(Z)-N-octadecyldocos-13-enamide

Biodegradation in water and sediment: simulation tests

Link to relevant study record(s)

Reference

Endpoint:

biodegradation in water: sediment simulation testing

Type of information:

experimental study

Adequacy of study:

key study

Study period:

07 May 2019 to 22 Apr 2020

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 308 (Aerobic and Anaerobic Transformation in Aquatic Sediment Systems)

Version / remarks:

2002

GLP compliance:

yes (incl. QA statement)

Radiolabelling:

yes

Oxygen conditions:

aerobic

Inoculum or test system:

natural water / sediment: freshwater

Details on source and properties of surface water:

- Location : Calwich Abbey Lake UK, Emperor Lake UK
- Storage conditions: 5 ± 3°C
- pH at time of collection: 8.40 in Calwich Abbey Lake UK, 6.83 Emperor Lake UK
- Oxygen concentration (% saturation) initial/final: 95.6/87.7 & 96.9/89.7
- Hardness (CaCO3): Calwich Abbey Lake 260 mg/L & Emperor Lake 46.4 mg/L
- Dissolved organic carbon (%): Calwich Abbey Lake 4.89 & Emperor Lake 1.91
- Water filtered: yes
- Type and size of filter used, if any: Prior to use the sediment was passed through a 2 mm sieve and the water was passed through a 0.2 mm sieve.

Details on source and properties of sediment:

- Location : Calwich Abbey Lake UK, Emperor Lake UK
- Storage conditions: 5 ± 3°C
- Textural classification (i.e. %sand/silt/clay): Silt Loam for Calwich Abbey Lake & Sandy clay loam for Emperor Lake
- pH at time of collection: 7.7 (CAL) and 5.8 (EL)
- Organic carbon (%): 4.89 and 1.91 for CAL and EL respectively
- CEC (meq/100 g): 15.4 and 15.4 for CAL and EL respectively
- Bulk density (g/cm³): not determined
- Sediment samples sieved: yes

Duration of test (contact time):

99 d

Initial conc.:

0.04 mg/L

Based on:

test mat.

Parameter followed for biodegradation estimation:

radiochem. meas.

Details on study design:

TEST CONDITIONS
- Composition of medium:
Calwich Abbey Lake Emperor Lake
Total organic carbon (mg/L) 5.43 8.46
Total nitrogen (mg/L) 3.33 1.01
Total phosphorus (mg/L) 0.02 0.02
Total suspended solids (mg/L) 8.5 46.0
Hardness as CaCO3 (mg/L) 260 46.4

- Test temperature: 12 °C
- pH: pH in water 7.7 (CAL); 5.8 (EL)
- pH adjusted: no
- CEC (meq/100 g): 15.4 (meq/100 g) for both
- Aeration of dilution water: yes
- Suspended solids concentration: Total suspended solids (mg/L) 8.5 for CAL & 46.0 for EL
- Continuous darkness: yes
- Any indication of the test material adsorbing to the walls of the test apparatus: no
- Test performed in closed vessels due to significant volatility of test substance: yes
- Test performed in open system: no
- Details of trap for CO2 and volatile organics if used: 4. Vessel containing 1 M aqueous potassium hydroxide solution with phenolphthalein indicator (to trap 14CO2)

SAMPLING
- Sampling frequency: Duplicate samples of each aquatic sediment were taken for analysis immediately after test item application and after 1, 7, 14, 28, 60 and 99 days of incubation.
- Sampling method used per analysis type: Trapping media were taken for analysis with the associated samples at sampling. In addition, trapping media associated with all remaining vessels were taken for analysis and replaced with fresh media at 14, 28, 42, 60, 77, 88 and 99 days after application.
- Sample storage before analysis: Aqueous samples and sediment extracts were stored at 5 ± 3°C prior to analysis.

