Sodium azide

Short-term toxicity to aquatic invertebrates

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

short-term toxicity to aquatic invertebrates

Type of information:

experimental study

Adequacy of study:

weight of evidence

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

study well documented, meets generally accepted scientific principles, acceptable for assessment

Qualifier:

no guideline followed

Principles of method if other than guideline:

Paracentrotus lividus embryos were exposed to sodium azide (1 µM to 1 mM) throughout development (48 hr) in filtered seawater and checked for developmental defects.

GLP compliance:

no

Analytical monitoring:

not specified

Vehicle:

no

Test organisms (species):

other: Paracentrotus lividus

Details on test organisms:

Gametes and embryos from the Mediterranean sea urchin Paracentrotus lividus were obtained and reared. Natural filtered seawater (fsw) was used throughout the experiments, for gamete suspension and embryo culture media.

Test type:

static

Water media type:

saltwater

Limit test:

no

Total exposure duration:

48 h

Hardness:

no data

Test temperature:

20°C

pH:

8.0 - 8.5

Dissolved oxygen:

no data

Salinity:

no data

Nominal and measured concentrations:

1 µmol/L - 1 mmol/L

Reference substance (positive control):

yes

Remarks:

NaH2AsO4, Na2CrO4

Duration:

48 h

Dose descriptor:

LOEC

Effect conc.:

ca. 10 µmol/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

morphology

Remarks:

Thickening of gut wall

Duration:

48 h

Dose descriptor:

NOEC

Effect conc.:

ca. 1 µmol/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

morphology

Remarks:

thickening of gut wall

Details on results:

When P. lividus embryos were exposed to sodium azide throughout development (48 hr), at levels ranging from 1 µM to 1 mM, at normal pH (8.5 to 8.0), a dose-dependent increase was observed in gut malformations. No effects were induced by NaCl up to 10 mM (added to natural seawater).
Sodium azide induced a progressive thickening of digestive tract lining, ending in complete filling of gut in the most severely affected larvae. Neither a relevant increase in skeletal malformations, nor in pre-pluteus pathological larvae (P2) was detected in exposed cultures, up to 100 µM sodium azide. However, when sodium azide levels were raised from 100µM to 1 mM, a 48-hr exposure of embryos throughout development caused retardation in skeletal differentiation, resulting in approximately 40% inhibited plutei (size: <50% normal plutei) in addition to pathologic (gut) plutei.

Cytogenetic analysis on cleaving embryos in four experiments failed to reveal any changes in mitotic aberration frequencies or in metaphase/anaphase ratio (M/A) in sodium azide-exposed embryos, as shown in Table 1. The mean number of mitoses per embryo (MPE) was slightly decreased in 1 mM sodium azide, thus indicating a weak mitotoxicity at the highest sodium azide level. Among the positive controls, As(V) displayed a slight increase in MPE, whereas Cr(VI) both showed mitotoxicity (decreased MPE) and spindle damage (by a significant M/A increase).

Table 1: Cytogenetic Parameters in Embryos Exposed Throughout Cleavage to SA or Positive Control Inorganics.

Treatment schedule	MPE ± SE	M/A	TMA
Control	31.3 ± 0.9	1.3	1.7
100 µM sodium azide	31.1 ± 0.8	1.2	1.5
1 mM sodium azide	27.5 ± 1.0 *	1.6	1.7
10 µM NaH2As04	34.7 + 0.8 *	1.4	1.1
100 µM Na2Cr04	24.0 + 1.6 *	3.6 **	1.1

 Mitotic aberrations are reported as total mitotic aberrations (TMA); quantitative parameters: mean no. mitoses per embryo (MPE) ± SE and metaphase/anaphase ratio (M/A). Data from 50-embryo samples per schedule.

*P <0.001, as determined by t-test.

**P <0.02, as determined bychi²test.

Validity criteria fulfilled:

yes

Conclusions:

The LOEC of sodium azide to sea urchins after 48h incubation is 10 µmol/L. Observed effects consisted mainly of developmental gut abnormalities of the azide exposed embryos.

