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Toxicity to aquatic algae and cyanobacteria

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Reference
Endpoint:
toxicity to aquatic algae and cyanobacteria
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:
QMRF report has been attached.
Qualifier:
according to
Guideline:
other: As mention below
Principles of method if other than guideline:
Prediction is done using QSAR Toolbox version 3.3
GLP compliance:
not specified
Specific details on test material used for the study:
- Name of test material : [μ-[[3,3'-[azoxybis[(2-hydroxy-p-phenylene)azo]]bis[4-hydroxynaphthalene-2,7-disulphonato]](8-)]]dicopper, tetrasodium salt
- Molecular weight : 1101.8036 g/mol
- Smiles notation : [Na+].[Na+].[Na+].[Na+].O=N(=Nc1ccc2N=Nc3c4O[Cu-2]5(Oc2c1)OS(=O)(=O)c6ccc4c(c6)cc3S(=O)(=O)O5)c7ccc8N=Nc9c%10O[Cu-2]%11(Oc8c7)OS(=O)(=O)c%12ccc%10c(c%12)cc9S(=O)(=O)O%11
- InChl : 1S/C32H22N6O17S4.2Cu.4Na/c39-25-13-17(1-7-23(25)33-35-29-27(58(50,51)52)11-15-9-19(56(44,45)46)3-5-21(15)31(29)41)37-38(43)18-2-8-24(26(40)14-18)34-36-30-28(59(53,54)55)12-16-10-20(57(47,48)49)4-6-22(16)32(30)42;;;;;;/h1-14,39-42H,(H,44,45,46)(H,47,48,49)(H,50,51,52)(H,53,54,55);;;;;;/q;2*+2;4*+1/p-8/b35-33+,36-34+,38-37+;;;;;;
- Substance type : Organic
- Physical state : Liquid
Analytical monitoring:
not specified
Vehicle:
not specified
Test organisms (species):
Pseudokirchneriella subcapitata (previous names: Raphidocelis subcapitata, Selenastrum capricornutum)
Test type:
static
Water media type:
freshwater
Total exposure duration:
72 h
Hardness:
150-200 mg/mL
Test temperature:
21°C
pH:
7.1
Nominal and measured concentrations:
Estimated data
Reference substance (positive control):
not specified
Key result
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
38.69 mg/L
Nominal / measured:
estimated
Conc. based on:
not specified
Basis for effect:
growth rate
Remarks on result:
other: Other details not known

The prediction was based on dataset comprised from the following descriptors: EC50
Estimation method: Takes average value from the 5 nearest neighbours
Domain  logical expression:Result: In Domain

(((((((((((((((("a" or "b" or "c" or "d" )  and "e" )  and "f" )  and ("g" and ( not "h") )  )  and ("i" and ( not "j") )  )  and ("k" and ( not "l") )  )  and ("m" and ( not "n") )  )  and ("o" and ( not "p") )  )  and ("q" and ( not "r") )  )  and ("s" and ( not "t") )  )  and ("u" and ( not "v") )  )  and ("w" and ( not "x") )  )  and ("y" and ( not "z") )  )  and ("aa" and ( not "ab") )  )  and ("ac" and ( not "ad") )  )  and ("ae" and "af" )  )

Domain logical expression index: "a"

Referential boundary: The target chemical should be classified as Anion OR Aromatic compound OR Azo compound OR Cation OR Hydroxy compound OR Phenol OR Sulfonic acid derivative by Organic functional groups, Norbert Haider (checkmol) ONLY

Domain logical expression index: "b"

Referential boundary: The target chemical should be classified as Alcohol, olefinic attach [-OH] OR Aliphatic Nitrogen, one aromatic attach [-N] OR Aromatic Carbon [C] OR Azo [-N=N-] OR Hydroxy, aromatic attach [-OH] OR Miscellaneous sulfide (=S) or oxide (=O) OR Olefinic carbon [=CH- or =C<] OR Oxygen, one aromatic attach [-O-] OR Suflur {v+4} or {v+6} OR Sulfonate, aromatic attach [-SO2-O] by Organic functional groups (US EPA) ONLY

Domain logical expression index: "c"

Referential boundary: The target chemical should be classified as Aryl OR Azo OR Azoxy OR Fused carbocyclic aromatic OR Overlapping groups OR Phenol OR Sulfonic acid by Organic Functional groups (nested) ONLY

