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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:
weight of evidence
Study period:
03th June 1994 - 24th June 1994
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
guideline study without detailed documentation
Remarks:
non-GLP
Justification for type of information:
This endpoint study record is part of a Weight of Evidence approach comprising this guideline study (OECD 301A; non-GLP; RL2) and another guideline study (OECD 301F; non-GLP; RL2) on the analogue substance "Esters of sodium hydrogen phosphate with myo-Inositol, plant-derived" (old CAS 14306-25-3) with a similar structure and similar intrinsic properties (Read-across approach). For the justification of the Read-across approach, please refer to the analogue justification attached to IUCLID section 13.
The derived results from the studies don`t contradict each other and are sufficient to fulfil the information requirements of this endpoint as further explained in the provided endpoint summary.
Qualifier:
according to
Guideline:
OECD Guideline 301 A (Ready Biodegradability: DOC Die Away Test)
Version / remarks:
1992
Deviations:
yes
Remarks:
The degradation was followed for 14 days instead of 28 days. Deviation is uncritical because biodegradation of test item was >90% after 14 days.
GLP compliance:
no
Remarks:
Study was conducted 1994 from the Japan Food Research Laboratory, which is authorized by the Japanese Government
Specific details on test material used for the study:
The test item in this study corresponds to the substance "Esters of phosphoric acid with myo-Inositol, plant-derived (old CAS 83 -86 -3). Only the the water content is different - Instead of a water content of 30%, the test item contains 50% water. The 50% aqueous solution is the customary form in the market. The higher water content does not affect the result of this study.
Oxygen conditions:
aerobic
Inoculum or test system:
activated sludge, domestic, non-adapted
Details on inoculum:
- Source of inoculum/activated sludge:
Activated sludge from the aeration tank of Minamitama Sewage Treatment Plant (Inagi-shi, Tokyo)
- Pretreatment:
a) Washing step (3 times): The activated sludge was suspended in deionized water, and centrifuged.
b) Determination of suspended solid of the sludge: Centrifugation method in according to "Test method of waste water" (1984).
- Concentration of sludge:
900 mg suspended solids/L with deionized water
- Water filtered:
no
Duration of test (contact time):
14 d
Initial conc.:
730 mg/L
Based on:
test mat.
Initial conc.:
40 mg/L
Based on:
DOC
Parameter followed for biodegradation estimation:
DOC removal
Reference substance:
aniline
Parameter:
% degradation (DOC removal)
Value:
>= 98.6 - <= 100
Sampling time:
14 d
Key result
Parameter:
% degradation (DOC removal)
Value:
>= 97.6 - <= 99.4
Sampling time:
7 d
Details on results:
The pass level is > 70% removal of DOC in a 10 -day window within 28 -days. Since the biodegradation of the test substance after 7 days was already >90%, the substance is considered to be readily biodegradable according to the OECD criteria.
Results with reference substance:
The percentage degradation of aniline, which was used as a reference substance, was 100% after 7 days, and this meant the test was regarded as valid.

The percentage degradation of the test substance in 7 days was over 90%.

The percentage degradation of the test substance in 14 days was over 90%.

The percentage degradation of aniline, which was used as a reference substance, was above 90% in 7 days, and this meant the test was regarded as valid.

The percentage degradation is shown in the following table. Each value in the Table below was obtained by calculation of the value obtained by the test.

 Test flask    Degradation (%) in days       
 7 14  14 (mean) 
Test suspension 1 > 90 (98.9)  > 90 (98.6)  > 90 (99.5)       
Test suspension 2 > 90 (97.6)  > 90 (100) 
Test suspension 3 > 90 (99.4) > 90 (100) 
 Abiotic sterile control < 10 < 10 
 Adsorption control < 10 < 10   -
 Aniline Reference > 90 (100) > 90 (99.7)   -

DOC (mg/L)

DOC (mg/L) are shown in the following Table. Each value in the table was substracted blank except abiotic sterile control and adsorption control.

