Trisodium 1-(1-naphthylazo)-2-hydroxynaphthalene-4',6,8-trisulphonate

Endpoint summary

Description of key information

LC50 (96 h) in fish (Danio rerio)> 1000 mg/l.

EC50 (48 h) in aquatic invertebrates (Daphnia magna) > 100 mg/l.

NOEC (7 d) in aquatic plants (lemna) for frond number and dry weight both growth rate and yield = 100 mg/l

EC50 (3h) in microorganisms > 1000 mg/l.

Additional information

Assessment on aquatic toxicity of the target substance relied on information of the substance itself as well as on data on a read across substance, i.e. Similar Substance 01 (further evaluation are reported in section 13)

The two substances showed a high structural similarity, a similar physiscochemical profile and a similar ecotoxicological profile, based on available data on aquatic invertebrates. Therefore, the read across approach was considered as appropriate and reliable.

In particular, data on Similar Substance 01 was used to assess short-term toxicity to fish.

In available studies, exposure to test substance was reported in terms of nominal concentrations. No indication possible precipitation and/or degradation of tested substance was reported.

Fish

Similar Substance 01 was tested for acute toxicity to fish in 96 -hour static studies, based on OECD guideline 203; observations for mortality were done at 1, 4, 24, 48, 72 and 96 h after start of exposure.

In particular, Similar Substance 01 was tested at concentration of 1000 mg/l and control, with 10/fish/concentration.

LC0 = 1000 mg/l and LC50 > 1000 mg/l, as nominal concentration.

Aquatic invertebrates

In an available study, the substance was tested for acute toxicity to aquatic invertebrates up to 48 -hour, based on EU method C.2; observations for effects on mobility were done at 24 and 48 h after start of exposure.

The substance was tested under static exposure conditions, using concentrations of 1, 5, 10, 50 and 100 mg/l and a control, with 20 animals per concentration divided in 2 replicates.

EC0 = 100 mg/l and EC50 > 100 mg/l, as nominal concentration.

Aquatic plants

In an available study, the target substance was tested for toxicity to aquatic plants, i.e. lemna minor, using a 7 -day exposure according to OECD guideline 221. Observation for growth rate and yield inhibition of frond number and dry weight were done at day 0, 3, 5 and 7. Appearance of plants at the end of the test was noted. Based on preliminary results, the study was conducted as limit test and no effects were reported at the concentration of 100 mg/l a.i..

NOEC = 100 mg/l for effects of inhibition on fronds number and dry weight, as nominal concentration.

Microorganisms

In the available study, the test material was tested for toxicity to microorganisms up to 3-hour, based on EU method C.11. The potential toxicity of the substance to microorganisms was assessed as inhibition of respiration rate, leading to EC0 = 1000 mg/l and EC50 > 1000 mg/l as nominal concentration.

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.

In available studies, no indication of toxicity of the substance was seen.

Based on results with fish, daphnia and aquatic plants, no classification for acute aquatic toxicity was applied. 

No chronic toxicity data is available from long-term studies. In case of lack of chronic data, the potential for chronic toxicity is identified by appropriate combinations of acute toxicity data and lack of biodegradability. The threshold of classification is 100 mg/l.

Based on available results, no classification for chronic or acute aquatic toxicity was applied according to the CLP Regulation (EC 1272/2008).