Strontium 4-[(5-chloro-4-methyl-2-sulphonatophenyl)azo]-3-hydroxy-2-naphthoate (1:1)

Endpoint summary

Key value for chemical safety assessment

Genetic toxicity in vitro

Description of key information

Pigment Red 48:3(Sr) is not genotoxic in vitro based on experimental data of pigments of the same category.

Link to relevant study records

Reference

Reference 1

Endpoint:

in vitro gene mutation study in bacteria

Type of information:

read-across based on grouping of substances (category approach)

Adequacy of study:

key study

Justification for type of information:

Please see the category read-across justification in the category object.

Reason / purpose for cross-reference:

read-across source

Reason / purpose for cross-reference:

read-across source

Reason / purpose for cross-reference:

read-across source

Species / strain:

S. typhimurium TA 1535

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

not specified

Species / strain:

S. typhimurium TA 1537

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

not specified

Species / strain:

S. typhimurium TA 98

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

not specified

Species / strain:

S. typhimurium TA 100

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

not specified

Species / strain:

E. coli WP2 uvr A

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

not specified

Species / strain:

E. coli WP2 uvr A pKM 101

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

not specified

Reference 2

Endpoint:

in vitro cytogenicity / chromosome aberration study in mammalian cells

Type of information:

read-across based on grouping of substances (category approach)

Adequacy of study:

key study

Justification for type of information:

Please see the category read-across justification in the category object.

Reason / purpose for cross-reference:

read-across source

Reason / purpose for cross-reference:

read-across source

Reason / purpose for cross-reference:

read-across source

Species / strain:

Chinese hamster lung (CHL/IU)

Metabolic activation:

with and without

Genotoxicity:

other: poliploidy positive at precipitaton

Cytotoxicity / choice of top concentrations:

not specified

Species / strain:

Chinese hamster lung (CHL/IU)

Metabolic activation:

with and without

Genotoxicity:

other: clastogenicity negative

Cytotoxicity / choice of top concentrations:

not specified

Species / strain:

Chinese hamster lung fibroblasts (V79)

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

not specified

Reference 3

Endpoint:

in vitro gene mutation study in mammalian cells

Type of information:

read-across based on grouping of substances (category approach)

Adequacy of study:

key study

Justification for type of information:

Please see the category read-across justification in the category object.

Reason / purpose for cross-reference:

read-across source

Reason / purpose for cross-reference:

read-across source

Species / strain:

Chinese hamster lung fibroblasts (V79)

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

not specified

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (negative)

Genetic toxicity in vivo

Endpoint conclusion

Endpoint conclusion:

no study available

Additional information

No data on Pigment Red 48:3(Sr) was available. Detailed experimental data is available for the analogue calcium salt Pigment Red 48:2(Ca), which is also poorly soluble, but of slightly better solubility than Pigment Red 48:3(Sr). To assess, the genetic toxicity of the strontium, detailed experimental data is used from Pigment Red 57(Sr).

In vitro mutagenicity in bacteria

The mutagenicity of Pigment Red 48:2(Ca) in vitro was assessed in two tests applying both the standard assay with rat liver homogenate and the modified assay for azo compounds (Prival-assay). Tested samples were commercial products containing varying amounts of additives. With the limitation in the number of tester strains, the non-key study is reliable and valid in regard to design, positive and negative control and concentrations. The key study was performed following the latest OECD testing guideline (OECD 471, adopted July 12, 1997) and the principles of GLP and included the Prival assay modification to take into account reductive metabolism of the azo bond.

For Pigment Red 57(Sr), the mutagenicity in vitro was assessed in two tests applying both the standard assay with rat liver homogenate and the modified assay for azo compounds (Prival-assay). The studies were performed following the latest OECD testing guideline (OECD 471) and the principles of GLP. The standard test was performed with doses of 7.88, 19.5, 39.1, 78.1, 156 and 313 μg/plate using the pre-incubation method and DMSO as vehicle, and included all five tester strains (DIC 2005a). The assay with the Prival modification was performed with Salmonella typhimurium TA 1535, TA 100, TA 1537, TA 98 and doses of 0, 20, 100, 500, 2500 and 5000 μg/plate in DMSO were applied (BASF AG 1992).

In vitro mutagenicity in mammalian cells

Mutagenicity in mammalian cells in vitro was investigated with Pigment Red 48:2(Ca) in a hprt test following OECD testing guideline 476 (adopted July 21, 1997) and the principles of GLP. No indication of a mutagenic effect was observed at concentrations up to 1000 µg/plate, the two highest concentrations being in the precipitating range. This is consistent with the absence of unscheduled DNA synthesis of the calcium analogue as tested with both with human fibroblasts (Meyer 1987) and with primary hepatocytes prepared from arochlor1254-induced rats (Hertner 1987). The latter studies were performed under GLP and in combination fulfil the requirements of OECD testing guideline 482 (adopted October 23, 19869. For the DNA-repair assays, concentrations were in similar range and also resulted in precipitation. Higher concentrations were too toxic for scoring. For all three studies, commercial samples of known composition were tested.

In vitro clastogenicity in mammalian cells

For clastogenicity in vitro, experimental data from studies with samples of Pigment Red 48:2(Ca) and 57(Sr) is taken into account.

Clastogenicity of Pigment Red 48:2(Ca) in mammalian cells was investigated in a guideline (OECD 473. adopted July 21, 1997) and GLP compliant study (Höpker 2007). The test was performed with a sample synthesized without additives and a purity of 99.4%. The highest evaluable concentrations were chosen based on visual observation of precipitates. No indication of clastogenicity or polyploidy were observed in either study.

For Pigment Red 57(Sr), clastogenicity in mammalian cells was investigated in a guideline (OECD 473. adopted July 21, 1997) and GLP compliant study (DIC 2005). Purity of the test sample is adequate. Pigment Red 57(Sr) was applied as a suspension in 0.5% carboxymethylcellulose in water. Precipitation of the test item was observed at all concentrations at the start and at the beginning of the incubation and the test item coloured the culture medium red. In the range-finding test concentrations as low as 18.5 μg/mL caused precipitation as well as culture medium colouration. For the main study, the highest dose was chosen based on a reduction in growth rate by less than 50%, and so all doses were in the precipitating range. A dose-dependent increase in numerical aberrations occurred in the absence and presence of S9 mix after 6h and 24h treatment in parallel to cytotoxicity. This increase was above the historical control range and could not be attributed to a change in pH. Changes in osmolality also cause chromosome breaks in cell culture studies, but osmolality was not measured in this study. After 24h treatment, the incidence of numerical aberrations was 17, 21 and 26 % at 39.5, 59.3 and 88.9 μg/mL, respectively. Higher concentrations could not be scored because the precipitates were too numerous. In the presence of S9 mix after 6h treatment, the incidence was 5.5, 11 and 14% at 150, 300 and 600 μg/mL, respectively. In the absence of S9 mix after 6h treatment, the incidence was 16.5, 18.5 and 34% at 75, 150 and 300 μg/mL, respectively. As cultured cells are sensitive to mechanical effects of precipitates and no doses in the non-precipitating range were tested, the relevance of the increase in polyploidy index is questionable. A concomitant increase in cytotoxicity and polyploidy index indicates that the actual pigment component is very unlikely to be the cause.

Justification for classification or non-classification

The available experimental test data are reliable and suitable for classification purposes under Regulation 1272/2008. As a result the substance is not considered to be classified for genetic toxicity according to Classification, Labelling, and Packaging Regulation (EC) No. 1272/2008.