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Environmental fate & pathways

Biodegradation in water and sediment: simulation tests

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Endpoint:
biodegradation in water: sediment simulation testing
Type of information:
read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
weight of evidence
Justification for type of information:
1. HYPOTHESIS FOR THE CATEGORY APPROACH
The hypothesis is that the category members have similar structures and properties (very rapid biodegradability), which are consistent across the category (Scenario 6 in the RAAF). The consistency of this property across the category is discussed in the endpoint summary.

2. SOURCE AND TARGET CHEMICAL(S) (INCLUDING INFORMATION ON PURITY AND IMPURITIES)
Please refer to the test material identity information within each endpoint study record and in the endpoint summary. The source chemicals and the target chemical are linear aliphatic alcohols which are members of the long chain linear aliphatic alcohol Category.

The long chain linear aliphatic alcohol Category has at its centre an homologous series of increasing carbon chain length alcohols. The category members are structurally very similar. They are all primary aliphatic alcohols with no other functional groups. The category members are linear or contain a single short-chain side-branch at the 2-position in the alkyl chain, which does not significantly affect the properties (‘essentially linear’). The category members have saturated alkyl chains or contain a small proportion of naturally-occurring unsaturation(s) which does not significantly affect the properties. The branched and unsaturated structures are considered to have such similar properties that their inclusion in the category is well justified.
Impurities: Linear and/or ‘essentially linear’ long chain aliphatic alcohols of other chain lengths may be present. These are not expected to contribute significantly to the properties in respect of this endpoint due to consistent properties (see point 3).
There are no impurities present at or above 1% which are not category members or which would affect the properties of the substance.

3. CATEGORY JUSTIFICATION
The category members are structurally very similar (see point 2) and are biochemically very similar. The metabolic synthesis and degradation pathways are well established. This Category is associated with a consistency and predictability in the physicochemical, environmental, and toxicological property data across its members.

The consistency of observations in this property across the range of chain lengths covered by this Category is described in the Endpoint Summary and in the Category Report attached in Section 13.

In this registration, the information requirement is based on read-across from members of the category with shorter chain length and similar chemical properties, for which there would be an expectation of consistency in behaviour.

4. DATA MATRIX
A data matrix for the C6-24 alcohols Category is attached in Section 13.
Reason / purpose:
read-across source
Reason / purpose:
read-across source
Reason / purpose:
read-across source
Qualifier:
equivalent or similar to
Guideline:
other: other guideline: OECD 314D. Deviations, reliability, and validity evaluated against current OECD 314D (Oct. 3, 2008)
Deviations:
no
GLP compliance:
no
Remarks:
study conducted before 2008
Oxygen conditions:
aerobic
Inoculum or test system:
natural sediment
Details on inoculum:
The "inoculum" was what was naturally present in the sediment sample collected from the river.
Duration of test (contact time):
> 60 - < 149 d
Compartment:
other: sediment, material (mass) balance
% Recovery:
80.4
St. dev.:
13.5
% Degr.:
76.5
Parameter:
CO2 evolution
Sampling time:
92 d
Remarks on result:
other: Normalized to 100% mass balance
% Degr.:
96.4
Parameter:
other: Total removal (mineralized + metabolite + incorporated into solids)
Sampling time:
92 d
Remarks on result:
other: Normalized to 100% mass balance
% Degr.:
61.1
Parameter:
CO2 evolution
Sampling time:
60 d
Remarks on result:
other: Normalised to 100% mass balance
% Degr.:
88.4
Parameter:
other: Total removal (miineralized + metabolised + incorporated)
Sampling time:
60 d
Remarks on result:
other: Normalized to 100% mass balance
% Degr.:
83.6
Parameter:
CO2 evolution
Sampling time:
149 d
Remarks on result:
other: Normalized to 100% mass balance
% Degr.:
ca. 100
Parameter:
other: Total removal (mineralised + metabolised + incorporated)
Sampling time:
149 d
Remarks on result:
other: Normalized to 100% mass balance
Compartment:
sediment
DT50:
>= 0.04 - <= 1.1 d
Type:
other: Two Compartment First Order Model
Remarks on result:
other: Half life for primary degradation of readily bioavailable test material (compartment 1)
Compartment:
sediment
DT50:
>= 11.4 - <= 34.7 d
Type:
other: Two Compartment First Order Model
Remarks on result:
other: Half life for primary degradation of less bioavailable test material (compartment 2)
Compartment:
sediment
DT50:
>= 0.15 - <= 1.7 d
Type:
other: Two Compartment First Order Mode
Remarks on result:
other: Half-life for mineralization of readily bioavailable test material (compartment 1)
Compartment:
sediment
DT50:
>= 13.9 - <= 34.9 d
Type:
other: Two Compartment First Order Model
Remarks on result:
other: Half-life for mineralization of less bioavailable test material (compartment 2)
Other kinetic parameters:
other: Two compartment first order decay model (provided the best statistical fit) 8.9 ± 1.8 d-1 for primary degradation of readily bioavailable test materia... (see attached file)
Transformation products:
yes
No.:
#1
Details on transformation products:
Please refer to 'Transformation products' under 'Details on results' section.
Evaporation of parent compound:
no
Volatile metabolites:
no
Residues:
yes
Details on results:
TEST CONDITIONS
- Aerobicity, moisture, temperature and other experimental conditions maintained throughout the study: Yes

