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Environmental fate & pathways

Biodegradation in water: screening tests

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Reference
Endpoint:
biodegradation in water: ready biodegradability
Type of information:
migrated information: read-across based on grouping of substances (category approach)
Adequacy of study:
key study
Study period:
2010-03-05 to 2010-04-09
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: This is a GLP guideline study and is used in read-across from Alchisor CAL 123 (see 'Read Across Justification Document'). The study merits a Klimisch 1 rating; Klimisch 2 when used for read-across.
Qualifier:
according to
Guideline:
OECD Guideline 301 B (Ready Biodegradability: CO2 Evolution Test)
Deviations:
no
Qualifier:
according to
Guideline:
EU Method C.4-C (Determination of the "Ready" Biodegradability - Carbon Dioxide Evolution Test)
Deviations:
no
GLP compliance:
yes
Oxygen conditions:
aerobic
Inoculum or test system:
sewage, predominantly domestic, non-adapted
Details on inoculum:
- Source of inoculum/activated sludge: collected from Cambridge Wastewater Treatment Facility, Cambridge, Maryland, USA
- Laboratory culture: no
- Storage conditions: aerated at test temperature until use
- Storage length: no data
- Preparation of inoculum for exposure: the sludge was sieved using a 2-mm screen, adjusted to approx. 1000 mg total suspended solids (TSS)/L with mineral media
- Pretreatment: none
- Concentration of sludge: 940 mg TSS/L
- Initial cell/biomass concentration: 9.3 x 10 E4 CFU/mL (colony forming units/mL)
Duration of test (contact time):
28 d
Initial conc.:
10 mg/L
Based on:
other: measured carbon content
Parameter followed for biodegradation estimation:
CO2 evolution
Details on study design:
TEST CONDITIONS
- Composition of medium: 1 mL calcium chloride solution (2.75%), 1 mL ferric chloride solution (0.025%), 1 mL magnesium sulphate solution (2.25%), 10 mL phosphate buffer (pH 7.4) per L of high quality water (NANOpure)
- Additional substrate: none
- Solubilising agent (type and concentration if used): not used
- Test temperature: 20 +/- 2 °C
- pH: 7.4 - 7.5
- pH adjusted: no
- CEC (meq/100 g): no data
- Aeration of dilution water: no data
- Suspended solids concentration: approx. 30 mg/L final TSS concentration in the test chambers
- Continuous darkness: yes

TEST SYSTEM
- Culturing apparatus: amber 4-liter bottles connected with 3 CO2 traps, each containing 100 mL 0.5 N KOH in a serial order
- Number of culture flasks/concentration: 3
- Method used to create aerobic conditions: aerated with CO2 free air at a rate of 50 to 100 mL per minute
- Measuring equipment: Shimadzu Model TOC-Vcsh carbon analyzer
- Test performed in closed vessels due to significant volatility of test substance: no
- Test performed in open system: yes
- Details of trap for CO2: no data

SAMPLING
- Sampling frequency: on days 1, 4, 7, 11, 15, 18, 21, 25, 28 and 29 (after acidification)
- Sampling method: The CO2 trap nearest the test chamber was removed and analyzed 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, the contents of all chambers were acidified (addition of 3 mL of concentrated hydrochloric acid) to drive off inorganic carbonate. All chambers were aerated overnight and then a sample of each test chamber was removed for dissolved organic carbon analysis and the trapping solution closest to the test chambers were removed for inorganic carbon analysis.
- Sterility check if applicable: not made
- Sample storage before analysis: not mentioned

CONTROL AND BLANK SYSTEM
- Inoculum blank: yes
- Abiotic sterile control: no
- Toxicity control: no

