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Biodegradation in water: screening tests

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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: read-across from a guideline study
Justification for type of information:
The read across rationale is presented in the related Endpoint summary, the accompanying files are also attached there.
Reason / purpose for cross-reference:
read-across source
Key result
Parameter:
% degradation (O2 consumption)
Value:
79
Sampling time:
28 d
Remarks on result:
other: read-across from Myrcenyl acetate
Validity criteria fulfilled:
yes
Interpretation of results:
readily biodegradable
Endpoint:
biodegradation in water: ready biodegradability
Type of information:
experimental study
Adequacy of study:
key study
Study period:
1999-11-18 to 1999-12-17
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Justification for type of information:
The information is used for read across to Pseudo linalyl acetate.
Qualifier:
according to guideline
Guideline:
OECD Guideline 301 F (Ready Biodegradability: Manometric Respirometry Test)
Version / remarks:
1992
GLP compliance:
yes
Oxygen conditions:
not specified
Inoculum or test system:
activated sludge, domestic, non-adapted
Details on inoculum:
- Source of inoculum/activated sludge: Fresh activated sludge from a biological waste water treatment plant treating predominantly domestic sewage (City of Geneva, Aire) was used.
- 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.
- Determination of the dry weight of suspended solids: The dry weight of suspended solids is determined by taking two 50 mL samples of the homogenised sludge, evaporating water on a steam bath, drying in an oven at 105 - 110 oC for two hours and weighing the residue.
- Dry weight of suspended solids: 3.289 g/L
Duration of test (contact time):
28 d
Initial conc.:
100 mg/L
Based on:
test mat.
Parameter followed for biodegradation estimation:
O2 consumption
Details on study design:
TEST CONDITIONS
- Water used during this study is deionised water containing less than 10 mg/L dissolved organic carbon.
- Composition of medium: Stock solutions of mineral components (solution A, B, C, D) were prepared according to the guideline. Mineral medium is prepared by mixing 50 mL of solution A and 2000 mL deionised water, adding 5 mL of each of the solutions B, C and D and making up to 5 litres with deionised water. The pH is measured and if necessary adjusted to 7.4 +/- 0.2 with phosphoric acid or potassium hydroxide.
- Test temperature: 22 oC
- pH: 7.4 (at initiation)
- Activated sludge: to obtain a concentration of 30 mg/L (dry weight) in a 250 mL flask, 2.28 mL of sludge (dry weight of suspended solids: 3.289 g/L) is needed (inoculum).

TEST SYSTEM
- Culturing apparatus: Respirometer, SAPROMAT D12, made by J. M. VOITH GmbH, Heidenheim, Germany.
- Number of culture flasks/concentration: 2/test suspension, 2/procedure control, 2/inoculum blank, 2/toxicity control
- Measuring equipment: SAPROMAT meter
- Details of trap for CO2 if used: about 2 g soda lime is placed in an attachment of the stopper of 250-mL flasks.

CONTROL AND BLANK SYSTEM
- Inoculum blank: yes
- Abiotic sterile control: no
- Toxicity control: Yes, the toxicity of the test chemical for the inoculum is checked. Therefore, a pair of flasks of the volumetric respirometer are filled with mineral medium + test chemical (100 mg/L) + reference substance (100 mg/L) + inoculum and their respirations are recorded as for the other flasks. If they are lower than those of the flasks containing mineral medium + referenc substance (100 mg/L) + incoculum, the test chemical can be assumed to be inhibitory to the inoculum used.

RESULTS
Oxygen uptakes, as read on the SAPROMAT meters, are corrected:
- by deducting the basic oxygen uptake of sludge
- proportionally to account for the small differences between actual and nominal concentrations of test and reference substances
Means of identical flasks were used to obtain the different results and curves.
Reference substance:
other: Sodium Benzoate (Purity: min. 99.0%)
Remarks:
Test concentration: 100 mg/L
Test performance:
Final pH values are all surprisingly high (7.93 -9.36). This suggests more a misfunctioning of the pH meter than an unusual behaviour of the test solutions. The test results were not affected.
Key result
Parameter:
% degradation (O2 consumption)
Value:
79
Sampling time:
28 d
Remarks on result:
other: Biodegradation starts on day 3 and reaches 61% at the end of the 10-day window (days 3 to 13).
Details on results:
The test substance undergoes 79% biodegradation after 28 days in the test conditions. Biodegradation starts on day 3 and reaches 61% at the end of the 10-day window (days 3 to 13), just meeting the 10-day window. Thus the test substance should be regarded as readily biodegradable according to this test.
Results with reference substance:
Degradation of sodium benzoate exceeds 40% after 7 days and 65% after 14 days, the activity of the inoculum is thus verified and the test is considered as valid.

