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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 justification is presented in the Endpoint summary Biodegradation in water. The accompanying files are also attached there.
Reason / purpose:
read-across source
Key result
Parameter:
% degradation (inorg. C analysis)
Value:
80
Sampling time:
28 d
Remarks on result:
other: read-across from Terpineol multi
Interpretation of results:
readily biodegradable
Endpoint:
biodegradation in water: ready biodegradability
Type of information:
experimental study
Adequacy of study:
key study
Study period:
From July 24 to August 29, 2007
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
guideline study with acceptable restrictions
Remarks:
incomplete certificate of analysis of the test substance; CO2 in the headspace was not measured.
Justification for type of information:
This information is used for read-across to the Terpene hydrocarbon alcohols.
Qualifier:
according to
Guideline:
OECD Guideline 310 (Ready Biodegradability - CO2 in Sealed Vessels (Headspace Test)
Deviations:
yes
Remarks:
incomplete certificate of analysis of the test substance; CO2 in the headspace was not measured
GLP compliance:
yes (incl. certificate)
Oxygen conditions:
aerobic
Inoculum or test system:
activated sludge, domestic, non-adapted
Details on inoculum:
- Source of secondary activated sludge: Activated sludge plant treating predominantly domestic waste water (WWTP Nieuwgraaf, Duiven, The Netherlands)
- Preconditioning: 400 mg Dry Weight (DW)/L of activated sludge was aerated overnight and then diluted to a concentration of 4 mg DW/L in the test vessels
- Concentration of sludge: 400 mg DW/L
Duration of test (contact time):
28 d
Initial conc.:
25.7 mg/L
Based on:
test mat.
Initial conc.:
20 mg/L
Based on:
DOC
Parameter followed for biodegradation estimation:
inorg. C analysis
Details on study design:
TEST CONDITIONS
- Composition of medium: Nutrient medium contained per liter of deionised water: 85 mg KH2PO4, 217.5 mg K2HPO4, 334 mg Na2HPO4.2H2O, 5 mg NH4CI, 22.5 mg MgSO4.7H2O, 27.5 mg CaCI2, 0.25 mg FeCI3.6H2O
- Source/preparation of dilution water: Deionised water containing < 1 mg/L of organic carbon
- Test temperature: 19-21 °C
- pH: 6.8-7.4
- Suspended solids concentration: 4 mg DW/L
- Continuous darkness: Yes
- Agitation: Incubated bottles were agitated throughout the test on a rotary shaker at 180 rpm

TEST SYSTEM
- Culturing apparatus: Serum flaks (120 mL) with butyl septa and crimp-on aluminum seals; volume of the liquid phase: 80 mL
- Number of culture flasks/concentration: 36 vessels containing only inoculum, 36 vessels containing test substance and inoculum; 9 vessels containing reference substance and inoculum

MEASURING EQUIPMENTS:
- Inorganic carbon (IC) was measured in the alkaline medium (7 M NaOH) using the TOC apparatus (Shimadzu s'Hertogenbosch, The Netherlands). Sodium carbonate and sodium bicarbonate used as control in the IC analyses.
- Chemical oxygen demand (COD) of the stock solution with the test substance was determined by oxidation with an acid-dichromate mixture in which Cr6+ was reduced to Cr3+. The subsequent increase in Cr3+ was determined spectrophotometrically at 620 nm. Potassium hydrogen phthalate used as control in the COD determination.
- pH was measured in a sample taken before the addition of NaOH using a Knick 765 calimatic pH meter (Elektronische Messgerate GmbH, Germany).
- Temperature was measured and recorded with a thermo couple connected to a data logger.

SAMPLING
- Sampling frequency: Triplicate vessels of all series were withdrawn for analyses of the carbon dioxide formed at Day 3, 7, 10, 14, 17, 21 and 28.

