Disodium 6-hydroxy-5-[(4-sulphonatophenyl)azo]naphthalene-2-sulphonate

Toxicity to aquatic algae and cyanobacteria

Description of key information

Freshwater algal growth inhibition test was carried out on Desmodesmus subspicatus with the substancedisodium 6-hydroxy-5-[(4-sulfonatophenyl)diazenyl]naphthalene-2-sulfonateaccording to OECD Guideline 201.

The test substance was dissolved in DMSO and tested at the concentrations 0, 17, 30, 55, 100 and 185 mg/L. Effects on the growth rate of the organism were studied.

The median effective concentration (EC50) for the test substance,disodium 6-hydroxy-5-[(4-sulfonatophenyl)diazenyl]naphthalene-2-sulfonate, in Desmodesmus subspicatus was determined to be 113.2 mg/L.

This value indicates that the substance is not likely to be hazardous to aquatic algae as per the CLP criteria.

Key value for chemical safety assessment

EC50 for freshwater algae:

113.2 mg/L

Additional information

No. of studies were reviewed for toxicity to aquatic algae from reliable sources having Klimisch rating 1, 2 and 4. 

The summary of the results are presented below   

Sr.No	Endpoint	Effect values	Basis for effects	Duration	Species	CAS No.	Sources
1.	EC50	113.2mg/L	Population	72 hrs.	Desmodesmus subspicatus	Target cas no.2783-94-0	Test data
2.	EC50	146000mg/L	-	96hrs.	Green algae	Target cas no.2783-94-0	Predicted data from ECOSAR
3.	EC50	44524 mg/L	-	96hrs.	Green algae	Read across substance cas no.25956-17-6	Predicted data from ECOSAR

 

Based on the studies summarized in the above table for the target substance disodium 6-hydroxy-5-[(4-sulphonatophenyl)azo]naphthalene-2-sulphonate and the read across substance, the endpoint value was found to vary between EC50 = 113.2 mg/L to 146000mg/L and NOEC =15.7290 mg/L in a 72 hrs.and 96 hrs.; on the basis of Population effect. Based on the above weight of evidence values, the substance it is concluded that the test substance dose not qualifies for the aquatic toxicity.