Amides, adipic 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:

27 May 2019 to 19 July 2019

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 310 (Ready Biodegradability - CO2 in Sealed Vessels (Headspace Test)

GLP compliance:

yes

Oxygen conditions:

aerobic

Inoculum or test system:

sewage, predominantly domestic (adaptation not specified)

Details on inoculum:

For the preparation of the inoculum a sample of aerobic sludge has been selected by the mixed treatment plant of urban (about 66%) and industrial (about 34%) liquid sewage situated at San Rocco-Monza (MB), Italia. . Then it has been centrifuged, washed and analyzed to quantify the suspended solids concentration for the inoculum preparation. The inoculum was prepared in order to have a concentration of suspended solid of about 4 mg/L.

Duration of test (contact time):

ca. 28 d

Initial conc.:

16.75 mg/L

Based on:

TOC

Parameter followed for biodegradation estimation:

CO2 evolution

Details on study design:

ASSAY EXECUTION:
For assay execution the following preparations have been done using deionised water. Bottles not used have been eliminated at the end of the test.
Test sample:
The elemental analysis of the test substance has been determined by REDOX SnC using CHN analyser. The sample has been used with the starting nominal concentration of 16.75 mg/L of organic carbon (TOC).
Reference substance:
Considering Sodium benzoate as reference substance using its molecular formula, a starting nominal concentration of 17.28 mg/L of organic carbon (TOC) has been used.
Blank:
As blank has been used water containing culture Medium added with the inoculum of the muds.
Test sample + Reference substance:
Test sample and reference substance have been put together in order to have final concentration given by the sum of organic carbon (TOC) of the 2 substances (see attachment N. 3 for results).
Abiotic check:
Test substance has been put together with 50 mg/L HgCl, in order to check a possible abiotic degradation.

Conditions of assay:
The inoculum has been added in all bottles (see bottle preparation), closed and incubation continued under stirring in darkness at 20±
1 °C for 28days. Data recording is performed continuously by a validated informatic monitoring system (Labguard Evisense). At least 1 hour before every determination of inorganic carbon (TIC) the reaction in one bottle of blank, one of reference substance and one of the test substances has been stopped with the addition of 6 mL of sodium hydroxide (1 M). Triplicate bottles have been analyzed to detection inorganic carbon (IC) at each check point, weekly, except at the end of the test where five bottles have been analyzed
Determination of total organic carbon (TOC) and total inorganic carbon (TIC)
Determination of total inorganic carbon has been done using an automatic TOC analyser. It is a high sensitivity instrument based on the combustion catalytic oxidation method (680°C). The carbon dioxide generated by oxidation has been detected using an infrared gas analyzer (NDIR). Samples, properly diluted with deionised water with low TOC contents, have been analysed by means of an integrated sampling system directly from vials containing 40 mL volume.

Reference substance:

benzoic acid, sodium salt

Remarks:

Batch No. SLBW2610

Key result

Parameter:

% degradation (CO2 evolution)

Value:

81

Sampling time:

28 d

Remarks on result:

other: readily biodegradable in aerobic conditions

Details on results:

The percentage biodegradation of the test substance reached a mean of 81% after 28 d based on the TOC of the test substance. Abiotic degradation has not occurred because amount of TIC during the test in the abiotic bottles has been lower than 10%. Therefore the test substance is considered readily biodegradable.

Validity criteria fulfilled:

yes

Interpretation of results:

readily biodegradable

Conclusions:

Under the test conditions, the test substance was considered to be readily biodegradable.

Executive summary:

A study was conducted to determine the ready biodegradability of the test substance according to OECD Guideline 310, in compliance with GLP. The test substance at an initial concentration of 16.75 mg/L was exposed to sewage sludge for 28 d. Biodegradation by the microorganisms of the sludge was measured by the amount of CO2 produced during exposure. As a reference substance, sodium benzoate (at 17.28 mg/L) was tested simultaneously under the same conditions. Additionally, inoculum controls and test substance has been put together with 50 mg/L HgCl, in order to check possible abioticdegradation[FT1] . Sodium benzoate was degraded up to 106% after 28 d based on total organic carbon, thus confirming the suitability of the inoculum. In the mixture containing both the test substance and sodium benzoate, a mean of 99% biodegradation was observed in 28 d of incubation. Under the test conditions, the test substance was considered to be readily biodegradable (Giarei, 2019).

Key value for chemical safety assessment

Biodegradation in water:

readily biodegradable

Type of water:

freshwater

Additional information

A study was conducted to determine the ready biodegradability of the test substance according to OECD Guideline 310, in compliance with GLP. The test substance at an initial concentration of 16.75 mg/L was exposed to sewage sludge for 28 d. Biodegradation by the microorganisms of the sludge was measured by the amount of CO2 produced during exposure. As a reference substance, sodium benzoate (at 17.28 mg/L) was tested simultaneously under the same conditions. Additionally, inoculum controls and test substance has been put together with 50 mg/L HgCl, in order to check possible abioticdegradation[FT1] . Sodium benzoate was degraded up to 106% after 28 d based on total organic carbon, thus confirming the suitability of the inoculum. In the mixture containing both the test substance and sodium benzoate, a mean of 99% biodegradation was observed in 28 d of incubation. Under the test conditions, the test substance was considered to be readily biodegradable (Giarei, 2019).