Reaction products of aniline-4-sulfonic acid diazo with formaldehyde and resorcinol, sodium salts

Toxicity to aquatic algae and cyanobacteria

Description of key information

ErC50 72h >100 mg/L
The major effect on algal growth was related to the dyeing properties of the test item, which overruled any intrinsic toxic effect. 

Key value for chemical safety assessment

EC50 for freshwater algae:

100 mg/L

Additional information

The test was performed on a similar substance (read-across from supporting substance-structural analogue or surrogate.

The study procedures were based on the EU C.3, the OECD guideline 201 and ISO Standard 8692.

Range-finding test: Algal suspensions were exposed to concentrations of 0.1, 1.0, 10 and 100 mg/L.

An additional range-finding test was performed if the substance would indirectly inhibit the growth of green algae owing to the colour of the test solutions.

Tests were performed including both direct and indirect exposure in order to confirm the results of the range-finding tests.

Main test: concentrations tested were 1.0, 2.2, 4.6, 10, 22, 46 and 100 mg/l. The colour of the test substance treated solutions ranged from yellow to dark brown. All were clear solutions.

The actual exposure concentrations remained above 80% relative to the initial concentrations at concentrations. in both tests, a concentration dependent increase was observed in growth rate reduction and cell growth inhibition.

Algal growth was almost completely reduced at the highest concentration of 100 mg/L after indirect exposure.

More than 70% of the reduction of growth rate was related to absorption of wavelengths by the colour of the test solutions at the concentrations up to and including 100 mg/L, the maximum concentration to be tested. Hence, the actual ErC50 exceeded 100 mg/L.