Dipropoxymethane

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:

From 2010-05-20 to 2010-06-18

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 301 D (Ready Biodegradability: Closed Bottle Test)

Version / remarks:

Adopted 17 July 1992

Qualifier:

according to guideline

Guideline:

EU Method C.4-E (Determination of the "Ready" Biodegradability - Closed Bottle Test)

GLP compliance:

yes (incl. QA statement)

Oxygen conditions:

aerobic

Inoculum or test system:

sewage, predominantly domestic (adaptation not specified)

Details on inoculum:

The inoculum contained a mixed population of microorganisms obtained from the secondary effluent of wastewater treatment plant of Pardubice processing predominantly municipal sewage. The fresh collected wastewater was filtered through paper filter. COD was determined and wastewater was aerated till using. The inoculum preparation is in conformity with the recommendations of the test guidelines.
The volume of wastewater for the inoculation of mineral medium was 2.0 ml per 1 L of medium.

Duration of test (contact time):

28 d

Initial conc.:

3.35 mg/L

Based on:

COD

Parameter followed for biodegradation estimation:

O2 consumption

Details on study design:

The test substance in mineral medium is inoculated with a relatively small number of microorganisms from a mixed population and kept in completely full closed bottles in the dark at constant temperature (2 x 9 bottles).
The following determinations were done simultaneously under the same conditions:
- check of inoculum activity with the reference substance (2 x 9 bottles)
- toxicity test with test and reference substance mixture and inoculated medium (2 x 5 bottles)
- determination of blank (inoculated mineral medium) (2 x 9 bottles)

The bottles were placed into thermostat (20 +/- 1 °C).

Degradation is determined by analysis of dissolved oxygen over a 28-day period.
The zero-time bottles were analysed immediately for dissolved oxygen by the Winkler method.
At the 3rd, 7th, 10th, 14th, 17th, 21st, 24th and 28th day of test, the appropriate bottles from each series were taken off and they were analysed for dissolved oxygen.

Mineral medium was prepared as recommended in the OECD TG 301 D.

Reference substance:

benzoic acid, sodium salt

Preliminary study:

No preliminary study was performed.

Test performance:

There were no deviations from study plan or guidelines during the study.

Parameter:

% degradation (O2 consumption)

Value:

14.3

Sampling time:

28 d

Details on results:

The oxygen consumption and percentage of the biodegradation of test substance for each test interval and each bottle were calculated (Tables 1 to 4).
The following test validity criteria were fulfilled: (1) Oxygen depletion in the inoculum blank did not exceed 1.5 mg/L after 28 days, (2) The residual concentration of oxygen in the test did not fall below 0.5 mg/L in any time, (3) The difference of extremes of replicate values of the removal of test substance at the end of the test was less than 20%, (4) The percentage degradation of the reference substance reached the level for ready biodegradability by 14 days, (5) In the toxicity test, containing both the test substance and the reference chemical, more than 25% degradation occured in 14 days. The test substance was therefore not inhibitory the inoculum.

Results with reference substance:

Degradation of 76.3% of reference substance was attained at the end of the study (Table3)

Table 1 – Determination of dissolved oxygen concentration in the main test

Concentration		Dissolved oxygen (mg/L) after period (days)
		0	3	7	10	14	17	21	24	28
Test substance Cz	Serie 1	8.56	8.50	8.41	8.00	7.97	7.97	7.82	7.69	7.68
	Serie 2	8.56	8.50	8.41	7.98	7.95	7.97	7.82	7.72	7.68
	Average	8.56	8.50	8.41	7.99	7.96	7.97	7.82	7.71	7.68
Reference substance Cr	Serie 1	8.46	6.41	6.32	6.01	5.75	5.60	5.61	5.47	5.42
	Serie 2	8.46	6.41	6.32	6.01	5.75	5.62	5.58	5.47	5.45
	Average	8.46	6.41	6.32	6.01	5.75	5.61	5.60	5.47	5.44
Blank experiment C0	Serie 1	8.48	8.54	8.53	8.34	8.33	8.23	8.11	8.05	8.07
	Serie 2	8.46	8.51	8.50	8.34	8.33	8.23	8.11	8.05	8.07
	Average	8.47	8.53	8.52	8.34	8.33	8.23	8.11	8.05	8.07

