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Biodegradation in water: screening tests

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Endpoint:
biodegradation in water: ready biodegradability
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: The data are from an official Japanese data base on experimental data for biodegradation that is well recognised by authorities. The study was performed under standard conditions, but no details on the test are available.
Qualifier:
according to guideline
Guideline:
OECD Guideline 301 C (Ready Biodegradability: Modified MITI Test (I))
Version / remarks:
Information from OECD SIDS dossier for 1,2,3-trichloropropane
Principles of method if other than guideline:
The test was performed with a concentration of 100 mg/L test solution, 30 mg/L activated sludge and a total volume of test solution of 300 mL at 25 °C for 28 days.
GLP compliance:
no
Oxygen conditions:
aerobic
Inoculum or test system:
activated sludge (adaptation not specified)
Details on inoculum:
no data
Duration of test (contact time):
28 d
Initial conc.:
100 mg/L
Based on:
test mat.
Parameter followed for biodegradation estimation:
O2 consumption
Remarks:
Termed "BOD" in the short summary
Parameter followed for biodegradation estimation:
TOC removal
Parameter followed for biodegradation estimation:
test mat. analysis
Remarks:
Analysis by gas chromatography
Details on study design:
The concentration of the test substance was 100 mg/L. The concentration of activated sludge (as concentration of suspended solid) was 30 mg/L. The volume of the test solution was 300 mL. The test was performed at 25 °C for 28 days. The test was carried out in three parallel series.
Reference substance:
not specified
Parameter:
% degradation (O2 consumption)
Value:
0
Sampling time:
28 d
Parameter:
% degradation (TOC removal)
Value:
0
Sampling time:
28 d
Parameter:
% degradation (test mat. analysis)
Value:
7.7
St. dev.:
11.6
Sampling time:
28 d
Details on results:
The biodegradation was 0 % (based on BOD), 0 % (based on TOC) and between 0 and 22 % with an average of 7.7 % (based on test material analysis)
Results with reference substance:
no data
Validity criteria fulfilled:
yes
Interpretation of results:
under test conditions no biodegradation observed
Conclusions:
The substance 1,2,3-trichloropropane is not biodegradable under the conditions of a standard screening test on biodegradation in water.
Executive summary:

The biodegradation in water of the test substance 1,2,3-trichloropropane was studied under aerobic conditions in a standard screening test performed in three parallel series in accordance with OECD Guideline No. 301C. To this end 100 mg/L test substance and 30 mg/L activated sludge were added to a total test volume of 300 mL. The test was performed at 25 °C for 28 days. The biodegradation was estimated by determination of the BOD (0 % degradation), the TOC (0 % degradation) and gas chromatographic analysis of the test material content (0 to 22 % degradation, mean 7.7 %).

In conclusion, the study found that 1,2,3 -trichloropropane is not readily biodegradable in water under aerobic conditions.

Endpoint:
biodegradation in water: inherent biodegradability
Type of information:
experimental study
Adequacy of study:
key study
Study period:
2003
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: The study was conducted according to OECD guideline 302B and in accordance with GLP
Reason / purpose for cross-reference:
reference to same study
Reason / purpose for cross-reference:
reference to other study
Qualifier:
according to guideline
Guideline:
OECD Guideline 302 B (Inherent biodegradability: Zahn-Wellens/EMPA Test)
Principles of method if other than guideline:
OECD guideline
GLP compliance:
yes
Specific details on test material used for the study:
Details on properties of test surrogate or analogue material (migrated information):
Not applicable
Oxygen conditions:
aerobic
Inoculum or test system:
activated sludge, industrial, non-adapted
Details on inoculum:
- Source of inoculum/activated sludge (e.g. location, sampling depth, contamination history, procedure): Midland Municipal Wastewater Treatment Plant (Midland, Michigan)
- Storage conditions: Upon return to the laboratory, the activated sludge was washed twice with tap water, and dispersed in mineral medium.
- Water filtered: no
Duration of test (contact time):
28 d
Initial conc.:
150 mg/L
Based on:
test mat.
Parameter followed for biodegradation estimation:
test mat. analysis
Parameter followed for biodegradation estimation:
DOC removal
Details on study design:
EXPERIMENTAL DESIGN:
Reaction mixtures containing 1,2-dichloropropane were prepared in 1-liter glass bottles constructed with glass baffles. The vessels were sealed with caps equipped with two sampling ports. One port contained a sampling valve with a Luer lock fitting connected to Teflon tubing that permitted sampling of the reaction mixture. A second port was fitted with a plastic sleeve to insert a fiber optic probe for headspace oxygen measurements. The probe was protected in a #18 gauge stainless steel needle that was inserted through the sampling valve into the vessel headspace.

