Strontium di(acetate)

Endpoint summary

Key value for chemical safety assessment

Genetic toxicity in vitro

Description of key information

Strontium substances have been tested in bacterial reverse mutation assays, in vitro gene mutation and chromosome aberration test. The tests show a negative response, thus strontium acetate is not to be classified as mutagenic.

Link to relevant study records

Reference

Reference 1

Endpoint:

in vitro gene mutation study in bacteria

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

key study

Study period:

The study was performed between 10 December 1996 and 03 February 1997.

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study without detailed documentation

Justification for type of information:

As few data are available on the target substance, a research of the potential analogues has been carried out.
The hypothesis is that properties are likely to be similar or follow a similar pattern as a result of the presence of a common metal ion (or ion complex including a hydrated metal ion). This is a reasonable assumption for the majority of inorganic compounds and some organic compounds (e.g. metal salts of some organic acids).
The following points are be considered:
- Chemical speciation and valency,
- The water solubility, as it provides a first indication of the availability of the metal ion in the different compartments of interest. The most simplistic approach to hazard evaluation is to assume that the specific metal-containing compound to be evaluated shows the same hazards as the most water-soluble compounds.
- Counter ions: the assumption that the metal ion is responsible for the common property or effect implies that the toxicity of the counter ion present in the compound will be largely irrelevant in producing the effects to be assessed.
Based on these data, we have selected the analogue Strontium chloride.
Strontium has also physiochemical properties similar to calcium and both appear mainly in ionic form in water.

A detail description is provided as attached report of this endpoint in this Iuclid file.

Reason / purpose for cross-reference:

read-across source

Key result

Species / strain:

S. typhimurium TA 1535

Metabolic activation:

with and without

Genotoxicity:

negative

Remarks:

No significant increase in the frequency of revertant colonies of bacteria were recorded for any of the strains of S. typhimurium used, at any dose level.

Cytotoxicity / choice of top concentrations:

no cytotoxicity

Remarks:

No toxicity was exhibited to any of the strains tested.

Vehicle controls validity:

valid

Untreated negative controls validity:

not examined

Positive controls validity:

valid

Key result

Species / strain:

S. typhimurium TA 1537

Metabolic activation:

with and without

Genotoxicity:

negative

Remarks:

No significant increase in the frequency of revertant colonies of bacteria were recorded for any of the strains of S. typhimurium used, at any dose level.

Cytotoxicity / choice of top concentrations:

no cytotoxicity

Remarks:

No toxicity was exhibited to any of the strains tested.

Vehicle controls validity:

valid

Untreated negative controls validity:

not examined

Positive controls validity:

valid

Key result

Species / strain:

S. typhimurium TA 98

Metabolic activation:

with and without

Genotoxicity:

negative

Remarks:

No significant increase in the frequency of revertant colonies of bacteria were recorded for any of the strains of S. typhimurium used, at any dose level.

Cytotoxicity / choice of top concentrations:

no cytotoxicity

Remarks:

No toxicity was exhibited to any of the strains tested.

Vehicle controls validity:

valid

Untreated negative controls validity:

not examined

Positive controls validity:

valid

Key result

Species / strain:

S. typhimurium TA 100

Metabolic activation:

with and without

Genotoxicity:

negative

Remarks:

No significant increase in the frequency of revertant colonies of bacteria were recorded for any of the strains of S. typhimurium used, at any dose level.

Cytotoxicity / choice of top concentrations:

no cytotoxicity

Remarks:

No toxicity was exhibited to any of the strains tested.

Vehicle controls validity:

valid

Untreated negative controls validity:

not examined

Positive controls validity:

valid

Key result

Species / strain:

S. typhimurium TA 1538

Metabolic activation:

with and without

Genotoxicity:

negative

Remarks:

No significant increase in the frequency of revertant colonies of bacteria were recorded for any of the strains of S. typhimurium used, at any dose level.