Domain logical expression index: "d"

Referential boundary: The target chemical should be classified as Aryl OR Azo OR Azoxy OR Fused carbocyclic aromatic OR Naphtalene OR Phenol OR Sulfonic acid by Organic Functional groups ONLY

Domain logical expression index: "e"

Referential boundary: The target chemical should be classified as Reactive unspecified by Acute aquatic toxicity MOA by OASIS ONLY

Domain logical expression index: "f"

Referential boundary: The target chemical should be classified as Class 5 (Not possible to classify according to these rules) by Acute aquatic toxicity classification by Verhaar (Modified) ONLY

Domain logical expression index: "g"

Referential boundary: The target chemical should be classified as Acid moiety AND Phenols, Poly AND Salt by Aquatic toxicity classification by ECOSAR

Domain logical expression index: "h"

Referential boundary: The target chemical should be classified as Hydrazines by Aquatic toxicity classification by ECOSAR

Domain logical expression index: "i"

Referential boundary: The target chemical should be classified as Acid moiety AND Phenols, Poly AND Salt by Aquatic toxicity classification by ECOSAR

Domain logical expression index: "j"

Referential boundary: The target chemical should be classified as Inorganic Compound by Aquatic toxicity classification by ECOSAR

Domain logical expression index: "k"

Referential boundary: The target chemical should be classified as Acid moiety AND Phenols, Poly AND Salt by Aquatic toxicity classification by ECOSAR

Domain logical expression index: "l"

Referential boundary: The target chemical should be classified as Not Related to an Existing ECOSAR Class by Aquatic toxicity classification by ECOSAR

Domain logical expression index: "m"

Referential boundary: The target chemical should be classified as Alkali Earth AND Non-Metals by Groups of elements

Domain logical expression index: "n"

Referential boundary: The target chemical should be classified as Halogens by Groups of elements

Domain logical expression index: "o"

Referential boundary: The target chemical should be classified as Group 1 - Alkali Earth Li,Na,K,Rb,Cs,Fr AND Group 14 - Carbon C AND Group 15 - Nitrogen N AND Group 16 - Oxygen O AND Group 16 - Sulfur S by Chemical elements

Domain logical expression index: "p"

Referential boundary: The target chemical should be classified as Group 12 - Trans.Metals Zn,Cd,Hg by Chemical elements

Domain logical expression index: "q"

Referential boundary: The target chemical should be classified as Group 1 - Alkali Earth Li,Na,K,Rb,Cs,Fr AND Group 14 - Carbon C AND Group 15 - Nitrogen N AND Group 16 - Oxygen O AND Group 16 - Sulfur S by Chemical elements

Domain logical expression index: "r"

Referential boundary: The target chemical should be classified as Group 2 - Alkaline Earth Be,Mg,Ca,Sr,Ba,Ra by Chemical elements

Domain logical expression index: "s"

Referential boundary: The target chemical should be classified as Group 1 - Alkali Earth Li,Na,K,Rb,Cs,Fr AND Group 14 - Carbon C AND Group 15 - Nitrogen N AND Group 16 - Oxygen O AND Group 16 - Sulfur S by Chemical elements

Domain logical expression index: "t"

Referential boundary: The target chemical should be classified as Group 8 - Trans.Metals Fe,Ru,Os OR Group 9 - Trans.Metals Co,Rh,Ir by Chemical elements

Domain logical expression index: "u"

Referential boundary: The target chemical should be classified as Alkali Earth AND Non-Metals by Groups of elements

Domain logical expression index: "v"

Referential boundary: The target chemical should be classified as Metals by Groups of elements

Domain logical expression index: "w"

Referential boundary: The target chemical should be classified as Aryl AND Azo AND Azoxy AND Fused carbocyclic aromatic AND Naphtalene AND Phenol AND Sulfonic acid by Organic Functional groups

Domain logical expression index: "x"

Referential boundary: The target chemical should be classified as Alkene by Organic Functional groups

Domain logical expression index: "y"

Referential boundary: The target chemical should be classified as Aryl AND Azo AND Azoxy AND Fused carbocyclic aromatic AND Naphtalene AND Phenol AND Sulfonic acid by Organic Functional groups

Domain logical expression index: "z"

