Registration Dossier

Administrative data

Endpoint:
in vivo mammalian cell study: DNA damage and/or repair
Type of information:
experimental study planned (based on read-across)
Study period:
Following ECHA approval
Justification for type of information:
TESTING PROPOSAL ON VERTEBRATE ANIMALS – genetic toxicity in vivo

NON-CONFIDENTIAL NAME OF SUBSTANCE: dipotassium hexachloroplatinate(IV)
- Name of the substance on which testing is proposed to be carried out: diammonium hexachloroplatinate(IV)
- Name of the substance for which the testing proposal will be used [if different from tested substance]: dipotassium hexachloroplatinate(IV) [CAS RN 16921-30-5; EC No. 240-979-3]. The registrants note that, in line with the read-across justification included in this registration dossier, the data generated from the proposed test on diammonium hexachloroplatinate(IV) will be used in the dossiers of three hexachloroplatinate(IV) substances: diammonium hexachloroplatinate(IV) (substance-specific) [CAS RN 16919-58-7; EC No. 240-973-0], dipotassium hexachloroplatinate(IV) (this dossier) [CAS RN 16921-30-5; EC No. 240-979-3] and dihydrogen hexachloroplatinate(IV) (hexachloroplatinic acid; CAS RN 16941-12-1; EC No. 241-010-7].

CONSIDERATIONS THAT THE GENERAL ADAPTATION POSSIBILITIES OF ANNEX XI OF THE REACH REGULATION ARE NOT ADEQUATE TO GENERATE THE NECESSARY INFORMATION [please address all points below]:
- List of all substance-specific available GLP and non-GLP studies considered for this test proposal:
Bunger et al. (1996). Ames test; Similar to OECD guideline 471; GLP not specified; positive with and without metabolic activation.
Suraikina et al. (1979). Ames test; No guideline followed; GLP not specified; weak positive without metabolic activation.
Taylor et al. (1979). Mammalian cell gene mutation assay; Similar to OECD guideline 476; GLP not specified; weak positive without metabolic activation.
Gebel et al. (1997). Mammalian cell micronucleus assay; Similar to OECD guideline 487; GLP not specified; negative without metabolic activation.
Gebel et al. (1997). SOS chromotest; No guideline followed; GLP not specified; negative without metabolic activation.
Lantzsch and Gebel (1997). SOS chromotest; No guideline followed; GLP not specified; negative without metabolic activation.
No substance-specific in vivo genotoxicity studies were identified.
- Historical human data: No substance-specific data identified.
- (Q)SAR: It is acknowledged that the results of QSAR modelling are of very limited applicability for inorganic substances (e.g. metals) and organometallics.
- In vitro methods: The available in vitro methods have been considered as part of the tiered approach to testing (see “List of substance-specific available GLP and non-GLP studies considered for this test proposal” [above] and “Grouping and read-across” [below] for details).
- Grouping and read-across: Dipotassium hexachloroplatinate(IV) is considered to fall within the scope of the read-across category “hexachloroplatinate(IV) substances”. Data on two additional members of this category, diammonium hexachloroplatinate(IV) and hexachloroplatinic acid, were also considered in order to supplement the dataset for dipotassium hexachloroplatinate(IV). No in vivo genotoxicity data were identified for these substances. The read-across studies, considered for this test proposal, are listed below:

Diammonium hexachloroplatinate(IV) [CAS RN 16919-58-7; EC No. 240-973-0]
Bunger et al. (1996). Ames test; Similar to OECD guideline 471; GLP not specified; positive with and without metabolic activation.
Bootman and May (1980). Ames test; Similar to OECD guideline 471; GLP not specified; ambiguous with metabolic activation, negative without metabolic activation.
Kanematsu et al. (1980). Ames spot test; No guideline followed; GLP not specified; positive without metabolic activation.
Kanematsu et al. (1980). Rec assay; No guideline followed; GLP not specified; positive without metabolic activation.
Migliore et al. (1999). Mammalian cell micronucleus assay; No guideline followed; GLP not specified; positive (metabolic activation not specified).

Hexachloroplatinic acid [CAS RN 16941-12-1; EC No. 241-010-7]
Scarcella (2004). Ames test; According to OECD guideline 471; GLP compliant; positive with and without metabolic activation.
Verspeek-Rip (2002). Ames test; According to OECD guideline 471; GLP compliant; equivocal result in one strain (negative in all other strains) with and without metabolic activation.
Uno and Morita (1993). Ames test; No guideline followed; GLP not specified; weak positive with and without metabolic activation.
Kanematsu et al. (1980). Ames spot test; No guideline followed; GLP not specified; negative without metabolic activation.
Kanematsu et al. (1980). Rec assay; No guideline followed; GLP not specified; positive without metabolic activation.
Verspeek-Rip (2003). Mammalian cell gene mutation assay; According to OECD guideline 476; GLP compliant; positive with and without metabolic activation.

