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Toxicity to aquatic algae and cyanobacteria

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Endpoint:
toxicity to aquatic algae and cyanobacteria
Type of information:
migrated information: read-across based on grouping of substances (category approach)
Adequacy of study:
disregarded due to major methodological deficiencies
Study period:
1972
Reliability:
3 (not reliable)
Rationale for reliability incl. deficiencies:
other: very little data is provided. no GLP, no guideline, no substance identity
Qualifier:
no guideline followed
Qualifier:
according to guideline
Guideline:
other: ARNON. D. L. 1938. Micronutrient clemcnts in culture solution experiments with higher plants. Am. J. bol. 25:322.
GLP compliance:
not specified
Analytical monitoring:
no
Details on test solutions:
The nutrient solution contained
1.9 g KNO3 , 0.122 g MgSO4·7H2O, 0.07 g' KH2PO4
(8 ppm P). 0.045 g of ferric citrate, ami 0.045 g of citric
acid per liter. Tracc elements were added at onehalf
the concentrations specified in a modified Hoagland
solution. The P level was reduced to 8 ppm because the level contained in the original
solution (71 ppm) would have precipitated much
of the Al added and thus reduced its toxicity.
Aluminium was added at 0, 3, 6, and 12 ppm as
Al2 ( SO4)2*18 H2O, and the pH of each solution was
adjusted to 4.6 before inoculation.
After a growth period of 26 day under continuous
fluorcscent light at 25 C, the cells were
separated by centrifuging at 2500 rpm. and dried to
constant weight. Suspension pH values were measured
at the time of harvest.
Test organisms (species):
Chlorella pyrenoidosa
Details on test organisms:
1, 2 ml aliquots of an algal suspension (C. pyreniodosa, strain 1, fitzgerald).
Test type:
static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
26 d
pH:
4.6
Nominal and measured concentrations:
nominal: 0, 3, 6, 12 ppm Al
Details on test conditions:
After a growth period of 26 day under continuous
fluorcscent light at 25 C, the cells were
separated by centrifuging at 2500 rpm. and dried to
constant weight. Suspension pH values were measured
at the time of harvest.
Reference substance (positive control):
no
Duration:
26 d
Dose descriptor:
EC50
Effect conc.:
5.8 other: ppm
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
biomass
Details on results:
EC 50 determniend by reviewer by mono variable regression
Reported statistics and error estimates:
EC 50 determniend by reviewer by mono variable regression

Al added (ppm)

Yield ( mg/150 ml dw)

Yield response to Al

0

297

-

1.5

358.4

+21

3.0

235

-21

6.0

130.1

-56

12.0

0

-

Validity criteria fulfilled:
not applicable
Conclusions:
The EC50 was determined to be 5.8 ppm. study is not considered reliable because to much data is missing.
Executive summary:

Chlorella pyrenoidosa, a green algae which has no measurable Ca requirement, tolerated much higher Al concentrations in solution than higher plants which require considerable Ca. This algae also gave significant positive yield respons to al concentrations between 1.5 and 12 ppm (added at pH 4.6) the positive Al respons was not attributed to V, Gr, Ni, Co, W or Ti contaminants in the salt.

The EC50 was determined by the reviewer to be 5.8 ppm nominal.