Executive summary:

 Sodium azide was tested on sea urchin embryos and gametes (Paracentrotus lividus). Developing embryos were exposed to sodium azide (1 µM to 1 mM) up to pluteus larval stage (48h, in seawater). Developmental defects in sodium azide-exposed embryos consisted mainly of gut abnormalities, showing a concentration-dependent increase with a LOEC of 10 µM. Sodium azide-induced damage to gut was exerted during gastrulation, as evident by lectin binding of extracellular matrix. No mitotic damage was observed in sodium azide-exposed embryos.

This study is classified as reliable with restrictions.

Results Synopsis: 

Test Organism Age: embryos

Test Type: unknown

NOEC (48 h): ca. 1 µmol/L (0.065 mg/L)

LOEC (48 h): ca. 10 µmol/L (0.65 mg/L)

Endpoints effected: developmental gut abnormalities

Reference 2

Endpoint:

short-term toxicity to aquatic invertebrates

Type of information:

other: Handbook data

Adequacy of study:

weight of evidence

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

data from handbook or collection of data

Principles of method if other than guideline:

Handling of test organisms and procedures for static toxicity tests followed those described by Lennon and Walker (1964) and Macek and McAllister (1970), and conform well with those recommended by Brauhn and Schoettger (1975) and the Committee on Methods for Toxicity Tests with Aquatic Organisms (1975).

GLP compliance:

not specified

Specific details on test material used for the study:

- Chemical name: sodium azide
- Alternative names: Kazoe, Smite
- Sample description: sodium azide 98 %

Analytical monitoring:

no

Details on sampling:

Sampling method: Stock solutions were prepared immediately before each test.

Vehicle:

yes

Remarks:

Commercial grade acetone was used as the carrier solvent. Occasionally, ethanol or dimethylform amide was substituted. Solvent concentrations did not exceed 0.5 mL/L in final dilution water.

Details on test solutions:

Test water (dilution water) was reconstituted from deionized water of at least 10E+6 ohms resistivity by the addition of appropriate reagent grade chemicals. When purity of test chemicals was known, all calculated concentrations were based on percent active ingredients.

Test organisms (species):

Gammarus fasciatus

Details on test organisms:

TEST ORGANISM
- Common name: Freshwater shrimp
First instar stage of life cycle
Original stocks of invertebrates were collected and cultured from wild populations with no known source of contamination; these populations were replenished regularly. The invertebrates were cultured in the laboratory by methods similar to those described by Sanders and Cope (1966).

Test type:

static

Limit test:

no

Total exposure duration:

48 h

Remarks on exposure duration:

Immobilization tests with invertebrates were conducted for 48 h.

Post exposure observation period:

no data

Hardness:

40 to 50 mg/L as CaCO3

Test temperature:

15 °C

pH:

7.2 to 7.5

Dissolved oxygen:

no data

Conductivity:

at least 10^6 ohms

Nominal and measured concentrations:

At least six concentrations were used per toxicity test; however, specific concentrations were not provided.

Details on test conditions:

Invertebrates were acclimated from well water to dilution water over a 4- to 6-h period. Test chambers varied in size for invertebrates, depending on the species used; volume of test solution ranged from 0.25 to 4 liters. At least 10 organisms were exposed to each concentration for all definitive tests. The tests began upon initial exposure to the toxicant. Immobilization tests with invertebrates were conducted for only 48 h. The number of dead or affected organisms in each test chamber was recorded and the dead organisms were removed every 24 h; general observations on the condition of test organisms were also recorded at these times.

Reference substance (positive control):

not specified

Key result

Duration:

48 h

Dose descriptor:

LC50

Effect conc.:

5 mg/L

Basis for effect:

mobility

Remarks on result:

other: 95 % CI = 3.7-6.8

Reported statistics and error estimates:

Toxicity data were analyzed by a statistical method described by Litchfield and Wilcoxon (1949) to determine the LC50 (theoretical estimate of the concentration lethal to 50 % of the test animals) and 95 % confidence intervals.

