Sodium dichromate

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:

other: See 'Remarks'

Remarks:

Guideline study, however without detailed documentation (information on test conditions missing, including pH, dissolved oxygen, temperature, age of test organisms at test initiation).

Reason / purpose for cross-reference:

reference to same study

Qualifier:

according to guideline

Guideline:

other: US EPA 600/4-85/013

Version / remarks:

1985

Qualifier:

according to guideline

Guideline:

other: US EPA 600/4-78/012

Version / remarks:

1978

Principles of method if other than guideline:

Within a testing program to determine the use of hexavalent chromium as a reference toxicant, a 48 h acute toxicity test was conducted with Ceriodaphnia sp. in soft water with the test substance potassium dichromate (K2Cr2O7).

GLP compliance:

not specified

Remarks:

not specified in publication

Analytical monitoring:

yes

Details on sampling:

- Concentrations: Samples were taken from all nominal test concentrations for analysis of total Cr. Samples were taken from the low, middle and high concentrations for analysis of Cr(VI).
- Sampling method: Samples were taken at the toxicity testing laboratories and sent to an independent analytical laboratory for determination of total Cr and Cr(VI)
- Sample storage conditions before analysis: refrigerated

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Method: Stock solutions were prepared in freshwater and diluted to the target nominal concentrations .

Test organisms (species):

Ceriodaphnia sp.

Details on test organisms:

TEST ORGANISM
- Age at study initiation: not specified
- Feeding during test : not specified

ACCLIMATION
- Acclimation period: not specified
- Acclimation conditions: culturing conditions same as test conditions
- Type and amount of food: 0.1 ml algae and yeast suspensions (laboratory II)
- Feeding frequency: daily

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

48 h

Hardness:

40-48 mg/L as CaCO3 (lab II)

Nominal and measured concentrations:

Nominal: Control, 0.06, 0.10, 0.18, 0.32, 0.56 mg Cr/L (lab II)
Measured: see table 2 in 'Any other information on results incl. tables'

Details on test conditions:

TEST SYSTEM
- No. of organisms per vessel: 10
- No. of vessels per concentration (replicates): 5
- No. of vessels per control (replicates): 5

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: soft water (lab II)

Reference substance (positive control):

no

Key result

Duration:

48 h

Dose descriptor:

EC50

Effect conc.:

0.03 mg/L

Nominal / measured:

meas. (not specified)

Conc. based on:

element

Remarks:

Cr

Basis for effect:

mobility

Details on results:

- Mortality of control: Control survival 100%
- Concentrations of Cr persisted throughout tests with little conversion of Cr(VI) to Cr(III))

Reported statistics and error estimates:

EC50 and LC50 values were calculated on the basis of measured and nominal concentrations; they were not corrected for control mortality and were reported with preference first for probit, second for moving angle average and third for linear interpolation analyses. 95% confidence intervals were also given.

Table 2: Results of analyses of total chromium and hexavalent chromium (laboratoy II) for tests with Daphnia pulex

		Cr(VI) [mg/L]		total Cr [mg/L]
Sample	Nominal	t = 0 h	t= 48 h	t = 0 h	t= 48 h
Test 1
A	0.56	not sampled	0.61	not sampled	0.70
B	-	-	-	-	-
C	0.32	not sampled	0.35	not sampled	0.40
D	-	-	-	-	-
E	0.10	not sampled	0.12	not sampled	0.12
A	0.56	0.58	0.61	0.64	0.64
C	0.18	0.20	0.18	0.22	0.22
D	0.10	-	-	0.12	0.13
E	0.06	0.06	0.07	0.08	0.06
A	0.56	0.63	0.66	0.67	0.67
B	0.32	-	-	0.40	0.40
C	0.18	0.20	0.20	0.22	0.20
D	0.10	-	-	0.10	0.10
E	0.06	0.07	0.07	0.08	0.05

Measured concentrations for the test with Ceriodaphnia sp. are not reported in detail.

