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Key value for chemical safety assessment

Additional information

With triple superphosphate an Ames test and a chromosome aberration study is present. A reliable TK-assay is not available with the substance itself. The assessment of gene mutation in mammalian cells was therefore based on a study conducted with a reference substance as part of a read-across approach, which is in accordance with Regulation (EC) No. 1907/2006, Annex XI, 1.5. Structural similarities and similarities in properties and/or activities of the source and target substance are the basis of read-across. A detailed justification for the read-across approach is provided in the technical dossier (see IUCLID Section 13) and within Chapter 5.1 of the CSR.

In an Ames test according to OECD 471 guideline, Salmonella Typhimurium strains TA 98, TA 100, TA 1535 and TA 1537 and E. Coli WP2 uvr A showed no genotoxicity with and without metabolic activation, showing cytotoxicity at the highest concentrations tested. In an in-vitro chromosome aberration test with CHO cells performed according to OECD 473 guideline, also no genotoxicity was seen with and without metabolic activation. With ammonium dihydrogenorthophosphate a reliable TK-assay was present. In a Thymidine kinase (TK) assay in L5178Y mouse lymphoma cells performed according to OECD 476 and EC B.17 guidelines, the substance did not induce a significant increase in the mutation frequency. Based on these negative results for genotoxicity in in vitro studies, no in-vivo studies are necessary.

Justification for selection of genetic toxicity endpoint

No study was selected, since all available in-vitro genetic toxicity studies were negative. Hazard assessment is also conducted by means of read-across. The available study with the reference substance is adequate and reliable based on the identified similarities in structure and intrinsic properties between source and target substance and overall quality assessment (refer to the endpoint discussion for further details).

Short description of key information:

Based on reliable in-vitro studies with triple superphosphate, the Ames test and the chromosome aberration study were negative in the presence and absence of metabolic activation. No reliable study for the TK assay was present with triple superphosphate, however a reliable in-vitro TK assay with ammonium dihydrogenorthophosphate is present showing negative results in the presence and absence of metabolic activation.

Endpoint Conclusion: No adverse effect observed (negative)

Justification for classification or non-classification

Based on the available data, triple superphosphate does not have to be classified according to Directive 67/548/EC and the CLP Regulation for genetic toxicity.

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