TRANSFORMATION PRODUCTS:
Fatty acid represented approximately 6% of the radioactivity during the first 2 d and then decreased in abundance to <2% after Day 92. A total of 3
metabolites were identified by TLC:
Rf (TLC) Substance
<0.00 Polar metabolite
0.05 Polar metabolite
0.23 Parent
0.66 Long-chain fatty acid


EXTRACTABLE RESIDUES:
All of the abiotic extracts contained a major peak (Rf 0.23) associated with parent and two minor polar peaks that had Rf values of <0.0 and 0.05 that remained relatively constant with time. This finding indicated that the Tetradecanol degraded slightly before the test initiation but had remained biologically inactive through the experiment. The average recovery of parent from the abiotic samples was 58.1%. Biotic samples revealed the presence of same three peaks as observed in abiotic treatment, as well as a peak corresponding to long chain fatty acid. However, these polar metabolites in the biotic treatment decreased with time. In the biotic treatments, primary degradation of the parent started immediately with metabolites accounting for 18.7% of the radioactivity in the 15 min sample (normalized to 100% mass balance). After 1 d, only 24.7% of the dosed radioactivity was recovered as parent (normalized to 100% mass balance).

- % of applied amount at Day 0: 81.2%% in active flask (parent or metabolite; sample time was 0.01 d; normalized to 100% mass balance).

- % of applied amount at end of study period: 6.6% in active flask (parent or metabolite; sample time was 92 d; normalized to 100% mass balance).

NON-EXTRACTABLE RESIDUES:
The fraction associated with the extracted solids initially increased over time reaching a maximum level of 25.9% at day 2 (32.9%, normalized for 100% mass balance), and decreased to 14.2% by Day 92 (17.0%, normalized for 100% mass balance) in biotic treatment. In the abiotic treatments, the
percent of radioactivity associated with the extracted solids ranged from 2.4 to 7.2%.

- % of applied amount at Day 0: 4.0% in active flask (Solids; sample time was 0.01 d; normalized to 100% mass balance).

- % of applied amount at end of study period: 17.0% in active flask (Solids; sample time was 92 d; normalized to 100% mass balance).

MINERALISATION:
Production of 14CO2 increased throughout the study and accounted for 76.5% of the initial radioactivity dosed on Day 92 (normalized for 100% mass balance). For details, please refer to ‘Table 1’ in the ‘Any other information on results incl. tables’ section.

VOLATILIZATION:
No volatilization of test material was observed as the TLC analysis of the abiotic control revealed that the parent test material remained intact.

NOTE: the test was conducted for 188 d, and the results at 188 d are presented in the Tables below. However, the results reported in this robust summary are at 92 d, because the % of radioactivity as parent, as metabolites, and as long chain fatty acid was quantified at Day 92. At Day 188, these endpoints were not analyzed because of the low level of radioactivity in the extract.
Results with reference substance:
Not applicable

Table 1: Percent of Dosed Radioactivity recovered as Parent, Metabolites, associated with Extracted Solids and mineralised to CO2 in the Biotic samples.