Validity criteria fulfilled:

yes

Remarks:

Control survival 100%; dissolved oxygen concentrations not reported

Conclusions:

Within a testing program to determine the use of hexavalent chromium as a reference toxicant, a 48 h acute toxicity test was conducted with Ceriodaphnia sp. in soft water with the test substance potassium dichromate (K2Cr2O7) according to test guidelines US EPA/600/4-85/013 and US EPA/600/4-78/012. The derived 48 h EC50 amounted to 0.03 mg Cr/L (measured) for the mobility of Ceriodaphnia sp..

Reference 2

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:

other: See 'Remarks'

Remarks:

Guideline study, however without detailed documentation (information on test conditions missing, including pH, dissolved oxygen, temperature, age of test organisms at test initiation). From a total of 9 tests conducted in 2 laboratories, only 3 can be considered valid based on control mortality ≤10 %.

Reason / purpose for cross-reference:

reference to same study

Qualifier:

according to guideline

Guideline:

other: US EPA 600/4-85/013

Version / remarks:

1985

Qualifier:

according to guideline

Guideline:

other: US EPA 600/4-78/012

Version / remarks:

1978

Principles of method if other than guideline:

Within a testing program to determine the use of hexavalent chromium as a reference toxicant, several 48 h acute toxicity tests were conducted with Daphnia pulex in two different laboratories (referenced as lab I and lab II) with the test substance potassium dichromate (K2Cr2O7).

GLP compliance:

not specified

Remarks:

not specified in publication

Analytical monitoring:

yes

Details on sampling:

- Concentrations: Samples were taken from all nominal test concentrations for analysis of total Cr. Samples were taken from the low, middle and high concentrations for analysis of Cr(VI).
- Sampling method: Samples were taken at the toxicity testing laboratories and sent to an independent analytical laboratory for determination oc total Cr and Cr(VI)
- Sample storage conditions before analysis: refrigerated

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Method: Stock solutions were prepared in freshwater and diluted to the target nominal concentrations .

Test organisms (species):

Daphnia pulex

Details on test organisms:

TEST ORGANISM
- Age at study initiation: not specified
- Feeding during test : not specified

ACCLIMATION
- Acclimation period: not specified
- Acclimation conditions: culturing conditions same as test conditions
- Type and amount of food: 10 ml of concentrated Selanastrum capricornutum culture (laboratory I); 0.1 ml algae and yeast suspensions (laboratory II)
- Feeding frequency: daily

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

48 h

Hardness:

72-80 mg/L as CaCO3 (lab I)
40-48 mg/L as CaCO3 (lab II)

Nominal and measured concentrations:

Nominal: Control, 0.1, 0.15, 0.20, 0.25, 0.30 mg Cr/L (lab I); 0.06, 0.10, 0.18, 0.32, 0.56 mg Cr/L (lab II)
Measured: see table 2 and 3 in 'Any other information on results incl. tables'

Details on test conditions:

TEST SYSTEM
- No. of organisms per vessel: 10
- No. of vessels per concentration (replicates): 5
- No. of vessels per control (replicates): 5

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: moderately hard, reconstituted water (lab I); soft water (lab II)

Reference substance (positive control):

no

Key result

Duration:

48 h

Dose descriptor:

EC50

Effect conc.:

0.077 mg/L

Nominal / measured:

meas. (not specified)

Conc. based on:

element

Remarks:

Cr

Basis for effect:

mobility

Remarks on result:

other: mean value of 3 tests with valid control results

Duration:

48 h

Dose descriptor:

EC50

Effect conc.:

0.083 mg/L

Nominal / measured:

nominal

Conc. based on:

element

Remarks:

Cr

Basis for effect:

mobility

Remarks on result:

other: mean value of 3 tests with valid control results

Details on results:

- Mortality of control: Control mortality ≤10% in 3 of 9 tests; survival between 80 and 89 % in 6 of 9 tests
- EC50 was based on values of tests with valid control results (control mortality ≤10%)
- Concentrations of Cr persisted throughout tests with little conversion of Cr(VI) to Cr(III))

Reported statistics and error estimates:

EC50 and LC50 values were calculated on the basis of measured and nominal concentrations; they were not corrected for control mortality and were reported with preference first for probit, second for moving angle average and third for linear interpolation analyses. 95% confidence intervals were also given.