Endpoint:
toxicity to aquatic algae and cyanobacteria
Type of information:
migrated information: read-across based on grouping of substances (category approach)
Adequacy of study:
supporting study
Study period:
1983
Reliability:
4 (not assignable)
Rationale for reliability incl. deficiencies:
other: see 'Remark'
Remarks:
Although no guideline was used, no certificate of analysis was available and study is non GLP. The study is reasonable complete and endpoints were tested along a wide pH path. The data is very usable also, because the Al species were specified. Data can be used in riskassessment, especially when looking at fate. However, because of the lack of a valid guideline/substance identity info and non-GLP it was rated as usable as supporting datapoint
Qualifier:
no guideline followed
Principles of method if other than guideline:
Florence, T. M., Lumsden, B. G., and Fardy, J. J. (1984). Algae as indicators of copper
speciation. In: Kramer, C. J. M., and Duinker, J. C. (eds.), Complexation of Trace
Metals in Natural Waters, pp. 317-327. Martinus Nijhoff/Dr. W. Junk Publishers,
The Hague.
GLP compliance:
not specified
Analytical monitoring:
yes
Vehicle:
no
Details on test solutions:
was then suspended in a small volume of the hard water.
Preparation of solutions for algal assay involved adjusting the pH of 60 mL
of hard water in a siliconised 250-mL conical flask by slowly adding I M HNO3),
with vigorous stirring. An aliquot of the aluminium stock solution
(0.1 g Al L-l in 0.0015 M HN03) was added, the pH readjusted, and the mixture allowed to stand for 24 h,
when the labile/total aluminium concentration ratio became constant.
Test organisms (species):
Chlorella pyrenoidosa
Details on test organisms:
Chlorella pyrenoidosa was cultured in standard MBL medium and for algal
assays an aliquot of the culture was centrifuged, decanted, and washed three times
by centrifuging with a synthetic hard water (0.192 g NaHCO3, 0.120 g
MgSO4, 0.120 g CaSO4.2H2O, and 0.008 g KCI per litre). The final residue of
algae was then suspended in a small volume of the hard water.
Test type:
static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
11 d
Hardness:
0.192 g NaHCO3, 0.120 g MgSO4, 0.120 g CaSO4.2H2O, and 0.008 g KCI per litre
pH:
4.9-7.1
Nominal and measured concentrations:
dissolved Al:<2, <5, 8.5, 10.1, 17.0, 0.5, 22.3, 24.8
Details on test conditions:
The pH and aluminium concentrations were measured before
adding an alifuot of the algal suspension to give an initial cell density of 2-5 x
10^4 cells mL-. An aluminium-free control solution was prepared for each pH
value. Logarithmic growth was maintained for the 48-h measurement period, using a
light flux of 6,000 lux. The pH and aluminium concentrations were again measured
at the end of each experiment.
Reference substance (positive control):
no
Duration:
48 h
Dose descriptor:
EC50
Effect conc.:
22.3 mg/L
Nominal / measured:
meas. (geom. mean)
Conc. based on:
dissolved
Remarks:
Aluminium
Basis for effect:
growth rate
Remarks on result:
other: at pH 5.2 and pH 6.7
Duration:
48 h
Dose descriptor:
EC50
Effect conc.:
14 µg/L
Nominal / measured:
meas. (geom. mean)
Conc. based on:
dissolved
Remarks:
Aluminium
Basis for effect:
growth rate
Remarks on result:
other: pH 5.6 and pH 6.4

Equilibrium constant calculations (13) showed that sulphato, bicarbonato, and chloro complexes of aluminiool were insignificant in the solutions studied. Algal growth rate measurements in aluminium solutions of pH 5.8 to 6.2, where the concentration of the polymer was at a maximum, showed that toxicity was a function of labile, rather than total, alnminium. This result indicates that the polymer itself is non-toxic. the labile aluminium concentration (Al tox ) required to cause a 50% reduction in algal growth rate is plotted against pH. Experiments with aluminium-free solutions demonstrated that pH in the range 4.9 to 7.1 has little effect on algal growth. Also included are computer-generated plots of Al tox versus pH. where it is assumed that the toxic species is either Al(OH)2+ or the sum of Al(OH)2+, Al(OH)2+ and Al(OH)3. By comparing the toxicity-pH curve with the distribution data, it is seen that the labile species Al3+, Al(OH)3 and AI(OH)4- do not contribute significantly to the toxicity of aluminium towards Chlorella pyrenoidosa; the toxic species must be Al(OH)2+ or a combination of Al(OH)2+ and Al(OH)2+. The computer-generated toxicity functions show better agreement with the experimental curve when Al(OH)2+ is assumed to be the sole toxic species.

The results of this study indicate that dissolved aluminium would be highly toxic to algae, and perhaps to other aquatic organisms, in natural fresh waters which are slightly acidic and low in organic matter and nutrients such as phosphate and silicate.