Biological Oxygen Demand (BOD, mg O2/L, adjusted to nominal concentrations):

 

 

Days:

3

7

13

14

21

28

BOD Sludge

1rst flask

B1

6.0

16.0

16.0

17.0

19.0

21.0

 

2nd flask

B2

6.0

16.0

16.0

18.0

21.0

21.0

 

mean

B

6.0

16.0

16.0

17.5

20.0

21.0

BOD Test substance

1rst flask

C1

63.2

129.4

180.8

182.8

207.7

240.1

 

2nd flask

C2

59.9

116.2

168.2

174.1

189.6

214.6

 

1rst fl. Corr.

C1-B

57.2

113.4

164.8

165.3

187.7

219.1

 

2nd fl. Corr.

C2-B

53.9

100.2

152.2

156.6

169.6

193.6

% Degr.

1rst flask

D1

22

43

63

63

72

84

 

2nd flask

D2

21

38

58

60

65

74

 

mean

D

21

41

61

62

68

79

The curves obtained with the reference substance alone and with the test substance + reference substance show no toxic effect of the test substance to the micro-organisms at the test concentration.

Validity criteria fulfilled:
yes
Interpretation of results:
readily biodegradable
Conclusions:
The substance is biodegraded by 79% after 28 days in the manometric respirometry test (OECD TG 301F). Biodegradation starts on day 3 and reaches 61% at the end of the 10-day window (days 3 to 13), just meeting the 10-day window criteria. Thus the substance should be classified as readily biodegradable according to this test.
Executive summary:

Ready biodegradability of the test substance is tested in the Manometric Respirometry Test, according to OECD 301F and in accordance with GLP. Fresh activated sludge form a biological waste water treatment plant treating predominantly domestic sewage (City of Geneva, Aïre) was used. Test substance was tested at 100 mg/L in 250 mL test flasks of the SAPROMAT respirometer, filled with 250 mL of mineral medium. A volume of suspended sludge is added, 2.28 mL sludge (dry weight of suspended solids is 3.289 g/L) is needed, corresponding to a concentration of 30 mg/L (dry weight). About 2 g of soda lime is placed in an attachment of the stopper, the flasks are closed and placed in the water bath. The test substance undergoes 79% biodegradation after 28 days in the test conditions. Biodegradation starts on day 3 and reaches 61% at the end of the 10-day window, just meeting the 10-day window criteria. Thus the test substance should be classified as readily biodegradable according to this test. Degradation of reference substance, Sodium Benzoate, exceeds 40% after 7 days and 65% after 14 days: the activity of the inoculum is thus verified and the test is considered as valid. No toxic effect of the test substance to the micro-organisms was observed at test concentration.

Description of key information

Pseudo Linalyl Acetate is readily biodegradable based on read across from Myrcenyl acetate 'mono', which was tested in 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 Myrcenyl Acetate to Pseudo Linalyl Acetate. The executive summary of the source information is presented below, followed by the read-across rationale.

Myrcenyl acetate 'mono' biodegradation information

The ready biodegradability is tested in the Manometric Respirometry Test, according to OECD 301F and in accordance with GLP. Fresh activated sludge form a biological waste water treatment plant treating predominantly domestic sewage (City of Geneva, Aïre) was used. Test substance was tested at 100 mg/L in 250 mL test flasks of the SAPROMAT respirometer, filled with 250 mL of mineral medium. A volume of suspended sludge is added, 2.28 mL sludge (dry weight of suspended solids is 3.289 g/L) is needed, corresponding to a concentration of 30 mg/L (dry weight). About 2 g of soda lime is placed in an attachment of the stopper, the flasks are closed and placed in the water bath. The test substance undergoes 79% biodegradation after 28 days in the test conditions. Biodegradation starts on day 3 and reaches 61% at the end of the 10-day window, just meeting the 10-day window criteria. Thus the test substance should be classified as readily biodegradable according to this test. Degradation of reference substance, Sodium Benzoate, exceeds 40% after 7 days and 65% after 14 days: the activity of the inoculum is thus verified and the test is considered as valid. No toxic effect of the test substance to the micro-organisms was observed at test concentration.