Table 2: Results of analyses of total chromium and hexavalent chromium (laboratoy I)

		Cr(VI) [mg/L]		total Cr [mg/L]
Sample	Nominal	t = 0 h	t= 48 h	t = 0 h	t= 48 h
Test 1
A	0.1	0.28	0.28	0.30	0.30
B	0.15	-	-	0.10	0.20
C	0.20	0.13	0.12	0.15	0.12
D	0.25	-	-	0.15	0.15
E	0.30	0.09	0.09	0.10	0.10
Test 2
A	0.1	0.10	0.14	0.10	0.10
C	0.20	0.9	0.19	0.20	0.20
D	0.25	-	-	0.20	0.20
E	0.30	0.30	0.33	0.30	0.30
Test 3
A	0.1	0.12	0.01	0.10	<0.02
B	0.15	-	-	0.16	<0.02
C	0.20	0.22	0.02	0.20	0.02
D	0.25	-	-	0.25	0.05
E	0.30	0.30	0.02	0.30	0.04

Table 3: Results of analyses of total chromium and hexavalent chromium (laboratoy II)

		Cr(VI) [mg/L]		total Cr [mg/L]
Sample	Nominal	t = 0 h	t= 48 h	t = 0 h	t= 48 h
Test 1
A	0.56	not sampled	0.61	not sampled	0.70
B	-	-	-	-	-
C	0.32	not sampled	0.35	not sampled	0.40
D	-	-	-	-	-
E	0.10	not sampled	0.12	not sampled	0.12
A	0.56	0.58	0.61	0.64	0.64
C	0.18	0.20	0.18	0.22	0.22
D	0.10	-	-	0.12	0.13
E	0.06	0.06	0.07	0.08	0.06
A	0.56	0.63	0.66	0.67	0.67
B	0.32	-	-	0.40	0.40
C	0.18	0.20	0.20	0.22	0.20
D	0.10	-	-	0.10	0.10
E	0.06	0.07	0.07	0.08	0.05

Validity criteria fulfilled:

yes

Remarks:

Control mortality ≤10% in 3 of 9 tests; dissolved oxygen concentrations not reported

Conclusions:

Within a testing program to determine the use of hexavalent chromium as a reference toxicant, a total of 9 acute toxicity tests (48 h) were conducted with Daphnia pulex in two different laboratories with the test substance potassium dichromate (K2Cr2O7) according to test guidelines US EPA/600/4-85/013 and US EPA/600/4-78/012. Three of these tests fulfilled the validity criterion of control mortality ≤10% (OECD 202) and were thus used to derive the mean EC50 value based on measured chromium concentrations. The derived mean 48 h EC50 amounted to 0.077 mg Cr/L (measured) for the mobility of Daphnia pulex.

Reference 3

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:

other: See 'Remarks'

Remarks:

Guideline study, however without detailed documentation (information on test conditions missing, including pH, dissolved oxygen, temperature). From a total of 9 tests conducted in 2 laboratories, only 6 can be considered valid based on control mortality ≤10 %.

Qualifier:

according to guideline

Guideline:

other: US EPA 600/4-85/013

Version / remarks:

1985

Qualifier:

according to guideline

Guideline:

other: US EPA 600/4-78/012

Version / remarks:

1978

Principles of method if other than guideline:

Within a testing program to determine the use of hexavalent chromium as a reference toxicant, a 48 h acute toxicity test was conducted with Mysidopsis bahia and Mysidopsis almyra in artificial seawater with the test substance potassium dichromate (K2Cr2O7).

