Aluminium ammonium bis(sulphate)

Toxicity to aquatic algae and cyanobacteria

Description of key information

One standardised test on aluminium chloride hydroxide sulfate and one non standardised tests on (NH4)2SO4 were performed on two freshwater algae species. The greatest sensitivity was related to aluminium toxicty at pH ranging between 7.1-8.4. The lowest toxicity values correspond at an ErC(50)= 32.9, an ErC10(72h)=7.2 and a NOECr= 2.4 mg/L AlNH4(SO4)2.12H2O.
AlNH4(SO4)2.12H2O.

Key value for chemical safety assessment

EC50 for freshwater algae:

32.9 mg/L

EC50 for marine water algae:

32.9 mg/L

EC10 or NOEC for freshwater algae:

7.2 mg/L

EC10 or NOEC for marine water algae:

7.2 mg/L

Additional information

No data on aluminium ammonium sufate were available on algae species. However, it is highly soluble in water, dissociating to aluminium, ammonium and sulfate. Therefore, the acute toxicity of the salt on the aquatic algae can be assessed by the effects of its dissociation products according to a read across approach.

One study according to OECD 201 guideline including GLP statement on the fresh water algae Pseudokirchneriella subcapitata with aluminum chloride hydroxide sulfate is available. This salt can be use for read across because its water solubility is higher (570g/L) than the one of the target substance (120 g/L) so the bioavailability of Aluminium is expected aslo to be higher. All the validity criteria were fulfilled and the results were based on geometric means. The ErC50 (72h) for growth rate was 0.24 mg/L Dissolved Al or 32.9 mg/L AlNH4(SO4)2.12H2O at pH=7.1-8.4. The ErC10 (72h) were determined at 3.1 mg/L Dissolved Al and 7.2 mg/L AlNH4(SO4)2.12H2O and the NOECr (72h) was 1 mg/L Dissolved Al and 2.4 mg/L AlNH4(SO4)2.12H2O. Only one valid test on algae with ammonium sulfate is available but it was not performed according to international guidelines nor GLP. This long term study on the green algae Chlorella vulgaris was performed for 21 days at an adjusted pH of 7. An EC50 (18 d) for the endpoint cell count of about 18528 mg/L AlNH4(SO4)2.12H2O was calculated. At concentrations of 20-500 mg/l N no significant differences of growth compared to control were observed. The difference observed below 20 mg/L N is expected to be due to a limitation of the N source for the growth of the algae and a NOEC growth (18d) can be determined at 500mg/L N corresponding to 16184 mg/L AlNH4(SO4)2.12H2O. These results clearly show that in the most common environmental pH, the toxicity of the salt is drived by the toxicity of aluminium. The lowest toxicity values correspond at an ErC(50)= 32.9, an ErC10(72h)=7.2 and a NOECr= 2.4 mg/L AlNH4(SO4)2.12H2O.