Biodegradation of Pseudo linalyl acetate based on read across from data available for Myrcenyl acetate (CAS# 1118-39-4).

 

Introduction and hypothesis for the analogue approach

Pseudo linalyl acetate has one major, two minor constituent and several impurities (< 10%) and is a multi-constituent. Myrcenyl acetate is the main constituent. For Pseudo linalyl acetate 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 biodegradation of Pseudo linalyl acetate, the analogue approach is selected because for the main constituents, Myrcenyl and Alpha-Terpinyl acetate, experimental data is available which can be used for read across.

Hypothesis: Pseudo linalyl acetate is readily biodegradable because two of its constituents arereadily biodegradable. The other constiutents and impurities are calculatied to be readily biodegradable. 

Available information:For Myrcenyl acetate experimental test result is available from a Manometric Respirometry test according to OECD TG 301F (Manometric Respirometry Test) and in compliance with GLP. In this study, 100 mg/L of the test substance was inoculated with activated sludge from a predominantly domestic sewage treatment plant, for 28 days. The substance was biodegraded by 79% after 28 days. Biodegradation started on day 3 and reached 61% at the end of the 10-day window (days 3 to 13). Based on these findings, the substance is qualified as readily biodegradable. The data is assignedreliable without restrictions (Klimisch 1).

Target chemical and source chemical(s)

Chemical structures of the target chemical and the source chemical(s) are shown in the data matrix, including physico-chemical properties and available environmentalfateinformation.

Purity / Impurities

Pseudo linalyl acetate does not 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. 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: Myrcenyl acetate ‘mono’ was selected as the key analogue because it is the major constituent and expected to sufficiently represent the other components.

Structural similarities and differences: Pseudo linalyl acetate constituents all have a hydrocarbon backbone with one or more (non-) conjugated double bonds. This backbone can be either linear or can contain a single alicyclic ring structure. All constituents are acetic esters. All constituents are multi-methylated with 2 to 4 methyl groups at varying positions. The difference is that some have a conjugated double bond, Myrcenyl acetate ‘mono’ being one of them, which are more electrophilic (reactive).

Bioavailability: Pseudo linyl acetate’s constituents and Myrcenyl acetate ‘mono’ have similar bioavailability with molecular weight around 200 and log Kow 4.4, which will not make a difference for the ready biodegradable potential.

Biodegradable fragments: In the BIOWIN 5 and 6 modules, linear fragments have a slightly higher potential to be biodegraded than cyclic structural fragments. The number of the methyl groups or the number of the double bonds has no significant effect on the biodegradation prediction. The most important difference with respect to BIOWIN predicted values is the presence of the ester versus the alcohol functional group of which the adds to the biodegradation. Only the 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.

BIOWIN predictions: BIOWIN (v4.10) predictions are made for all different constituents of Pseudo linalyl acetate to provide further insight into the biodegradation potential of these constituents.

 

Table: summary of BIOWIN predicted data for all constituents of Pseudo linalyl acetate

CAS#

Type of constituent

Type and Name

BIOWIN5

BIOWIN6

 

 

Esters linear and alicyclic

 

 

1118-39-4

Major

2-methyl-6-methylideneoct-7-en-2-yl acetate

(Myrcenyl acetate)

0.7200

0.7674

7643-61-0

Impurity

(5Z)-2,6-dimethylocta-5,7-dien-2-yl acetate

0.6648

0.6802

7643-62-1

Impurity

(5Z)-2,6-dimethylocta-5,7-dien-2-yl acetate

0.6648

0.6802

105-87-3 *

Impurity

(2E)-3,7-dimethylocta-2,6-dien-1-yl acetate

(Geranyl acetate)

(Ready biodegradable based on testing)

0.6342

0.6744

80-26-2 *

Minor

2-(4-methylcyclohex-3-en-1-yl)propan-2-yl acetate (Alpha-Terpinyl acetate)