CONTROL AND BLANK SYSTEM
- Inoculum blank: Yes; containing inoculum only
- Procedure control: Yes; containing reference substance (sodium acetate) with inoculated medium
- Toxicity control: No; test material was considered to be non-toxic to micro-organisms as inhibition of the endogenous respiration of the inoculum was not detected during the biodegradation test.
Reference substance:
acetic acid, sodium salt
Remarks:
68.4 mg/L; Source: Acros organics, Belgium
Test performance:
The pass level of 60% was reached after approximately 10 days upon achieving 10% biodegradation. Terpineol therefore fulfilled the 10-day time window criterion for ready biodegradable compounds.
Parameter:
% degradation (inorg. C analysis)
Value:
80
Sampling time:
28 d
Details on results:
Initial test material concentration: 25.7 mg/L, representing organic carbon concentration of 20 mg/L
- Chemical oxygen demand (COD) of terpineol in the stock solution = 2.9 g/L
- Theoretical oxygen demand (ThOD) = 2.9 g/L
- Theoretical carbon content = 0.78 mg/mg
- % biodegradation on Day 5: > 10%
- % biodegradation on Day 12: > 60%
- % biodegradation on Day 28 = 80%
Results with reference substance:
- Calculated organic carbon = 0.29 mg/mg
- % biodegradation (Day 7) > 60%
- % biodegradation (Day 14) = 80%

Table 1: Inorganic carbon concentration (mg/L) in the aqueous phase (alkaline) of the test vessels

 

Time (days)

Inorganic carbon concentration (mg/L)

CLc

CLt

CLa

0

3.3

3.4

3.7

 

3.5

2.8

3.7

 

3.6

2.7

4

Mean (M)

3.5

3

3.8

3

4.5

4.5

 

 

3.6

4

 

 

4.2

4.1

 

Mean (M)

4.1

4.2

 

7

3.7

13.8

19.1

 

3.9

11.8

19.1

 

3.9

11.6

19.2

Mean (M)

3.8

12.4

19.1

10

4.9

17.6

 

 

4

14.5

 

 

4.3

14.8

 

Mean (M)

4.4

15.6

 

14

4.5

19.4

20.4

 

5

18

21.4

 

5.4

19.6

20.9

Mean (M)

5

19

20.9

17

5.6

20.6

 

 

4.7

19.9

 

 

4.7

19.7

 

Mean (M)

5

20.1

 

21

5.4

21.1

 

 

6.4

21.7

 

 

5.8

21.7

 

Mean (M)

5.9

21.5

 

28

5.7

22

 

 

5.3

21.2

 

 

6.4

21.8

 

Mean (M)

5.8

21.7

 

CLc:Mineral nutrient solution without test material but with inoculum;

CLt: Mineral nutrient solution with test material (20 mg/L organic carbon), and with inoculum;

CLa: Mineral nutrient solution with sodium acetate (20 mg/L organic carbon), and with inoculum

 

Table 2: Carbon dioxide formation (mg/L) and the percentages biodegradation of Terpineol (TIC/ThIC) and sodium acetate (TIC/ThIC) in the carbon dioxide headspace test

 

Time (days)

mg/L

Biodegradation (%)

Test

Acetate

Test

Acetate

0

 

 

0

2

3

0.1

 

1

 

7

8.6

15.3

43

77

10

11.2

 

56

 

14

14.0

15.9

70

80

17

15.1

 

76

 

21

15.6

 

78

 

28

15.9

 

80

 

Validity criteria fulfilled:
yes
Remarks:
see 'Overall remarks'
Interpretation of results:
readily biodegradable
Conclusions:
Under the test conditions, Terpineol multi was readily biodegradable.
Executive summary:

The biodegradability of Terpineol multi was investigated in a ready biodegradation study performed according to OECD TG 310 and in compliance with GLP criteria. In this study, Terpineol multi was tested at concentrations of 25.7 mg/L and the inoculum was activated sewage sludge, domestic. The degradation of the test material was assessed by the determination of the inorganic carbon concentration. The test treatments, inoculum blank and reference (sodium acetate) were measured in triplicates. At 25.7 mg/L test concentration, greater than 10% biodegradation of the test substance was reached on Day 5 and greater than 60% biodegradation was reached on Day 12. Hence, the test material met the 10 day window requirement for ready biodegradability. On Days 28, the biodegradation was 80%. The mean amount of inorganic carbon concentration in the blank control at the end of the test was greater than 3 mg C/L. The reference material, sodium acetate, reached greater than 60% biodegradation on Day 7. Terpineol was considered to be non-toxic to micro-organisms as inhibition of the endogenous respiration of the inoculum was not detected during the test. Hence, it met the validity criteria for reference material and toxicity control. Under the test conditions, Terpineol multi was readily biodegradable.

