Aluminium tri-sec-butanolate

Toxicity to aquatic algae and cyanobacteria

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

toxicity to aquatic algae and cyanobacteria

Type of information:

experimental study

Adequacy of study:

weight of evidence

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

test procedure in accordance with national standard methods with acceptable restrictions

Qualifier:

equivalent or similar to guideline

Guideline:

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

GLP compliance:

not specified

Remarks:

Information on GLP is not reported. Quality of the report implies that GLP conditions were met.

Specific details on test material used for the study:

AlCl3x6H2O, Ajax Finechem, Univar, AR grade)

Analytical monitoring:

yes

Vehicle:

yes

Remarks:

seawater

Details on test solutions:

Bioassay test solutions werde prepared in triplicate using filtered seawater with nutrients added and incubated for 72h at 21°C in 12:12 h light/dark cycle.Cells were harvested from cultures in their exp growth phase (5-6d) and rinsed 3 times in seawter using centrifugation to remove residual culture media. Initial algal coonc were 2x10exp4 cells/mL to 4x10exp4 cells/mL for C. closterium and 2x10exp3 to 4x10exp3 cells/mL for the other species. Flasks were shaken manually twice a day and positioned randomly to account for light and temperature gradients. The algal conc was measured daily using flow cytometry. Growth rate was calculated as the slope of the linear regression of log10 algal cell conc vs time and was used in deriving the chronic effect value for algal growth inhibition. The test was acceptable if the control growth rate was >1 doubling/d and the control growth rate coeefeicient of variation was <10%, and the inhib conc, 50% (IC50) for the copper reference test was within 2SD of the mean.

Test organisms (species):

other: Ceratoneis closterium (formerly Nitzschia closterium), Minutocellus polymorphus, Dunaliella tertiolecta, Tetraselmis sp.

Details on test organisms:

The C. closterium cells were gently homogenized to reduce clumping of cells priot to counting. Inspection of cells under the microscope before and after homogenizing confirmed no damage to cells and reduced clumping. Homogenization was not needed for the other species.

Test type:

static

Water media type:

saltwater

Total exposure duration:

72 h

Test temperature:

21°C

pH:

8.2

Dissolved oxygen:

100 % saturation (±4% SD)

Nominal and measured concentrations:

10-100000µg Al/L nominal

Reference substance (positive control):

yes

Remarks:

CuSO4x5H2O

Duration:

72 h

Dose descriptor:

IC10

Effect conc.:

1 400 µg/L

Nominal / measured:

meas. (initial)

Conc. based on:

element (total fraction)

Basis for effect:

growth rate

Remarks on result:

other: Dunaliella tertiolecta

Duration:

72 h

Dose descriptor:

IC50

Effect conc.:

1 100 µg/L

Nominal / measured:

meas. (initial)

Conc. based on:

element (dissolved fraction)

Basis for effect:

growth rate

Remarks on result:

other: Dunaliella tertiolecta

Duration:

72 h

Dose descriptor:

IC10

Effect conc.:

18 µg/L

Nominal / measured:

meas. (initial)

Conc. based on:

element (total fraction)

Basis for effect:

growth rate

Remarks on result:

other: Ceratoneis closterium

Duration:

72 h

Dose descriptor:

IC10

Effect conc.:

690 µg/L

Nominal / measured:

meas. (initial)

Conc. based on:

element (total fraction)

Basis for effect:

growth rate

Remarks on result:

other: Minutocellus polymorphus

Duration:

72 h

Dose descriptor:

IC10

Effect conc.:

3 200 µg/L

Nominal / measured:

meas. (initial)

Conc. based on:

element (total fraction)

Basis for effect:

growth rate

Remarks on result:

other: Tetraselmis sp.

Duration:

72 h

Dose descriptor:

IC10

Effect conc.:

1 300 µg/L

Nominal / measured:

meas. (initial)

Conc. based on:

element (dissolved fraction)

Basis for effect:

growth rate

Remarks on result:

other: Tetraselmis sp.

