Calcium glycinate (1:2)

Short-term toxicity to fish

Link to relevant study record(s)

Reference

Endpoint:

short-term toxicity to fish

Type of information:

(Q)SAR

Adequacy of study:

key study

Study period:

2019

Reliability:

1 (reliable without restriction)

Justification for type of information:

The fish acute toxicity test provides information on the acute toxicity of chemicals for environmental hazards and risk assessment.
The aim was to estimate the fish acute toxicity of target substance.
2.1.1 Estimation of the biological activity (fish acute toxicity)
The computational simulation was performed based on the read-across approach. The readacross is one of the so-called alternative test methods recommended by REACH, where the predictions are based on the experimental data available for the most similar compounds. The predictions were performed according to the Read-Across Assessment Framework (RAAF), which assumes six different risk assessment scenarios of chemical compounds.
Applied tool:
The OECD QSAR Toolbox, version 4.4
Procedure of analysis:
I. Profiling of the target substance in order to retrieve relevant information related to mechanism of action and observed or simulated metabolites
II. Simulation of the dissociation process determination of source compounds.
III. Data collection for the transformation products (OECD Toolbox database).
IV. Toxicity prediction for the target substance
V. Category consistency check in order to assess the quality of the prediction
Applied scenario:
Scenario 1
Toxicity prediction for the target substance:
This read-across is based on the fact that target compound undergoes dissociation reaction, it is expected that this will be one of the first reactions to which our target chemical is exposed.
Thus, the prediction is based on toxicological data of the dissociation products of the target chemical.
The target substance is an organometallic compound containing calcium (Ca) centres, glycine (Gly) ligands. The metallic centres of the substance are linked by oxygen coordination bonds of the Gly ligands. The weak bonds between metallic centres and the oxygen atoms in the compound structure break easily and favour rapid dissociation of the substance into its basic products (Ca(OH)2, Gly±). Glycine is an amino acid which is not considered as toxic compound.
Calcium (II) hydroxide would have similar dissociation products (Ca2+ and OH-)). Therefore, the prediction is based only on the Ca(OH)2.
The fish acute toxicity for the source compound was performed according to:
Test guideline: OECD 203
Endpoint: LC50
Test organism: Oncorhynchus mykiss
Duration: 96h
The read-across prediction of the fish acute toxicity for the target substance was performed based on the approach "one to one". The fish acute toxicity for the target substance was based on data for calcium hydroxide.

Principles of method if other than guideline:

In order to meet regulatory needs, reliability of the predicted results should be assessed. In case of classic quantitative structure-activity relationships (QSAR) modelling, this idea can be realised by analysing, whether the predicted value is located within so-called applicability domain. The applicability domain is a theoretical region, defined by the range of toxicity values and structural descriptors for the training compounds, where the predictions may be considered
as realistic ones. In a specific case of read-across, the internal consistency of the group of source compounds (called "category" in OECD Toolbox nomenclature, independently which approach: analogue approach or category approach is used). The category consistency check should be based on the parameters describing the structural similarity and/or properties as well
as mechanistic similarity of the tested compounds. For example, all members of the category (analogues as well as target substance) need to have the same functional groups and endpoint specific alerts.
In the case of read-across-based prediction of the fish acute toxicity of the calcium glycine (1:2) monohydrate), the category members are dissociation products of the target compound.
Selected physicochemical properties and ecotoxicological endpoint were analysed to assess the consistency of the category. Due to the chosen scenario, using experimental data of Ca(OH)2 for predicting biological activity for the target compound was justified in spite of differences in terms of substance type (inorganic) and inaccessibility of physicochemical data such as octanol-water partition coefficient.

Duration:

96 h

Dose descriptor:

LC50

Effect conc.:

50.6 mg/L

Nominal / measured:

nominal

Details on results:

The target compound undergoes a dissociation reaction into its basic products: Ca2+ and Gly±.
Ca(OH)2 as well as glycine are not considered as toxic. The toxicity prediction was performed based on the experimental data included in the OECD QSAR Toolbox. The fish acute toxicities for the dissociation products were as follow: > 1000 mg/L for glycine and 50.6 mg/L for calcium hydroxide. Considering the worst-case scenario, the prediction was based only on the experimental data for Ca(OH)2.

Validity criteria fulfilled:

yes

Conclusions:

The fish acute toxicity for the target substance is predicted at level LC50 = 50,6 mg/L.

Key value for chemical safety assessment

Fresh water fish

Fresh water fish

Effect concentration:

50.6 mg/L

Additional information

The fish acute toxicity for the target substance is predicted at level LC50 = 50.6 mg/L.