DESCRIPTION OF CONTROL AND/OR BLANK TREATMENT PREPARATION
CONTROL AND BLANK SYSTEM
- same as test item

Compartment:

natural water / sediment: freshwater

% Total extractable:

71

% Non extractable:

6.4

% CO2:

13.6

% Other volatiles:

0

% Recovery:

93.3

Remarks on result:

other: 99 d - Emperor Lake

Compartment:

natural water / sediment: freshwater

% Total extractable:

28.2

% Non extractable:

0

% CO2:

0

% Other volatiles:

0

% Recovery:

79.9

Remarks on result:

other: 0 d - Emperor Lake

Compartment:

natural water / sediment: freshwater

% Total extractable:

73.7

% Non extractable:

3.5

% CO2:

12.8

% Other volatiles:

0

% Recovery:

90.1

Remarks on result:

other: 99 d - Calwich Abbey Lake

Compartment:

natural water / sediment: freshwater

% Total extractable:

14.7

% Non extractable:

0

% CO2:

0

% Other volatiles:

0

% Recovery:

75.8

Remarks on result:

other: 0 d - Calwich Abbey Lake

Compartment:

natural water / sediment: freshwater

DT50:

6 630 d

Type:

not specified

Temp.:

12 °C

Remarks on result:

other: Emperor Lake

Compartment:

natural water / sediment: freshwater

DT50:

5 020 d

Type:

not specified

Temp.:

12 °C

Remarks on result:

other: Calwich Abbey Lake

Transformation products:

no

Remarks:

Test item was degraded to two low level unidentified degradates (≤0.5% applied radioactivity), incorporated into bound (non-extractable) radioactivity and mineralized to carbon dioxide.

Details on transformation products:

Test item was degraded to two low level unidentified degradates (≤0.5% applied radioactivity), incorporated into bound (non-extractable) radioactivity and mineralized to carbon dioxide.

Evaporation of parent compound:

no

Volatile metabolites:

no

Details on results:

TEST CONDITIONS
- Aerobicity, moisture, temperature and other experimental conditions maintained throughout the study: Yes
- Anomalies or problems encountered (if yes): The temperature of the incubation room during the acclimatization phase of the preliminary experiment deviated from the acceptable range of 12 ± 2ºC on several occasions. This deviation occurred between the 10 May 2019 to 14 May 2019 (5 days). The maximum temperature reached was 14.9°C and the maximum duration of temperature excursion from the acceptable range was approximately 10 hours 16 minutes.
This deviation was not considered to have affected the outcome of the study.


MAJOR TRANSFORMATION PRODUCTS
- none

MINOR TRANSFORMATION PRODUCTS
Test item was degraded to two low level unidentified degradates (≤0.5% applied radioactivity), incorporated into bound (non-extractable) radioactivity and mineralized to carbon dioxide.

Microbiological Characterization of the Aquatic Sediments

Start of incubation

 

	Calwich Abbey Lake		Emperor Lake
	Sediment	Water	Sediment	Water
Aerobic bacteria	4.75×10^6	5.61×10^6	8.30×10^6	1.05×10^7
Aerobic bacterial spores	2.65×10^5	8.25×10^3	4.30×10^5	50
Anaerobic bacteria	4.15×10^4	nm	3.55×10^4	nm
Anaerobic bacterial spores	4.55×10^4	nm	3.45×10^3	nm
Actinomycetes	2.75×10^4	<10	3.10×10^4	<10
Fungi	1.70×10^3	5.90×10^2	5.20×10^4	7.90×10^2

 

End of incubation (untreated)

 

	Calwich Abbey Lake		Emperor Lake
	Sediment	Water	Sediment	Water
Aerobic bacteria	5.00x10^5	75	8.95x10^5	50
Aerobic bacterial spores	4.00x10^4	20	7.30x10^4	<10
Anaerobic bacteria	6.65x10^4	nm	5.20x10^4	nm
Anaerobic bacterial spores	9.55x10^3	nm	3.15x10^4	nm
Actinomycetes	5.85x10^3	<10	2.40x10^4	<10
Fungi	2.00x10^3	<10	3.50x10^4	<10

 

End of incubation (solvent treated)

 

	Calwich Abbey Lake		Emperor Lake
	Sediment	Water	Sediment	Water
Aerobic bacteria	3.30x10^5	50	1.05x10^6	1.05x10^2
Aerobic bacterial spores	3.35x10^4	15	6.40x10^4	25
Anaerobic bacteria	7.10x10^4	nm	5.95x10^4	nm
Anaerobic bacterial spores	6.30x10^4	nm	5.75x10^4	nm
Actinomycetes	6.05x10^3	<10	3.75x10^3	<10
Fungi	1.75x10^3	<10	2.95x10^4	<10