 Test flask    DOC (mg/L) in days       
 0 14 
 Test suspension 1 36.7  < 1   < 1 
 Test suspension 2 37.3  < 1  < 1 
 Test suspension 3 36.3  < 1  < 1 
 Abiotic sterile control 38.0  36.2  36.9 
 Adsorption control 37.7  34.0  34.4 
 Aniline Reference 79.5  < 1  < 1 
Validity criteria fulfilled:
yes
Remarks:
refer to "any other information on results incl. tables
Interpretation of results:
readily biodegradable
Conclusions:
The test item was determined to be readily biodegradable in water (OECD 301A).
Executive summary:

In this guideline study according to OECD 301 A the ready biodegradability of the substance was investigated.

A mixed microbial population of the activated sludge from sewage treatment plant Inagi-shi, Tokyo, Japan was inoculated with a nominal concentration of 730 mg/L test substance and incubated for 14 d under controlled conditions in the dark. Degradation was followed by the removal of DOC at 7 days and 14 days. An inoculum blank, a reference control, an abiotic sterile control and an adsoprtion control were run in parallel. The degradation rate was < 10% for the abiotic sterile and adsorption control after 14 days and > 90% for the reference substance after 7 d. Therefore, the test was regarded as valid. Since the biodegradation of the test substance after 7 days was already >90% (pass level: > 70% removal of DOC in 10 -day window within 28 -day peridod) the substance is considered to be readily biodegradable according to the OECD criteria.

Endpoint:
biodegradation in water: ready biodegradability
Type of information:
read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
weight of evidence
Justification for type of information:
Please refer to the analogue justification attached to IUCLID section 13.
Reason / purpose:
read-across source
Key result
Parameter:
% degradation (O2 consumption)
Value:
>= 71 - <= 77
Sampling time:
28 d
Conclusions:
According to SS-EN ISO 9408:2000, the test is valid if the degradation of the reference compound in the control bottle exceeds 50% after 5 days, if the degradation of the reference compound exceeds 40% in the inhibition bottle and if the pH values in the test bottles are between 6 and 8.

According to OECD guidelines for testing chemicals a test compound is regarded as readily biodegradable if the removal of ThOD within 28 days is greater than 60%. The pass value has to be reached in a 10 -day window within the 28 -day period of the test. The 10 -day window begins when the degree of biodegradation has reached 10% ThOD and must end before day 28 of the test.

All these criteria were fulfilled, which means that the test substance can be regarded as readily biodegradable.

Executive summary:

In the guideline study according to OECD 301F a measured volume of inoculated mineral medium, containing 826 mg/l test item as the nominal sole source of organic carbon, was stirred in a closed flask at a constant temperature for 28 days. The consumption of oxygen by the microbial population during biodegradation of the test substance (corrected for uptake by blank inoculum, run in parallel) was determined from the change in pressure in the apparatus and was expressed as a percentage of ThOD. The derived degradation rate was 71 -77% for the test substance after 28 d, 69% for the reference substance after 14 d and 91% for the inhibition (toxicity) control after 14 d . Due to the fact that the degradation rate of the toxicity control was >25% after 14 d, toxic effects of the test substance to the inoculum can be excluded. Since the test substance reached the pass level of 60% biodegradation within 28 d (within the 10 -d window) it is considered to be readily biodegradable according to the OECD criteria.

The read-across from the source to the target is in accordance with Regulation (EC) No. 1907/2006 Annex XI, 1.5 and is explained in the analogue justification in IUCLID Section 13. The differences between the target and the source are unlikely to lead to differences in their readily biodegradability in water.

