1,2-epoxybutane

Biodegradation in water: screening tests

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

other: CO2-Headspace Test according to ISO 14593 (Draft, 1996)

GLP compliance:

yes

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, domestic, non-adapted

Details on inoculum:

- activated sludge from laboratory wastewater plants treating municipal sewage
- concentration of dry substance: 4 mg/L

Duration of test (contact time):

28 d

Initial conc.:

34 mg/L

Based on:

test mat.

Parameter followed for biodegradation estimation:

CO2 evolution

Reference substance:

aniline

Parameter:

% degradation (CO2 evolution)

Remarks:

ca.

Value:

5

Sampling time:

7 d

Parameter:

% degradation (CO2 evolution)

Value:

25

Sampling time:

14 d

Parameter:

% degradation (CO2 evolution)

Value:

73

Sampling time:

21 d

Key result

Parameter:

% degradation (CO2 evolution)

Value:

>= 80 - <= 90

Sampling time:

28 d

Details on results:

- duration of lag phase: ca. 8 -10 days
- duration of degradation phase: ca. 19 - 20 days
- degradation degree in the inhibition control at the end of the test: 80-90 % TIC
- elimination degree in the inhibition control at the end of the test: 90-100 % DOC
- physical-chemical (abiotic) elimination of the test substance at the end of test: - physical-chemical (abiotic) elimination of the test substance at the end of test: <10 % DOC

VALIDITY CRITERIA
- max. deviation of the degradation degree of the test substance in replicates at the end of the test < 20 %: yes
- degradation degree of the reference substance >60 % TIC after 14 days: yes
- inhibition of the inoculum at the test concentration: no
- TIC-value (mg/I) of the blank after 28 days <15 % of the amount of test substance added initially (mg ThIC/I): yes

Results with reference substance:

Kinetic of control substance (in %):
= 68 after 7 day(s)
= 96 after 21 day(s)

Validity criteria fulfilled:

yes

Interpretation of results:

readily biodegradable

Conclusions:

The test item is readily biodegradable according to OECD criteria

Executive summary:

An experimental study was conducted to assess the biodegradability of the test item according to the guideline ISO 14593 (Draft, 1996). 4 mg/l inoculum of activated sludge (municipal sewage) were exposed to a concentration of 34 mg/l test item for 28 d in closed bottes. The CO2 evolution was determined weekly as TIC (Total inorganic carbon). After 28 d 80-90 % degradation was observed. All validity criteria were fulfilled and the test item can be rated as readily biodegradable according to OECD criteria.

Reference 2

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

experimental study

Adequacy of study:

supporting study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 301 A (Ready Biodegradability: DOC Die Away Test)

Principles of method if other than guideline:

The test was exceptionally prepared in a closed test system. Therefore specially designed 1 liter shake flasks were used, which were filled with 500 mL mineral medium and a sufficient amount of test substance. After closing the test flasks the remaining space results into a headspace volume of air.

GLP compliance:

yes

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, domestic, non-adapted

Details on inoculum:

The inoculum consisted of activated sludge mixed liquor collected from the Midland Municipal Wastewater Treatment Plant (Midland, Michigan, USA). The mixed liquor was collected on the day of study initiation and continuously aerated to allow minimization of residual dissolved organic carbon before adding to the reaction vessels. Prior to inoculation of the mineral medium, the average mixed liquor suspended solids (MLSS) concentration was determined to be 1963 mg/L (5). Based on this determination, 6 liters of sterile mineral medium were inoculated with 92 mL of the mixed liquor to yield a final MLSS concentration of 30 mg/L. The pH of the inoculated mineral medium was determined to be 7.3, which is within the required range of 7.2 - 7.6.

Duration of test (contact time):

28 d

Initial conc.:

10 - 40 other: mg DOC/L

Based on:

DOC

Parameter followed for biodegradation estimation:

DOC removal

Details on study design:

The biodegradability of the test item was examined under aerobic conditions using the DOC (dissolved organic carbon) Die-Away Test, OECD Method 301 A. This method consisted of a shake flask biodegradation test with defined medium.

Reference substance:

benzoic acid, sodium salt

Test performance:

Benzoate was readily degraded in the DOC Die-Away Test, OECD Method 301 A. After 3 days, 73% of the DOC as benzoate was removed from the test medium. After 28 days, 92% of the DOC as benzoate was removed demonstrating the viability ofthe inoculum

Parameter:

% degradation (DOC removal)

Value:

90

Sampling time:

28 d

Details on results:

For the test item, an average of 90% DOC as test material was degraded in the viable reaction flasks after 28 days. In this study, loss of DOC as butylene oxide in the viable reaction mixtures did not exceed 10% until after day 5. Butylene oxide cannot be classified as readily biodegradable since >70% DOC removal was not achieved until day 19. DOC removal in the viable reactions was biologically mediated, since the DOC removal in the abiotic controls was <1% at the end of the study (day 28).

Results with reference substance:

98 % DOC removal after 28 d

Validity criteria fulfilled:

yes

Interpretation of results:

readily biodegradable, but failing 10-day window

Conclusions:

At the end of 10 day degradation of the test item was found to be less than 70% but 90% degradation was observed at the end of 28 day.

