2-[[4-[ethyl(2-hydroxyethyl)amino]phenyl]azo]-6-methoxy-3-methylbenzothiazolium acetate

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:

not specified

Analytical monitoring:

not required

Vehicle:

not specified

Test organisms (species):

other: green algae

Test type:

static

Water media type:

freshwater

Total exposure duration:

96 h

Remarks on exposure duration:

Estimated data

Key result

Duration:

96 h

Dose descriptor:

EC50

Effect conc.:

34.935 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:

not specified

Conclusions:

The estimated EC50 values for aquatic green algae after 96 hours was (34.935) mg/l on the basis of growth rate.

Executive summary:

The short-term toxicity of the test substance to green algae is 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 is estimated to be 34.935 mg/L. Based on this value, it can be concluded that the test chemical can be considered as toxic to green algae at environmentally relevant concentrations and can be considered to be classified in aquatic chronic category 3 as per the CLP classification criteria.

 

Description of key information

Toxicity to aquatic algae and cyanobacteria:

The short-term toxicity of the test substance to green algae is 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 is estimated to be34.935 mg/L. Based on this value, it can be concluded that the test chemical can be considered as toxic to green algae at environmentally relevant concentrations and can be considered to be classified in aquatic chronic category 3 as per the CLP classification criteria.

 

Key value for chemical safety assessment

EC50 for freshwater algae:

34.935 mg/L

Additional information

Toxicity to aquatic algae and cyanobacteria:

The test material was evaluated for its potential to cause toxicity to aquatic algae based on the values obtained from predicted data and studied.
In prediction , the short-term toxicity of the test substance to green algae is 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 is estimated to be34.935 mg/L. Based on this value, it can be concluded that the test chemical can be considered as toxic to green algae at environmentally relevant concentrations and can be considered to be classified in aquatic chronic category 3 as per the CLP classification criteria.

In a study , the algal growth inhibition test was performed using as test material on Chlorella sp .Chlorella sp were grown on 500mL Erlenmeyer flask.Algae were added into 100mL of test water containing 50, 100, 150, 200 and 250 mg/L of 73.6, 67.9, 33.3, 25.0 and 16.6% concentration of test chemical . The flask was placed in an ambient temperature provided air and sealed with parafilm.Flasks were continuous illuminated (cool white fluorescent light approximately 120 mE/s/m2 or 6,000 lux at water level.  Determination of algal growth by measuring live cell count, Chlorophyll a, dry weight and absorbance at 720nm. The effect concentration of test chemical on Chlorella sp. was observed to be 10.8 mg/l. Based on the above effect concentration it can be considered that test material is toxic to aquatic algae and can be classified as aquatic chronic 3.

The above study was supported by another study , freshwater algal growth inhibition test was carried out on Desmodesmus subspicatus with the substance test material according to OECD Guideline 201. The test substance was dissolved in acetone and tested at the concentrations 0, 0, 0.5, 1, 2 and 4 mg/L.The stock solution 2 g/L was prepared by dissolving yellow powder in acetone. Test solutions of required concentrations were prepared by mixing the stock solution of the test sample with OECD growth medium and inoculum culture. It was not possible to test higher substance concentrations due to solubility of the test substance.Effects on the growth rate of the organism were studied. The median effective concentration (ErC50) for the test substance, in Desmodesmus subspicatus was determined to be 17.8 mg/L. Based on the ErC50, it can be concluded that the chemical was toxic and can be consider to be classified as aquatic chronic 3 as per the CLP classification criteria.

In a study , 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 pinkish red powder in DMSO/ OECD growth medium. The stock solution was kept in ultrasonic bath for 20min Test solutions of required concentration were prepared by mixing the stock solution of the test sample with OECD growth medium and inoculum culture and tested at the concentrations 0, 2.5, 5, 10, 20 and 40 mg/L. Effects on the growth rate of the organism were studied. The median effective concentration (EC50) for the test substance, in Desmodesmus subspicatus was determined to be13.4 mg/L.

These value indicates that the substance is likely to be hazardous to aquatic algae and can be classified as Aquatic Chronic 3 as per the CLP criteria.