Results are expressed as colony forming units/g

nm          not measured

 

 

 

 

Mean Distribution and Recovery of Radioactivity in Calwich Abbey Lake Aquatic Sediment

	Time after application (days)
	0	1	7	14	28	60	99
Water	61.1	85.7	31.2	14.6	6.0	1.9	nd
Partition of water:
Organic phase (Dichloromethane)	58.8^(a)	81.7^(a)	25.3^(a)	9.2^(a)	1.9^(a)	-	-
Aqueous phase	0.7^(a)	0.9^(a)	2.4^(a)	2.6^(a)	3.2^(a)	-	-
Sediment:
Extract 1a (Aqueous)	nd	nd	0.6	0.6	0.8	0.8	0.4
Extract 1 (Dichloromethane)	11.0	6.3	33.8	34.0	20.5	35.9	30.0
Extract 2 (Dichloromethane)	3.0	2.7	12.9	11.8	18.6	14.6	12.5
Extract 3 (Tetrahydrofuran)	0.7	-	8.6	14.7	25.0	13.2	13.3
Extract 4 (Tetrahydrofuran)	-	-	1.2	3.4	2.6	4.2	3.0
Extract 5 (Tetrahydrofuran)	-	-	-	2.9	7.5	2.4	11.4
Extract 6 (Tetrahydrofuran)	-	-	-	-	2.2	-	3.1
Vessel Rinse (Tetrahydrofuran)	<0.1	-	-	-	-	-	-
Total extractable	14.7	9.0	57.1	67.4	77.2	71.1	73.7
Non-extractable	nd	1.8	1.0	3.4	3.4	4.1	3.5
Total in sediment	14.7	10.8	58.1	70.8	80.6	75.2	77.2
Organic volatiles	-	nd	nd	0.1	nd	nd	0.1
CO2	-	0.2	2.3	3.0	6.2	11.3	12.8
Total recovery	75.8	96.7	91.6	88.5	92.8	88.4	90.1

Results are expressed as % applied radioactivity

-               not applicable

nd           not detected

^(a)            Values are calculated from mean portions of water removed for partitions

Total in sediment is calculated as means from total extractable + non-extractable; total recovery is calculated as water + total in sediment + organics (volatile) + CO_2.

Extractions 1 to 6 and vessel rinse performed at ambient temperature.  Solvent used indicated in brackets

 

 

 

Mean Distribution and Recovery of Radioactivity in Emperor Lake Aquatic Sediment

	Time after application (days)
	0	1	7	14	28	60	99
Water	51.7	80.2	46.4	32.6	21.8	5.3	2.3
Partition of water:
Organic phase (Dichloromethane)	47.9^(a)	73.4^(a)	43.5^(a)	27.5^(a)	18.4^(a)	4.2^(a)	-
Aqueous phase	0.8^(a)	2.1^(a)	2.3^(a)	2.9^(a)	2.5^(a)	1.1^(a)	-
Sediment:
Extract 1a (Aqueous)	nd	nd	0.6	0.5	3.0	2.0	1.4
Extract 1 (Dichloromethane)	23.0	10.7	20.7	18.6	4.4	30.2	13.1
Extract 2 (Dichloromethane)	3.8	3.4	7.1	5.0	3.1	8.4	5.9
Extract 3 (Tetrahydrofuran)	1.4	-	16.5	15.3	25.6	20.2	25.9
Extract 4 (Tetrahydrofuran)	-	-	3.0	6.8	8.8	9.0	14.6
Extract 5 (Tetrahydrofuran)	-	-	-	4.7	15.2	3.4	2.6
Extract 6 (Tetrahydrofuran)	-	-	-	5.8	5.6	-	-
Extract 7 (Tetrahydrofuran)	-	-	-	3.2	1.7	-	-
Vessel Rinse (Tetrahydrofuran)	<0.1	-	-	-	-	-	-
Total extractable	28.2	14.1	47.9	59.9	67.4	73.2	71.0
Non-extractable	nd	3.3	nd	2.5	2.0	4.4	6.4
Total in sediment	28.2	17.4	47.9	62.4	69.4	77.6	77.4
Organic volatiles	-	nd	nd	nd	nd	nd	nd
CO2	-	0.1	0.8	2.1	3.7	8.1	13.6
Total recovery	79.9	97.7	95.1	97.1	94.9	91.0	93.3

Results are expressed as % applied radioactivity

-               not applicable

nd           not detected

^(a)            Values are calculated from mean portions of water removed for partitions

Total in sediment is calculated as means from total extractable + non-extractable; total recovery is calculated as water + total in sediment + organics (volatile) + CO_2.

