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Please be aware that this old REACH registration data factsheet is no longer maintained; it remains frozen as of 19th May 2023.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

Toxicity to aquatic algae and cyanobacteria

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Administrative data

Link to relevant study record(s)

Description of key information

Algal growth inhibition:  EC50 (72 hour) - 68 mg/L (growth rate); 64 mg/L (biomass).  NOEC - 27.5 mg/L (growth rate and biomass). 

Key value for chemical safety assessment

EC50 for freshwater algae:
68 mg/L
EC10 or NOEC for freshwater algae:
27.5 mg/L

Additional information

In a 72 hour study, the cultures of Selenastrum capricornutum were exposed to an analogue of the substance, tetrahydromethylphthalic anhydride (MTHPA), at nominal concentrations of 10, 18, 32, 56 and 100 mg/L under static conditions in accordance with OECD Guideline 201. An EC50 of 68 mg/L (growth rate) and 64 mg/L (biomass) were reported and the NOEC value determined was 27.5 mg/L (growth rate and biomass).


In accordance with ECHA guidance oninformation requirements and chemical safety assessment,Chapter R.7b: Endpoint specific guidance, theErC50 endpoint is used in DNEL derivation. This is because use of values based on biomass cannot be applied to an analysis of results from a system in exponential growth without logarithmic transformation.