Details on results:

The toxicity of Al to the chronic growth rate of marine microalgae as quantified by the IC10 was species specific, with greater effects on diatoms relative to green algae. The microalgal species ranked in sensitivity to Al as follows: C. closterium ) > M. polymorphus > D. teriolecta > Tetraselmis sp.
Toxicity appears to be more strongly related to dossolved Al with potential contributions from particulate Al at total concentations of <100µg/L.
For D tertiolecta, there was a sharp drop in algal growth tae above 890 µg total Al/L. Growth rate reached 50% of the control where dissolved Al reached a max of 1700 µg/L and total Al conc exceeded 4000 µg/L. This region of the the concentration-response curve was dominated by particulate Al and there was little change in dssolved Al conc with increasing total Al concentration. Growth rate eclined further to 30% of control when total Al reached 43000 µg/L. Growth rates showed the best relationship with total Al, suggesting that a combination or particulate and dissolved forms contribute to toxicity.

Reported statistics and error estimates:

Concnentration-response curves were constructed using the biological effect as a funtion of the measure Al conc data from the bioassay. The IC50 for each organisms was determined by nonlinear regression using R package drc (2.3-0). The package uses log-logistic and Weibull models. The 95% confidence limits on the toxicity values were genrated using the delta method of estimating the asmptotic standard error and the approp t-distribution.

Conclusions:

In the present study, IC10 and IC50 for Dunaliella tertiolecta are 1400 and 4200 µg Al/L for total Al concentration. For dissolved Al conc, IC10 and IC50 for Dunaliella tertiolecta are 960 and 1100 µg Al/L. The studies showed that dissolved forms of Al dominate below approx 500 µg/L.. Above 1000 µg/L particulate Al hydroxide becomes increasingly dominant. Thus, the authors conclude that Dunaliella tertiolecta was affected by a combination of dissolved and particulate Al species.
In conclusion, the derived IC values are above the water solubility of the relevant Al species in the frame of the experimental conditions.

Reference 2

Endpoint:

toxicity to aquatic algae and cyanobacteria

Type of information:

experimental study

Adequacy of study:

weight of evidence

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

comparable to guideline study with acceptable restrictions

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 201 (Alga, Growth Inhibition Test)

GLP compliance:

no

Specific details on test material used for the study:

no data

Analytical monitoring:

no

Vehicle:

yes

Details on test solutions:

diluted in distilled water

Test organisms (species):

Stichococcus sp.

Details on test organisms:

TEST ORGANISM: Monoraphidium Monoraphidium dybowskii and Stichococcus sp.
- Source: from slightly acidified Swedish lakes
- Age of inoculum (at test initiation):
- Method of cultivation: grown in erlenmeyer flasks (at 25 °C and continuous light 100 uE/m2s), reinoculated once weekly --> exponentially growing

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

10 d

Remarks on exposure duration:

10-12 days

pH:

tests at pH 5.0, 5.5 and 6.0

Nominal and measured concentrations:

0, 0.10, 0.18, 0.32, 0.56, 1.00 and 1.80 mg/L as Al,

Details on test conditions:

TEST SYSTEM
- Test vessel: Erlenmeyer flask
- Aeration: no data
- Initial cells density: 10E7 cells/L
- Control end cells density: ca 10E9 (taken from figure in the publication)
- No. of vessels per concentration (replicates): 3
- No. of vessels per control (replicates): 3

GROWTH MEDIUM
- Standard medium used: no data

TEST MEDIUM / WATER PARAMETERS: similar to growth medium

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
- Determination of cell concentrations: particle counter (Coulter counter)
- Other: cell size of living cells

Duration:

12 d

Dose descriptor:

EC50

Effect conc.:

1.1 mg/L

Nominal / measured:

nominal

Conc. based on:

element

Basis for effect:

growth rate

Remarks on result:

other: for Monoraphidium dybowskii

Duration:

10 d

Dose descriptor:

EC50

Effect conc.:

0.54 mg/L

Nominal / measured:

nominal

Conc. based on:

element

Basis for effect:

growth rate

Remarks on result:

other: for Stichococcus sp

Duration:

12 d

Dose descriptor:

NOEC

Effect conc.:

0.04 mg/L

Nominal / measured:

nominal

Conc. based on:

element

Basis for effect:

growth rate

Remarks on result:

other: for Monoraphidium dybowskii

Duration:

10 d

Dose descriptor:

NOEC

Effect conc.:

0.23 mg/L

Nominal / measured:

nominal

Conc. based on:

element

Basis for effect:

growth rate

Remarks on result:

other: for Stichococcus sp

Duration:

12 d

Dose descriptor:

NOEC

Effect conc.:

0.1 mg/L

Nominal / measured:

nominal

Conc. based on:

element

Basis for effect:

other: cell decomposition

Remarks on result:

other: for both algae species

Conclusions:

The EC50 for growth rate in both algae species tested is 0.54-1.1 mg/L
The NOEC is 0.04-0.23 mg/L

Reference 3

Endpoint:

toxicity to aquatic algae and cyanobacteria

Type of information:

experimental study

Adequacy of study:

weight of evidence

Study period:

1976

Reliability:

3 (not reliable)

Rationale for reliability incl. deficiencies:

other: Not GLP, not guideline compliant. Growth expressed as relative turbidity was determined only at the beginning and the end of the study (8 d). Oxygen concentration not measured. Procedure in accordance with generally accepted standards.

Qualifier:

no guideline followed

Principles of method if other than guideline:

Inhibition of cell proliferation following addition of the test substance to cultures of Scenedesmus quadricauda. Growth was measured as relative turbidity at the beginning and at the end of the study. Method is sufficiently described in the article.

GLP compliance:

no

Specific details on test material used for the study:

Details on properties of test surrogate or analogue material:
Aluminium tri-sec-butylate reacts instantaneously with water to form 2-butanol and Al3+ species. The resulting pH being weakly alkaline indicates according to Langmuir et al. 2004 that Al3+ species formed are mainly Al(OH)4-, Al(OH)3 and Al(OH)2+ at pH 8.5.
Thus, aluminium tri-sec-butylate is abiotically degradable and forms 2-butanol being readily biodegradable as shown in the registration dossier of 2-butanol submitted by the same lead registrant. Thus, 2-butanol is the ideal surrogate for testing toxicity effects on aquatic plants such as green algae posed by the organic moiety of the reference substance.

Analytical monitoring:

no

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION
- Method: TS was dissolved in sterile ddH2O. Whenever necessary, pH was adjusted to 7.0.
- Initial concentration: not specified

Test organisms (species):

Scenedesmus quadricauda

Details on test organisms:

TEST ORGANISM
- Common name: green algae
- Source: laboratory collection
- Age of inoculum (at test initiation): 10 d
- Method of cultivation: cultures were grown in 100 mL Erlenmeyer flasks containing 20 mL medium at 27 °C. Cultures were refreshed (2 mL inoculum) every 10 days.

ACCLIMATION
- Acclimation period: 10 d
- Culturing media and conditions: same as test

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

8 d

Post exposure observation period:

none

Test temperature:

27 °C

pH:

7

Nominal and measured concentrations:

1 part TS solution (concentration not specified) in 2 E0 - 2 E14 parts mixture (i.e. 1:1, 1:2, 1:4, 1:8... 1:16384) (nominal)

Details on test conditions:

TEST SYSTEM
- Test vessel: Kapsenberg culture tubes covered with metal caps
- Type: open
- Material: glass; size: 18X180 mm; fill volume: 10 mL
- Aeration: none. Cultures were shaken once a day
- Initial cells density: relative turbidity (formazin turbidity equivalents TE/F/578 nm) = 20
- No. of vessels per concentration: 3
- No. of vessels per control: 3

GROWTH MEDIUM
- Standard medium used: no
- Detailed composition if non-standard medium was used:
Stammlösung 1
248 mg NaNO3
19.5 mg K2HPO4
750 mg MgSO4*7(H2O)
360 mg CaCl2*2(H2O)
30 mg Citric acid, C6H8O7*H2O
30 mg Iron-(III)-citrate, C6H5FeO8*5(H2O)
100 mg Disodium edetate dihydrate
dissolved in ddH2O, then were added 10 mL of the diluted Stammlösung 2. The medium was then brought to 1 L ddH2O, pH 7.0.