Ligand

Concentration mg/L

Labile Aluminium ug/L

Growth rate as % of blank

None

0

2.05

48

Salicylic acid

5.0

24.8

85

Fulvic acid

10.0

17.0

85

Tannic acid

4.0

<2

113

PO43-

10.0

10.1

125

F-

1.00

8.5

62

SO42-

1.000

22.3

50

SiO32-

6.0

<5

116

Validity criteria fulfilled:
not applicable
Conclusions:
The EC50 of Aluminium to algae varies with pH, most appropriate (due to pH and available species) was 22.4 ug/L. Study is mostly valid although no valid method used it seems to be scientific sound. Information on substance identity is missing and the study has not been performed under GLP. It is therefore that the reliabiliity is rated as Klimish 4.
Executive summary:

A new algal assay technique was used to determine the effect of the chemical form of aluminium on toxicity in a synthetic hard water. Maximum toxicity occurred at pH 5.8 to 6.2, where as little as 5 µg/L of labile aluminium significantly inhibited algal growth. The EC50 was determined to be 22.4 mg/L at pH 5.2 and 6.8. Algal assay and computer modelling results implicate Al(OH)2+ as the aluminium species most toxic to algae.

Endpoint:
toxicity to aquatic algae and cyanobacteria
Type of information:
migrated information: read-across based on grouping of substances (category approach)
Adequacy of study:
supporting study
Study period:
1993
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: see 'Remark'
Remarks:
Very detailed article, non GLP, complete however applicability of endpoints in riskassessment might be restricted due to no complete substance identity data and the fact that only EC30 values are presented in the article, the reviewer has himself determniend EC10 values. Therefore it is reliable with restrictions
Guideline:
other: Rogeberg, E.J.S. and A. Henriksen. 1985. An automated method for fractionation and determination of aluminum species in fresh-waters. Vatten 41:48-53.
Guideline:
other: Allison, J.D., D.S. Brown and K.J. Novo-Gradac. 1991. MINTEQA2/PRODEFA2, User's Manual, Version 3.0. EPA 600/3-91-021. U.S. Environmental Protection Agency, Washington, DC.
Guideline:
other: Wehr, J.D., L.M. Brown and I.E. Vanderelst. 1986. Hydrogen ion buffering of culture media for algae from moderately acidic, oligotrophic waters. J. Phycol. 22:88-94.
Guideline:
other: Stainton, M.P., M.J. Capel and F.A.J. Armstrong. 1974. The chemical analysis of fresh water. Miscellaneous Special Publication 25. Canadian Department of Environment, Ottawa. Ontario.
Principles of method if other than guideline:
analyses was performed according to Rogeberg and Henriksen 1985
GLP compliance:
not specified
Analytical monitoring:
yes
Details on sampling:
Al speciation Concentrations of total, dissolved, and monomeric Al
were determined daily in the exposure media. The Al speciation
measurements involved an initial filtration step (0.4 um
Nuclepore® polycarbonate filters; Nuclepore Corp., Pleasanton,
CA) to distinguish operationally between particulate and
dissolved AI. Aliquots of both the original sample and the
filtrate were acidified (2 uI HN03 per ml; Ultrex grade, J.T.
Baker Chem. Co., Phillipsburg, NJ),
Vehicle:
no
Details on test solutions:
The Al was added as a concentrated
solution of AICI3 (3.7.10-4 M, pH <2; prepared by dilution
of an AA standard, Fisher Scientific, Montreal, QC)
and allowed to equilibrate in the exposure media for 24 h.
Two buffers were used for pH control: 2-(N-morpholino)ethanesulfonic
acid (MES; pH 5.0, 5.5, and 6.0); 3,3-dimethylglutaric
acid (DMGA; pH 4.3 and 4.6); in both cases
buffer concentrations of 0.01 M were needed to maintain a
reasonably constant pH over the growth period. In choosing
the maximum Al concentrations for these experiments,
we took particular care to avoid the formation of hydroxyAl
colloids or polynuclear species (i.e., initial concentrations
of inorganic Al were chosen to lie below the solubility limit
for microcrystalline gibbsite, AI(OHh(s)).
Test organisms (species):
Chlorella pyrenoidosa
Details on test organisms:
Stock cultures of C. pyrenoidosa (University of Toronto
Culture Collection UTCC 89) were maintained in a semicontinuous
culture system under controlled and constant