Portions of activated sludge (240 mL) were combined with 255 mL of mineral medium and adjusted to a final volume of 500 mL with aniline stock solution or water, as appropriate. Test mixtures were prepared by adding 65 uL of 1,2-dichloropropane (density 1.16 mg/mL) to duplicate vessels to obtain a nominal concentration of 150 mg/L 1,2-dichloropropane.

SAMPLING
- Sampling frequency: 0 (3 hours after addition of 1,2-dichloropropane), 1, 2, 7, 14, 21, and 28 days
- Additional samples were collected following the conclusion of the experiment on day 31 for additional DOC analyses
- Sampling method: A disposable 20-mL plastic syringe was connected to the sampling port of the reaction vessel with a Luer lock fitting and approximately 25 mL of the reaction mixture was removed. The sample was passed through a 0.45 mm nylon membrane filter containing a glass fiber pre-filter. Filters were pre-rinsed with water prior to use. For samples collected on days 28 and 31, centrifugation was used to separate the sludge solids from the liquid phase prior to filtering in order to reduce excessive backpressures encountered in the filtering step. The filtrate was collected in a 40-mL vial chilled in ice to minimize volatilization losses of 1,2-dichloropropane.
- Sample storage before analysis: Following collection of the filtrate, a 1-mL subsample was removed and mixed with 1-mL of 25% phosphoric acid solution in a 20-mL headspace vial that was chilled in ice.

CONTROL AND BLANK SYSTEM
- Inoculum blank: Inoculum control mixtures containing only the inoculated medium were included to allow measurement of background DOC concentrations in the reaction mixtures and possible interferences in the compound specific analysis by GC.
- Toxicity control: Toxicity control mixtures amended with 72 mg/L aniline and 150 mg/L 1,2-dichloropropane were used to determine whether the test material was inhibitory to the microbial inoculum.
Reference substance:
aniline
Preliminary study:
Preliminary studies indicated that even minimal aeration of the reaction mixtures resulted in extensive losses of 1,2-dichloropropane by volatilization.
Test performance:
No data
Parameter:
% degradation (DOC removal)
Value:
0
Sampling time:
28 d
Details on results:
No biodegradation of 1,2-dichloropropane was observed during the test. No difference was observed in loss of 1,2-dichloropropane in viable mixtures compared to abiotic controls over 28 days.

Aniline (reference compound) was extensively degraded in positive control mixtures (96% in 14 days), thereby confirming the viability of the microbial inoculum.

Extensive degradation of aniline in toxicity control mixtures containing PDC (98% in 14 days) showed that PDC was not inhibitory to the inoculum under the test conditions.
Results with reference substance:
Aniline (reference compound) was extensively degraded in positive control mixtures (96% in 14 days), thereby confirming the viability of the microbial inoculum. Similar extensive degradation of aniline in the presence of 1,2-dichloropropane (98% in 14 days) demonstrated that the test material was not inhibitory to the inoculum under the test conditions.

