N-benzylprop-2-enamide

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:

07 February 2007 to 18 April 2007

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study with acceptable restrictions

Qualifier:

according to guideline

Guideline:

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

Qualifier:

according to guideline

Guideline:

EU Method C.4-C (Determination of the "Ready" Biodegradability - Carbon Dioxide Evolution Test)

Qualifier:

according to guideline

Guideline:

other: ISO 9439, 1999

GLP compliance:

yes

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, non-adapted

Details on inoculum:

- Source of inoculum/activated sludge: Municipal sewage treatment plant of Waterschap De Maaskant, 's-Hertogenbosch
- Storage conditions: under aeration
- Storage length: not indicated
- Preparation of inoculum for exposure: settled during 30-65 min and decanted to 10 mL/L of mineral medium
- Pretreatment: none
- Concentration of sludge: ss 4.4 g/L (first test), ss 3.7 g/L (second test)
- Water: purified by reverse osmosis and passed over activated carbon and ion exchange cartridges

Duration of test (contact time):

29 d

Initial conc.:

ca. 16 mg/L

Based on:

test mat.

Initial conc.:

ca. 44 mg/L

Based on:

ThCO2

Parameter followed for biodegradation estimation:

CO2 evolution

Remarks:

captured by 2 Ba(OH)2 traps

Details on study design:

TEST CONDITIONS
- Composition of medium: according to OECD 301B
- Solubilising agent: none (direct weighing into 2 L of the medium with microbial organisms and mineral components
- Test temperature: 22.0-23.9 ˚C
- pH: 7.4-7.9
- pH adjusted: no
- Aeration of dilution water: synthetic air (30-100 mL/min)
- Suspended solids concentration: SS test 1 4.4 g/L; test 2 3.7 g/L
- Continuous darkness: yes (darkbrown bottles)

TEST SYSTEM
- Culturing apparatus: 2L darkbrown glass vessel with 3 CO2 absorbers (eaach containing 100 mL 0.0125 M Ba(OH)2) in series
- Number of culture flasks/concentration: 2
- Method used to create aerobic conditions: bubbling of synthetic aire

SAMPLING
- Sampling frequency: every 2-3 days from the first Ba(OH)2 trap during the first 10 days, every fifth day thereafter
- Sample storage before analysis: no data
- Other: on day 0 and 28 pH was measured with phenolphthalein;
On day 28 1 mL HCl (37%) was added to the bottles and after aeration overnight the final titration was done on day 29

CONTROL AND BLANK SYSTEM
- Inoculum blank: 2 bottles
- Toxicity control: 1 bottle
- Substance: 2 bottles
- Positive control (sodium acetate) 1 bottle

STATISTICAL METHODS:

Reference substance:

acetic acid, sodium salt

Parameter:

% degradation (CO2 evolution)

Value:

>= 2 - <= 3

Sampling time:

9 d

Remarks on result:

other: values for test 1 and 2

Parameter:

% degradation (CO2 evolution)

Value:

>= 2 - <= 5

Sampling time:

14 d

Remarks on result:

other: values for test 1 and 2

Parameter:

% degradation (CO2 evolution)

Value:

>= 18 - <= 33

Sampling time:

19 d

Remarks on result:

other: values for test 1 and 2

Remarks:

deviation between the two bottles was > 20% in test 1

Parameter:

% degradation (CO2 evolution)

Value:

>= 46 - <= 59

Sampling time:

23 d

Remarks on result:

other: values for test 1 and 2

Parameter:

% degradation (CO2 evolution)

Value:

>= 67 - <= 79

Sampling time:

29 d

Remarks on result:

other: values for test 1 and 2

Remarks:

deviation between the two bottles was > 20% in both tests

Details on results:

see attached tables
Toxicity controls showed 15% degradation in test 1 and 7% degradation in test 2 on day 14

Results with reference substance:

74% biodegradation on day 14 in both tests

Validity criteria fulfilled:

no

Remarks:

partly see above

Interpretation of results:

inherently biodegradable

Remarks:

the study director concluded that the deviation from the validity criteria has not affected the conclusion of the study

Conclusions:

The substance is considered to be almost readily biodegradable

Executive summary:

In a CO2 evolution test, the substance showed very limited biodegradation until day 14 to 19. Thereafter in test 1 the substance met the 10-window criterion in one of the bottles, but not in the replicate (biodegradation 80 and 56% on day 29). In the second test the substance met the 10-day window in both replicates (biodegrdation 67 and 95% on day 29). The difference between the replicates was > 20% during part of the tests. The toxicity control showed that the substance inhibits bacterial growth.

The results are indicative for ready biodegradability of the substance, although the criteria are not completely met.

Description of key information

In a CO2 evolution test, the substance showed very limited biodegradation until day 14 to 19. Thereafter in test 1 the substance met the 10-window criterion in one of the bottles, but not in the replicate (biodegradation 80 and 56% on day 29). In the second test the substance met the 10-day window in both replicates (biodegrdation 67 and 95% on day 29). The difference between the replicates was > 20% during part of the tests. The toxicity control showed that the substance inhibits bacterial growth.

The results are indicative for ready biodegradability of the substance, although the criteria are not completely met.

Key value for chemical safety assessment

Biodegradation in water:

readily biodegradable

Type of water:

freshwater