Praseodymium(III,IV) oxide

Genetic toxicity: in vitro

Administrative data

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:

22 May 2007 - 17 December 2007

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: Study conducted to GLP in compliance with agreed protocols, with no or minor deviations from standard test guidelines and/or minor methodological deficiencies, which do not affect the quality of the relevant results.

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2007

Report date:

2007

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

OECD Guideline 471 (Bacterial Reverse Mutation Assay)

Deviations:

no

Test guideline 2

Qualifier:

according to guideline

Guideline:

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

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Type of assay:

bacterial reverse mutation assay

Test material

Test material information

Constituent 1

Reference substance name:

Praseodymium(III,IV) oxide

EC Number:

234-857-9

EC Name:

Praseodymium(III,IV) oxide

Cas Number:

12037-29-5

Molecular formula:

O11Pr6

IUPAC Name:

tetrakis(λ⁴-praseodymium(4+)) dipraseodymium(3+) undecaoxidandiide

Test material form:

solid: particulate/powder

Details on test material:

- Substance type: mono-constituent substance
- Physical state: solid (black powder)
- Storage condition of test material: at room temperature, protected from light and humidity

Method

Target gene:

S. typhimurium: Histidine locus.

Species / strain

Species / strain / cell type:

S. typhimurium TA 1535, TA 1537, TA 98, TA 100 and TA 102

Additional strain / cell type characteristics:

other: rfa mutation; uvrB mutation (except TA102); addition of plasmid pKM101 to TA98, TA100 and TA102.

Metabolic activation:

with and without

Metabolic activation system:

S9 mix prepared from a liver post-mitochondrial fraction of rats induced with Aroclor 1254

Test concentrations with justification for top dose:

312.5, 625, 1250, 2500 and 5000 µg/plate for the three experiments, with and without S9 mix.

Vehicle / solvent:

- Vehicle(s)/solvent(s) used: DMSO
- Justification for choice of solvent/vehicle: test material is insoluble in most vehicles - formed homogeneous suspension to the naked eye in DMSO. Suspended at the concentration of 100 mg/mL.
- volume of vehicle/solvent in the medium: 0.05 mL per 2.60 mL medium

Controls

Untreated negative controls:

no

Negative solvent / vehicle controls:

yes

True negative controls:

no

Positive controls:

yes

Positive control substance:

9-aminoacridine

2-nitrofluorene

sodium azide

benzo(a)pyrene

mitomycin C

other: 2-Anthramine

Details on test system and experimental conditions:

METHOD OF APPLICATION: All experiments were performed according to the direct plate incorporation method except for the second and third test with S9 mix, which were performed according to the preincubation method.

DURATION
- Preincubation period: 60 minutes, 37 °C
- Exposure duration: 48 to 72 hours

NUMBER OF REPLICATES: three plates/dose-level

OTHER: SCORING METHOD: automated

Evaluation criteria:

A reproducible 2-fold increase (for the TA 98, TA 100 and TA 102 strains) or 3-fold increase (for the TA 1535 and TA 1537 strains) in the number of revertants compared with the vehicle controls, in any strain at any dose-level and/or evidence of a dose-response was considered as a positive result. Reference to historical data, or other considerations of biological relevance were taken into account in the evaluation of the data obtained.

Results and discussion

Test results

Key result

Species / strain:

S. typhimurium TA 1535, TA 1537, TA 98, TA 100 and TA 102

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

Untreated negative controls validity:

not applicable

Positive controls validity:

valid

Additional information on results:

TEST-SPECIFIC CONFOUNDING FACTORS
- Precipitation: A moderate to strong precipitate was observed in the Petri plates when scoring the revertants at dose-levels ≥ 312.5 µg/plate (the precipitate did not interfere with the scoring).

RANGE-FINDING/SCREENING STUDIES:
To assess the toxicity of the test material to the bacteria, six dose-levels (one plate/dose-level) were tested in the TA 98, TA 100 and TA 102 strains, with and without S9 mix. The evaluation of the toxicity was performed on the basis of the observation of the decrease in the number of revertant colonies and/or a thinning of the bacterial lawn.
A moderate to strong precipitate was observed in the Petri plates when scoring the revertants at dose-levels ≥ 100 µg/plate. No noteworthy toxicity was noted towards the three strains used, either with or without S9 mix.

COMPARISON WITH HISTORICAL CONTROL DATA: The control data reported in these report are in the range of the historical control data observed in the laboratory. The study was therefore considered valid.

Results
In the first experiment, no noteworthy toxicity was induced in any of the five tester strains with and without S9 mix. In the second experiment with S9 mix (preincubation method) with the TA 98 strain, up to 3.3-fold increase in the number of revertants were noted, without any clear evidence of dose-relationship. A third experiment was performed with this strain under the same experimental conditions in order to check the reliability of these slight increases. No confirmation of the increase in the number of revertants was observed in this third experiment. The test material did not induce any noteworthy increase in the number of revertants, either with or without S9 mix, in any of the remaining tester strains.

