Phosphorodithioic acid, O,O-di-C1-14-alkyl esters, zinc salts

Biodegradation in water: screening tests

Link to relevant study record(s)

Reference

Endpoint:

biodegradation in water: screening tests

Type of information:

(Q)SAR

Adequacy of study:

weight of evidence

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

results derived from a valid (Q)SAR model and falling into its applicability domain, with limited documentation / justification

Justification for type of information:

The supporting QMRF report has been attached

Qualifier:

according to guideline

Guideline:

OECD Guideline 301 C (Ready Biodegradability: Modified MITI Test (I))

Principles of method if other than guideline:

The data is predicted using the OECD QSAR toolbox version 3.3 with logKow as the primary descriptor.

GLP compliance:

not specified

Specific details on test material used for the study:

- Name of test material: Dialkyl(C1-C14)dithiophosphoric acid, zinc salt
- Molecular formula: C28H60O4P2S4Zn
- Molecular weight: 716.38 g/mol
- Smiles notation: [Zn+2].CCCCCCCOP(=S)([S-])OCCCCCCC.CCCCCCCOP(=S)([S-])OCCCCCCC
- InChl: 1S/2C14H31O2PS2.Zn/c2*1-3-5-7-9-11-13-15-17(18,19)16-14-12-10-8-6-4-2;/h2*3-14H2,1-2H3,(H,18,19);/q;;+2/p-2
- Substance type: Organic
- Physical state: Liquid

Oxygen conditions:

aerobic

Inoculum or test system:

other: Microorganisms

Duration of test (contact time):

28 d

Based on:

not specified

Parameter followed for biodegradation estimation:

other: BOD

Key result

Parameter:

other: BOD

Value:

17.975

Sampling time:

28 d

Remarks on result:

other: Other details not known

Details on results:

Test substance undergoes 18% degradation by BOD in 28 days.

The prediction was based on dataset comprised from the following descriptors: BOD
Estimation method: Takes average value from the 5 nearest neighbours
Domain  logical expression:Result: In Domain

((((((("a" or "b" or "c" or "d" or "e" or "f" )  and ("g" and ( not "h") )  )  and ("i" and ( not "j") )  )  and "k" )  and "l" )  and ("m" and ( not "n") )  )  and ("o" and "p" )  )

Domain logical expression index: "a"

Referential boundary: The target chemical should be classified as Zinc metal and salts by OECD HPV Chemical Categories

Domain logical expression index: "b"

Referential boundary: The target chemical should be classified as Soluble complexes of Zinc by US-EPA New Chemical Categories

Domain logical expression index: "c"

Referential boundary: The target chemical should be classified as Alkoxy AND Thiophosphate by Organic Functional groups

Domain logical expression index: "d"

Referential boundary: The target chemical should be classified as Alkoxy AND Overlapping groups AND Thiophosphate by Organic Functional groups (nested)

Domain logical expression index: "e"

Referential boundary: The target chemical should be classified as Aliphatic Carbon [CH] AND Aliphatic Carbon [-CH2-] AND Aliphatic Carbon [-CH3] AND Miscellaneous sulfide (=S) or oxide (=O) AND Phosphite, aliphatic attach [-O-P] AND Sulfur, phosphorus attach [-S-] AND Thio-phosphorus [S=P] AND Zinc [Zn] by Organic functional groups (US EPA)

Domain logical expression index: "f"

Referential boundary: The target chemical should be classified as Anion AND Cation by Organic functional groups, Norbert Haider (checkmol)

Domain logical expression index: "g"

Referential boundary: The target chemical should be classified as No alert found by DNA binding by OASIS v.1.3

Domain logical expression index: "h"

