Phosphorodithioic acid, O,O-di-dodecyl-esters, zinc salts, neutral and basic

Biodegradation in water: screening tests

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

key study

Justification for type of information:

Please refer to the analogue justification attached to IUCLID section 13.

Reason / purpose for cross-reference:

read-across source

Parameter:

% degradation (O2 consumption)

Value:

< 5

Sampling time:

5 d

Remarks on result:

other: mean of two test concentrations

Parameter:

% degradation (O2 consumption)

Value:

< 5

Sampling time:

15 d

Remarks on result:

other: mean of two test concentrations

Parameter:

% degradation (O2 consumption)

Value:

< 5

Sampling time:

27 d

Remarks on result:

other: mean of two test concentrations

Reference 2

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

experimental study

Adequacy of study:

key study

Study period:

1992

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

EU Method C.6 (Degradation: Chemical Oxygen Demand)

Deviations:

not specified

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 301 D (Ready Biodegradability: Closed Bottle Test)

Deviations:

not specified

GLP compliance:

no

Oxygen conditions:

aerobic

Inoculum or test system:

sewage, industrial (adaptation not specified)

Details on inoculum:

Source of inoculum/activated sludge (e.g. location, sampling depth, contamination history, procedure): effluent of a domestic sewage treatment plant located in Hennef, Germany
- Water filtered: yes
- Type and size of filter used, if any: inoculum was filtered through a coarse folded filter and the first 200 mL discarded

Duration of test (contact time):

27 d

Initial conc.:

2.49 mg/L

Based on:

test mat.

Initial conc.:

3.91 mg/L

Based on:

test mat.

Parameter followed for biodegradation estimation:

O2 consumption

Details on study design:

TEST CONDITIONS
- Composition of medium: filtered sewage
- Test temperature: 20 +/- 1 °C
- pH: not stated
- Continuous darkness: yes


TEST SYSTEM
- Culturing apparatus: 300 mL flasks
- Number of culture flasks/concentration: 2
- Measuring equipment: dissolved oxygen content was determined using the oxygen measuring apparatus Syland Temp-O2-Mat 4002


SAMPLING
- Sampling frequency: day 5, 15 and 27
- Sampling method: oxygen content was measured within the test flasks


CONTROL AND BLANK SYSTEM
- Inoculum blank: the oxygen content of the mineral nutrient solution without inoculum and without test substance as well as without test substance but with inoculum was tested on day 0, 5, 15 and 27
- other: to test the inhibition effect of the test substance to the inoculum, an additional test run was prepared containing 3.91 mg test substance/L and 5.0 mg sodium acetate/L


STATISTICAL METHODS: no statistics were performed

Reference substance:

acetic acid, sodium salt

Remarks:

5 mg/L and 10 mg/L

Parameter:

% degradation (O2 consumption)

Value:

< 5

Sampling time:

5 d

Remarks on result:

other: mean of 2 test concentrations

Parameter:

% degradation (O2 consumption)

Value:

< 5

Sampling time:

15 d

Remarks on result:

other: mean of 2 test concentrations

Parameter:

% degradation (O2 consumption)

Value:

< 5

Sampling time:

27 d

Remarks on result:

other: mean of two test concentrations

Details on results:

The biological oxygen demand was <5% of the chemical oxygen demand in both test concentrations at all sampling dates.

Sodium acetate in the inhibition test (medium contained test substance as well as reference substance) was degraded by 80% at day 27 which indicates that the test concentration did not have inhibitory effects on the inoculum.

Results with reference substance:

The biodegradation of sodium acetate was >95% .

TEST SUBSTANCE

Results of oxygen measurements during the test     Oxygen content [mg O2/L ] Test duration [d] 0 5 15 27 Medium without test substance, without inoculum 1 2 mean 8.77 8.86 8.82 8.73 8.80 8.77 8.79 8.51 8.65 8.50 8.48 8.49 Medium without test substance, with inoculum 1 2 mean 8.72 8.80 8.76 8.67 8.74 8.71 8.63 8.70 8.67 8.55 8.42 8.49 Medium with 2.49 mg test substance/L and inoculum 1 2 mean 8.91 8.95 8.93 8.72 8.73 8.73 8.68 8.71 8.70 8.43 8.56 8.50 Medium with 3.91 mg test substance/L and inoculum 1 2 mean 8.92 8.91 8.92 8.67 8.70 8.69 8.58 8.63 8.61 8.40 8.27 8.34

Decrease in oxygen content of test medium Test substance concentration [mg/L] Biological oxygen demand [mg/L] Day 5 Day 15 Day 27 2.49 -0.02 -0.03 -0.01 3.91 0.02 0.06 0.15   Biodegradation of test substance Test substance concentration [mg/L] %BOD of COD [mg/L] Day 5 Day 15 Day 27 2.49 <5 <5 <5 3.91 <5 <5 <5 Mean <5 <5 <5 COD: Chemical oxygen demand of test substance (2.26 mg O2/mg)

