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Ecotoxicological information

Toxicity to aquatic algae and cyanobacteria

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Reference
Endpoint:
toxicity to aquatic algae and cyanobacteria
Type of information:
read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
supporting study
Justification for type of information:
Crude sulfate turpentine is a UVCB substance that contains the same main constituents as gum turpentine oil. Therefore, data on crude sulfate turpentine can be extrapolated to gum turpentine oil. See read-across justification document in section 13.
Reason / purpose for cross-reference:
read-across source
Post exposure observation period:
None
Duration:
72 h
Dose descriptor:
EL50
Effect conc.:
17.1 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Remarks:
Water Accommodated Fractions (WAFs)
Basis for effect:
growth rate
Duration:
72 h
Dose descriptor:
EL50
Effect conc.:
16.4 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Remarks:
Water Accommodated Fractions (WAFs)
Basis for effect:
biomass
Remarks:
(yield)
Duration:
72 h
Dose descriptor:
NOELR
Effect conc.:
10 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Remarks:
Water Accommodated Fractions (WAFs)
Basis for effect:
other: growth rate and biomass (yield)
Details on results:
- Exponential growth in the control: yes, the cell concentration in the control cultures increased by a factor of 230 in 72 h.

- Effect concentrations exceeding solubility of substance in test medium: the loading rates at which the water-accommodated fractions were prepared exceeded the solubility of the test substance.
Reported statistics and error estimates:
The results of the Alga Test were analysed statistically with reference to the specific growth rate [µ] and biomass (yield).

Normality of the data was tested using a Kolmogorov-Smirnov-test (α = 0.05).

Homogeneity of variances was tested by Bartlett`s test (α = 0.05).

For all measured end values, statistical differences among treatment groups were determined using a one-way analysis of variance (ANOVA).

Two-sided Dunnet's procedure for multiple comparison was used to determine, which concentration of the test item differed significantly from the control (p = 0.05).

The results of the two-sided Dunnet's test (p = 0.05) were used to determine the NOELR (No Observable Effect Loading Rate) of the specific growth rate [µ] and of the biomass (yield).

The NOELR (No Observable Effect Loading Rate) is defined as the highest test loading rate, where inhibition of the specific growth rate [µ] and of the biomass was statistically not significantly different when compared to the control.

Table 1. Test results – average specific growth rates (µ) over the test period 0-72 hours

Loading rate

[mg/L]

Cells / mL

Average

Specific

growth rate

[µ]

Average

Specific

growth rate

[µ]

Mean value

Standard deviation

Coefficient of variation

Vc [%]

Inhibition of Average

Specific

growth rate

[%]

Inhibition of Average

Specific

growth rate

Mean value

[%]

Control 1

576000

1.81

1.81

0.00

0.15

 

 

Control 2

568000

1.81

Control 3

576000

1.81

5.0

584000

1.82

1.81

0.01

0.45

-0.34

-0.08

5.0

560000

1.80

0.43

5.0

584000

1.82

-0.34

10

568000

1.81

1.80

0.01

0.68

0.17

0.79

10

528000

1.78

1.52

10

552000

1.80

0.70

25

5000

0.23

0.15

0.09

57.1

87.3

91.8

25

3000

0.06

96.7

25

4000

0.16

91.4

50

4500

0.20

0.10

0.10

95.7

89.2

94.3

50

2500

0.00

100

50

3500

0.11

93.8

100

3000

0.06

0.09

0.06

59.7

96.7

94.9

100

3000

0.06

96.7

100

4000

0.16

91.4

 Remark: A negative inhibition value means an enhancement of the parameter.

Table 2. Test results – biomass (yield) over the whole test period 0-72 hours

Loading rate

[mg/L]

Cells/mL

Yield

Cells/mL

Yield

Cells/mL

Mean value

Standard deviation

Coefficient of variation

Vc [%]

Inhibition

of Yield [%]

Inhibition of Yield [%] Average

Control 1

576000

573500

570833

4619

0.81

 

 

Control 2

568000

565500

Control 3

576000

573500

5.0

584000

581500

573500

13856

2.42

-1.87

-0.47

5.0

560000

557500

2.34

5.0

584000

581500

-1.87

10

568000

565500

546833

20133

3.68

0.93

4.20

10

528000

525500

7.94

10

552000

549500

3.74

25

5000

2500

1500

1000

66.7

99.6

99.7

25

3000

500

99.9

25

4000

1500

99.7

50

4500

2000

1000

1000

100

99.7

99.8

50

2500

0

100

50

3500

1000

99.8

100

3000

500

833

577

69.3

99.9

99.9

100

3000

500

99.9

100

4000

1500

99.7

 Remark: A negative inhibition value means an enhancement of the parameter.

Table 3. Results of TOC analysis of the test media

Time [h]

Control

5.0 mg/L

25 mg/L

100 mg/L

0

0.3

0.3

1.7

4.7

72

0.3

0.1

1.2

3.8

 

Table 4. Results of GC-MS analysis of test media

Vessel

Time [h]

a-Terpineol
[µg/L]

a-Pinene
[µg/L]

b-Pinene
[µg/L]

3-Carene
[µg/L]

Limonene
[µg/L]

Total

[µg/L]

Control

0

0.214**

< 0.367*

0.227**

< 0.151*

0.212**

< 1.17

Control

72

0.214**

< 0.367*

0.227**

< 0.151*

0.212**

< 1.17

5.0 mg/L

0

5.81

94.1

10.1

23.2

9.12

142

5.0 mg/L

72

3.76

11.1

2.32

7.12

2.82

27.1

25 mg/L

0

37.6

735

75.3

222

96.1

1166

25 mg/L

72

22.5

116

22.8

84.5

38.4

285

100 mg/L

0

125

1111

116

243

113

1708

100 mg/L

72

104

173

32.7

81.6

41.5

432

Remarks:

*   Limit of detection

**   derived from equation of the calibration line (axis intercept); no signal was measured in the controls for α-Terpineol, β-Pinene and Limonene

         Quantitative GC-MS-values are based on results and/or limits of detection

Validity criteria fulfilled:
yes
Conclusions:
A 72h EL50 of 17.1 mg/L and NOELr of 10 mg/L have been determined for the effect of the test substance on growth rate of Desmodesmus subspicatus.
Executive summary:

An algal toxicity study was performed in accordance with OECD guideline 201 and GLP. Algal cells (Desmodesmus subspicatus) were exposed to Water Accommodated Fractions (WAFs) of the test item, over a range of nominal loading values of 5, 10, 25, 50 and 100 mg/L. The inhibition of growth in relation to control cultures was determined over a test period of 72 h, and thus several algal generations, in closed test vessels.

The EL50 and NOELr at 72 h for the test item to algae (Desmodesmus subspicatus) based on the nominal loading rates were determined to be 17.1 and 10 mg/L, respectively.

Description of key information

A 72-h EL50 of 17.1 mg/L and a NOELR of 10 mg/L have been determined for the effect of Crude Sulfate Turpentine on growth rate of Desmodesmus subspicatus.

Key value for chemical safety assessment

EC50 for freshwater algae:
17.1 mg/L
EC10 or NOEC for freshwater algae:
10 mg/L

Additional information