1,1-dimethoxy-2-phenylethane

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:

29 Jun - 27 Jul 1999

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)

Qualifier:

according to guideline

Guideline:

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

Deviations:

no

GLP compliance:

yes

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, domestic, non-adapted

Details on inoculum:

- Source of inoculum/activated sludge: activated sludge from secondary effluent of a domestic sewage treatment plant (waste water treatment plant Odenthal, Germany); Date of collection: 25 Jun 1999
- Storage conditions: aerated
- Storage length: 4 d
- Pretreatment: separation of coarse particles by filtration
- Concentration of sludge: 5 mL/L (concentration of effluent in reaction mixture)

Duration of test (contact time):

28 d

Initial conc.:

2.9 mg/L

Based on:

test mat.

Parameter followed for biodegradation estimation:

O2 consumption

Details on study design:

TEST CONDITIONS
- Test temperature: 20 ± 1 °C
- Aeration of dilution water: yes
- Suspended solids concentration: 5 mL/L concentration of effluents in reaction mixture
- Continuous darkness: yes

TEST SYSTEM
- Number of culture flasks/concentration: 2
- Method used to create anaerobic conditions: the activated sludge was maintained in an aerobic condition by aeration for 4 h

SAMPLING
- Sampling frequency: 7, 14, 21, 28 days
- Sampling method: oxygen concentration was measured

CONTROL AND BLANK SYSTEM
- Inoculum blank: yes, 2 bottles per sampling
- Toxicity control: yes, 2 bottles per sampling
- Other: Reference control: yes, 2 bottles per sampling
- Abiotic sterile control: no

Reference substance:

benzoic acid, sodium salt

Parameter:

% degradation (O2 consumption)

Value:

0

Sampling time:

28 d

Details on results:

Within the test period of 28 days, a degradation of 0% was determined for the test item. Thus, the test item is not readily biodegradable according to the OECD criteria.

Results with reference substance:

The reference control achieved a degradation of 71% after 14 days.

Biological Results:

Table 1: Results - DO depletion: % Degradation of test substance

Test substance Test concentration: 2.9 mg/L ThOD: 2409 mg/g COD : --- mg/g	DO depletion after n days [mg/L]
	7 d	14 d	21 d	28 d
No.1: (mt0 - mtx) - (mb0 - mbx)	0.00	0.00	0.00	0.00
No.2: (mt0 - mtx) - (mb0 - mbx)	0.00	0.00	0.00	0.00
Dl: % Degradation	0	0	0	0
D2: % Degradation	0	0	0	0
D, Mean	0	0	0	0

 

Table 2: Results - DO depletion: % Degradation of the reference item

Reference substance Test concentration: 2.9 mg/1 ThOD: 1665 mg/g COD : --- mg/g	DO depletion after n days [mg/L]
	7 d	14 d	21 d	28 d
No.1: (mt0 - mtx) - (mb0 - mbx)	3.30	3.40	3.69	3.71
No.2: (mt0 - mtx) - (mb0 - mbx)	3.20	3.50	3.48	3.78
Dl: % Degradation	68	70	76	77
D2: % Degradation	66	72	72	78
D, Mean	67	71	74	78

 

Table 3: Results - DO depletion: % Degradation of toxicity control

*Toxicity control	DO depletion after n days [mg/L]
	7 d	14 d	21 d	28 d
No.1: (mt0 - mtx) - (mb0 - mbx)	3.14	3.57	4.10	3.94
No.2: (mt0 - mtx) - (mb0 - mbx)	3.16	3.85	4.60	4.01
Dl: % Degradation	27	30	35	33
D2: % Degradation	27	33	39	34
D, Mean	27	32	37	34

* In the toxicity control 2.9 mg/L test substance and 2.9 mg/L reference substance were used. The ThOD values respectively COD values of these substances are shown in the tables above.

Validity criteria fulfilled:

yes

Interpretation of results:

under test conditions no biodegradation observed

Conclusions:

The derived 28 d degradation rate was 0% for the test substance and 34% for the toxicity control. Since the test substance did not show any biodegradability within 28 d it is not considered to be readily biodegradable according to the OECD criteria. Due to the fact that the degradation rate of the toxicity control was > 25% after 14 d, toxic effects of the test substance to the inoculum can be excluded.

Description of key information

Not readily biodegradable: 0% within 28 d (OECD 301D)

Key value for chemical safety assessment

Biodegradation in water:

under test conditions no biodegradation observed

Additional information

One GLP guideline study according to OECD 301D is available investigating the ready biodegradability of the substance. A mixed microbial population of the activated sludge of a local municipal STP was inoculated with a nominal concentration of 2.9 mg/L test substance and incubated for 28 d under controlled conditions in the dark. Degradation was followed by the determination of dissolved oxygen content after 0 h, 7, 14, 21 and 28 d. An inoculum blank, a reference control and a toxicity control were run in parallel. The derived 28 d degradation rate was 0% for the test substance and 34% for the toxicity control. Since the test substance did not show any biodegradability within 28 d it is not considered to be readily biodegradable according to the OECD criteria. Due to the fact that the degradation rate of the toxicity control was >25% after 14 d, toxic effects of the test substance to the inoculum can be excluded.