REFERENCE SUBSTANCE (SODIUM ACETATE)

Results of oxygen measurements during the test     Oxygen content [mg O2/L ] Test duration [d] 0 5 15 27 Medium without test substance, without inoculum 1 2 mean 8.77 8.86 8.82 8.73 8.80 8.77 8.79 8.51 8.65 8.50 8.48 8.49 Medium without test substance, with inoculum 1 2 mean 8.72 8.80 8.76 8.67 8.74 8.71 8.63 8.70 8.67 8.55 8.42 8.49 Medium with 5.0 mg reference substance/L and inoculum 1 2 mean 8.83 8.80 8.82 5.87 5.85 5.86 5.48 5.49 5.49 3.90 4.05 3.98 Medium with 10.0 mg reference substance/L and inoculum 1 2 mean 8.84 8.82 8.83 2.90 2.88 2.89 2.41 2.32 2.37 0.95 0.87 0.91   Decrease in oxygen content of test medium Reference substance concentration [mg/L] Biological oxygen demand [mg/L] Day 5 Day 15 Day 27 5.0 2.85 3.18 4.51 10.0 5.82 6.30 7.58   Biodegradation of reference substance Reference substance concentration [mg/L] %BOD of ThOD [mg/L] Day 5 Day 15 Day 27 5.0 73 81 >95 10.0 75 81 >95 Mean 74 81 >95 ThOD: theoretical oxygen demand (0.78 mg O2/mg for sodium acetate

The test is considered to be valid as validity criteria were fulfilled (more than 60% of the reference substance was degraded after 27 days; the oxygen consumption in the test medium (blank control) did not exceed 0.4 mg/L and was < 0.6 mg/L in the inoculum control after 14 and 27 d).

Validity criteria fulfilled:

yes

Interpretation of results:

under test conditions no biodegradation observed

Conclusions:

Not readily biodegradable according to the OECD criteria (<5% degradation after 27 d, EU Method C.6).

Executive summary:

No data are available on the biodegradation in water of Phosphorodithioic acid, O,O-di-dodecyl-esters, zinc salts, neutral and basic (CAS No.4563-56-8). Therefore data from the analogue substance zinc bis[O,O-bis(2-ethylhexyl)] bis(dithiophosphate) (CAS 4259-15-8) were used for read across. This read-across is in accordance with Regulation (EC) No. 1907/2006 Annex XI, 1.5 In this case of read-across, the best suited (highest degree of structural similarity, nearest physico-chemical properties) read-across substance was used for the assessment. This read-across is justified in within the analogue justification in IUCLID Section 13.

A study was performed to assess the biodegradation in water of Zinc bis[O,O-bis(2-ethylhexyl)] bis(dithiophosphate) (CAS 4259-15-8) (Rheinchemie, 1992). The method followed was according to the EU Method C.6 and equivalent to the OECD Guidelines for Testing of Chemicals No 301 (1994) under non-GLP. A industrial sewage was used as inoculum. The initial test item concentrations were 2.49 and 3.91 mg/L. The test item was found to be not readily biodegradable under the test conditions at the end of the 27 -day exposure period.The biodegradation of the reference substance (sodium acetat) was >95%.

Description of key information

Not readily biodegradable according to the OECD criteria (<5% degradation after 27 d, EU Method C.6).

Key value for chemical safety assessment

Biodegradation in water:

under test conditions no biodegradation observed

Additional information

No data are available on the biodegradation in water of Phosphorodithioic acid, O,O-di-dodecyl-esters, zinc salts, neutral and basic (CAS No.4563-56-8). Therefore data from the analogue substance zinc bis[O,O-bis(2-ethylhexyl)] bis(dithiophosphate) (CAS 4259-15-8) were used for read across. This read-across is in accordance with Regulation (EC) No. 1907/2006 Annex XI, 1.5 In this case of read-across, the best suited (highest degree of structural similarity, nearest physico-chemical properties) read-across substance was used for the assessment. This read-across is justified in within the analogue justification in IUCLID Section 13.

A study was performed to assess the biodegradation in water of Zinc bis[O,O-bis(2-ethylhexyl)] bis(dithiophosphate) (CAS 4259-15-8) (Rheinchemie, 1992). The method followed was according to the EU Method C.6 and equivalent to the OECD Guidelines for Testing of Chemicals No 301 (1994) under non-GLP. A industrial sewage was used as inoculum. The initial test item concentrations were 2.49 and 3.91 mg/L. The test item was found to be not readily biodegradable under the test conditions at the end of the 27 -day exposure period.The biodegradation of the reference substance (sodium acetat) was >95%.