Chromium trioxide

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:

supporting study

Study period:

From 1973 to 1989

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: see 'Remark'

Remarks:

The EU RAR summarises the results of a number of acute invertebrate toxicity studies which, individually, have limitations regarding study design and reliability. However, the results of these studies when taken as a whole, provide an adequate estimate of the acute toxicity to aquatic invertebrates. The data are considered to fulfil the criteria laid down in Annex XI to Regulation 1907/2006: adequate for classification and labelling, adequate coverage of key parameters (lethality), exposure duration comparable or longer that Article 13(3) methods ( 48 hours), adequate documentation provided: EU RAR, of which parts have been copied to this endpoint record. Reliability for endpoint also increased based on test results from several species.

Qualifier:

no guideline followed

Guideline:

other: range of studies included

Principles of method if other than guideline:

Several studies, collectively, provide a weight-of-evidence to support the acute toxicity

GLP compliance:

no

Analytical monitoring:

yes

Details on sampling:

Various sampling procedures based on multiple studies

Details on test solutions:

Various test media prepared based on multiple studies in freshwater and salt water

Test organisms (species):

other: Range of species tested

Test type:

other: Range of test designs used

Water media type:

not specified

Post exposure observation period:

None reported

Hardness:

Range used from multiple studies

Test temperature:

Range used from multiple studies

pH:

Range used from multiple studies

Dissolved oxygen:

Range used from multiple studies

Salinity:

Range used from multiple studies

Nominal and measured concentrations:

Range used from multiple studies

Details on test conditions:

Range used from multiple studies

Reference substance (positive control):

no

Details on results:

PPotassium dichromate is recommended as a reference substance in the acute toxicity to Daphnia test (Method C.2; EEC, 1992). A ring test involving 129 EC50 determinations from 46 laboratories determined the mean 24h-EC50 value as 1.5 mg K2Cr2O7/l (EEC, 1992). This is
equivalent to an EC50 of 0.53 mg Cr/l, expressed on a concentration of chromium basis. The toxicity of chromium (VI) to invertebrates in short-term tests appears to depend on water properties such as hardness, pH and temperature. Persoone et al. (1989) noted decreasing EC50
values for Daphnia magna with decreasing hardness and with increasing temperature. Although the conditions included some which were outside those recommended, checks were carried out to make sure that they did not cause mortality or stress in the controls. Longer term tests appear
to show less influence of the properties on toxicity, but there are few if any studies where the properties have been varied. It may be noted that there are no long-term studies in low hardness waters (<50 mg CaCO3/l). For some invertebrates, toxicity data is available for more than one of the chromium (VI) compounds included in this assessment. The limited available information indicates that, when expressed on a total chromium concentration, there are no significant differences between the toxicity of sodium chromate, sodium dichromate and potassium dichromate (allowing for
differences in water properties). This is as would be expected if the equilibria between the chromate and dichromate anions are established in the test medium. Little information is available for ammonium dichromate and chromic acid, but it would be expected that their toxicity would be similar to that of the other chromates/dichromates, when expressed on a total chromium concentration basis.

The results of the acute aquatic invertebrate toxicity studies evaluated in the EU RAR are summarised below:

Species	Endpoint		Value (mg/L)		Reference
Freshwater
Crustaceans
Ceriodaphnia sp		48 h LC50		0.03	Dorn et al. (1987)
Ceriodaphnia dubia		24 h LC50		0.053	Hickey (1989)
Ceriodaphnia pulchella		24 h LC50		0.196	Hickey (1989)
Ceriodaphnia reticulata		48 h EC50		0.195a	Elnabarawy et al. (1986)
Crangonyx pseudogracilis		96 h LC50		0.42	Martin and Holdrich (1986)
Daphnia carinata		24 h EC50		0.423	Hickey (1989)
Daphnia magna		48 h EC50		0.035 0.112a 0.05b	Stephenson and Watts (1984) Elnabarawy et al. (1986) Trabalka and Gehrs (1977)
Daphnia obtuse		48 h EC50		0.061	Coniglio and Baudo (1989)
Daphnia pulex		48 h EC50		0.063 0.122a 0.18c	Dorn et al. (1987) Elnabarawy et al. (1986) Jop et al. (1987)
Macrobrachium lamarrei		96 h LC50		0.65	Murti et al. (1983)
Simocephalus vetulas		24 h EC50		0.154	Hickey (1989)
Insects
Chironomus tentans		48 h LC50		11.8	Khangarot and Ray (1989a)
Molluscs
Biomphalaria glabrata		96 h LC50		37.3	Bellavere and Gorbi (1981)
Goniobasis levescens		48 h LC50		2.4	Cairns Jr. et al. (1976)
Lymnaea acuminata		96 h LC50		5.97	Khangarot et al (1982)
Lymnaea emarginata		48 h LC50		34.8	Cairns Jr. et al. (1976)
Physa integra		48 h LC50		0.66	Cairns Jr. et al. (1976)
Polychaetes
Acolosoma haedlyi		48 h LC50		8.6	Cairns Jr. et al. (1978)
Enchytreaus albidus		96 h LC50		0.67	Roembke and Knacker (1989)
Rotifers
Philodina acuticumis		48 h LC50		29	Cairns Jr. et al. (1978)
Philodena roseola		96 h LC50		5.5b	Schaefer and Pipes (1973)
Salt water
Crustaceans
Allorchestes compressa		96 h LC50		5.56	Ahsanullah (1982)
Artemia sp		24 h LC50		13.7	Vanhaeke and Persoone (1981)
Artemia salina		24 h LC50 48 h LC50		7.8 7.9b	Persoone et al. (1989) Kissa et al. (1984)
Callinectes sapidus*		96 h LC50		34	Frank and Robertson (1979)
Cancer magister		96 h LC50		3.44	Martin et al. (1981)
Corophium volutator		96 h LC50		4.4	Bryant et al. (1981)
Mysidopsis almyra		48 h EC50		5.13	Dorn et al. (1987)
Mysidopsis bahia		48 h EC50		2.03 6.0c	Lussier et al. (1985) Jop et al. (1987)
Nitocra spinipes*		96 h LC50		5.7	Lindén et al. (1979)
Palaemonetes pugio		96 h LC50		4.86c	Conklin et al. (1983)
Praunus fluxuosus		96 h LC50		10	McLusky and Hagerman (1987)
Tisbe holothuriae		48 h LC50		8.1b	Moraitou-Apostolopoulou and Veriopoulos (1982)
Molluscs
Crassostrea gigas		48 h EC50		4.54	Martin et al. (1981)
Mathoma balthica		96 h LC50		29	Bryant et al. (1984)
Rangia cuneata		96 h TLm		14	Olson and Harrel (1973)
Polychaetes
Capitella capitata		96 h LC50		5.0a	Reish et al. (1976)
Neanthes arenaceodentata		7 d LC50		1.63	Mearns et al. (1976)
Nereis diversicolor		96 h LC50		7.5	Bryant et al. (1984)
Rotifer
Branchionus plicatilis*		24 h LC50		51.6	Persoone et al. (1989)

Notes:

All results are from tests with potassium dichromate except:

a sodium dichromate;

b sodium chromate;

c potassium chromate.

All concentrations as Cr. * - tested in brackish water

Validity criteria fulfilled:

yes

Conclusions:

Based on a comprehensive review of existing data in the EU RAR, an acceptable assessment of the acute toxicity of chromium (VI) is achieved.

Executive summary:

Potassium dichromate is recommended as a reference substance in the acute toxicity to Daphnia test (Method C.2; EEC, 1992). A ring test involving 129 EC50 determinations from 46 laboratories determined the mean 24h-EC50 value as 1.5 mg K2Cr2O7/l (EEC, 1992). This is equivalent to an EC50 of 0.53 mg Cr/l, expressed on a concentration of chromium basis. The toxicity of chromium (VI) to invertebrates in short-term tests appears to depend on water properties such as hardness, pH and temperature. Persoone et al. (1989) noted decreasing EC50 values for Daphnia magna with decreasing hardness and with increasing temperature. Although the conditions included some which were outside those recommended, checks were carried out to make sure that they did not cause mortality or stress in the controls.

For some invertebrates, toxicity data is available for more than one of the chromium (VI) compounds included in this assessment. The limited available information indicates that, when expressed on a total chromium concentration, there are no significant differences between the toxicity of sodium chromate, sodium dichromate and potassium dichromate (allowing for differences in water properties). This is as would be expected if the equilibria between the chromate and dichromate anions are established in the test medium. Little information is available for ammonium dichromate and chromic acid, but it would be expected that their toxicity would be similar to that of the other chromates/dichromates, when expressed on a total chromium concentration basis.

