(Z)-tetrahydro-6-(2-pentenyl)-2H-pyran-2-one

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:

21 October 1991 to 24 December 1991

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

other: Kanpogyo Notification No. 5, PAB Notification No. 615, and 49 Notification from Basic Industries Bureau No. 392 in 1974

Deviations:

not specified

GLP compliance:

yes

Specific details on test material used for the study:

SOURCE OF TEST MATERIAL
- Lot No.of test material: F901024D1
- Purity: 99.7 %
- Appearance: Transparent colorless liquid

STABILITY AND STORAGE CONDITIONS OF TEST MATERIAL
- Stability under test conditions: Stable
- Solubility and stability of the test substance in the solvent/vehicle: Soluble in alcohol and acetone

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, non-adapted

Details on inoculum:

- Concentration of sludge: 4000 mg/l

Duration of test (contact time):

ca. 28 d

Initial conc.:

100 mg/L

Based on:

test mat.

Parameter followed for biodegradation estimation:

DOC removal

Details on study design:

TEST CONDITIONS
- Composition of medium: test substance + sludge + basal culture medium
- Test temperature: 25 ± 1 °C
- Volume: 300 mL
- Concentration: Test substance and aniline* (reference substance); 100 mg/L
Standard activated sludge; 30 mg/L
- pH: It was measured.

TEST METHOD
The biochemical oxygen demand (BOD) for 28 days and the concentrations of dissolved organic carbon (DOC) of test substance and its hydrolysate were measured. The biodegradability of test substance was evaluated.

TEST SYSTEM
No.1: Test system for confirmation of biodegradation activity (aniline + sludge + basal culture medium)
Basal culture medium was placed in a cultivation bottle and 29 µL (30 mg) of aniline was added to it with a micro syringe and it was mixed. Then sludge was added to it.
No.2: Test system for sludge basal respiration (sludge + basal culture medium)
Basal culture medium and sludge to were mixed in a cultivation bottle.
No.3 - No.5: Test system for biodegradation of test substance (test substance + sludge + basal culture medium)
Basal culture medium was placed in cultivation bottles ad 30 mg of test substance was added and contents were measured. Then sludge was added to each cultivation bottle.
No.6: Test system for stability in water (test substance + Millipore water)
Add 30 mg of test substance measured in a glass cup to 300 ml of Millipore water (more than 10 Mohm-cm of deionized water refined with Milli-Q).
(The volume of a basal culture medium is 300 ml minus the volume of added sludge suspension)

SAMPLING:
- A sample of 10 ml was centrifuged at 1000×g for 10 minutes in order to remove sludge. Then 5 ml of supernatant was taken and poured it into a sample bottle. Then, the supernatant was injected into a total organic carbon analyzer and DOC concentration was measured.

CONTROL AND BLANK SYSTEM
- Please refer to Test Sysem paragraph mentioned above.

Reference substance:

aniline

Key result

Parameter:

% degradation (O2 consumption)

Value:

>= 81 - <= 83

Sampling time:

28 d

Key result

Parameter:

% degradation (DOC removal)

Value:

>= 98 - <= 99

Sampling time:

28 d

Results with reference substance:

BOD biodegradability of aniline was 64% on the 7th day. Therefore, the activity of sludge was considered to be excellent.

Results of observation of contents in cultivation bottles after BOD measurement

The liquid was cloudy in the test system for confirmation of biodegradation activity (No. 1). The liquid was colorless and transparent in the test systems for sludge basal respiration (No. 2), for biodegradation of test substance-1, 2, 3 (No. 3, 4, 5), and for stability in water (No. 6).

Sludge growth was observed in the test systems for confirmation of biodegradation activity and for biodegradation of test substance, compared to the test system for sludge basal respiration.

 

Results of pH measurement

The pH values of test solutions after the measurement of BOD were all 7.1 in the test system for biodegradation of test substance and 4.3 in the test system for stability in water.

Biodegradation activity of sludge

BOD biodegradability of aniline was 64% on the 7th day. Therefore, the activity of sludge was considered to be excellent.

5.7     Measured value of the concentration of hydrolysate

1)  Measurement of purity

According to the sponsor, JLN-COOH in the reference standard for the hydrolysate is likely to cyclize and change back to the test substance during storage. Therefore, we calculated the purity of JLN-COOH in the standard solution of reference standard for the hydrolysate at the time of measurement of JLN-COOH concentration after the measurement of BOD.

Comparing HPLC chromatograms of the standard solution of reference standard for the hydrolysate and in the test system for sludge basal respiration, we concluded that the peaks at 2.14, 2.39, 2.97 and 9.04 minutes in retention time of standard solution were the peaks from the substance contained in the provided reference standard for the hydrolysate.

2)  Result of quantification

JLN-COOH was not detected in the test system for biodegradation of test substance. On the other hand, it was detected at the concentration of 112.8 mg/l in the test system for stability in water, the value of which was equivalent to the theoretically generated concentration (110.7 mg/l) of JLN-COOH calculated from the following equation.

Biodegradability from the concentration of the residual test substance

Against the initial feed concentration (100 mg/l), no test substance was detected in the test system for biodegradation of test substance but it was detected at the concentration of 22.3 mg/l in the test system for stability in water. The biodegradability from the concentration of the residual test substance was not calculated because the concentration of the residual test substance in the test system for stability in water was decreased to 22% of the initial feed concentration.

Results of measurements (values on 28th day)

Item	Test system for biodegradation of test substance*			Test system for stability in water	Theoretical values of initial feed concentration
	1	2	3
BOD, mg	61.6	60.1	60.4	0.0	74.2
DOC concentration, mg/l	1.8	1.3	0.9	72.1	71.4
Test substance, mg/l	< 1	< 1	< 1	22.3	100.0
JLN-COOH, mg/l	< 9	< 9	< 9	112.8	110.7

*) Adjusted values in test system for sludge basal respiration

 

Biodegradability on 28th day

Type of biodegradability	Test system for biodegradation of test substance
	1	2	3
BOD biodegradability, %	83	81	81
DOC biodegradability, %	98	98	99
Biodegradability from the concentration of the residual test substance, %	Not calculated because the concentration of the residual test substance in the test system for stability in water was decreased to 22% of the initial feed concentration.

In the test system for stability in water, DOC was detected at the degree equivalent to the initial feed concentration, while the test substance was detected only at the concentration of 22.3 mg/L against the initial feed concentration (100 mg/L) in GC analysis of the concentration of the residual test substance. On the other hand, JLN-COOH, the product of hydrolysis of test substance, was detected at the degree equivalent to the theoretically generated concentration in its HPLC analysis.

According to the sponsor, JLN-COOH could easily cyclize and change back to the test substance. Therefore, part of JLN-COOH might have cyclized and changed back to the test substance during the GC analysis and have been detected as the test substance in the test system for stability in water.

Validity criteria fulfilled:

yes

Interpretation of results:

readily biodegradable

Conclusions:

In the test system for biodegradation of test substance, BOD and DOC biodegradabilities were 81 to 83% and 98 to 99% respectively, and the test substance and its hydrolysis product, JLN-COOH, were not detected. Therefore, the biodegradability of test substance was considered to be excellent.

Description of key information

In the test system for biodegradation of test substance, BOD and DOC biodegradabilities were 81 to 83% and 98 to 99% respectively, and the test substance and its hydrolysis product were not detected. Therefore, the test substance was considered to be readily biodegradable.

Key value for chemical safety assessment

Biodegradation in water:

readily biodegradable

Type of water:

freshwater