Strontium hydrogen phosphate

Endpoint summary

Key value for chemical safety assessment

Genetic toxicity in vitro

Description of key information

Weight of Evidence. Negative results were obtained with the test item in three K1 studies according to OECD 471, OECD 473 and OECD 476 (GLP studies).

Link to relevant study records

Reference

Reference 1

Endpoint:

in vitro gene mutation study in mammalian cells

Remarks:

Type of genotoxicity: gene mutation

Type of information:

experimental study

Adequacy of study:

key study

Study period:

22 April, 2014 - 02 June, 2014

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Remarks:

The study has been performed according to OECD and/or EC guidelines and according to GLP principles.

Qualifier:

according to guideline

Guideline:

OECD Guideline 476 (In Vitro Mammalian Cell Gene Mutation Test)

Version / remarks:

(1997)

Deviations:

no

Qualifier:

according to guideline

Guideline:

EU Method B.17 (Mutagenicity - In Vitro Mammalian Cell Gene Mutation Test)

Version / remarks:

(2008)

Deviations:

no

Principles of method if other than guideline:

The recommendations of the “International Workshop on Genotoxicity Tests Workgroup” (the IWGT), published in the literature (Clive et al., 1995, Moore et al., 1999, 2000, 2002, 2003, 2006 and 2007).

GLP compliance:

yes

Type of assay:

mammalian cell gene mutation assay

Target gene:

Thymidine kinase (TK) locus in L5178Y mouse lymphoma cells

Species / strain / cell type:

mouse lymphoma L5178Y cells

Details on mammalian cell type (if applicable):

- Type and identity of media:
- RPMI 1640 Hepes buffered medium (Dutch modification) containing penicillin/streptomycin (50 U/ml and 50 μg/ml, respectively), 1 mM sodium pyruvate and 2 mM L-glutamin supplemented with 10% (v/v) heat-inactivated horse serum (=R10 medium).
- Properly maintained: yes
- Periodically checked for Mycoplasma contamination: yes
- Periodically checked for karyotype stability: no
- Periodically "cleansed" against high spontaneous background: yes

Metabolic activation:

with and without

Metabolic activation system:

Rat liver S9-mix induced by a combination of phenobarbital and ß-naphthoflavone

Test concentrations with justification for top dose:

Dose range finding test:
Without and with S9-mix, 3 hours treatment: 17, 52, 164, 512 and 1600 µg/mL
Without S9-mix, 24 hours treatment: 17, 52, 164, 512 and 1600 µg/ml
Experiment 1:
Without and with S9-mix, 3 hours treatment: 0.05, 0.17, 0.5, 1.7, 5.2, 17, 52 and 164 µg/mL
Experiment 2
Without S9-mix, 24 hours treatment: 0.05, 0.17, 0.5, 1.7, 5.2, 17, 52 and 164 µg/mL

Vehicle / solvent:

- Vehicle(s)/solvent(s) used: DMSO
- Justification for choice of solvent/vehicle: At concentrations of 1.7 mg/ml and higher SrHPO4 was suspended in DMSO. At concentrations of 0.52 mg/ml and lower the test substance was dissolved in DMSO. Except in the second experiment where the test substance was still in suspension at 0.52 mg/ml. The stock solution was treated with ultrasonic waves to obtain a homogeneous suspension. DMSO has been accepted and approved by authorities and international guidelines.

Negative solvent / vehicle controls:

yes

Remarks:

(DMSO)

Positive controls:

yes

Positive control substance:

methylmethanesulfonate

Remarks:

without S9. Treatment: 15 µg/mL for the 3 hours treatment period and 5 µg/mL for the 24 hours treatment period

Negative solvent / vehicle controls:

yes

Remarks:

(DMSO)

Positive controls:

yes

Positive control substance:

cyclophosphamide

Remarks:

with S9. 7.5 µg/mL

Details on test system and experimental conditions:

METHOD OF APPLICATION: in medium

DURATION
- Exposure duration:
Short-term treatment
With and without S9-mix: 3 hours
Prolonged treatment period
Without S9-mix: 24 hours
- Expression time (cells in growth medium): 2 days
- Selection time (if incubation with a selection agent): 11 to 12 days

SELECTION AGENT (mutation assays): 5 µg/mL trifluorothymidine (TFT)

NUMBER OF REPLICATIONS:
- Solvent controls: Duplicate cultures
- Treatment groups and positive control: Single cultures

