Sodium 4(-2-hydroxy-1-naphthylazo)naphthalenesulphonate

Endpoint summary

Description of key information

Short-term toxicity to fish:

LC50 (96h, Danio rerio) > 1000 mg/L (nominal)

Short-term toxicity to aquatic invertebrates:

EC50 (48h, Daphnia magna) > 500 mg/L (nominal)

Toxicity to aquatic algae:

ErC50 (72h, Scenedesmus subspicatus): 78 mg/L (nominal)

Additional information

Short-term toxicity to fish

The substance was tested for acute toxicity to fish following the testing procedures outlined into the OECD guideline 203. 10 fish (Danio rerio) were used for both test and control group and were exposed to the substance over a period of 96 hours. The test was run at the limit nominal concentration of 1000 mg/L. The test solution was intensely coloured and opaque. No dead occurred during the exposure period and no abnormalities were recorded; however, due to the intense colouration, a complete evaluation of the symptoms could not be performed.

Short-term toxicity to aquatic invertebrates

The acute toxicity to Daphnia magna was evaluated in a 48 -hour static test according to the EU Method C.2 of the EEC Directive 84/449. Twenty animals were exposed to five nominal concentration in the range of 31.25 to 500 mg/L and a control without any additions. In the control no immobilization of the daphnia was observed. The EC50 was found to be greater than 500 mg/L (nominal) after 48 hours.

Aquatic algae toxicity

The acute toxicity to algae of the test substance on the growth of the green alga was investigated using Scenedesmus subspicatus Chodat in a 72-hour static test, which was conducted following testing method and procedures similarly to those outlined into the OECD Guideline No. 201. Seven nominal concentrations were used, from 1.56 to 100 mg/L, and a control without any additions.

The ErC50 and EbC50 were found to be 78 mg/L and 17 mg/L (nominal), respectively.

DISCUSSION

The substance is very water soluble and it is not rapidly degradable; based on the log Kow value, the substance is not expected to bioaccumulative and the BCF is estimated to be lower than 500.

Although in none of the experiment conducted the analytical determination of tested concentration was not performed, the substance was reasonably expected to be stable over the entire test period: it is not biotically and/or abiotically readily degradable; in addition, there are no reasons to suspect the occurance of deposition/flocculation phenomena.

Based on the test results, algae resulted to be the most sensitive specie; therefore, the value obtained during the algae toxicity test has been used for the evironmental hazardous assessment, accordign to the CLP Regulation (EC) No 1272/2008 criteria.

JUSTIFICATION FOR CLASSIFICATION OR NON-CLASSIFICATION

According to the CLP Regulation (EC) No 1272/2008, Part 4: Environmental Hazards, the substances can be classified for hazardous to the aquatic environment when the following criteria are met:

A) Short-term aquatic hazard

Category Acute 1: 96 hr LC50 (for fish) and/or 48 hr EC50 (for crustacea) and/or 72 or 96 hr ErC50 (for algae or other aquatic plants) ≤ 1 mg/L;

B) Long-term aquatic hazard, substances for which adequate chronic toxicity data are not available and the substance is not rapidly degradable and/or the experimentally determined BCF ≥ 500 (or, if absent, the log K ow ≥ 4).

Category Chronic 1: 96 hr LC50 (for fish) and/or 48 hr EC50 (for crustacea) and/or 72 or 96 hr ErC50 (for algae or other aquatic plants) ≤ 1 mg/L

Category Chronic 2: 96 hr LC50 (for fish) and/or 48 hr EC50 (for crustacea) and/or 72 or 96 hr ErC50 (for algae or other aquatic plants)> 1 to ≤ 10 mg/L

Category Chronic 3: 96 hr LC50 (for fish) and/or 48 hr EC50 (for crustacea) and/or 72 or 96 hr ErC50 (for algae or other aquatic plants) > 10 to ≤ 100 mg/L

 

The substance is not rapidly degradable and the available acute toxicity tests to aquatic algae fixed the effect level that meets the criteria related to the hazard Category Chronic 3 (> 10 to ≤ 100 mg/L). Therefore, the substance is classified as Aquatic Chronic 3 according to the CLP Regulation (EC) No 1272/2008.