Cytotoxicity / choice of top concentrations:

no cytotoxicity

Remarks:

No toxicity was exhibited to any of the strains tested.

Vehicle controls validity:

valid

Untreated negative controls validity:

not examined

Positive controls validity:

valid

Additional information on results:

TEST-SPECIFIC CONFOUNDING FACTORS
No details are reported.

RANGE-FINDING/SCREENING STUDIES:
The dose range of the test material used in the preliminary toxicity study was 0, 50, 150, 500, 1500 and 5000 µg/plate. The test material was non-toxic to the strain of S. typhimurium TA100.

COMPARISON WITH HISTORICAL CONTROL DATA:
no data

ADDITIONAL INFORMATION ON CYTOTOXICITY:
No further details are reported.

Conclusions:

Interpretation of results (migrated information):
negative

In conclusion, under the test conditions described the test material, strontium chloride-6-hydrate extra pure, was considered to be non-mutagenic either with or without metabolic activation at any concentration tested.

Executive summary:

S. typhimurium strains TA1535, TA1537, TA1538, TA98 and TA100 were treated with the test material using the Ames plate incorporation method at 5 dose levels, both with and without metabolic activation. The dose range was determined in a preliminary toxicity assay and was 50 to 5000 µg/plate in the first experiment. The experiment was repeated on a separate day using the same dose range as experiment 1.

Positive and vehicle controls were included in the test.

The test material caused no visible reduction in the growth of the bacterial lawn at any of the dose levels to any of the strains of Salmonella tested.

No significant increase in the frequency of revertant colonies was recorded for any of the bacterial strains with any of the concentrations tested, either with or without metabolic activation.

Reference 2

Endpoint:

in vitro cytogenicity / micronucleus study

Remarks:

Type of genotoxicity: chromosome aberration

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

key study

Study period:

Study started on 15 December 2009 and was completed on 11 February 2010.

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: GLP guideline study

Justification for type of information:

As few data are available on the target substance, a research of the potential analogues has been carried out.
The hypothesis is that properties are likely to be similar or follow a similar pattern as a result of the presence of a common metal ion (or ion complex including a hydrated metal ion). This is a reasonable assumption for the majority of inorganic compounds and some organic compounds (e.g. metal salts of some organic acids).
The following points are be considered:
- Chemical speciation and valency,
- The water solubility, as it provides a first indication of the availability of the metal ion in the different compartments of interest. The most simplistic approach to hazard evaluation is to assume that the specific metal-containing compound to be evaluated shows the same hazards as the most water-soluble compounds.
- Counter ions: the assumption that the metal ion is responsible for the common property or effect implies that the toxicity of the counter ion present in the compound will be largely irrelevant in producing the effects to be assessed.
Based on these data, we have selected the analogue Strontium nitrate.
Strontium has also physiochemical properties similar to calcium and both appear mainly in ionic form in water.

A detail description is provided as attached report of this endpoint in this Iuclid file.

Reason / purpose for cross-reference:

read-across source

Species / strain:

lymphocytes: from humans

Metabolic activation:

with and without

Genotoxicity:

negative

Remarks:

Treatment of cells with Strontium nitrate (+/- S9) resulted in frequencies of MNBN cells that were similar to (and not significantly different from) those observed in concurrent vehicle controls at all concentrations analysed. For details see table below.

Cytotoxicity / choice of top concentrations:

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

Vehicle controls validity:

valid

Untreated negative controls validity:

not examined

Positive controls validity:

valid

Additional information on results:

TEST-SPECIFIC CONFOUNDING FACTORS
- Effects of pH and osmolality: No marked changes in osmolality or pH were observed at the highest concentration tested in the cytotoxicity Range-Finder (2116 µg/mL), compared to the concurrent vehicle controls (individual data not reported).
- Water solubility: Preliminary solubility data indicated that Strontium nitrate was soluble in purified water at concentrations up to at least 58.53 mg/mL. The solubility limit in culture medium was in excess of 5853 µg/mL.

