Chlorine dioxide

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:

key study

Reliability:

1 (reliable without restriction)

Qualifier:

according to guideline

Guideline:

EU Method C.2 (Acute Toxicity for Daphnia)

Deviations:

no

GLP compliance:

yes

Remarks:

no GLP certificate was joined

Specific details on test material used for the study:

Details on properties of test surrogate or analogue material (migrated information):
no data

Analytical monitoring:

yes

Details on sampling:

Dissolved oxygen, pH, temperature and test substnace concentration were measured at 0 and 48 h.

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Method: The test solutions of chlorine dioxide were prepared by dissolving volumes of test article stock solution directly to the study beakers in order to obtain the requested concentrations taking into account the strength of the stock solution that was checked weekly by RBM.
- Eluate: The dilution water used was the one suggested by ISO 6341-1982
- Differential loading: no data
- Controls: no data
- Chemical name of vehicle (organic solvent, emulsifier or dispersant): not applicable
- Concentration of vehicle in test medium (stock solution and final test solution): not applicable
- Evidence of undissolved material (e.g. precipitate, surface film, etc): no data

Test organisms (species):

Daphnia magna

Details on test organisms:

TEST ORGANISM
- Common name: Daphnia magna
- Strain: no data
- Source: laboratory breeding
- Age at study initiation (mean and range, SD): not more than 24 hours
- Weight at study initiation (mean and range, SD): no data
- Length at study initiation (length definition, mean, range and SD): no data
- Valve height at study initiation, for shell deposition study (mean and range, SD): no data
- Peripheral shell growth removed prior to test initiation: no data
- Method of breeding: with green algae (S. capricornutum)
- Feeding during test: NO

ACCLIMATION
- Acclimation period: no data
- Acclimation conditions (same as test or not):
- Type and amount of food:
- Feeding frequency: 3 times/wk
- Health during acclimation (any mortality observed):

Test type:

not specified

Water media type:

freshwater

Limit test:

no

Total exposure duration:

48 h

Post exposure observation period:

no data

Hardness:

251 mg/L of CaCO3

Test temperature:

20 °C

pH:

7.1 - 7.5

Dissolved oxygen:

8.0 - 8.7 mg/L

Salinity:

not applicable

Nominal and measured concentrations:

Nominal concentrations: 0.018, 0.032, 0.056, 0.100,0.180 mg/L

Measured concentrations (at t = 0 h): 0, 0.04, 0.06, 0.09 and 0.11 mg/L
Measured concentrations (at t = 48 h): Not determined, 0.02, 0.04, 0.05 and 0.09 mg/L

Details on test conditions:

TEST SYSTEM
- Test vessel: glass vials
- Type (delete if not applicable): open
- Material, size, headspace, fill volume: no data
- Aeration: no data
- 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: 5
- No. of vessels per concentration (replicates): 4
- No. of vessels per control (replicates): 4
- No. of vessels per vehicle control (replicates):not applicable
- Biomass loading rate: no data

OTHER TEST CONDITIONS
- Adjustment of pH: no data
- Photoperiod: 16:8
- Light intensity: no data

TEST CONCENTRATIONS
- Spacing factor for test concentrations: 1.778
- Justification for using less concentrations than requested by guideline: not applicable
- Range finding study
- Test concentrations: 0.018, 0.032, 0.056, 0.1, and 0.18 mg/L of chlorine dioxide (nominal concentrations)
- Results used to determine the conditions for the definitive study: no data

Reference substance (positive control):

no

Duration:

24 h

Dose descriptor:

EC50

Effect conc.:

0.076 mg/L

Nominal / measured:

meas. (not specified)

Conc. based on:

act. ingr.

Basis for effect:

mobility

Remarks on result:

other: 95% confidence limits of 0.068 – 0.086 mg/L

Key result

Duration:

48 h

Dose descriptor:

EC50

Effect conc.:

0.063 mg/L

Nominal / measured:

meas. (not specified)

Conc. based on:

act. ingr.

Basis for effect:

mobility

Remarks on result:

other: 95% confidence limits of 0.048 – 0.084 mg/L

Details on results:

The study was performed taking into account the actual content of the stock solution of chlorine dioxide. The toxicity values can therefore be expressed both as referring to the 100% ClO2 and to the solution at the nominal concentration of 0.2%. The calculated EC50 values of 100% ClO2 at 24 h and 48 h were 0.076 and 0.063 mg/L respectively corresponding to 0.038 and 0.032 g/L of 0.2% solution being 1 g/L its density.

Results with reference substance (positive control):

Not applicable

Reported statistics and error estimates:

The 24 h EC50 was 0.076 mg/L with 95% confidence limits of 0.068 – 0.086 mg/L.
The 48 h EC50 was 0.063 mg/L with 95% confidence limits of 0.048 – 0.084 mg/L.