Validity criteria fulfilled:

not applicable

Conclusions:

The LC50 for Gammarus fasciatus after 48 h exposure to sodium azide was 5.0 mg/L (95 % CI = 3.7–6.8 mg/L).

Executive summary:

The 48–hr acute toxicity of Sodium azide to Gammarus fasciatus was studied under static conditions. Mortality and immobilization were observed.  The 48–hour LC₅₀was 5.0 mg a.i./L. The sublethal effects included were immobility but these effects were not statistically evaluated.

Based on the results of this study, Sodium azide would  be classified as Chronic Aquatic Cat. 2 to G. fasciatus in accordance with the Regulation (EC) No 1272/2008 (CLP Regulation).

This study is classified as supplementary, because methodological data are not complete (data from handbook).

 

Results Synopsis

Test Organism Age: 1^stinstar

Test Type: static

 

LC₅₀/ EC₅₀ : 5.0 mg a.i./L                             95% C.I.:  3.7 to 6.8 mg a.i./L

Endpoint(s) Effected:  mortality

Reference 3

Endpoint:

short-term toxicity to aquatic invertebrates

Type of information:

other: Handbook data

Adequacy of study:

weight of evidence

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

data from handbook or collection of data

Principles of method if other than guideline:

According to Lennon and Walker (1964), Macek and McAllister (1970), Brauhn and Schoettger (1975), Commitee on Methods for Toxicity Tests with Aquatic Organisms (1975).

GLP compliance:

not specified

Analytical monitoring:

not specified

Details on sampling:

no data

Vehicle:

not specified

Details on test solutions:

Acetone was used as carrier solvent. Final concentrations of solvent in test media did not exceed 0.5 ml/L.

Test organisms (species):

Daphnia pulex

Details on test organisms:

TEST ORGANISM
- Common name: water flea

Test type:

static

Water media type:

not specified

Limit test:

no

Total exposure duration:

48 h

Post exposure observation period:

no data

Hardness:

40-50 mg/L CaCO3

Test temperature:

15 °C

pH:

7.2 - 7.5

Dissolved oxygen:

no data

Salinity:

no data

Nominal and measured concentrations:

no data

Details on test conditions:

no data

Reference substance (positive control):

not specified

Key result

Duration:

48 h

Dose descriptor:

LC50

Effect conc.:

4.2 mg/L

Basis for effect:

mortality

Remarks on result:

other: CL: 2.8-6.2

Details on results:

no data

Results with reference substance (positive control):

no data

Reported statistics and error estimates:

no data

Validity criteria fulfilled:

not specified

Conclusions:

The LC50 (Daphnia pulex) after 48h exposure to sodium azide was 4.2 mg/L.

Executive summary:

The 48 –hr-acute toxicity of sodium azide to Daphnia pulex was studied under static conditions.  Mortality and immobilization were observed.  The 48 – hour LC50/EC₅₀was 4.2 mg/L. The sublethal effects included were immobility but were not statistically evaluated or presented.

Based on the results of this study, sodium azide would  be classified as Chronic Aquatic Cat. 2 to D. pulex in accordance with the Regulation (EC) No 1272/2008 (CLP Regulation).

This study is classified as supplementary, because methodological data are not complete (data from handbook).

 

Results Synopsis

 

Test Organism Age: 1^stinstar

Test Type: static

 

LC50 / EC₅₀ : 4.2 mg/L                     95% C.I.:  2.8 to 6.2 mg/L

Endpoint(s) Effected:  mortality

Reference 4

Endpoint:

short-term toxicity to aquatic invertebrates

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

Remarks:

This experiment was part of a larger multi-year study by the State Water Resources Control Board of California. It included multiple species, test conditions, and chemicals. The entire body of work went through extensive peer review. The body of evidence from this multi-year study adds to the reliability of this single study.