temperature (22°C) and light conditions (115 JLE m-2 S-I).
Stock cultures were grown in algal assay procedure (AAP)
growth medium, as modified by Chiaudani and Vighi [8],
under constant bubbling with filtered air in Teflon® containers
(1-2 L). Cell densities in these cultures were monitored
daily with an electronic particle counter (Coulter Electronics,
Toronto, Ontario; model TA-II, 70-JLm orifice). The particle
counter was calibrated with C. pyrenoidosa suspensions
for which the cell dimenSIons had been measured by optical
micrometry. Cultures were diluted to maintain a cell concentration
of approximately 105 cells ml-1
, which corresponded
to the early exponential growth phase. Axenicity of the stock
culture was monitored regularly by plating the culture onto
BHI nutrient broth 1/10 (Difco, Detroit, MI).
Test type:
static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
96 h
pH:
4.3-6.0
Nominal and measured concentrations:
nominal: 25, 50, 100, 150 ug/L
Details on test conditions:
Although the test algae were maintained in complete AAP
growth medium, the subsequent bioassays were carried out
in solutions based on the AAP medium but contained no
added trace metals, EDTA, or phosphorus (referred to as
AAP-). By simplifying the exposure medium in this manner,
we sought to avoid possible experimental artifacts attributable
to AI-P interactions in solution [6], or to competition
between Al and other trace metals at the algal surface [9].
Bioassays designed to test the effects of mononuclear
inorganic Al were performed at nominal pH values of 4.3,
4.6,5.0,5.5, and 6.0.
Reference substance (positive control):
no
Duration:
96 h
Dose descriptor:
other: EC30
Effect conc.:
70 other: nmol/L
Nominal / measured:
meas. (initial)
Conc. based on:
dissolved
Remarks:
monomeric Al3+
Basis for effect:
growth rate
Remarks:
pH 6
Duration:
96 h
Dose descriptor:
EC50
Effect conc.:
172.8 µg/L
Nominal / measured:
nominal
Conc. based on:
dissolved
Remarks:
monomeric Al3+
Basis for effect:
growth rate
Remarks:
determined by reviewer at pH 5
Duration:
96 h
Dose descriptor:
EC10
Effect conc.:
84 µg/L
Nominal / measured:
nominal
Conc. based on:
dissolved
Remarks:
monomeric Al3+
Basis for effect:
growth rate
Remarks:
determined by reviewer at pH5
Duration:
96 h
Dose descriptor:
other: EC30
Effect conc.:
1.8 µmol/L
Nominal / measured:
meas. (not specified)
Conc. based on:
dissolved
Remarks:
monomeric Al3+
Basis for effect:
growth rate
Remarks:
pH 5
Details on results:
The sensitivity of algal growth to inorganic monomeric
Al (Al-mono) was determined over the pH range 4.3 to 6.0
in buffered media. Inhibition of algal growth by
Almono was slight at pH 4.3 or 4.6 but increased markedly
at pH >=5. Plots of area under
the growth curve as a function of [Al]mono showed the
expected concentration dependence. EC30 values extracted
from such plots, expressed in terms of the free AI3+
ion, showed a marked pH dependence
Reported statistics and error estimates:
The effects of Al on algal growth were determined by comparing
the areas under the growth curves for the various
cultures (cell numbers vs. time over 4 d; cf. Nyholm [11]),
and EC30 values were determined for different pH values
(EC30 = the concentration of inorganic monomeric Al that inhibited
algal growth by 30070 compared to an AI-free control).
In one series of experiments designed to explore links between
Al toxicity and phosphate metabolism, particulate
phosphorus was determined on day 4 of the Al exposure,
according to the automated ascorbic acid/molybdenum blue
method described by Stainton et al. 1974. The EC10 and EC50 were determniend by lineair regression by the reviewer based on nominal contrations, available in the article. These values are, 84 and 172.8 ug/L respectively
Validity criteria fulfilled:
not applicable
Conclusions:
The EC30 was determined by the authors to be 70 nmol/L (at pH 6) and 1.8 umol/L at pH 5 (measured concentrations). The EC10 and EC50 (at pH 5) were determined by lineair regression by the reviewer based on nominal contrations, available in the article. These values are, 84 and 172.8 ug/L respectively. Study is valied and scientific sound but not performed under GLP.
Executive summary:

A unicellular green alga, Chlorella pyrenoidosa, was exposed to inorganic Al under controlled experimental conditions to determine whether the biological response elicited by the dissolved metal could be predicted from the free-metal ion concentration, [AI3+]. The experimental approach involved concurrent measurement of both AI speciation and AI bioavailability (bioaccumulation/growth inhibition) in buffered synthetic solutions of defined composition. The bioassay exposure media, containing neither phosphate nor trace metals, covered the pH range 4.3 to 6. For systems at a given pH, containing only inorganic monomeric AI, aluminum bioavailability varies predictably as a function of the free AP+ concentration. However, the effect of A13+ on algal growth is highly pH dependent; [AJ3+] needed to inhibit growth by 30010 (EC30) increases markedly from

3 ug/L (0.1 uM) to 50 ug/L (1.8 uM) as the pH is decreased from 6 to 5. This decreased toxicity of AI at low pH is partly explained by an effective competition between the H+ ion and Al3+ for binding sites at the algal surface; the effects of acidification at the biological surface are much more important than are its. effects on Al speciation in solution.

For systems containing both monomeric and polynuclear Al (the AI04AJdOH);r polycation), polymeric aluminum also contributes to aluminum toxicity. The EC10 and EC50 (at pH 5) were determined by lineair regression by the reviewer based on nominal contrations, available in the article. These values are, 84 and 172.8 ug/L respectively.

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
Study period:
14 June 2010 - 29 July 2010
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: This study has been performed according to OECD and/or EC guidelines and according to GLP principles.
Qualifier:
according to guideline
Guideline:
OECD Guideline 201 (Alga, Growth Inhibition Test)
Deviations:
no
Qualifier:
according to guideline
Guideline:
EU Method C.3 (Algal Inhibition test)
Deviations:
no
Qualifier:
according to guideline
Guideline:
ISO 8692 (Water Quality - Fresh Water Algal Growth Inhibition Test with Scenedesmus subspicatus and Selenastrum capricornutum)
Deviations:
no
GLP compliance:
yes
Analytical monitoring:
yes
Details on sampling:
Samples for possible analysis were taken from all test concentrations and the control according to the schedule below.
Frequency at t=0 h, t=24 h and t=72 h
Volume 4.8 ml
Storage Samples were stored in a freezer until analysis.

At the end of the exposure period, the replicates with algae were not pooled at each concentration before sampling. Samples were taken from only one replicate vessel per concentration, unless differences in cell density between replicate vessels were observed.
Compliance with the Quality criteria regarding maintenance of actual concentrations was demonstrated by running a test vessel at the highest substance concentration but without algae and samples for analysis were taken at the start, after 24 hours of exposure and at the end of the test period.
Additionally, reserve samples of 4.8 ml were taken from all test solutions for possible analysis. If not already used, these samples were stored in a freezer for a maximum of three months after delivery of the draft report, pending on the decision of the sponsor for additional analysis.
Vehicle:
no
Details on test solutions:
The batch of 202028/A tested was a clear colourless liquid with an aluminium content of 4.4%. The substance was completely soluble in test medium at the concentrations tested.

Preparation of test solutions started with a loading rate of 100 mg/l applying 15 minutes of magnetic stirring to accelerate the dissolving of the test substance in the test medium. The lower test concentrations were prepared by subsequent dilutions of the 100 mg/l concentration in test medium. The final test solutions were all clear and colourless.

