Boron doped barium europium strontium silicate, orthorombic

Endpoint summary

Description of key information

Read Across Information is available from a structural analogue that has been tested in a GLP compliant OECD TG 423 assay. The LD50 in rats after single oral administration exceeds 2000 mg/kg bw/day.

Key value for chemical safety assessment

Acute toxicity: via oral route

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed

Dose descriptor:

LD50

Value:

2 000 mg/kg bw

Acute toxicity: via inhalation route

Endpoint conclusion

Endpoint conclusion:

no study available

Acute toxicity: via dermal route

Endpoint conclusion

Endpoint conclusion:

no study available

Additional information

Read Across Justification - Acute Oral Toxicity for Art. 132039 (RGA 565 100)

Type of Read Across: one - to -one

Chemical Similarity

The Dossier Compound, Boron doped barium europium strontium silicate, shows a data gap for Acute Oral Toxicity. However, information for this endpoint is available for the structural analogue, Barium europium strontium silicate.
Both compounds share the same silicate core structure and differ only in the Boron present in small amounts in the silicate of the target molecule with the data gap. There are no additional structural features of toxicological concern introduced in the traget molecule that are not present in the source molecule yet. Overall the high chemical similarity supports the read across from the target to the query molecule.

Physicochemical Similarity

The solubility of both compounds has been determined by measuring the concentration of the individual cations present in the silicate by means of ICP OES of the water extracts. It turned out that cationic ingredients like barium and strontium dissolve in water. They are moderately soluble. The cationic ingredient europium is not soluble in water. This result is confirmed by several supporting studies. Comparing the solubility profile yields a high similarity regarding the different cations.

Compound	Study	Ba	Sr	Eu
Ba Eu Sr SiO4	Key	0,24	0,8	0,038
Ba Eu Sr SiO4	Supp.001	0,54	0,6	0,07
Ba Eu Sr SiO4	Supp.002	0,87	0,49	0,12
(B) Ba Eu Sr SiO4	Key.001	0,528	0,488	0,05
(B) Ba Eu Sr SiO4	Supp.005	0,38	0,47	0,05
(B) Ba Eu Sr SiO4	Supp.003	0,287	0,524	0,05
(B) Ba Eu Sr SiO4	Supp.004	0,829	0,411	0,05

Table 1:Analytical concentrations of the different cations as determined by ICP OES measurements in [g/L]

The boron containing silicate yields an additional small fraction of boron of 6.6 mg/L (cf. water solubility, Sup_Water solubility_132008.003).
The pH of compounds is in the same range, i.e. 11-11.5.

Overall the relevant physicochemical data water solobility and pH show a high similarity supporting the read across from the target to the query molecule.

Biological similarity

Both compounds have been characterized for skin irritation in vitro in GLP compliant assays following the OECD TG 439 protocol employing the Reconstructed Human Epidermis Test by measuring cell-viabilities of cultivated human keratinocytes after topical application of test or control substance in a MTT assay. In this assay both compounds have been evaluated to be negative.

Read Across

The acute toxicity assay in the rat after single oral administration performed for the structural analogue, Barium europium strontium silicate, shows that the oral LD50 value in rats exceeds 2000 mg/kg bw/d.
This information is used for read across from the source molecule to the target molecule in order fill the data gap for acute oral toxicity. This read across is based on the high structural similarity, the absence of additional structural alerts in the target molecule, the almost identical physicochemical parameters relevant for exposure in biological tests and the absence of local irritation in skin models.

The high similarity demonstrated for chemical structure, physicochemical properties and biological response justifies using the information available for the source molecule to fill the data gap of the target molecule.

Justification for classification or non-classification

no need for classification, as LD 50 > 2000 mg/kg bw /d