Qualifier:

according to guideline

Guideline:

other: EPA/600/R-95-136: Short-term methods for estimating the chronic toxicity of effluents and receiving waters to west coast marine and estuarine organisms

Version / remarks:

In the present study, both length and weight were measured.

Principles of method if other than guideline:

This guideline describes a 7-day semi-static toxicity test using growth and survival of juvenile mysids to determine the toxicity of substances in marine waters. The study endpoints are survival and growth.

GLP compliance:

no

Analytical monitoring:

no

Details on sampling:

no data

Vehicle:

no

Details on test solutions:

no data

Test organisms (species):

other aquatic crustacea: Holmesimysis costata

Details on test organisms:

TEST ORGANISM
- Common name: opossum shrimp
- Source: wild caught
- Age at study initiation (mean and range, SD): 3-4 d
- Weight at study initiation (mean and range, SD): no data
- Length at study initiation (length definition, mean, range and SD): no data
- Method of breeding: Gravid females were isolated in the laboratory and placed in a screened compartment within a larger aquarium. Juveniles were collected the following day (day 0) by removing the adults (in the screened compartment) and siphoning the juveniles into another container.
- Feeding during test
- Food type: Artemianauplii and finely ground Tetramin® flake food. Feeding rate was adjusted daily for mortality.


ACCLIMATION
- Acclimation period: 3-4 days
- Acclimation conditions (same as test or not): yes
- Type and amount of food: Artemianauplii and finely ground Tetramin® flake food
- Feeding frequency: no data
- Health during acclimation (any mortality observed): no data

Test type:

semi-static

Water media type:

saltwater

Limit test:

no

Total exposure duration:

7 d

Post exposure observation period:

no data

Hardness:

no data

Test temperature:

12 ± 2 °C

pH:

no data

Dissolved oxygen:

60-100 % saturation

Salinity:

33 ± 2 %

Nominal and measured concentrations:

0 (control), 10, 18, 32, 56, 100, and 320 µg/L

Details on test conditions:

TEST SYSTEM
- Test vessel:
- fill volume: 200 mL
- Aeration: yes
- Renewal rate of test solution (frequency/flow rate):water renewal at 48 and 96 h by replacing 75 % of the test solution volume.
- No. of organisms per vessel: 5
- No. of vessels per concentration (replicates): 5
- No. of vessels per control (replicates): 5

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: sea water
- Culture medium different from test medium: yes
- Intervals of water quality measurement:


OTHER TEST CONDITIONS
- Adjustment of pH: no
- Photoperiod: 16h light, 8h dark
- Light intensity: 100 lux


EFFECT PARAMETERS MEASURED (with observation intervals if applicable) : survival and growth (length and mass)


TEST CONCENTRATIONS
- Spacing factor for test concentrations: ca. 1.75 (except for the highest concentration which is 3.2)
- Range finding study: yes
- Results used to determine the conditions for the definitive study: yes

Reference substance (positive control):

no

Duration:

7 d

Dose descriptor:

NOEC

Effect conc.:

100 µg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mortality

Key result

Duration:

7 d

Dose descriptor:

LC50

Effect conc.:

149 µg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mortality

Details on results:

no data

Results with reference substance (positive control):

no data

Reported statistics and error estimates:

no data

Validity criteria fulfilled:

not specified

Conclusions:

The short-term acute toxicity test with sodium azide on marine mysid crustaceae Holmesimysis costata revealed a 7-d NOEC of 100 µg/L and a LC50 of 149 µg/L. The aquatic toxicity of sodium azide was assessed using a short-term test on marine mysid crustaceae Holmesimysis costata, according to guideline EPA/600/R-95-136 of the U.S. EPA. Three tests were conducted, two range finding tests and a definitive test with more closely spaced toxicant concentrations. Nominal sodium azide concentrations in the definitive test were 0 (control), 10, 18, 32, 56, 100, and 320 µg/L. Test parameters were survival and growth (mass and length).
Mysids were particularly sensitive to sodium azide. However, sodium azide did not significantly inhibit mysid growth at concentrations below those causing significant mortality. Two preliminary tests with azide found 100% mortality in the low milligram per liter and mid to high microgram per liter range. A third test with concentrations more closely spaced in the 10 to 320 µg/L range resulted in an NOEC of 100 µg/L and an LC50 of 149 µg/L.

