Potassium chromate

Short-term toxicity to aquatic invertebrates

Administrative data

Endpoint:

short-term toxicity to aquatic invertebrates

Type of information:

migrated information: read-across based on grouping of substances (category approach)

Adequacy of study:

key 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.

Data source

Reference

Reference Type:

review article or handbook

Title:

European Union Risk Assessment Report: chromium trioxide, sodium chromate, sodium dichromate, ammonium dichromate and potassium dichromate

Author:

European Chemicals Bureau

Year:

2005

Bibliographic source:

3rd. Priority List; Volume 53

Materials and methods

Test guideline

Qualifier:

no guideline followed

Principles of method if other than guideline:

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

GLP compliance:

no

Test material

Test material information

Constituent 1

Reference substance name:

Chromium trioxide

EC Number:

215-607-8

EC Name:

Chromium trioxide

Cas Number:

1333-82-0

IUPAC Name:

1333-82-0

Constituent 2

Reference substance name:

Sodium chromate

EC Number:

231-889-5

EC Name:

Sodium chromate

Cas Number:

7775-11-3

Molecular formula:

CrH2O4.2Na

IUPAC Name:

disodium dioxido(dioxo)chromium

Constituent 3

Reference substance name:

Potassium dichromate

EC Number:

231-906-6

EC Name:

Potassium dichromate

Cas Number:

7778-50-9

Molecular formula:

Cr2H2O7.2K

IUPAC Name:

sodium dichromate

Constituent 4

Reference substance name:

Sodium dichromate

EC Number:

234-190-3

EC Name:

Sodium dichromate

Cas Number:

10588-01-9

Molecular formula:

Cr2Na2O7

IUPAC Name:

sodium dichromate

Constituent 5

Reference substance name:

Potassium chromate

EC Number:

232-140-5

EC Name:

Potassium chromate

Cas Number:

7789-00-6

Molecular formula:

CrH2O4.2K

IUPAC Name:

dipotassium dioxochromiumbis(olate)

Details on test material:

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.

Sampling and analysis

Analytical monitoring:

yes

Details on sampling:

Various sampling procedures based on multiple studies

Test solutions

Details on test solutions:

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

Test organisms

Test organisms (species):

other: Range of species tested

Study design

Test type:

other: Range of test designs used

Water media type:

not specified

Post exposure observation period:

None reported

Test conditions

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

Results and discussion

Effect concentrations

Remarks on result:

other: See "Any other information on results incl. tables" below.

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.

Any other information on results incl. tables

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

Applicant's summary and conclusion

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.