Time (days)

Parent (Rf 0.23)

Polar metabolite (Rf <0.00)

Polar metabolite (Rf 0.05)

Long Chain Fatty Acid (Rf 0.66)

Solids

CO2

Total Recovery/Mass balance

0.01

75.0 ± 5.1

4.0 ± 0.2

10.5 ± 2.0

7.9 ± 0.2

4.8 ± 0.1

17.8 ± 2.4

120.1 ± 1.4

0.25

21.8 ± 1.3

2.2 ± 0.7

3.3 ± 0.9

5.1 ± 0.9

22.7 ± 0.8

25.6 ± 2.2

80.8 ± 1.4

0.5

18.9 ± 5.0

1.3 ± 0.2

1.8 ± 0.1

5.9 ± 1.2

25.2 ± 1.5

24.0 ± 1.5

77.0 ± 6.1

1

20.2 ± 0.9

1.0 ± 0.2

2.2 ± 0.3

6.8 ± 0.9

25.0 ± 0.2

26.6 ± 0.4

81.7 ± 1.7

2

15.7 ± 0.3

1.3 ± 0.5

1.9 ± 0.2

6.4 ± 0.3

25.9 ± 1.4

27.5 ± 0.1

78.8 ± 2.2

3

14.9 ± 1.8

1.0 ± 0.1

2.1 ± 0.0

4.8 ± 0.8

25.6 ± 1.4

28.7 ± 1.0

77.2 ± 2.1

7

9.2 ± 0.7

0.8 ± 0.0

1.9 ± 0.5

3.8 ± 1.0

22.2 ± 0.7

33.7 ± 0.2

71.7 ± 0.8

10

9.5 ± 0.8

1.0 ± 0.3

1.8 ± 0.1

3.1 ± 0.1

20.2 ± 0.5

35.5 ± 0.9

71.2 ± 2.6

15

8.7 ± 2.8

1.3 ± 0.8

1.6 ± 0.6

2.8 ± 0.2

18.7 ± 1.0

36.7 ± 0.4

69.8 ± 3.7

36

8.1 ± 2.0

1.0 ± 0.3

1.5 ± 1.0

2.4 ± 0.1

17.3 ± 0.3

39.6 ± 0.2

69.9 ± 0.4

92

3.1 ± 0.0

0.4 ± 0.4

0.4 ± 0.5

1.6 ± 0.5

14.2 ± 0.4

63.9 ± 1.7

83.5 ± 1.8

188

NA

NA

NA

NA

13.3 ± 0.6

67.3 ± 0.4

83.2 ± 1.9

NA = Not Analysed due to low level of radioactivity in extract

Mean   = 80.4 ± 13.5

Sediment collected from Ohio River (test conducted under aerobic conditions).

Table 2: Percent of Dosed Radioactivity recovered as Parent, Metabolites, and associated with Extracted Solids in the Abiotic samples.

Time (days)

Parent (Rf 0.23)

Polar metabolite (Rf <0.03)

Polar metabolite (Rf 0.03)

Long Chain Fatty Acid (Rf 0.66)

Solids

Total Recovery/Mass balance

0.01

72.6 ± 8.1

3.3 ± 1.2

6.9 ± 1.1

ND

2.4 ± 0.1

85.2 ± 10.5

1

76.8 ± NC

2.7 ± NC

7.0 ± NC

ND

2.4 ± 0.1

86.2 ± 3.5

2

67.3 ± 5.2

2.9 ± 0.3

7.9 ± 0.6

ND

3.5 ± 0.3

81.5 ± 4.7

3

72.5 ± 1.8

2.6 ± 0.4

6.8 ± 0.5

ND

3.7 ± 0.1

85.6 ± 2.6

7

73.2 ± 6.7

1.8 ± 0.5

4.2 ± 0.7

ND

3.9 ± 0.3

83.0 ± 6.1

10

79.2 ± 1.2

1.4 ± 0.0

4.6 ± 0.5

ND

3.9 ± 0.3

83.0 6± 6.1

15

77.7 ± 0.4

0.9 ± 0.1

2.6 ± 0.6

ND

4.0 ± 0.1

85.3 ± 0.3

188

58.1 ± 13.0

3.1 ± 0.9

6.8 ± 6.0

ND

7.2 ± 0.4

78.3 ± 2.7

ND = Not Detected            NC = Not Calculated

Mean = 84.3 ± 3.3

Table 3: kinetic parameters describing the primary degradation and mineralisation of the test substance in biotic sediment using a two compartment first order model

Sample

Pool A (%)

1 ­(hrs­-1)

Half-life Pool A (days)

Pool B(%)

2 ­(hrs­-1)

