N,N-bis(2-hydroxyethyl)-3-[(C16-18)alkoxy]-1-propanamine

Biodegradation in water: screening tests

Link to relevant study record(s)

Reference

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

experimental study

Adequacy of study:

key study

Study period:

STUDY INITIATION DATE: August 03, 2007 STUDY COMPLETION DATE: November 13, 2007

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 301 B (Ready Biodegradability: CO2 Evolution Test)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Specific details on test material used for the study:

Name: EC#930-859-5
Lot Number: 30038-47; 0463586
CAS Number: Not Given
Physical Description: Solid
Expiration Date: June 2009
Purity: 92%
Storage Conditions: Ambient
Carbon Content: 72.55% (as determined by elemental analysis)

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, non-adapted

Details on inoculum:

Activated sludge was collected from Denton Wastewater Treatment Plant, Denton, Maryland on August 22, 2007. The Denton facility treats predominantly residential wastes. The sludge was sieved using a 2-mm screen and then aerated for approximately four hours. After the aeration period, an aliquot of the sludge was homogenized in a blender at medium speed for approximately two minutes and then allowed to settle for approximately 30 minutes. The supernatant was used as the inoculum the same day that it was prepared. A total suspended solids measurement and standard plate count were performed on the inoculum. Plates were incubated at 20±3ºC for approximately 48 hours.

Duration of test (contact time):

28 d

Initial conc.:

10 other: nominal concentration of approximately 10 mg C/L

Based on:

test mat.

Parameter followed for biodegradation estimation:

CO2 evolution

Details on study design:

Please see "Any other information on materials and methods incl. tables"

Reference substance:

other: Sodium benzoate

Key result

Parameter:

% degradation (CO2 evolution)

Remarks:

The final mean percent biodegradation for the test substance for Method 1 was 56.8%

Value:

56.8

Sampling time:

28 d

Remarks on result:

other: The test substance may not be considered readily biodegradable since the pass level of 60% TCO2 was not achieved within 10 days of achieving 10% TCO2.

Remarks:

The test substance may not be considered readily biodegradable since the pass level of 60% TCO2 was not achieved within 10 days of achieving 10% TCO2. Although the test substance did not prove to be readily biodegradable, its mineralization half-life of less than 28 days (Method 1) demonstrated that the material is subject to biodegradation.

Key result

Parameter:

% degradation (CO2 evolution)

Remarks:

The final mean percent biodegradation for the test substance for Method 2 was 21.2%.

Value:

21.2

Sampling time:

28 d

Remarks on result:

other: The test substance may not be considered readily biodegradable since the pass level of 60% TCO2 was not achieved within 10 days of achieving 10% TCO2.

Remarks:

The test substance may not be considered readily biodegradable since the pass level of 60% TCO2 was not achieved within 10 days of achieving 10% TCO2. Although the test substance did not prove to be readily biodegradable, its mineralization half-life of less than 28 days (Method 1) demonstrated that the material is subject to biodegradation.

Details on results:

Carbon Analysis
The measured total organic carbon (TOC) concentration of the reference substance stock solution was 400.0 mg C/L. The volume of stock solution used to dose the reference chambers was adjusted based on the measured TOC value so that approximately 10 mg C/L was delivered.

Observations and Measurements
The temperature range recorded during the test was 19.8 to 21.3ºC and was within the protocol specified range throughout the test. The results of the standard plate count and TSS measurement performed on the inoculum were 6.6 x 105 CFU/mL and 1080 mg/L, respectively.

The measured dissolved organic carbon (DOC) on Day 29 and pH values of the test chamber contents on Day 28 are presented in Table 1. The measured concentrations of inorganic carbon in the carbon dioxide trapping solutions are presented in Table 2. The cumulative amounts of CO2 produced over the test period are presented in Tables 3 and 4. The cumulative percent of theoretical carbon dioxide (% TCO2) evolved is presented in tabular and graphical forms in Tables 5 and 6 and Figures 1 and 2, respectively.

The control chambers evolved an average of 28.6 mg CO2 over the test period for Method 1. The control chambers evolved an average of 31.0 mg CO2 over the test period for Method 2. These value have been corrected for the amount of CO2 in the trapping solution since potassium hydroxide solution, even when freshly prepared, contains carbonates. The amount of CO2 evolved by the control chambers did not exceed the 40 mg/L (120 mg total) value considered the acceptable limit for CO2 evolution tests (2).

