Chromium trioxide

Short-term toxicity to fish

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

short-term toxicity to fish

Type of information:

experimental study

Adequacy of study:

supporting study

Study period:

From 1954 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 fish acute studies which, individually, have limitations regarding study design and reliabilty. However the results of these studies when taken as a whole, provide an adequate assessment of acute toxicity to fish. 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 (96 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

Principles of method if other than guideline:

Several studies, collectively, provide a weight-of-evidence to address the acute toxicity endpoint. The methods include the appropriate endpoints (lethality and sublethal effects) and duration (equal to 96 hours exposure). Results from more species than recommended have been reported and hence provide an adequate representation of acute toxicity to fish.

GLP compliance:

no

Analytical monitoring:

yes

Details on sampling:

Various sampling procedures based on multiple studies

Vehicle:

no

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

Details on test organisms:

Range of species tested

Test type:

other: Range of test designs used

Water media type:

freshwater

Limit test:

no

Remarks on exposure duration:

Range used from several studies

Post exposure observation period:

None reported

Hardness:

Range used from several studies

Test temperature:

Range used from several studies

pH:

Range used from several studies

Dissolved oxygen:

Range used from several studies

Salinity:

Range used from several studies

Nominal and measured concentrations:

Range used from several studies

Details on test conditions:

Range used from several studies

Reference substance (positive control):

not specified

Duration:

96 h

Dose descriptor:

LC50

Effect conc.:

13 mg/L

Nominal / measured:

nominal

Conc. based on:

element

Basis for effect:

other: see table below

Remarks on result:

other: see table below

Details on results:

See any other information below.

Sublethal observations / clinical signs:

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

Species	Endpoint	Value (mg/l)	Reference
Freshwater
Brachydanio rerio	96-hour LC50	58.5	Bellavere and Gorbi (1981)
Carrasius auratus	96-hour LC50	37.5	Pickering and Henderson (1966)
Channa punctatus	96-hour LC50	45.2	Saxena and Parashari (1983)
Colisa fasciatus	96-hour LC50	20.8c	Srivastava et al. (1979)
Ictalurus punctatus	24-hour LC50	58	Cairns Jr. et al (1978)
Lebistes reticulatus	96-hour TLm	30	Pickering and Henderson (1966)
Lepomis macrochirus	96-hour LC50 48-hour TLm 96-hour LC50	110 213a 120b	Trama and Benoit (1960) Turnbull et al. (1954) Cairns Jr. and Scheier (1958)
Morone saxitalis	96-hour LC50	28b	Palawski et al. (1985)
Notemigonus crysoleucas	96-hour LC50	55	Hartwell et al. (1989)
Oncorhynchus mykiss	96-hour LC50	63.6 69a 13d	Brown et al. (1985) Benoit (1976) Van Der Putte et al (1981b)
Pimephales promelas	96-hour TLm 96-hour LC50 96-hour TLm	17.6 33.2a 45.6b	Pickering and Henderson (1966) Benoit (1976) Pickering and Henderson (1966)
Salvelinus fontinalis	96-hour LC50	59	Benoit (1976)
Saltwater
Alburnus alburnus*	96-hour LC50	84.8	Lindén et al. (1979)
Chelon labrosus	48-hour LC50	47.2	Taylor et al. (1985)
Citlerichthys stigmaeus	96-hour LC50	30	Mearns et al. (1976)
Cyprinodon variegates	96-hour LC50	25 21.4b	Jop et al. (1987) Dorn et al. (1987)
Gasterosteus aculcatus*	96-hour LC50	33 35b	Jop et al. (1987)
Limanda limanda	96-hour LC50	47	Taylor et al. (1985)

Validity criteria fulfilled:

yes

Conclusions:

Based on a review of existing fish data from the EU RAR, an acceptable assessment of acute toxicity was achieved.

Executive summary:

Based on a review of existing fish data from the EU RAR, an acceptable assessment of acute toxicity was achieved.

The acute toxicity of chromium (VI) to fish appears to be dependent on the water hardness and also pH. Higher toxicity has generally been seen in soft water and at more acidic pHs, particularly those <6.5. This dependence appears to follow a similar pattern to the uptake of chromium (VI) by fish (see Section 3.1.1.2.4), where it has been postulated that at lower pHs, the main form of chromium (VI) in solution is the monovalent HCrO4 - ion, which has been postulated as having a higher mobility across cell membranes than the divalent chromium (VI) oxyanions found at higher pH.

For some fish species, toxicity data are available for more than one of the chromium (VI) compounds included in this assessment. The 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 fish

Type of information:

experimental study

Adequacy of study:

key study

Study period:

not specified

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:

Static experiments in which Danio rerio fish were exposed to 7 concentrations of chromium(VI) were run for 96 hours. All tests were carried out in dilution water (distilled water supplemented with salts) and at a constant temperature (20°C). Oxygen saturation and pH were checked during each experiment and did not decrease significantly until the end of the test. In the analysis the salt potassium dichromate was used. Mortality was checked every 24 hours.

GLP compliance:

not specified

Remarks:

before GLP was standard

Analytical monitoring:

yes

Vehicle:

not specified

Details on test solutions:

not given

Test organisms (species):

Danio rerio (previous name: Brachydanio rerio)

Details on test organisms:

TEST ORGANISM
- Common name: zebrafish
- Source: commercial, aquarist shops
- Length at study initiation (length definition, mean, range and SD): 3.5 +/- 0.5 cm

ACCLIMATION
- Acclimation period: 30 days
- Health during acclimation (any mortality observed): The fish were used only if, at the end of acclimation period, they did not exhibit malformations or apparent signs of stress.

