Disodium 6-hydroxy-5-[(2-methoxy-4-sulphonato-m-tolyl)azo]naphthalene-2-sulphonate

Toxicity to aquatic algae and cyanobacteria

Link to relevant study record(s)

Reference

Endpoint:

toxicity to aquatic algae and cyanobacteria

Type of information:

calculation (if not (Q)SAR)

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Data is from computational model developed by USEPA

Justification for type of information:

Data is from computational model developed by USEPA

Qualifier:

according to guideline

Guideline:

other: Modeling database

Principles of method if other than guideline:

Estimation of 96 hr EC50 value of test chemical by modelling Database - ECOSAR v.1.11. The ECOSAR Class Program is a computerized version of the ECOSAR analysis procedures as currently practiced by the Office of Pollution Prevention and Toxics (OPPT).  It has been developed within the regulatory constraints of the Toxic Substances Control Act (TSCA).  It is a pragmatic approach to SAR. The structure-activity relationships (SARs) presented in this program are used to predict the aquatic toxicity of chemicals based on their similarity of structure to chemicals for which the aquatic toxicity has been previously measured.  Most SAR calculations in the ECOSAR Class Program are based upon the octanol/water partition coefficient (Kow).  Various surfactant SAR calculations are based upon the average length of carbon chains or the number of ethoxylate units.

GLP compliance:

no

Analytical monitoring:

no

Vehicle:

no

Test organisms (species):

other: green algae

Test type:

static

Water media type:

freshwater

Total exposure duration:

96 h

Remarks on exposure duration:

Estimated data

Reference substance (positive control):

no

Key result

Duration:

96 h

Dose descriptor:

EC50

Effect conc.:

149.94 mg/L

Nominal / measured:

estimated

Conc. based on:

test mat.

Basis for effect:

growth rate

Remarks on result:

other: Neutral Organics SAR (Baseline Toxicity)

Validity criteria fulfilled:

no

Conclusions:

The estimated EC50 values for aquatic green algae after 96 hours was 149.940 mg/l on the basis of growth rate.

Executive summary:

The short-term toxicity of the test substance to green algae was predicted using EPI Suite ECOSAR version 1.10. On the basis of effects observed in a static freshwater system during a 96 hr exposure, the effect concentration (EC50) for the substance was estimated to be 149.940 mg/L. Based on this value, it can be concluded that the test chemical can be considered as non-toxic to green algae at environmentally relevant concentrations and can be considered as not-classified as per the CLP classification criteria.

 

Description of key information

The estimated EC50 values for aquatic green algae after 96 hours was 149.940 mg/l on the basis of growth rate.

Key value for chemical safety assessment

EC50 for freshwater algae:

149.94 mg/L

Additional information

Based on the predicted data for the target and experimental data for the read-across analogues, toxicity of test chemical were determined on the basis of growth inhibition of green algae. The studies are summarized as below:

The short-term toxicity of the test substance to green algae was predicted using EPI Suite ECOSAR version 1.10. On the basis of effects observed in a static freshwater system during a 96 hr exposure, the effect concentration (EC50) for the substance was estimated to be 149.940 mg/L. Based on this value, it can be concluded that the test chemical can be considered as non-toxic to green algae at environmentally relevant concentrations and can be considered as not-classified as per the CLP classification criteria.

To support the above value, freshwater algal growth inhibition test was carried out on Desmodesmus subspicatus with the test substance according to OECD Guideline 201. The stock solution 100 mg/l was prepared by dissolving red powder in OECD growth medium. Test solutions of required concentration were prepared by mixing the stock solution of the test sample with OECD growth medium and inoculum culture. 5x10(3) cells /ml algal culture was use in the study for total exposure period of 72hrs. Test concentrations used were 0, 0, 20, 30, 45, 67, 100 mg/l. Effects on the growth rate of the organism were studied.

Thus, the median effective concentration (ErC50) for the test substance after 72h, in Desmodesmus subspicatus was determined to be 285.8 mg/L. This value indicates that the substance is likely to be non-hazardous to aquatic algae and cannot be classified as toxic as per the CLP criteria.

Again as a supporting study, algal growth inhibition test was carried out on Desmodesmus subspicatus with the test substance according to OECD Guideline 201. The stock solution 200 mg/L was prepared by dissolving dark blue powder in OECD growth medium. Test solutions of required concentrations were prepared by mixing the stock solution of the test sample with OECD growth medium and inoculum culture.Test concentrations 12.5, 25, 50, 100 and 200 mg/L were prepared by diluting stock solution with OECD medium. Along with these concentrations control was also run simultaneously. Effects on the growth rate of the organism were studied. The median effective concentration (ErC50) for the test substance, on Desmodesmus subspicatus after 72h was determined to be 276.1 mg/L.

 

Thus, based on the above ErC50 values and after comparing with CLP criteria for aquatic classification of the substance it is concluded that the test substance does not exhibit toxicity to aquatic algae and hence cannot be classified.