Propane-1,2-diol, propoxylated

Biodegradation in water and sediment: simulation tests

Administrative data

Endpoint:

biodegradation in water: simulation testing on ultimate degradation in surface water

Type of information:

experimental study

Adequacy of study:

other information

Study period:

2004

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: The study was conducted according to OECD guideline 301F and in accordance with GLP

Cross-reference

Reason / purpose for cross-reference:

reference to same study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2004

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 306 (Biodegradability in Seawater)

Deviations:

no

Principles of method if other than guideline:

NA

GLP compliance:

yes (incl. QA statement)

Test material

Test material information

Constituent 1

Reference substance name:

25657-08-3

EC Number:

607-772-3

Cas Number:

25657-08-3

IUPAC Name:

25657-08-3

Constituent 2

Reference substance name:

tetrapropylene glycol

IUPAC Name:

tetrapropylene glycol

Details on test material:

Name of test material (as cited in study report): tetrapropylene glycol.
Purity test date: > 95%.

Specific details on test material used for the study:

Details on properties of test surrogate or analogue material (migrated information):
NA

Radiolabelling:

no

Study design

Oxygen conditions:

aerobic

Inoculum or test system:

natural water

Details on source and properties of surface water:

Details on collection (e.g. location, sampling depth, contamination history, procedure): Offshore location in the Gulf of Mexico, approximately 10 miles southeast of Freeport, Texas. The sampling location (28°50’38”N, 95°08’05”W) was sufficiently distant from any known point sources of petroleum exploration and production pollution. The total depth was 20.7 meters and surface water temperature was 27°Celcius. Water was pumped from approximately 1 meter below surface into several sterile 4-L amber glass bottles. The bottles were sealed with PTFE-lined caps, packed in ice, and shipped by overnight courier to the laboratory.
Storage conditions: 4L amber glass bottles and were sealed with PTFE-lined caps and packed in ice.
Storage length: 48 hour.
Temperature (°C) at time of collection: 27°C.
pH at time of collection: 8.2 (Unfiltered sea water).
Electrical conductivity: 45.3 mmho/cm (Unfiltered sea water).
Hardness (CaCO3): 6022 (Unfiltered sea water).
Dissolved organic carbon (%): 2.0 mg/L (Unfiltered sea water).
Biomass (e.g. in mg microbial C/100 mg, CFU or other): 6.9 ± 1.0 x 10 2.
Water filtered: yes.
Type and size of filter used, if any: Whatman 113V filter paper (> 30 micrometer).

Details on source and properties of sediment:

NA

Details on inoculum:

Source of inoculum/activated sludge (e.g. location, sampling depth, contamination history, procedure): Offshore location in the Gulf of Mexico, approximately 10 miles southeast of Freeport, Texas. The sampling location (28°50’38”N, 95°08’05”W) was sufficiently distant from any known point sources of petroleum exploration and production pollution. The total depth was 20.7 meters and surface water temperature was 27° Celcius. Water was pumped from approximately 1 meter below surface into several sterile 4-L amber glass bottles. The bottles were sealed with PTFE-lined caps, packed in ice, and shipped by overnight courier to the laboratory. Seawater was filtered (>30 µm) and fortified with basal minerals prior to use.

Duration of test (contact time):

> 0 - <= 64 d

Initial test substance concentration

Initial conc.:

> 0 - <= 50 mg/L

Based on:

DOC

Parameter followed for biodegradation estimation:

DOC removal

Details on study design:

TEST CONDITIONS:
Volume of test solution/treatment: 500 ml.
Composition of medium: Test chemical in nutrient-fortified sea water.
Test temperature: 20.8.
pH:
pH adjusted: yes.
CEC (meq/100 g):
Aeration of dilution water:
Suspended solids concentration:
Continuous darkness: yes.
Any indication of the test material adsorbing to the walls of the test apparatus:
Other:

TEST SYSTEM:
Culturing apparatus: 1-liter reaction vessels.
Number of culture flasks/concentration:
Method used to create aerobic conditions: aeration.
Method used to create anaerobic conditions:
Measuring equipment: MicroOxymax respirometer for CO2 and O2 and Shimadzu model TOC-V analyzer equipped with an ASI-V autosampler for DOC.