Referential boundary: The target chemical should be classified as AN2 OR AN2 >>  Michael-type addition, quinoid structures OR AN2 >>  Michael-type addition, quinoid structures >> Quinones OR AN2 >> Schiff base formation by aldehyde formed after metabolic activation OR AN2 >> Schiff base formation by aldehyde formed after metabolic activation >> Geminal Polyhaloalkane Derivatives OR AN2 >> Shiff base formation for aldehydes OR AN2 >> Shiff base formation for aldehydes >> Geminal Polyhaloalkane Derivatives OR Non-covalent interaction OR Non-covalent interaction >> DNA intercalation OR Non-covalent interaction >> DNA intercalation >> Amino Anthraquinones OR Non-covalent interaction >> DNA intercalation >> Fused-Ring Primary Aromatic Amines OR Non-covalent interaction >> DNA intercalation >> Quinones OR Radical OR Radical >> Generation of reactive oxygen species OR Radical >> Generation of reactive oxygen species >> N,N-Dialkyldithiocarbamate Derivatives OR Radical >> Radical mechanism via ROS formation (indirect) OR Radical >> Radical mechanism via ROS formation (indirect) >> Amino Anthraquinones OR Radical >> Radical mechanism via ROS formation (indirect) >> C-Nitroso Compounds OR Radical >> Radical mechanism via ROS formation (indirect) >> Fused-Ring Primary Aromatic Amines OR Radical >> Radical mechanism via ROS formation (indirect) >> Geminal Polyhaloalkane Derivatives OR Radical >> Radical mechanism via ROS formation (indirect) >> Hydrazine Derivatives OR Radical >> Radical mechanism via ROS formation (indirect) >> Nitroarenes with Other Active Groups OR Radical >> Radical mechanism via ROS formation (indirect) >> Quinones OR Radical >> Radical mechanism via ROS formation (indirect) >> Single-Ring Substituted Primary Aromatic Amines OR SN1 OR SN1 >> Nucleophilic attack after carbenium ion formation OR SN1 >> Nucleophilic attack after carbenium ion formation >> N-Nitroso Compounds OR SN1 >> Nucleophilic attack after diazonium or carbenium ion formation OR SN1 >> Nucleophilic attack after diazonium or carbenium ion formation >> Nitroarenes with Other Active Groups OR SN1 >> Nucleophilic attack after metabolic nitrenium ion formation OR SN1 >> Nucleophilic attack after metabolic nitrenium ion formation >> Amino Anthraquinones OR SN1 >> Nucleophilic attack after metabolic nitrenium ion formation >> Fused-Ring Primary Aromatic Amines OR SN1 >> Nucleophilic attack after metabolic nitrenium ion formation >> Single-Ring Substituted Primary Aromatic Amines OR SN1 >> Nucleophilic attack after nitrenium and/or carbenium ion formation OR SN1 >> Nucleophilic attack after nitrenium and/or carbenium ion formation >> N-Nitroso Compounds OR SN1 >> Nucleophilic attack after reduction and nitrenium ion formation OR SN1 >> Nucleophilic attack after reduction and nitrenium ion formation >> Nitroarenes with Other Active Groups OR SN1 >> Nucleophilic substitution after glutathione-induced nitrenium ion formation OR SN1 >> Nucleophilic substitution after glutathione-induced nitrenium ion formation >> C-Nitroso Compounds OR SN2 OR SN2 >> Acylation involving a leaving group  OR SN2 >> Acylation involving a leaving group  >> Geminal Polyhaloalkane Derivatives OR SN2 >> Acylation involving a leaving group after metabolic activation OR SN2 >> Acylation involving a leaving group after metabolic activation >> Geminal Polyhaloalkane Derivatives OR SN2 >> Direct acting epoxides formed after metabolic activation OR SN2 >> Direct acting epoxides formed after metabolic activation >> Quinoline Derivatives OR SN2 >> DNA alkylation OR SN2 >> DNA alkylation >> Alkylphosphates, Alkylthiophosphates and Alkylphosphonates OR SN2 >> Nucleophilic substitution at sp3 carbon atom after thiol (glutathione) conjugation OR SN2 >> Nucleophilic substitution at sp3 carbon atom after thiol (glutathione) conjugation >> Geminal Polyhaloalkane Derivatives OR SN2 >> SN2 at an activated carbon atom OR SN2 >> SN2 at an activated carbon atom >> Quinoline Derivatives OR SN2 >> SN2 attack on activated carbon Csp3 or Csp2 OR SN2 >> SN2 attack on activated carbon Csp3 or Csp2 >> Nitroarenes with Other Active Groups by DNA binding by OASIS v.1.3

Domain logical expression index: "i"

Referential boundary: The target chemical should be classified as No alert found by DNA binding by OECD

Domain logical expression index: "j"