GLP compliance:

not specified

Remarks:

not specified in publication

Analytical monitoring:

yes

Details on sampling:

- Concentrations: Samples were taken from all nominal test concentrations for analysis of total Cr. Samples were taken from the low, middle and high concentrations for analysis of Cr(VI).
- Sampling method: Samples were taken at the toxicity testing laboratories and sent to an independent analytical laboratory for determination of total Cr and Cr(VI)
- Sample storage conditions before analysis: refrigerated

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Method: Stock solutions were prepared in seawater and diluted to the target nominal concentrations.

Test organisms (species):

other: Mysidopsis bahia & Mysidopsis almyra

Details on test organisms:

TEST ORGANISM
- Age at study initiation: 48 h (laboratory I); 48-120 h (laboratory II)
- Feeding during test: not specified

ACCLIMATION
- Acclimation period: 24 h
- Acclimation conditions: same as test conditions
- Type and amount of food: 48 h old Artemia nauplii daily

Test type:

static

Water media type:

saltwater

Limit test:

no

Total exposure duration:

48 h

Hardness:

Not reported.

Test temperature:

Not reported.

pH:

Not reported.

Dissolved oxygen:

Not reported.

Salinity:

20 ‰

Nominal and measured concentrations:

Nominal: Control, 1, 2, 5, 10, 15, 20 mg Cr/L (lab I); Control, 1.8, 3.2, 5.6, 7.5, 10 mg Cr/L (lab II)
Measured: see table 2 and 3 in 'Any other information on results incl. tables'

Details on test conditions:

TEST SYSTEM
- No. of organisms per vessel: 10
- No. of vessels per concentration (replicates): 5
- No. of vessels per control (replicates): 5

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: artificial seawater

OTHER TEST CONDITIONS
- Photoperiod: 18:6 h light:dark (lab 1), 14:10 h light:dark (lab II)

Reference substance (positive control):

no

Duration:

48 h

Dose descriptor:

LC50

Effect conc.:

5.13 mg/L

Nominal / measured:

meas. (not specified)

Conc. based on:

element

Remarks:

Cr(VI)

Basis for effect:

mortality

Remarks on result:

other: Mysidopsis almyra

Duration:

48 h

Dose descriptor:

LC50

Effect conc.:

6.49 mg/L

Nominal / measured:

meas. (not specified)

Conc. based on:

element

Remarks:

Cr(VI)

Basis for effect:

mortality

Remarks on result:

other: Mysidopsis bahia

Remarks:

mean value of 5 tests with valid control results

Duration:

48 h

Dose descriptor:

LC50

Effect conc.:

7.07 mg/L

Nominal / measured:

nominal

Conc. based on:

element

Remarks:

Cr(VI)

Basis for effect:

mortality

Remarks on result:

other: Mysidoposis bahia

Remarks:

mean value of 5 tests with valid control results

Details on results:

- Mortality of control: Control mortality ≤10% in 6 of 9 tests; survival between 82 and 86 % in 3 of 9 tests
- LC50 values were based on values of tests with valid control results (control mortality ≤10%)
- Concentrations of Cr persisted throughout tests with little conversion of Cr(VI) to Cr(III)

Reported statistics and error estimates:

EC50 and LC50 values were calculated on the basis of measured and nominal concentrations; they were not corrected for control mortality and were reported with preference first for probit, second for moving angle average and third for linear interpolation analyses. 95% confidence intervals were also given.

