3,7-bis(diethylamino)phenoxazin-5-ium acetate

Toxicity to aquatic algae and cyanobacteria

Link to relevant study record(s)

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:

The supporting QMRF report has been attached

Qualifier:

according to guideline

Guideline:

other: as mentioned below

Principles of method if other than guideline:

Prediction is done using 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 (IUPAC name): 3,7-bis(diethylamino)phenoxazin-5-ium acetate
- Molecular formula: C22H29N3O3
- Molecular weight: 383.489 g/mol
- Smiles notation: c1c2nc3ccc(cc3[o+]c2cc(N(CC)CC)c1)N(CC)CC.C(C)(=O)[O-]
- InChl: 1S/C20H26N3O.C2H4O2/c1-5-22(6-2)15-9-11-17-19(13-15)24-20-14-16(23(7-3)8-4)10-12-18(20)21-17;1-2(3)4/h9-14H,5-8H2,1-4H3;1H3,(H,3,4)/q+1;/p-1
- Substance type: Organic
- Physical state: Solid

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

Test temperature:

23 ± 1°C

Reference substance (positive control):

not specified

Key result

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

0.579 mg/L

Nominal / measured:

estimated

Conc. based on:

test mat.

Basis for effect:

growth rate

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" )  and ("c" and ( not "d") )  )  and ("e" and ( not "f") )  )  and ("g" and ( not "h") )  )  and "i" )  and ("j" and "k" )  )

Domain logical expression index: "a"

Referential boundary: The target chemical should be classified as SN1 AND SN1 >> Nitrenium Ion formation AND SN1 >> Nitrenium Ion formation >> Tertiary aromatic amine by DNA binding by OECD

Domain logical expression index: "b"

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

Domain logical expression index: "c"

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

Domain logical expression index: "d"

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

Domain logical expression index: "e"

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

Domain logical expression index: "f"

Referential boundary: The target chemical should be classified as Triazines, Aromatic by Aquatic toxicity classification by ECOSAR

Domain logical expression index: "g"

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

Domain logical expression index: "h"

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: "i"

Referential boundary: The target chemical should be classified as Very fast by Bioaccumulation - metabolism half-lives ONLY

Domain logical expression index: "j"

Parametric boundary:The target chemical should have a value of log Kow which is >= 1.42

Domain logical expression index: "k"

Parametric boundary:The target chemical should have a value of log Kow which is <= 6.56

Validity criteria fulfilled:

not specified

Conclusions:

The median Effective concentration (EC50) value for 3,7-bis(diethylamino)phenoxazin-5-ium acetate on Pseudokirchneriella subcapitata in a 72 hour study was estimated to be 0.578 mg/L on the basis of effects on growth rate.

Executive summary:

Using the OECD QSAR toolbox version 3.3 with log kow as the primary descriptor and considering the five closest read across substances, the short term toxicity on aquatic algae and cyanobacteria was predicted for target substance 3,7-bis(diethylamino)phenoxazin-5-ium acetate (CAS no. 79916 -07 -7). EC50 value was estimated to be 0.578 mg/l for Pseudokirchneriella subcapitata for 72 h duration. Based on this value it can be concluded that the substance 3,7-bis(diethylamino)phenoxazin-5-ium acetate is considered to be toxic to aquatic environment and can be considered to be classified in aquatic acute 1/ chronic 1 category as per the CLP classification criteria.

Description of key information

Using the OECD QSAR toolbox version 3.3 (2017) with log kow as the primary descriptor and considering the five closest read across substances, the short term toxicity on aquatic algae and cyanobacteria was predicted for target substance 3,7-bis(diethylamino)phenoxazin-5-ium acetate (CAS no. 79916 -07 -7). EC50 value was estimated to be 0.578 mg/l for Pseudokirchneriella subcapitata for 72 h duration. Based on this value it can be concluded that the substance 3,7-bis(diethylamino)phenoxazin-5-ium acetate is considered to be toxic to aquatic environment and can be considered to be classified in aquatic acute 1 / chronic 1 category as per the CLP classification criteria.

Key value for chemical safety assessment

EC50 for freshwater algae:

0.578 mg/L

Additional information

Predicted data for the target chemical 3,7-bis(diethylamino)phenoxazin-5-ium acetate(CAS No. 79916-07-7) and various supporting weight of evidence studies for its closest read across substances with logKow as the primary descriptorwere reviewed for toxicity to aquatic algae and cyanobacteria endpoint to summarize the following information:

 

Short term toxicity on aquatic algae and cyanobacteria of target chemical3,7-bis(diethylamino)phenoxazin-5-ium acetate(CAS No. 79916-07-7) is predicted using the OECD QSAR toolbox version 3.3 with log kow as the primary descriptor and considering the five closest read across substances (2017).On the basis of effects observed in a static freshwater system, the effect concentration EC50 value for the substance is estimated to be 0.578 mg/l for Pseudokirchneriella subcapitata for 72 duration.

 

In a weight of evidencestudy from authoritative database (HSDB, 2017) of the read across chemical 4-(dimethylamino)-3-methylphenyl N-methylcarbamate (CAS no. 2032-59-9), short term toxicity to Chlamydomonas variabilis (green algae) study was carried out for 24 hrs. The study was based on the effects of the read across compound 4 -(dimethylamino)-3 -methylphenyl N-methylcarbamate on Chlamydomonas variabilis in a static fresh water system. Based on the inhibitory effect on the test organism Chlamydomonas variabilis, the 24 hr IC50 value was determined to be 0.0008 mg/l, respectively.

 

Another short term toxicity to aquatic algae study was carried out for 28 hrs for the same read across chemical 4-(dimethylamino)-3-methylphenyl N-methylcarbamate (CAS no. 2032-59-9) (ECOTOX database, 2017).The study was based on the effects of the read across compound 4 -(dimethylamino)-3 -methylphenyl N-methylcarbamate (CAS no. 2032 -59 -9) on algae in a static fresh water system at a temperature of 12°C. Based on effect on physiology of the test organism algae, the 28 hr EC50 value was determined to be 0.56 mg/l, respectively.

 

Thus, based on the overall reported results for target chemical3,7-bis(diethylamino)phenoxazin-5-ium acetate(OECD QSAR toolbox version 3.3, 2017) and for its read across substance (fromauthoritative database HSDB and ECOTOX),it can be concluded that the test substance3,7-bis(diethylamino)phenoxazin-5-ium acetatecan be considered as toxic to aquatic algae and cyanobacteria and can be considered to be classified in aquatic acute 1/ chronic 1 category as per the CLP classification criteria.