Executive summary:

The 7-d toxicity of sodium azide to Holmesimysis costata (opossum shrimp) was studied under semi-static conditions. Mysids were exposed to 0 (control), 10, 18, 32, 56, 100, and 320 µg/L for 7 days. Mortality was recorded daily. The 7-d LC₅₀ was 149 µg/L. The 7-d NOEC based on mortality was 100 µg/L.

 

Based on the results of this study, sodium azide would be classified as Chronic Aquatic Cat. 1 and Acute Aquatic Cat. 1 to H. costata in accordance with the Regulation (EC) No 1272/2008 (CLP Regulation). 

This study is classified as acceptable and satisfies the guideline requirements for an acute toxicity study with freshwater invertebrates.

 

Results Synopsis

 

Test Organism Age: 3-4 d

Test Type: semi-static

 

LC₅₀:  149 µg/L                           

NOEC:  100 µg/L        

               

Endpoint(s) Effected:  mortality

Reference 5

Endpoint:

short-term toxicity to aquatic invertebrates

Type of information:

experimental study

Adequacy of study:

weight of evidence

Reliability:

3 (not reliable)

Rationale for reliability incl. deficiencies:

significant methodological deficiencies

Qualifier:

equivalent or similar to guideline

Guideline:

other: ASTM standard E729-80

Principles of method if other than guideline:

Acute aquatic toxicity test on wild-caught rusty crayfish.
Crayfish were collected from the wild and were held at least 2 weeks before they were tested. Nineteen chemicals were tested as potential control agents on the basis of their previous use in fisheries or their suspected toxicity to and selectivity for crayfish. Laboratory tests were conducted in 19-L glass or stainless steel vessels containing 15 L of soft reconstituted well water at 12°C, according to the methods outlined by the Committee on Methods for Toxicity Tests with Aquatic Organisms (1975) and ASTM (1980). Ten crayfish were exposed to each concentration of a chemical, and deaths were recorded daily for 96h. Immobile crayfish were considered dead if they did not respond to probing with a glass rod.

GLP compliance:

no

Analytical monitoring:

no

Details on sampling:

no data

Vehicle:

no

Details on test solutions:

no data

Test organisms (species):

other aquatic crustacea: Orconectes rusticus

Details on test organisms:

TEST ORGANISM
- Common name: rusty crayfish

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

96 h

Post exposure observation period:

no data

Hardness:

256 CaCO3 (mg/L)

Test temperature:

12 °C

pH:

ca 7.98

Dissolved oxygen:

no data

Salinity:

no data

Nominal and measured concentrations:

no data

Details on test conditions:

no data

Reference substance (positive control):

no

Key result

Duration:

96 h

Dose descriptor:

LC100

Effect conc.:

1 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mortality

Details on results:

no data

Results with reference substance (positive control):

no data

Reported statistics and error estimates:

no data

Validity criteria fulfilled:

not specified

Conclusions:

The LC100 (Orconectes rusticus, 96h) was 1.0 mg/L in fresh water.

Executive summary:

The 96–hr acute toxicity of sodium azide to Orconectes rusticus (rusty crayfish) was studied under static conditions. Mortality was observed.  The 96 – hour LC₁₀₀was 1.0 mg sodium azide/L.

Based on the results of this study, sodium azide would be classified as Chronic Aquatic Cat. 1 and Acute Aquatic Cat. 1 to O. rusticus in accordance with the Regulation (EC) No 1272/2008 (CLP Regulation).

This study is classified as supplementary, because the documentation is insufficient.