Endpoint:
biodegradation in water: ready biodegradability
Type of information:
experimental study
Adequacy of study:
weight of evidence
Study period:
16th Nov 2007 - 14th Dec 2007
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
guideline study without detailed documentation
Remarks:
non-GLP
Justification for type of information:
For the read-across justification please refer to the analogue justification attached to IUCLID section 13.
This endpoint study record is part of a Weight of Evidence approach comprising a read-across approach (this guideline study OECD 301F) and an experimental guideline study (OECD 301A). Both data sources agree in the readily biodegradability of the substance and are sufficient to fulfil the information requirements as further explained in the provided endpoint summary.
Qualifier:
according to
Guideline:
OECD Guideline 301 F (Ready Biodegradability: Manometric Respirometry Test)
Version / remarks:
1994
Deviations:
not specified
Qualifier:
according to
Guideline:
ISO DIS 9408 (Ultimate Aerobic Biodegradability - Method by Determining the Oxygen Demand in a Closed Respirometer)
Deviations:
not specified
GLP compliance:
no
Remarks:
Study is from 2007
Specific details on test material used for the study:
The Test material is a 50% aqueous solution of the solid target substance "Esters of sodium hydrogen phosphate with myo-Inositol, plant derived (old CAS 14306-25-3)", which water content is between 0.1-10% (hygroscopic solid). The 50% aqueous solution is the customary form in the market. The water content does not influence the general outcome of this study.
Oxygen conditions:
aerobic
Inoculum or test system:
activated sludge, non-adapted
Details on inoculum:
- Source of inoculum/activated sludge: Activated sludge from Klagshamn waste water plant in Malmö, Sweden.
- Method of cultivation: not specified
- Storage conditions: aerated (but not specified)
- Storage length: not specified
- Preparation of inoculum for exposure: not specified
- Pretreatment: not specified
- Concentration of sludge: The concentration of suspended solids in the activated sludge was 4.5 g per litre. The final concentration of suspended silids in the mediums was 30 mg per litre.
Duration of test (contact time):
28 d
Initial conc.:
826 mg/L
Based on:
test mat.
Remarks:
which gave a ThOD of 100 mg/l
Parameter followed for biodegradation estimation:
O2 consumption
Details on study design:
TEST CONDITIONS
- Composition of medium: according the OECD guideline 301
- Test temperature: 20.9 - 21.9
- pH: start: 7.4 / end: 6.9-7.0
- pH adjusted: yes
- Suspended solids concentration: the final conc. of suspended solids in mediums was 30 mg per litre
- Continuous darkness: yes (not specified)
- Other: continous stirring

TEST SYSTEM
- Culturing apparatus: closed manometric respirometer (model 2173 B) (made by Hach). The equipment contained six bottles and each of them was connected to a manomter. The contents in the bottles were stirred with a magnetic stirrer.
- Number of culture flasks/concentration: 2
- Measuring equipment:
- Details of trap for CO2: potassium hydroxide solution

SAMPLING
- Sampling method: change of pressure in the test flasks was measured by means of a manometric method

CONTROL AND BLANK SYSTEM
- Inoculum blank: 2 replicates (412 ml blank medium + inoculum (inoculums oxygen demand))
- Procedure control: 1 replicate (347 ml control medium + inoculum + reference compound (activity of inoculum))
- Toxicity control: 1 replicate (152 ml Inhibition medium + inoculum + test item + reference compound (toxicity of test article))

Reference substance:
acetic acid, sodium salt
Key result
Parameter:
% degradation (O2 consumption)
Value:
>= 71 - <= 77
Sampling time:
28 d
Details on results:
The pass value of > 60% degradation was reached in a 10 -day window within the 28 -day period of the test. Hence, the test item can be regarded as readily biodegradable.
The 10-day window for the test item began after 3 days (biodegradation > 10%) and a biodegradation of > 60% was reached for the test item after 7-10 days.
Results with reference substance:
The reference compound was sufficiently degraded to 69% after 14 days and 70% after 28 days.

