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Toxicity to aquatic algae and cyanobacteria

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Reference
Endpoint:
toxicity to aquatic algae and cyanobacteria
Type of information:
experimental study
Adequacy of study:
key study
Study period:
1997-03-10 trough 1997-03-28
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to
Guideline:
OECD Guideline 201 (Alga, Growth Inhibition Test)
Deviations:
no
GLP compliance:
yes
Analytical monitoring:
yes
Details on sampling:
no data
- Concentrations: all
- Sampling method: aliquots were sampled from the intermediate layer of 3 test vessels per concentration and pooled, at start and at the end of the exposure. Algae were then removed by centriguation (10 minutes at 3000 rpm). The clear supernatant was taken for GC analysis.
Vehicle:
yes
Details on test solutions:
PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Method: A 1000 mg/L stock solution was prepared by dissoving one part of isononanol and two parts of hydrogenated castor oil in acetone. Culture medium was use dto fill up to 1 L.
- Controls:
- Chemical name of vehicle: hydrogenated castor oil (HCO-40), acetone
- Concentration of vehicle in test medium: HCO-40 twice the concentration of isononanol.
- Evidence of undissolved material: no.
Test organisms (species):
Scenedesmus capricornutum
Details on test organisms:
TEST ORGANISM
- Common name: green alga
- Strain: ATCC 22662
- Source (laboratory, culture collection): strain obtained from American Type Culture collection, Rockville, Maryland, USA, and sub-cultured at the test facility.
- Age of inoculum (at test initiation): pre-culture was started 3 days before test initiation.

ACCLIMATION
- Acclimation period: 3 days
- Culturing media and conditions (same as test or not): yes
- Any deformed or abnormal cells observed: no
Test type:
static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
72 h
Hardness:
The culture medium indicated in OECD Guidelines for Testing of Chemicals is used in pre-culture and test.
Ca+Mg >/= 0.6 mmol/L
Test temperature:
23 ± 2°C
pH:
pH=8.1 at initiation. Increase up ro 9.4 at 72 hrs (report, table 7).
Dissolved oxygen:
No data; vessels were shaken at 100 rpm
Salinity:
The culture medium indicated in OECD Guidelines for Testing of Chemicals is used in pre-culture and test.
Nominal and measured concentrations:
Nominal concentrations, corrected for the test substance purity:
0, 2.13, 4.70, 10.3, 22.7, and 50.0 mg/L
Details on test conditions:
TEST SYSTEM
- Test vessel:
- Type: open
- Material, size, headspace, fill volume: 500 mL conical flask made of glass (with permeable silicon stopper)
- Aeration: shaking at 100 rpm
- Renewal rate of test solution: n.a.; static test
- Initial cells density: 1 × 104 cells / mL
- Control end cells density: 90.4 × 104 cells / mL
- No. of vessels per concentration (replicates): 3
- No. of vessels per control (replicates): 3
- No. of vessels per vehicle control (replicates): 3

GROWTH MEDIUM
- Standard medium used: yes (OECD TG 201 medium)

- Adjustment of pH: no
- Photoperiod: continuos
- Light intensity and quality: 4,400 ~ 4,500 lux

EFFECT PARAMETERS MEASURED
- Determination of cell concentrations: using an optical microscope; determinations at 0, 24, 48, 72 hrs

TEST CONCENTRATIONS
- Spacing factor for test concentrations: 2.2
- Range finding study
- Test concentrations: 50 mg/L caused 80% growth inhibition
- Results used to determine the conditions for the definitive study: yes; main test concentrations
Reference substance (positive control):
no
Duration:
72 h
Dose descriptor:
other: ErC50 (24-72h)
Effect conc.:
> 33.3 mg/L
Nominal / measured:
meas. (TWA)
Conc. based on:
act. ingr.
Basis for effect:
biomass
Duration:
72 h
Dose descriptor:
NOEC
Effect conc.:
4.7 mg/L
Nominal / measured:
meas. (TWA)
Conc. based on:
act. ingr.
Basis for effect:
biomass
Duration:
72 h
Dose descriptor:
other: EbC50 (0-72h)
Effect conc.:
12.6 mg/L
Nominal / measured:
meas. (TWA)
Conc. based on:
act. ingr.
Basis for effect:
cell number
Remarks on result:
other: 14.8-25.8 mg/L
Duration:
72 h
Dose descriptor:
NOEC
Effect conc.:
10.3 mg/L
Nominal / measured:
meas. (TWA)
Conc. based on:
act. ingr.
Basis for effect:
growth rate
Details on results:
- Exponential growth in the control (for algal test): yes
- Any stimulation of growth found in any treatment: no
- Effect concentrations exceeding solubility of substance in test medium: no

Test article concentration and quantity are shown with purity corection value.

Nominal/measured Concentration:

Measured concentration (mg/L)

(percentage of nominal)

Nominal

concentration

(mg/L)

0-hour

24-hour

Mean*

control

n.d.

n.d.

n.d.

Solvent control

n.d.

n.d.

n.d.

