Barium oxide, obtained by calcining witherite

Toxicity to aquatic algae and cyanobacteria

Administrative data

Endpoint:

toxicity to aquatic algae and cyanobacteria

Type of information:

migrated information: read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

key study

Study period:

January 1985 - January 1986

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Study well documented, meets generally accepted scientific principles, acceptable for assessment.

Data source

Reference

Reference 1

Reference Type:

publication

Title:

Site-specific barium toxicity to common duckweed, Lemna minor

Author:

Wang W.

Year:

1988

Bibliographic source:

Aquatic Toxicology, 12 (1988) 203-212

Reference 2

Reference Type:

secondary source

Title:

Barium and barium compounds

Author:

World Health Organization

Year:

2001

Bibliographic source:

Concise International Chemical Assessment Document 33. World Health Organisation (Geneva)

Materials and methods

Test guideline

Qualifier:

no guideline followed

Principles of method if other than guideline:

The duckweed tests were conducted as described in Wang, W. Toxicity tests of aquatic pollutants by using common duckweed. Environ. Poll. Ser. B) 11, 1-1, 1986

GLP compliance:

no

Test material

Test material information

Constituent 1

Reference substance name:

Barium chloride

EC Number:

233-788-1

EC Name:

Barium chloride

Cas Number:

10361-37-2

IUPAC Name:

barium dichloride

Sampling and analysis

Analytical monitoring:

yes

Test solutions

Vehicle:

no

Details on test solutions:

A series of Ba solutions were prepared in concentrations of 400, 220, 121, 67, 37, 20 and 11 mg/L

Test organisms

Test organisms (species):

other: Lemna minor

Details on test organisms:

The duckweed culture, L. minor, was originally collected from the field and has been maintained in the laboratory for more than five years

Study design

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

96 h

Test conditions

Hardness:

Range: 37 - 400 mg CaCO3/L (59 water samples from 18 Stations)

Test temperature:

25 - 28 °C

pH:

Range: 6.32 - 8.34 (59 water samples from 18 Stations)

Dissolved oxygen:

Not reported

Nominal and measured concentrations:

Nominal concentrations of 400, 220, 121, 67, 37, 20 and 11 mg/L. Analytical measurements showed that the Ba content was 95% of the nominal concentration. Seven tests were conducted also at a maximum and minimum Ba concentrations of 200 and 5.5 mg/L respectively using duckweed growth medium

Results and discussion

Effect concentrations

Effect concentrations 1

Duration:

96 h

Dose descriptor:

IC50

Effect conc.:

102 mg/L

Nominal / measured:

nominal

Conc. based on:

element

Basis for effect:

growth rate

Remarks on result:

other: Mean value of the sample from Hayes Creek (maximum of observed Ba toxicity)

Effect concentrations 2

Duration:

96 h

Dose descriptor:

IC50

Effect conc.:

> 400 mg/L

Nominal / measured:

nominal

Conc. based on:

element

Basis for effect:

growth rate

Remarks on result:

other: Mean value of the sample from Beaucoup Creek (minimum of observed Ba toxicity)

Effect concentrations 3

Duration:

96 h

Dose descriptor:

IC50

Effect conc.:

25 mg/L

Nominal / measured:

nominal

Conc. based on:

element

Basis for effect:

growth rate

Remarks on result:

other: 95% CL: 18 - 33 mg/L. The Inhibition concentration refers to test conducted in ducweed medium in place of water samples

Applicant's summary and conclusion

Conclusions:

The results shows that Ba toxicuty is highly dependent on site-specific water quality. The major factor modifying Ba toxicity was the sulfate concentration in the water samples.