Potassium chromate

Toxicity to aquatic plants other than algae

Administrative data

Endpoint:

toxicity to aquatic plants other than algae

Type of information:

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

Adequacy of study:

key study

Study period:

1983 to 1985

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: see 'Remark'

Remarks:

The EU RAR summarises the results of two studies which have limitations regarding study design and reliability. However, the results of these studies, on four species, combined with data on algae, provide an adequate assessment of toxicity to primary producers in the aquatic compartment.

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:

Two studies on four species, collectively, provide an adequate assessment of toxicity to aquatic plants.

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:

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 3

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

Details on test material:

No further details provided

Sampling and analysis

Analytical monitoring:

yes

Details on sampling:

Range of methods used

Test solutions

Vehicle:

no

Details on test solutions:

Range of media used

Test organisms

Test organisms (species):

other: Lemna gibba, Lemna minor, Spirodela polyrhiza and Spirodela punctata

Study design

Test type:

other: Different test designs

Water media type:

freshwater

Limit test:

no

Remarks on exposure duration:

Range used

Post exposure observation period:

Not indicated

Test conditions

Hardness:

Range from different tests

Test temperature:

Range from different tests

pH:

Range from different tests

Dissolved oxygen:

Range from different tests

Salinity:

Range from different tests

Nominal and measured concentrations:

Range from different tests

Details on test conditions:

Range from different tests

Reference substance (positive control):

no

Results and discussion

Effect concentrations

Remarks on result:

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

Any other information on results incl. tables

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

Species	Endpoint: growth (g) biomass (b)	Value (mg/L)	Reference
Lemna gibba	8 d NOEC (g)	0.1b,d	Staves and Knaus (1985)
Lemna minor	7 d NOEC (g)	0.11	Sloof and Canton (1983)
Spirodela polyrhiza	8 d NOEC (g)	0.1b,d	Staves and Knaus (1985)
Spirodela punctata	8 d NOEC (g)	0.5a,b,d	Staves and Knaus (1985)

a NOEC calculated as LOEC/2 from paper, effect of 14%; (b) - biomass; (g) ¿ growth

b sodium chromate tested; all others used potassium dichromate. All concentrations as Cr.

d study rated as IIIb

Applicant's summary and conclusion

Validity criteria fulfilled:

yes

Conclusions:

Based on a review of data on algae and aquatic plants, the data from the EU RAR provides an acceptable assessment of toxicity to aquatic primary producers.

Executive summary:

From two studies with four species, the 7 to 8 day NOEC values (growth) to aquatic plants range from 0.1 to 0.5 mg/L, based on tests with potassium dichromate and sodium chromate.

Where comparison is possible, the toxicity of sodium chromate or sodium dichromate, when expressed on a total chromium basis, does not appear to be significantly different from that of potassium dichromate. 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.