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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:

72 hours

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Justification for type of information:

Guideline study with supporting analysis

Qualifier:

according to guideline

Guideline:

OECD Guideline 201 (Freshwater Alga and Cyanobacteria, Growth Inhibition Test)

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

yes

Vehicle:

no

Remarks:

Water soluble

Test organisms (species):

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

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

72 h

Hardness:

Equivalent 50 mg/l hardness, based on calcium, magnesium salts (including sulphates)

Test temperature:

22 - 23 C

pH:

Range pH 8 - 8.2, showing a slight rise in pH during the course of the study

Nominal and measured concentrations:

Nominal 0, 3.2, 6.1, 11.7, 22.3, 42.1 80 mg/l
Recovery of the test material ranged from 93 - 112 % of nominal.
The results are expressed as nominal

Duration:

72 h

Dose descriptor:

IC10

Effect conc.:

11.47 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

IC50

Effect conc.:

37.58 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

IC10

Effect conc.:

5.6 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

yield

Duration:

72 h

Dose descriptor:

IC50

Effect conc.:

13.6 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

yield

Validity criteria fulfilled:

yes

Conclusions:

The IrC50 based on growth rate was measured to be ca 38 mg/l/
On the basis that toxicity is linked to Mn, the Mn IrC is 9.1 mg/l at a water hardness of 50 mg/l. The reported IC50 for Mn is in the range 3.8 - 18 mg/l Mn suggesting that this is within the expected range.

Key value for chemical safety assessment

EC50 for freshwater algae:

37.58 mg/L

EC10 or NOEC for freshwater algae:

11.47 mg/L