- Weight of evidence (summary of key data): Dipotassium hexachloroplatinate(IV) was assessed in a bacterial reverse mutation (Ames) assay using four Salmonella typhimurium strains (TA97a, TA98, TA100 and TA102), in both the presence and absence of metabolic activation (S9). Mutagenic activity was observed in this Ames assay. Further, dipotassium hexachloroplatinate(IV) was weakly mutagenic when tested up to cytotoxic concentrations in CHO cells without S9. The compound did not induce micronuclei in human lymphocytes, indicating a lack of a genotoxic (clastogenic) effect. However, in the light of the lack of toxicity at any of the concentrations scored for micronuclei (and only tested in the absence of S9), these negative results should be viewed with caution. No in vivo genotoxicity studies were identified for any hexachloroplatinate(IV) substances.

CONSIDERATIONS THAT THE SPECIFIC ADAPTATION POSSIBILITIES OF ANNEXES VI TO X (AND COLUMN 2 THEREOF) OF THE REACH REGULATION ARE NOT ADEQUATE TO GENERATE THE NECESSARY INFORMATION:
- The substance is not classified for carcinogenicity or mutagenicity therefore genetic toxicity testing cannot be waived. As outlined in the Integrated Testing Strategy (ITS) for mutagenicity (ECHA, 2017), “if there is a positive result in any of the in vitro studies from Annex VII or VIII and there are no appropriate results available from an in vivo study already, an appropriate in vivo somatic cell genotoxicity study should be proposed.” No in vivo genotoxicity data were identified for this substance, or indeed any of the “hexachloroplatinate(IV) substances” category members. Moreover, there are no adaptations for in vivo somatic cell genotoxicity testing according to Column 2 of the REACH Annexes on information requirements (EC, 2014). Hence, the observation of mutagenic activity in both bacteria and mammalian cells necessitates the consideration of further in vivo testing “as a last resort” (ECHA, 2016).

FURTHER INFORMATION ON TESTING PROPOSAL IN ADDITION TO INFORMATION PROVIDED IN THE MATERIALS AND METHODS SECTION:
- Details on study design / methodology proposed: In order to assess the potential to induce genotoxicity in vivo, an alkaline comet assay (OECD Test Guideline 489), with a concomitant micronucleus assay and combined toxicokinetic assessment is proposed. The purpose of the comet assay is to identify substances that cause DNA damage, by detecting single and double stranded breaks. “These strand breaks may be repaired, resulting in no persistent effect, may be lethal to the cell, or may be fixed into a mutation resulting in a permanent viable change. They may also lead to chromosomal damage which is also associated with many human diseases including cancer” (OECD, 2016). In the Comet assay, it is proposed that somatic cells are sampled from three tissues: the liver (systemically exposed tissue) and the glandular stomach and duodenum (site-of contact tissues). The duodenum tissue will be stored/frozen, and only analysed (Comet measurements taken) if both the liver and glandular stomach provide a negative response. Germ cells will also be collected at the same time, stored/frozen, and Comet measurements taken if either the liver or glandular stomach provide a positive response. It is proposed to conduct this study in rats following oral gavage dosing. Bone marrow is selected as the target tissue for micronuclei assessment. Inclusion of a parallel toxicokinetic study is proposed for the purpose of demonstrating that adequate target tissue exposure to the test substance has been achieved.
It is proposed to test diammonium hexachloroplatinate(IV) in rats by the oral route, with the results being applied for read-across to the other two compounds in this category, namely dipotassium hexachloroplatinate(IV) (this dossier) [CAS RN 16921-30-5; EC No. 240-979-3] and hexachloroplatinic acid [CAS RN 16941-12-1; EC No. 241-010-7]. See section 13 in IUCLID for full read-across justification report.

References:
ECHA (2016). European Chemicals Agency. How to prepare registration and PPORD dossiers. Version 1.0. April 2016. https://echa.europa.eu/documents/10162/22308542/manual_regis_and_ppord_en.pdf

ECHA (2017). European Chemicals Agency. Guidance on Information Requirements and Chemical Safety Assessment. Chapter R.7a: Endpoint specific guidance. Version 6.0. July 2017. https://echa.europa.eu/documents/10162/13632/information_requirements_r7a_en.pdf

EC (2014). European Commission. C1 Regulation (EC) No 1907/2006 of the European parliament and of the council of 18 December 2006 concerning the Registration, Evaluation, Authorisation and Restriction of Chemicals (REACH), establishing a European Chemicals Agency, amending Directive 1999/45/EC and repealing Council Regulation (EEC) No 793/93 and Commission Regulation (EC) No 1488/94 as well as Council Directive 76/769/EEC and Commission Directives 91. http://eur-lex.europa.eu/legal-content/EN/TXT/PDF/?uri=CELEX:02006R1907-20140822

OECD (2016). Organisation for Economic Cooperation and Development. OECD guideline for the testing of chemicals. In Vivo Mammalian Alkaline Comet Assay. TG 489. Adopted: 29 July 2016. http://www.oecd-ilibrary.org/docserver/download/9716431e.pdf?expires=1475142425&id=id&accname=guest&checksum=151E9EE218B896F623F1DAE23EB3667F

Data source

Materials and methods

Test guideline
Qualifier:
according to
Guideline:
OECD Guideline 489 (In vivo Mammalian Alkaline Comet Assay)
Deviations:
no
GLP compliance:
yes
Type of assay:
mammalian comet assay

Test material

Reference
Name:
Unnamed
Type:
Constituent

Results and discussion

Applicant's summary and conclusion