Test type:

static

Water media type:

freshwater

Remarks:

dilution water prepared from distilled water

Limit test:

no

Total exposure duration:

96 h

Hardness:

100 mg/L as CaCO3

Test temperature:

20 °C

pH:

7.8

Dissolved oxygen:

always close to saturation level, >=90%

Nominal and measured concentrations:

not specified

Details on test conditions:

TEST SYSTEM
- No. of organisms per vessel: 10
- No. of vessels per concentration (replicates): 3
- No. of vessels per control (replicates): 3

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: distilled water mixed with six salts (please refer to section "Any other information on materials and methods incl. tables" for further information), aerated for 24 hours
- Culture medium different from test medium: no

EFFECT PARAMETERS MEASURED (with observation intervals if applicable):
- Mortality assessed every 24 hrs

TEST CONCENTRATIONS
- Range finding study/Test concentrations: Preliminary tests were made and for each of the toxicants a set of seven concentrations was determined in the range from the highest not causing mortality to the lowest causing 100% mortality.

Key result

Duration:

96 h

Dose descriptor:

LC50

Effect conc.:

58.5 mg/L

Nominal / measured:

nominal

Conc. based on:

element

Basis for effect:

mortality (fish)

Duration:

72 h

Dose descriptor:

LC50

Effect conc.:

58.5 mg/L

Nominal / measured:

nominal

Conc. based on:

element

Basis for effect:

mortality (fish)

Duration:

48 h

Dose descriptor:

LC50

Effect conc.:

67 mg/L

Nominal / measured:

nominal

Conc. based on:

element

Basis for effect:

mortality (fish)

Duration:

24 h

Dose descriptor:

LC50

Effect conc.:

96 mg/L

Nominal / measured:

nominal

Conc. based on:

element

Basis for effect:

mortality (fish)

Duration:

12 h

Dose descriptor:

LC50

Effect conc.:

128 mg/L

Nominal / measured:

nominal

Conc. based on:

element

Basis for effect:

mortality (fish)

Duration:

8 h

Dose descriptor:

LC50

Effect conc.:

183 mg/L

Nominal / measured:

nominal

Conc. based on:

element

Basis for effect:

mortality (fish)

Reported statistics and error estimates:

The LC50 have been computed using the method of Litchfield and Wilcoxon (1949).

Validity criteria fulfilled:

not specified

Conclusions:

An acute toxicity study was performed with the zebrafish (Brachydanio rerio) exposed to potassium dichromate for a test duration of 96 h using static 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 fish.
Under the conditions used for the test the toxicity of chromium to zebrafish increased over time shown by a constant decrease in LC50 values until 72 hours exposure time. As the standard deviations are approx. equal at all control times, the results can be considered reliable. Based on the obtained results, the 96h LC50 was determined to be nominal 58.5 mg/L. Thus, the obtained LC50 values of chromium(VI) to B. rerio are generally in agreement with those found by other authors.

Executive summary:

The acute toxicity of the test substance to fish was investigated in the above study. Brachydanio rerio (zebra fish) was used as test organism and exposed to seven nominal test concentrations causing 0 - 100% effects for 96 hours of test duration under static test conditions. A control was running in parallel containing dilution water only. The test was carried out at a temperature of 20°C, with a pH of 7.8 and an oxygen concentration above the saturation concentration ( ≥ 90% ASV) throughout the test. Based on the obtained results, the 96h LC₅₀ was determined to be nominal 58.5 mg/L.

Description of key information

1) Key_ Short-term toxicity to fish 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: LC50 (96h) = 13 - 120 mg/L (nominal) for several species from various studies

2) Key_Short-term toxicity to fish: LC₅₀(96h) = 58.8 mg/L (nominal) for Potassium dichromate exposed to Brachydanio rerio (static, freshwater, no guideline followed)

Key value for chemical safety assessment

Fresh water fish

Fresh water fish

Dose descriptor:

LC50

Effect concentration:

13 mg/L

Additional information

1) Based on a review of existing fish data from the EU RAR, an acceptable assessment of acute toxicity was achieved.

The acute toxicity of chromium (VI) to fish appears to be dependent on the water hardness and also pH. Higher toxicity has generally been seen in soft water and at more acidic pHs, particularly those <6.5. This dependence appears to follow a similar pattern to the uptake of chromium (VI) by fish (see Section 3.1.1.2.4), where it has been postulated that at lower pHs, the main form of chromium (VI) in solution is the monovalent HCrO4 - ion, which has been postulated as having a higher mobility across cell membranes than the divalent chromium (VI) oxyanions found at higher pH.

For some fish species, toxicity data are available for more than one of the chromium (VI) compounds included in this assessment. The 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) The acute toxicity of the test substance to fish was investigeted in the above study. Brachydanio rerio (zebra fish) was used as test organism and exposed to seven nominal test concentrations causing 0 - 100% effects for 96 hours of test duration under static test conditions. A control was running in parallel containing dilution water only. The test was carried out at a temperature of 20°C, with a pH of 7.8 and an oxygen concentration above the saturation concentration ( ≥ 90% ASV) throughout the test. Based on the obtained results, the 96h LC50 was determined to be nominal 58.8 mg/L.