Reference 2

Endpoint:

short-term toxicity to aquatic invertebrates

Type of information:

experimental study

Adequacy of study:

key study

Study period:

not specified

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

test procedure in accordance with national standard methods with acceptable restrictions

Qualifier:

according to guideline

Guideline:

other: ASTM: Standard practice for conducting acute toxicity tests with fishes, macroinvertebrates, and amphibians.

Version / remarks:

published 1980,
ASTM Designation E 729-80

Deviations:

yes

Remarks:

missing information: number of concentrations, spacing factor, sampling and analytical method description

Principles of method if other than guideline:

24h-old post-larvae from inhouse culture were randomly distributed to exposure cups, which were placed in every test chamber in a continuous-flow through test system for 96 hours. Stock solutions of test material were metered at a constant rate with a peristaltic pump and samples from the test chambers were taken and analysed twice a week to verify test concentrations.

GLP compliance:

not specified

Analytical monitoring:

yes

Details on sampling:

- Concentrations: each concentration and the control, not further specified
- Sampling method: water samples were taken from each test chamber, procedure of sampling not described

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Method: Test material stock solutions were prepared in deionised water at one hundred times the final desired concentration. The stock solutions were metered at a constant rate with a peristaltic pump, and proportionally diluted (1:100) with 15 µm filtered sea water immediately before entering the test chambers.
- Controls: yes, preparation not described
- Test concentration separation factor: not specified

Test organisms (species):

Americamysis bahia (previous name: Mysidopsis bahia)

Details on test organisms:

TEST ORGANISM
- Common name: mysid, oppossum shrimp
- Age at study initiation (mean and range, SD): 24 hrs old
- Stage and instar at study initiation: post-larvae
- Method of breeding: Mysids were cultured for several generations in flow-through 76L glass aquaria. Cultures were continuously supplied with filtered (15 µm) natural sea water at a rate of 100 mL/min, resulting in a 99% volume exchange every 24 h. The outflows were covered by Nitex screen (250 µm) to prevent the escape of mysids or food organisms. Undergravel filters were used with a dolomite substrate 2.54 cm deep to maintain a pH of 7.8-8.2. The dolomite was covered by 2.54cm of beach sand, the preferred substrate for these epibenthic animals. The sand was prewashed in deionized water and muffled at 260 °C for 6 h to remove organic material.
- Source: originally supplied by the EPA Environmental Research Laboratory at Gulf Breeze, Florida
- Feeding during test: yes
- Food type: nauplii of Artemia salina
- Amount: 7*10^4 nauplii for each 76 L culture (approximately 47 nauplii/mysid)
- Frequency: 24 h post hatch 7*10^2 nauplii of Artemia salina per day in each exposure cup

ACCLIMATION
- Acclimation period: 5 days
- Acclimation conditions (same as test or not): The animals were acclimated from 23 ppt salinity to 30 ppt salinity by gradually adding filtered (15 µm) natural sea water over a five-day period so that salinity did not vary more than 2 ppt per 24 h. Sea water was heated to maintain the temperature at 23+/-2 °C.

Test type:

flow-through

Water media type:

saltwater

Limit test:

no

Total exposure duration:

96 h

Test temperature:

20-25°C water temperature

Salinity:

30+/-2 mg/kg

Nominal and measured concentrations:

not specified

Details on test conditions:

TEST SYSTEM
- Test vessel: exposure cups
- Material, size, headspace, fill volume: not specified
- Volume of solution: not specified
- Type of flow-through (e.g. peristaltic or proportional diluter): peristaltic
- Renewal rate of test solution (frequency/flow rate): 50% exchange of volume every 4 h, 30 mL/min inflow, 100 mL/min outflow
- No. of organisms per vessel: 5
- No. of vessels per concentration (replicates): 6
- No. of vessels per control (replicates): 6

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: natural sea water, filtered (15 µm)
- Salinity: 30+/-2 mg/kg
- Culture medium different from test medium: no

OTHER TEST CONDITIONS
- Photoperiod: 12:12 hrs cycle
- Light intensity: 1000 lux

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
- The effect parameter measured was mortality/survival.