 

Results Synopsis

 

Test Type: static

 

LC₁₀₀: 1.0 mg a.i./L         

Endpoint(s) Effected:  mortality

Reference 6

Endpoint:

short-term toxicity to aquatic invertebrates

Type of information:

experimental study

Adequacy of study:

weight of evidence

Reliability:

4 (not assignable)

Rationale for reliability incl. deficiencies:

documentation insufficient for assessment

Qualifier:

no guideline followed

Principles of method if other than guideline:

Red crawfish (Procambarus clarkii) were exposed to sodium azide individually and observations on death were made after each 24h for 96h total exposure duration. Graduated concentrations were used until a maximum of 1 ppm separated the crawfish that lived and the ones that died. These concentrations were verified on at least 5 animals.

GLP compliance:

no

Specific details on test material used for the study:

Technical grade

Analytical monitoring:

no

Details on sampling:

no data

Vehicle:

no

Details on test solutions:

no data

Test organisms (species):

other aquatic crustacea: Procambarus clarkii (Girard)

Details on test organisms:

TEST ORGANISM
- Common name: red crawfish; other names: red swamp crayfish, Louisiana crawfish or Louisiana crayfish
- Strain: no data
- Source: commercial crawfish farm near St. Landry Parish near Cankton, LA
- Age at study initiation (mean and range, SD): no data
- Weight at study initiation (mean and range, SD): 4-10 g
- Length at study initiation (length definition, mean, range and SD): no data
- Method of breeding: no data
- Feeding during test
- Food type: commercial catfish pelletized feed, raw liver, fresh dead fish
- Amount: no data
- Frequency: no data


ACCLIMATION
- Acclimation period: at least 1 week
- Acclimation conditions (same as test or not): 30-gallon aquarium
- Type and amount of food: commercial catfish pelletized water, raw liver, fresh dead fish
- Feeding frequency: no data
- Health during acclimation (any mortality observed): not reported

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

96 h

Post exposure observation period:

none

Hardness:

no data

Test temperature:

25 °C

pH:

no data

Dissolved oxygen:

no data

Salinity:

no data

Nominal and measured concentrations:

1ppm, 0.8 ppm, 0.6 ppm, 0.4 ppm

Details on test conditions:

TEST SYSTEM
- Test vessel:
- Type: open
- Material, size, headspace, fill volume: one-gallon, wide-mouth glass jars lined with a 6 x 3.5 x 15-inch polyethylene bag (replaced after each test)
- Aeration: containers were placed in wooden racks that held the jars at a 30-degree angle. This allowed the crawfish sufficient shallow water to crawl to the surface, thereby eliminating the necessity of aeration.
- Type of flow-through (e.g. peristaltic or proportional diluter): not applicable
- Renewal rate of test solution (frequency/flow rate): not applicable
- No. of organisms per vessel: 1
- No. of vessels per concentration (replicates): at least 5
- No. of vessels per control (replicates): 1 control per every 4 test vessels
- No. of vessels per vehicle control (replicates): not applicable
- Biomass loading rate: 4-10 g/L, calculated from the values reported (crawfish weight 4-10 g, test vessel size: 1L)


TEST MEDIUM / WATER PARAMETERS
- Sourceof dilution water: Water from Bayou De Siard, a 1215-acre lake adjacent to the laboratory
- Total organic carbon: no data
- Particulate matter:no data
- Metals:no data
- Pesticides:no data
- Chlorine:no data
- Alkalinity:no data
- Ca/mg ratio:no data
- Conductivity:no data
- Intervals of water quality measurement: no data


OTHER TEST CONDITIONS
- Adjustment of pH:no data
- Photoperiod:no data
- Light intensity:no data


EFFECT PARAMETERS MEASURED (with observation intervals if applicable) : mortality, observation interval: every 24h


TEST CONCENTRATIONS
- Spacing factor for test concentrations: 2
- Justification for using less concentrations than requested by guideline:
- Range finding study: conducted, but not reported
- Test concentrations: not reported
- Results used to determine the conditions for the definitive study:not reported