 

Table 2 - Determination of dissolved oxygen concentration in the toxicity test

Concentration		Dissolved oxygen (mg/L) after period (days)
		0	3	7	10	14
Test + reference substance C (z+r)	Serie 1	8.54	6.45	6.26	5.92	5.81
	Serie 2	8.52	6.45	6.26	5.90	5.81
	Average	8.53	6.45	6.26	5.91	5.81
Blank experiment C0	Serie 1	8.48	8.54	8.53	8.34	8.33
	Serie 2	8.46	8.51	8.50	8.34	8.33
	Average	8.47	8.53	8.52	8.34	8.33

 

Table 3 – Biodegradation of test and reference substance in the main test

Concentration		Biodegradation (%) after period (days)
		0	3	7	10	14	17	21	24	28
Test substance (Dt)	Serie 1	0	3.4	5.8	12.8	13.4	10.4	11.3	13.4	14.3
	Serie 2	0	3.4	5.8	13.4	14.0	10.4	11.3	12.5	14.3
	Average	0	3.4	5.8	13.1	13.7	10.4	11.3	13.0	14.3
Reference substance (Dt)	Serie 1	0	61.2	63.5	67.4	74.7	76.2	72.4	74.7	76.7
	Serie 2	0	61.2	63.5	67.4	74.7	75.6	73.3	74.7	75.9
	Average	0	61.2	63.5	67.4	74.7	75.9	72.8	74.7	76.3

 

For the test substance, the following formula was used to calculate the biodegradation percentage: Dt = ((Cz0 – Cz1)-(C00-C01)-Cn1) x 100 / CODz0

 

For the reference substance, the following formula was used to calculate the biodegradation percentage: Dt = ((Cr0 – Cr1)-(C00-C01)) x 100 / CODr0

 

 

Table 4 - Biodegradation of test and reference substance in the toxicity test

Concentration		Biodegradation (%) after period (days)
		0	3	7	10	14
Test + reference substance (Dt)	Serie 1	0	31.6	34.2	36.7	38.1
	Serie 2	0	31.3	33.9	36.7	37.8
	Average	0	31.4	34.1	36.7	38.0

 

For the test + reference substance, the following formula was used to calculate the biodegradation percentage: Dt = ((C(z+r)0 - C(z+r)1)+(C00-C01)) x 100 / COD (z+r)0

Validity criteria fulfilled:

yes

Interpretation of results:

not readily biodegradable

Conclusions:

In this 28-day study of ready biodegradability, the degradation of 14.3% of the test substance propylal was attained in the end of the study.

Executive summary:

The test substance, propylal, was tested for the ready biological degradability in Closed Bottle test.

The test was performed according to: Method C.4E – Closed Bottle Test, Council Regulation (EC) No 440/2008, published in O.J.L 142, 2008.

 

The results of biological degradation are related to experimentally determined COD values of test and reference substance at the beginning of the test.

The test substance had sufficient solubility in used mineral medium. The dosage from the stock solution was carried out.

Sodium benzoate was used as the reference substance. The dosage was carried out from the stock solution.

COD of the test substance in medium at the beginning of the main test: 3.35 mg/L.

COD of reference substance in medium at the beginning of the main test: 3.44 mg/L.

In parallel to the main test the toxicity test was performed.

As the test substance has not any contents of nitrogen in the chemical composition, oxidized nitrogen forms were not determined and the correction for nitrification was not carried out.

The test was performed at temperature of 20 ± 1°C with the pH values of solutions 7-8 at the beginning of the test.

 

The prescribed validity criteria in the test were fulfilled. The test substance was not inhibiting for the used inoculum. Since all criteria of acceptability were met, this study is considered to be valid.

 

In this 28-day study of ready biological degradability, the degradation of 14.3% of the test substance, propylal, was attained in the end of study. 

Description of key information

In a 28-day closed bottle test performed according to OECD TG 301D, degradation of 14.3% of Dipropoxymethane was attained at the end of the study.

Key value for chemical safety assessment

Biodegradation in water:

under test conditions no biodegradation observed