Remarks on result:

other: all strains/cell types tested

Any other information on results incl. tables

Table 2: First experiment (direct plate incorporation) - Mean revertant colony counts

	TA 1535			TA 1537			TA 98
Conc. (µg/plate)	- MA	+ MA	Cytotoxic (yes/no)	- MA	+ MA	Cytotoxic (yes/no)	- MA	+ MA	Cytotoxic (yes/no)
0*	28	22	No	5	8	No	25	38	No
312.5	31	29	No (Mp)	7	10	No (Mp)	24	32	No (Mp)
625	38	35	No (Mp)	8	9	No (Mp)	26	25	No (Mp)
1250	32	24	No (Sp/Mp)	9	8	No (Mp)	27	29	No (Mp)
2500	36	15	No (Sp)	10	9	No (Sp)	18	29	No (Sp)
5000	34	19	No (Sp)	4	6	No (Sp)	16	29	No (Sp)
Positive control	668	188	No	352	128	No	161	1287	No

 

	TA 100			TA 102
Conc. (µg/plate)	- MA	+ MA	Cytotoxic (yes/no)	- MA	+ MA	Cytotoxic (yes/no)
0*	120	138	No	388	480	No
312.5	118	141	No (Mp)	330	405	No (Mp)
625	123	129	No (Mp)	449	378	No (Mp)
1250	104	115	No (Mp)	405	380	No (Mp)
2500	113	123	No (Sp)	422	406	No (Sp)
5000	126	109	No (Sp)	497	208	No (Sp)
Positive control	604	567	No	2129	3775	No

*solvent control with DMSO

Mp : Moderate precipitate

Sp : Strong precipitate

MA : Metabolic activation

 

Table 3: Second experiment (direct plate incorporation without S9 mix and preincubation with S9 mix) - Mean revertant colony count

	TA 1535			TA 1537			TA 98
Conc. (µg/plate)	- MA	+ MA	Cytotoxic (yes/no)	- MA	+ MA	Cytotoxic (yes/no)	- MA	+ MA	Cytotoxic (yes/no)
0*	11	7	No	5	7	No	25	21	No
312.5	12	11	No (Mp)	3	6	No (Mp)	29	44	No (Mp)
625	10	17	No (Mp)	5	10	No (Mp)	40	33	No (Mp)
1250	10	18	No (Sp/Mp)	4	10	No (Sp/Mp)	29	39	No (Sp/Mp)
2500	15	13	No (Sp)	8	4	No (Sp)	37	69	No (Sp)
5000	9	13	No (Sp)	5	6	No (Sp)	21	21	No (Sp)
Positive control	593	153	No	1443	148	No	303	1377	No

 

	TA 100			TA 102
Conc. (µg/plate)	- MA	+ MA	Cytotoxic (yes/no)	- MA	+ MA	Cytotoxic (yes/no)
0*	127	136	No	341	551	No
312.5	123	150	No (Mp)	275	454	No (Mp)
625	140	164	No (Mp)	362	569	No (Mp)
1250	131	135	No (Sp/Mp)	338	508	No (Sp/Mp)
2500	152	108	No (Sp)	344	523	No (Sp)
5000	146	101	No (Sp)	279	233	No (Sp)
Positive control	655	712	No	1907	1682	No

*solvent control with DMSO

Mp : Moderate precipitate

Sp : Strong precipitate

MA : Metabolic activation

Table 4: Third experiment (preincubation with S9 mix) - Mean revertant colony count

	TA 98
Conc. (µg/plate)	- MA	+ MA	Cytotoxic (yes/no)
0*	-	21	No
312.5	-	16	No (Mp)
625	-	22	No (Mp)
1250	-	21	No (Sp)
2500	-	23	No (Sp)
5000	-	23	No (Sp)
Positive control	-	1342	No

*solvent control with DMSO

Mp : Moderate precipitate

Sp : Strong precipitate

MA : Metabolic activation

 

Applicant's summary and conclusion

Conclusions:

Interpretation of results: negative

Under the experimental conditions, the test material did not show any mutagenic activity in the bacterial reverse mutation test with Salmonella typhimurium.

Executive summary:

The objective of this study was to evaluate the potential of the test material to induce reverse gene mutations in Salmonella typhimurium in accordance with the standardised guidelines OECD 471 and EU Method B13/14.

 

The test material was tested with and without a metabolic activation system (S9 mix, prepared from a liver post mitochondrial fraction (S9 fraction) of rats induced with Aroclor 1254).

S. typhimurium TA 1535, TA 1537, TA 98, TA 100 and TA 102 were used. Each strain was exposed to at least five dose-levels of the test material (three plates/dose-level) ranging from 312.5 to 5000 µg/plate. After 48 to 72 hours of incubation at 37 °C, the revertant colonies were scored. Solvent control (DMSO) and positive controls were used.

 

The numbers of revertants for the vehicle and positive controls were within the ranges specified in the acceptance criteria. The study was therefore considered valid.

A moderate to strong precipitate was observed in the Petri plates when scoring the revertants at dose-levels ≥ 312.5 µg/plate. No noteworthy toxicity was induced in any of the five tester strains.

The test item did not induce any noteworthy increase in the number of revertants which could be considered as relevant, either with or without S9 mix, in any of the five tester strains.

Under these experimental conditions, the test material did not show any mutagenic activity in the bacterial reverse mutation test with Salmonella typhimurium.