Reference substance (positive control):

no

Duration:

96 h

Dose descriptor:

NOEC

Effect conc.:

<= 0.4 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

behaviour

Remarks:

autotomy

Duration:

96 h

Dose descriptor:

NOEC

Effect conc.:

0.4 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mortality

Duration:

96 h

Dose descriptor:

LC100

Effect conc.:

0.6 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mortality

Duration:

96 h

Dose descriptor:

EC50

Effect conc.:

>= 0.4 - < 0.6 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mortality

Remarks on result:

not determinable because of methodological limitations

Details on results:

Two formulations of sodium azide were tested. The granular formulation was slightly less toxic to crawfish than the technical formulation. When the mud was added to the containers of both formulations, the toxicities were the same. These toxicities closely agreed with that for the technical sodium azide without mud.
Crawfish that were exposed to sub-lethal concentrations of sodium azide exhibited some irritation. Most of the crawfish held in concentrations of sodium azide from 0.4 ppm to 1 ppm would exhibit autotomy.

Results for 48h and 96h were the same.

Results with reference substance (positive control):

no reference substance used

Reported statistics and error estimates:

no statistic determination reported

Table 1: Results of crawfish bioassays presented in ppm (mg/L).

Observation time	Status	Sodium azide		Sodium azide + mud^a)
		technical	granular	technical	granular
24h	Alive	0.6	0.8	0.8	0.8
	Dead	1.0	1.0	1.0	1.0
48h	Alive	0.4	0.8	0.4	0.4
	Dead	0.6	1.0	0.6	0.6
72h	Alive	0.4	0.8	0.4	0.4
	Dead	0.6	1.0	0.6	0.6
96h	Alive	0.4	0.8	0.4	0.4
	Dead	0.6	1.0	0.6	0.6

^a)Added 50 grams of mud to container

Validity criteria fulfilled:

no

Conclusions:

The supposed LC50 (crawfish, 48h) is in the range of 0.4-0.6 mg/L.

Executive summary:

The 96–hr acute toxicity of sodium azide to Procambarus clarkii (crawfish) was studied under static conditions. Crawfish were exposed to control and test chemical at nominal concentration of 0.4, 0.6, 0.8 and 1 ppm (mg/L) for 96 hr.  Mortality and sublethal effects were observed daily. The 96–hr LC₁₀₀based on mortality was 0.6 mg/L. The NOEC for mortality equals 0.4 mg/L, though autotomy was recorded as sublethal effect at 0.4 mg/L.

 

Based on the results of this study, sodium azide would be classified as Chronic Aquatic Cat. 1 and Acute Aquatic Cat. 1 to P. clarkii in accordance with the Regulation (EC) No 1272/2008 (CLP Regulation). 

This study is classified as supplementary and does not satisfy the guideline requirements for an acute toxicity study with freshwater invertebrates (missing statistics, study design on replicates is not distinct).

 

Results Synopsis

 

Test Organism Age: weight: juvenile, 4 to 10 g

Test Type: static

 

LC₅₀:  not determined

LC100: 0.6 ppm (mg/L)

NOEC:  0.4 ppm (mg/L)

Endpoint(s) Effected: mortality

Reference 7

Endpoint:

short-term toxicity to aquatic invertebrates

Type of information:

other: Handbook data

Adequacy of study:

weight of evidence

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

data from handbook or collection of data

Principles of method if other than guideline:

According to Lennon and Walker (1964), Macek and McAllister (1970), Brauhn and Schoettger (1975), Commitee on Methods for Toxicity Tests with Aquatic Organisms (1975).

GLP compliance:

not specified

Analytical monitoring:

not specified

Details on sampling:

no data

Vehicle:

not specified

Details on test solutions:

Acetone was used as carrier solvent. Final concentrations of solvent in test media did not exceed 0.5 ml/L.