Table A7_4_1_2(1)-5:        Immobilisation data

Initial measured Concentration (mg/L)	Treated Animals	Immobilized Daphnia			Oxygen (mg/l) 48 h	pH 48 h	Temperature (°C) 48 h
		24 h	48 h	Total %
0.0	20	0	0	0	8.2	7.3	20
0.02	20	0	4	20	8.7	7.3	20
0.04	20	1	6	30	8.5	7.5	20
0.06	20	5	9	45	8.1	7.4	20
0.09	20	9	11	55	8.2	7.3	20
0.11	20	20	20	100	NS	NS	NS

NS = Not stated

Table A7_4_1_2(1)-6:        Effect data

	EC50^1	95 % c.l.	EC0^1	EC100^1
24 h [mg/l]	0.076 (n)	0.068 – 0.086
48 h [mg/l]	0.063 (n)	0.048 – 0.084	0.02	0.11

¹ based on nominal (n) concentrations

Validity criteria fulfilled:

no

Remarks:

No reference substance was tested

Conclusions:

The 48 h EC50 was 0.063 mg/L.

Executive summary:

Daphnia magna were exposed to chlorine dioxide for 48 hours in an acute immobilization test, under GLP and following C.2 EEC Guideline. No animals were immobilized in the control group. EC50(48h) = 0.063 mg/L of 100% ClO2, i.e. 0.032 g/L of 0.2% ClO2 solution being 1 g/L its density.

Reference 2

Endpoint:

short-term toxicity to aquatic invertebrates

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Qualifier:

according to guideline

Guideline:

other: EPA-821-R-02-014

GLP compliance:

not specified

Specific details on test material used for the study:

Details on properties of test surrogate or analogue material (migrated information):
no data

Analytical monitoring:

no

Details on sampling:

- Concentrations: 0, 0.01, 0.1, 1.0, 10, and 100 mg/L
- Sampling method: test concentrations were verified at the beginning of the test using HACH DPD Method 10126
- Sample storage conditions before analysis: no data

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Method: A stock solution was made from powered product supplied by Ecochlor. Two separate powders were mixed according to directions by dissolving them in deionized water and bringing the volume to one liter to obtain a target concentration of 3000 ppm chlorine dioxide.
- Eluate: deionized water
- Differential loading: 0.1 X dilution series
- Controls: only seawater
- Chemical name of vehicle (organic solvent, emulsifier or dispersant): not applicable
- Concentration of vehicle in test medium (stock solution and final test solution(s) including control(s)): not applicable
- Evidence of undissolved material (e.g. precipitate, surface film, etc): no data

Test organisms (species):

Americamysis bahia (previous name: Mysidopsis bahia)

Details on test organisms:

TEST ORGANISM
- Common name: Mysid shrimp
- Strain: no data
- Source: Aquatic BioSystems; Fort Collins, CO
- Age at study initiation (mean and range, SD): 7 days post hatch
- Length at study initiation (length definition, mean, range and SD): no data
- Weight at study initiation (mean and range, SD): no data
- Method of breeding: no data
- Feeding during test
- Food type: Artemia nauplii during holding time
- Amount: no data
- Frequency: 2 times per day

ACCLIMATION
- Acclimation period: no data
- Acclimation conditions (same as test or not): no data
- Type and amount of food: no data
- Feeding frequency: no data
- Health during acclimation (any mortality observed): no data

QUARANTINE (wild caught)
- Duration: no data
- Health/mortality: no data

Test type:

other: static with solution renewal

Water media type:

saltwater

Limit test:

no

Total exposure duration:

7 d

Post exposure observation period:

No data

Hardness:

No data

Test temperature:

26+-1°C

pH:

No data

Dissolved oxygen:

No data

Salinity:

30+-2 ppt

Nominal and measured concentrations:

- nominal conc.: 0, 0.01, 0.1, 1.0, 10, 100 mg/L
- measured conc.: -, -, -, 0.42, 5.1, - mg/L

Details on test conditions:

TEST SYSTEM
- Test vessel: 250 mL HDPE cup
- Type (delete if not applicable): closed
- Material, size, headspace, fill volume: 200 mL
- Aeration: none
- Type of flow-through (e.g. peristaltic or proportional diluter): no data
- Renewal rate of test solution (frequency/flow rate): Daily solution renewal
- No. of organisms per vessel: 5
- No. of vessels per concentration (replicates): 8
- No. of vessels per control (replicates): 8
- No. of vessels per vehicle control (replicates): 5
- Biomass loading rate: no data

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: 40 Fathoms artificial seawater
- Total organic carbon: no data
- Particulate matter: no data
- Metals: no data
- Pesticides: no data
- Chlorine: no data no data
- Alkalinity: no data
- Ca/mg ratio: no data
- Conductivity: no data
- Culture medium different from test medium: no data
- Intervals of water quality measurement: no data

OTHER TEST CONDITIONS
- Adjustment of pH: no data
- Photoperiod: 16:8
- Light intensity: no data

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :

TEST CONCENTRATIONS
- Spacing factor for test concentrations: 10
- Justification for using less concentrations than requested by guideline: not applicable
- Range finding study
- Test concentrations: 0, 0.01, 0.1, 1, 10, 100 mg/L
- Results used to determine the conditions for the definitive study: no data

Reference substance (positive control):

yes

Remarks:

Copper chloride

Key result

Duration:

48 h

Dose descriptor:

LC50

Effect conc.:

ca. 0.43 mg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

test mat.

