Sodium chlorite

Toxicity to aquatic algae and cyanobacteria

Link to relevant study record(s)

Reference

Endpoint:

toxicity to aquatic algae and cyanobacteria

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Remarks:

Analysis of the test solution was performed, but it was not possible to differentiate from the background.

Qualifier:

according to guideline

Guideline:

EPA OPP 122-2 (Algal Toxicity, Tiers I and II)

Deviations:

no

GLP compliance:

yes

Analytical monitoring:

yes

Details on sampling:

Cell counts were made during the 96 h test. Temperature of the incubator was measured and recorded daily, and pH was detected in each test vessel at the beginning and end of the test.

Test organisms (species):

Pseudokirchneriella subcapitata (previous names: Raphidocelis subcapitata, Selenastrum capricornutum)

Test type:

static

Water media type:

freshwater

Total exposure duration:

96 h

Test temperature:

24.5 - 25.3 °C

pH:

7.5 - 7.8

Nominal and measured concentrations:

Nominal concentrations used in the preliminary test:0.1, 1, 10, 100 and 1000 mg sodium chlorite/L(Doses are equivalent to 0.075, 0.75, 7.5, 75 and 750 mg chlorite/L)Nominal concentrations used in the actual test:Nominal concentrations were 0 (control), 0.62, 1.25, 2.5, 5.0 and 10.0 mg/L.(Doses are equivalent to 0, 0.46, 0.93, 1.87, 3.73 and 7.5 mg chlorite/L)

Reference substance (positive control):

no

Duration:

24 h

Dose descriptor:

EC50

Effect conc.:

8 other: mg sodium chlorite/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Duration:

24 h

Dose descriptor:

EC50

Effect conc.:

6 other: mg chlorite/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Duration:

48 h

Dose descriptor:

EC50

Effect conc.:

6.4 other: mg sodium chlorite/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Duration:

48 h

Dose descriptor:

EC50

Effect conc.:

5 other: mg chlorite/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

0.2 other: mg sodium chlorite/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

0.15 other: mg chlorite/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Duration:

96 h

Dose descriptor:

EC50

Effect conc.:

1 other: mg sodium chlorite/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Remarks on result:

other: 95% confidence interval of 0.62 t o1.25 mg/L

Duration:

96 h

Dose descriptor:

EC50

Effect conc.:

0.75 other: mg chlorite/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Details on results:

Results of the preliminary test:After 96 h the number of cells / mL was less than 50 % of the control value at 10, 00 and 1000 mg/L sodium chlorite and greater than 50 % at all other concentrations.Results of the actual test:Exposure of the algae to sodium chlorite for 96 h resulted in a median effective concentration (EC50) of 1.0 mg/L with a 95% confidence interval of 0.62 to 1.25 mg/L (equivalent to 6 mg chlorite/L). No effects were noted.

Table A7_4_1_3(2)-5:        Cell concentration data

		Number of cells/ml x 10^3
Nominal Concentration (mg sodium chlorite/L)	Replicate	0 h	24 h	48 h	72 h	96 h
0 (control)	1	10	42	100	346	1404
	2	10	54	108	428	1744
	3	10	46	132	446	1664
	mean	10	47	113	407	1604
	% control	100	100	100	100	100
0.62	1	10	44	104	358	1484
	2	10	56	132	436	1852
	3	10	40	110	412	1316
	mean	10	47	115	402	1551
	% control	100	100	102	99	97
1.25	1	10	42	92	156	274
	2	10	36	96	236	631
	3	10	34	110	190	576
	mean	10	37	99	194	494
	% control	100	79	88	48	31
2.5	1	10	40	108	228	364
	2	10	32	112	182	326
	3	10	34	92	176	296
	mean	10	35	104	195	329
	% control	100	74	92	48	20
5.0	1	10	44	90	108	138
	2	10	22	80	122	212
	3	10	32	54	60	116
	mean	10	33	75	97	155
	% control	100	70	66	24	10
10.0	1	10	16	30	12	16
	2	10	24	26	24	14
	3	10	18	16	18	12
	mean	10	19	24	18	14
	% control	100	40	21	4	1

Validity criteria fulfilled:

yes

Remarks:

(according to EU method C.3 the quality criteria are met: The cell density in the control cultures have increased by a factor of at least 16).

Conclusions:

Exposure of algae to sodium chlorite for 96 h resulted in a median EC50 of 1.0 mg/L, with a 95% confidence interval of 0.62 to 1.25 mg/L (equivalent to 0.75 mg chlorite/L)

Executive summary:

The aim of the study was to investigate the toxicity to aquatic algae due to the test material.

The test procedure used was EPA OPP 122-2 (Algal Toxicity, Tiers I and II).

Nominal concentrations used in the preliminary test: 0.1, 1, 10, 100 and 1000 mg sodium chlorite/L (Doses are equivalent to 0.075, 0.75, 7.5, 75 and 750 mg chlorite/L).

The result was as follows:

Exposure of algae to sodium chlorite for 96 h resulted in a median EC50 of 1.0 mg/L, with a 95% confidence interval of 0.62 to 1.25 mg/L (equivalent to 0.75 mg chlorite/L)

Description of key information

Key study. The test procedure used was EPA OPP 122-2 (Algal Toxicity, Tiers I and II). The result was as follows: Exposure of algae to sodium chlorite for 96 h resulted in a median EC50 of 1.0 mg/L, with a 95% confidence interval of 0.62 to 1.25 mg/L (equivalent to 0.75 mg chlorite/L

Key value for chemical safety assessment

EC50 for freshwater algae:

1 mg/L

Additional information

Key study. The test procedure used was EPA OPP 122-2 (Algal Toxicity, Tiers I and II). The result was as follows: Exposure of algae to sodium chlorite for 96 h resulted in a median EC50 of 1.0 mg/L, with a 95% confidence interval of 0.62 to 1.25 mg/L (equivalent to 0.75 mg chlorite/L)