Table 2: Results of analyses of total chromium and hexavalent chromium (laboratoy I)

		Cr(VI) [mg/L]		total Cr [mg/L]
Sample	Nominal	t = 0 h	t= 48 h	t = 0 h	t= 48 h	measured by lab I
Test 1
A	1	<0.01	0.85	<0.1	0.88	0.39
B	2	-	-	1.0	1.7	1.23
C	5	1.8	4.7	1.8	4.8	3.40
D	10	-	-	4.8	10	8.83
E	15	13	10	14	14	12.9
Test 2
A	1	1.2	2.2	0.1	1.9	0.34
B	2	-	-	2.0	2.0	1.15
C	5	5.9	5.6	5.8	5.6	3.15
D	10	-	-	11	8.4	10.7
E	20	19	8.9	20	18	18.8
Test 3
A	1	0.86	0.26	0.88	0.4	0.32
B	2	-	-	1.7	1.7	0.83
C	5	4.9	4.3	4.8	4.8	2.50
D	10	-	-	10	10	10.6
E	20	10	5.1	19	9.5	18.1

Table 3: Results of analyses of total chromium and hexavalent chromium (laboratoy II)

		Cr(VI) [mg/L]		total Cr [mg/L]
Sample	Nominal	t = 0 h	t= 48 h	t = 0 h	t= 48 h
Test 1
A	10	9.5	10	10	10
B	7.5	-	-	8	7.1
C	5.6	5.4	5.5	5.6	5.6
D	3.2	-	-	3.3	3.1
E	1.8	1.8	1.7	1.8	1.8
A	10	9.7	10	9.5	10
B	7.5	-	-	7.2	7.5
C	5.6	5.4	5.6	5.2	5.8
D	3.2	-	-	3.2	3.2
E	1.8	1.7	1.9	1.6	1.8
A	10	9.7	10	10	10
B	7.5	-	-	7.5	8.0
C	5.6	5.3	5.6	5.8	5.7
D	3.2	-	-	3.2	not sampled
E	1.8	1.7	3.4	1.8	3.4

Validity criteria fulfilled:

yes

Remarks:

Control mortality ≤10% in 6 of 9 tests

Conclusions:

Within a testing program to determine the use of hexavalent chromium as a reference toxicant, a total of 9 acute toxicity tests (48 h) were conducted with Mysidopsis bahia (8 tests) and Mysidopsis almyra (1 test) in two different laboratories with the test substance potassium dichromate (K2Cr2O7) in artificial seawater (salinity 20 ‰) according to test guidelines US EPA/600/4-85/013 and US EPA/600/4-78/012. Six of these tests fulfilled the validity criterion of control mortality ≤10% (EPA OPPTS 850.1035 (Mysid acute toxicity test)) and were thus used to derive the mean LC50 value based on measured chromium concentrations. The derived 48 h LC50 amounted to 6.49 mg Cr(VI)/L (measured) for the mortality of Mysidopsis bahia (mean of 5 tests) and 5.13 mg Cr(VI)/L for the mortality of Mysidopsis almyra.

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:

other: See 'Remarks'

Remarks:

Guideline study without detailed documentation. No information on validity provided (control immobilisation, dissolved oxygen concentrations during test). Nominal test concentrations are not specified in detail and measured concentrations are not reported. Furthermore, age of test organisms at test initiation are not reported.

Qualifier:

according to guideline

Guideline:

other: US EPA/600/4-85/013: Methods for measuring the acute toxicity of effluents to freshwater and marine organisms

Version / remarks:

3rd edition, 1985

Principles of method if other than guideline:

A 48 h acute toxicity test was conducted with Daphnia pulex in moderately hard water with the test substances potassium dichromate (K2Cr2O7) and potassium chromate (K2CrO4).

GLP compliance:

not specified

Remarks:

not specified in publication

Analytical monitoring:

yes

Details on sampling:

- Initial total chromium concentrations were determined in all test chambers. Hexavalent chromium concentrations were determined for a series of six samples in each test.

Vehicle:

no

Details on test solutions:

Stock hexavalent chromium solutions were prepared from potassium dichromate and potassium chromate.

