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Toxicity to aquatic algae and cyanobacteria

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Endpoint:
toxicity to aquatic algae and cyanobacteria
Type of information:
experimental study
Adequacy of study:
key study
Study period:
29 April 2003 to 18 August 2003
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: Study performed in accordance with OECD & EU test guidelines in compliance with GLP.
Qualifier:
according to
Guideline:
OECD Guideline 201 (Alga, Growth Inhibition Test)
Deviations:
not specified
Qualifier:
according to
Guideline:
EU Method C.3 (Algal Inhibition test)
Deviations:
not specified
GLP compliance:
yes
Analytical monitoring:
yes
Details on sampling:
During the test duplicate samples for analysis were taken from the test concentration and the blank-control.
Frequency: at t=0 h, t=24 hand 72 h
Volume: 5ml
Storage: Samples were transferred to Analytical Chemistry directly after 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 and at the end of the test period.
Vehicle:
no
Details on test solutions:
The standard test procedures required generation of test solutions which contained completely dissolved test substance concentrations or stable and homogeneous mixtures or dispersions. The testing of concentrations that would disturb the test system were prevented as much as possible (e.g. film of the test substance on the water surface).
The batch of HATCOL 3331 tested was a clear colourless liquid with a purity of > 97.3% and the substance was not completely soluble in test medium at the concentration tested. The water solubility of Hatcol3331 at 20.3 ± 0.8°C was determined to be < 2.0x10E-4 g/I, according to the flask method (NOTOX Project 365052). The partition coefficient (n-octanol/water), Pow, was determined to be ≥ 5.1*10E6 (log Pow ≥ 6.7) at 20.3 ± 0.8°C (NOTOX Project 365085).
Preparation of test solutions started with a stock solution of 100 mg/l applying 2 days of magnetic stirring to ensure maximum solubility in test medium. The resulting solution was slightly hazy with a floating layer and test substance droplets. Collection of the water phase by siphoning or centrifugation was not an option considering the specific gravity of the test substance. After the stirring period the mixture was therefore filtered through a paper filter (ca. > 5 µm). The filtrate was very slightly hazy. Note that the medium for the blank-control received the same treatment.
After preparation, volumes of 50 ml were added to each replicate of the respective test concentration. Subsequently, adequate volumes of an algal suspension were added to each replicate providing a cell density of 10E4 cells/l
Test organisms (species):
Pseudokirchneriella subcapitata (previous names: Raphidocelis subcapitata, Selenastrum capricornutum)
Details on test organisms:
Species: Selenastrum capricornutum, strain: NIVA CHL 1.
Source: In-house laboratory culture
Reason for selection: This system is a unicellular algal species sensitive to toxic substances in the aquatic ecosystem and has been selected as an internationally accepted species.
Test type:
static
Water media type:
freshwater
Limit test:
yes
Total exposure duration:
72 h
Post exposure observation period:
No post exposure observation period specified in the study report.
Hardness:
Hardness (Ca+Mg) 0.24 mmol/I (24 mg CaCO3/l)
Test temperature:
The temperature of the test medium was 23.1°C at the start of the test. During the exposure period the temperature measured in the incubator was maintained between 23.2 and 23.9°C.
Hence, the temperature complied with the requirements as laid down in the protocol (21-25°C, constant within 2°C).
pH:
The pH values measured in the blank-control remained within the limits prescribed by the protocol (6.0-9.0, not varying more than 1.5 unit). However, the pH value measured in the test concentration at the end of the test was slightly higher than the highest limit described in the protocol. This was attributed to a relatively high increase in pH, which was caused by the high algal growth, and therefore not considered to have affected the test.
Dissolved oxygen:
Not specified in the study report.
Salinity:
Not applicable - freshwater study
Nominal and measured concentrations:
Measured test substance concentrations
Details on test conditions:
LIMIT TEST:
TEST CONCENTRATIONS
HATCOL 3331: A 5 µm filtrate prepared at a loading rate of 100 mg/I, the regulatory limit concentration.
Controls: Test medium without test substance or other additives (blank).
Replicates: 6 replicates of the test concentration and the blank control; 2 replicates of the test concentration without algae; 1 extra replicate of the test concentration and the blank-control for sampling purposes.

TEST PROCEDURE AND CONDITIONS
Test type: Static
Test vessels: 100 ml, all-glass
Medium: M2-medium
Cell density: An initial cell density of 1 x 10E4 cells/ml.
Test duration: 72 hours
Illumination: Continuously using TLD-lamps of the type 'Cool-white' of 30 Watt, with a light intensity within the range of 81-111 µE.mE-2.sE-1.
Incubation: During incubation the algal cells were kept in suspension by continuous shaking.

