Disodium 5-amino-4-hydroxy-3-(phenylazo)naphthalene-2,7-disulphonate

Toxicity to aquatic algae and cyanobacteria

Description of key information

 Evaluate the  toxicity of D&C Red No. 33  in  aquatic algae  was done by prediction metrhod. Prediction is done using QSAR Toolbox version 3.3.

Key value for chemical safety assessment

EC50 for freshwater algae:

122.625 mg/L

Additional information

The effect of test item disodium 5-amino-4-hydroxy-3-(phenylazo)naphthalene-2,7-disulphonate, CAS No. 3567-66-6 was studied on the growth of fresh water green algaChlorella 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.

EC50 calculated graphically through probit analysis was observed to be 19.590mg/l.

Toxicity to aquatic algae and cyanonobacteriunm for D&C Red No. 33 was predicted by QSAR Toolbox version 3.3. TheEC50 was predicted to be 122.6248703 mg\L for D&C Red No. 33in Desmodesmus subspicatus for 72 hour. Based on the above mentioned values for the chemical, it is considered that D&C Red No. 33 is not hazardous to the aquatic organisms at environmentally relevant concentrations and canbe considered not classified as per the CLP classification.

The toxicity to aquatic algae was estimated by the QSAR prediction done using the EPI Suite ECOSAR version 1.1.

In Short-term toxicity toGreen Algaetest , EC50 was estimated to be1647.016mg/Lfor2,7-Naphthalenedisulfonic acid, 5-amino-4-hydroxy-3-(phenylazo)-, disodium saltinDaphnia magna for 48 Hour. Based on the above mentioned values for the chemical, it is considered that 2,7-Naphthalenedisulfonic acid, 5-amino-4-hydroxy-3-(phenylazo)-, disodium salt is not hazardous to the aquatic organisms at environmentally relevant concentrations and can not be classified as per the CLP classification.

The toxicity to aquatic algae was estimated by the Danish (Q) SAR Database 2016.Based on the QSAR prediction done using the Danish (Q)SAR Database, the 72 hours EC50 was estimated to be1121.686 mg/lonPseudokirchneriella s. for substance disodium 5-amino-4-hydroxy-3-(phenylazo)naphthalene-2,7-disulphonate with growth inhibition effects. Thus based on this value it can be concluded that the substance can be classified as non toxic to aquatic environment as per the criteria of CLP regulation.

In a supporting study by (Luis A.V. de Luna, et.al. ,2014 ) with the similar substance (CAS NO:633-96-5),Short term toxicity study toPseudokirchneriella subcapitatawas carried out for 72 hrs. For the preparation of the test inoculum, an algae population was harvested from the cell culture and centrifuged at 2000gfor 10 min.  ICp software was used to calculate the inhibition growth concentration (IC50). One-way ANOVA andSidak-testwere also performed (OriginLab 8.5 software). Based on growth inhibition of test organism, the IC50 value was found to be > 100 mg/

Based on the experimental result,the test substanceD&C Red No.33 likely to be classified in aquatic chronic catagory 3.

But the BCF value of target substance D&C Red No. 33reported was not >= 500 as well as log Kow value is also not >=4. Thus considering the CLP Criteria for aquatic classification of the substance, it is concluded that substance does not exhibit toxicity toaquatic algae.