N,N-bis(2-ethylhexyl)formamide

Biodegradation in water: screening tests

Administrative data

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

experimental study

Adequacy of study:

key study

Study period:

10 Dec 2019 - 12 Feb 2020

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2020

Report date:

2020

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 301 C (Ready Biodegradability: Modified MITI Test (I))

Version / remarks:

1992

GLP compliance:

yes (incl. QA statement)

Test material

Test material information

Constituent 1

Reference substance name:

N,N-bis(2-ethylhexyl)formamide

EC Number:

860-695-9

Cas Number:

88247-41-0

Molecular formula:

C17H35NO

IUPAC Name:

N,N-bis(2-ethylhexyl)formamide

Test material form:

liquid

Study design

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge (adaptation not specified)

Details on inoculum:

- Source of inoculum/activated sludge (e.g. location, sampling depth, contamination history, procedure): Standard activated sludge obtained from the Chemicals Evaluation and Research Institute, Japan
- Date of receipt: November 21, 2019
- Concentration of sludge: 2300 mg/L mixed liqor suspended solids (MLSS)
- Initial cell/biomass concentration: inoculum concentration = 30 mg/L

Duration of test (contact time):

28 d

Initial test substance concentration

Initial conc.:

100 mg/L

Based on:

test mat.

Parameter followed for biodegradation estimation

Parameter followed for biodegradation estimation 1

Parameter followed for biodegradation estimation:

test mat. analysis

Parameter followed for biodegradation estimation 2

Parameter followed for biodegradation estimation:

O2 consumption

Parameter followed for biodegradation estimation 3

Parameter followed for biodegradation estimation:

DOC removal

Details on study design:

TEST CONDITIONS
- Composition of medium: Standard mineral medium according to OECD guideline
- Test temperature: 25 +/- 1 °C
- pH: 7 +/- 0.04
- pH adjusted: yes
- Suspended solids concentration: 2300 mg/L mixed liquor suspended solids (MLSS)

TEST SYSTEM
- Culturing apparatus: Closed system apparatus for measuring oxygen consumption, OM-3100A, 300 mL glass bottles
- Number of culture flasks/concentration: 3
- Method used to create aerobic conditions: continuous stirring with magnetic stirrer
- Measuring equipment: BOD measurements apparatus, TOC analyzer, GC for analytical determination of residual test substance, pH meter
- Details of trap for CO2 and volatile organics if used: soda lime

SAMPLING
- Sampling frequency: at start of the BOD measurement pH values were measured in the inoculum blank and abiotic control, at the end of BOD measurements pH was measured in all test solutions; DOC measurement was conducted in abiotic control, test solutions, and inoculum blank after the end of the BOD measurement at day 28;
- Sampling method: For DOC measurement 12 mL of test solution were sampled

CONTROL AND BLANK SYSTEM
- Inoculum blank: 1
- Abiotic sterile control: 1
- Reference control: 1

Reference substance

Reference substance:

aniline

Results and discussion

% Degradation

% Degradation 1

Parameter:

% degradation (O2 consumption)

Value:

0

Sampling time:

28 d

Remarks on result:

other:

Remarks:

results based on BOD

% Degradation 2

Parameter:

% degradation (test mat. analysis)

Value:

>= 0 - <= 1

Sampling time:

28 d

Remarks on result:

other:

Remarks:

The degradability based on residual analysis of the test material was 0, 1, and 1% in the three samples

Details on results:

The degradability based on DOC after 28 days was not calculated since the test substance was insoluble in water and the DOC in the abiotic blank after 28 days was less than 90% of the theoretical value.
Since the biodegradation based on residual analysis of the test substance showed approximately 1% degradation and no additional peak was detected on the GC chromatogram, it was conluded that the test substance was not transformed.

BOD5 / COD results

Results with reference substance:

The biodegradation based on BOD measurements was 60% after 7 days and 85% after 28 days for the reference substance aniline.

Any other information on results incl. tables

Table 1. Measured BOD and pH values

Bottle No.	Sample	BOD (mgO2)				pH
		Day 7	Day 14	Day 21	Day 28	Day 0	Day 28
1	Abiotic control	0.1	0.1	0.1	0.1	7.7	7.7
2	Test item 1	2.0	4.1	4.1	4.1	-	7.2
3	Test item 2	2.3	4.6	4.7	4.7	-	7.2
4	Test item 3	2.5	4.6	4.7	4.7	-	7.1
5	Reference control	50.0	73.2	75.7	78.8	-	7.9
6	Inoculum blank	6.5	11.8	12.2	12.5	7.0	7.3

 

Table 2. Corrected measured values at day 28

	Test item			Abiotic control	Theoretical value
	Bottle No. 2	Bottle No. 3	Bottle No. 4
BOD (mgO2)*	- 8.4	- 7.8	-7.8	0.1	94.4
DOC*	0.1	0.2	0.4	0.4	22.7
Residue analysis (mg)	30.9	30.4	30.5	30.8	30.0
Residue analysis (%)	103	101	102	103	-

* values of the test item were corrected for BOD or DOC values of the inoculum blank

 

Table 3. Biodegradation (%) at day 28

	Test item			Average
	Bottle No. 2	Bottle No. 3	Bottle No. 4
BOD	0 (-9)	0 (-8)	0 (-8)	0
DOC	NA	NA	NA	-
Residue analysis	0	1	1	1

NA = not available, due to insolubility of test item in water (< 90% DOC of test item in abiotic control)

 

Table 4. Validity criteria for OECD 301C

Criterion from the guideline	Outcome	Validity criterion fulfilled
The oxygen uptake of the inoculum blank is normally 20-30 mg O2/L and should not be greater than 60 mg O2/L in 28 days. Values higher than 60 mg/L require critical examination of the data and the experimental technique. If the pH value is outside the range 6-8.5 and the oxygen consumption by the test substance is less than 60%, the test could be repeated with a lower concentration of test substance.	- Oxygen uptake based on BOD was 41.67 mgO2/L at day 28 (12.5 mgO2/0.3 L = 41.67 mgO2/L) - pH was between 7.0 – 7.9 in all vessels	Yes
A test is considered valid if the difference of extremes of replicate values of the removal of the test substance at the plateau or at the end of the test, as appropriate is less than 20% and if the percentage degradation of aniline calculated from the oxygen consumption exceeds 40% after 7 days and 65% after 14 days.	- Differences of extremes of replicate values of biodegradation of test substance = 7% based on corrected BOD - Degradation of aniline at 7 days = 60% and at 28 days = 85%	Yes

Applicant's summary and conclusion

Validity criteria fulfilled:

yes

Remarks:

See Table 4 in 'any other information on results incl. tables'

Interpretation of results:

not readily biodegradable