Referential boundary: The target chemical should be classified as Michael addition OR Michael addition >> P450 Mediated Activation to Quinones and Quinone-type Chemicals OR Michael addition >> P450 Mediated Activation to Quinones and Quinone-type Chemicals >> Arenes OR Michael addition >> P450 Mediated Activation to Quinones and Quinone-type Chemicals >> Hydroquinones OR Michael addition >> Polarised Alkenes-Michael addition OR Michael addition >> Polarised Alkenes-Michael addition >> Alpha, beta- unsaturated esters OR SN1 OR SN1 >> Iminium Ion Formation OR SN1 >> Iminium Ion Formation >> Aliphatic tertiary amines OR SN1 >> Nitrenium Ion formation OR SN1 >> Nitrenium Ion formation >> Aromatic azo OR SN1 >> Nitrenium Ion formation >> Aromatic nitro OR SN1 >> Nitrenium Ion formation >> Aromatic phenylureas OR SN1 >> Nitrenium Ion formation >> Primary aromatic amine OR SN1 >> Nitrenium Ion formation >> Tertiary aromatic amine OR SN2 OR SN2 >> SN2 at an sp3 Carbon atom OR SN2 >> SN2 at an sp3 Carbon atom >> Phosphates by DNA binding by OECD

Domain logical expression index: "k"

Referential boundary: The target chemical should be classified as days - weeks by Biodeg primary (Biowin 4) ONLY

Domain logical expression index: "l"

Referential boundary: The target chemical should be classified as Does NOT Biodegrade Fast by Biodeg probability (Biowin 5) ONLY

Domain logical expression index: "m"

Referential boundary: The target chemical should be classified as Non binder, MW>500 by Estrogen Receptor Binding

Domain logical expression index: "n"

Referential boundary: The target chemical should be classified as Non binder, non cyclic structure OR Non binder, without OH or NH2 group OR Strong binder, OH group by Estrogen Receptor Binding

Domain logical expression index: "o"

Parametric boundary:The target chemical should have a value of Molecular weight which is >= 535 Da

Domain logical expression index: "p"

Parametric boundary:The target chemical should have a value of Molecular weight which is <= 774 Da

Validity criteria fulfilled:

not specified

Interpretation of results:

not readily biodegradable

Conclusions:

The test chemical Dialkyl(C1-C14)dithiophosphoric acid, zinc salt was estimated to be not readily biodegradable in water.

Executive summary:

Biodegradability of Dialkyl(C1-C14)dithiophosphoric acid, zinc salt (CAS no. 68649 -42 -3) is predicted using OECD QSAR toolbox version 3.3 with logKow as the primary descriptor. Test substance undergoes 18% degradation by BOD in 28 days. Thus, based on percentage degradation, the test chemical Dialkyl(C1-C14)dithiophosphoric acid, zinc salt was estimated to be not readily biodegradable in water.

Description of key information

Biodegradability of Dialkyl(C1-C14)dithiophosphoric acid, zinc salt (CAS no. 68649 -42 -3) is predicted using OECD QSAR toolbox version 3.3 (2017) with logKow as the primary descriptor. Test substance undergoes 18% degradation by BOD in 28 days. Thus, based on percentage degradation, the test chemical Dialkyl(C1-C14)dithiophosphoric acid, zinc salt was estimated to be not readily biodegradable in water.

Key value for chemical safety assessment

Biodegradation in water:

under test conditions no biodegradation observed

Additional information

Various predicted data for the target compound Dialkyl(C1-C14)dithiophosphoric acid, zinc salt (CAS No. 68649-42-3) and supporting weight of evidence studies for its read across substance were reviewed for the biodegradation end point which are summarized as below:

 

In a prediction done by SSS (2017) using OECD QSAR toolbox version 3.3 with logKow as the primary descriptor, percentage biodegradability of test chemical Dialkyl(C1 -C14)dithio phosphoric acid, zinc salt(CAS No. 68649-42-3) was estimated.Test substance undergoes 18% degradation by BOD in 28 days. Thus, based on percentage degradation, the test chemical Dialkyl(C1-C14)dithiophosphoric acid, zinc salt was estimated to be not readily biodegradable in water.

 

In another prediction using the Estimation Programs Interface Suite (EPI suite, 2017), the biodegradation potential of the test compoundDialkyl(C1-C14)dithiophosphoric acid, zinc salt(CAS No. 68649-42-3) in the presence of mixed populations of environmental microorganisms was estimated.The biodegradability of the substance was calculated using seven different models such as Linear Model, Non-Linear Model, Ultimate Biodegradation Timeframe, Primary Biodegradation Timeframe, MITI Linear Model, MITI Non-Linear Model and Anaerobic Model (called as Biowin 1-7, respectively) of the BIOWIN v4.10 software. The results indicate that chemical Dialkyl(C1-C14)dithiophosphoric acid, zinc salt is expected to be not readily biodegradable.