Half-life Pool B (days)

Primary degradation

68.4

8.9

0.04

18.7

0.03

11.4

Mineralisation

26.0

4.7

0.15

42.2

0.02

34.9

Validity criteria fulfilled:
yes
Conclusions:
Three studies covering two alcohol chain lengths and two different natural freshwater sediments determined the substances to be extensively degrade or mineralised with very rapid transformation rates for the more readily bioavailable portion of the substance. A similar result would be expected for the Target alcohol substance.
Endpoint:
biodegradation in water: simulation testing on ultimate degradation in surface water
Type of information:
read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
key study
Justification for type of information:
1. HYPOTHESIS FOR THE CATEGORY APPROACH
The hypothesis is that the category members have similar structures and properties (very rapid biodegradability), which are consistent across the category (Scenario 6 in the RAAF). The consistency of this property across the category is discussed in the endpoint summary.

2. SOURCE AND TARGET CHEMICAL(S) (INCLUDING INFORMATION ON PURITY AND IMPURITIES)
Please refer to the test material identity information within each endpoint study record and in the endpoint summary. The source chemicals and the target chemical are linear aliphatic alcohols which are members of the long chain linear aliphatic alcohol Category.

The long chain linear aliphatic alcohol Category has at its centre an homologous series of increasing carbon chain length alcohols. The category members are structurally very similar. They are all primary aliphatic alcohols with no other functional groups. The category members are linear or contain a single short-chain side-branch at the 2-position in the alkyl chain, which does not significantly affect the properties (‘essentially linear’). The category members have saturated alkyl chains or contain a small proportion of naturally-occurring unsaturation(s) which does not significantly affect the properties. The branched and unsaturated structures are considered to have such similar properties that their inclusion in the category is well justified.
Impurities: Linear and/or ‘essentially linear’ long chain aliphatic alcohols of other chain lengths may be present. These are not expected to contribute significantly to the properties in respect of this endpoint due to consistent properties (see point 3).
There are no impurities present at or above 1% which are not category members or which would affect the properties of the substance.

3. CATEGORY JUSTIFICATION
The category members are structurally very similar (see point 2) and are biochemically very similar. The metabolic synthesis and degradation pathways are well established. This Category is associated with a consistency and predictability in the physicochemical, environmental, and toxicological property data across its members.

The consistency of observations in this property across the range of chain lengths covered by this Category is described in the Endpoint Summary and in the Category Report attached in Section 13.

In this registration, the information requirement is based on read-across from hexadecan-1-ol, a member of the category with shorter chain length and similar chemical properties, for which there would be an expectation of consistency in behaviour.

4. DATA MATRIX
A data matrix for the C6-24 alcohols Category is attached in Section 13.
Reason / purpose:
read-across source
Qualifier:
equivalent or similar to
Guideline:
other: OECD 314D. Deviations, reliability, and validity evaluated against current OECD 314D (Oct. 3, 2008)
Deviations:
no
Principles of method if other than guideline:
Radiolabelled test material was dosed to freshly collected river water and inoculum. Samples collected periodically were assayed for 14C activity by Liquid Scintillation Counting (LSC).


Radiolabelling:
yes
Oxygen conditions:
aerobic
Inoculum or test system:
other: River water supplemented with domestic activated sludge
Details on inoculum:
- Source of inoculum/activated sludge: Activated sludge collected from the Downingtown Regional Water Pollution Control Center, Downingtown, Pennsylvania

- Storage length and conditions: The sludge was held overnight with aeration

- Storage length: Overnight

- Preparation of inoculum for exposure: The sludge was screened to remove large clumps and a TSS level was determined. Based on this reading the sludge was added to two semi-continuous activated sludge units (SCAS) at a target solids level of 2,500 mg/L. The sludge was diluted to this concentration with tap water. Approx. 300 mL of mixed liquor was collected from each of the duplicate SCAS units, composited and homogenized at medium speed in a blender for 2 min. The homogenized sample was poured into a beaker and allowed to settle for 30 min. The supernatant was decanted and added to the flasks at a concentration of 0.1% v/v.