Extractions 1 to 7 and vessel rinse performed at ambient temperature.  Solvent used indicated in brackets

 

 

 

 

Mean Proportions of Radioactive Components in Calwich Abbey Lake Aquatic Sediment

Water Phase

 

	Time after application (days)
	0	1	7	14	28	60	99
Test item (Rt ~20.7 mins)	57.8	81.0	24.7	7.9	NA	NA	NA
Others (a)	1.1	0.7	0.7	0.4	NA	NA	NA

 

Sediment Phase

 

	Time after application (days)
	0	1	7	14	28	60	99
Test item (Rt ~20.7 mins)	13.9	6.2	54.9	58.7	70.9	66.5	66.4
Others (a)	0.1	0.2	0.4	1.8	0.6	1.4	0.8

 

Total System

 

	Time after application (days)
	0	1	7	14	28	60	99
Test item (Rt ~20.7 mins)	71.7	87.2	79.6	66.6	70.9	66.5	66.4
Others (a)	1.2	0.9	1.1	2.2	0.6	1.4	0.8

Results are expressed as % applied radioactivity

(a)           Radioactivity distributed throughout regions of the chromatogram other than those specified and which   did not contain any discrete radioactive components

Rt            HPLC retention time of component

NA          Not analyzed (insufficient radioactivity)

 

 

 

 

Mean Proportions of Radioactive Components in Emperor Lake Aquatic Sediment

Water Phase

 

	Time after application (days)
	0	1	7	14	28	60	99
Test item (Rt ~20.7 mins)	46.8	72.4	42.7	26.5	17.8	3.9	NA
Unknown 1 (Rt ~18.6 mins)	-	-	-	-	-	-	NA
Unknown 2 (Rt ~13.8 mins)	-	-	-	-	-	0.2	NA
Others (a)	1.1	1.1	0.9	1.0	0.6	0.3	NA

 

Sediment Phase

 

	Time after application (days)
	0	1	7	14	28	60	99
Test item (Rt ~20.7 mins)	25.9	12.9	43.3	49.2	57.2	63.9	63.8
Unknown 1 (Rt ~18.6 mins)	0.5	0.4	-	-	-	-	-
Unknown 2 (Rt ~13.8 mins)	-	-	-	-	-	-	-
Others (a)	0.4	0.2	0.9	1.2	2.3	3.8	3.1

 

Total System

 

	Time after application (days)
	0	1	7	14	28	60	99
Test item (Rt ~20.7 mins)	72.7	85.3	86.0	75.7	75.0	67.8	63.8
Unknown 1 (Rt ~18.6 mins)	0.5	0.4	-	-	-	-	-
Unknown 2 (Rt ~13.8 mins)	-	-	-	-	-	0.2	-
Others (a)	1.5	1.3	1.8	2.2	2.9	4.1	3.1

Results are expressed as % applied radioactivity

(a) Radioactivity distributed throughout regions of the chromatogram other than those specified and which did not contain any discrete radioactive components

-               Not apparent or below the limit of detection

Rt            HPLC retention time of component

NA          Not Analyzed (insufficient radioactivity)

 

 

 

 

Kinetic Data for the Decline of Test item in Aquatic Sediment Systems

Test item

Aquatic sediment	Compartment	Kinetic model	DT50 (days)	DT90 (days)
Calwich Abbey Lake	water	SFO	3.71	12.3
Emperor Lake	water	FOMC	4.29	60.7
Calwich Abbey Lake	sediment	SFO	759	2520
Emperor Lake	sediment	SFO	>10000	>10000
Calwich Abbey Lake	total system	FOMC	5020	>10000
Emperor Lake	total system	FOMC	6630	>10000

Kinetic models:    SFO = single first order

                                FOMC = first order multi compartment

 

 

 

 

 

Validity criteria:

- Recoveries should range from 90% to 110% for labelled chemicals and from 70% to 110% for non-labelled chemicals.