STATISTICAL METHODS: no statistics performed
Reference substance:
benzoic acid, sodium salt
Remarks:
10 mg C/L
Test performance:
The test substance was administered by direct weight addition. The amount of test substance used was calculated based on the measured carbon content. The biodegradation test was started by bubbling CO2-free air through each of the test chambers at a rate of 50 - 100 mL per minute. Magnetic stir bars and stir plates were used to mix the content of the tes chambers. The CO2 produced from the degradation of organic carbon sources within the test chamber was trapped as K2CO3 in the KOH solution and the amount of inorganic carbon in the trapping solution was measured at the above mentioned days during the study, using a Shimadzu carbon analyzer.
Parameter:
% degradation (CO2 evolution)
Value:
ca. 87.7
Sampling time:
28 d
Details on results:
see table below
Results with reference substance:
The viability of the inoculum and validity of the test were supported by the results of the reference substance from which an average of 90.8 % of theoretical CO2 was evolved. An average percent biodegradation of greater than 60% was achieved by day 7, thereby fulfilling the criteria for a valid test by reaching the pass level by day 14.
Table: Cumulative Percent of Theoretical Carbon Dioxide Evolved:
Day Reference substance Test substance
  mean Rep. 1 Rep. 2 Rep. 3 mean
1 4.1 -0.6 -0.9 -0.7 -0.7
4 42.7 7.1 5.6 1.8 4.8
7 61.1 21.2 16.4 14.1 17.2
11 73.5 39.4 30.7 31.5 33.9
15 80.9 53.7 46.2 47.8 49.2
18 84.2 61.6 56.4 56.5 58.2
21 86.1 67.1 63.2 62 64.1
25 88.3 72.1 69.5 67 69.5
28 (after acidification) 90.8 89.4 89 84.7 87.7
Validity criteria fulfilled:
yes
Interpretation of results:
readily biodegradable, but failing 10-day window
Conclusions:
The final mean percent biodegradation for Alkenes, C11-12 hydroformylation products, distn. residues was 87.7 % over a 28-day test period. Alkenes, C11-12 hydroformylation products, distn. residues was not considered readily biodegradable, since the pass level of 60 % TCO2 was not achieved with 10 days of reaching 10 % TCO2.
Executive summary:

The ready biodegradability of Alkenes, C11-12 hydroformylation products, distn. residues was determined by the Carbon Dioxide Evolution Test Method (OECD Guideline 301B). Inoculated mineral medium was dosed with a known amount of test substance as the nominal sole source of organic carbon and aeraed 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 by the test substance (corrected for that evolved by the blank inoculum) was expressed as a percentage of the theoretical amount of CO2 (TCO2) that could have been produced if complete biodegradation of the test substance occurred. The test contained a blank control group, a reference group and a treatment group. Each group contained three replicate test chambers. The blank control was used to measure the background CO2 production of the inoculum and was not dosed with a carbon source. The reference chambers were dosed with sodium benzoate, 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. The results indicated that the activated sludge inoculum was active, degrading the reference substance 90.8 %. The average cumulative percent biodegradation for Alkenes, C11-12 hydroformylation products, distn. residues was 87.7 % after 28 days and not considered readily biodegradable, since the OECD critera for ready biodegradability (60% of TCO2 within a 10 -day window of reaching 10% TCO2) was not reached..

Description of key information

Alchisor CAL 145 (based on read-across from Alchisor CAL 123) was assessed for ready biodegradability in a reliable (Klimisch 1; Klimisch 2 when used for read-across), GLP compliant OECD Guideline 301B (Ready Biodegradability: CO2 Evolution Test). On the basis of this study Alchisor CAL 123 can be regarded as readily biodegradable

Key value for chemical safety assessment

Biodegradation in water:
readily biodegradable

Additional information

Alchisor CAL 145 comprises alkenes C13-14 hydroformylation products with read-across from the chemically-similar Alchisor CAL 123 as defined in the `Read-Across Justification Document'. Where environmental fate data exist for Alchisor CAL 123, these are representative of the Alchisor CAL 145 substance.

Alchisor CAL 123 was assessed for ready biodegradability in a reliable (Klimisch 1; Klimisch 2 when used for read-across), GLP compliant OECD Guideline 301B (Ready Biodegradability: CO2 Evolution Test). The test substance biodegraded to an extent of 87.7% after 28 days with an unacclimated sewage sludge inoculum. The test substance did not achieve 60% degradation with a 10-day window for ready biodegradability; Alkenes. As Alkenes, C11-12, hydroformylation products, distn. Residues are a mixture, the 10-day window test is not applicable as the only determination of ready biodegradability as different components of the mixture can degrade preferentially (reference TG 103C). On the basis of this study Alchisor CAL 123 can be regarded as readily biodegradable.

 

Since this UVCB is a mixture of esters, ethers, paraffins, aldehydes and alcohols it is unlikely that any of these components would be degraded into chemicals that might be of cause for concern.