- Concentration of sludge: The sludge was adjusted to a target total suspended solids level of 2500 mg/L
Duration of test (contact time):
31 d
Initial conc.:
100 µg/L
Parameter followed for biodegradation estimation:
CO2 evolution
Details on study design:
TEST CONDITIONS
- Volume of test solution/treatment: Approx. 1L

- Composition of medium: Each 2 L test flask contained:1 L river water; 1 mL activated sludge; 241 µL dosing solution; - Test temperature: 20.6 - 22.5 °C

- pH: Not reported

- Aeration of dilution water: The flasks were placed on a rotary platform shaker and aerated continuously with a CO2 free air source.

- Suspended solids concentration: 2500 mg/L

- Continuous darkness: Not reported

TEST SYSTEM
- Culturing apparatus: 2 L Erlenmeyer glass flasks

- Number of culture flasks/concentration: Two per concentration

- Method used to create aerobic conditions: The flasks were placed on a rotary platform shaker (100 to 150 rpm) and aerated continuously with a CO2 free air source. Air was purged through the scrubbing train at a constant rate which is adequate to provide 1-2 bubbles/second in the alkali traps. The CO2 scrubbing apparatus consisted of: (a) One empty 1 L plastic bottle, to prevent backflow; (b) Five 1 L plastic bottles containing 700 mL 10 N NaOH and (c) One empty 1 L plastic bottle to prevent overflow of alkali into the test containers connected in series with Tygon tubing to a pressurized air source (approx. 10-15 psi).

- Test performed in closed vessels: Yes

- Details of trap for CO2 and volatile organics if used: Glass bottles approx. 4 oz size containing 100 mL of 1.5 N KOH.

- Other: The study was terminated on Day 31 by adding 1 mL concentrated HCl to the flasks. Following an incubation of 3 d, duplicate 10 mL water samples were withdrawn from each flask and counted in Triton-X cocktail. Duplicate 1 mL samples from all three alkali traps were collected and counted in 20 mL Cab-O-Sil cocktail.

SAMPLING
- Sampling frequency: On Days 1, 3, 5, 7, 10, 14, 21, 28 and 31

- Sampling method: The first 14CO2 alkali trap in the individual trains was removed and a 1mL aliquot was counted in 20 mL of Cab-O-Sil. The remaining traps were moved one slot closer to the test flask and a new trap was added to the third slot. At the same time 10 mL water samples are withdrawn by syringe from each test flask and filtered through 0.2 µm filters. The filters were washed with 5 mL IPA/water, air dried, and counted in 20 mL of 3A cocktail to quantitate radioactivity in the biomass. The filtrate was treated as described in "Details on analytical methods" above.

- Sample storage before analysis: Not specified

CONTROL AND BLANK SYSTEM
- Inoculum blank: No

- Abiotic sterile control: No

- Toxicity control: No

STATISTICAL METHODS: Percent 14CO2 production vs time was analysed by the following empirical model: 14CO2 = a (1 - e(-k(t-c)))where,a = Extent of 14CO2 production (%)k = First order rate constant (day-1)t = Time of incubation (days)c = Lag period, if any (days). The constants a and k along with 95 % confidence intervals were generated for each treatment
Compartment:
other: water, material (mass) balance
% Recovery:
100
Remarks on result:
other: reported as 105% in source.
% Degr.:
ca. 92.4 - ca. 97.5
Parameter:
CO2 evolution
Sampling time:
31 d
Remarks on result:
other: based on range of results in two replicates
Other kinetic parameters:
first order rate constant
Transformation products:
not measured
Evaporation of parent compound:
not measured
Volatile metabolites:
not measured
Residues:
yes
Details on results:
TEST CONDITIONS
- Aerobicity , moisture, temperature and other experimental conditions maintained throughout the study: Yes

MAJOR TRANSFORMATION PRODUCTS: Not determined in the study.

MINOR TRANSFORMATION PRODUCTS: Not determined in the study.

MINERALISATION
- % of applied radioactivity present as CO2 at end of study: 97.5 and 92.4% for Flask 1 and 2 respectively. For details see ‘Table1’ and 'Table 2' below in the ‘Any other information on results incl. tables’ section.
Results with reference substance:
Not applicable

14 CO2 production of Cetyl Alcohol in river water (Study # 35425)

Day

Indirect % T 14CO2

Direct % T 14CO2

Biomass % 14C

Solution % 14C

Mass balance

1

66

47

23.9

10.1

81

3

68.7

56.4

20.2

11.1

87.7

5

68

65.3

22.7

9.3

97.3

7

73.9

73.8

19.1

7

99.9

10

74.7

80.4

19

6.3

105.7

14

80.5

80.9

13.3

6.2

100.4

21

85.8

93

9.8

4.5

107.3

28

89.9

96

7

3.1

106.1

31

91.7

97.5

6

2.2

105.7

 

