Chromium hydroxide sulphate

Toxicity to aquatic algae and cyanobacteria

Link to relevant study record(s)

Reference

Endpoint:

toxicity to aquatic algae and cyanobacteria

Type of information:

experimental study

Adequacy of study:

key study

Study period:

96 hours

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

data from handbook or collection of data

Qualifier:

according to guideline

Guideline:

other: Protocol for bioassessment of hazardous waste sites. EPA-600/2-83-05

Principles of method if other than guideline:

96 hours exposure period

GLP compliance:

no

Specific details on test material used for the study:

Chromium chloride used as a reference, but analysis and results all expressed as Cr3+

Analytical monitoring:

yes

Details on sampling:

Detaills not described

Vehicle:

no

Test organisms (species):

Raphidocelis subcapitata (previous names: Pseudokirchneriella subcapitata, Selenastrum capricornutum)

Details on test organisms:

Algal cells (10,000 cells/ml) were exposed to the test solutions for 96 h. Algae cultured in algal assay medium served as the controls.

Test type:

static

Water media type:

freshwater

Remarks:

Natural water, contaminated with Chromium

Limit test:

no

Total exposure duration:

96 h

Remarks on exposure duration:

This exceeds normal guidelines for 72 hour exposure. This should not greatly impact on the results in since this is a satable inorganic substance.

pH:

Samples on which algal assays were performed were adjusted with 0.1 N NaOH, as necessary, to a final pH that ranged from 5.6 to 8.9

Duration:

96 h

Dose descriptor:

EC50

Effect conc.:

0.3 mg/L

Nominal / measured:

meas. (initial)

Conc. based on:

element

Remarks:

chromium

Basis for effect:

biomass

Key result

Duration:

96 h

Dose descriptor:

EC50

Effect conc.:

ca. 1.2 mg/L

Nominal / measured:

estimated

Conc. based on:

other: Cr (HSO3)x (SO4)y

Basis for effect:

biomass

Details on results:

The research using different contaminated waters resulted in an EC50 range of 0.229 - 0.360 mg/l with a mean of 0.265 mg/l Cr
These have been rounded to 0.3 mg/l Cr.

Reported statistics and error estimates:

Linear regression analysis [9] was used to calculate the mean inhibitory concentrations (EC50) related to measured chromium concentrations.The difference in yields between the control and test flasks was calculated and reported as percent inhibition.

Validity criteria fulfilled:

not specified

Conclusions:

Water from a number of contaminated sources was assessed for toxicity and a relatively consistant EC50 determined of ca 0.3 mg/l Cr

Executive summary:

Peer reviewed research using scientifically valid methods determined the inhibitory concentrations of Cr3+ to algea

Estimed EC50 for Cr (HSO4)x (SO4)y is 1.2 mg/l (based on nominal molecular weight 210)

Description of key information

Although chromium salts are potentially inhibitory to algal growth in laboratory tests, under environmental conditions the solubility of Cr3+ is considered too low to cause adverse effects. Under environmental conditions, expesically in areas of hard water, the highly insoluble hydroxide will form.

Key value for chemical safety assessment

EC50 for freshwater algae:

1.2 mg/L

Additional information

Based on Cr3+ EC50 0.3 mg/l and nominal molecular weight 210 of the registered substance