Reaction mass of bisisopropyl peroxydicarbonate and bis-sec-butyl peroxydicarbonate and isopropyl-secbutylperoxydicarbonate

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:

Experimental starting date 11-12-2013 Experimental completion date 09-01-2014

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 301 D (Ready Biodegradability: Closed Bottle Test)

Qualifier:

according to guideline

Guideline:

EU Method C.4-E (Determination of the "Ready" Biodegradability - Closed Bottle Test)

Qualifier:

according to guideline

Guideline:

ISO 10707 Water quality - Evaluation in an aqueous medium of the "ultimate" aerobic biodegradability of organic compounds - Method by analysis of biochemical oxygen demand (closed bottle test)

GLP compliance:

yes (incl. QA statement)

Specific details on test material used for the study:

Name (active material) mixture of peroxydicarbonates
Trade name Trigonox ADC NS30
Batch/lot No.: 13031B1705
Solubility in water: insoluble
Stability: not relevant
Storage: <-10°C in the dark

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, domestic, non-adapted

Details on inoculum:

Secondary activated sludge (05-12-2013) was obtained from the wastewater treatment plant Nieuwgraaf in Duiven, The Netherlands. This plant is an activated sludge plant treating predominantly domestic wastewater. The activated sludge was preconditioned to reduce the endogenous respiration rates. To this end, 400 mg Dry Weight (DW)/L of activated sludge was aerated for one week. The sludge was diluted in the BOD bottles to 2.0 mg/L (van Ginkel and Stroo, 1992).

Duration of test (contact time):

28 d

Initial conc.:

4 mg/L

Based on:

test mat.

Parameter followed for biodegradation estimation:

O2 consumption

Details on study design:

Deionized water
Deionized water containing no more than 0.01 mg/L Cu (Sterlab certified; non-GLP analysis) was prepared in a water purification system.

Test bottles
The test was performed in 0.30 L BOD (biological oxygen demand) bottles with glass stoppers.

Nutrients, stocks and administration
The nutrient medium of the Closed Bottle test contained per liter of deionized water; 8.5 mg KH2PO4, 21.75 mg K2HPO4, 33.3 mg Na2HPO4·2H2O, 22.5 mg MgSO4·7H2O, 27.5 mg CaCl2, 0.25 mg FeCl3·6H2O. Ammonium chloride was omitted from the medium to prevent nitrification. Accurate administration of the test substance and diethylene glycol bis(allylcarbonate) was accomplished with solid stocks of 6.0, and 4.2 mg substance/g silica gel. Subsequently 0.2 g of silica gel dosed with these substances was added to the respective test bottles. Next the bottles were filled with nutrient medium with inoculum and closed. The control bottles contained 0.2 g silica gel. Sodium acetate was added to the bottles using a stock solution of 1.0 g/L in water.

Test procedures
The Closed Bottle test was performed according to the study plan. The study plan was developed from ISO Test Guidelines (1994). Use was made of 10 bottles containing only inoculum, 10 bottles containing silica gel and inoculum, 10 bottles containing inoculums, silica gel, and test substance, 10 bottles containing inoculums, silica gel and diethylene glycol bis(allylcarbonate), and 6 bottles containing sodium acetate and inoculum. The concentrations of the test substance, diethylene glycol bis(allylcarbonate) and sodium acetate in the bottles were 4.0, 2.8, and 6.7 mg/L, respectively. Each of the prepared solutions was dispensed into the respective group of BOD bottles so that all bottles were completely filled without air bubbles. The zero time bottles were immediately analyzed for dissolved oxygen using an oxygen electrode. The remaining bottles were closed and incubated in the dark. Two duplicate bottles of all series were withdrawn for analyses of the dissolved oxygen concentration at day 7, 14, 21, and 28.

Calculation of the results
Calculation of endogenous respiration
The endogenous respiration (oxygen depletion in the control) was calculated as follows;
Oxygen depletion (endogenous respiration) (mg/L) = Mc (day 0) - Mc (day 28)
Mc is the mean oxygen level in the control bottles.

Calculation of the theoretical oxygen demand (ThOD)
The ThODs of the active substance (isopropyl-sec-butylperoxydicarbonate, bis-sec-butyl peroxydicarbonate, diisopropyl peroxy dicarbonate), diethylene glycol bis(allylcarbonate), and sodium acetate were calculated from their molecular formulae and molecular weights as follows.