Key result

Duration:

96 h

Dose descriptor:

LC50

Effect conc.:

2 030 µg/L

Nominal / measured:

not specified

Conc. based on:

element

Remarks:

chromium(VI)

Basis for effect:

mortality

Remarks on result:

other: 95%-confidence intervals: 1560-2450 µg/L

Details on results:

- Mortality of control: 0% (control survival in all 96h tests was 100%)

Reported statistics and error estimates:

Acute effects are reported as 96h LC50 values and are calculated by probit analysis or the moving average method (Stephan, 1977).

Validity criteria fulfilled:

not specified

Conclusions:

A study was performed with the estuarine mysid shrimp, Mysidopsis bahia, exposed to potassium dichromate for a test duration of 96 h using flow-through test conditions. The study is well documented and meets generally accepted scientific principles, wherefore it is considered to be acceptable for the assessment of the acute toxicity of the registered substance to aquatic invertebrates.
Results were obtained by using established statistical methods that were suitable for the evaluation of the data set, wherefore the LC50 value can be considered as reasonable. No effects were observed in the control which shows a good performance of the study. Based on the obtained results the 96h-LC50 was determined to be 2030 µg/L based on the element Chromium.

Executive summary:

Acute and whole life-cycle toxicity tests were conducted with the estuarine mysid shrimp, Mysidopsis bahia, exposed to selected heavy metals, one of them being potassium dichromate. The tests were conducted with test organisms of laboratory cultures under standardised test conditions in a flow-through system. The test concentrations were analytically monitored. Acute effects were reported as 96h-LC₅₀ values (the estimated concentration at which 50% of the test organisms survived at 96h), calculated by probit analysis or the moving average method. Based on the obtained results the 96h-LC50 for Mysidopsis bahia was determined to be 2030 µg/L based on the element Chromium.

Description of key information

1) Key_ Short-term toxicity to aquatic invertebrates by summary of data from European Union Risk Assessment Report: chromium trioxide, sodium chromate, sodium dichromate, ammonium dichromate and potassium dichromate

3rd. Priority List; Volume 53: mean 24h-EC50 value as 1.5 mg K₂Cr₂O₇/L, equivalent to an EC50 of 0.53 mg Cr/L, determined in a ring test involving 129 EC50 determinations from 46 laboratories

2) Key_Short-term toxicity to aquatic invertebrates: LC50 (96h) = 2030 µg/L (based on Cr) for Mysodopsis bahia exposed to potassium dichromate (flow-through, saltwater, test design according to ASTM Designation E 729-80)

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates

Dose descriptor:

EC50

Effect concentration:

0.53 mg/L

Additional information

1) Potassium dichromate is recommended as a reference substance in the acute toxicity to Daphnia test (Method C.2; EEC, 1992). A ring test involving 129 EC50 determinations from 46 laboratories determined the mean 24h-EC50 value as 1.5 mg K2Cr2O7/l (EEC, 1992). This is equivalent to an EC50 of 0.53 mg Cr/l, expressed on a concentration of chromium basis. The toxicity of chromium (VI) to invertebrates in short-term tests appears to depend on water properties such as hardness, pH and temperature. Persoone et al. (1989) noted decreasing EC50 values for Daphnia magna with decreasing hardness and with increasing temperature. Although the conditions included some which were outside those recommended, checks were carried out to make sure that they did not cause mortality or stress in the controls.

For some invertebrates, toxicity data is available for more than one of the chromium (VI) compounds included in this assessment. The limited available information indicates that, when expressed on a total chromium concentration, there are no significant differences between the toxicity of sodium chromate, sodium dichromate and potassium dichromate (allowing for differences in water properties). This is as would be expected if the equilibria between the chromate and dichromate anions are established in the test medium. Little information is available for ammonium dichromate and chromic acid, but it would be expected that their toxicity would be similar to that of the other chromates/dichromates, when expressed on a total chromium concentration basis.

2) Acute and whole life-cycle toxicity tests were conducted with the estuarine mysid shrimp, Mysidopsis bahia, exposed to selected heavy metals, one of them being potassium dichromate. The tests were conducted with test organisms of laboratory cultures under standardised test conditions in a flow-through system. The test concentrations were analytically monitored. Acute effects were reported as 96h-LC₅₀ values (the estimated concentration at which 50% of the test organisms survived at 96h), calculated by probit analysis or the moving average method. Based on the obtained results the 96h-LC50 for Mysidopsis bahia was determined to be 2030 µg/L based on the element Chromium.