2-[(2-cyanoethyl)[4-[(6-nitrobenzothiazol-2-yl)azo]phenyl]amino]ethyl acetate

Endpoint summary

Description of key information

Short term toxicity to fish

LC50 (48h) = 12 mg/l

Short-term toxicity to aquatic invertebrates

EC50 (48 h) = 67.9 % of a saturated solution (nominal loading 100 mg/l)

Toxicity to aquatic algae and cyanobacteria

ErC50 (72h) = 63.7 % of a saturated solution (nominal loading 100 mg/l)

Additional information

Apart from a toxicity study on microorganisms, only a summary of results of a 48 -h study on Rainbow trout was available on target substance; no details were provided. Consequently, the assessment for aquatic toxicity of target substance was mainly based on available data on Similar Substance 01. Details on the read across are reported in section 13.

Both target substance and read across substance are not ready biodegradable and have a low solubility in water. In particular, water solubility of target substance was measured by flask method and resulted to be less than 20 mg/l at 20 °C; a more appropriate method in case of low soluble substances, i.e. the column elution method, was used for Similar Substance 01, for which water solubility at 20 °C was less than 0.02 mg/l.

Short-term toxicity to fish

Target substance was tested for acute toxicity to Rainbow trout in a 48 -hour test, but no details on procedures and results were available. Test sample composition was 30 % dye, 69 % sodium lignosulphonate as dispersant, 1 % dedustant. As mortality was seen, an LC0 of 7 mg/l, an LC50 of 12 mg/l and an LC100 of 19.5 mg/l were determined.

Short-term toxicity to aquatic invertebrates

Similar Substance 01 was tested for acute toxicity to daphnia magna in a 48 -hour static test according to OECD guideline 202. Purity of test sample was ca. 83 %.

Nominal concentrations tested were 100 %, 50 %, 25 %, 12.5 %, 6.25 % of a saturated solution with nominal loading of 100 mg/l. Measured concentrations at 0-hour were below the LOD of 0.04 mg/l. After 48 h of exposure, immobile daphnids were seen only at the two highest concentrations, i.e. 5/20 at 50 % and 16/20 at 100 % of saturated solution; this led to an EC50 of 67.9 %.

As all tested concentrations were below the LOD and no definite data on the possible link between nominal loading and concentration in saturated solution was available, data as % of saturated solution were referred to the nominal loading of 100 mg/l. Therefore, EC50 (48h) = 67.9 mg/l.

Toxicity to aquatic algae and cyanobacteria

Similar Substance 01 was tested on toxicity to aquatic algae and cyanobacteria in a 72 -hour static test according to OECD guideline 201.

A saturated solution with a nominal loading of 100 mg test substance/l was prepared and undissolved particles were removed by membrane filtration. Components of dilution water were added to the saturated solution. Concentrations used in the test were 6.25 - 12.5 - 25.0 - 50.0 - 100 % of the saturated solution. Three replicates were tested for each concentration and six replicates for the control. Test media were clear throughout the test period. Analytical monitoring of test solutions was done via HPLC‑DAD at 0 h and recovery rates were found to be below LOD of 0.04 mg/l. 

After 72 h, growth rate inhibition was significant at the 3 highest concentrations, i.e. 8 %, 32 % and 100 %, respectively.

Similarly, yield inhibition was significant at the 3 highest concentrations, i.e. 37 %, 85 % and 100 %, respectively.

On these bases

- growth rate: ErC50 (72h) = 63.7 % of a saturated solution (100 mg/l nominal loading).

- yield: EyC50 (72h) =29.8 % of a saturated solution (100 mg/l nominal loading).

As all tested concentrations were below the LOD and no definite data on the possible link between nominal loading and concentration in saturated solution was available, data as % of saturated solution were referred to the nominal loading of 100 mg/l. Therefore, ErC50 (72h) = 63.7 mg/l and EyC50 (72h) = 29.8 mg/l.

Toxicity to microorganisms

In a study conducted according to OECD guideline 209, target substance did not cause inhibition of respiration rate of microorganisms up to a concentration of 100 mg/l after a contact time of 30 minutes.

Justification for classification or non-classification

According to the CLP Regulation (EC 1272/2008), the threshold of classification of a substance for acute aquatic toxicity is 1 mg/l. This limit is compared with LC50 (96h) for fish, EC50 (48 h) for daphnia and EC50 (72 - 96 h) for algae or aquatic plants.

As for chronic toxicity, in case of lack of chronic data, the toxic potential is identified by appropriate combinations of acute toxicity data and lack of biodegradability. The threshold of classification is 100 mg/l.

Based on EC50 values obtained, no classification for acute toxicity was applied; based on LC50 (48h) of 12 mg/l for fish, EC50 (48h) of 67.9 mg/l for daphnids and EC50 (72h) of 63.7 mg/l for algae, the substance is classified in cat. 3 for aquatic chronic toxicity according to the CLP Regulation (EC 1272/2008).