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Toxicity to aquatic algae and cyanobacteria

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Endpoint:
toxicity to aquatic algae and cyanobacteria
Type of information:
migrated information: read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
key study
Study period:
10 January 2011 - 03 February 2011
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to
Guideline:
OECD Guideline 201 (Alga, Growth Inhibition Test)
Deviations:
no
Qualifier:
according to
Guideline:
EU Method C.3 (Algal Inhibition test)
Deviations:
no
Qualifier:
according to
Guideline:
ISO 8692 (Water Quality - Fresh Water Algal Growth Inhibition Test with Scenedesmus subspicatus and Selenastrum capricornutum)
Deviations:
no
GLP compliance:
yes
Specific details on test material used for the study:
Details on properties of test surrogate or analogue material (migrated information):
Stability in water: Not indicated
The water solubility at 20°C was determined to be 0.109 g/l using the flask method.
Analytical monitoring:
yes
Details on sampling:
Samples for possible analysis were taken from all test concentrations and the control according to the schedule below. In addition, the filter containing undissolved residue was kept for possible analysis.

Frequency: at t=0 h, t=24 h and t=72 h
Volume: 2 ml
Storage: Samples were stored in a freezer until analysis.

At the end of the exposure period, the replicates with algae were pooled at each concentration before sampling.

Compliance with the Quality criteria regarding maintenance of actual concentrations was demonstrated by running a test vessel at the highest substance concentration but without algae and samples for analysis were taken at the start, after 24 hours of exposure and at the end of the test period.
Vehicle:
no
Details on test solutions:
The batch of LIN10001:4,4’-Isopropylidenediphenol, propoxylated tested was a white powder with lumps and a purity >95%. The test substance was not completely soluble in test medium at the at the loading rate initially prepared.

Preparation of test solutions started with a loading rate of 100 mg/l applying a two-day period of magnetic stirring followed a filtration through a 0.45 µm membrane filter (rs55, Whatman) to remove undissolved material. The lower test concentrations were prepared by subsequent dilutions of the highest loading rate in test medium. The final test solutions were all clear and colourless.
Test organisms (species):
Pseudokirchneriella subcapitata (previous names: Raphidocelis subcapitata, Selenastrum capricornutum)
Details on test organisms:
Species: Pseudokirchneriella subcapitata, strain: NIVA CHL 1

Source: In-house laboratory culture.

Reason for selection: This system is an unicellular algal species sensitive to toxic substances in the aquatic ecosystem and has been selected as an internationally accepted species.

Pre-culture: 3 days before the start of the test, cells from the algal stock culture were inoculated in culture medium at a cell density of 1 x 104 cells/ml. The pre-culture was maintained under the same conditions as used in the test. The cell density was measured immediately before use.

Pre-culture medium: M2; according to the OECD 201 Guideline, formulated using Milli-Q water (tap water purified by reverse osmosis (Milli-RO) and subsequently passed over activated carbon and ion-exchange cartridges: Milli-Q water; Millipore Corp., Bedford, Mass., USA) preventing precipitation and with the following composition:
NH4Cl 15 mg/l
MgCl2.6H2O 12 mg/l
CaCl2.2H2O 18 mg/l
MgSO4.7H2O 15 mg/l
KH2PO4 1.6 mg/l
FeCl3.6H2O 64 µg/l
Na2EDTA.2H2O 100 µg/l
H3BO3 185 µg/l
MnCl2.4H2O 415 µg/l
ZnCl2 3 µg/l
CoCl2.6H2O 1.5 µg/l
CuCl2.2H2O 0.01 µg/l
Na2MoO4.2H2O 7 µg/l
NaHCO3 50 mg/l
Hardness (Ca+Mg) 0.24 mmol/l (24 mg CaCO3/l)
pH 8.1 ± 0.2
Test type:
static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
72 h
Post exposure observation period:
none
Hardness:
0.24 mmol/l (24 mg CaCO3/l)
Test temperature:
between 22.1 and 22.9°C
pH:
8.0 -8.2
Dissolved oxygen:
not measured
Salinity:
not measured
Nominal and measured concentrations:
Nominal concentrations: A 0.45 µm filtered solution prepared at a loading rate of 100% and 1.0, 3.2, 10 and 32% dilutions thereof.