None

Validity criteria fulfilled:
yes
Interpretation of results:
under test conditions no biodegradation observed
Conclusions:
1,2-Dichloropropane did not meet the criteria of inherent biodegradability under the conditions of a modified OECD Method 302B test.
Executive summary:

The inherent biodegradability of 1,2-dichloropropane was assessed using a modification of the Zahn-Wellens/EMPA test (OECD Method 302B). Reaction mixtures were prepared by dispersing activated sludge from a municipal wastewater treatment plant in a standard mineral medium. Reaction mixtures were amended with 150 mg/L 1,2 -dichloropropane and incubated in closed vessels to minimize the loss of test material due to volatilization. Oxygen concentrations in the headspace of the vessels were monitored and oxygen gas was added as necessary to ensure that aerobic conditions were maintained. The reaction mixtures were continuously mixed and incubated at 22 ± 1 °C for 28 days. Compound specific analyses of 1,2 -dichloropropane in the liquid phase of the reaction mixtures by gas chromatography with flame ionization detection (GC-FID) showed little difference in test material concentrations over time between viable and abiotic control mixtures (biologically inhibited with mercuric chloride).

Thus, 1,2 -dichloropropane did not biodegrade under the conditions of this test. Measurement of dissolved organic carbon (DOC) concentrations in the reaction mixtures confirmed the results of the GC-FID analyses.

Aniline (reference compound) was extensively degraded in positive control mixtures (96% in 14 days), thereby confirming the viability of the microbial inoculum. Similar extensive degradation of aniline in the presence of 1,2 -dichloropropane (98% in 14 days) demonstrated that 1,2 -dichloropropane was not inhibitory to the inoculum under the test conditions.

Description of key information

Key value for chemical safety assessment

Biodegradation in water:
not biodegradable
Type of water:
freshwater

Additional information

The biodegradation in water of the test substance TCP was studied under aerobic conditions in a standard screening test (MITI 1992a) performed in three parallel series in accordance with OECD Guideline No. 301C. To this end 100 mg/L test substance and 30 mg/L activated sludge were added to a total test volume of 300 mL. The test was performed at 25 °C for 28 days. The biodegradation was estimated by determination of the BOD (0 % degradation), the TOC (0 % degradation) and gas chromatographic analysis of the test material content (0 to 22 % degradation, mean 7.7 %). In conclusion, the study found that TCP is not readily biodegradable in water under aerobic conditions.

The inherent biodegradability of the closely related 1,2-dichloropropane was assessed using a modification of the Zahn-Wellens/EMPA test (DOW 2003). The test was in accordance with OECD Guideline No. 302B. Reaction mixtures were prepared by dispersing activated sludge from a municipal wastewater treatment plant in a standard mineral medium. Reaction mixtures were amended with 150 mg/L 1,2 -dichloropropane and incubated in closed vessels to minimize the loss of test material due to volatilization. Oxygen concentrations in the headspace of the vessels were monitored and oxygen gas was added as necessary to ensure that aerobic conditions were maintained. The reaction mixtures were continuously mixed and incubated at 22 ± 1 °C for 28 days. Compound specific analyses of 1,2 -dichloropropane in the liquid phase of the reaction mixtures by gas chromatography with flame ionization detection (GC-FID) showed little difference in test material concentrations over time between viable and abiotic control mixtures (biologically inhibited with mercuric chloride). Thus, 1,2 -dichloropropane did not biodegrade under the conditions of this test. Measurement of dissolved organic carbon (DOC) concentrations in the reaction mixtures confirmed the results of the GC-FID analyses. The studies indicate that a biodegradation of TCP in the aquatic environment is unlikely under aerobic conditions. The CICAD 56 document for TCP (WHO) discusses a preliminary study on the co-oxidative transformation of the substance by the ammonia-oxidising bacterium Nitrosomonas europaea (Vannelli et al. 1990). In the experiment, the chlorinated substrate at a concentration of about 6.8 mmol/L was reduced to a residual amount of 91 % in the absence of the energy source ammonia and to 77 % in the presence of ammonia after 24 hours of incubation.