Registration Dossier

Ecotoxicological information

Endpoint summary

Administrative data

Description of key information

Additional information

The registered substance (CAS # 20566-35-2) involves the heating and subsequent reaction of Tetrabromophthalic Anhydride (TBPA) with Di-Ethylene Glycol (DEG) and Propylene Oxide (PO). The nature of the reagents involves the formation of a complex mixture of products with different combinations of these 3 reagents. Therefore, the substance has been flagged as UVCB substance.

Most of the aquatic toxicity data of the registrered substance are based on QSAR model. However, current QSAR models cannot test UVCB substances. Therefore, the QSAR has been performed on the major product which is also the structure with the lowest molecular weight (1 unit of region of TBPA, 1 DEG and 1 PO). In terms of predicted toxicology, it can reasonably be assumed that the structure having the lowest molecular weight should be the most bioavailable for living organisms. Based on this toxicity principle, QSAR analyses were performed using the SMILE structure of the smallest molecular weight structure which is also the major product of the mixture (identified at 26% area by HPLC).

As an overall observation, the aquatic toxicity is systematically above the predicted solubility of the structure ran in the QSAR model. Therefore, it can be concluded that the toxicity toward aquatic organisms maybe unexpected. Going further in the analyses, several stuctures of the UVCB substance having differents combinations of TBPA, DEG and PO have been tested using the QSAR tool (cfr attachement for results). Based on the analysis, it can be concluded that more the structure has an increase moledular weight, more the strcture become less soluble with an higher logKow. These results reinforce the strategy to base our data on the structure with the lowest moleculare weight.