Measured concentrations: At the start of the test, the actual test concentrations were 0.8, 2.5, 7.9, 26 and 83 mg/l in 1.0, 3.2, 10, 32 and 100% of the filtrate. Measured concentrations remained constant during the test (86-104% of initial).
Details on test conditions:
Test vessels: 100 ml, all-glass, containing 50 ml of test solution

Medium: M2

Cell density: An initial cell density of 1 x 104 cells/ml.

Illumination: Continuously using TLD-lamps of the type ‘Cool-white’ of 30 Watt, with a light intensity within the range of 87 to 100 uE.m-2.s-1.

Incubation: Vessels were distributed at random in the incubator. During incubation the algal cells were kept in suspension by continuous shaking.
Reference substance (positive control):
yes
Remarks:
potassium dichromate
Key result
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
28 mg/L
Nominal / measured:
meas. (initial)
Conc. based on:
test mat.
Basis for effect:
growth rate
Remarks on result:
other: 11-71
Duration:
72 h
Dose descriptor:
EC10
Effect conc.:
5.1 mg/L
Nominal / measured:
meas. (initial)
Conc. based on:
test mat.
Basis for effect:
growth rate
Remarks on result:
other: 2.0-13
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
8.5 mg/L
Nominal / measured:
meas. (initial)
Conc. based on:
test mat.
Basis for effect:
other: yield
Remarks on result:
other: 5.3-14
Duration:
72 h
Dose descriptor:
EC10
Effect conc.:
2.8 mg/L
Nominal / measured:
meas. (initial)
Conc. based on:
test mat.
Basis for effect:
other: yield
Remarks on result:
other: 1.7-4.6
Duration:
72 h
Dose descriptor:
NOEC
Effect conc.:
2.5 mg/L
Nominal / measured:
meas. (initial)
Conc. based on:
test mat.
Basis for effect:
growth rate
Remarks on result:
other: .
Duration:
72 h
Dose descriptor:
NOEC
Effect conc.:
2.5 mg/L
Nominal / measured:
meas. (initial)
Conc. based on:
test mat.
Basis for effect:
other: yield
Remarks on result:
other: .
Details on results:
Growth rates were in the range of the controls at the two lowest concentrations 72-hour test period, whereas the growth rate of algae exposed to 7.9 mg/l and higher were increasingly reduced.
Statistically significant reduction of growth rate was found at test concentrations of 7.9 mg/l and higher (Bonferroni t- test, α = 0.05).

Inhibition of yield increased with increasing concentration of LIN10001:4,4’-Isopropylidenediphenol, propoxylated from 7.9 mg/l upwards resulting in 99% inhibition at 83 mg/l. Statistically significant inhibition of yield was found at test concentrations of 7.9 mg/l and higher (Bonferroni t-test, α = 0.05).

Microscopic observations at the end of the test revealed a normal and healthy appearance of the exposed cells when compared to the control.

In the highest concentration few white particles were observed at the bottom of the vessel at the end of the test.
Results with reference substance (positive control):
- Results with reference substance valid? yes
- EC50: 1.0 mg/l with a 95% confidence interval ranging from 0.66 to 1.4 mg/l
Reported statistics and error estimates:
For determination of the NOEC and the EC50 the approaches recommended in the OECD guideline 201 were used. An effect was considered to be significant if statistical analysis of the data obtained for the test concentrations compared with those obtained in the negative control revealed significant reduction of growth rate or inhibition of yield (ANOVA, Tukey test, Bonferroni t-test, TOXSTAT Release 3.5, 1996, D.D. Gulley, A.M. Boelter, H.L. Bergman). Additionally, the EC10 was determined to meet the recommendations as put down in "A Review of Statistical Data Analysis and Experimental Design in OECD Aquatic Toxicology Test Guidelines" by S. Pack, August 1993.

