Reaction mass of 2-ethyl-2-(methoxymethyl)-propane-1,3-diol and 2-ethylpropane-1,3-diol

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:

From 16 October -to 13 November 2008

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study with acceptable restrictions

Remarks:

GLP compliance is not specified

Qualifier:

according to guideline

Guideline:

OECD Guideline 301 A (Ready Biodegradability: DOC Die Away Test)

Deviations:

not specified

GLP compliance:

not specified

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge, non-adapted

Details on inoculum:

The inoculum was prepared from activated sludge taken from a waste water treatment plant (Klagshamn, Sweden). The activated sludge contained 3.9 g/L suspended solids.

Duration of test (contact time):

28 d

Initial conc.:

68 mg/L

Based on:

test mat.

Parameter followed for biodegradation estimation:

DOC removal

Details on study design:

The study was performed according to the SS-EN ISO 7827:1996/OECD 301A method, which monitors the fate of dissolved organic carbon (DOC) throughout the study.

Four solutions (A-D) were produced for use in creating the test, control, inhibition, sterile and blank mediums. Stock solutions for use in creating these mediums were produced for the reaction mass of 2-ethyl-2 -(methoxymethyl)-propane-1,3-diol and 2 -ethylpropane-1,3 –diol test substance (Di-methylolpropane technical grade-US) (concentration: 1000 mg/L), reference substance (sodium acetate) (concentration: 0.0137 mg/L), and sterile medium substance (mercury(II) chloride (HgCl2)) (concentration: 0.01 mg/L).

For the test:
4 L of test medium was prepared and 2 L was added in duplicate to 2 L flasks.
2 L of control medium was prepared and added to a 2 L flask.
2 L of inhibition medium was prepared and added to a 2 L flask.
0.5 L of sterile medium was prepared and added to a 0.5 L flask.
2 L of blank medium was prepared and added to a 2 L flask.

Each flask was assigned the project number, date and type of medium, and the level in the flask marked on the flask.

Flasks were incubated in a room with diffused light at room temperature (20-25°C). To maintain aerobic conditions in the mediums and obtain stirring, air was bubbled from an air pump through a long glass tube which ended at the bottom of the flask.
Before taking samples from flasks, water loss due to evaporation was made up with deionized water.
After sampling, a new marks was made at the new medium level.

The total organic carbon (TOC) concentration was measured in each flask on day 0 and 28.
The dissolved organic carbon (DOC) concentration was measured for each period (0, 7, 14, 21 and 28 days) in each inoculated flask. The DOC concentration in the flask with sterile medium was measured only on day 0 and 28.

The filter used for DOC samples was Scheicher & Schuell, (0.45 µm, OE 67, 45 mm), boiled 3 times in deionized water to purify the filters from soluble carbon. Each boiling period lasted for at least one hour.

The percentage degradation of TOC or DOC was calculated via the following equation:
DT = (1 - çt - çBt) / (ç0 - çB0)) * 100
Where:
ç0 = the concentration of TOC or DOC, at time 0, in each test flask FT
çB0 = the concentration of TOC or DOC, at time 0, in each blank flask FB
çt = the concentration of TOC or DOC, at time t, in each test flask FT
çBt = the concentration of TOC or faxDOC, at time t, in the blank flask FB

Reference substance:

acetic acid, sodium salt

Parameter:

% degradation (DOC removal)

Remarks:

(Flask 1)

Value:

34

Sampling time:

7 d

Parameter:

% degradation (DOC removal)

Remarks:

(Flask 2)

Value:

25

Sampling time:

7 d

Parameter:

% degradation (DOC removal)

Remarks:

(Flask 1)

Value:

81

Sampling time:

14 d

Parameter:

% degradation (DOC removal)

Remarks:

(Flask 2)

Value:

80

Sampling time:

14 d

Parameter:

% degradation (DOC removal)

Remarks:

(Flask 1)

Value:

80

Sampling time:

21 d

Parameter:

% degradation (DOC removal)

Remarks:

(Flask 2)

Value:

78

Sampling time:

21 d

Parameter:

% degradation (DOC removal)

Remarks:

(Flask 1)

Value:

79

Sampling time:

28 d

Key result

Parameter:

% degradation (DOC removal)

Remarks:

(Flask 2)

Value:

81

Sampling time:

28 d

Results with reference substance:

> 90% degradation after 14 days.

TOC-content (mg/L) during the study:

Day	F(B)	F(C)	F(TI)	F(TII)	F(I)	F(S)	D(TI)	D(TII)
0	3	37	41	40	76	39	0	0
28	4	5	13	10	16	40	77	83

 

DOC-content (mg/L) during the study:

Day	F(B)	F(C)	F(TI)	F(TII)	F(I)	F(S)	D(TI)	D(TII)
0	3	42	43	76	82	42	0	0
7	5	6	31	35	24	-	34	25
14	4	4	12	12	15	-	81	80
21	5	5	13	14	16	-	80	78
28	5	5	13	12	15	43	79	81

 

Where:

FT: Test flasks containing sample and inoculum

FS: Control flask for non-biological degradation containing sample and mercury chloride

FB: Control flask for DOC contribution from the inoculum

FC: Flask containing the reference compoun (sodium acetate) for checking the activity of the inoculum

FT: Flask containing sample and the reference compound (sodium acetate) to check for any possible inhibitory effect of the sample on the inoculum

DT: Percent DOC reduction compared to day 0 after correction for the DOC contribution from the inoculum

Validity criteria fulfilled:

yes

Remarks:

Degradation of the reference compound after 14 days was >70%

Interpretation of results:

readily biodegradable

Conclusions:

In both test flasks, the test substance reaction mass of 2-ethyl-2 -(methoxymethyl)-propane-1,3-diol and 2 -ethylpropane-1,3 –diol achieved >70% biodegradation (loss of DOC) within 28 days within a 10-day window, and is therefore concluded to be readily biodegradable.

Executive summary:

The biodegradability of reaction mass of 2-ethyl-2 -(methoxymethyl)-propane-1,3-diol and 2 -ethylpropane-1,3–diol was determined according to OECD guideline 301A (DOC Die away test). The amount of biodegradation observed comprised ca. 30% after 7 days and increased to ca. 81% after 14 days., therefore reaction mass of 2-ethyl-2 -(methoxymethyl)-propane-1,3-diol and 2-ethylpropane-1,3–diol can be classified as readily biodegradable and passing the 10 day window.

Description of key information

Based on a reliable (Klimisch 2) experimental aerobic biodegradation study (according to the method SS-EN ISO 7827:1996/OECD 301A), reaction mass of 2-ethyl-2 -(methoxymethyl)-propane-1,3-diol and 2 -ethylpropane-1,3–diol is concluded to be readily biodegradable.

Key value for chemical safety assessment

Biodegradation in water:

readily biodegradable

Type of water:

freshwater

Additional information

The biodegradability of reaction mass of 2-ethyl-2 -(methoxymethyl)-propane-1,3-diol and 2 -ethylpropane-1,3–diol was determined according to OECD guideline 301A (DOC Die away test). The amount of biodegradation observed comprised ca. 30% after 7 days and increased to ca. 81% after 14 days, therefore 2-ethylpropane-1,3-diol can be classified as readily biodegradable and passing the 10 day window.