Test organisms (species):

Daphnia pulex

Details on test organisms:

TEST ORGANISM
- Common name: Daphnia pulex
- Source: laboratory culture

FEEDING DURING TEST
- no feeding

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

48 h

Hardness:

75-105 mg CaCO2/L

Test temperature:

20 ± 2 °C

pH:

7.5-7.9

Dissolved oxygen:

7.0-9.0 mg/L

Salinity:

-

Conductivity:

280-400 µS

Nominal and measured concentrations:

Test concentrations not specified in detail, range: 0.05-10 mg/L

Details on test conditions:

TEST SYSTEM
- Test vessel: 250-ml beakers
- Fill volume: 200 ml
- No. of organisms per vessel: 10
- No. of vessels per concentration (replicates): 5
- No. of vessels per control (replicates): 5
- Biomass loading rate: 20 mL per daphnid

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: Moderately hard water
- Alkalinity: 50-60 mg CaCO3/L

OTHER TEST CONDITIONS
- Photoperiod: 16:8 h light:dark

EFFECT PARAMETERS MEASURED:
- immobility (at 48 h)

TEST CONCENTRATIONS
- Spacing factor for test concentrations: test concentrations not specified in detail, range: 0.05-10 mg/L

Reference substance (positive control):

no

Duration:

48 h

Dose descriptor:

EC50

Effect conc.:

0.18 mg/L

Nominal / measured:

meas. (not specified)

Conc. based on:

element

Remarks:

Cr(VI)

Basis for effect:

mobility

Remarks on result:

other: mean of two tests; 95% CI: 0.13-0.19 mg/L

Details on results:

- Mortality of control: not reported
- Mean measured concentrations of total chromium during the acute toxicity tests with both salts were generally within 95% of the nominal concentrations, and remained constant at each exposure during the tests
- Selected analyses for hexavalent chromium confirmed that all of the chromium was in the hexavalent state.

Reported statistics and error estimates:

Acute LC50 values and 95% confidence limits were calculated by the moving average angle method.

In a similar test carried out with potassium chromate (K2CrO4), a 48 h EC50 of 0.18 mg Cr(VI)/L (measured, initial) was determined for Daphnia pulex.

Validity criteria fulfilled:

not specified

Remarks:

no information on control immobilisation and dissolved oxygen concentrations during test is provided

Conclusions:

A 48 h static acute toxicity test was conducted with Daphnia pulex in moderately hard water with the test substances potassium dichromate (K2Cr2O7) and potassium chromate (K2CrO4) according to test guideline US EPA/600/4-85/013. The derived 48 h EC50 amounts to 0.18 mg Cr(VI)/L (measured) for potassium dichromate as well potassium chromate.

Reference 5

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:

other: See 'Remarks'

Remarks:

Guideline study without detailed documentation. No information on validity provided (control immobilisation/mortality). Nominal test concentrations are not specified in detail and measured concentrations are not reported. The age of test organisms at test initiation are not reported.

Qualifier:

according to guideline

Guideline:

other: US EPA/600/4-85/013: Methods for measuring the acute toxicity of effluents to freshwater and marine organisms

Version / remarks:

3rd edition, 1985

Principles of method if other than guideline:

A 48 h acute toxicity test was conducted with mysid shrimp Mysidopsis bahia in reconstituted sea water with the test substances potassium dichromate (K2Cr2O7) and potassium chromate (K2CrO4).

GLP compliance:

not specified

Remarks:

not specified in publication

Analytical monitoring:

yes

Details on sampling:

- Initial total chromium concentrations were determined in all test chambers. Hexavalent chromium concentrations were determined for a series of six samples in each test.

Vehicle:

no

Details on test solutions:

Stock hexavalent chromium solutions were prepared from potassium dichromate and potassium chromate.