After preparation, volumes of 50 ml were added to each replicate of the respective test concentration. Subsequently, 1 ml of an algal suspension was added to each replicate providing a cell density of 1000 cells/ml.
Test organisms (species):
Pseudokirchneriella subcapitata (previous names: Raphidocelis subcapitata, Selenastrum capricornutum)
Details on test organisms:
TEST ORGANISM
- Common name: Pseudokirchneriella subcapitata
- Strain: NIVA CHL 1.
- Source (laboratory, culture collection): In-house laboratory culture
- Age of inoculum (at test initiation): 3 days before the start of the test, cells from the algal stock culture were inoculated in culture medium at a cell density of 1 x 10E4 cells/ml.
- Method of cultivation: Algae stock cultures were started by inoculating growth medium with algal cells from a pure culture on agar. The suspensions were continuously aerated and exposed to light (60 to 120 µE/m2/s when measured in the photosynthetically effective wavelength range of 400 to 700 nm. in a climate room at a temperature of 21-24°C.
Test type:
static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
72 h
Hardness:
0.24 mmol(24 mg CaCO3/L)
Test temperature:
between 22.1 and 23.4°C
pH:
between 7.1 and 8.4
Nominal and measured concentrations:
Nominal concentrations: control and 1.0, 3.2, 10, 32 and 100 mg/l
Measured concentrations: The initial concentrations of aluminium were generally in agreement with nominal (72-100%). These concentrations significantly decreased during the test period. This decrease could be related to the fact that part of the test substance came out of the solution during the exposure period, as was observed before during the combined limit/range-finding test. From 24 hours of exposure onwards undissolved material was observed in all test concentrations. At nominal 3.2 mg/l the presence of undissolved material caused an anomaly in the measured concentrations.
Based on these results, the effect parameters were expressed in terms of both the nominal concentrations of PAX-XL9 and the average dissolved aluminium concentrations that were calculated to be 0.02, 0.04, 0.23, 0.47 and 2.8 mg/l.
Details on test conditions:
TEST SYSTEM
- Type: open
- Material, size, headspace, fill volume: 100 ml, normal headspace, 50 ml
- Aeration: no
- Initial cells density: 10000 cells/ml
- Control end cells density: 1600000 cells/ml
Replicates:
3 replicates of each test concentration;
6 replicates of the control;
1 extra replicate of each test concentration and the control for sampling purposes;
1 or 2 extra replicates of each test concentration without algae.

GROWTH MEDIUM
- Standard medium used: yes
OTHER TEST CONDITIONS
- Sterile test conditions: no
- Adjustment of pH: no
- Photoperiod: continuous
- Light intensity and quality: Continuously using TLD-lamps of the type ‘Cool-white’ of 30 Watt, with a light intensity within the range of 81 to 89 µE.m-2.s-1

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
72 h NOErC, 72 h NOEyC, 72 h ErC10, 72 h EyC10 ,72 h ErC50, 72 h EyC50