Executive summary:

The biodegradability of the test item was examined under aerobic conditions using the DOC (dissolved organic carbon) Die-Away Test, OECD Method 301 A. This method consisted of a shake flask biodegradation test with defined medium. For the test item, an average of 90% of the material was degraded in the viable reaction flasks after 28 days. For a compound to reach the "pass level", >70% biodegradation must be reached within 10 days of the start of biodegradation. By definition, biodegradation starts when the percent degradation exceeds the 10% level. In this study, loss of butylene oxide in the viable reaction mixtures exceeded the 10% level at day 5. However, 70% degradation was not achieved until day 19. Therefore, the test item did not meet the OECD criteria for ready biodegradability and cannot be classified as readily biodegradable. Benzoate was included as a positive control to ensure the viability of the inoculum Benzoate was extensively degraded after three days (e.g. 73% removal) thus confirming the viability of the inoculum. A separate control, containing benzoate and butylene oxide, was included to evaluate the toxicity of the test chemical to the inoculum. The presence of the test material did not appear to have a significant effect on the DOC removal capacity of the inoculum indicating no apparent toxicity of the test item. The removal of DOC as butylene oxide was biologically mediated, since DOC removal in the killed (abiotic) controls was <1% at the end of the study (28 d).

Reference 3

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

experimental study

Adequacy of study:

supporting study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

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

GLP compliance:

yes

Oxygen conditions:

aerobic

Inoculum or test system:

mixture of sewage, soil and natural water

Details on inoculum:

concentration 30 mg/L

Duration of test (contact time):

28 d

Initial conc.:

100 mg/L

Based on:

test mat.

Parameter followed for biodegradation estimation:

O2 consumption

Details on study design:

TEST CONDITIONS
- Test temperature: 25 +/- 1°C

Reference substance:

aniline

Parameter:

% degradation (O2 consumption)

Value:

>= 100

Sampling time:

28 d

Details on results:

- At the end of the test 94% recovery of the test substance was determined in the control flask, based on DOC measurement.

Vessel no.	Sample description	BOD (mg)
		7th day	14th day	21st day	28th day
1	Sludge + Aniline	69.1	101.5	111.7	112.1
2	Water + Test substance	0.0	0.0	0.0	0.0
3	Sludge + Test substance	5.4	38.8	68.5	88.9
4	Sludge + Test substance	12.0	39.0	69.6	89.7
5	Sludge + Test substance	12.4	40.6	70.9	91.5
6	Control blank	3.3	6.7	9.4	10.7

	Sludge + Test substance	Sludge + Test substance	Sludge + Test substance	Mean
BOD (%)	107	108	111	109
TOC (%)	79	77	76	77
GC (%)	83	81	80	81

Validity criteria fulfilled:

yes

Interpretation of results:

readily biodegradable

Conclusions:

The test item is readily biodegradable according to OECD criteria

Executive summary:

An experimental study according to OECD guideline 301C and GLP regulations was conducted to assess the biodegradation potential of the test item. A mixture of sewage, soil and water in an initial concentration of 30 mg/L was exposed to the test item with a concnetration of 100 mg/L for 28 d. The biodegradation based on the O2 consumption was measured. After 28 days 109 % of the test item was degraded as mean of three replicates regarding the BOD. The test item can be considered readily biodegradable.

Description of key information

In a CO2-Headspace Test according to ISO 14593 the substance was determined to be readily biodegradable in compliance with OECD criteria (80 - 90 % biodegradation based on CO2 evolution) fulfilling the 10-day-window criterion [BASF AG, 1999].

Key value for chemical safety assessment

Biodegradation in water:

readily biodegradable

Additional information

The ready biodegradability of the test item was investigated in three different screening tests, a headspace test according to ISO 14593 guideline (further on OECD 310), which base on the detection of CO2 evolution [BASF, 2000], a test from the Ministry of International Trade and Industry (MITI I, OECD 301C), which base on the measurement of oxygen consumption [MITI, 1997] and additional a DOC-Die-Away test according to OECD guideline 301 A [Dow, 1999]. As it is required for ready tests the used inoculum was not adapted in all three cases. Since the test item is moderately volatile (Henry’s law = 21.48 Pa.m3/mol) [EPIwin calculation, 2017], closed systems were indicated for testing the biodegradability. The headspace test (ISO 14593) and the MITI I test (OECD 301C) are commonly prepared in closed systems, whereas the DOC-Die-Away test (OECD 301A) is usually prepared in an open test system. In case of testing the test item, the DOC-Die-Away test (OECD 301A) was exceptionally prepared in a closed test system. Therefore, specially designed 1 liter shake flasks were used, which were filled with 500 mL mineral medium and a sufficient amount of test substance. After closing the test flasks the remaining space results into a headspace volume of air. In both studies with closed flasks (ISO 14593 and OECD 301A) abiotic controls were performed to assess volatilization processes. There was no indication of volatilization during the 28 days incubation period.

 

In all three reported guideline studies the pass level for ready biodegradabilityof 1,2-epoxybutane was reached within the required 28 days’ time period. Besides reaching the pass level within 28 days, the ready criteria include the requirement on achievement of the pass level within ten days from the onset of biodegradation. This so-called 10-day-time window requirement applies not to all test systems. MITI I (OECD 301C) is excluded from the ten-day-time window requirement. Hence from the result of the reported MITI I test the test item can be stated as ready biodegradable according to OECD criteria. In the headspace test according to ISO 14593 guideline the detection of the 10-day-time window turned out to be difficult, since the kinetic was recorded in 7 days measuring intervals. From the resulting curves it can be assessed, that the lag phase lasted for about 8 to 10 days and the pass level was reached after approximately 19 to 20 days. Since it was not possible to determine more precise time points, it is not definitely been proved that the 10-day-time window was hold. To take this lack of definition into account, the OECD guidelines permit in case of the Closed Bottle test (OECD 301D), which usually base also on a 7-days measuring interval, to use a 14-days window instead of a 10-day-time window. In the described headspace test the time window is very close to 10 days and a 14-days window was definitely hold. Therefore, in the study report of the headspace test (ISO 14593) of the test item is stated as readily biodegradable. The ready results from the MITI and from the headspace test are complimented by the results of the DOC-Die-Away test. At the end of the DOC-Die-away test the degradation exceed 90%, but missing the 10-day-time window.