Tris[(2-hydroxyethyl)ammonium] citrate

Short-term toxicity to fish

Description of key information

The 48-h LC50 value for citric acid in fish (golden orfe) is 440 mg/L, the 96-h LC50 value for monoethanolamine is 349 mg/L. After correction for molecular weight the effect concentrations for tris[(2-hydroxyethyl)ammonium] citrate are 860 and 2142 mg/L, respectively. The lowest value of 860 mg/L will be used in the assessment.

Key value for chemical safety assessment

Fresh water fish

Fresh water fish

Effect concentration:

860 mg/L

Additional information

Short-term studies with fish are not available for tris[(2-hydroxyethyl)ammonium] citrate. Tris[(2-hydroxyethyl)ammonium] citrate is the neutral salt of monoethanolamine and citric acid. Monoethanolamine and citric acid are the starting materials for the synthesis of tris[(2-hydroxyethyl)ammonium] citrate, and the only difference is that in tris[(2-hydroxyethyl)ammonium] citrate the substances are present in their ionic forms as a monoethanolamine cation and a citrate anion. It is expected that the ecotoxicological properties of tris[(2-hydroxyethyl)ammonium] citrate shall be governed by the properties of monoethanolamine and citric acid (for more details see reporting format for the analogue approach in Appendix A.2).

For monoethanolamine a GLP-compliant Directive 92/69/EEC, C.1. guideline study with carp (Cyprinus carpio) is available (Huels, 1997b). Fish (10/dose) were exposed to nominal concentrations of 3 to 1,000 mg/L under semi-static conditions for 96 hours, the test concentrations were analytically verified and were within 80% of nominal concentrations. None of the controls or fish exposed to 90 mg/L died. One fish exposed to 150 mg/L died between 72 and 96 hours. Two fish exposed to 280 mg/L died within 72 hours. All fish exposed to 500 and 900 mg/L were dead by 48 and 24 hours, respectively. A 96-h LC50 value 349 mg/L is reported. A safety factor need not to be applied to this value. Instead, the effect concentration is corrected for molecular weight which leads to an effect concentration of 2142 mg/L for tris[(2-hydroxyethyl)ammonium] citrate.

For citric acid a non-GLP study is available for golden orfe (Leucidus idus melanotus) which was performed in a method equivalent to OECD guideline 203 (Juhnke and Lüdemann, 1978). In this study, fish (10/dose) were exposed to citric acid in a static system. Little further information on test conditions and design is available. A 48-h LC50 value of 440 mg/L is reported. A safety factor need not to be applied to this value. Instead, the effect concentration is corrected for molecular weight which leads to an effect concentration for tris[(2-hydroxyethyl)ammonium] citrate of 860 mg/L.

The lowest effect concentration of 860 mg/L will be used in the assessment.