TEST CONCENTRATIONS
- Spacing factor for test concentrations: 3.2
- Test concentrations: control and 1.0, 3.2, 10, 32 and 100 mg/l
Reference substance (positive control):
yes
Remarks:
potassium dichromate (K2Cr2O7,)
Duration:
72 h
Dose descriptor:
NOEC
Effect conc.:
1 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth rate
Duration:
72 h
Dose descriptor:
EC10
Effect conc.:
3.1 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth rate
Remarks on result:
other: 95% CI:0.36-8.4 mg/l
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
14 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth rate
Remarks on result:
other: 95% CI:6.8-24 mg/l
Duration:
72 h
Dose descriptor:
NOEC
Effect conc.:
< 1 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
other: Yield
Duration:
72 h
Dose descriptor:
EC10
Effect conc.:
0.88 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
other: Yield
Remarks on result:
other: 95% CI: 0.52-1.5 mg/l
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
4.4 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
other: Yield
Remarks on result:
other: 95% CI: 2.7-7.1 mg/l
Duration:
72 h
Dose descriptor:
NOEC
Effect conc.:
0.02 mg/L
Nominal / measured:
meas. (TWA)
Conc. based on:
element
Remarks:
Aluminium
Basis for effect:
growth rate
Duration:
72 h
Dose descriptor:
EC10
Effect conc.:
0.051 mg/L
Nominal / measured:
meas. (TWA)
Conc. based on:
element
Remarks:
Aluminium
Basis for effect:
growth rate
Remarks on result:
other: 95% CI:0.001-0.23 mg/l
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
0.24 mg/L
Nominal / measured:
meas. (TWA)
Conc. based on:
element
Remarks:
Aluminium
Basis for effect:
growth rate
Remarks on result:
other: 95% CI: 0.058-0.54 mg/l
Duration:
72 h
Dose descriptor:
NOEC
Effect conc.:
< 0.02 mg/L
Nominal / measured:
meas. (TWA)
Conc. based on:
element
Remarks:
Aluminium
Basis for effect:
other: Yield
Duration:
72 h
Dose descriptor:
EC10
Effect conc.:
0.015 mg/L
Nominal / measured:
meas. (TWA)
Conc. based on:
element
Remarks:
aluminium
Basis for effect:
other: Yield
Remarks on result:
other: 95% CI: 0.007-0.031 mg/l
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
0.075 mg/L
Nominal / measured:
meas. (TWA)
Conc. based on:
element
Remarks:
aluminium
Basis for effect:
other: Yield
Remarks on result:
other: 95% CI: 0.039-0.14 mg/l
Details on results:
Microscopic observations at the end of the test revealed a normal and healthy appearance of the exposed cells when compared to the control.
Results with reference substance (positive control):
Potassium dichromate reduced growth rate of this fresh water algae species at nominal concentrations of 0.56 mg/l and higher.
The EC50 for growth rate reduction (ERC50: 0-72h) was 1.1 mg/l with a 95% confidence interval ranging from 1.0 to 1.3 mg/l.
The EC50 for yield inhibition (EYC50: 0-72h) was 0.59 mg/l with a 95% confidence interval ranging from 0.51 to 0.68 mg/l.
Reported statistics and error estimates:
For determination of the NOEC and the EC50 the approaches recommended in the OECD guideline 201 were used. An effect was considered to be significant if statistical analysis of the data obtained for the test concentrations compared with those obtained in the negative control revealed significant reduction of growth rate or inhibition of yield (ANOVA, Tukey test, Bonferroni t-test, TOXSTAT Release 3.5, 1996, D.D. Gulley, A.M. Boelter, H.L. Bergman). Additionally, the EC10 was determined to meet the recommendations as put down in "A Review of Statistical Data Analysis and Experimental Design in OECD Aquatic Toxicology Test Guidelines" by S. Pack, August 1993. Calculation of the EC50 and EC10 values was based on log-linear regression analysis of the percentages of growth rate reduction and the percentages of yield inhibition versus the square root (growth rate) or the logarithms (yield) of the corresponding concentrations of the test substance.
Statistically significant reduction of growth rate was found at nominal test concentrations of 3.2 mg/l and higher (Bonferroni t and Tukey test, α = 0.05).
Statistically significant inhibition of yield was found at all nominal concentrations tested (Bonferroni t and Tukey test, α = 0.05).
Validity criteria fulfilled:
yes
Conclusions:
The EC50 for growth rate reduction (ERC50: 0-72h) was 14 mg/l based on nominal concentrations of 202028/A. The average concentration of dissolved aluminium originating from 202028/A was 0.24 mg/l. The NOEC for growth rate reduction was nominally 1.0 mg/l (0.02 mg/l when based on aluminium). The EC50 for yield inhibition (EYC50: 0-72h) was 4.4 mg/l based on nominal concentrations of PAX-XL9. The average concentration of dissolved aluminium originating from PAX-XL9 was 0.075 mg/l.
The NOEC for yield inhibition was nominally <1.0 mg/l (<0.02 mg/l when based on aluminium).
Executive summary:

This 72h-static test was performed on Pseudokirneriella subcapitata, to evaluate the toxicity of Aluminium chloride hydroxide sulphate. The EC50 for growth rate reduction (ERC50: 0-72h) was 14 mg/L based on nominal concentrations of 202028/A. The average concentration of dissolved aluminium originating from 202028/A was 0.24 mg/L. The NOEC for growth rate reduction was nominally 1.0 mg/L (0.02 mg/L when based on aluminium). The EC50 for yield inhibition (EYC50: 0-72h) was 4.4 mg/L based on nominal concentrations of PAX-XL9. The average concentration of dissolved aluminium originating from PAX-XL9 was 0.075 mg/L. The NOEC for yield inhibition was nominally <1.0 mg/L (<0.02 mg/L when based on aluminium).