ThOD_NH3 (mg O2/mg) = (16(2C+0.5(H-Cl-3N)+3S+2.5P+0.5Na-O))/MW

Calculation of the biochemical oxygen demand (BOD)
Provided that the oxygen concentrations in all bottles at the start of the test were equal, the amounts of oxygen consumed in test and reference compound bottles were calculated as follows:
Oxygen consumption (mg/L) by test substance = Mcs - Mt
Oxygen consumption (mg/L) by diethylene glycol bis(allylcarbonate) = Mcs - Mdb
Oxygen consumption (mg/L) by reference compound = Mc - Ma
Mc or cs is the mean oxygen level in the control bottles (c) and control bottles with silica gel (cs) n-days after the start of the test.
Mt or db or a is the mean oxygen concentration in the bottles containing the test substance (t) or diethylene glycol bis(allylcarbonate) (db) the reference compound, sodium acetate (a), n-days after the start of the test.
The biological oxygen demand (BOD) mg/mg of the test substance, diethylene glycol bis(allylcarbonate) and sodium acetate was calculated by dividing the oxygen consumption by the concentration of the test substance and sodium acetate in the closed bottle, respectively.

Calculation of the biodegradation percentages
The biodegradation was calculated as the ratio of the biochemical oxygen demand (BOD) to the theoretical oxygen demand (ThOD).

Reference substance:

acetic acid, sodium salt

Test performance:

Test conditions
The pH of the media was 7.3 at the start of the test. The pH of the medium at day 28 was 7.3 (controls) and 7.2 (test and diethylene glycol bis(allylcarbonate)). Temperatures were within the prescribed temperature range of 22 to 24°C.

Parameter:

% degradation (O2 consumption)

Value:

73

Sampling time:

28 d

Remarks on result:

other: test substance

Parameter:

% degradation (O2 consumption)

Value:

71

Sampling time:

28 d

Remarks on result:

other: active material

Details on results:

The biodegradability of test substance containing 28% of mixture of peroxydicarbonates (active) is biodegraded by 73% at day 28 in the Closed Bottle test. The biodegradability of diethylene glycol bis(allylcarbonate) was determined to enable calculation of biodegradation percentages for the active substance. A biodegradation percentage of 74 at day 28 was found with diethylene glycol bis(allylcarbonate). The biodegradability of the active substance mixture of peroxydicarbonates was calculated by subtracting the oxygen consumption caused by diethylene glycol bis(allylcarbonate) from the oxygen consumption due to degradation of the test substance. This gives an oxygen consumption of 1.2 mg/L for the active substance at day 28. The biodegradability is calculated by dividing the oxygen consumption by the ThOD of the active in the bottles i.e. 1.7 mg/L. This results in a biodegradation percentage of 71 at day 28 of the active substance. This biodegradation percentage cannot be very accurate due to the low content of the active material in the test substance. This result does, however, clearly indicate that the active is readily biodegradable.
The pass level of 60% was not reached within 14 days upon achieving 10% biodegradation. The test substance does therefore not meet the time window criterion. The test substance is a mixture of two chemicals. The biodegradation kinetics of the individual compounds in a mixture is not necessarily the same. The biodegradation of a mixture consisting of three organic compounds is an addition of different biodegradation curves. It is thus possible that the individual compounds meet the time window criterion whereas the biodegradability curve of the mixture suggests that the test substance is not readily biodegradable (Battersby, 2000; Richterich and Steber, 2001).
Mixture of peroxydicarbonates (test substance) is therefore classified as readily biodegradable based on the biodegradation percentages of 73 (test substance) and 71 (active material) at day 28.

Toxicity
Inhibition of the degradation of a well-degradable compound, e.g. sodium acetate by the test substance in the Closed Bottle test was not determined because
possible toxicity of the test substance to microorganisms degrading acetate is not relevant. Inhibition of the endogenous respiration of the inoculum by the test
substance at day 7 was not detected. Therefore, no inhibition of the biodegradation due to the "high" initial test substance concentration is expected.

Parameter:

ThOD

Value:

1.5 other: mg O2/mg test mat.

Results with reference substance:

The biodegradation percentage of the reference compound, sodium acetate, at day 14 was 90.

Theoretical oxygen demand (ThOD)

The calculated theoretical oxygen demand (ThOD) of diethylene glycol bis(allylcarbonate) is 1.52 mg/mg. The ThOD of the active material (isopropylsec-butylperoxydicarbonate, bis-sec-butyl peroxydicarbonate, diisopropyl peroxy dicarbonate) is 1.45 mg/mg. The ThOD of test substance (mixture of peroxydicarbonates) containing 28% of active material and 72% of diethylene

glycol bis(allylcarbonate) is 1.50 mg/mg. The ThOD of sodium acetate is 0.78 mg/mg.

