Aluminum magnesium vanadium oxide

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:

12 Mar - 20 Aug 2012

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 201 (Alga, Growth Inhibition Test)

Version / remarks:

adopted 23 Mar 2006, Annex 5 corrected 28 Jul 2011

Deviations:

no

Qualifier:

according to guideline

Guideline:

EU Method C.3 (Algal Inhibition test)

Version / remarks:

adopted 24 Aug 2009

Deviations:

no

Qualifier:

according to guideline

Guideline:

other: OECD Guidance No. 23, Document on Aquatic Toxicity Testing of Difficult Substances and Mixtures

Version / remarks:

adopted 14 Dec 2000

GLP compliance:

yes (incl. QA statement)

Remarks:

Rheinland-Pfalz, Landesamt für Umwelt, Wasserwirtschaft ud Gewerbeaufsicht, Mainz, Germany

Analytical monitoring:

yes

Details on sampling:

- Concentrations: all test concentrations

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
One day before start of the test, the test solutions were prepared. This was done by weighing the respective nominal load, i.e. 4.6, 10, 22, 4.6 and 100 mg/L, adding the corresponding amount of dilution water (1000 mL) and shaking vigorously for 24 hours. The resulting solutions were filtrated through 0.45 µm filters. Each treatment loading rate was prepared separately and split into three aliquots for each replicate. In addition a dilution water control was prepared in parallel.

Test organisms (species):

Desmodesmus subspicatus (previous name: Scenedesmus subspicatus)

Details on test organisms:

TEST ORGANISM
- Common name: Green alga.
- Source (laboratory, culture collection): The culture of Desmodesmus subspicatus was obtained in Oct 2011 from MBM Science-bridge GmbH (Institut für Pflanzenphysiologie of Universität Göttingen). The algae are kept as stock culture on solid agar at 8 °C. From the stock culture, a permanent culture was prepared. From an aliquot of the permanent culture, the pre-culture was prepared.
- Age of inoculum (at test initiation): Three days before the start of the test, an aliquot of the stock culture containing a few cells was brought into pre-culture medium and incubated for 72 hours. The resulting culture was growing exponentially. Before usage, the culture was checked on the absence of cell aggregates. After the adjustment to a cell concentration of about 2 - 5 x10^4/mL through photometric measurement and addition of algal medium the culture was usable for the test.

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

72 h

Test temperature:

24 °C

pH:

7.6 to 8.6 in the control and 7.9 – 9.2 in the test solutions

Nominal and measured concentrations:

control, 4.6, 10, 22, 46 and 100 mg/L (nominal)

Details on test conditions:

TEST SYSTEM
- Test vessel:
- Type (delete if not applicable): open
- Material, size, headspace, fill volume: glass flasks 50 mL, fill volume 45 ± 5 mL
- Initial cells density: 2-5 x10^4 cells/mL
- Control end cells density: 7 x10^5 cells/mL
- No. of vessels per concentration (replicates): 3
- No. of vessels per control (replicates): 6

GROWTH MEDIUM
- Standard medium used: yes (OECD medium)

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: deionised water
- Culture medium different from test medium: yes. The algae are kept as stock culture on solid agar.
- Intervals of water quality measurement: temperature each 24h, pH at the start and at the end

OTHER TEST CONDITIONS
- Sterile test conditions: no
- Photoperiod: continuous light
- Light intensity and quality: 4800 lux

EFFECT PARAMETERS MEASURED (with observation intervals if applicable):
- Determination of cell concentrations: spectrophotometer, 440 nm, every 24 hours

TEST CONCENTRATIONS
- Spacing factor for test concentrations: ca. 2.2

Reference substance (positive control):

yes

Remarks:

Potassium dichromate

Key result

Duration:

72 h

Dose descriptor:

EL50

Effect conc.:

> 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat. (dissolved fraction)

Remarks:

loading rate

Basis for effect:

growth rate

Remarks:

, biomass and yield

Key result

Duration:

72 h

Dose descriptor:

NOELR

Effect conc.:

46 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat. (dissolved fraction)

Remarks:

loading rate

Basis for effect:

growth rate

Remarks:

, biomass and yield

Details on results:

- Exponential growth in the control (for algal test): yes
- Observation of abnormalities (for algal test): none
- Any stimulation of growth found in any treatment: Algal growth was higher in the treatments 4.6 to 46 mg/L than in the control. At 100 mg/L a significant inhibition of growth was observed.

Results with reference substance (positive control):

- Results with reference substance valid? yes
- 72h ErC50: 1.40 mg/L

Reported statistics and error estimates:

For the treatments with the nominal test item concentrations 46 mg/L and 100 mg/L , it was tested whether the differences between treatment and control were significant. The values for the area under the curve, Yield and the growth rate were used for the assessment of observed effect levels. In order to select a suitable test for significance, it was checked whether equality of variance was given. If equality of variance was given, the t-test was used; else, the WEIR test was used.

