Tris[(2-hydroxyethyl)ammonium] citrate

Ecotoxicological Summary

Hazard for aquatic organisms

Freshwater

Hazard assessment conclusion:

PNEC aqua (freshwater)

PNEC value:

522 µg/L

Assessment factor:

10

Extrapolation method:

assessment factor

PNEC freshwater (intermittent releases):

154 µg/L

Marine water

Hazard assessment conclusion:

PNEC aqua (marine water)

PNEC value:

52.2 µg/L

Assessment factor:

100

Extrapolation method:

assessment factor

STP

Hazard assessment conclusion:

PNEC STP

PNEC value:

615 mg/L

Assessment factor:

10

Extrapolation method:

assessment factor

Sediment (freshwater)

Hazard assessment conclusion:

PNEC sediment (freshwater)

PNEC value:

2.4 mg/kg sediment dw

Extrapolation method:

equilibrium partitioning method

Sediment (marine water)

Hazard assessment conclusion:

PNEC sediment (marine water)

PNEC value:

0.24 mg/kg sediment dw

Extrapolation method:

equilibrium partitioning method

Hazard for terrestrial organisms

Soil

Hazard assessment conclusion:

PNEC soil

PNEC value:

0.174 mg/kg soil dw

Extrapolation method:

equilibrium partitioning method

Additional information

No substance-specific data are available for tris[(2-hydroxyethyl)ammonium] citrate, however read-across from monoethanolamine and citric acid is used for the assessment to meet the majority of the standard REACH information requirements. 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 detailssee reporting format for the analogue approach in Appendix A.2).

There is a complete set of data available for monoethanolamine. Besides short-term tests on fish, invertebrates and algae also long-term studies are available.For citric acid the base set data are available, including a microorganism toxicity study.

Guideline studies for short-term toxicity are available for freshwater fish. The critical acute effect concentration for monoethanolamine is a 96-h LC50 value of 349 mg/L in carp (Cyprinus carpio) (Huels, 1997a), the critical effect concentration for citric acid is a 48-h LC50 value of 440 mg/L in golden orfe (Leuciscus idus melanotus) (Juhnke and Lüdemann, 1978). For monoethanolamine a guideline study for long-term toxicity is available, the critical chronic effect concentration is a 30-d NOEC of 1.2 mg/L in Japanese killifish (Oryzias latipes) (NITE, 2006).After correction for molecular weight, the effect concentrations for tris[(2-hydroxyethyl)ammonium] citrate of 860 mg/L for short-term toxicity and 7.37 mg/L for long-term toxicity in fish will be used in the assessment.

For invertebrates short-term toxicity guideline studies are available for Daphnia magna. The critical effect concentrations for monoethanolamine is a 48-h EC50 value of 65 mg/L (Huels, 1997b), the critical effect concentration for citric acid is a 24-h EC50 value of 1,535 mg/L (Bringmann and Kühn, 1982). For monoethanolamine a guideline study for long-term toxicity is available, the critical chronic effect concentration is a 21-d NOEC 0.85 mg/L (NITE, 1996a).After correction for molecular weight, the effect concentrations for tris[(2-hydroxyethyl)ammonium] citrate of 399 mg/L for short-term toxicity and 5.22 mg/L for long-term toxicity in daphnids will be used in the assessment.

A growth inhibition guideline study is available for freshwater algae. The critical effect concentrations for monoethanolamine are a 72-h EC50 value of 2.5 mg/L and a 72-h NOEC of 1 mg/L in Pseudokirchneriella subcapitata (NITE, 1996b), the critical effect concentration for citric acid is a 8-d toxicity threshold (which is equivalent to an EC3) value of 640 mg/L in Scenedesmus quadricauda (Bringmann and Kuhn, 1977).After correction for molecular weight, the effect concentrations for tris[(2-hydroxyethyl)ammonium] citrate of 15.4 mg/L for short-term toxicity and 6.15 mg/L for long-term toxicity in algae will be used in the assessment.

For the toxicity of microorganisms a respiration inhibition guideline study with domestic activated sludge is available (BASF, 1991) for monoethanolamine. The 30-min EC10 is >1,000 mg/L. For citric acid a growth inhibition test with Pseudomonas putida is available, the 16-h toxicity threshold (which is equivalent to an EC3) is >10,000 mg/L.After correction for molecular weight, an effect concentration for tris[(2-hydroxyethyl)ammonium] citrate of >6,146 mg/L for STP microorganism toxicity will be used in the assessment.

Studies with terrestrial organisms are not available. Because the calculated log Kow for tris[(2-hydroxyethyl)ammonium] citrate is low (-3.52), it is expected that tris[(2-hydroxyethyl)ammonium] citrate will mainly partition to the water compartment. Therefore, direct and indirect exposure of the terrestrial compartment is not expected.

Conclusion on classification

Based on Directive 67/548/EEC, results of validated structure activity relationships and expert judgment may also be taken into account where appropriate with regard to classification and labelling of substances.

Based on all available data for daphnids, fish and algae, tris[(2-hydroxyethyl)ammonium] citrate need not to be classified according to Directive 67/548/EEC nor for EU Classification, Labelling and Packaging of Substances and Mixtures (CLP) Regulation (EC) No. 1272/2008.