NUMBER OF CELLS EVALUATED: 9.6 x 10E5 cells plated/concentration

DETERMINATION OF CYTOTOXICITY
- Method: relative suspension growth (dose range finding test) and relative total growth (mutation experiments)

Evaluation criteria:

ACCEPTABILITY OF THE ASSAY
A mutation assay was considered acceptable if it met the following criteria:
a) The absolute cloning efficiency of the solvent controls (CEday2) is between 65 and 120% in order to have an acceptable number of surviving cells analysed for expression of the TK mutation.
b) The spontaneous mutation frequency in the solvent control is ≥ 50 per 10^6 survivors and ≤ 170 per 10^6 survivors.
c) The growth rate (GR) over the 2-day expression period for the negative controls should be between 8 and 32 (3 hours treatment) and between 32-180 (24 hours treatment).
d) The mutation frequency of MMS should not be below 500 per 10^6 survivors, and for CP not below 700 per 10^6 survivors.


DATA EVALUATION
Any increase of the mutation frequency should be evaluated for its biological relevance including a comparison of the results with the historical control data range.

A test substance is considered positive (mutagenic) in the mutation assay if it induces a MF of more than MF(controls) + 126 in a dose-dependent manner. An observed increase should be biologically relevant and will be compared with the historical control data range.

A test substance is considered equivocal (questionable) in the mutation assay if no clear conclusion for positive or negative result can be made after an additional confirmation study.

A test substance is considered negative (not mutagenic) in the mutation assay if:
a) None of the tested concentrations reaches a mutation frequency of MF(controls) + 126.
b) The results are confirmed in an independently repeated test.

Statistics:

The global evaluation factor (GEF) has been defined by the IWGT as the mean of the negative/solvent MF distribution plus one standard deviation. For the micro well version of the assay the GEF is 126.

Key result

Species / strain:

mouse lymphoma L5178Y cells

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

no cytotoxicity, but tested up to precipitating concentrations

Vehicle controls validity:

valid

Positive controls validity:

valid

Additional information on results:

TEST-SPECIFIC CONFOUNDING FACTORS:
- Effects of pH: No data
- Effects of osmolality: No data
- Precipitation: Precipitation in the exposure medium was observed at dose levels of 52 µg/mL and above.

RANGE-FINDING/SCREENING STUDIES:
- No toxicity was observed up to the precipitating dose levels of 52 µg/mL and above (up to 1600 µg/mL in the absence and presence of S9-mix.

COMPARISON WITH HISTORICAL CONTROL DATA:
Mutation frequencies of one of the solvent control cultures in the first experiment in the presence of S9-mix and one of the solvent control cultures in the second experiment were recorded to be outside the range of ≥ 50 per 10^6 survivors and ≤ 170 per 10^6 survivors.
Evaluation: The values of 48 and 44 per 10^6 survivors were below the lower limit of the range (50 per 10^6 survivors). The mutation frequencies were just below the lower limit of the range and clear negative results are observed in all experiments, therefore this deviation in the mutation frequency had no effect on the results of the study.

ADDITIONAL INFORMATION ON CYTOTOXICITY:
No toxicity was observed up to and including the highest tested precipitated dose levels in both experiments in the absence and presence of S9-mix.

POSITIVE CONTROLS
Mutation frequencies in cultures treated with positive control chemicals were increased by 17- and 13-fold for MMS in the absence of S9-mix, and 54-fold for CP in the presence of S9-mix, in the first and second experiment respectively. It was therefore concluded that the test conditions, both in the absence and presence of S9-mix, were appropriate for the detection of a mutagenic response and that the metabolic activation system (S9-mix) functioned properly. In addition the observed mutation frequencies of the positive control substances were within the acceptability criteria of this assay

Remarks on result:

other: strain/cell type: Test system L5178Y/TK+/-3.7.2C

Remarks:

Migrated from field 'Test system'.

Conclusions:

Interpretation of results: negative. It is concluded that SrHPO4 is not mutagenic in the mouse lymphoma L5178Y test system under the experimental conditions described in the absence and presence of S9 -mix.

Executive summary:

The mouse lymphoma assay with SrHPO4 was conducted according to OECD 476 guideline and GLP principles.

No toxicity was observed up to and including the highest tested precipitated dose levels in both experiments in the absence and presence of S9-mix. In the absence of S9-mix, SrHPO4 did not induce a significant increase in the mutation frequency in the first experiment. This result was confirmed in an independent repeat experiment with modifications in the duration of treatment time. In the presence of S9-mix, SrHPO4 did not induce a significant increase in the mutation frequency in one experiment. Positive control chemicals, methyl methane sulfonate and cyclophosphamide induced appropriate responses. It is concluded that SrHPO4 is not mutagenic in the TK mutation test system under the experimental conditions described in the absence and presence of S9 -mix.

