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Biodegradation in water: screening tests

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Endpoint:
biodegradation in water: ready biodegradability
Type of information:
experimental study
Adequacy of study:
weight of evidence
Study period:
Not specified
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
study well documented, meets generally accepted scientific principles, acceptable for assessment
Remarks:
The article is a summary of biodegradation tests done at Givaudan laboratories according to the guideline OECDTG301F. Studies should be done the same way for proper comparison of test substance results, hence the test for Cedrol (indicated as done prior to the majority of substances) is likely perfomed as indicated in materials and methods. It is therefore anticipated to be fully compliant for regulatory purposes.
Reference:
Composition 0
Qualifier:
according to
Guideline:
OECD Guideline 301 F (Ready Biodegradability: Manometric Respirometry Test)
GLP compliance:
not specified
Remarks:
Done according to OECD guideline TG301F but not specified to be GLP compliant
Test material information:
Composition 1
Oxygen conditions:
aerobic
Inoculum or test system:
sewage, domestic (adaptation not specified)
Details on inoculum:
Fresh activated sludge from a biological wastewater treatment plant treating predominantly domestic sewage was used. The sludge was collected in the morning, washed three times in the mineral medium (by centrifuging at 1000 g for 10 min, discarding the supernatant and resuspending in mineral medium) and kept aerobic until being used on the same day. The dry weight of suspended solids was determined by taking two 50-ml samples of the homogenized sludge, evaporating water on a steam bath, drying in an oven at 1058°C to 1108°C for 2 h and weighing the residue.
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
- Composition of medium: A mineral medium as described in the OECD 301 Guideline was prepared.
- Test temperature: not specified
- pH: Because of the low solubility of the test substances and in order not to remove any floating undissolved test substance from the test medium by dipping a glass electrode in it, the pH of each flask was not measured but assumed to be the same as the mineral medium. At the end of the test period, the pH of each flask was measured and found to be in the range of pH 7.4 to 7.7 for all test substance flasks.
- pH adjusted: yes: The pH was measured and if necessary adjusted to 7.4 +/- 0.2 with phosphoric acid or potassium hydroxide.

TEST SYSTEM
- Culturing apparatus: 250ml flask
- Number of culture flasks/concentration: carried out in duplicates
- Measuring equipment: The respirometers used during the present study were Sapromat1 D 12, made by J. M. Voith. Glass capillaries were introduced between the test flasks (500 ml nominal volume) and the oxygen generators to limit losses of the volatile test substance.
Other: All flasks were filled with 250 ml of mineral medium. Samples of test or reference substance, or both in the case of the toxicity control, were added. Then, a volume of suspended sludge corresponding to 30 mg/L dry weight (as determined) was added.

SAMPLING
- Sampling frequency: Daily
- Sampling method: Oxygen consumption of each flask was recorded and correct temperature and stirring were checked.

CONTROL AND BLANK SYSTEM
- Toxicity control: toxicity of the test substance for the inoculum was checked by testing a mixture of test substance (100 mg/L) and reference substance (100 mg/L) (i.e., both at the same test concentration as in the individual solutions). If the respirations in the toxicity control are lower than those of the flasks containing mineral medium, reference substance (100 mg/L), and inoculum, the test substance can be assumed to be inhibitory to the inoculum used.
- Other:
Reference substance:
benzoic acid, sodium salt
Remarks:
>99%
Key result
Parameter:
% degradation (O2 consumption)
Value:
88
Sampling time:
28 d
Results with reference substance:
The reference compound showed a high percentage of biodegradability (> 85%), confirming the viability of the inoculum.
Validity criteria fulfilled:
not specified
Interpretation of results:
readily biodegradable
Conclusions:
Cedrol was biodegraded by 88% at day 28. The substance should therefore be classified as readily biodegradable.
Executive summary:

In order to assess the biodegradation of multiple sesquiterpene structures including Cedrol, screening tests were performed according to OECD TG 301F (Manometric Respiratory test). In this article where biodegradation is compared for 11 substances, activated sludge from a biological wastewater treatment plant treating predominantly domestic sewage, was exposed to 100 mg/L of the substance for 28 days. The reference substance showed a high percentage of biodegradability (> 85%) and no toxic effects to microorganisms. While validity checks cannot be confirmed due to the lack of raw data, the article is based on a number of OECDTG301F guideline studies and are considered to fulfill its validity criteria. It is reported that 88% of Cedrol is biodegraded at day 28 and therefore can be classified as readily biodegradable.