MEASUREMENTS
pH: At the beginning and at the end of the test. The pH of the solutions should preferably not deviate by more than 1.5 units during the test.
Temperature of medium: Continuously in a temperature-control vessel.

RECORDING OF CELL DENSITIES
At the beginning of the test, cells were counted by microscope, using a counting chamber.
Thereafter cell densities were determined by spectrophotometric measurement of samples at 720 nm using a Varian Cary 50 single beam spectrophotometer with immersion probe (pathlength =20 mm). Varian Nederland BV., Houten, The Netherlands. Algal medium was used as blank, and the extra replicate without algae was used as background for the treated solution.
After 24 hours of exposure, the test solutions were so turbid that they disturbed the spectrophotometric measurements. Although algal density was also measured spectrophotometrically after 24 hours, these data were only useful for the blank-controls.
Throughout the remainder of the test, algal density was counted by microscope.
Reference substance (positive control):
yes
Remarks:
potassium dichromate
Key result
Duration:
72 h
Dose descriptor:
NOEC
Effect conc.:
0.22 - 0.79 mg/L
Nominal / measured:
meas. (initial)
Conc. based on:
dissolved
Basis for effect:
growth rate
Details on results:
Measured test substance concentrations
The test substance consisted of a mixture of molecules with different molecular weights, which differed in water solubility, resulting in a number of peaks in the chromatogram of the test substance solutions. It was not possible to determine which molecule was responsible for the toxicological response, if any. Furthermore, since not all components were quantifiable in the calibration chromatograms, it was not possible to determine the concentration of the total test substance. Therefore, the toxicological evaluation was based on the water-soluble fraction at the loading rate. In addition, the actual concentration was estimated from the three largest peaks (peaks 1, 2 and 3) observed in the chromatograms of HA TCOL 3331.
The analytical results showed that the filtered solution prepared at a loading rate of 100 mg/I contained an initial concentration of 3.3 mg/l (based on peak 1), 4.1 mg/I (based on peak 2) or 4.2 mg/I (based on peak 3). After 24 hours of exposure the test concentration had decreased to below the limit of quantification of 0.2 mg/I (based on peak 1), 0.45 mg/l (based on peak 2) or 0.64 mg/I (based on peak 3). At the end of the test period the test concentration had decreased below the limit of quantification of 0.2 mg/I (based on peaks 1 and 2) or 0.40 mg/I (based on peak 3).
The average exposure concentration, based on peak 1, 2 or 3, respectively, was 0.22, 0.50 and 0.79 mg/l. Hence, average concentrations remained above or approximated the solubility limit of HATCOL 3331 (i.e. < 0.2 mg/I). The observed decrease was probably a consequence of this low solubility.

Mean cell densities
One replicate in the test group was considered to be an outlier, since it only showed a slight increase in cell density, while the other replicates in this group showed maximal growth. In fact, the cell density in the outlier was only 8% of the average value of the other replicates.

Inhibition of cell growth and reduction of growth rate
There was a small but insignificant effect on cell growth among algae exposed to the filtrate (Two-sample t-test, α=0.05). No significant differences were recorded between the values for growth rate in the filtrate (Two-sample t-test, α=0.05).

Experimental conditions
The pH values measured in the blank-control remained within the limits prescribed by the protocol (6.0-9.0, not varying more than 1.5 unit). However, the pH value measured in the test concentration at the end of the test was slightly higher than the highest limit described in the protocol. This was attributed to a relatively high increase in pH, which was caused by the high algal growth, and therefore not considered to have affected the test.
The temperature of the test medium was 23.1 °C at the start of the test. During the exposure period the temperature measured in the incubator was maintained between 23.2 and 23.9°C.
Hence, the temperature complied with the requirements as laid down in the protocol (21-25°C, constant within 2°C).

ACCEPTABILITY OF THE TEST
1. In the blank-control, cell density increased by an average factor of > 16 within 3 days.
2. The test conditions (pH, temperature) were maintained within the limits prescribed by the protocol, except for the pH value measured in the test concentration at the end of the test: this value was slightly higher than the highest limit described in the protocol. This was attributed to a relatively high increase in pH, which was caused by the high algal growth, and therefore not considered to have affected the test.
Results with reference substance (positive control):
The study procedures described in this report were based on the EEC Directive 92/69, Publication No. L383 Part C-3 adopted December, 1992; OECD guideline No. 201, Adopted June 7,1984; and ISO Standard 8692, First edition, 15 November 1989.
This reference test was carried out to check the sensitivity of the test system used by NOTOX to Potassium dichromate (Merck, Art. 4864, Batch K28974764).
Algae were exposed for a period of 72 hours to K2Cr2O7 concentrations of 0.18, 0.32, 0.56, 1.0, 1.8 and 3.2 mg/I and to a blank-control. The initial cell density was 1.0 x 10E4 cells/ml.