Stammlösung 2
2.86 g Boric acid
1.81 g MnCl2*4(H2O)
220 mg ZnSO4*7(H2O)
80 mg CuSO4*5(H2O)
24 mg Na2MoO4*2(H2O)
40 mg CoCl2*6(H2O)
dissolved in ddH2O. Final volume 1 L.

Diluted Stammlösung 2: 4 mL of the Stammlösung 2 in 100 mL ddH2O

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: double distilled
- Culture medium different from test medium: yes

OTHER TEST CONDITIONS
- Sterile test conditions: yes
- Adjustment of pH: none
- Photoperiod: continuous artificial light

EFFECT PARAMETERS MEASURED:
- Determination of cell turbidity: spectrophotometer

TEST CONCENTRATIONS
- Spacing factor for test concentrations: 2

Duration:

8 d

Dose descriptor:

other: TGK (Toxische Grenzkonzentration or "toxicity threshold concentration")

Effect conc.:

95 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

other: growth inhibition

Note on the results

In the paper, the TGK value for S. quadricauda relative to 2-butanol appears to be mistakenly attributed to n-butanol, which was instead reported twice in the same table.

In the study, the TGKs for Pseudomonas putida relative to 2-butanol and n-butanol are respectively: 500 mg/L and 650 mg/L (table 1 in the article). The TGKs for S. quadricauda relative to n-butanol are: 95 mg/L and 875 mg/L (table 2 in the article). The approximated ratio of TGK(S. quadricauda) versus TGK(P. putida) for 2-butanol is 1:5. Whereas for n-butanol, it is 1:0.7. The correct TGK for S. quadricauda relative to 2-butanol can only be 95 mg/L, since it is the only value in agreement with the approximated ratios reported in table 3 in the study.

Validity criteria fulfilled:

not applicable

Remarks:

no guideline followed. Dilution series sufficient to determine a dose effect relationship

Conclusions:

The TGK(8 d) equivalent to an EC3 of 2-butanol in the Scenedesmus quadricauda growth inhibition test is 95 mg/L (see remarks on results)

Executive summary:

In this publication a whole array of various organic chemicals has been investigated for efects on aqautic plants. Thus, no distinct positive controls were require and other substances having been assessed proved that the test sytem was suitable to detect effects on green algae. 2 -Butanol has shown little toxicity to green algae (Scenedesmus quadricauda) when exposed over 8 days and the EC3 (reported as toxicity threshold) was reported as being 95 mg/l. This value is taken forward for hazard and risk assessment.

Reference 4

Endpoint:

toxicity to aquatic algae and cyanobacteria

Type of information:

experimental study

Adequacy of study:

weight of evidence

Study period:

1980

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Study without detailed documentation.

Qualifier:

no guideline followed

Principles of method if other than guideline:

The concentration of the algal suspension is measured turbidimetrically and expressed by the extinction of the primary light of the monochromatic radiation at 578 nm for a layer of 10 mm thickness. The concentration at which the inhibitory action of butan-2-ol (SBA) begins is present in that dilution from a series of dilutions of SBA having, at the end of the test period, a mean extinction value that is ≥ 3% below the mean value of the extinction value for non-toxic dilutions of the test cultures.

GLP compliance:

no

Specific details on test material used for the study:

Details on properties of test surrogate or analogue material:
Aluminium tri-sec-butylate reacts instantaneously with water to form 2-butanol and Al3+ species. The resulting pH being weakly alkaline indicates according to Langmuir et al. 2004 that Al3+ species formed are mainly Al(OH)4-, Al(OH)3 and Al(OH)2+ at pH 8.5.
Thus, aluminium tri-sec-butylate is abiotically degradable and forms 2-butanol being readily biodegradable as shown in the registration dossier of 2-butanol submitted by the same lead registrant. Thus, 2-butanol is the ideal surrogate for testing toxicity effects on aquatic plants such as green algae posed by the organic moiety of the reference substance.

