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Toxicological information

Genetic toxicity: in vitro

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Administrative data

Endpoint:
in vitro cytogenicity / chromosome aberration study in mammalian cells
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
comparable to guideline study with acceptable restrictions
Cross-reference
Reason / purpose for cross-reference:
reference to same study
Reference
Endpoint:
in vitro gene mutation study in bacteria
Type of information:
experimental study
Adequacy of study:
weight of evidence
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
test procedure in accordance with national standard methods with acceptable restrictions
Qualifier:
equivalent or similar to guideline
Guideline:
OECD Guideline 471 (Bacterial Reverse Mutation Assay)
Deviations:
yes
Remarks:
only 4 strains tested, information on bacterial cultures, substance preparation/storage insufficient
GLP compliance:
not specified
Type of assay:
bacterial reverse mutation assay
Specific details on test material used for the study:
- Name of test material (as cited in study report): sodium azide
- Substance type: powder
- Source of test material: Radian Corporation, Austin, TX.
- Physical state: solid
- Analytical purity: >99%
- Impurities (identity and concentrations): no data
- Composition of test material, percentage of components: no data
- Purity test date: no data
- Lot/batch No.: 32880
- Expiration date of the lot/batch: no data
- Stability under test conditions: Sodium azide was stable as a bulk chemical for at least 2 weeks at up to 60°C when protected from light.
- Storage condition of test material: Stored at room temperature in the dark.
Target gene:
hisitidine
Species / strain / cell type:
S. typhimurium TA 1535, TA 1537, TA 98 and TA 100
Additional strain / cell type characteristics:
not specified
Metabolic activation:
with and without
Metabolic activation system:
S9 mix (from Arochlor 1254-induced male Sprague Dawley rat or Syrian hamster liver)
Test concentrations with justification for top dose:
0.03 / 0.1 / 0.3 / 1.0 / 3.3 / 10.0 / 33.3 µg/plate
Vehicle / solvent:
- Vehicle(s)/solvent(s) used: buffer
- Justification for choice of solvent/vehicle: not given
Untreated negative controls:
yes
Negative solvent / vehicle controls:
yes
Positive controls:
yes
Positive control substance:
other: 4-nitro-o-phenylendiamine (TA98), sodium azide (TA100 and TA1535), 9-aminoacridine (TA1537)
Remarks:
without metabolic activation
Untreated negative controls:
yes
Negative solvent / vehicle controls:
yes
Positive controls:
yes
Positive control substance:
other: 2-aminoanthracene
Remarks:
with metabolic activation
Details on test system and experimental conditions:
METHOD OF APPLICATION: in buffer or S9-mix

DURATION
- Preincubation period:
- Exposure duration: 20 minutes
- Expression time (cells in growth medium): 48h
- Selection time (if incubation with a selection agent):
- Fixation time (start of exposure up to fixation or harvest of cells):

Evaluation criteria:
no data
Statistics:
no data
Species / strain:
S. typhimurium TA 1535, TA 1537, TA 98 and TA 100
Metabolic activation:
with and without
Genotoxicity:
positive
Cytotoxicity / choice of top concentrations:
not specified
Vehicle controls validity:
valid
Positive controls validity:
valid
Species / strain:
S. typhimurium TA 1535, TA 1537, TA 98 and TA 100
Metabolic activation:
with and without
Genotoxicity:
negative
Cytotoxicity / choice of top concentrations:
not specified
Vehicle controls validity:
valid
Positive controls validity:
valid
Additional information on results:
no data
Remarks on result:
other: strain/cell type: TA100, TA1535
Remarks:
Migrated from field 'Test system'.

Table 1: Mutagenicity of sodium azide in Salmonella thyphimurium

Stain Dose (µg/plate) Revertants / plate a
- S9mix + 10% hamster S9 + 10% rat S9
Trial 1 Trial 2   Trial 1 Trial 2   Trial 1 Trial 2
TA100 0 102±5.3 112±1.7 108±9.7 115±8.2 111±8.1
0.03 167±20
0.1 255±9.2
0.3 446±11.7 137±11.3 88±3.3 114±4.2 122±5.2
1 175±2.1 127±1.5 123±0.3 140±5.8
3.3 755±10.3 3.6±14.2 276±17.2 290±10.7 293±11.5
10 1083±19.7 1011±35.6 817±37 929±58.8 951±44.7
33.3 1313±10.7 1124±38.6 1363±8.8 1390±49.1
Trial summary Positive Positive Positive Positive Positive
Positive control 526±12 1006±58 1278±34.7 593±4.4 627±18.2
TA1535 0 20±2.6 25±3.1 13±2 10±0.7 9±2.9 9±0.9
0.03 119±8.4
0.1 247±7.7
0.3 296±12 474±16.3 33±2.5 16±3.8 24±2.9 28±8.8
1 5.8±25.5 78±3.7 45±4.4 77±14.1 50±4.5
3.3 818±40.4 688±28.8 262±5.1 161±13 290±34.3 251±5.8
10 1147±53.6 957±62.1 927±21.8 795±3.2 928±8.4 899±29.6
33.3 1403±34.2 1335±24.1 1317±40.4 1325±36.1 1320±64.1
Trial summary Positive Positive Positive Positive Positive Positive
Positive control 512±18.9 444±17 400±19.3 300±6.3 311±6.4 374±12.8
TA1537 0 8±1 15±1.2 13±3.2
0.3 11±1 24±2.6 15±12
1 8±0.7 22±2.8 8±2.3
3.3 8±0.9 17±4.9 9±2.2
10 9±1.7 13±0.6 9±2.5
33.3 10±1.8 16±1.2 10±2.4
Trial summary Negative Negative Negative
Positive control 119±225 376±12 493±132.1
TA98 0 46±2.4 53±3.4 60±5
0.3 41±6.9 27±1.8 65±8
1 45±72 31±5.8 54±3.9
3.3 52±6.7 31±3.5 62±6.5
10 51±6.9 26±2.9 51±7.2
33.3 54±2.8 30±0.3 59±4.2
Trial summary Negative Negative Negative
Positive control 850±18 1170±9.5 509±20.5