 

In a supporting weight of evidence study from secondary source (HPVIS, 2017) for the read across chemical zinc bis[bis(dodecylphenyl)] bis(dithiophosphate) (CAS no. 54261-67-5), biodegradation experiment was conducted for 28 days for evaluating the percentage biodegradability of read across substance zinc bis[bis(dodecylphenyl)] bis(dithiophosphate). The study was performed according to OECD Guideline 301 F (Ready Biodegradability: Manometric Respirometry Test) under aerobic conditions at a temperature of 20 ± 1°C. A preadapted activated sludge inoculum was used for the biodegradation test obtained from domestic wastewater treatment plant. The sludge was homogenized in a blender at medium speed for approximately 2 minutes and allowed to settle for approximately 30 minutes. The supernatant was used for inoculum preadaptation. The activated sludge supernatant was combined and supplemented with vitamin free casamino acids and 25 mg/L yeast extract. The supernatant from the homogenized activated sludge was used as inoculum. Bacterial counts in the inocula were 1 x 105to 2 x 106cells/mL. 100 ml of the supplemented inoculum was combined with 900 ml of test medium within each 2-L erlenmeyer flask. The solutions were aerated with CO2 free air and test substances added incrementally at concentrations equivalent to 4, 4, and 8 mg C/L on days 0, 7, and 12, respectively. On day 14, each adapted culture was homogenized in a blender and a composite culture prepared by mixing equal volumes of the homogenized cultures. The mixture was continuously stirred in a closed flask at a constant temperature for up to 28 days. Each reactor flask is equipped with an electrolytic cell assembly, which generates oxygen to replace the amount consumed by the test mixture in the flask. The oxygen uptake in all flasks were monitored continuously and recorded automatically every 4 hours throughout the test period using the BI Data Acquisition software. The percentage degradation of test substance zinc bis[bis(dodecylphenyl)] bis(dithiophosphate) was determined to be4.2% by O2 consumption parameter in 28 days.  Thus, based on percentage degradation, zinc bis[bis(dodecylphenyl)] bis(dithiophosphate) is considered to be not readily biodegradable in nature.

 

Another biodegradation study was conducted for 28 days for evaluating the percentage biodegradability of the same read across substance zinc bis[bis(dodecylphenyl)] bis(dithio phosphate) (CAS no. 54261-67-5) (HPVIS, 2017). The study was performed according to OECD Guideline 310 B (Ready Biodegradability: CO2 in the sealed vessels (Headspace Test) and E PA OTS 796.3260 (Ready Biodegradability: Modified Sturm Test), respectively under aerobic conditions at a temperature of20 ± 3°C.A preadapted activated sludge supernatant from domestic wastewater treatment plant and soil filtrate was used as a test inoculum for the study. Soil was collected from a wooded lot to a depth of 20 cm (surface soil was not included). Prior to use, 200 gm (wet weight) of soil was suspended in 2 L of water, allowed to settle for 30 min and filtered through glass wool. Filtrate was aerated until use. Activated sludge from domestic wastewater treatment plant was sieved through a 2 mm screen, aerated for 4 hours and homogenized in a blender. The sludge was allowed to settle for 30 minutes and supernatant was removed for use. Sufficient amount of test material was added to each flask, giving 10 mg C/L in the test flasks. 100 ml of the supplemented inoculum was combined with 900 ml of test medium within each 2-L erlenmeyer flask. The solutions were aerated with CO2 free air and test substances added incrementally at concentrations equivalent to 4, 8, and 8 mg C/L on days 0, 7, and 11, respectively. On day 14, an equal volume of each culture was combined and composite inoculum screened using glass wool and homogenized in a blender. CO2 traps were removed for analysis on Days 2, 5, 11, 13, 16, 18, 23, and 29. On day 28, the test was terminated by the acidification of the test chamber to release dissolved CO2.The CO2 generated within each test chamber was trapped as K2C03 in the KOH solution and measured using a carbon analyzer.Inoculum blank and positive controls was included in the study. Abiotic and toxicity controls were not. Canola oil was used as the reference substance in the positive controls. The reference substance, canola oil, degraded 92% (2 - 5day lag period) in 28 days.The percentage degradation of test substance zinc bis[bis(dodecylphenyl)] bis(dithiophosphate) was determined to be 5.9% by CO2 evolution parameter in 28 days.  Thus, based on percentage degradation, zinc bis[bis(dodecylphenyl)] bis(dithio phosphate) is considered to be not readily biodegradable in nature.