Analytical monitoring:

no

Vehicle:

no

Details on test solutions:

Before preparing the test cultures neutralize the butan-2-ol (SBA) solution having a known content in sterile double-distilled water to be tested by using the minimum volume of acid or alkaline solution.

From this SBA solution, prepare dilutions with varying volume ratios using sterile double-distilled water. These dilutions each contain 1 part v/v of the SBA solution in 2E0 to 2E14 parts v/v mixture. When preparing the two parallel dilution series in 300-ml Erlenmeyer flasks proceed as follows: the first flask of each dilution series contains 80 ml of the SBA solution at the start. Starting from this flask, prepare subsequent dilutions using a constant dilution ratio of 40 ml preliminary SBA dilution + 40 ml double-distilled water. So each flask will first contain 40 ml liquid.

Then, complete each flask from the dilution series to be inoculated to the rated value of 50 ml by adding 5 ml each of stock solution I and 5 ml each of the algal suspension of the preliminary culture having a known adjusted extinction value.

Test organisms (species):

Scenedesmus quadricauda

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

7 d

Hardness:

not reported

Test temperature:

27 ºC

pH:

not reported

Dissolved oxygen:

not reported

Salinity:

freshwater

Nominal and measured concentrations:

2 E0 to 2 E14 parts v/v mixtures

Details on test conditions:

Following inoculation, the extinction value of the monochromatic radiation at 578 nm for a 10-mm layer of the algal suspension of the test cultures will correspond to the extinction value of the Formazin standard suspension TE/F/578 nm = 20.

While shaking the contents, transfer from each flask of the inoculated dilution series 10 ml into three Kapsenberg culture tubes (18 x 180 mm), from each flask of the non-inoculated dilution series into one Kapsenberg tube each and stopper culture tubes with metal caps. Keep the filled culture tubes from the dilution series on a white surface protected against daylight and exposed to constant lighting by luminescent worm white tubes at 60 cm distance from each other, at 27ºC and a relative humidity of 50% for 7 days and shake once each day.

Measure the extinction of the monochromatic radiation at 578 mm in a 10-mm layer of the cell suspension from each test culture.

Nutrient solution 1 (for stock and preliminary cultures)
Dissolve in dobule-distilled water:
496 mg sodium nitrate, NaNO3
39 mg dipotassium hydrogen phosphate, K2HPO4 anhydrous
75 mg magnesium sulphate, MgSO4.7 H2O
36 mg calcium chloride, CaCl2.2 H2O
40 mg sodium metasilicate, Na2SiO3
58 mg sodium carbonate Na2CO3, anhydrous
3 mg citric acid C6H8O7.H2O
3 mg iron (III) citrate C6H5FeO7.5 H2O
10 mg disodium salt of ethylene diamine tetracetic acid, C10H14N2Na2O8.2 H2O

Add 10 ml of the trace elements operating solution, complete to 1 litre with double-distilled water and adjust pH to 7.0 using the minimum of Na2CO3 solution.

Stock solution I (for test cultures)
Dissolve in double-distilled water:
248 mg sodium nitrate, NaNO3
19.5 mg disodium hydrogen phosphate, K2HPO4, anhydrous
750 mg magnesium sulphate, MgSO4.7 H2O
360 mg calcium chloride, CaCl2.2 H2O
30 mg iron (III) citrate C6H5FeO7.5 H2O.

Add 10 ml of the trace elements operating solution, complete to 1 liter with double -distilled water and adjust pH to 7.0 using the minimum of Na2CO3 solution.

Stock solution II (trace elements)
Dissolve in double-distilled water:
2.86 g boric acid, H3BO3
1.81 g manganese (II) chloride, MnCl2 . 4 H2O
220 mg zinc sulphate, ZnSO4.7 H2O
80 mg copper (II) sulphate, CuSO4.5 H2O
24 mg sodium molybdate, Na2MoO4.2 H2O
40 mg cobalt (II) chloride, CoCl2.6 H2O

Complete solution with double distilled water to 1 liter in a volumetric flask.

Operating solution of trace elements
Complete 4 ml of stock solution II with double-distilled water to 100 ml in a volumetric flask.