 

Table 2: Flask 2

Day

Indirect % T 14CO2

Direct % T 14CO2

Biomass % 14C

Solution % 14C

Mass balance

1

60.2

40.8

28.9

10.9

80.6

3

69.6

53.9

19.9

10.5

84.3

5

66.2

63.4

23.4

10.4

97.2

7

71.8

69.9

18.5

9.7

98.1

10

73.1

78.8

19

7.8

105.6

14

81.8

81.2

11

7.2

99.4

21

87.9

86.1

7.3

4.8

98.2

28

91.6

91.5

5.4

3

99.9

31

93.6

92.4

4.3

2.1

98.8

Validity criteria fulfilled:
yes
Conclusions:
A reliable study conducted according to generally accepted scientific principles determined the substance to achieved a percentage degradation of 95.0% (CO2 produced) over 31 days, and rate constant for mineralization in surface water was 0.34 day-1. Results are the average of 2 test flasks. A similar result would be expected for the Target alcohol substance.
Endpoint:
biodegradation in water: sewage treatment simulation testing
Type of information:
read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
weight of evidence
Justification for type of information:
1. HYPOTHESIS FOR THE CATEGORY APPROACH
The hypothesis is that the category members have similar structures and properties (very rapid biodegradability), which are consistent across the category (Scenario 6 in the RAAF). The consistency of this property across the category is discussed in the endpoint summary.

2. SOURCE AND TARGET CHEMICAL(S) (INCLUDING INFORMATION ON PURITY AND IMPURITIES)
Please refer to the test material identity information within each endpoint study record and in the endpoint summary. The source chemicals and the target chemical are linear aliphatic alcohols which are members of the long chain linear aliphatic alcohol Category.

The long chain linear aliphatic alcohol Category has at its centre an homologous series of increasing carbon chain length alcohols. The category members are structurally very similar. They are all primary aliphatic alcohols with no other functional groups. The category members are linear or contain a single short-chain side-branch at the 2-position in the alkyl chain, which does not significantly affect the properties (‘essentially linear’). The category members have saturated alkyl chains or contain a small proportion of naturally-occurring unsaturation(s) which does not significantly affect the properties. The branched and unsaturated structures are considered to have such similar properties that their inclusion in the category is well justified.
Impurities: Linear and/or ‘essentially linear’ long chain aliphatic alcohols of other chain lengths may be present. These are not expected to contribute significantly to the properties in respect of this endpoint due to consistent properties (see point 3).
There are no impurities present at or above 1% which are not category members or which would affect the properties of the substance.

3. CATEGORY JUSTIFICATION
The category members are structurally very similar (see point 2) and are biochemically very similar. The metabolic synthesis and degradation pathways are well established. This Category is associated with a consistency and predictability in the physicochemical, environmental, and toxicological property data across its members.

The consistency of observations in this property across the range of chain lengths covered by this Category is described in the Endpoint Summary and in the Category Report attached in Section 13.

In this registration, the information requirement is based on read-across from octadecan-1-ol, a member of the category with shorter chain length and similar chemical properties, for which there would be an expectation of consistency in behaviour.

4. DATA MATRIX
A data matrix for the C6-24 alcohols Category is attached in Section 13.
Reason / purpose:
read-across source
Reason / purpose:
read-across source
Reason / purpose:
read-across source
Inoculum or test system:
activated sludge, domestic, non-adapted
Duration of test (contact time):
30 d
% Degr.:
ca. 66
Parameter:
CO2 evolution
Remarks:
(mineralization)
Sampling time:
48 h
Remarks on result:
other: Measured with C16
% Degr.:
ca. 99.1
Parameter:
DOC removal
Sampling time:
30 d
Remarks on result:
other: Comparable to OECD 303
Remarks:
C18
% Degr.:
ca. 93 - ca. 99.9
Parameter:
other: BOD
Remarks on result:
other: equivalent or similar to OECD 314B
Remarks:
C18
Transformation products:
not measured

Description of key information

Key value for chemical safety assessment

Half-life in freshwater:
2.1 d
at the temperature of:
12 °C
Half-life in freshwater sediment:
6 d
at the temperature of:
12 °C