Dissolved oxygen concentrations (mg/L) in the closed bottles.

 

Time (days)	Oxygen concentration (mg/L)
	Ocs	Ot	Odb	Oc	Oa
0	8.9	8.9	8.9	8.9	8.9
	8.9	8.9	8.9	8.9	8.9
Mean (M)	8.9	8.9	8.9	8.9	8.9
7	8.7	7.3	8.3	8.5	4.1
	8.7	7.6	8.4	8.6	4.1
Mean (M)	8.7	7.5	8.4	8.6	4.1
14	8.4	5.9	6.5	8.5	3.7
	8.4	5.5	6.6	8.5	3.8
Mean (M)	8.4	5.7	6.6	8.5	3.8
21	8.2	5.0	6.1	8.4
	8.3	4.7	5.9	8.4
Mean (M)	8.3	4.9	6.0	8.4
28	8.2	3.6	5.0	8.2
	8.2	4.0	4.9	8.3
Mean (M)	8.2	3.8	5.0	8.3

O_csMineral nutrient solution with only inoculum and silica gel.

O_tMineral nutrient solution with test material (4.0 mg/L), and inoculum.

O_dbMineral nutrient solution with diethylene glycol bis(allylcarbonate) (2.8 mg/L), and inoculum.

O_cMineral nutrient solution with only inoculum.

O_aMineral nutrient solution with sodium acetate (6.7 mg/L) and with inoculum.

Oxygen consumption (mg/L) and the percentages biodegradation (BOD/ThOD) of the test substance, the active material, diethylene glycol bis(allylcarbonate) and sodium acetate in the Closed Bottle test. The oxygen consumption by the active material was calculated by subtracting the oxygen consumption by diethylene glycol bis(allylcarbonate) (RAV 750) from the consumption by the test substance.

 

Time (day)	Oxygen consumption (mg/L)				Biodegradation (%)
	Test substance	RAV 750	Active	Acetate	Test substance	RAV 750	Active	Acetate
0	0.0	0.0	0.0	0.0	0	0	0	0
7	1.2	0.3	0.9	4.5	20	7	53	87
14	2.7	1.8	0.9	4.7	45	42	53	90
21	3.4	2.3	1.1		57	53	65
28	4.4	3.2	1.2		73	74	71

Validity criteria fulfilled:

yes

Interpretation of results:

readily biodegradable

Conclusions:

The presence of mixture of peroxydicarbonates (test substance) did not cause a reduction in the endogenous respiration. The test substance is therefore considered to be non-inhibitory to the inoculum.
Mixture of peroxydicarbonates was biodegraded by 73% at day 28 in the Closed Bottle test. A biodegradation percentage of 71 at day 28 was calculated for the active material. Mixture of peroxydicarbonates is therefore classified as readily biodegradable.
The test is valid as shown by an endogenous respiration of 0.6 mg/L and by the total mineralization of the reference compound, sodium acetate. Sodium acetate was degraded by 90% of its theoretical oxygen demand after 14 days. Finally, the most important criterion was met by oxygen concentrations >0.5 mg/L in all bottles during the test period.

Executive summary:

In order to assess the biotic degradation, a ready biodegradability test was performed which allows the biodegradability to be measured in an aerobic aqueous medium. The ready biodegradability was determined in the Closed Bottle test performed according to slightly modified OECD, EU and ISO Test Guidelines, and in compliance with the OECD principles of Good Laboratory Practice.

The presence of mixture of peroxydicarbonates (test substance) did not cause a reduction in the endogenous respiration. The test substance is therefore considered to be non-inhibitory to the inoculum.

Mixture of peroxydicarbonates was biodegraded by 73% at day 28 in the Closed Bottle test. A biodegradation percentage of 71 at day 28 was calculated for the active material. Mixture of peroxydicarbonates is therefore classified as readily biodegradable.

The test is valid as shown by an endogenous respiration of 0.6 mg/L and by the total mineralization of the reference compound, sodium acetate. Sodium acetate was degraded by 90% of its theoretical oxygen demand after 14 days. Finally, the most important criterion was met by oxygen concentrations >0.5 mg/L in all bottles during the test period.

Description of key information

Mixture of peroxydicarbonates was biodegraded by 73% at day 28 in the Closed Bottle test. A biodegradation percentage of 71 at day 28 was calculated for the active material. Mixture of peroxydicarbonates is therefore classified as readily biodegradable.

Key value for chemical safety assessment

Biodegradation in water:

readily biodegradable