RANGE-FINDING/SCREENING STUDIES: The results of the cytotoxicity Range-Finder Experiment were used to select suitable maximum concentrations for the Main Experiment.

COMPARISON WITH HISTORICAL CONTROL DATA: yes; The MNBN cell frequency of all Strontium nitrate treated cultures fell within normal ranges.

ADDITIONAL INFORMATION ON CYTOTOXICITY: no further data

Remarks on result:

other: all strains/cell types tested

Remarks:

Migrated from field 'Test system'.

Main experiment (48 hours PHA) - Summary of results

Treatment	Concentration (mg/mL)	Cytotoxicity (%)	Mean MNBN cell frequency (%)	Historical(%) #	Statistical significance
3+21 hour -S-9	Vehicle^a	-	0.62	0.1-1.2	-
Trial 2	1200	0	0.32		NS
	1500	0	0.34		NS
	1800	0	0.79		NS
	*MMC, 0.80	ND	11.02		p<0.001
	*VIN, 0.02♦	ND	4.86		p<0.001
3+21 hour +S-9	Vehicle^a	-	0.32	0.0-1.2	-
Trial 2	800.0	0	0.39		NS
	1200	0	0.42		NS
	1500	0	0.34		NS
	*CPA, 12.5	ND	2.03		p<0.001
24+0 hour -S-9	Vehicle^a	-	0.25	0.1-1.2	-
Trial 1	1500	5	0.20		NS
	1800	19	0.20		NS
	2116	10	0.25		NS
	*VIN, 0.02	ND	4.40		p<0.001
	*MMC, 0.80♥	ND	8.45		p<0.001
♦ 24+0 hour –S-9 treatment ♥ 3+21 hour –S-9 treatment ^aVehicle control waspurified water * Positive control ^#95^thpercentile of the observed range NS = Not significant          ND = Not determined

Conclusions:

Interpretation of results (migrated information):
negative

It is concluded that Strontium nitrate did not induce micronuclei in cultured human peripheral blood lymphocytes when tested in excess of the limit of solubility in both the absence and presence of S-9.

Executive summary:

Strontium nitrate was tested in an in vitro micronucleus assay using human lymphocytes, both in the absence and presence of metabolic activation.

Treatments covering a broad range of concentrations, the highest concentration used in the Main Experiment, 2116 mg/mL, (equivalent to 10 mM) was determined following a preliminary cytotoxicity Range-Finder Experiment.

Treatments were conducted 48 hours following mitogen stimulation by Phytohaemagglutinin (PHA). In the Main Experiment, micronuclei were analysed at 3 concentrations. Appropriate vehicle control cultures were included in the test system under each treatment condition.

Treatment of cells with Strontium nitrate in the absence and presence of S9 mix resulted in frequencies of MNBN cells that were similar to (and not significantly different from) those observed in concurrent vehicle controls at all concentrations analysed under all treatment conditions. The MNBN cell frequency of all Strontium nitrate treated cultures fell within normal ranges.

Reference 3

Endpoint:

in vitro gene mutation study in mammalian cells

Remarks:

Type of genotoxicity: gene mutation

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

key study

Study period:

Study started on 16 December 2009 and was completed on 1 March 2010.

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: GLP guideline study

Justification for type of information:

As few data are available on the target substance, a research of the potential analogues has been carried out.
The hypothesis is that properties are likely to be similar or follow a similar pattern as a result of the presence of a common metal ion (or ion complex including a hydrated metal ion). This is a reasonable assumption for the majority of inorganic compounds and some organic compounds (e.g. metal salts of some organic acids).
The following points are be considered:
- Chemical speciation and valency,
- The water solubility, as it provides a first indication of the availability of the metal ion in the different compartments of interest. The most simplistic approach to hazard evaluation is to assume that the specific metal-containing compound to be evaluated shows the same hazards as the most water-soluble compounds.
- Counter ions: the assumption that the metal ion is responsible for the common property or effect implies that the toxicity of the counter ion present in the compound will be largely irrelevant in producing the effects to be assessed.
Based on these data, we have selected the analogue Strontium nitrate.
Strontium has also physiochemical properties similar to calcium and both appear mainly in ionic form in water.

