ALFERROCK

Toxicity to microorganisms

Link to relevant study record(s)

Reference

Endpoint:

toxicity to microorganisms, other

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

key study

Justification for type of information:

For details and justification of read-across please refer to the read-across report attached to IUCLID section 13.

Reason / purpose for cross-reference:

read-across source

Duration:

9 h

Dose descriptor:

IC50

Effect conc.:

ca. 15 mg/L

Nominal / measured:

nominal

Conc. based on:

element

Basis for effect:

other: motility, mortality

Remarks on result:

other: AlCl3

Key result

Duration:

9 h

Dose descriptor:

IC50

Effect conc.:

ca. 10 mg/L

Nominal / measured:

nominal

Conc. based on:

element

Basis for effect:

other: motility, mortality

Remarks on result:

other: Al2(SO4)3

Duration:

9 h

Dose descriptor:

IC50

Effect conc.:

ca. 14 mg/L

Nominal / measured:

nominal

Conc. based on:

element

Basis for effect:

other: motility, mortality

Remarks on result:

other: Al(NO3)3

Duration:

9 h

Dose descriptor:

IC50

Effect conc.:

ca. 495 mg/L

Nominal / measured:

nominal

Conc. based on:

element

Basis for effect:

other: motility, mortality

Remarks on result:

other: Al2O3

Details on results:

EFFECTS OF ALUMINIUM ON THE GROWTH RATE OF TETRAHYMENA PYRIFORMIS
The doubling time of test organisms was < 3 h without the addition of aluminium. Aluminium affected the doubling rate in a dose-dependent relationship and led to a decrease of motility and swimming speed. Major differences between the toxicity of aluminium salt and oxides have been reported, due to the different solubility of the substances.
- aluminium chloride: IC50 = 15 µg/ml
- aluminium sulphate: IC50 = 10 µg/ml
- aluminium nitrate: IC50 = 14 µg ml
- aluminium oxide: IC50 = 495 µg/ml

Reported statistics and error estimates:

Results are expressed as mean values of at least five experiments and the IC50 values were calculated by regression analysis. Student’s t-test was used for statistical evaluation of the data of the TP cultured with Al chelates, in comparison with the control TP cultured without chelators. All calculations were performed with Statview 4.02®, computed on Macintosh IIx.

For cell densities about 10E+04 cells/ml, the normal doubling time of TP population was less than 3 h. Addition of aluminium salts to the culture medium affected the growth rate and the doubling time of T. pyriformis in a dose-dependent relationship, concomitantly with a decrease of the motility and the swimming speed during the exposure to the highest concentrations of Al. Great differences in cytotoxicity induced by Al existed between the soluble salts (chloride, sulphate and nitrate), for which the IC50 values were, respectively, 15, 10 and 14 mg Al/ml and the insoluble salt (oxide), for which the IC50 value was 495 mg Al/ml.

Validity criteria fulfilled:

not applicable

Remarks:

Non-guideline study, but scientifically robust result published in peer-reviewed article.

Conclusions:

A study was performed to determine the toxicity of various soluble (AlCl3, Al2(SO4)3, Al(NO3)3) aluminium salts and one weakly soluble (Al2O3) aluminium oxide against the cosmopolitan fresh water ciliated protozoa Tetrahymena pyriformis. The inhibitory concentrations (IC50) were determined to:
- aluminium chloride: IC50 = 15 µg Al/ml
- aluminium sulphate: IC50 = 10 µg Al/ml
- aluminium nitrate: IC50 = 14 µg Al/ml
- aluminium oxide: IC50 = 495 µg Al/ml

Executive summary:

A study was performed to determine the toxicity of various soluble (AlCl₃, Al₂(SO₄)₃, Al(NO₃)₃) aluminium salts and one poorly soluble (Al₂O₃) aluminium oxide towards microorganisms. The ciliated protozoa T. pyriformis strain GL (TP) was grown axenically, without shaking, in the proteose-peptone yeast substrate defined medium (PPYS) supplemented with inorganic salts. The cultures were incubated at 28 °C in capped 500 ml Fernbach flasks containing 100 ml of PPYS medium. For the bioassays the cell density was adjusted to 1.0E+04 cells/mL and cells were used in a exponential growth phase. One millilitre aliquots were immediately (t₀) withdrawn from the control (untreated culture) and the treated cultures, then every hour for 9 h. The samples were fixed with 1 ml 4 % formaldehyde in Isoton® buffer and the cell number was determined by counting with an electronic cell counter.

The inhibitory concentration (IC₅₀) was determined to:

- aluminium chloride: IC₅₀= 15 µg Al/ml

- aluminium sulphate: IC₅₀= 10 µg Al/ml

- aluminium nitrate: IC₅₀= 14 µg Al/ml

- aluminium oxide: IC₅₀= 495 µg Al/ml

This information is used in a read-across approach in the assessment of the target substance. For details and justification of read-across please refer to the read-across report attached to IUCLID section 13.

Description of key information

Toxicity of "Neutralisation and reduction products of bauxite residue from refinement process" to aquatic microorganisms can be elicited by aluminium ions released from the material during dissolution. Studies existing in the literature were used for the purpose of read-across for Aluminium in "Neutralisation and reduction products of bauxite residue from refinement process". 
A study was identified in which various soluble (AlCl3, Al2(SO4)3, Al(NO3)3) aluminium salts and one poorly soluble (Al2O3) aluminium oxide were exposed to the ciliated protozoon Tetrahymena pyriformis. 
The inhibitory concentrations (IC50) were determined to be 15 µg Al/ml (AlCl3), 10 µg Al/ml (Al2(SO4)3), 14 µg Al/ml (Al(NO3)3) and 495 µg Al/ml (Al2O3), in terms of aluminium, respectively.

Key value for chemical safety assessment

EC50 for microorganisms:

10 mg/L

Additional information

Toxicity of "Neutralisation and reduction products of bauxite residue from refinement process" to microorganisms can be elicited by aluminium ions released from the material during dissolution under aqueous conditions. 

A study was performed to determine the toxicity of various soluble (AlCl₃, Al₂(SO₄)₃, Al(NO₃)₃) aluminium salts and one poorly soluble (Al₂O₃) aluminium oxide towards microorganisms.

The ciliated protozoon T. pyriformis, strain GL (TP), was grown under axenic conditions, without shaking, in the proteose-peptone yeast substrate defined medium (PPYS) supplemented with inorganic salts. The cultures were incubated at 28 °C in capped 500 ml Fernbach flasks containing 100 ml of PPYS medium. For the bioassays the cell density was adjusted to 1.0E+04 cells/mL and cells were used in the exponential growth phase. Aliquots of one millilitre were immediately (t₀) withdrawn from the control (untreated) and the treated cultures, then every hour for 9 h. The samples were fixed with 1 ml of 4 % formaldehyde in Isoton® buffer and the cell number was determined by counting with an electronic cell counter.

The inhibitory concentration (IC₅₀) was determined to:

- aluminium chloride: IC₅₀= 15 µg Al/ml

- aluminium sulphate: IC₅₀= 10 µg Al/ml

- aluminium nitrate: IC₅₀= 14 µg Al/ml

- aluminium oxide: IC₅₀= 495 µg Al/ml