Propan-2-ol

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:

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 the test material begins is present in that dilution from a series of dilutions of the test material 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

Analytical monitoring:

no

Vehicle:

no

Details on test solutions:

Before preparing the test cultures neutralize the test material 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 test material solution, prepare dilutions with varying volume ratios using sterile double-distilled water. These dilutions each contain 1 part v/v of test material 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 test material solution at the start. Starting from this flask, prepare subsequent dilutions using a constant dilution ratio of 40 ml preliminary test material 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:

27ºC

pH:

not reported

Dissolved oxygen:

not reported

Salinity:

freshwater

Nominal and measured concentrations:

2E0 to 2E14 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 warm 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 double-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.:

1 800 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 test material concentration within the dilution series.

For mathematical evaluation, (a) (highest non-toxic test material concentration) is plotted against (A) and (b) (lowest toxic test material concentration) against (B) as coordinates. After having entered (A - 3%), the test material 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 test material concentration is used as an indicator of the beginning of inhibitory action.

Validity criteria fulfilled:

not applicable

Description of key information

The substance was not toxic to algae when tested according to non-specific methods, the substance was determined to possess a 7 day toxicity threshold, approximately equivalent to the LC₃, of 1800 mg/L.

Key value for chemical safety assessment

EC10 or NOEC for freshwater algae:

1 800 mg/L

Additional information

Four studies addressing toxicity to aquatic algae and cyanobacteria are presented in the dossier.

Toxicity to aquatic algae and cyanobacteria.001- Scenedesmus – 1980 – key: Acute toxicity to Scenedesmus quadricauda was assessed according to non-specific guidelines and not according to GLP (pre-dates GLP requirements).  Algae were exposed to the substance at a range of concentrations in dilution water (1 part v/v of pollutant solution in 2 to 2 x 10¹⁴ parts v/v mixture). The toxic effect measured during the assay was the mean extinction over a time period of 7 days. The study was performed under static conditions using 300 mL glass Erlenmeyer flasks, containing 50 mL of test solution with the algal suspension of the preliminary culture having a known adjusted extinction value.  Test flasks were stoppered with metal caps, incubated at 27°C, and shaken once each day. The extinction value of monochromatic radiation at 578 nm for a 10-mm layer of algal suspension was determined. The toxicity threshold (approximately equivalent to the LC₃) based on mean extinction value was determined to be 1800 mg/L.

Toxicity to aquatic algae and cyanobacteria.002 Scenedesmus – 1976: Acute toxicity to Scenedesmus quadricauda was assessed according to non-specific guidelines and not according to GLP (pre-dates GLP requirements). Algae were exposed to the substance under static conditions for 8 days. The toxicity threshold based on growth inhibition was determined to be 1800 mg/L. This lower toxicity over a shorter exposure period is in keeping with the result of the key study.

Toxicity to aquatic algae and cyanobacteria.003 – Microcystis – 1978: Acute toxicity to Microcystis aeruginosa was assessed according to non-specific guidelines and not according to GLP (pre-dates GLP requirements). Algae were exposed to the substance under static conditions for 8 days. The toxicity threshold based on growth inhibition was determined to be 1000 mg/L. This lower toxicity over a shorter exposure period is in keeping with the result of the key study.

Toxicity to aquatic algae and cyanobacteria.004 – Scenedesmus – 1978: Acute toxicity to Scenedesmus quadricauda was assessed according to non-specific guidelines and not according to GLP (pre-dates GLP requirements). Algae were exposed to the substance under static conditions for 8 days. The toxicity threshold based on growth inhibition was determined to be 1800 mg/L. This lower toxicity over a shorter exposure period is in keeping with the result of the key study.