For vessels dosed using Method 1, the viability of the inoculum and validity of the test were supported by the results of the reference substance, sodium benzoate, from which an average of 96.1% of theoretical CO2 was evolved. An average percent biodegradation of greater than 60% was achieved by Day 7, thereby fulfilling the criteria for a valid test by reaching the pass level by Day 14

(1). The final mean percent biodegradation for the test substance was 56.8%. The test substance may not be considered readily biodegradable, since the pass level of 60% TCO2 was not achieved within 10 days of reaching 10% TCO2. For vessels dosed using Method 2, the viability of the inoculum and validity of the test were supported by the results of the reference substance, sodium benzoate, from which an average of 89.6% of theoretical CO2 was evolved. An average percent biodegradation of greater than 60% was achieved by Day 12, thereby fulfilling the criteria for a valid test by reaching the pass level by Day 14 (1). The final mean percent biodegradation for the test substance was 21.2%. The test substance may not be considered readily biodegradable, since the pass level of 60% TCO2 was not achieved within 10 days of reaching 10% TCO2.

Dissolved Organic Carbon (DOC) and pH of Test Solutions at Test Termination

 

                                                                              DOC (1)

Test Chamber (Nominal Concentration)                  (mg C/L)                       pH

                Method 1

Control Rep. 1                                                            <1.0                                7.2

Control Rep. 2                                                            <1.0                                7.2

Sodium Benzoate Rep. 1 (10 mg C/L)                         <1.0                                7.3

Sodium Benzoate Rep. 2 (10 mg C/L)                         <1.0                                7.3

Treatment Rep. 1 (10 mg C/L)                                       1.9                                7.1

Treatment Rep. 2 (10 mg C/L)                                       2.6                                7.1

TOX Control                                                                 1.9                                7.2

Method 2

Control Rep. 1                                                             <1.0                                7.1

Control Rep. 2                                                             <1.0                                7.2

Sodium Benzoate Rep. 1 (10 mg C/L)                         <1.0                                7.2

Sodium Benzoate Rep. 2 (10 mg C/L)                         <1.0                                7.2

Treatment Rep. 1 (10 mg C/L)                                     <1.0                                7.1

Treatment Rep. 2 (10 mg C/L)                                     <1.0                                7.0

TOX Control                                                               <1.0                                7.2

(1) Samples were filtered (0.45 µm) and acidified with two drops 2N HCl prior to analysis.

Please see attached Tables & Figures FOR FULL TABLES ETC.

Validity criteria fulfilled:

yes

Interpretation of results:

inherently biodegradable, not fulfilling specific criteria

Remarks:

The test substance may not be considered readily biodegradable since the pass level of 60% TCO2 was not achieved within 10 days of achieving 10% TCO2. Although the test substance did not prove to be readily biodegradable, its mineralization half-life of less than 28 days (Method 1) demonstrated that the material is subject to biodegradation.

Conclusions:

Evidence of ready biodegradability in a Carbon Dioxide Evolution Test is 60% TCO2 within a 28-day test period. In addition, the pass level must be reached within 10 days of achieving 10% TCO2 . The final mean percent biodegradation for the test substance for Method 1 was 56.8% and for Method 2 was 21.2%. The test substance may not be considered readily biodegradable since the pass level of 60% TCO2 was not achieved within 10 days of achieving 10% TCO2. Although the test substance did not prove to be readily biodegradable, its mineralization half-life of less than 28 days (Method 1) demonstrated that the material is subject to biodegradation.

Executive summary:

The ready biodegradability of EC#930-859-5 was determined by the Carbon Dioxide Evolution Test Method (OECD Guideline 301B). Tests of ready biodegradability are stringent tests that provide limited opportunity for acclimation and biodegradation to occur. In the CO2 test, inoculated mineral medium was dosed with a known amount of test substance as the nominal sole source of organic carbon and aerated with CO2-free air. The CO2 produced from the mineralization of organic carbon within the test chambers was displaced by the flow of CO2-free air and trapped as K2CO3 in KOH trapping solution. The amount of CO2 produced by the test substance (corrected for that evolved by the blank inoculum) is expressed as a percentage of the theoretical amount of CO2 (TCO2) that could have been produced if complete biodegradation of the test substance occurred. The test was conducted using two different techniques (without and with adsorption to silica gel) for administering the test substance and contained a blank control group, a reference group, and a treatment group, each containing two replicate test chambers and a toxicity control for each technique. The blank control was used to measure the background CO2 production of the inoculum and was not dosed with a carbon source. The reference chambers were dosed with sodium benzoate, a substance known to be biodegradable, at a nominal concentration of 10 mg C/L.         

