Silicic acid, titanium salt

Toxicity to aquatic algae and cyanobacteria

Administrative data

Endpoint:

toxicity to aquatic algae and cyanobacteria

Type of information:

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

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Guideline study with accepatble restrictions

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

1999

Report date:

1999

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 201 (Alga, Growth Inhibition Test)

GLP compliance:

no

Test material

Test material information

Constituent 1

Reference substance name:

Automatically generated during migration to IUCLID 6, no data available

IUPAC Name:

Automatically generated during migration to IUCLID 6, no data available

Details on test material:

- Name of test material (as cited in study report): Shieldex AC 3
- Substance type: calcium ion-exchanged amorphous silica
- Physical state: white powder

Sampling and analysis

Analytical monitoring:

no

Test solutions

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Eluate: the test substance (different concentrations) was suspended in deionised water and shaken for 24 h (130 rpm). After this incubation the suspensions were filtered via fluted filter. The resulting eluates were used directly in the algae test (without dilution).

Test organisms

Test organisms (species):

Desmodesmus subspicatus (previous name: Scenedesmus subspicatus)

Details on test organisms:

TEST ORGANISM
- Strain: CHODAT, No. 8681
- Source (laboratory, culture collection): plant physiology institut of the university Goettingen, Germany

Study design

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

72 h

Test conditions

Hardness:

no data

Test temperature:

25 +/- 1 ° C

pH:

8.29 - 9.97 (controls)
8.35 - 9.43 (treatments)

Dissolved oxygen:

no data

Nominal and measured concentrations:

1000, 800, 400, 200 and 100 mg/l (nominal, Eluat))

Details on test conditions:

TEST SYSTEM
- Control end cells density: 3.32*10E6
- No. of organisms per vessel: approx. 7.2*10E6 cells/ml
- No. of vessels per concentration (replicates): 5
- No. of vessels per control (replicates): 7

GROWTH MEDIUM
- The eluates were enriched with the necessary nutrient salts.

OTHER TEST CONDITIONS
- Adjustment of pH: no
- Photoperiod: continuous lightning
- Light intensity and quality: > 120 µE/m2s
- the vessels were shaken 15 minutes per hour

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
- Determination of cell concentrations: spectrophotometric at 578 nm. Blank value correction with 3 replicates without algae inoculum.

TEST CONCENTRATIONS
- Spacing factor for test concentrations: geometric series
- Range finding study
- Test concentrations: 10, 1 and 0.1 g/l
- Results used to determine the conditions for the definitive study: not available

Reference substance (positive control):

no

Results and discussion

Effect concentrations

Effect concentrations 1

Duration:

72 h

Dose descriptor:

EC10

Effect conc.:

41 mg/L

Nominal / measured:

nominal

Basis for effect:

growth rate

Remarks on result:

other: eluate

Effect concentrations 2

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

2 500 mg/L

Nominal / measured:

nominal

Basis for effect:

growth rate

Remarks on result:

other: eluate

Effect concentrations 3

Duration:

72 h

Dose descriptor:

EC10

Effect conc.:

33 mg/L

Nominal / measured:

nominal

Basis for effect:

biomass

Remarks on result:

other: eluate

Effect concentrations 4

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

410 mg/L

Nominal / measured:

nominal

Basis for effect:

biomass

Remarks on result:

other: eluate

Any other information on results incl. tables

Cell density at the start of the experiment: approx. 7.2*10E4 cells/mL.

Cell density after 72 h and inhibition of the growth rate and the biomass were shown in the following table:

concentration [mg/L]	cell density after 72 h [cells/mL]	inhibition of growth rate (%]	inhibition of biomass [%}
control	3.32*10E6	0	0
1000	8.38*10E5	39.8	68.1
800	9.37*10E5	36.9	63.2
400	1.48*10E6	34.6	44.3
200	2.00*10E6	30.2	27.4
100	1.98*10E6	14.5	37.4

No information about the mean coefficient of variation for section-by-section specific growth rates (days 0-1, 1-2 and 2-3, for 72-hour tests) in the control cultures and about the coefficient of variation of average specific growth rates during the whole test period in replicate control cultures available. So it was not possible to evaluate if all validity criteria were fullfilled.