a Revertants are presented as mean ± the standard error from three plates.

Conclusions:
Sodium azide (dose range of 0.03 to 33.3 µg/plate) produced a strong, dose-related increase in mutant colonies in Salmonella thyphimurium strains TA100 and TA1535 when tested in a preincubation protocol with/without Aroclor1254-induced male Sprague-Dawley rat or Syrian hamster liver S9; no mutagenic activity was observed in strains TA1537 or TA98 with/without S9.
Executive summary:

Sodium azide was nominated by the National Cancer Institute for evaluation of its carcinogenic activity because of the high potential for human exposure and the lack of adequate carcinogenicity testing. Besides subacute, subchronic acid chronic in vivo studies in rats, the genetic toxicity was evaluated by testing the ability of the chemical to induce mutations in various strains of Salmonella thyphimurium. 

Sodium azide (dose range of 0.03 to 33.3 µg/plate) produced a strong, dose-related increase in mutant colonies in S. thyphimurium strains TA100 and TA1535 when tested in a preincubation protocol with/without Aroclor1254-induced male Sprague-Dawley rat or Syrian hamster liver S9; no mutagenic activity was observed in strains TA1537 or TA98 with/without S9.

Data source

Reference
Reference Type:
publication
Title:
NTP technical report on the toxicology and carcinogenesis studies of sodium azide (CAS No. 26628-22-8) in F344/N rats (gavage studies)
Author:
National Toxicology Program
Year:
1991
Bibliographic source:
National Toxicology Program Tech. Rep. Ser. 389, 1-165.

Materials and methods

Test guideline
Qualifier:
equivalent or similar to guideline
Guideline:
OECD Guideline 473 (In Vitro Mammalian Chromosome Aberration Test)
Deviations:
not specified
GLP compliance:
not specified
Type of assay:
in vitro mammalian chromosome aberration test

Test material

Constituent 1
Chemical structure
Reference substance name:
Sodium azide
EC Number:
247-852-1
EC Name:
Sodium azide
Cas Number:
26628-22-8
Molecular formula:
N3Na
IUPAC Name:
sodium azide

Method

Target gene:
no data
Species / strain
Species / strain / cell type:
Chinese hamster Ovary (CHO)
Details on mammalian cell type (if applicable):
- Type and identity of media: McCoy's 5A medium
- Properly maintained: no data on supplementation (FBS, antibiotics)
- Periodically checked for Mycoplasma contamination: no data
- Periodically checked for karyotype stability: no data
- Periodically "cleansed" against high spontaneous background: no data
Metabolic activation:
with and without
Metabolic activation system:
S9 mix from Aroclor 1254 induced Sprague-Dawley rat liver
Test concentrations with justification for top dose:
20 / 30 / 40 µg/mL (- S9)
2020 / 3015 / 4020 µg/mL (+ S9)
Vehicle / solvent:
cell culture medium
Controls
Negative solvent / vehicle controls:
yes
Remarks:
cell culture medium
Positive controls:
yes
Positive control substance:
other: Mitomycin-C (- S9); Cyclophosphamid (+ S9)
Details on test system and experimental conditions:
no data
Evaluation criteria:
no data
Statistics:
no data

Results and discussion

Test results
Species / strain:
Chinese hamster Ovary (CHO)
Metabolic activation:
with and without
Genotoxicity:
negative
Cytotoxicity / choice of top concentrations:
not determined
Vehicle controls validity:
valid
Positive controls validity:
valid
Additional information on results:
no data
Remarks on result:
other: all strains/cell types tested
Remarks:
Migrated from field 'Test system'.

Applicant's summary and conclusion

Conclusions:
No induction of chromosomal aberrations occurred in Chinese hamster ovary cells after exposure to sodium azide with or without S9; delayed harvest was used in the trial without S9 to ensure adequate cells for analysis.
Executive summary:

Sodium azide was nominated by the National Cancer Institute for evaluation of its carcinogenic activity because of the high potential for human exposure and the lack of adequate carcinogenicity testing. Besides subacute, subchronic and chronic in vivo studies in rats, the genetic toxicity was evaluated by testing the ability of the chemical to induce chromosomal aberrations in Chinese hamster ovary (CHO) cells. No induction of chromosomal aberrations occurred in CHO cells after exposure to sodium azide with or without S9; delayed harvest was used in the trial without S9 to ensure adequate cells for analysis.