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Please be aware that this old REACH registration data factsheet is no longer maintained; it remains frozen as of 19th May 2023.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

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Description of key information

With high probability acutely not harmful to aquatic algae and cyanobateria.

Key value for chemical safety assessment

EC50 for freshwater algae:
600.5 mg/L
EC10 or NOEC for freshwater algae:
92.6 mg/L

Additional information

The toxicity of 1-Methyl-2-pyrrolidone (NMP, CAS 872-50-4) to aquatic algae and cyanobacteria was studied in a guideline study following German Industrial Standard DIN 38412 Part 9. The test was performed under static conditions, using Desmodesmus subspicatus as test organism (BASF AG, 1989). 

The data of the original report were re-evaluated using ToxRat v2.08 in order to obtain an EC10, which is not originally reported. According to REACH Guidance document chapter R.10 Table R.10-1 (Overview of toxicity test endpoints and guidance on derivation of L(E)C50 and NOEC values) an EC10 for a long-term test which is obtained using an appropriate statistical method (usually regression analysis) will be used preferentially.

There has been a recommendation within OECD in 1996 to phase out the use of the NOEC, in particular as it can correspond to large and potentially biologically important magnitudes of effect. The advantage of regression method for the estimation of ECx is that information from the whole concentration-effect relationship is taken into account and that confidence intervals can be calculated. These methods result in an ECx, where x is a low effect percentile (e.g. 5-20%). It makes results from different experiments more comparable than NOECs. 


The 72-h ErC50 was 600.5 mg/L (nominal). The 72-h ErC10 was determined to be 92.6 mg/L (nominal). These values were selected as key data.