Validity criteria

a) Validity criteria according to SS-EN ISO 9408:2000

 Criterion from SS-EN ISO 9408:2000 guideline

 Outcome  Validity criterion fulfilled
 Degradation of the reference compound in the control bottle exceeds 50% after 5 days  62%  yes
 Degradation of the reference compound exceeds 40% in the inhibition bottle  > 40% yes 
 pH values in the test bottles are between 6 and 8  pH 6.9 - 7.0 (after 28 days)  yes

b) Validity criteria according to OECD guideline 301

Criterion from the OECD guideline 301

 Outcome Validity criterion fulfilled 

Difference of extremes of replicate values of the removal of the test chemical at the plateau, at the end of the test or at the end of the 10-d window, as appropriate, is less than 20%.

7.79%   yes

Percentage degradation of the reference compound has reached the pass levels by day 14.

 > 60%

yes 

The oxygen uptake of the inoculum blank is normally 20-30 mg O2/L and should not be greater than 60 mg/L in 28 days.

 14 -18 mg/l

yes 

 

Biochemical Oxygen Demand (mg/l)

Date Day Temp Blank 1 Blank 2 Cont Test 1 Test 2 Inhib
20060331 0 21.6 0 0 0 0 0 0
20060401 1
20060402 2
20060403 3 21.5 2 8 46 16 15 68
20060404 4 21.5 7 11 57 43 42 111
20060405 5 21.7 9 12 62 59 54 132
20060406 6 20.9 11 13 64 68 60 147
20060407 7 21.5 13 14 69 77 70 158
20060408 8
20060409 9
20060410 10 21.3 17 14 71 90 82 174
20060411 11 21.3 18 15 71 90 85 174
20060412 12 21.5 18 15 71 90 85 174
20060413 13 21.5 18 15 71 91 86 174
20060414 14 21.3 18 15 71 92 87 179
20060415 15
20060416 16
20060417 17 21.9 18 15 71 93 87 179
20060418 18 21.1 18 15 71 93 87 179
20060419 19 21.3 18 15 71 93 87 179
20060420 20 21.1 18 15 71 93 87 179
20060421 21
20060422 22
20060423 23
20060424 24 21.6 18 14 71 93 87 179
20060425 25 21.6 18 14 71 93 87 179
20060426 26 21.5 18 14 71 93 87 179
20060427 27 21.7 18 14 71 93 87 179
20060428 28 21.6 18 14 71 93 87 179

Percentage Biodegradation of ThOD (%)

Date Day Control Test 1 Test 2 Inhibition
20060331 0 0 0 0 0
20060401 1 0 0 0 0
20060402 2 0 0 0 0
20060403 3 52 11 10 36
20060404 4 62 34 33 57
20060405 5 67 49 44 68
20060406 6 67 55 48 76
20060407 7 70 63 56 81
20060408 8
20060409 9
20060410 10 70 74 66 89
20060411 11 69 73 68 88
20060412 12 69 73 68 88
20060413 13 69 74 69 88
20060414 14 69 76 70 91
20060415 15
20060416 16
20060417 17 70 77 71 91
20060418 18 70 77 71 91
20060419 19 70 77 71 91
20060420 20 70 77 71 92
20060421 21
20060422 22
20060423 23
20060424 24 70 77 71 92
20060425 25 70 77 71 92
20060426 26 70 77 71 92
20060427 27 70 77 71 92
20060428 28 70 77 71 92
Validity criteria fulfilled:
yes
Remarks:
(For further information see section "Any other information on results inc. tables".)
Interpretation of results:
readily biodegradable
Conclusions:
According to SS-EN ISO 9408:2000, the test is valid if the degradation of the reference compound in the control bottle exceeds 50% after 5 days, if the degradation of the reference compound exceeds 40% in the inhibition bottle and if the pH values in the test bottles are between 6 and 8.
 
According to OECD guidelines for testing chemicals a test compound is regarded as readily biodegradable if the removal of ThOD within 28 days is greater than 60%. The pass value has to be reached in a 10 -day window within the 28 -day period of the test. The 10 -day window begins when the degree of biodegradation has reached 10% ThOD and must end before day 28 of the test.