 

Reference 2

Endpoint:

in vitro cytogenicity / chromosome aberration study in mammalian cells

Remarks:

Type of genotoxicity: chromosome aberration

Type of information:

experimental study

Adequacy of study:

key study

Study period:

February 7, 2014 - March 22, 2014

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Remarks:

The study has been performed according to OECD and/or EC guidelines and according to GLP principles.

Qualifier:

according to guideline

Guideline:

OECD Guideline 473 (In Vitro Mammalian Chromosome Aberration Test)

Version / remarks:

(1997)

Deviations:

no

Qualifier:

according to guideline

Guideline:

EU Method B.10 (Mutagenicity - In Vitro Mammalian Chromosome Aberration Test)

Version / remarks:

(2008)

Deviations:

no

GLP compliance:

yes

Type of assay:

in vitro mammalian chromosome aberration test

Species / strain / cell type:

lymphocytes: Cultured peripheral human lymphocytes

Details on mammalian cell type (if applicable):

- Type and identity of media:
Blood samples
Blood samples were collected by venapuncture using the Venoject multiple sample blood collecting system with a suitable size sterile vessel containing sodium heparin. Immediately after blood collection lymphocyte cultures were started.
- Culture medium
Culture medium consisted of RPMI 1640 medium, supplemented with 20% (v/v) heat-inactivated (56°C; 30 min) foetal calf serum, L-glutamine (2 mM), penicillin/streptomycin (50 U/mL and 50 µg/mL respectively) and 30 U/mL heparin.
- Lymphocyte cultures
Whole blood (0.4 mL) treated with heparin was added to 5 mL or 4.8 mL culture medium (in the absence and presence of S9-mix, respectively). Per culture 0.1 ml (9 mg/mL) phytohaemagglutinin was added.
- Properly maintained: yes
- Periodically checked for Mycoplasma contamination: not applicable, immediately after blood collection lymphocyte cultures were started.
- Periodically checked for karyotype stability: yes
- Periodically "cleansed" against high spontaneous background: not applicable, immediately after blood collection lymphocyte cultures were started.

Metabolic activation:

with and without

Metabolic activation system:

Rat liver S9-mix induced by a combination of phenobarbital and ß-naphthoflavone.

Test concentrations with justification for top dose:

As the test substance precipitated at concentrations of 100 µg/mL and upwards, the following concentrations were tested:

- Dose range finding test/First cytogenetic assay:
Without S9-mix, 3hr exposure; 24 hr fixation: 10, 33 and 100 µg/mL
Without S9-mix, 24/48hr exposure; 24/48 hr fixation: 1, 3, 10, 33, 100, 333 and 1000 µg/mL
(tested beyond the limit of solubility to obtain adequate toxicity data)
With S9-mix (1.8%), 3hr exposure; 24 hr fixation: 10, 33 and 100 µg/mL

Dose levels selected for scoring of chromosome aberrations:
Without S9-mix, 3 h exposure time, 24 h fixation time: 10, 33 and 100 µg/mL
With S9-mix (1.8%), 3 h exposure, 24 h fixation time: 10, 33 and 100 µg/mL

- Second cytogenetic test:
Without S9-mix, 24 hr exposure; 24 hr fixation: 10, 30, 1000, 1250, 1500 and 1836 µg/mL
Without S9-mix, 48 hr exposure; 48 hr fixation: 10, 30, 1000, 1250, 1500 and 1836 µg/mL
With S9-mix (1.8%), 3 hr exposure; 48 hr fixation: 10, 30 and 100 µg/mL

As the precipitate did interfere with the scoring, the dose levels selected for scoring of chromosome aberrations:
Without S9-mix, 24 hr exposure; 24 hr fixation: 30, 1000 and 1250 µg/mL
Without S9-mix, 48 hr exposure; 48 hr fixation: 10, 30 and 1000 µg mL
With S9-mix (1.8%), 3 hr exposure; 48 hr fixation: 10, 30 and 100 µg/mL

Vehicle / solvent:

- Vehicle(s)/solvent(s) used: DMSO
- Justification for choice of solvent/vehicle: a homogeneous suspension could be obtained in DMSO and DMSO is accepted and approved by authorities and international guidelines.