Description of key information

The Terpene hydrocarbon alcohols are readily biodegradable based on read across from Terpineol multi, which is readily biodegradable in study according to OECD TG 310.

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 Terpineol multi to Terpene hydrocarbon alcohols. The executive summary of the source information is presented below, followed by the read-across rationale.

Biodegradation of Terpene hydrocarbon alcohols based on read-across from data available for Terpineol multi (CAS# 8000-41-7).

Introduction and hypothesis for the analogue approach

Terpene hydrocarbon alcohols have the followingconstituent types of substances: Solely hydrocarbons-terpene type, Alcohol-type, Ketone-type and Ether-type all having a saturated or unsaturated cyclic hydrocarbon backbone.For this substance no biodegradation information is available. In accordance with Article 13 of REACH, lacking information can be generated by other means than experimental testing, i.e. applying alternative methods such as QSARs, grouping and read-across. For assessing the biodegradability information from the constituent Terpinolene is used, which can represent the Terpene hydrocarbon alcohols.

Hypothesis: Terpene hydrocarbon alcohols have the same biodegradability potential as Terpineol multi.

Available information: Terpineol multi is readily biodegradable in the OECD TG 310, Rel. 1 at a concentrations of 26 mg/L, 80% biodegradation was achieved, meeting the 10-day window.

Target chemical and source chemical(s)

Constituent types of the target substance and chemical structures of the source substances are shown in the data matrix, including physico-chemical properties and biodegradability information, thought relevant for read across.

Purity / Impurities

Constituent types of the target substanceare covered by the presented constituent types, there are no other constituent that impacts the biodegradability potential.

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 the Terpene hydrocarbon alcohols its key constituent Terpineol (in the form of Terpineol multi) is selected as analogue for the other constituents and for this substance biodegradation information is available.

Structural similarities and differences: TheTerpene hydrocarbon alcohols consist at least of 40% Terpineol and therefore have the same structure. All and other constituents have similar backbones, mostly containing a hydrocarbon cyclohexyl/hexene group with a (branched) alkyl chain, and/or alkyl bridge over the cyclohexyl ring.

Bioavailability:Terpene hydrocarbon alcohols constituents are all bioavailable based on molecular weight and log Kow.

Biodegradable fragments: The Terpene hydrocarbon alcohols have similar backbones and therefore have similar biodegradable fractions.

Information on other constituents: Terpinolene (Solely hydrocarbon type Cas no 586-62-9 and EC No. 209-578-0) and Camphor (Ketone type Cas no. 76-22-2; EC no. 200-945-0) are ready biodegradable based on information from the ECHA website.

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

Data matrix

The relevant information on physico-chemical properties and toxicological characteristics are presented in the Data Matrix.

Conclusions on biodegradability for hazard and risk assessment

For the Terpene hydrocarbon alcohols no biodegradation information is available. Read-across is used to fill this data gap. 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. This documentation is presented in the current text. For the key constituentTerpineol multi and analogue for other constituents, data is available from a reliable study according to OECD TG 310 in which the substance was found to be readily biodegradable. This information can be used for read across.

Final conclusion:The Terpene hydrocarbon alcohols arereadily biodegradable.

Data matrix supporting the ready biodegradability information relevant for read across to the Terpene hydrocarbon alcohols from Terpineol multi

Terpene hydrocarbon alcohols

Terpineol hydrocarbon alcohols

Terpineol multi

 

Target

Source

Structure

Not applicable

(α-Terpineol and γ-Terpineol)

CAS

Not applicable

98-55-5 and 8000-41-7

EC No.

945-149-0

202-680-6 /232-268-1

Reach registration

2018

Registered

Molecular weight

136-154

154

Phys-chem properties

 

 

Appearance

Liquid

Liquid

Log Kow

4.9 (3.3-5.5; IFF)

2.6

Identity, Constituent type (%)

100%

 

Solely hydrocarbons

 

 

Terpinolene type

0-15

 

Alcohol type

 

>80

Tertiary alcohols (e.g. Terpineol)

40-90

 

Secondary alcohols (e.g. Borneol)

7-40

 

Ketone type

-

 

Camphor-Type

0-17%

 

Ether type

 

 

Aromatic ether type

<4%

 

Environmental fate

 

 

Biodegradation 

Readily biodegradable

(Read across)

Readily biodegradable

(OECD TG 310)