Test performed in closed vessels due to significant volatility of test substance: not applicable.
Test performed in open system:
Details of trap for CO2 and volatile organics if used:
Other:

SAMPLING:
Sampling frequency: six-hour sample intervals.
Sampling method:
Sterility check if applicable: not applicable.
Sample storage before analysis: Yes.
Other:

CONTROL AND BLANK SYSTEM:
Inoculum blank:
Abiotic sterile control:
Toxicity control:
Other:

STATISTICAL METHODS:

Reference substance

Reference substance:

benzoic acid, sodium salt

Results and discussion

Test performance:

Not required

% Degradation

% Degr.:

ca. 31.3

St. dev.:

1

Parameter:

DOC removal

Sampling time:

64 d

Remarks on result:

other: Tetrapropylene Glycol has primary degradation based on DOC is 31.3% and 19.4% mineralization. So the degradation based on DOC removal did not exceed the 50% level within the 64-day test period.

Transformation products:

no

Details on transformation products:

NA

Evaporation of parent compound:

no

Volatile metabolites:

no

Residues:

no

Details on results:

TEST CONDITIONS:
Aerobicity (or anaerobicity), moisture, temperature, and other experimental conditions maintained throughout the study: Yes.

Results with reference substance:

In the present test, the lag period for benzoate biodegradation was 3 days, and 10 additional days were required for DOC removal to exceed 50% . Therefore, the lag phase observed for benzoate biodegradation in this test falls within the range indicated by OECD, while the observed time for 50% DOC removal was slightly longer than expected. These results for benzoate biodegradation do not invalidate the results of this test. Rather, the relatively slow degradation of benzoate indicates that the inoculum used in this study provides a conservative representation of the microbial activity occurring in marine environments, and this happened due to the dilute microbial populations and lack of prior exposure to synthetic organic chemicals.

Any other information on results incl. tables

Test Chemical	DOC Added asTest Material(mg/L)	Mean Blank-Corrected  Day 0 Day64		Mean % DOCRemoval after 64 days(n=2, ± 1 SD)	Mean % Mineralizedafter 64 days(n=2, ± 1 SD)
Benzoate	20.3	21.1	0.2	98.9 ± 1.5	70.2 ± 0.8
TePG	29.1	31.4	21.2	31.3 ± 7.0	19.4 ± 9.1

Applicant's summary and conclusion

Validity criteria

Validity criteria fulfilled:

yes

Conclusions:

Tetrapropylene glycol (TePG) has potential for primary biodegradation in marine environments, based on 31.3% DOC removal and 19.4% mineralization in the OECD Guideline 306 test. Based on these results, TePG is not expected to persist indefinitely in marine or estuarine environments.

Executive summary:

This is a GLP study which follows the OECD TG 306 Biodegradability in Seawater test. In this study, biodegradation reaction mixtures (500 mL) were prepared by adding the test chemical to nutrient-fortified seawater at a concentration of approximately 50 mg/L, providing approximately 30 mg/L dissolved organic carbon (DOC). DOC removal was measured at 0, 7, 14, 21, 29, 42, 50, and 64 days. Mineralization of the test chemical was also measured by connecting the test vessels to a MicroOxymax respirometer (Columbus Instruments, Columbus, OH, USA), which measured cumulative carbon dioxide evolution relative to unamended inoculum blanks. An abiotic control mixture was prepared by adding the test material to seawater test medium containing mercuric chloride at 250 mg/L. Positive control mixtures were prepared with sodium benzoate (20 mg/L DOC as benzoate) to confirm the viability of the microbial inoculum. A single toxicity control mixture was prepared by combining benzoate and the test material in the seawater test medium to determine if the test material was inhibitory to the seawater microorganisms. The reaction mixtures were continuously stirred at 150 r.p.m. and maintained at an average temperature (± 1SD) of 20.8 ± 0.1° C for 64 days. Tetrapropylene Glycol has potential for primary biodegradation in marine environments, based on 31.3% DOC removal and 19.4% mineralization in the OECD Guideline 306 test; thus TePG is not expected to persist indefinitely in marine or estuarine environments.