A detail description is provided as attached report of this endpoint in this Iuclid file.

Reason / purpose for cross-reference:

read-across source

Species / strain:

mouse lymphoma L5178Y cells

Metabolic activation:

with and without

Genotoxicity:

negative

Remarks:

No statistically significant increases in mutant frequency were observed following treatment with Strontium nitrate at any concentration tested in Experiments I and II and there were no statistically significant linear trends.

Cytotoxicity / choice of top concentrations:

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

Vehicle controls validity:

valid

Untreated negative controls validity:

not examined

Positive controls validity:

valid

Additional information on results:

TEST-SPECIFIC CONFOUNDING FACTORS
- Effects of pH and osmolality: No marked changes in osmolality or pH were observed at the highest concentration tested in the cytotoxicity Range-Finder (2116 µg/mL), compared to the concurrent vehicle controls (individual data not reported).
- Water solubility: Preliminary solubility data indicated that Strontium nitrate was soluble in sterile water for irrigation (purified water) at concentrations up to at least 58.53 mg/mL. The solubility limit in culture medium was less than 5853 µg/mL, as indicated by precipitation which was observed at this concentration at least 3 hours after test article addition (no lower concentrations were assessed).
- Precipitation: Precipitation was observed in the Range-Finder test following treatment incubation period at a concentration of 2116 µg/mL. In Experiment I and II, after the 3 hour treatment incubation period, precipitate was observed at the highest 3 concentrations in the absence of S9 mix (1800 to 2116 µg/mL) and at the highest 4 concentrations in the presence of S9 mix (1600 to 2116 µg/mL).

RANGE-FINDING/SCREENING STUDIES: In the cytotoxicity Range-Finder Experiment, 6 concentrations were tested in the absence and presence of S9 mix, ranging from 66.13 to 2116 µg/mL (equivalent to 10 mM at the highest concentration tested). The highest concentration to provide >10% RS was 1058 µg/mL, which gave 63% and 71% RS in the absence and presence of S 9, respectively.

COMPARISON WITH HISTORICAL CONTROL DATA: yes; results for positive controls were compared with historical means.

ADDITIONAL INFORMATION ON CYTOTOXICITY: no further data

Remarks on result:

other: all strains/cell types tested

Remarks:

Migrated from field 'Test system'.

Conclusions:

Interpretation of results (migrated information):
negative

It is concluded that Strontium nitrate did not induce mutation at the hprt locus of L5178Y mouse lymphoma cells when tested under the conditions employed in this study. These conditions included treatments up to precipitating concentrations in two independent experiments in the absence and presence of a rat liver metabolic activation system (S9 mix).

Executive summary:

Strontium nitrate was assayed for mutation at the hypoxanthine-guanine phosphoribosyl transferase (hprt) locus (6 -thioguanine [6TG] resistance) in mouse lymphoma cells using a fluctuation protocol. The study consisted of a cytotoxicity Range-Finder Experiment followed by two independent experiments, each conducted in the absence and presence of metabolic activation (S9 mix).

According to the results from a Range-Finder test, for Experiment I 10 concentrations, ranging from 250 to 2116 µg/mL were tested in the absence and presence of S9 mix. 7 days after treatment, the highest concentrations selected to determine viability and 6TG resistance were 1800 µg/mL in the absence of S9 mix and 1600 µg/mL in the presence of S9 mix (both limited by the appearance of post-treatment precipitate), which gave 56% and 70%  relative survival (RS), respectively.