Basis for effect:

mortality

Duration:

48 h

Dose descriptor:

LC50

Effect conc.:

ca. 0.43 mg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

test mat.

Basis for effect:

weight

Details on results:

No data

Results with reference substance (positive control):

- Results with reference substance valid
- Mortality: 521 µg/L
- LC50: 434 µg/L (growth)
- Other: none

Reported statistics and error estimates:

No data

Table: Results (means +- standard deviation) of the 7-d toxicity test using M. bahia.

Chlorine dioxide (mg/L)			Survival (%)	Biomass (mg)
Nominal	Measured
0	-		97.5 ± 7.1	0.363 ± 0.053
0.01	-		97.5 ± 7.1	0.354 ± 0.037
0.1	-		97.5 ± 7.1	0.339 ± 0.039
1	0.43		55.0 ± 25.6	0.195 ± 0.066
10	5.1		0	0
100	-		0	0

Validity criteria fulfilled:

not specified

Conclusions:

Toxicity of the substance has been tested on M. bahia, in a 7d acute test. The results demonstrated that a LC50(7d) = 0.43 mg/L.

Executive summary:

Toxicity of the substance has been tested on Mysidopsis bahia, in a 7d acute-renewal test, following US EPA Guideline EPA-821 -R-02-014. A control and five different concentrations (0.01, 0.1, 1, 10, and 100 mg/L) were tested in 8 replicates, each replicate containing 5 individuals. The solution was completely changed every days of the experiment. The results demonstrated a LC50(7d) = 0.43 mg/L of chlorine dioxide.

Description of key information

Daphnia magna were exposed to chlorine dioxide for 48 hours in an acute immobilization test, under GLP and following C.2 EEC Guideline. No animals were immobilized in the control group. EC50(48h) = 0.063 mg/L of 100% ClO2, i.e. 0.032 g/L of 0.2% ClO2 solution being 1 g/L its density.

 

Toxicity of the substance has been tested on Mysidopsis bahia, in a 7d acute-renewal test, following US EPA Guideline EPA-821 -R-02-014.t. The results demonstrated a LC50(7d) = 0.43 mg/L of chlorine dioxide.

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates

Dose descriptor:

EC50

Effect concentration:

0.063 mg/L

Marine water invertebrates

Marine water invertebrates

Dose descriptor:

LC50

Effect concentration:

0.43 mg/L

Additional information

One valid study with Daphnia magna was found on chlorine dioxide. This study was performed under GLP conditions and according to a standard protocol. The results obtained revealed an EC50(48h) = 0.063 mg/L.

Toxicity of the substance in marine water has been tested on Mysidopsis bahia, in a 7d acute-renewal test, following US EPA Guideline EPA-821 -R-02-014. The solution was completely changed every days of the experiment. The results demonstrated a LC50(7d) = 0.43 mg/L of chlorine dioxide.

The short half-life of chlorine dioxide in the environment following use and the fact that there is no direct release of the active substance to aquatic systems, means that no exposure is expected for the aquatic compartment. Chlorine dioxide reacts rapidly in environmental compartments degrading to chlorite and chlorate as dominant species. In the absence of oxidisable substances, and in the presence of pH > 9, chlorine dioxide dissolves in water and decomposes with the slow formation of chlorite and chlorate ions.

Five valid studies on chlorite were found with Daphnia magna, eastern oyster (Crassostrea virginica), and mysid shrimp (Mysidopsis bahia). These studies were performed under GLP and according to standard protocols. Depending on the species, EC50(48h) = 0.064 mg/L (for Daphnia, as chlorine dioxide), 16 mg/L (for eastern oyster), and 0.49 mg/L (for Mysisdopsis bahia); i.e. from 1 to 254 times higher than the EC50 of chlorine dioxide.

Chlorine dioxide and chlorite both degrade rapidly to chlorate under environmental conditions. For this reason, toxicity data on chlorate have been provided.

Two valid studies on chlorate with Daphnia, and mysid shrimp were included. EC50(48h) > 1000 mg/L for both species; i.e. 15873 times higher than the EC50 for chlorine dioxide concentration.

Also, one short-term study valid with restrictions was found for molluscs. From this study (Ward and Boeri, 1991g) it can be seen that marine molluscs are not sensitive to sodium chlorate with an EC­₅₀value based on shell growth and an LC₅₀value both greater than 1000 mg/l sodium chlorate.