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Please be aware that this old REACH registration data factsheet is no longer maintained; it remains frozen as of 19th May 2023.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: ErC50= 65.3 mg/L; EyC50 = 61.4 mg/L; NOEC = 25 mg/L

Key value for chemical safety assessment

EC50 for freshwater algae:
65.3 mg/L
EC10 or NOEC for freshwater algae:
50 mg/L

Additional information

Algal growth inhibition to the unicellular freshwater green algaPseudokirchneriella subcapitatahas been investigated according to OECD/EU test methods. THPA was found to inhibit the growth after 72 hours exposure, EC50 values for inhibition of specific growth rate (ErC50) and yield (EyC50) being 65.3 mg/L and 61.4 mg/L, respectively. The potential for recovery from the observed effects was established.


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.