0.6190

0.5964

150461-96-4

Impurity

1-(3,3-dimethylcyclohex-1-en-1-yl)ethyl acetate

0.5559

0.6035

150461-97-5

Impurity

1-(5,5-dimethylcyclohex-1-en-1-yl)ethyl acetate

0.5559

0.6035

10235-63-9

Minor

1-methyl-4-(propan-2-ylidene) cyclohexyl acetate (Gamma-Terpinyl acetate)

0.6201

0.6743

20777-47-3

Impurity

cis-1-methyl-4-(prop-1-en-2-yl)cyclohexyl acetate (Beta-Terpinyl acetate)

0.6445

0.6539

97890-05-6

Impurity

(2Z)-2-(3,3-dimethylcyclohexylidene)ethyl acetate

0.6753

0.7625

76-49-3

Impurity

(1R,2S,4R)-1,7,7-trimethylbicyclo[2.2.1]hept-2-ylrel-acetate (Bornyl acetate)

0.6929

0.6528

210648-12-7

Impurity

3,3,5-trimethylcyclohept-4-en-1-yl acetate

0.6190

0.5964

 

 

Alcohol linear and alicyclic

 

 

543-39-5

Impurity

2-methyl-6-methylideneoct-7-en-2-ol

(Myrcenol)

0.5009

0.4854

98-55-5 *

Impurity

2-(4-methylcyclohex-3-en-1-yl)propan-2-ol

(Alpha-terpineol)

(Readily biodegradable based on testing)

0.3999

0.2970

586-81-2

Minor

1-methyl-4-(propan-2-ylidene)cyclohexanol

(Gamma-terpineol)

0.4010

0.3719

* These substances are reported to be readily biodegradable on the ECHA website (disseminated data).

 

BIOWIN scores for all ester constituents are well above 0.5 and therefore these constituents are predicted to be readily biodegradable. This is substantiated by data available for 3 different constituents belonging to this sub-group, Myrcenyl acetate, Geranyl acetate (ECHA disseminated data) and Alpha-Terpinyl acetate (ECHA disseminated data), which were all experimentally determined to be readily biodegradable.

With respect to the alcohols, with predicted biodegradation scores of <0.5, these constituents are predicted to be borderline or not readily biodegradable. However, the major impurity is Alpha-Terpineol, which has been experimentally determined to be readily biodegradable in a study according to OECD TG 310 (ECHA website) and therefore these other alcohols are not expected to impact the ready biodegradability of the overall substance.

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

Data matrix

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

Conclusions for biodegradation

For Pseudo linalyl acetate as such no biodegradability information is available but for several constituents such data are presented. Myrcenyl acetate being the major constituent of Pseudo linalyl acetated is used as an analogue and its biodegradation information is used for read across. When using read across, the information should be presented with adequate and reliable documentation, which is presented in the current document. Myrcenyl acetate is readily biodegradable in an OECDTG 301D test and therefore also Pseudo linalyl acetate is readily biodegradable.

Final conclusion on ready biodegradability: Pseudo linalyl acetate is readily biodegradable.

 

Data matrix supporting the read across to Pseudo linalyl acetate from Myrcenyl acetate ‘mono’ for biodegradation

Common name

Pseudo linalyl acetate

Myrcenyl acetate ‘mono’

Alpha-Terpinyl acetate

Gamma-terpinyl acetate

 

Target

Source (Major constituent)

Supporting source

(Minor constituent)

Minor constituent

Structure

 

 

CAS #

--

1118-39-4

80-26-2

10235-63-9

EC #

--

214-262-0

201-265-7

233-564-3

Reach registration

2018

2018

Registered

Not found

Empirical formula

n.a.

C12H20O2

C12H20O2

C12H20O2

SMILES

n.a.

CC(=O)OC(C)(C)CCCC(=C)C=C

O=C(OC(C(CCC(=C1)C)C1)(C)C)C

O=C(OC(CCC(=C(C)C)C1)(C1)C)C

Molecular weight

n.a.

196

196

196

Physico-chemical data

 

 

 

 

Log Kow

4.4

4.4 (exp.)

4.3

4.5

Environmental fate

 

 

 

 

Biodegradation

Readily biodegradable

(Read across)

Readily biodegradable

(OECD TG 301F)

Readily biodegradable

(OECD TG 301F)

Readily biodegradable

(Read across)