Referential boundary: The target chemical should be classified as Unsaturated heterocyclic fragment by Organic Functional groups

Domain logical expression index: "aa"

Referential boundary: The target chemical should be classified as Aryl AND Azo AND Azoxy AND Fused carbocyclic aromatic AND Naphtalene AND Phenol AND Sulfonic acid by Organic Functional groups

Domain logical expression index: "ab"

Referential boundary: The target chemical should be classified as Alkyl arenes by Organic Functional groups

Domain logical expression index: "ac"

Referential boundary: The target chemical should be classified as Anion AND Aromatic compound AND Azo compound AND Cation AND Hydroxy compound AND Phenol AND Sulfonic acid derivative by Organic functional groups, Norbert Haider (checkmol)

Domain logical expression index: "ad"

Referential boundary: The target chemical should be classified as Carbonic acid derivative OR CO2 derivative (general) OR No functional group found by Organic functional groups, Norbert Haider (checkmol)

Domain logical expression index: "ae"

Parametric boundary:The target chemical should have a value of log Kow which is >= 0.0785

Domain logical expression index: "af"

Parametric boundary:The target chemical should have a value of log Kow which is <= 1.6

Validity criteria fulfilled:
not specified
Conclusions:
Based on the growth rate inhibition of algae Pseudokirchneriella subcapitata by the chemical [μ-[[3,3'-[azoxybis[(2-hydroxy-p-phenylene)azo]]bis[4-hydroxynaphthalene-2,7-disulphonato]](8-)]] dicopper, tetrasodium salt, the EC50 was estimated to be 38.68 mg/l.
Executive summary:

Based on the prediction done using the OECD QSAR toolbox version 3.3 with log kow as the primary descriptor and considering the five closest read across substances, toxicity on Pseudokirchneriella subcapitata (previous names: Raphidocelis subcapitata, Selenastrum capricornutum) was predicted for [μ-[[3,3'-[azoxybis[(2-hydroxy-p-phenylene)azo]]bis[4-hydroxynaphthalene-2,7-disulphonato]](8-)]] dicopper, tetrasodium salt (75173-68-1). Based on the growth rate inhibition of algae Pseudokirchneriella subcapitata by the chemical [μ-[[3,3'-[azoxybis[(2-hydroxy-p-phenylene)azo]]bis[4-hydroxynaphthalene-2,7-disulphonato]](8-)]] dicopper, tetrasodium salt, the EC50 was estimated to be 38.68 mg/l. Based on this value it can be concluded that the substance [μ-[[3,3'-[azoxybis[(2-hydroxy-p-phenylene)azo]]bis[4-hydroxynaphthalene-2,7-disulphonato]](8-)]] dicopper, tetrasodium salt (75173-68-1) is considered to be toxic to aquatic environment and can be classified as aquatic chronic 3 as per the criteria mentioned in CLP regulation.    

Description of key information

Based on the prediction done using the OECD QSAR toolbox version 3.3 with log kow as the primary descriptor and considering the five closest read across substances, toxicity on Pseudokirchneriella subcapitata (previous names: Raphidocelis subcapitata, Selenastrum capricornutum) was predicted for [μ-[[3,3'-[azoxybis[(2-hydroxy-p-phenylene)azo]]bis[4-hydroxynaphthalene-2,7-disulphonato]](8-)]] dicopper, tetrasodium salt (75173-68-1). Based on the growth rate inhibition of algae Pseudokirchneriella subcapitata by the chemical [μ-[[3,3'-[azoxybis[(2-hydroxy-p-phenylene)azo]]bis[4-hydroxynaphthalene-2,7-disulphonato]](8-)]] dicopper, tetrasodium salt, the EC50 was estimated to be 38.68 mg/l. Based on this value it can be concluded that the substance [μ-[[3,3'-[azoxybis[(2-hydroxy-p-phenylene)azo]]bis[4-hydroxynaphthalene-2,7-disulphonato]](8-)]] dicopper, tetrasodium salt (75173-68-1) is considered to be toxic to aquatic environment and can be classified as aquatic chronic 3 as per the criteria mentioned in CLP regulation.    