Negative solvent / vehicle controls:

yes

Positive controls:

yes

Positive control substance:

mitomycin C

Remarks:

without S9

Migrated to IUCLID6: in Hank's Balanced Salt Solution: 0.5 µg/mL for a 3 h exposure period, 0.2 µg/mL for a 24 h exposure period and 0.1 µg/mL for a 48 h exposure period

Negative solvent / vehicle controls:

yes

Positive controls:

yes

Positive control substance:

cyclophosphamide

Remarks:

with S9

Migrated to IUCLID6: in Hank's Balanced Salt Solution: 10 µg/mL

Details on test system and experimental conditions:

METHOD OF APPLICATION: in medium

DURATION
- Preincubation period: 48 hr
- Exposure duration: 3 hr (with and without S9-mix), 24 and 48 hr (without S9-mix)
- Fixation time (start of exposure up to fixation or harvest of cells): 24 and 48 hr

SPINDLE INHIBITOR (cytogenetic assays): colchicine
STAIN (for cytogenetic assays): Giemsa

NUMBER OF REPLICATIONS: duplicates in two independent experiments
(except for without S9-mix, 24/48hr exposure; 24/48 hr fixation: 1 replicate)

NUMBER OF CELLS EVALUATED: One hundred metaphase chromosome spreads per culture were examined by light microscopy for chromosome aberrations.

DETERMINATION OF CYTOTOXICITY
- Method: mitotic index of each culture was determined by counting the number of metaphases per 1000 cells

OTHER EXAMINATIONS:
- Determination of polyploidy: yes
- Determination of endoreplication: yes

Evaluation criteria:

A test substance was considered positive (clastogenic) in the chromosome aberration test if:
a) It induced a dose-related statistically significant (Chi-square test, one-sided, p < 0.05) increase in the number of cells with chromosome aberrations.
b) A statistically significant and biologically relevant increase in the frequencies of the number of cells with chromosome aberrations was observed in the absence of a clear dose-response relationship.

A test substance was considered negative (not clastogenic) in the chromosome aberration test if none of the tested concentrations induced a statistically significant (Chi-square test, one-sided, p < 0.05) increase in the number of cells with chromosome aberrations.

The incidence of aberrant cells (cells with one or more chromosome aberrations, gaps included or excluded) for each exposure group outside the laboratory historical control data range was compared to that of the solvent control using Chi-square statistics, considered statistically significant from control group at 95% conf. level.

Statistics:

See above

Key result

Species / strain:

lymphocytes: Cultured peripheral human lymphocytes

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

no cytotoxicity, but tested up to precipitating concentrations

Remarks:

(100 µg/mL)

Vehicle controls validity:

valid

Positive controls validity:

valid

Additional information on results:

- Precipitation in the exposure medium was observed at dose levels of 100 μg/mL and above
- No toxicity was observed up to and including the lowest precipitating tested dose of 100 μg/mL.
- In the dose range finding test, at 1000 μg/mL, the mitotic index was 72% and 66% of control for 24 h exposure time, 24 h fixation time and 48 h exposure time, 48 h fixation time, respectively
- The number of cells with chromosome aberrations found in the solvent and positive control cultures was within the laboratory historical control data range. Positive control chemicals, mitomycin C and cyclophosphamide induced appropriate responses.

Conclusions:

Interpretation of results: negative

A chromosome aberration study with the substance was performed according to OECD 473 guideline and GLP principles, in cultured peripheral human lymphocytes in two independent experiments. It is concluded that the substance is not clastogenic in human lymphocytes.

Executive summary:

In accordance with OECD 473 (1998) and according to GLP principles, a chromosome aberration study with the substance was performed in cultured peripheral human lymphocytes in two independent experiments with and without metabolic activation. Adequate solvent and positive controls were included. The substance was tested up to and above precipitating concentrations (100 µg/mL).

The substance did not induce a statistically significant or biologically relevant increase in the number of cells with chromosome aberrations in the absence and presence of S9-mix, in either of the two independently repeated experiments. No effects of the substance on the number of polyploid cells and cells with endoreduplicated chromosomes were observed both in the absence and presence of S9-mix. Based on the results of this study, it is concluded that the substance does not disturb mitotic processes and cell cycle progression and does not induce numerical chromosome aberrations.

Reference 3

Endpoint:

in vitro gene mutation study in bacteria

Remarks:

Type of genotoxicity: gene mutation

Type of information:

experimental study

Adequacy of study:

key study

Study period:

February 27, 2014 - March 13, 2014

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Remarks:

The study has been performed according to OECD and/or EC guidelines and according to GLP principles.