 

For the read across chemical Dibutylbis((1-oxododecyl)-oxy) stannane (CAS no. 77-58-7), biodegradation study was conducted for 28 days for evaluating the percentage biodegradability of read across substance Dibutylbis((1-oxododecyl)-oxy) stannane (OECD SIDS, 2006). The study was performed according to OECD Guideline 301 F (Ready Biodegradability: Manometric Respirometry Test) and EU Method C.4-D (Determination of the "Ready" Biodegradability - Manometric Respirometry Test), respectively under aerobic conditions at a temperature of 20.5°C and pH 7.2. Activated sludge was used as a test inoculum obtained from an oxidation ditch, which is used to treat domestic waste water. The activated sludge was kept in a plastic flask and aerated until use. Conc. of inoculum and initial test substance concentration used in the study was 30 and 22.2 mg/l, respectively. Test medium used for the study as that specified in OECD Guideline 301. NaNO3 was added to prevent nitrogen limitation. 500 ml glass flasks was used as a test vessel for the study. 0.2666 g of the test substance was dissolved in 10 ml ethanol (Stock I). An aliquot of 250 µl of Stock I was applied to glass fibre filters (Whatman GF/C, diameter 47 mm). After being air-dried, a glass fibre filter was placed in each flask that were filled with 300 ml mineral medium. The oxygen consumption (mg O2/L) was calculated based on the respiration rate (mg O2/flask/h) as measured by an Micro-Oxymax respirometer. The oxygen consumption due to test or control substance was calculated by subtracting the mean cumulative oxygen consumption in the blanks from that of the flask under consideration. These values were then converted to the Biological Oxygen Demand (BOD) which is expressed in mg O2/mg test substance. The percentage biodegradation of the test substance was calculated as BOD/ThOD x 100 (ThOD: Theoretical Oxygen Demand). Sodium acetate, anhydrous (100 mg/l) was used as a reference substance for the study. The cumulative oxygen consumption in the toxicity control (sodium acetate and test substance) after 14 days was slightly higher than that of the inoculum activity control (sodium acetate) alone. This indicated that the test substance did not inhibit the degradation of sodium acetate at the concentration tested. Based on the combined ThOD of both substances a biodegradtion of >25% was reached which, according to the guidelines, means that the test substance is considered not toxic to the inoculum. The percentage degradation of substance Dibutylbis((1-oxododecyl)-oxy) stannane was determined to be 20, 22, 23 and 33% by using O2 consumption parameter in 14, 28 and 39 days, respectively. Thus, based on percentage degradation, Dibutylbis((1-oxododecyl)-oxy) stannane is considered to be not readily biodegradable in nature.

 

In a supporting weight of evidence study from authoritative database (J-CHECK, 2017) for the read across chemical 1-Decanaminium, N-decyl-N,N-dimethyl-, chloride (CAS no. 7173-51-5), biodegradation experiment was conducted for 28 days for evaluating the percentage biodegradability of read across substance 1-Decanaminium, N-decyl-N,N- dimethyl-, chloride. The study was performed according to OECD Guideline 301 C (Ready Biodegradability: Modified MITI Test (I)) and other guideline "Biodegradation test of a chemical substance using a microorganism etc." provided in "the Notice on the Test Method Concerning New Chemical Substances", respectively. Concentration of inoculum i.e, sludge used was 30 mg/l and initial test substance conc. used in the study was 100 mg/l, respectively. The percentage degradation of substance 1-Decanaminium, N-decyl-N,N-dimethyl-, chloride was determined to be 0% by O2 consumption, BOD, Test mat. analysis and LC-MS parameter in 28 days.Thus, based on percentage degradation,1-Decanaminium, N-decyl-N,N-dimethyl-, chloride is considered to be not readily biodegradable in nature.

 

On the basis of above results for target chemical Dialkyl(C1-C14)dithiophosphoric acid, zinc salt (from OECD QSAR toolbox version 3.3 and EPI suite, 2017) and for its read across substance (from authoritative database J-CHECK and secondary source), it can be concluded that the test substance Dialkyl(C1-C14)dithiophosphoric acid, zinc salt can be expected to be not readily biodegradable in nature.