Dibutyl peroxydicarbonate

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:

2017-09-22 to 2018-05-09

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

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

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, domestic, non-adapted

Details on inoculum:

Activated sludge from the municipal wastewater treatment plant AZV Staufener Bucht was used as inoculum with a concentration corresponding to 30 mg dry solids per litre. The treatment plant clarifies predominantly domestic wastewater and has a capacity of 140,000 inhabitant equivalents. Sampling date of activated sludge was on 4 October 2017. The dry solid content of the activated sludge was 4.5 g/L. lt was determined by weight measurements after drying at 105 °C for 5 hours (mean of triplicate measurements). The activated sludge was washed one time with tap water and one time with mineral medium by settling the sludge, decanting the supernatant and re-suspending the sludge.

Duration of test (contact time):

28 d

Initial conc.:

20 mg/L

Based on:

TOC

Parameter followed for biodegradation estimation:

CO2 evolution

Details on study design:

A solution of the test item in a mineral medium, corresponding to 20 mg TOC/L, is inoculated with activated sludge (30 mg d. s./L). The test vessels are aerated by the passage of carbon dioxide-free air and are incubated under aerobic conditions in diffuse light for 28 days. Degradation is followed by determining the carbon dioxide produced and absorbed to sodium hydroxide via lC-measurement (lC= inorganic carbon).

TEST CONDITIONS
- Composition of medium: refer to "Any other information on material and methods incl. tables" below
- Test temperature: 21.2 - 24.0 °C
- pH: 7.4
- pH adjusted: no

CONTROL AND BLANK SYSTEM
In total three reactors containing the test item, three reactors containing only inoculum (blank), three reactors containing the reference compound and one reactor containing test item and reference compound (toxicity control) were set up.

Reference substance:

benzoic acid, sodium salt

Parameter:

% degradation (CO2 evolution)

Value:

18.97

Sampling time:

28 d

Details on results:

The degradation of the toxicity control after 14 days was 58.7%. Therefore, the test item had no inhibitory effect on the inoculum according to the criterion of the guideline.

Table 1: Ultimate biodegradation after x days [% of ThCO2]

Reactor	Day	0	4	7	11	14	21	28	29
7	Test flasks	0	23.2	31	38.5	37.4	37.1	31.2	30.5
8		0	17.2	26.7	29.1	25.6	20.8	12.8	13.2
9		0	14.4	24	29.1	25	23	12.6	13.2
4	reference flasks	0	60.8	74.8	80.6	81.9	79.6	82.2	79.9
5		0	72.7	82	82.3	88.4	91.8	92.5	92.5
6		0	67.4	81.6	84.1	86.3	86.2	92.6	90.9
10	Toxicity control	0	43.3	54.1	57.9	58.7	54.5	51.1	51.5
11	abiotic control	0	4	7.1	7.8	9.5	13.4	16.4	38.6

Table 2: Mean CO2-evolution of blank flasks after x days

Day	0	4	7	11	14	21	28	29
CO2-evolution [mg/l]	0	10.4	15.5	22.3	25.8	39.3	51.9	52.7

Validity criteria fulfilled:

yes

Interpretation of results:

not readily biodegradable

Conclusions:

The degradation percentage of the test item at the end of the test showed values between 13.2 and 30.5 %. The mean degradation extent on day 28 of the three replicates was app. 19.0 %.
Under the experimental conditions, dibutyl peroxydicarbonate was therefore not readily biodegradable (60 % of ThCO2 within a 10-d window) in the 28-day modified Sturm test.

Executive summary:

The ready biodegradability of dibutyl peroxydicarbonate (containing isododecane as stabiliser) was evaluated in a 28-day modified Sturm test according to the OECD guideline 301 B at an initial test substance concentration of 20 mg/L TOC.

The degradation percentage of the test item at the end of the test showed values between 13.2 and 30.5 %. The mean degradation extent on day 28 of the three replicates was 19.0 %. Under the conditions of the CO₂ evolution test, the test item dibutyl peroxydicarbonat is not readily biodegradable.

Description of key information

The test item dibutyl peroxydicarbonat is not readily biodegradable under the conditions of the CO₂ evolution test according to OECD 301B.

Key value for chemical safety assessment

Biodegradation in water:

under test conditions no biodegradation observed

Type of water:

freshwater