Test organisms (species):

Simocephalus serrulatus

Details on test organisms:

TEST ORGANISM
- Common name: Daphnid/water flea
First instar stage of life cycle
Original stocks of invertebrates were collected and cultured from wild populations with no known source of contamination; these populations were replenished regularly. The invertebrates were cultured in the laboratory by methods similar to those described by Sanders and Cope (1966).

Test type:

static

Water media type:

not specified

Limit test:

no

Total exposure duration:

48 h

Post exposure observation period:

no data

Hardness:

40-50 mg/L CaCO3

Test temperature:

15 °C

pH:

7.2-7.5

Dissolved oxygen:

no data

Salinity:

no data

Nominal and measured concentrations:

no data

Details on test conditions:

no data

Reference substance (positive control):

not specified

Key result

Duration:

48 h

Dose descriptor:

LC50

Effect conc.:

6.4 mg/L

95% CI:

>= 4.6 - <= 8.9

Basis for effect:

mobility

Details on results:

no data

Results with reference substance (positive control):

no data

Reported statistics and error estimates:

Toxicity data were analyzed by a statistical method described by Litchfield and Wilcoxon (1949) to determine the LC50 (theoretical estimate of the concentration lethal to 50 % of the test animals) and 95 % confidence intervals.

Validity criteria fulfilled:

not specified

Executive summary:

The 48-hr acute toxicity of sodium azide to Simocephalus sp. was studied under static conditions. Mortality and immobilization were observed. The 48-hour LC50/EC₅₀ was 6.4 mg/L. The sublethal effects included were immobility but these effets were not statistically evaluated.

Based on the results of this study, Sodium azide would  be classified as Chronic Aquatic Cat. 2 to Simocephalus sp. in accordance with the Regulation (EC) No 1272/2008 (CLP Regulation).

This study is classified as supplementary, because methodological data are not complete (data from handbook).

Results synopsis

Test organism age: 1^stinstar

Test type: Static

LC₅₀: 6.4 mg/L (95 % C.I.: 4.6–8.9 mg/L)

Endpoint(s) effected: Mortality

Description of key information

The LC₅₀ for freshwater aquatic invertebrates range between 0.4 and 6.4 mg/L after 48 h exposure. Species examined were Procambarus clarkii, Daphnia pulex, Simocephalus sp., and Orconectes rusticus. For the marine species Holmesimysis costata a LC₅₀ of 0.15 mg/L was reported after 7 d exposure. The effect concentrations for the sea urchin Paracentrotus lividus were less sensitive. The 48 h LOEC was determined with 6.5 mg/L and the NOEC with 0.65 mg/L.

Five different LC₅₀ values, one LC₁₀₀ and one NOEC were assessed for this weight of evidence approach. Four of seven values were below 1.0 mg/L (the LC100reported from Bills (1988) was 1.0 mg/L, indicating that the corresponding LC50 must be below 1 mg/L). The LC50 values from Johnson (1980) range from 4.2 to 6.4 mg/L.

The range of the LC-values for freshwater invertebrates are between the classifications into Chronic Aquatic Cat. 1 (concerning results from Bills 1998, Hughes 1966, and Hunt 1996) or Cat. 2 (concerning results from Johnson 1980). As data from Johnson 1980 are handbook data, and the experimental conditions are not described in detail, the data from the mentioned peer reviewed publications are consulted for the classification. Hence Sodium azide would be classified as Chronic Aquatic Cat. 1 to aquatic invertebrates in accordance with the CLP classification system.

Study results on marine species (Pagano, 1988 and Hunt, 1997) were not considered for chemical safety assessment, as the envisaged use of the substance does not lead to  release into marine waters. Therefore, the corresponding effect concentrations, albeit lower than freshwater effect concentrations, are not relevant for assessment of environmental hazards of sodium azide. 

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates

Dose descriptor:

EC50

Effect concentration:

400 µg/L

Marine water invertebrates

Marine water invertebrates

Dose descriptor:

LC50

Effect concentration:

150 µg/L