Description of key information

OECD guideline 201, EU method C.3, ISO 8692, GLP, key study, validity 1 (Bouwman, 2010):

72h-EC50 (growth rate) = 14 mg/L (based on nominal concentrations, 95 % CI = 6.8 - 24 mg/L)

72h-EC50 (growth rate) = 0.24 mg/L (95 % CI = 0.058 - 054 mg/L, based on the aluminium element concentrations)

Key value for chemical safety assessment

EC50 for freshwater algae:
14 mg/L
EC10 or NOEC for freshwater algae:
3.1 mg/L

Additional information

There is no available data on the registered substance for toxicity to aquatic algae.

Four read-across studies are available : one key study on aluminium chloride hydroxide sulphate, one supporting study on aluminium sulphate, one disregarded study on aluminium sulphate and one last supporting study on an unknown substance (inorganic Al).

1) This 72h-static test was perofrmed on Pseudokirneriella subcapitata, to evaluate the toxicity of Aluminium chloride hydroxide sulphate. The EC50 for growth rate reduction (ERC50: 0-72h) was 14 mg/l based on nominal concentrations of 202028/A. The average concentration of dissolved aluminium originating from 202028/A was 0.24 mg/l. The NOEC for growth rate reduction was nominally 1.0 mg/l (0.02 mg/l when based on aluminium). The EC50 for yield inhibition (EYC50: 0-72h) was 4.4 mg/l based on nominal concentrations of PAX-XL9. The average concentration of dissolved aluminium originating from PAX-XL9 was 0.075 mg/l. The NOEC for yield inhibition was nominally <1.0 mg/l (<0.02 mg/l when based on aluminium).

2) A new algal assay technique was used to determine the effect of the chemical form of aluminium on toxicity in a synthetic hard water on Chlorella pyrenoidosa. This static test ran for 11 days. Maximum toxicity occurred at pH 5.8 to 6.2, where as little as 5 µg/L of labile aluminium significantly inhibited algal growth. The EC50 was determined to be 22.4 mg/L at pH 5.2 and 6.8. Algal assay and computer modelling results implicate Al(OH)2+ as the aluminium species most toxic to algae.

Information on substance identity is missing and the study has not been performed under GLP. It is therefore that the reliabiliity is rated as Klimisch 4.

3) This 26 days-static test was performed on Chlorella pyrenoidosa to evaluate the toxicity of Aluminium sulphate.
Chlorella pyrenoidosa , a green algae which has no measurable Ca requirement, tolerated much higher Al concentrations in solution than higher plants which require considerable Ca. This algae also gave significant positive yield respons to al concentrations between 1.5 and 12 ppm (added at pH 4.6) the positive Al respons was not attributed to V, Gr, Ni, Co, W orTi contaminants in the salt.

The EC50 was determined to be 5.8 ppm. But the study is not considered reliable as too much data is missing.

4) A unicellular green alga, Chlorella pyrenoidosa, was exposed to inorganic Al under controlled experimental conditions to determine whether the biological response elicited by the dissolved metal could be predicted from the free-metal ion concentration, [AI3+]. The experimental approach involved concurrent measurement of both AI speciation and AI bioavailability (bioaccumulation/growth inhibition) in buffered synthetic solutions of defined composition. The bioassay exposure media, containing neither phosphate nor trace metals, covered the pH range 4.3 to 6. For systems at a given pH, containing only inorganic monomeric AI, aluminum bioavailability varies predictably as a function of the free AP+ concentration. However, the effect of A13+ on algal growth is highly pH dependent; [AJ3+] needed to inhibit growth by 30010 (EC30) increases markedly from

3 ug/L (0.1 uM) to 50 ug/L (1.8 uM) as the pH is decreased from 6 to 5. This decreased toxicity of AI at low pH is partly explained by an effective competition between the H+ ion and Al3+ for binding sites at the algal surface; the effects of acidification at the biological surface are much more important than are its. effects on Al speciation in solution.

For systems containing both monomeric and polynuclear Al (the AI04AJdOH);r polycation), polymeric aluminum also contributes to aluminum toxicity. The EC10 and EC50 (at pH 5) were determined by lineair regression by the reviewer based on nominal contrations, available in the article. These values are, 84 and 172.8 ug/L respectively.