Qualifier:

according to guideline

Guideline:

OECD Guideline 471 (Bacterial Reverse Mutation Assay)

Version / remarks:

(1997)

Deviations:

no

Qualifier:

according to guideline

Guideline:

EU Method B.13/14 (Mutagenicity - Reverse Mutation Test Using Bacteria)

Version / remarks:

(2008)

Deviations:

no

GLP compliance:

yes

Type of assay:

bacterial reverse mutation assay

Target gene:

- S. typhimurium: Histidine gene
- E. coli: Tryptophan gene

Species / strain / cell type:

S. typhimurium TA 1535, TA 1537, TA 98 and TA 100

Species / strain / cell type:

E. coli WP2 uvr A

Metabolic activation:

with and without

Metabolic activation system:

Rat liver S9-mix induced by Aroclor

Test concentrations with justification for top dose:

Experiment 1
Preliminary test (without and with 5% (v/v) S9-mix), TA100 and WP2uvrA: 3, 10, 33, 100, 333, 1000, 3330 and 5000 µg/plate
Main study: TA1535, TA1537 and TA98:
Without and with 5% (v/v) S9-mix: 33, 100, 333, 1000 and 3330 μg/plate
Experiment 2:
Without and with 10% (v/v) S9-mix: 33, 100, 333, 1000, 3330 and 5000 μg/plate

Vehicle / solvent:

- Vehicle(s)/solvent(s) used: DMSO
- Justification for choice of solvent/vehicle: a homogeneous suspension could be obtained in DMSO and DMSO is accepted and approved by authorities and international guidelines.

Untreated negative controls:

no

Negative solvent / vehicle controls:

yes

Remarks:

(DMSO)

Positive controls:

yes

Positive control substance:

other: See the section "Any other information on materials and methods incl. tables"

Details on test system and experimental conditions:

METHOD OF APPLICATION: in agar (plate incorporation)

DURATION
- Exposure duration (preliminary test): 69 hours
- Exposure duration (main study): 48 ± 4 hours

NUMBER OF REPLICATIONS:
- Doses of the test substance were tested in triplicate in each strain. Two independent experiments were conducted.

NUMBER OF CELLS EVALUATED: 10E8 per plate

DETERMINATION OF CYTOTOXICITY
- Method: The reduction of the bacterial background lawn, the increase in the size of the microcolonies and the reduction of the revertant colonies.

OTHER EXAMINATIONS:
- The presence of precipitation of the test compound on the plates was determined.

Evaluation criteria:

A test substance is considered negative (not mutagenic) in the test if:
a) The total number of revertants in tester strain TA100 is not greater than two (2) times the concurrent control, and the total number of revertants in tester strains TA1535, TA1537, TA98 or WP2uvrA is not greater than three (3) times the concurrent control.
b) The negative response should be reproducible in at least one independently repeated experiment.

A test substance is considered positive if:
a) A two-fold (TA100) or more or a three-fold (TA1535, TA1537, TA98, WP2uvrA) or more increase above solvent control in the mean number of revertant colonies is observed in the test substance group.
b) In case a repeat experiment is performed when a positive response is observed in one of the tester strains, the positive response should be reproducible in at least one independently repeated experiment.

Key result

Species / strain:

S. typhimurium TA 98

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

no cytotoxicity, but tested up to precipitating concentrations

Vehicle controls validity:

valid

Positive controls validity:

valid

Key result

Species / strain:

S. typhimurium TA 100

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

no cytotoxicity, but tested up to precipitating concentrations

Vehicle controls validity:

valid

Positive controls validity:

valid

Key result

Species / strain:

S. typhimurium TA 1535

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

no cytotoxicity, but tested up to precipitating concentrations

Vehicle controls validity:

valid

Positive controls validity:

valid

Key result

Species / strain:

S. typhimurium TA 1537

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

no cytotoxicity, but tested up to precipitating concentrations

Vehicle controls validity:

valid

Positive controls validity:

valid

Key result

Species / strain:

E. coli WP2 uvr A

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

no cytotoxicity nor precipitates, but tested up to recommended limit concentrations

Vehicle controls validity:

valid

Positive controls validity:

valid

Additional information on results:

TEST-SPECIFIC CONFOUNDING FACTORS
- Precipitation: Slight precipitation was observed in all strains from 3330 µg/plate onwards.

RANGE-FINDING/SCREENING STUDIES:
- No toxicity or mutagenicity was observed up to and including the top dose of 5000 µg/plate

COMPARISON WITH HISTORICAL CONTROL DATA:
- The negative and strain-specific positive control values were within our laboratory historical control data ranges indicating that the test conditions were adequate and that the metabolic activation system functioned properly.