Additional information

In accordance with Column 2 of REACH Annex IX, the simulation test on ultimate degradation in surface water and the sediment simulation test (required in Sections 9.2.1.2 and 9.2.1.4 respectively of the REACH regulation) do not need to be conducted as the substance is readily biodegradable. Identification of degradation products (required in Section 9.2.3 of the REACH regulation) is also not necessary because extensive mineralisation has been demonstrated. Measured degradation in sediment data are available for two analogous saturated alcohols (described below). In view of the similar adsorption coefficient and water solubility of docosan-1-ol compared to these linear alcohols, for which simulation tests are available, it can be expected that biodegradation of docosan-1-ol in similar substrates will be equivalent.

It is notable that significant technical difficulties were encountered during method development for a recent study of adsorption/desorption (OECD 106, Wildlife, 2015), with the structurally analogous substance decan-1-ol (CAS 112-30-1), using natural standard soils, in that it was not possible to detect sufficient substance and establish equilibrium in non-sterilised soil samples. Refer to the Discussion under Section 5.2.3 for a full description of the relevant findings. Half-lives in non-sterilised test soils were in the range approximately 15 minutes to 2 hours. The polar degradation product is most likely the corresponding carboxylic acid, though it was not definitively identified. The chromatograms show that decan-1-ol was effectively fully removed in all four soil types by the 24 h time point (in the case of 2 of the soil types, within 2 hours). Though sediments were not studied in this test, similar instability is to be expected and similar findings would be anticipated for docosan-1-ol.

Discussion of trends in the Category of C6 -24 linear and essentially-linear aliphatic alcohols

Sediment simulation testing

The degradation of C14 linear alcohol in sediments was determined in two studies conducted in accordance with OECD 314 test method and using radiolabelled (14C) test substance. After 92 days, 76.5% mineralisation to CO2 was obtained using sediment from Ohio River near Cincinnati, Ohio area (Federle T W and Itrich N R, 2010a). After 149 days, 83.6% mineralisation to CO2 was obtained using Lytle Creek sediments from Wilmington, Ohio (Federle T W and Itrich N R, 2010b).

The degradation of C18 linear alcohol in sediments was determined in a similar study, conducted in accordance with OECD 314 test method and using radiolabelled (14C) test substance (Itrich, 2010). After 60 days, 61.1% mineralisation to CO2was obtained using sediment from Ohio River, and 71.6% mineralisation to CO2 after 60 days was obtained using Great Miami River sediments.

The radiochemical analytical results for sediment-associated and aqueous alcohols in these three sediment degradation studies indicated that there are two pools of substance, understood to represent the strength of adsorption of the alcohol to sediment particles, which degrade at different rates.

In another study, using activated sludge and radiolabelled (14C) test substance, 76.7% mineralisation of C14 to CO2 after 48 h was determined in accordance with OECD 314B (Federle, 2005). In the same study, 66.3% mineralisation of C16 to CO2after 48h was determined. Another OECD 314 test using activated sludge and using radiolabelled (14C) test substance, indicates 95% mineralisation of C16 to CO2 in 31 days (Federle, 1993).

Activated sludge simulation testing

In another study, an activated sludge simulation test using similar methods to the sediment studies described above, was conducted with radiolabelled C12 alcohol.

 

A simulation of the biodegradation of Dodecanol in activated sludge was conducted under aerobic conditions in accordance with the OECD 314B guideline (Federle, 2005). A solution of radiolabeled Dodecanol (1-14C) was tested at 9.8 µg/L.  The inoculum was activated sludge obtained from Fairfield Wastewater Treatment Plant (Fairfield, OH), which receives predominantly domestic wastewater. The disappearance of parent and progression of metabolite formation and decay were monitored over time by thin layer chromatography with radioactivity detection. Production of CO2was determined by comparing total radioactivity in a bioactive treatment compared to that in an abiotic control using liquid scintillation counting (LSC).

 

After 48 h, 74% was mineralized, 20.7% was non-extractable (solids), 9.4% was metabolite, and 0.8% remained as parent. The rate constants for biodegradation of Dodecanol in activated sludge were:

Primary biodegradation: 113 h-1

Mineralization: 11 h-1

 

This biodegradation simulation test satisfied the guideline requirements for the OECD 314 B simulation tests to assess the biodegradability of chemicals discharged in wastewater.