In Experiment II 10 concentrations, ranging from 200 to 2116 µg/mL were tested in the absence and presence of S9 mix. 7 days after treatment, the highest concentrations selected to determine viability and 6TG resistance were 1800 µg/mL in the absence of S9 mix and 1600 µg/mL in the presence of S9 mix (both limited by the appearance of post-treatment precipitate), which gave 32% and 36% RS, respectively.

Negative (vehicle) and positive control treatments were included in each Mutation Experiment.

No statistically significant increases in mutant frequency were observed following treatment with Strontium nitrateat any concentration tested in the absence or presence of S9 in Experiments I and II and there were no statistically significant linear trends.

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (negative)

Genetic toxicity in vivo

Description of key information

Positive results were reported on strontium chloride and strontium ranelate. However these data are considered as not reliable due to method deficiencies.

As all the other validated results are negative, strontium acetate is considered to have no mutagenicity / genotoxicity effects.

Link to relevant study records

Reference

Reference 1

Endpoint:

in vivo mammalian somatic cell study: cytogenicity / bone marrow chromosome aberration

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

weight of evidence

Reliability:

3 (not reliable)

Rationale for reliability incl. deficiencies:

significant methodological deficiencies

Justification for type of information:

As few data are available on the target substance, a research of the potential analogues has been carried out.
The hypothesis is that properties are likely to be similar or follow a similar pattern as a result of the presence of a common metal ion (or ion complex including a hydrated metal ion). This is a reasonable assumption for the majority of inorganic compounds and some organic compounds (e.g. metal salts of some organic acids).
The following points are be considered:
- Chemical speciation and valency,
- The water solubility, as it provides a first indication of the availability of the metal ion in the different compartments of interest. The most simplistic approach to hazard evaluation is to assume that the specific metal-containing compound to be evaluated shows the same hazards as the most water-soluble compounds.
- Counter ions: the assumption that the metal ion is responsible for the common property or effect implies that the toxicity of the counter ion present in the compound will be largely irrelevant in producing the effects to be assessed.
Based on these data, we have selected the analogue Strontium chloride.
Strontium has also physiochemical properties similar to calcium and both appear mainly in ionic form in water.

A detail description is provided as attached report of this endpoint in this Iuclid file.

Reason / purpose for cross-reference:

read-across source

Key result

Sex:

male/female

Genotoxicity:

positive

Toxicity:

not specified

Vehicle controls validity:

valid

Negative controls validity:

not applicable

Positive controls validity:

not applicable

Additional information on results:

Trend test value for chromosomal aberrations of mice fed strontium chloride (Z value):
6h : 6.184 (male), 6.67 (female)
12h: 5.209 (male), 6.725 (female)
24h: 6.797 (male), 7.689 (female)
All results have a p-value < 0.001 (significant results)

Conclusions:

Strontium chloride has shown mutagenicity on bone marrow cells of mice.
Positive results was reported on strontium chloride in this study. However this result is considered as not reliable due to method deficiencies and is indicated in a weight of evidence approach.

Reference 2

Endpoint:

genetic toxicity in vivo, other

Remarks:

in vivo mammalian somatic cell study: cytogenicity / bone marrow and peripheral blood micronucleus assay

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

weight of evidence

Reliability:

3 (not reliable)

Rationale for reliability incl. deficiencies:

significant methodological deficiencies

Remarks:

Reliability 3 because of no historical control, only one dose level and low number of scored cells.

Justification for type of information:

As few data are available on the target substance, a research of the potential analogues has been carried out.
The hypothesis is that properties are likely to be similar or follow a similar pattern as a result of the presence of a common metal ion (or ion complex including a hydrated metal ion). This is a reasonable assumption for the majority of inorganic compounds and some organic compounds (e.g. metal salts of some organic acids).
The following points are be considered:
- Chemical speciation and valency,
- The water solubility, as it provides a first indication of the availability of the metal ion in the different compartments of interest. The most simplistic approach to hazard evaluation is to assume that the specific metal-containing compound to be evaluated shows the same hazards as the most water-soluble compounds.
- Counter ions: the assumption that the metal ion is responsible for the common property or effect implies that the toxicity of the counter ion present in the compound will be largely irrelevant in producing the effects to be assessed.
Based on these data, we have selected the analogue Strontium nitrate.
Strontium has also physiochemical properties similar to calcium and both appear mainly in ionic form in water.