Endpoint:
biodegradation in water: ready biodegradability
Type of information:
other: Known constituent approach
Adequacy of study:
weight of evidence
Study period:
May 2018
Reliability:
4 (not assignable)
Rationale for reliability incl. deficiencies:
other: constituent approach
Remarks:
An assessment of biodegradation of the UVCB was made on relevant information per constituent, not following a specific methodology.
Justification for type of information:
No test result on the biodegradation of the NCS/UVCB Cedarwood Himalayan oil (cas no. 91771-47-0) is available. According to the NCS Protocol (The Registration for REACH of Natural Complex Substances used as Fragrance Ingredients Revision 2, January 7, 2009 and EFEO/IFRA Guidelines on the Environmental Assessment of Natural Complex Substances (NCS) Version 01, May 26, 2016), the assessment of the biodegradability of a NCS can be based on a constituent approach.
Reference:
Composition 0
Qualifier:
according to
Guideline:
OECD Guideline 301 D (Ready Biodegradability: Closed Bottle Test)
Qualifier:
according to
Guideline:
OECD Guideline 301 F (Ready Biodegradability: Manometric Respirometry Test)
Principles of method if other than guideline:
Assessment of the ready biodegradability of the known constituents: addition of the percentage of readily biodegradable constituents in the mixture gives the fraction of readily biodegradable substances.
GLP compliance:
no
Test material information:
Composition 1
Specific details on test material used for the study:
Assessment of constituents was based on using CAS numbers and molecular structures for identification.
Oxygen conditions:
aerobic
Inoculum or test system:
mixture of sewage, soil and natural water
Remarks:
several guideline tests with different inocula were used
Duration of test (contact time):
>= 28 - <= 60 d
Parameter followed for biodegradation estimation:
O2 consumption
Key result
Parameter:
% degradation (O2 consumption)
Value:
>= 60
Sampling time:
28 d
Remarks on result:
other: Constituent 1, 6, 7, 8, 10 and 11
Key result
Parameter:
% degradation (O2 consumption)
Value:
>= 60
Sampling time:
60 d
Remarks on result:
other: Constituent 2, 3, 4, 5 and 9
Remarks:
sampling time =>60 days

Constituents of Cedarwood oil Himalayan and assessment of biodegradation

Constituent

w/w % in UVCB

Cas no

Smiles

Structure

Group for comparison

Remarks and references

1

50-70

77-53-2 (Cedrol)

C[C@@H]1CC[C@@H]2[C@]13CC[C@@]([C@H](C3)C2(C)C)(C)O

Cedrane

Cedrol: readily biodegradable (Jenner et al, 2011 (TG301F)).

 

In support, Cedarwood Texas Cedrol (with a Cedrol concentration of > 50%) is concluded also readily biodegadable, (ref. REACH dossier (TG301D)).

2

1-8

65700-78-9

(Hydrolized Cadinene 1)

[H][C@@]12C=C(C)CC[C@@]1([H])[C@](C)(O)CC[C@H]2C(C)C

 

Cadinene

d-Cadinene: inherently and ultimately biodegradable (Jenner et al, 2011(TG301F)).

 

Cadinene isomers are also present in

- Gurjun Balsam Copaene (~10%)

- Copaiba Balsam (~3%)

 -Ylang Ylang III (~3.5%)

All these UVCBs are readily biodegadable, (ref. REACH dossier (TG301D)).

This constituent is therefore anticipated at least inherently and ultimately biodegradable.

3

1-5

86023-67-8

(Hydrolized Cadinene 2)

[H][C@]12CC(C)=CC[C@@]1(O)[C@@H](C)CC[C@@H]2C(C)C

Cadinene

Anticipated to be at least inherently and ultimately biodegradable. See constituent 2.

4

0.5-4

159990-04-2

(Hydrolized Cadinene 3)

[H][C@]12C=C(C)CC[C@@]1(O)[C@H](C)CC[C@@H]2C(C)C

Cadinene

Anticipated to be at least inherently and ultimately biodegradable. See constituent 2.

5

0-3

57440-66-1

(Hydrolized Cadinene 4)

CC(C)C1CCC(C)=C2CCC(C)(O)CC12

Cadinene

Anticipated to be at least inherently and ultimately biodegradable. See constituent 2.

6

1-8

159517-24-5

[H][C@@]12CC[C@@H](C)[C@]11CC[C@@](C)([C@@H](O)C1)C2(C)C

 

Cedrane analogue

The structure is an analogue to the Cedrane group (ref. A fragrant introduction to terpenoid chemistry, by C. Sell, chapter Biosynthesis, page 31).Anticipated to be readily biodegradable. See constituent 1.