Reference substance (positive control):

no

Duration:

7 d

Dose descriptor:

other: Toxicity threshold

Effect conc.:

95 mg/L

Nominal / measured:

not specified

Conc. based on:

test mat.

Basis for effect:

other: mean extinction value

Details on results:

For evalution of the toxicological findings at the end of the test period, the mean value (A) of the extinction is calculated for all test cultures that are free from both toxic influence and stimulation of growth except for those having extinction values outside a standard deviation of <3% and also, the mean value (B) of the extinction for those test cultures having the lowest toxic pollutant concentration within the dilution series.

For mathematical evaluation, (a) (highest non-toxic pollutant concentration) is plotted against (A) and (b) (lowest toxic pollutant concentration) against (B) as coordinates. After having entered (A - 3%), the pollutant concentration at which the inhibitory action (c) begins may be obtained from the regression line between (a;A) and (b;B) if a negative deviation of the mean extinction by a 3% difference against the mean extinction value of all test cultures having a non-toxic and non-stimulating pollutant concentration is used as an indicator of the beginning of inhibitory action.

Validity criteria fulfilled:

not applicable

Conclusions:

The toxicity threshold (EC3) for 2-butanol is 95 mg/l (Scenedesmus quadricauda) following exposure during 7 days in this published study.

Executive summary:

In this publication a whole array of various organic chemicals has been investigated for effects on aqautic plants. Thus, no distinct positive controls were require and other substances having been assessed proved that the test sytem was suitable to detect effects on green algae. 2-Butanol has shown little toxicity to green algae when exposed over 7 days and the EC3 (reported as toxicity threshold) was reported as being 95 mg/l. This value is taken forward for hazard and risk assessment.

Description of key information

Aluminium tri-sec-butanolate dissociates instantaneously when exposed to water forming butan-2-ol and soluble aluminium(III) species. Therefore the effects of both hydrolysis products are considered most relevant to assess the toxicity of aluminium tri-sec-butanolate.

For Chlorella sp. the 72 h EC50 values for bulk alumina is 110.2 mg/L. was noted. For Scenedesmus sp. the 72 h EC50 values was 100.4 mg/l. A concentration-dependent decrease in total chlorophyll content was observed in both species (Sadiq 2011).

The EC50 for growth rate in fresh water species Monoraphidium dybowskii and Stichococcus sp. is 0.54-1.1 mg/L. The NOEC is 0.04-0.23 mg/L (Claesson 1988).

The toxicity of Al to the chronic growth rate of marine microalgae was assessed with IC10 values between 18 and 3200 µg Al/L. The microalgal species ranked in sensitivity to Al as follows: C. closterium > M. polymorphus > D. teriolecta > Tetraselmis sp. Toxicity appears to be more strongly related to dissolved Al with potential contributions from particulate Al at total concentrations of <100 µg/L (Golding 2015). 72h IC10 for P. tricornutum (marine species) was 2100 (2000-2000) µg/L and IC50 was >9500 µg/L.  Toxicity to this diatom was due predominantly to precipitated aluminium under the test conditions (Gillmore 2016).

The toxicity threshold of sec-butanol was determined as 95 mg/L for Scenedesmus quadricauda (green algea) by a cell multiplication inhibition test during 8 days (Bringmann 1977/1980).

Key value for chemical safety assessment

EC50 for freshwater algae:

0.54 mg/L

EC10 or NOEC for freshwater algae:

40 µg/L

EC10 or NOEC for marine water algae:

18 µg/L

Additional information

Aluminium tri-sec-butanolate reacts instantaneously with water to form butan-2-ol and Al3+ species. The resulting pH being weakly alkaline indicates according to Langmuir et al. 2004 that Al3+ species formed are mainly Al(OH)4-, Al(OH)3 and Al(OH)2+ at pH 8.5.

Thus, aluminium tri-sec-butanolate is abiotically degradable and forms sec-butanol being readily biodegradable as shown in a publication by Bridie (1979).

Hence, both butanol and aluminium species will be present in aqueous media. Based on its toxicity, aluminium species seem to represent a worst case surrogate for assessing toxicity to aquatic species exposed to the substance, aluminium tri-sec-butanolate.