The treatment group test chambers were used to evaluate EC#930-859-5 at a nominal  concentration of approximately 10 mg C/L. The toxicity control was used to evaluate toxicity of the test substance to the inoclum and was dosed with both the reference and test substances at 10 mg C/L. For vessels dosed using Method 1 (without silica gel), the results indicated that the activated sludge inoculum was active, degrading the reference substance 96.1%. The average cumulative percent biodegradation for  EC#930-859-5 was 56.8%. The toxicity control evolved 75.5%. For vessels dosed using Method 2 (with silica gel), the results indicated that the activated sludge inoculum was active, degrading the reference substance 89.6%. The average cumulative percent biodegradation for EC#930-859-5 was 21.2%. The toxicity control evolved 55.3%.

Although the test substance did not prove to be readily biodegradable, its mineralization half-life of less than 28 days (Method 1) demonstrated that the material is subject to biodegradation.

 

 

                                             Average Cumulative                      Average                             Readily

Test Substance                Percent Biodegradation(1)         Final pH(1)                      Biodegradable(2)

 EC#930-859-5   (Method 1)        56.8                                      7.1                                        No

EC#930-859-5    (Method 2)        21.2                                      7.1                                        No

(1)  Average of two replicates.

(2)  Meets or exceeds the OECD criteria for ready biodegradability (60% of TCO2 within a 10-day

 window of reaching 10% TCO2).

Description of key information

The test substance is not readily biodegradable, although the test substance did not prove to be readily biodegradable, its mineralization half-life of less than 28 days (Method 1) demonstrated that the material is subject to biodegradation.

Key value for chemical safety assessment

Biodegradation in water:

inherently biodegradable, not fulfilling specific criteria

Additional information

The ready biodegradability of EC#930-859-5 was determined by the Carbon Dioxide Evolution Test Method (OECD Guideline 301B). Tests of ready biodegradability are stringent tests that provide limited opportunity for acclimation and biodegradation to occur. In the CO2 test, inoculated mineral medium was dosed with a known amount of test substance as the nominal sole source of organic carbon and aerated with CO2-free air. The CO2 produced from the mineralization of organic carbon within the test chambers was displaced by the flow of CO2-free air and trapped as K2CO3 in KOH trapping solution. The amount of CO2 produced by the test substance (corrected for that evolved by the blank inoculum) is expressed as a percentage of the theoretical amount of CO2 (TCO2) that could have been produced if complete biodegradation of the test substance occurred. The test was conducted using two different techniques (without and with adsorption to silica gel) for administering the test substance and contained a blank control group, a reference group, and a treatment group, each containing two replicate test chambers and a toxicity control for each technique. The blank control was used to measure the background CO2 production of the inoculum and was not dosed with a carbon source. The reference chambers were dosed with sodium benzoate, a substance known to be biodegradable, at a nominal concentration of 10 mg C/L.         

The treatment group test chambers were used to evaluate EC#930-859-5 at a nominal  concentration of approximately 10 mg C/L. The toxicity control was used to evaluate toxicity of the test substance to the inoclum and was dosed with both the reference and test substances at 10 mg C/L. For vessels dosed using Method 1 (without silica gel), the results indicated that the activated sludge inoculum was active, degrading the reference substance 96.1%. The average cumulative percent biodegradation for  EC#930-859-5 was 56.8%. The toxicity control evolved 75.5%. For vessels dosed using Method 2 (with silica gel), the results indicated that the activated sludge inoculum was active, degrading the reference substance 89.6%. The average cumulative percent biodegradation for EC#930-859-5 was 21.2%. The toxicity control evolved 55.3%.

Although the test substance did not prove to be readily biodegradable, its mineralization half-life of less than 28 days (Method 1) demonstrated that the material is subject to biodegradation.

 

 

                                             Average Cumulative                      Average                             Readily

Test Substance                Percent Biodegradation(1)         Final pH(1)                      Biodegradable(2)

 EC#930-859-5   (Method 1)        56.8                                      7.1                                        No

EC#930-859-5    (Method 2)        21.2                                      7.1                                        No

(1)  Average of two replicates.

(2)  Meets or exceeds the OECD criteria for ready biodegradability (60% of TCO2 within a 10-day

 window of reaching 10% TCO2).