across document can be found in the Endpoint Summary in text and in the attached file.

Reason / purpose for cross-reference:

read-across source

Key result

Parameter:

% degradation (O2 consumption)

Value:

81

Sampling time:

28 d

Remarks on result:

other: readily biodegradable

Validity criteria fulfilled:

yes

Remarks:

adequate and reliable documentation on the read across is provided

Interpretation of results:

readily biodegradable

Conclusions:

The percentage biodegradation for the substance is 81% and therefore results in readily biodegradable based on the read across from Beta-pinene (tested in an OECD TG 301F).

Description of key information

Biodegradation (read-across from Beta-pinene (CAS number 127-91-3)): readily biodegradable.

Key value for chemical safety assessment

Biodegradation in water:

readily biodegradable

Additional information

Biodegradation is based on read across from Beta-pinene (CAS number 127-91-3). First the study with the analogue is described and thereafter the read across justification is presented.

The ready biodegradability of Beta-pinene was investigated in a study conducted in accordance with OECD TG 301F (Manometric Respirometry Test) and GLP. The concentration tested was 30 mg/l test substance, with an activated sludge concentration of 1.53 mg/l. The test substance biodegraded for 81% and it was not toxic to the inoculum (93% biodegradation of the reference substance sodium benzoate). The 10-day window criterion was fulfilled. The substance is considered to be readily biodegradable.

Rosemarel and its ready biodegradability in water sediment using read across information from Beta-pinene (CAS number127-91-3).

 

Introduction and hypothesis for the analogue approach

Rosemarel is a multi-constituent. The major part is the constituent Beta-pinene (51%) and this constituent has a hexyl ring bridged with one carbon, to which two methyl groups are attached. At the alpha position there is a double bonded methyl group attached to the hexyl ring, which is the functional group. The minor constituent (36%) has the same backbone. The functional group is an epoxide in the place where there is the double bonded methyl group in the other component. For Rosemarel data on ready biodegradation are lacking.

In accordance with Article 13 of REACH, lacking information should be generated whenever possible by means of applying alternative methods such as in vitro tests, QSARs, grouping and read-across. For assessing the ready biodegradation of the substance in water - sediment the analogue approach is selected because for one closely related analogue a reliable ready biodegradability study is available which can be used for read across.

Hypothesis: Rosemarel is expected to have similar biodegradation as Beta-pinene because its major constituent is Beta-pinene and its minor constituent is the oxidized Beta-pinene.

Available experimental information: For an analogue, Beta-pinene, data are available from an OECD 301F test (Givaudan, 2012; GLP, K1). It was biodegraded by 81% after 28 days, meeting the 10-day window criteria, which results in the substance being readily biodegradable.

Target chemical and source chemical(s)

The target is Rosemarel, and the source is Beta-pinene. Chemical structures of the target chemical and the source chemical are shown in the data matrix below. Also physico-chemical properties thought to be relevant for biodegradation are listed in there. 

 

Purity / Impurities

Rosemarel consists of Beta-pinene (51%) and its oxidised form- the epoxide (36%). 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.

 

Analogue selection:

Beta-pinene was selected as an analogue because it is Rosemarel’s major constituent, and when it is oxidised, Beta-pinene becomes Rosemarel’s minor constituent.

Structural similarities and dissimilarities:

Rosemarel contains 51% Beta-pinene and thus the overlap between the analogues is already 51%. The epoxide constituent has the same backbone as Beta-pinene but the double bond is oxidized into the epoxide component of Rosemarel.

Bioavailability:

The bioavailability of both Rosemarel and Beta-pinene is the same considering physico-chemical properties. Beta-pinene has a higher log Kow and lower water solubility as can be expected without additional oxygen of the epoxide constituent. 

Biodegradability:

The first step in degradation will be the oxidation of the Beta-pinene double bond. From there on, the biodegradability steps will be the same.

Uncertainty of the prediction:

There is no remaining uncertainty. This is further supported by the EPI Suite prediction (BIOWIN5 = 0.5, BIOWIN6 = 0.39 for Rosemarel and BIOWIN5 = 0.47, BIOWIN6 = 0.39 for Beta-pinene).

Conclusions on the ready biodegradability of Rosemarel

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. Beta-pinene is readily biodegradable (OECD TG 301F) and this information is reliable and can be used for the read-across for Rosemarel. Therefore, also Rosemarel is readily biodegradable.

Final conclusion on ready biodegradability: Rosemarel is readily biodegradable.

 

Data matrix for Rosemarel and Beta-pinene to document read across for ready biodegradation.

 

Name of substance	Rosemarel and its two constituents: Beta-pinene and its oxidation product	Beta-pinene
Chemical structure
Empirical	C10H16 and C10H16O	C10H16
Cas No	127-91-3 and 6931-54-0, respectively	127-91-3
REACH registration	To be registered for 2018	Registered
Mol weight	136.24 and 152.24	136.24
Phys-chem
Appearance	Colourless to slight yellow liquid (IFF, 2016)	Liquid
Melting point(^oC)	<-20 (IFF, 2016)	-20 (ECHA site)
Boiling point (^oC)	173.85 (C) 172.2 (IFF, 2016)	150.80 (C) 166-179 (ECHA site)
Vapour pressure (Pa at 25^oC)	345.9 (IFF, 2016)	851 (ECHA site)
Water solubility (mg/l)	7.1 and 338 (C) 45.7 (IFF, 2016)	7.1 (C) 6.95 (ECHA site)
Log Kow	4.35 and 2.95 (C) 3.2-3.4 (IFF, 2016)	4.35 (C) 4.4 (ECHA site)
Biodegradation %	Read across from Beta-pinene	Readily biodegradable (Givaudan, 2012)
EPISUITE prediction	EPISUITE prediction: BIOWIN5 = 0.5, BIOWIN6 = 0.39	EPISUITE prediction: BIOWIN5 = 0.47, BIOWIN6 = 0.39

C: calculated value, the physico-chemical data were generated with EPISuite (version 4.1).