Hydroxyacetone

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:

2018/01/10-2018/02/07

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 301 F (Ready Biodegradability: Manometric Respirometry Test)

Deviations:

no

Qualifier:

according to guideline

Guideline:

EU Method C.4-D (Determination of the "Ready" Biodegradability - Manometric Respirometry Test)

GLP compliance:

yes (incl. QA statement)

Remarks:

Landesamt für Umwelt, 55116 Mainz (15.05.2018)

Specific details on test material used for the study:

The test item was stored in a tightly closed vessel at room temperature (20 ± 5°C).

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, domestic, non-adapted

Details on inoculum:

- Source of inoculum/activated sludge (e.g. location, sampling depth, contamination history, procedure): The sludge was taken from the activation basin of the ESN (Stadtentsorgung Neustadt) sewage treatment plant, Im Altenschemel, NW-Lachen-Speyerdorf. Date of collection: 10. Jan. 2018, batch no: 20180110.
- Method of cultivation: The sludge was filtrated, washed with test medium 2x, and resuspended in test medium. It was then aerated. The dry matter was determined as 5000 mg suspended solids/L.

Duration of test (contact time):

28 d

Initial conc.:

66 mg/L

Based on:

test mat.

Remarks:

corresponding to a ThOD of 100.4 mg/L

Parameter followed for biodegradation estimation:

O2 consumption

Details on study design:

TEST CONDITIONS
- Composition of medium:
The medium was freshly prepared (volumes were adapted to final volume needed in the test).
Composition:
Solution a 10 mL
Solution b 1 mL
Solution c 1 mL
Solution d 1 mL
H2O demin. ad 1000 mL

Solution a
Potassium dihydrogen phosphate (KH2PO4): 8.5 g
Dipotassium hydrogen phosphate (K2HPO4): 21.75 g
Disodium hydrogenphosphate dihydrate (Na2HPO4*2H2O): 33.4 g
Ammonium chloride (NH4Cl): 0.5 g
H2O demin. ad 1000 mL
The pH was 7.4.

Solution b
Calcium chloride (CaCl2) 27.5 g
H2O demin. ad 1000 mL

Solution c
Magnesium sulphate heptahydrate (MgSO4*7H2O) 22.5 g
H2O demin. ad 1000 mL

Solution d
Iron(III) chloride hexahydrate (FeCl3*6H2O) 0.25 g
Disodium ethylene-diaminetetraacetate dihydrate (Na2EDTA*2H2O) 0.4 g
H2O demin. ad 1000 mL

- Test temperature: 20.7-20.9 °C
- pH: 7.3-7.6
- pH adjusted: yes (7.4 - 7.6)
- Suspended solids concentration: dry matter was determined as 5000 mg suspended solids/L.

TEST SYSTEM
- Culturing apparatus: 500 mL-flasks were used as test vessels.
- Number of culture flasks/concentration: 3
- Measuring equipment: OxiTop®-C measuring heads
- Details of trap for CO2 and volatile organics if used: Evolved carbon dioxide is absorbed in soda lime (mixture of sodium hydroxide and calcium hydroxide). The soda lime is filled in the OxiTop®-C measuring heads

SAMPLING
- Sampling method:The oxygen which was consumed by the content of the vessels was measured automatically by the test apparatus.


CONTROL AND BLANK SYSTEM
- Inoculum blank: 3 test vessels (medium and inoculum)
- Abiotic sterile control: 1 test vessels (test item and 10 mL 1% HgCl2 solution/L)
- Toxicity control: 1 test vessels (199.11 mg/L ThOD, ThOD test item and ThOD positive control)

Reference substance:

benzoic acid, sodium salt

Remarks:

60 mg/L sodium benzoate (corresponding to a ThOD of 99.93 mg/L)

Test performance:

The oxygen which was consumed by the content of the vessels was measured automatically by the test apparatus.
After 28 days, the test was ended.
Because the test item and positive control do not contain nitrogen, presence of nitrate and nitrite was not checked.

Parameter:

% degradation (O2 consumption)

Value:

82

Sampling time:

28 d

Key result

Parameter:

% degradation (O2 consumption)

Value:

73

Sampling time:

10 d

Remarks on result:

other: from day 2 to day 12

Details on results:

The degree of biodegradation reached 82 % after 28 days for the test item. The degradation phase was from day 2 to day 12.
The 10-day-window began on day 2. At its end (day 12), 73 % biodegradation was reached (this is stated as lag phase), staying above the pass level of 60 % given in the OECD guideline.