Key value for chemical safety assessment

EC50 for freshwater algae:
38.68 mg/L

Additional information

Based on the various predicted data for the target chemical and experimental data for structurally and functionally similar read across chemicals study have been reviewed to determine the toxic nature of target chemical [μ-[[3,3'-[azoxybis[(2-hydroxy-p-phenylene)azo]]bis[4-hydroxynaphthalene-2,7-disulphonato]](8-)]]dicopper, tetrasodium salt (75173-68-1) on the growth of algae. The studies are as mentioned below:  

 

The first predicted study for the target chemical (100-07-2) done using the OECD QSAR toolbox version 3.3 with log kow as the primary descriptor and considering the five closest read across substances, toxicity on Pseudokirchneriella subcapitata (previous names: Raphidocelis subcapitata, Selenastrum capricornutum) was predicted for [μ-[[3,3'-[azoxybis[(2-hydroxy-p-phenylene)azo]]bis[4-hydroxynaphthalene-2,7-disulphonato]](8-)]] dicopper, tetrasodium salt (75173-68-1). Based on the growth rate inhibition of algae Pseudokirchneriella subcapitata by the chemical [μ-[[3,3'-[azoxybis[(2-hydroxy-p-phenylene)azo]]bis[4-hydroxynaphthalene-2,7-disulphonato]](8-)]] dicopper, tetrasodium salt, the EC50 was estimated to be 38.68 mg/l. Based on this value it can be concluded that the substance [μ-[[3,3'-[azoxybis[(2-hydroxy-p-phenylene)azo]]bis[4-hydroxynaphthalene-2,7-disulphonato]](8-)]] dicopper, tetrasodium salt (75173-68-1) is considered to be toxic to aquatic environment and can be classified as aquatic chronic 3 as per the criteria mentioned in CLP regulation.    

 

First predicted study was supported by the second experimental weight of evidence study for the read across chemical Brilliant black 1 (2159-30-4) from UERL lab report. Aim of this study was to assess the effect of test item tetrasodium 1-acetamido-2-hydroxy-3-(4-((4-sulphonatophenylazo)-7-sulphonato-1-naphthylazo))naphthalene-4,6-disulphonate, CAS No. 2519-30-4 on the growth of fresh water green alga Chlorella vulgaris. The study was conducted following OECD guideline 201- Alga, growth inhibition test. The chemical was analytically evaluated by using spectrophotometer, the absorbance values of each test vessel and control vessel was noted at 680nm.The BBM was taken as blank for both control and test vessels. The absorbance value of each vessel was in line with the average specific growth rate. The test solution was prepared in aseptic condition. The test item tetrasodium 1-acetamido-2-hydroxy-3-(4-((4-sulphonatophenyl azo)-7-sulphonato-1-naphthylazo))naphthalene-4,6-disulphonate was prepared by adding 21 mg of test item in 200ml of BBM to get the final concentration of 105 mg/L. This stock solution was kept for stirring for 30 minutes to obtain a homogenous solution for the experiment. The concentrations were chosen according to the available data of the test item. The remaining test solutions were prepared by dilution from the above stock solution. To have a better growth and visibility of cells, the initial cell density of the culture was kept 1 X 104cells/ml. Care was taken to have a homogeneous solution for the experiment. Test organism green alga Chlorella vulgaris were collected from National Environmental Engineering Research Institute (NEERI), Nagpur and cultivate in Bold’s Basal Medium (BBM). For the assessment of algal growth, the study was conducted in replicates. The control vessel was maintained in triplicates as recommended in the OECD guideline and the test concentrations were selected in geometric series which were maintained in duplicates. After the exposure of chemical effect were measured. To obtain a quantitative concentration-response relationship by regression analysis, a linearizing transformation of the response data into probit was performed. Using the same, effective concentration (EC) was determined. The microscopic observations were also noted in each of the test vessel. All the cells appeared healthy, round and green throughout the study duration in the control and in the test vessels cells appeared shrinked and black dotted rings observed in concentrations of 0.96mg/l, 3.072mg/l, 9.830mg/l, 31.457mg/l & 100.663mg/l. After 72 hours of exposure to test item tetrasodium 1-acetamido-2-hydroxy-3-(4-((4-sulphonatophenylazo)-7-sulphonato-1-naphthylazo))naphthalene-4,6-disulphonate (CAS No. 2519-30-4) to various nominal test concentrations, EC50 was determine to be 24.342 mg/l graphically and through probit analysis. Thus based on the EC50, chemical was concluded as toxic and can be consider to be classified as aquatic chronic 3 category as per the CLP classification criteria.