2.13

2.16

(102)

n.d.(0.923)

(43.3)

1.46

(68.4)

4.70

4.53

(96.3)

1.80

(38.2)

2.95

(62.8)

10.3

9.08

(88.2)

4.61

(44.8)

6.60

(64.1)

22.7

21.8

(96.2)

9.37

(41.3)

14.7

(64.9)

50.0

46.8

(93.5)

22.8

(45.5)

33.3

(66.7)

n.d.:<1.00 mg/L

* The value are expressed as time-weighted means

Water Temperature: 23.2-23.8 °C

Water Chemistry in test: pH 8.1 at start and 8.2-9.4 end of the test

Effect Data:

Area method:

EbC50 (0-72hr) = 19.5 mg/L (95% c.i.:14.8-25.8mg/L); 12.6 mg/L (measured concentration)

NOEC = 4.70 mg/L (measured concentration)

Rate method:

ErC50 (24-48hr)= 49.9 mg/L (95% c.i.:none)

ErC50 (24-72hr) > 50 mg/L (95% c.i.:none)

NOEC = 10.3 mg/L (measured concentration)

Detail information:

(1) Cell density of Selenastrum capricornutum during exposure to 3,5,5-trimethyl-1-hexanol:

cell density(X10E+4 cells/ml)

Nominal

concentration

(mg/L)

No.

0-hour

24-hour

48-hour

72-hour

control

1

2

3

1.0

1.0

1.0

3.1

3.4

2.9

22.6

22.5

20.2

96.0

91.9

83.3

Average S.D.

1.0

0.0

3.2

0.2

21.7

1.3

90.4

6.5

Solvent control

1
2

3

1.0

1.0

1.0

3.0

3.3

3.3

21.8

21.5

21.4

103.2

96.5

85.8

Average S.D.

1.0

0.0

3.2

0.1

21.6

0.2

95.2

8.8

2.13

1

2

3

1.0

1.0

1.0

3.4

3.1

3.1

21.1

23.8

20.7

89.8

93.1

99.1

Average S.D.

1.0

0.0

3.2

0.1

21.9

1.7

94.0

4.7

4.70

1

2

3

1.0

1.0

1.0

3.2

2.9

3.4

21.3

19.6

20.4

86.0

85.5

99.7

Average S.D.

1.0

0.0

3.2

0.2

20.4

0.8

90.4

8.1

10.3

1

2

3

1.0

1.0

1.0

2.5

2.7

2.5

14.8

17.7

16.7

66.2

64.6

66.2

Average S.D.

1.0

0.0

2.6

0.1

16.4

1.5

65.7

0.9

22.7

1

2

3

1.0

1.0

1.0

2.4

2.6

2.3

10.0

10.8

10.9

48.1

47.6

42.3

Average S.D.

1.0

0.0

2.4

0.2

10.6

0.5

46.0

3.2

50.0

1

2

3

1.0

1.0

1.0

1.5

1.7

1.8

4.2

4.4

4.1

11.6

11.9

11.2

Average S.D.

1.0

0.0

1.5

0.2

4.2

0.1

11.6

0.3

(2) Growth inhibition of Selenastrum capricornutum during exposure to 3,5,5-trimethyl-1-hexanol:

Area Inhibition Rate Inhibition (x10E+4)

Nominal

concentration

(mg/L)

No.

0-72h

%

24-72h

%

control

1

2

3

1710

1660

1500

-

-

-

0.0712

0.0687

0.0696

-

-

-

Average S.D.

1620

-

0.0698

-

Solvent control

1
2

3

1780

1690

1560

-9.41

-4.35

3.73

0.0734

0.0750

0.0680

-5.11

-0.982

2.68

Average S.D.

1680

-3.34

0.0706

-1.14

2.13

1

2

3

1610

1700

1700

1.08

-4.87

-4.77

0.0685

0.0709

0.0721

1.93

-1.53

-3.27

Average S.D.

1670

-2.85

0.0705

-0.957

4.70

1

2

3

1560

1510

1710

3.87

7.13

-5.16

0.0683

0.0704

0.0706

2.20

-0.854

-1.03

Average S.D.

1590

1.95

0.0698

0.105

10.3

1

2

3

1150

1210

1200

29.2

25.7

26.3

0.0682

0.0661

0.0679

2.23

5.35

2.81

Average S.D.

1180

27.1

0.0674

3.50

22.7

1

2

3

814

833

762

49.9

48.6

53.0

0.0628

0.0604

0.0610

10.0

13.5

12.6

Average S.D.

803

50.5

0.0614

12.0

50.0

1

2

3

216

229

216

86.7

85.9

86.7

0.0427

0.0399

0.0384

38.9

42.9

45.0

Average S.D.

220

86.4

0.0403

42.3

Validity criteria fulfilled:
yes
Conclusions:
Acute toxicity to algae:
EbC50 (0 -72 h) = 19.5 mg/L (measured concentration)
ErC50 (24 -72 h) >50 mg/L (measured concentration)
Executive summary:

The acute toxicity to algae was tested according to OECD TG 201using Selenastrum capricomutum under GLP conditions in the concentration range up to 50 mg/L (nominal). The calculated growth inhibition was as follows

EbC50 (0 -72 h) = 19.5 mg/L (measured concentration)

ErC50 (24 -72 h) >50 mg/L (measured concentration) (CERI, 1997)

This study is considered to be valid and suitable for assessment.

Description of key information

The acute toxicity to algae was as follows (CERI, 1997):
ErC50 (24 -72 h) >50 mg/L (measured concentration)
EbC50 (0 -72 h) = 19.5 mg/L (measured concentration)

Key value for chemical safety assessment

EC50 for freshwater algae:
50 mg/L

Additional information

The acute toxicity to algae was tested according to OECD TG 201using Selenastrum capricomutum under GLP conditions in the concentration range up to 50 mg/L (nominal). The calculated growth inhibition was as follows

EbC50 (0 -72 h) = 19.5 mg/L (measured concentration)

ErC50 (24 -72 h) >50 mg/L (measured concentration) (CERI, 1997)

This study is considered to be valid and suitable for assessment.