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Ecotoxicological information

Toxicity to aquatic algae and cyanobacteria

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Description of key information

Acutely toxic to aquatic algae.

Key value for chemical safety assessment

EC50 for freshwater algae:
28 mg/L
EC50 for marine water algae:
9 mg/L
EC10 or NOEC for freshwater algae:
10 mg/L

Additional information

The toxicity of morpholine to aquatic freshwater algae was tested according to the EPA, National Eutrophication Research Program (US Environmental Protection Agency, Corvallis, Oreg., 1971; as proposed by Chiaudani & Vighi). In this 96-h growth inhibition test, using Pseudokirchneriella subcapitata as test organism, a 96-h ErC50 of 28 mg/L and a NOErC of 10 mg/L were determined based on nominal, analytically verified test concentrations (not pH-adjusted), indicating that morpholine is acutely harmful to aquatic freshwater algae.


This indication for freshwater algae is supported by several test results as summarized in the following table:


Test Species

Duration / Dose Descriptor

Effect Concentration [mg/L]


NITE (1997)

Pseudokirchneriella subcapitata

72-h ErC10


nominal, unbuffered; recalculated with Toxrat v3.2.1

72-h ErC50


Adams et al. (1985)

Pseudokirchneriella subcapitata

96-h NOErC


nominal, pH unspecified

Millington et al. (1988)

Pseudokirchneriella subcapitata

96-h LOEC


Based on: area under growth curve; OECD – medium; nominal, pH unspecified

Desmodesmus subspicatus

96-h LOEC


Chlorella vulgaris

96-h LOEC



However, Eide-Haugmo et al. (2012/2009) performed a guideline study according to ISO 10253 with the marine algae Skeletonema costatum. After 72 hours an ErC50 of 9.0 mg/L was determined representing the lowest available 72-h ErC50 value for aquatic algae.


Summing up the available experimental data, morpholine is assessed to be acutely toxic to aquatic algae and cyanobacteria, based on the marine data on Skeletonema costatum.