7

1-7

114674-10-1

[H][C@@]12[C@@H](O)C[C@@H](C)[C@]11C[C@@H](C(=C)CC1)C2(C)C

Cedrane

Structure is similar to beta biotol & cedrenol.

The constituent is a hydroxylated cedrane derivative. Jenner et al. (2011) showed that both alpha cedrene and cedrol are readily biodegradable in TG301F. This constituent is therefore anticipated to be readily biodegradable too.

8

1-5

38108-86-0

[H][C@]12[C@H](O)[C@H](CC[C@]1(C)CCCC2=C)C(C)C

Eudesmene

Eudesmole isomers are common in Amyris oil (individually ~5-14%, sum ~43%) and Guaiacwood oil (sum ~16%), both are concluded to be readily biodegradable (ref. REACH dossier (TG301D)). This constituent is therefore anticipated to be readily biodegradable.

9

1-7

126999-77-7

[H][C@]12CCC(C)C[C@@]1([H])C(C)(C)CCC[C@]2(C)O

Himachalene

Structure is similar to Himachalol (cas no. 1891-45-8). Himachalene isomers are present in Cedarwood Atlas oil (range of individual isomers~ 10-50%, sum ~80%). This oil is concluded inherently and ultimately biodegradable (ref. REACH dossier (TG301D)).This constituent is anticipated not readily, but inherently and ultimately biodegradable.

10

1-10

955007-43-9

[H][C@@]1(C)CC[C@@]([H])(C(C)(C)O)[C@@]11CCC(C)=CC1

Acorane/acoradiene

The structure can be categorized as acorane/acoradiene (ref. A fragrant introduction to terpenoid chemistry, by C. Sell, chapter Biosynthesis, page 31). Gamma acoradiene is present ~2% in Cedarwood Chinese oil, which is concluded to be readily biodegradable(ref. REACH dossier (TG301D)).Consequently, the constituent is expected to be readily biodegradable.

11

0.5-4

3287-59-0

[H][C@@]12C[C@@H](CC[C@@]1(C)CCCC2=C)C(C)(C)O

Eudesmene

Beta eudesmol (cas no. 473-15-4).

See constituent 8, anticipated to be readily biodegradable.


Validity criteria fulfilled:
not applicable
Interpretation of results:
readily biodegradable
Conclusions:
Based on all the available information, Cedarwood oil Himalayan is considered not persistent. Not all constituents can be concluded to be readily biodegradable, however, these are minor constituents. Considering the concentrations of known constituents, which are anticipated readily biodegradable (≤ 84%), Cedarwood oil Himalayan could be readily biodegradable. Likewise, up to 16% of the known constituents are assessed to be inherently and ultimately biodegradable.

Executive summary:

Cedarwood oil Himalayan is a Natural Complex Substance (NCS) of which at least 85% (w/w) of the constituents are identified. An assessment of the biodegradability of Cedarwood oil Himalayan was made based on the degradability of its constituents belonging to particular sesquiterpene structure groups and the underlying assumption that if the constituents of the NCS are readily biodegradable, the NCS itself should also be readily biodegradable. Data on constituents were either derived from experimental or non-testing data to asses biodegradability. Based on all the available information, Cedarwood oil Himalayan is considered not persistent. Not all constituents can be concluded to be readily biodegradable, however, these are minor constituents. Considering the concentrations of known constituents, which are anticipated readily biodegradable (≤ 84%), Cedarwood oil Himalayan could be readily biodegradable. Likewise, up to 16% of the known constituents are assessed to be inherently and ultimately biodegradable.

Description of key information

Cedarwood oil Himalayan is a Natural Complex Substance (NCS) of which at least 85% (w/w) of the constituents are identified. An assessment of the biodegradability of Cedarwood oil Himalayan was made based on the degradability of its constituents belonging to particular sesquiterpene structure groups and the underlying assumption that if the constituents of the NCS are readily biodegradable, the NCS itself should also be readily biodegradable. Data on constituents were either derived from experimental or non-testing data to asses biodegradability. Based on all the available information, Cedarwood oil Himalayan is considered not persistent. Not all constituents can be concluded to be readily biodegradable, however, these are minor constituents. Considering the concentrations of known constituents, which are anticipated readily biodegradable (≤ 84%), Cedarwood oil Himalayan could be readily biodegradable. Likewise, up to 16% of the known constituents are assessed to be inherently and ultimately biodegradable.

Key value for chemical safety assessment

Biodegradation in water:
readily biodegradable
Type of water:
freshwater

Additional information