2-tetradecyloxirane, reaction products with boric acid

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:

01-10-1997 to 09-06-1998

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study

Remarks:

no information on GLP status, toxicity control not followed

Qualifier:

according to guideline

Guideline:

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

Deviations:

not applicable

Qualifier:

according to guideline

Guideline:

EPA OTS 796.3260 (Ready Biodegradability: Modified Sturm Test)

Deviations:

not applicable

GLP compliance:

not specified

Oxygen conditions:

aerobic

Inoculum or test system:

other: mixture of activated sludge and soil filterate

Details on inoculum:

- Source of inoculum/activated sludge (e.g. location, sampling depth, contamination history, procedure): The inoculum used in this study was composed of six different adaptation cultures. The cultures were maintained concurrently and were prepared as follows: Equal volumes of activated sludge supernatant and soil filtrate were combined and supplemented with 25 mg/L vitamin-free casamino acids and 25 mg/L yeast extract.Soil was collected from a wooded lot adjacent to the Wildlife facility by clearing the soil surface of litter and collecting the exposed soil to a depth of approximately 20 cm. The soil was screened through a sieve with 2 mm openings. Prior to use, approximately 200 g (wet weight) of soil was suspended in 2 L of water. The suspension was allowed to settle for approximately 30 minutes and then the supernatant was filtered through glass wool. The filtrate was aerated until used.Activated sludge was collected from Prospect Bay Wastewater Treatment Facility, Grasonville, Maryland. The sludge was sieved through a 2 mm screen and then aerated for approximately 4 hours. After the aeration period, the sludge was homogenized in a blender at medium speed for approximately 2 minutes. The sludge was allowed to settle for approximately 30 minutes. The supernatant above the settled solids was removed.- Preparation of inoculum for exposure: Approximately 100 mL of supplemented inoculum was combined with approximately 900 mL of test medium within each 2-L Erlenmeyer flask. The solutions were continuously aerated with CO2 free air and the test substances were incrementally added at concentrations equivalent to 4, 8, and 8 mg C/L on days 0, 7 and 11, respectively. On day 14, an equal volume of each culture was combined and the composite inoculum was screened using glass wool and then homogenized in a blender at medium speed for approximately 2 minutes.- Initial cell/biomass concentration: 1.15 x 10^5 CFU/mL (prior to adaptation); 2.47 x 10^5 CFU/mL (after 14-day adaptation)

Duration of test (contact time):

28 d

Initial conc.:

10 other: mg C/L

Based on:

DOC

Parameter followed for biodegradation estimation:

CO2 evolution

Details on study design:

TEST CONDITIONS- Composition of medium: The test medium was a modified biochemical oxygen demand (BOD) test dilution water and was prepared using high quality water. - Test temperature: 18-21 °C- pH: 6.08-6.19TEST SYSTEM- Culturing apparatus: 4 L amber glass vessels- Number of culture flasks/concentration: Triplicate- Method used to create aerobic conditions: All test chambers were aerated with CO2-free air for approximately 24 hours at a rate of 50-100 mL per minute to purge the system of CO2. The air entering the chambers was passed through Drierite to remove ambient moisture and scrubbed using Ascarite to produce CO2-free air.- Measuring equipment: Carbon analyzer- Details of trap for CO2 and volatile organics if used: The air exiting the test chambers was passed through a series of three gas washing bottles each containing approximately 100 mL of 0.5 N KOH to trap the CO2 that had evolved within the chamber. An additional set of gas washing bottles that were not connected to a chamber were maintained concurrently with the traps connected to the chambers. The amount of CO2 detected in these traps was subtracted from the blank control traps to determine the amount of CO2 produced by the blank control.SAMPLING- Sampling frequency: The CO2 traps were removed for analysis on Days 4, 8, 12, 15, 19, 22, 26 and 29.- Sampling method: The CO2 trap nearest the test chamber was removed and analysed for inorganic carbon. The two remaining traps were placed one position closer to the test chamber and a new trap was placed on the end of the series. On the 28th day of the test an aliquot of the contents of each test chamber was removed and the contents of each chamber were then acidified by the addition of 3 mL of concentrated hydrochloric acid to drive off inorganic carbonate. The chambers were aerated overnight and then the trapping solutions closest to the test chambers was analysed for inorganic carbon.CONTROL AND BLANK SYSTEM- Inoculum blank: Yes- Procedure control: Yes- Toxicity control: No

Reference substance:

other: canola oil (10 mg C/L)

Preliminary study:

Not applicable

Test performance:

The viability of the inoculum and validity of the test were supported by the reference substance, canola oil, degrading an average of approximately 88.3%. The amount of CO2 evolved by the control chambers did not exceed the 17 mg/L value considered the acceptable limit for CO2 evolution tests.

Parameter:

% degradation (CO2 evolution)

Value:

26.7

St. dev.:

10.3

Sampling time:

28 d

Details on results:

Average biodegradation after 28 days: 26.7%

Results with reference substance:

Biodegradation of reference substance on Day 29 was 88.3%.

Validity criteria fulfilled:

no

Remarks:

mean % biodegradation of reference substance was > 60% by Day 14; total CO2 evolution in inoculum blank was < 17 mg/L; difference between replicate values at end of test > 20%; toxicity control not followed

Interpretation of results:

not readily biodegradable

Conclusions:

The test substance was determined to be not readily biodegradable under the conditions of the study.

Executive summary:

Test Guidelines

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

EPA OTS 796.3260 (Ready Biodegradability: Modified Sturm Test)

ASTM Standard Test Method D 5864-95

 

Method and materials

In the CO2 test, inoculated test medium is dosed with a known amount of test substance as the nominal sole source of organic carbon and aerated with CO2-free air. The CO2 produced from the mineralization of organic carbon within the test chambers was displaced by the flow of CO2 -free air and trapped as K2CO3 in KOH trapping solution. The amount of CO2 produced from the biodegradation of the test substance (corrected for that evolved by the blank inoculum) was expressed as a percentage of the theoretical amount of CO2 (TCO2). The test contained an inoculum control group, a reference group and a treatment group. Each group contained triplicate test chambers. The control group was used to measure the background CO2 production of the inoculum and was not dosed with a carbon source. The reference group was dosed with canola oil, a substance known to be biodegradable, at a nominal concentration of 10 mg C/L. The treatment group test chambers were used to evaluate the test substance at a nominal concentration of 10 mg C/L.

Results

The viability of the inoculum and validity of the test were supported by the reference substance, canola oil, degrading an average of approximately 88.3%. The amount of CO2 evolved by the control chambers did not exceed the 17 mg/L value considered the acceptable limit for CO2 evolution tests. The results for the test substance were an average of 26.7% degradation over a 28-day test period.

Conclusion

The test substance was determined to be not readily biodegradable under the conditions of the study.

Key value for chemical safety assessment

Biodegradation in water:

not biodegradable

Type of water:

freshwater