Results with reference substance:

The positive control reached the pass level of 60% on day 4 (criterion: <= 14 days)

table 2a: pH value on day 0 and day 28 and Oxygen demand and degradation values on day 28

Flask	Blank control 1	Blank control 2	Blank control 3	Positive control 1	Positive control 2	Positive control 3
pH at day 0	7.6	7.6	7.6	7.6	7.6	7.6
pH at day 28	7.4	7.4	7.4	7.6	7.6	7.6
Oxygen demand in mg/L at day 28	19.8*	21.5*	21.5*	108	110	104
Oxygen demand in mg/L after deductions	--	--	--	87.1	89.1	83.1
% biological degradation	--	--	--	87.1	89.1	83.1

*mean = 20.9 mg/L

table 2b: pH values on day 0 and day 28 and Oxygen demand and degradation values on day 28 (continued)

Flask	Test item1	Test item2	Test item3	Mean Test item	Abiotic Control	Toxicity Control
pH at day 0	7.6	7.6	7.6	--	7.4	7.4
pH at day 28	7.4	7.4	7.4	--	7.3	7.5
Oxygen demand in mg/L at day 28	102	106	101	--	1.8	184
Oxygen demand in mg/L after deductions	81.1	85.1	80.1	--	1.8	163.1
% biological degradation	80.7	84.7	79.8	81.7	1.8	81.9

table 3: Validity

Parameter	Criterion	Found	Assessment
Degradation of positive control > 60%	< 14 days	4 days	valid
Mean O2 demand of the controls	< 60 mg/L	20.9 mg/L	valid
Degradation in the toxicity flask on day 14	> 25%	*71 %	non - toxic
pH at the end of the test	6.0 - 8.5	7.3 - 7.6	valid

* Biological degradation of 71 % in the toxicity control on day 14 is calculated as follows:

D_T = (O_A - O_B) / (ThOD_T * C_T + ThOD_P * C_P)* 100%

with:

O_A             O₂-uptake in the toxicity flask in mg O₂/L on day 14 = 160 mg/L

O_B             Mean O₂-uptake of the control in mg O₂/L on day 14 = 18 mg/L

ThOD_T      Theoretical oxygen demand without nitrification test item = 1.512 mg O₂ / mg test item

ThOD_P       Theoretical oxygen demand without nitrification positive control = 1.665 mg O₂ / mg positive control

C_T             Concentration of the test item in the toxicity flask = 66 mg/L

C_P             Concentration of the positive control in the toxicity flask = 60 mg/L

Validity criteria fulfilled:

yes

Remarks:

please refer to table 3

Interpretation of results:

readily biodegradable

Conclusions:

The degree of biodegradation reached 82 % after 28 days for the test item. The degradation phase was from day 2 to day 12. The 10-day-window began on day 2, at its end (day 12), 73 % biodegradation was reached (this is stated as lag phase), staying above the pass level of 60 % given in the OECD guideline.
Therefore, when applying the 10-day-window, the test item Hydroxyacetone is readily biodegradable following OECD 301F/EU C.4-D.

Executive summary:

The study for determination of the Ready Biodegradability of hydroxyacetone was conducted following OECD guideline 301F and EU mothod C.4 -D in compliance with GLP.

The test item hydroxyacetone was tested using a concentration of 66 mg test item/L (equivalent to a theoretical oxygen demand of 100.4 mg O₂/L). Activated sludge was used as inoculum. The test was left running for 28 days. All validity criteria were met. The positive control reached the pass level of 60% on day 4 (criterion: <= 14 days).

The following data could be determined for the test item hydroxyacetone:

10-day-window: day 2 – 12

degradation at the end of 10-day-window 73 %

degradation at the end of the test 82 %

Therefore, when applying the 10-day-window, hydroxyacetone is classified as readily biodegradable following OECD 301F and EU C.4 -D, respectively.

Description of key information

activated sludge, OECD 301 F, GLP: readily biodegradable

Key value for chemical safety assessment

Biodegradation in water:

readily biodegradable

Type of water:

freshwater

Additional information

The study for determination of the Ready Biodegradability of hydroxyacetone was conducted following OECD guideline 301F and EU mothod C.4 -D in compliance with GLP.

The test item hydroxyacetone was tested using a concentration of 66 mg test item/L (equivalent to a theoretical oxygen demand of 100.4 mg O₂/L). Activated sludge was used as inoculum. The test was left running for 28 days. All validity criteria were met. The positive control reached the pass level of 60% on day 4 (criterion: <= 14 days).

The following data could be determined for the test item hydroxyacetone:

10-day-window: day 2 – 12

degradation at the end of 10-day-window 73 %

degradation at the end of the test 82 %

Therefore, when applying the 10-day-window, hydroxyacetone is classified as readily biodegradable following OECD 301F and EU C.4 -D, respectively.