 Table 1: Measured Al concentrations in mg/L

Test concentration (nominal)	Measured Al Conc 0 h	Measured Al Conc 72 h	Recovery	geom. Mean.
mg/L	mg/L	mg/L	%	mg/L
0	< LOQ	< LOQ	-	-
4.6	0.07	0.06	80.88	0.06
10	0.15	0.13	84.31	0.14
22	0.35	0.31	87.57	0.33
46	0.57	0.41	72.13	0.48
100	0.55	0.43	77.84	0.48

LOQ = 0.025 mg/L (after 10 fold enrichment)

Table 2: Results stability in algal test medium (Al), mg/L

Time	Conc. Al mean 1	Conc. Al mean 2	Mean
Oh	1.66	1.70	1.68
72 h	1.54	1.46	1.50
Stability (= Mean 72h / Mean Oh)			89%

Table 3: Results stability in algal test medium (V), mg/L

Time	Conc. V mean 1	Conc. V mean 2	Mean
Oh	0.262	0.273	0.268
72 h	0.278	0.296	0.287
Stability (= Mean 72h / Mean Oh)			107%

Table 4: Cell number/mL in main study

Nominal concentration in mg/L	Parameter	Cell number/mL
		0 h	24 h	48 h	72 h
0	Mean	2206	26104	122065	443406
0	SD	0	3800	12176	22840
4.6	Mean	2206	26472	147434	522822
4.6	SD	0	1103	12688	50630
10	Mean	2206	31252	148905	506645
10	SD	0	4458	25797	40442
22	Mean	2206	28678	129786	503336
22	SD	0	1910	14975	13159
46	Mean	2206	29413	129786	500027
46	SD	0	2547	8279	47982
100	Mean	2206	29413	109197	251484
100	SD	0	1274	23163	87221

Table 5: Growth rate µ, area under the curve AUC, yield

Nom. Concentration in mg/L	Meas. Concentration in mg/L		Growth Rate [day-1]	AUC [Cell Concentration/mL*day]	Yield [Cell Concentration/mL]
0	-	Mean	1.77	364358	441200
		SD	0.02	25178	22840
4.6	0.06	Mean	1.82	429802	520616
		SD	0.03	37834	50630
10	0.14	Mean	1.81	427964	504439
		SD	0.03	45314	40442
22	0.33	Mean	1.81	404617	501130
		SD	0.01	16548	13159
46	0.48	Mean	1.81	403698	497821
		SD	0.03	27426	47982
100	0.48	Mean	1.56	258837	249278
		SD	0.13	65478	87221

 

Table 6: Inhibition values main study

Nominal Concentration in mg/L	% Inhibition
	Growth Rate [x]	Area under the Curve AUC	Yield
0	0!	0!	0!
4.6	-3.07	-17.96	-18.00
10	-2.50	-17.46	-14.33
22	-2.41	-11.05	-13.58
46	-2.23	-10.80	-12.83
100	11.59	28.96	43.50

Description of key information

EL50 (72h, growth rate) > 100 mg/L (nominal, loading rate) (OECD 201, Desmodesmus subspicatus)

NOELR (72h, growth rate) = 46 mg/L (nominal, loading rate) (OECD 201, Desmodesmus subspicatus)

The measured concentrations for Al were 0.06 - 0.48 mg/L (geom. mean)

Key value for chemical safety assessment

EC10 or NOEC for freshwater algae:

46 mg/L

Additional information

One study according to OECD 201 and GLP is available to evaluate the acute toxicity of aluminium magnesium vanadium oxide to freshwater green alga Desmodesmus subspicatus at nominal concentrations ranging from 4.6 to 100 mg/L (2013). The substance has a low water solubility and therefore the test solution was prepared by adding the appropriate test item to 1 liter of dilution water. After shaking vigorously for 24 hours the resulting solution was filtrated through 0.45 μm filters. Following this, the filtrates were used for the main test without dilution. The test solutions included the dilution water control and nominal loading rates of 4.6, 10, 22, 46, and 100 mg/L test item. The corresponding mean measured concentrations for Al were 0.06, 0.14, 0.33, 0.48, 0.48 mg/L (geom. mean measured). Each treatment loading rate was prepared separately and split into four aliquots for each replicate respectively. Al was determined in the test solutions using AAS. The concentrations remained stable in the test medium over the study period of 72 h. In a preliminary limit test with a loading of 100 mg/L vanadium was not detectable in the test solutions at the start of the study. Therefore, it is considered that the vanadium concentration in the test solutions were below the detection limit (0.25 mg/L). As a consequence, in the main test only the Al concentration in the test solutions was determined at the beginning and at the end of the test. The 72h NOELR based on growth rate was determined as 46 mg/L. The corresponding EL50 for the growth rate was determined as > 100 mg/L. LOELR and EL50 are based on nominal loading rates.