A detail description is provided as attached report of this endpoint in this Iuclid file.

Reason / purpose for cross-reference:

read-across source

Key result

Sex:

female

Genotoxicity:

positive

Toxicity:

yes

Vehicle controls validity:

valid

Negative controls validity:

valid

Positive controls validity:

valid

Additional information on results:

Significant difference between SR-treated rats and negative control rats for micronucleus induction.
In peripheral blood and bone marrow tissue, although the MNPCE frequencies (4.80±0.48 and 5.00±0.31, respectively) in rats treated with SR were significantly higher than the frequency in negative control (1.60±0.24 and 2.20±0.20, respectively), they were much less than the MNPCE frequency induced by the positive control, 2 mg/kg MMC (41.0 ±0.44, 42.4±0.92, respectively).
SR treatment significantly decreased the PCE number when compared to controls in both bone marrow and peripheral blood (p < 0.001).
SR is a toxic substance in both bone marrow at acute treatment and peripheral blood at chronic treatment:
- PCE number: 2.60±0.25 in the control group, 1.2±0.20 in the SR group at chronic treatment
- PCE number: 103±1.40 in the control group, 76.8±1.82in the SR group at acute treatment

Conclusions:

Chronical and acute administration of strontium ranelate (500 mg/kg) significantly increased the frequency of MNPCEs (micronucleus in polychromatic (immature) erythrocytes) and decreased the % PCEs (polychromatic erythrocytes) in wistar rat peripheral blood.
Positive results was reported on strontium ranelate in this study. However this result is considered as not reliable due to method deficiencies.

Executive summary:

In this study, rats were treated by gavage with 500 mg/kg of strontium ranelate dissolved in saline three times per week for 12 weeks (chronic treatment) and 24 hours (acute treatment). The genotoxic potential of strontium ranelate was investigated in Wistar rat peripheral blood, using the micronucleus (MN) test systems. Strontium ranelate induced micronucleus formation in peripheral blood and bone marrow of rats.

Endpoint conclusion

Endpoint conclusion:

no study available

Additional information

Ames test: Read across from SrCl2 to strontium acetate is envisaged due to the fact that possible effects occurred could be regarded as strontium ion related effects. Both substances (SrCl2 and strontium acetate) are "very soluble" (above 10 g/L at 20°C) in water. Hence, it could be concluded that read across is possible. Nevertheless, tests on the mutagenic potential of strontium compounds in bacteria are considered dispensable for principal considerations, since inorganic metal compounds are frequently negative in this assay due to limited capacity for uptake of metal ions (Guidance on information requirements and chemical safety assessment, Chapter R.7a, p. 565; HERAG facts sheet mutagenicity, Chapter 2.1).

It is concluded that strontium acetate did not induce micronuclei in cultured human peripheral blood lymphocytes following treatments in the absence and presence of an Aroclor induced rat liver metabolic activation system (S-9 mix). Concentrations were tested and analysed up to 2116 µg/mL.

It is concluded that strontium acetate did not induce mutation at the tk locus of L5178Y mouse lymphoma cells when tested under the conditions employed in this study .

These conditions included treatments up to precipitating concentrations in two independent experiments, in the absence and presence of a rat liver metabolic activation system (S-9 mix).

Further testing of in vivo genetic toxicity tests is not considered necessary.

Justification for classification or non-classification

Strontium acetate could be regarded to have no mutagenicity / genotoxicity effects, tested in vitro. Hence, no classification and labelling is required.