All these criteria were fulfilled for the test substance which means that it can be regarded as readily biodegradable.
Executive summary:

In the guideline study according to OECD 301F a measured volume of inoculated mineral medium, containing 826 mg/l test item as the nominal sole source of organic carbon, was stirred in a closed flask at a constant temperature for 28 days. The consumption of oxygen by the microbial population during biodegradation of the test substance (corrected for uptake by blank inoculum, run in parallel) was determined from the change in pressure in the apparatus and was expressed as a percentage of ThOD. The derived degradation rate was 71 -77% for the test substance after 28 d, 69% for the reference substance after 14 d and 91% for the inhibition (toxicity) control after 14 d . Due to the fact that the degradation rate of the toxicity control was >25% after 14 d, toxic effects of the test substance to the inoculum can be excluded. Since the test substance reached the pass level of 60% biodegradation within 28 d (within the 10 -d window) it is considered to be readily biodegradable according to the OECD criteria.

The read-across from the source to the target is in accordance with Regulation (EC) No. 1907/2006 Annex XI, 1.5 and is explained in the analogue justification in IUCLID Section 13. The differences between the target and the source are unlikely to lead to differences in their readily biodegradability in water.

Description of key information

Readily biodegradable according to the OECD criteria (97.6 - 99.4% degradation after 7 d, OECD 301A; 71 -77% degradation after 28 d, OECD 301F)

Key value for chemical safety assessment

Biodegradation in water:
readily biodegradable

Additional information

The biodegradation of the substance was evaluated by a weight of evidence approach. This approach was based on a guideline study (non-GLP, RL2) and a read-across to the Similar Substance 01 "Esters of sodium hydrogen phosphate with myo-Inositol, plant-derived" (old CAS 14306 -25 -3). Justification for Read Across is given in Section 13 of IUCLID.

 

In the guideline study according to OECD 301 A the ready biodegradability of the substance was investigated.

A mixed microbial population of the activated sludge from sewage treatment plant Inagi-shi, Tokyo, Japan was inoculated with a nominal concentration of 730 mg/L test substance and incubated for 14 d under controlled conditions in the dark. Degradation was followed by the removal of DOC at 7 days and 14 days. An inoculum blank, a reference control, an abiotic sterile control and an adsoprtion control were run in parallel. The degradation rate was < 10% for the abiotic sterile and adsorption control after 14 days and > 90% for the reference substance after 7 d. Therefore, the test was regarded as valid. Since the biodegradation of the test substance after 7 days was already >90% (pass level: > 70% removal of DOC in 10 -day window within 28 -day peridod) the substance is considered to be readily biodegradable according to the OECD criteria.

In the second guideline study according to OECD 301F a measured volume of inoculated mineral medium, containing 826 mg/l test item (analogue substance) as the nominal sole source of organic carbon, was stirred in a closed flask at a constant temperature for 28 days. The consumption of oxygen by the microbial population during biodegradation of the test substance (corrected for uptake by blank inoculum, run in parallel) was determined from the change in pressure in the apparatus and was expressed as a percentage of ThOD. The derived 28 d degradation rate was 71 -77% for the test substance and 69% for the reference control after 14 d. Due to the fact that the degradation rate of the toxicity control was >25% after 14 d, toxic effects of the test substance to the inoculum can be excluded. Since the test substance reached the pass level of 60% biodegradation within 28 d it is considered to be readily biodegradable according to the OECD criteria.

 

Overall Conclusion for biodegradablity in water:

The weight of evidence approach was based on two guideline studies (OECD 301F and OECD 301A. The results from the experimental study (RL2) were confirmed by the read-across on the analogue substance (Similar Substance 01). In conclusion, the substance "Esters of phosphoric acid with myo-Inositol, plant-derived" (old CAS 83 -86 -3) is considered to be readily biodegradable in water.