Morpholine

Short-term toxicity to fish

Description of key information

With high probability acutely not harmful to fish.

Key value for chemical safety assessment

LC50 for freshwater fish:

180 mg/L

LC50 for marine water fish:

179 mg/L

Additional information

The assessment of the short-term toxicity to fish is based on the available data from studies with several freshwater and saltwater species:

The selected key studies (Calamari et al., 1980) for freshwater fish were performed according to IRSA (1980) with Oncorhynchus mykiss in soft and in hard water. The test concentrations were analytically verified. The resulting 96-h LC50 values were 180 mg/L (nominal) for soft water and 380 mg/L (nominal) for hard water, respectively.

The key data are supported by the results of several freshwater and marine studies as summarized in the following table:

Reference	Guideline	Test Species	Duration / Dose Descriptor	Effect Concentration [mg/L]	Remarks
NITE (1997)	OECD 203	Oryzias latipes	96-h LC50	> 100	nominal; analytically verified; limit test
	OECD 204		14-d LC50	> 92	measured
Dawson et al. (1977)	No guideline specified*	Lepomis macrochirus	96-h LC50	350	nominal
		Menidia beryllina (marine species)	96-h LC50	400	nominal
Wellens H. (1982)	UBA, Document I 5.3-97125-2/6	Danio rerio	96-h LC50	> 1000	nominal
McCain & Peck (1976)	APHA (1965)**	Vala mugil engeli (marine species)	96-h LC50	179	nominal; geometric mean of LC0 and LC100***
		Gambusia affinis (marine species)	96-h LC50	423	nominal; geometric mean of LC0 and LC100***
		Tilapia sp. (marine species)	96-h LC0	>1000	nominal; only LC0 reported

*Study meets generally accepted scientific principles, acceptable for assessment.

**American Public Health Association (1965). Standard Methods for the Examination of Water and Wastewater, 12th ed. New York, USA.

*** The calculation of the LC50 is not done in a proper way since the geometric mean between LC0 and LC100 was used. This is only correct if there is no effective concentration between LC0 and LC100. In this case, there is a concentration in between.

The stability of morpholine (CAS 110-91-8) in the test medium has not been analytically confirmed in all supporting studies, but is considered to be stable due to the high water solubility (completely miscible), the moderate vapour pressure (VP = 9.8 hPa, at 20 °C) and the low Henry´s law constant (HLC, uncharged: 0.0115 Pa*m3/mol, at 25 °C) of the substance.

 

Conclusion:

Summing up the available freshwater and saltwater data, morpholine is assessed to be with high probability not acutely harmful to fish.