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Please be aware that this old REACH registration data factsheet is no longer maintained; it remains frozen as of 19th May 2023.

The new ECHA CHEM database has been released by ECHA, and it now contains all REACH registration data. There are more details on the transition of ECHA's published data to ECHA CHEM here.

Diss Factsheets

Ecotoxicological information

Endpoint summary

Administrative data

Description of key information

Additional information

The registration item contains ca. 78.89% of naphthalene-2-sulphonic acid (CAS # 120-18-3) and ca. 6.5 % of naphthalene-1-sulphonic acid (CAS # 85-47-2). These two substances have the same molecular weight and are structurally almost identical. In natural environments the substance would be available as a salt due to its strong acid character. Therefore naphthalene-2-sulphonic acid and naphthalene-1-sulphonic acid and their respective salts are suitable for read across in order to fulfill the data requirements.

Several studies on aquatic organisms of three different trophic levels are available for NSA and its salts. NSA: In a test on Daphnia magna an EC50 of 34 mg/l was determined. In Scenedesmus subspicatus an EC of 74.4 mg/l was detected.


In a test on 1-NSA sodium well as on 2 -NSA ammonium salt a LC50 of 5300 mg/l and >464 <1000 mg/l rsp. was determined.

Daphnia and algae tests with a sodium and an ammonium salt determined EC50 values well above 100 mg/l.

Effects seen in the tests on NSA as acid are due to the low pH resulting from the acid in the test system and thus not considered as inherent effects.

Tests on the chronic toxicity of the substance are not available.

Thus the EC50 of 34 mg/l detected in D. magna was used as a worst case for PNEC derivation.