Observed value:

the sum of radioactivity in the water layer, extractable and non-extractable radioactivity in sediment and volatile radioactivity) were between 88.4% to 97.7%

Validity criteria fulfilled:

yes

Description of key information

DT₅₀ and DT₉₀ values (at 12°C) for the decline of test item from the water, the sediment and from the total aquatic sediment system are shown below. These values does not provide the final mineralisation of the substance.

	Calwich Abbey Lake		Emperor Lake
	DT50 (days)	DT90 (days)	DT50 (days)	DT90 (days)
Water	3.71	12.3	4.29	60.7
Sediment	759	2520	>10000	>10000
Total system	5020	>10000	6630	>10000

Only minor degradation is observed indeed, volatile radioactivity, almost all associated with ¹⁴CO_2, accounted for a maximum mean of 13.6% applied radioactivity after 99 days.

 

Key value for chemical safety assessment

Half-life in freshwater:

4.29 d

at the temperature of:

12 °C

Half-life in freshwater sediment:

10 000 d

at the temperature of:

12 °C

Whole System

Half-life in whole system:

6 630 d

at the temperature of:

12 °C

Type of system:

fresh water and sediment

Additional information

The biodegradation of  (Z)-N-octadecyldocos-13-enamide (CAS 10094-45-8) has been studied in two natural aquatic sediment systems under laboratory conditions following OECD 308 guidance (Covance, 2021) at 12 °C. The degradation of 14C-labelled test item was measured in water and sediment and DT50-values were derived. The sediment from Emperor Lake was a sandy clay loam with an acidic pH and low organic carbon content while that from Calwich Abbey Lake was a neutral silt loam with a higher organic carbon content.  Samples of each aquatic sediment system were allowed to acclimatize before being treated with [14C]-test item at a rate of 0.01 mg/L based on the amount of water in the test vessel including that present within the sediment.  The samples were incubated under aerobic conditions at about 12°C in darkness for periods of up to 99 days.

Mean total recoveries of radioactivity (mass balances) for both aquatic sediments were between 88.4% and 97.7% applied radioactivity except at time zero (75.8 to 79.9%).  

In Calwich Abbey Lake aquatic sediment, the radioactivity in the water layer declined from a mean of 85.7% applied radioactivity at Day 1 to not-detected after 99 days of incubation.  In sediment, the total radioactivity increased to a mean of 80.6% applied radioactivity after 28 days and remained at a similar level up to 99 days.  The proportion of radioactivity remaining unextracted in the sediment increased to a mean of 4.1% applied radioactivity after 60 days and then remained at a similar level up to 99 days.  Volatile radioactivity, almost all associated with ¹⁴CO₂, accounted for a maximum mean of 12.9% applied radioactivity after 99 days.

Dissipation of radioactivity from the water was slower in the Emperor Lake aquatic sediment.  The radioactivity in the water layer declined from a mean of 80.2% applied radioactivity at Day 1 to 2.3% after 99 days of incubation.  In sediment, the total radioactivity increased to a mean of 77.6% applied radioactivity after 60 days and remained at a similar level up to 99 days. The proportion of radioactivity remaining unextracted in the sediment increased to a mean of 6.4% applied radioactivity after 99 days.  Volatile radioactivity, almost all associated with ¹⁴CO_2, accounted for a maximum mean of 13.6% applied radioactivity after 99 days.

DT₅₀ and DT₉₀ values for the decline of test item from the water, the sediment and from the total aquatic sediment system are shown below.

	Calwich Abbey Lake		Emperor Lake
	DT50 (days)	DT90 (days)	DT50 (days)	DT90 (days)
Water	3.71	12.3	4.29	60.7
Sediment	759	2520	>10000	>10000
Total system	5020	>10000	6630	>10000

 

Test item was degraded to 2 low level unidentified degradates (≤0.5% applied radioactivity), incorporated into bound (non-extractable) radioactivity and mineralized to carbon dioxide.