 

Similarly for another read across chemical (3567-69-9) from UERL lab study was conducted. The objective of the test was to determine the effects of Disodium 4-hydroxy-3-[(4-sulphonatonaphthyl)azo]naphthalene sulphonate CAS No. 3567-69-9 on the growth of freshwater microalgae Chlorella vulgaris. The algae were exposed to various concentrations of the test item under static conditions over a period of 72h. The growth rate relative to the control in a 72h test was taken as a parameter to observe the algal growth inhibition. Sample analytically motorized by spectrophotometer. The absorbance values of each test vessel and control vessel was noted at 680nm.TheBBM was taken as blank for both control and test vessels. The absorbance value of each vessel was in line with the average specific growth rate. The test solution was prepared in aseptic condition. The test item Disodium 4-hydroxy-3-[(4-sulphonatonaphthyl)azo] naphthalene sulphonate was prepared by adding 50 mg of test item in 250 ml of BBM to get the final concentration of 200mg/L. This stock solution was kept for stirring for 30 minutes to obtain a homogenous solution for the experiment. The test concentrations were chosen according to the available data of the test item. The remaining test solutions were prepared by dilution from the above stock solution. To have a better growth and visibility of cells, the initial cell density of the culture was kept 1 X 104cells/ml. Care was taken to have a homogeneous solution for the experiment. Test organism green alga Chlorella vulgaris were collected from National Environmental Engineering Research Institute (NEERI), Nagpur and cultivate in Bold’s Basal Medium (BBM). For the assessment of algal growth, the study was conducted in replicates. The control vessel was maintained in triplicates as recommended in the OECD guideline and the test concentrations were selected in geometric series which were maintained in duplicates. To obtain a quantitative concentration-response relationship by regression analysis, a linearizing transformation of the response data into probit was performed. Using the same, effective concentration (EC) was determined. After 72 hours of exposure to test item Disodium 4-hydroxy-3-[(4-sulphonatonaphthyl)azo]naphthalene sulphonate (CAS No. 3567-69-9) to various nominal test concentrations, EC50 was determine to be 34.823 mg/l graphically and through probit analysis. Thus based on the EC50, chemical was concluded as toxic and can be consider to be classified as aquatic chronic 3 category as per the CLP classification criteria.

 

The fourth study was used from the UERL report for the structurally and functionally similar read across chemicals (4548-53-2) which supports the classification of target chemical. The effect of the test item disodium 3-[(2,4-dimethyl-5-sulphonatophenyl)azo]-4-hydroxynaphthalene-1-sulphonate, CAS No. 4548-53-2 was studied on the growth of fresh water green alga Chlorella vulgaris. The study was conducted following OECD guideline 201- Alga, growth inhibition test. The test concentration chosen for the study were 6.25mg/l, 12.5mg/l, 25mg/l, 50mg/l, 100mg/l and 200mg/l. The test concentrations were prepared using stock solution of the test item using mineral media. The green alga was exposed to the test concentration for a period of 72 hours to observe average specific growth rate and % growth inhibition under the effect of the test item. After 72 hours of exposure to test item disodium 3-[(2,4-dimethyl-5-sulphonatophenyl)azo]- 4-hydroxynaphthalene-1-sulphonate (CAS No. 4548-53-2) to various nominal test concentrations, EC50 was determine to be 17.321mg/l graphically and through probit analysis. Based on the EC50, chemical was consider as toxic and can be consider to be classified as aquatic chronic 3 category as per the CLP classification criteria.

 

Based on the predicted data for the target chemical [μ-[[3,3'-[azoxybis[(2-hydroxy-p-phenylene)azo]] bis[4-hydroxynaphthalene-2,7-disulphonato]](8-)]]dicopper, tetrasodium salt (75173-68-1) and for the read across chemical from experimental lab reports (UERL lab), it can be concluded that the [μ-[[3,3'-[azoxybis[(2-hydroxy-p-phenylene)azo]]bis[4-hydroxynaphthalene-2,7-disulphonato]](8-)]]dicopper, tetrasodium salt (75173-68-1) is considered to be toxic to aquatic environment (aquatic algae and cyanobacteria) and can be classified as chronic 3 category as per the CLP classification criteria.