Mean cell densities (x 104 cells/ml) during the final test

Initial conc.

LIN10001:4,4'-Isopropylidenediphenol, proxylated

(mg/l)

Exposure time (hours)

0

24

48

72

control

1.0

9.9

50.9

199.4

0.8

1.0

9.7

50.6

213.5

2.5

1.0

9.8

45.9

195.3

7.9

1.0

7.9

28.6

90.4

26

1.0

6.0

12.0

27.6

83

1.0

3.0

2.0

2.3

 

Percentage reduction of growth rate (total test period) and percentage inhibition of yield during the final test

Initial conc.

LIN10001:4,4'-Isopropylidenediphenol, proxylated

(mg/l)

Mean growth rate

Yield (0-72 h)

µ (0-72 h)

Reduction (%)

x104cells/ml

Inhibition (%)

control

0.07351

 

198.39

 

0.8

0.07449

-1.3

212.46

-7.1

2.5

0.07325

0.4

194.34

2.0

7.9

0.06254

14.9

89.36

55.0

26

0.04606

37.3

26.63

86.6

83

0.01169

84.1

1.33

99.3

 

Validity criteria fulfilled:
yes
Conclusions:
LIN10001:4,4’-Isopropylidenediphenol, propoxylated reduced growth rate and inhibited the yield of the fresh water algae species Pseudokirchneriella subcapitata significantly at 7.9 mg/l and higher.

The EC50 for growth rate reduction (ERC50: 0-72h) was 28 mg/l with a 95 % confidence interval ranging from 11 to 71 mg/l based on initially measured concentrations.

The EC50 for yield inhibition (EYC50: 0-72h) was 8.5 mg/l with a 95 % confidence interval ranging from 5.3 to 14 mg/l based on initially measured concentrations.

The NOEC for growth rate reduction and yield inhibition was 2.5 mg/l based on initially measured concentrations.
Endpoint:
toxicity to aquatic algae and cyanobacteria
Type of information:
experimental study
Adequacy of study:
supporting study
Study period:
2007
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:
Analysis performed at 0 and 72 hours
Vehicle:
no
Details on test solutions:
500 mg/L was mixed in water and filtered, with a maximum concentration of 64 mg/L
Concentrations tested were 4, 8, 16, 32 and 64 mg/L
Test organisms (species):
Desmodesmus subspicatus (previous name: Scenedesmus subspicatus)
Test type:
static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
72 h
Test temperature:
24 C, +/- 1 C
pH:
7.2 - 7.7
Nominal and measured concentrations:
Recovery of > 90%
Reference substance (positive control):
yes
Remarks:
Potassium dichromate
Key result
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
49 mg/L
Nominal / measured:
not specified
Conc. based on:
test mat.
Basis for effect:
growth rate
Duration:
72 h
Dose descriptor:
EC50
Effect conc.:
22 mg/L
Nominal / measured:
not specified
Conc. based on:
test mat.
Basis for effect:
other: yield

Basis for effect: Growth Rate NOEC = 8 mg/L and LOEC = 16 mg/L

Basis for effect: Yield NOEC = 8 mg/L and LOEC = 16 mg/L

Validity criteria fulfilled:
yes

Description of key information

The substance was found to be harmful to aquatic algae at the tested concentrations.

Key value for chemical safety assessment

EC50 for freshwater algae:
28 mg/L
EC10 or NOEC for freshwater algae:
5.1 mg/L

Additional information

Two studies were conducted to determine the toxicity of the substance to aquatic algae. Both studies were conducted in accordance with OECD Testing Guideline 201. The key study on BPA 2PO gave a 72 hour EC50 of 28 mg/L for growth rate, and a 72 hour EC10 of 5.1 mg/L, also for growth rate. The supporting study performed using BPA 5PO gave a 72 hour EC50 of 49 mg/L, also for growth rate.