ADDITIONAL INFORMATION ON CYTOTOXICITY:
- No toxicity or mutagenicity was observed up to and including the top dose of 5000 µg/plate

Conclusions:

Interpretation of results: negative

The mutagenic activity of the substance was evaluated in accordance with OECD 471 (1997) and according to GLP principles. Based on the results of this study it is concluded that the substance is not mutagenic in the Salmonella typhimurium reverse mutation assay and in the Escherichia coli reverse mutation assay with and without metabolic activation.

Executive summary:

The mutagenic activity of the substance was evaluated in accordance with OECD 471 (1997) and according to GLP principles. The test was performed in two independent experiments, both in the absence and presence of S9-mix. The substance was tested up to or beyond a precipitating dose level. No cytotoxicity was observed up to the limit concentration.

Adequate solvent and positive controls were included. The substance did not induce a significant dose-related increase in the number of revertant (His+) colonies in each of the four S. typhimurium tester strains (TA1535, TA1537, TA98 and TA100) and in the number of revertant (Trp+) colonies in tester strain WP2uvrA, both in the absence and presence of S9-metabolic activation. These results were confirmed in independently repeated experiments. Based on the results of this study it is concluded that the substance is not mutagenic in the Salmonella typhimurium reverse mutation assay and in the Escherichia coli reverse mutation assay with and without metabolic activation.

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (negative)

Genetic toxicity in vivo

Endpoint conclusion

Endpoint conclusion:

no study available

Additional information

The mutagenic activity of the substance was evaluated in accordance with OECD 471 (1997) and according to GLP principles. The test was performed in two independent experiments, both in the absence and presence of S9-mix. The substance was tested up to or beyond a precipitating dose level. No cytotoxicity was observed up to the limit concentration. Adequate solvent and positive controls were included. The substance did not induce a significant dose-related increase in the number of revertant (His+) colonies in each of the four S. typhimurium tester strains (TA1535, TA1537, TA98 and TA100) and in the number of revertant (Trp+) colonies in tester strain WP2uvrA, both in the absence and presence of S9-metabolic activation. These results were confirmed in independently repeated experiments. Based on the results of this study it is concluded that the substance is not mutagenic in the Salmonella typhimurium reverse mutation assay and in the Escherichia coli reverse mutation assay with and without metabolic activation.

 

In accordance with OECD 473 (1998) and according to GLP principles, a chromosome aberration study with the substance was performed in cultured peripheral human lymphocytes in two independent experiments with and without metabolic activation. Adequate solvent and positive controls were included. The substance was tested up to and above precipitating concentrations (100 µg/mL). The substance did not induce a statistically significant or biologically relevant increase in the number of cells with chromosome aberrations in the absence and presence of S9-mix, in either of the two independently repeated experiments. No effects of the substance on the number of polyploid cells and cells with endoreduplicated chromosomes were observed both in the absence and presence of S9-mix. Based on the results of this study, it is concluded that the substance does not disturb mitotic processes and cell cycle progression and does not induce numerical chromosome aberrations.

 

A mouse lymphoma assay with SrHPO4 was conducted according to OECD 476 guideline and GLP principles.

No toxicity was observed up to and including the highest tested precipitated dose levels in both experiments in the absence and presence of S9-mix. In the absence of S9-mix, SrHPO4 did not induce a significant increase in the mutation frequency in the first experiment. This result was confirmed in an independent repeat experiment with modifications in the duration of treatment time. In the presence of S9-mix, SrHPO4 did not induce a significant increase in the mutation frequency in one experiment. Positive control chemicals, methyl methane sulfonate and cyclophosphamide induced appropriate responses.It is concluded that SrHPO4 is not mutagenic in the TK mutation test system under the experimental conditions described in the absence and presence of S9 -mix.

Justification for selection of genetic toxicity endpoint
No single study was selected as key study, as the endpoint conclusion is derived by weight-of-evidence using three in vitro studies.

Short description of key information:
Three in vitro studies are available with Strontium hydrogenphosphate. All studies were performed according to OECD/EC guidelines and GLP principles (Klimisch 1). In all studies, the test substance was negative with and without metabolic activation.

Endpoint Conclusion: No adverse effect observed (negative)

 

Justification for classification or non-classification

Based on the available data, Strontium hydrogenphosphate is not classified for genotoxicity according to the criteria specified by the CLP Regulation.