Test organisms (species):

Americamysis bahia (previous name: Mysidopsis bahia)

Details on test organisms:

TEST ORGANISM
- Common name: Mysidopsis bahia
- Source: commercial supplier

ACCLIMATION
- Acclimation period: minimum 24 hours
- Acclimation conditions: same as test

FEEDING DURING TEST
- Artemia at 0 and 24 h

Test type:

static

Water media type:

saltwater

Limit test:

no

Total exposure duration:

48 h

Hardness:

3500-4200 mg CaCO2/L

Test temperature:

20 ± 2 °C

pH:

8.0-8.4

Dissolved oxygen:

7.0-9.0 mg/L

Salinity:

20 ‰

Conductivity:

27000-29000 µS

Nominal and measured concentrations:

Test concentrations not specified in detail, range: 0.05-10 mg/L

Details on test conditions:

TEST SYSTEM
- Test vessel: 4-L glass jars
- Fill volume: 2 L
- No. of organisms per vessel: 10
- No. of vessels per concentration (replicates): 5
- No. of vessels per control (replicates): 5
- Biomass loading rate: 100 mL per mysid

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: Reconstituted sea water
- Alkalinity: 300-400 mg CaCO3/L

OTHER TEST CONDITIONS
- Photoperiod: 16:8 h light:dark

EFFECT PARAMETERS MEASURED:
- immobility (at 48 h)

TEST CONCENTRATIONS
- Spacing factor for test concentrations: test concentrations not specified in detail, range: 0.05-10 mg/L

Reference substance (positive control):

no

Duration:

48 h

Dose descriptor:

EC50

Effect conc.:

6.3 mg/L

Nominal / measured:

meas. (not specified)

Conc. based on:

element

Remarks:

Cr(VI)

Basis for effect:

other:

Remarks:

immobility

Remarks on result:

other: mean of two tests; 95% CI: 5.6-7.1 mg/L

Details on results:

- Mortality of control: not reported
- Mean measured concentrations of total chromium during the acute toxicity tests with both salts were generally within 95% of the nominal concentrations, and remained constant at each exposure during the tests
- Selected analyses for hexavalent chromium confirmed that all of the chromium was in the hexavalent state.

In a similar test carried out with potassium chromate (K2CrO4), a 48 h EC50 of 6.0 mg Cr(VI)/L (measured, initial) was determined for Mysidopsis bahia.

Validity criteria fulfilled:

not specified

Remarks:

no information on control immobilisation/mortality is provided

Conclusions:

A 48 h static acute toxicity test was conducted with Mysidopsis bahia in reconstituted seawater with the test substances potassium dichromate (K2Cr2O7) and potassium chromate (K2CrO4) according to test guideline US EPA/600/4-85/013. The derived 48 h EC50 amounts to 6.3 mg Cr(VI)/L (measured) for potassium dichromate and to 6.0 mg Cr(VI)/L (measured) for potassium chromate, respectively.

Description of key information

Reliable data on the short-term toxicity of soluble chromium (VI) substances to freshwater invertebrates are available from two reliable studies covering two freshwater species (Ceriodaphnia sp., Daphnia pulex). The lowest acute EC50 for freshwater invertebrates, 0.03 mg Cr/L, was observed for the effect of potassium dichromate in a 48 h toxicity test with Ceriodaphnia sp.

Reliable data on the short-term toxicity of soluble chromium (VI) substances to saltwater invertebrates are available from two reliable studies covering two marine species (Mysidopsis bahia, Mysidopsis almyra). The lowest acute LC50 for saltwater invertebrates, 5.13 mg Cr/L, was observed for the effect of potassium dichromate in a 48 h toxicity test with Mysidopsis almyra in artificial seawater.

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates

Effect concentration:

0.03 mg/L

Marine water invertebrates

Marine water invertebrates

Effect concentration:

5.13 mg/L

Additional information

Freshwater

Two reliable short-term toxicity studies covering two freshwater invertebrate species (Daphnia pulex, Ceriodaphnia sp.) are available for (soluble) chromium (VI) substances. Tests were performed with potassium chromate (K2CrO4) and/or potassium dichromate (K2Cr2O7).

Within a testing program to determine the use of hexavalent chromium as a reference toxicant, a total of 9 acute toxicity tests (48 h) were conducted with Daphnia pulex and one test with Ceriodaphnia sp. with the test substance potassium dichromate (Dorn et al. 1987). Three of the tests with D. pulex fulfilled the validity criterion of control mortality ≤10% (OECD 202) and were thus used to derive the mean EC50 value based on measured chromium concentrations. The derived mean 48 h EC50 amounted to 0.077 mg Cr/L (measured) for the mobility of Daphnia pulex. For Ceriodaphnia sp. the derived 48 h EC50 amounts to 0.03 mg Cr/L (measured, mobility).

Furthermore, a 48 h static acute toxicity test was conducted with Daphnia pulex in moderately hard water with potassium dichromate (K2Cr2O7) and potassium chromate (K2CrO4) by Jop et al. (1987). The derived 48 h EC50 amounts to 0.18 mg Cr(VI)/L (measured) for potassium dichromate and potassium chromate.

In addition, acute toxicity data for freshwater invertebrates Daphnia magna, Daphnia pulex and Ceriodaphnia reticulata are available from 2 unreliable studies (Klimisch 3).

In an unreliable 48-h static acute toxicity test on the effect of sodium dichromate on 3 daphnid species, the lowest 48h EC50 of 0.11 mg Cr(VI)/L (nominal) was determined for the immobilisation/mortality of Daphnia magna whereas 48 h EC50 values of 0.12 and 0.20 mg Cr(VI)/L (nominal) were derived for Daphnia pulex and Ceriodaphnia reticulata, respectively (Elnabarawy et al. 1986; Klimisch 3).

Sodium chromate was tested for its toxicity to the aquatic invertebrate Daphnia magna in a study with methodological shortcomings. Juvenile (12 ± 12 h old) and adult Daphnia (> 7 days old) were exposed to concentrations between 10 and 1000 µg/L for 96 h. A difference in toxicity due to organism's age was not observed. A 96 h LC50 of 0.05 mg Cr/L (nominal, mortality) was determined (Trabalka & Gehrs 1977; Klimisch 3).

Saltwater

Reliable data on the short-term toxicity of soluble chromium (VI) substances to saltwater invertebrates are available from two reliable studies covering two marine species (Mysidopsis bahia, Mysidopsis almyra). Tests were performed with potassium chromate (K2CrO4) and/or potassium dichromate (K2Cr2O7).

Within a testing program to determine the use of potassium dichromate as reference toxicant, a total of 9 acute toxicity tests (48 h) were conducted with Mysidopsis bahia (8 tests) and Mysidopsis almyra (1 test) in artificial seawater (salinity 20 ‰) (Dorn et al. 1987). Six of these tests fulfilled the validity criterion of control mortality ≤10% and were thus used to derive the mean LC50 value based on measured chromium concentrations. The derived 48 h LC50 amounts to 6.49 mg Cr(VI)/L (measured) for the mortality of Mysidopsis bahia (mean of 5 tests) and 5.13 mg Cr(VI)/L for the mortality of Mysidopsis almyra.

Further, a 48 h static acute toxicity test was conducted with Mysidopsis bahia in reconstituted seawater with potassium dichromate and potassium chromate (Jop et al. 1987). The derived 48 h EC50 values amount to 6.3 mg Cr(VI)/L (measured) for potassium dichromate and to 6.0 mg Cr(VI)/L (measured) for potassium chromate, respectively.

In addition, acute toxicity data for marine invertebrate Neanthes arenaceodentata are available from one unreliable study (Oshida et al. 1981; Klimisch 3): 7-d toxicity tests with potassium dichromate were conducted on two Neanthes arenaceodentata populations (laboratory culture and 'wild' type) in seawater, and 7 d LC50 values amount to 1.44-1.89 mg Cr/L and 1.48 mg Cr/L (nominal) for laboratory and 'wild' cultures, respectively. Furthermore, the 96 h LC50 for laboratory cultures ranged from 2.2 to 4.3 mg Cr/L (nominal).