Results
Under the conditions of the reference study with Selenastrum capricornutum, potassium dichromate inhibited cell growth of this fresh water algae species at nominal concentrations of 0.56 mg/I and higher and reduced growth rate at 1.0 mg/I and higher.
The EC50 for cell growth inhibition (EBC50: 0-72h) was 0.73 mg/I with a 95 % confidence interval ranging from 0.45 to 1.2 mg/l. The historical ranges of the 72h EC50 for growth inhibition lie between 0.49 and 1.4 mg/l. Hence, the EBC50: 0-72h for the present batch corresponds with this range.
The EC50 for growth rate reduction (ERC50: 0-72h) was 1.2 mg/I with a 95 % confidence interval ranging from 0.90 to 1.6 mg/l. The historical ranges for growth rate reduction lie between 0.82 and 2.3 mg/l. Hence, the ERC50: 0-72h for the present batch corresponds with this range.
The protocol, raw data and report of this study are kept in the NOTOX archives. The test described above was performed under GLP conditions with a QA-check.
Reported statistics and error estimates:
Not specified in the study report.

Table 1: Mean cell densities during the limit test

Loading rate HATCOL 3331 (mg/l)

Exposure time (hours)

0

24

48

72

Blank control

1.0

4.8

37.9

149.2

100

1.0

6.9

31.9

124.6

 

Table 2: Percentage inhibition of cell growth during the limit test

Loading rate HATCOL 3331 (mg/l)

Cell growth (0-72 hrs)

Mean area (A)

Inhibition (%)

Blank control

2753.60

 

100

2364.00

14.1

 

Table 3: Percentage reduction of growth rate at different time intervals during the limit test

Loading rate HATCOL 3331 (mg/l)

Mean growth rate

µ (0-24 hrs)

Reduction (%)

µ (0.48 hrs)

Reduction (%)

µ (0-72 hrs)

Reduction (%)

Blank control

0.06510

 

0.07567

 

0.06943

 

100

0.07976

-22.5

0.071771

5.2

0.06694

3.6

 

Table 4: pH levels recorded during the study

Loading rate HATCOL 3331 (mg/l)

Exposure time (hours)

0

72

Blank control

8.4

9.0

100

7.8

9.2

 

 

Overview of % inhibition in cell growth and % reduction of growth rate in the reference test:

Concentration K2Cr2O7(mg/l)

Total cell growth:

Growth rate:

Mean Area

0-72h

Inhibition

%

Interval

 0-72h

Reduction

%

Blank-control

2273.92

 

0.06422

 

0.18

2185.2

3.9

0.06409

0.2

0.32

2299.84

-1.1

0.06558

-2.1

0.56

1443.54

36.5

0.05836

9.1

1.0

475.60

79.1

0.03771

41.3

1.8

169.96

92.5

0.01811

71.8

3.2

107.64

95.3

0.01207

81.2

 

Validity criteria fulfilled:
yes
Conclusions:
The NOEC for cell growth inhibition and growth rate reduction was 0.22-0.79 mg/I, obtained in a filtered solution at a loading rate of 100 mg/I the regulatory limit concentration.
Executive summary:

Selenastrum capricornutum, Fresh Water Algal Growth Inhibition Test with HATCOL 3331.

The study procedures described in this report were based on the EEC Directive 92/69, Publication No. L383 Part C-3 adopted December, 1992; OECD guideline No. 201, Adopted June 7,1984; and ISO Standard 8692, First edition, 15 November 1989.

The batch of HATCOL 3331 tested was a clear colourless liquid with a purity of 97.3% and the substance was not completely soluble in test medium at the concentration tested. The waters olubility of Hatcol 3331 at 20.3 ± 0.8°C was determined to be < 2.0x10E-4 g/I, according to the flask method (NOTOX Project 365052). The partition coeffcient (n-octanol/water), Pow, was determined to be ≥ 5.1*10E6 (log Pow ≥ 6.7) at 20.3 ± 0.8°C (NOTOX Project 365085).

Preparation of test solutions started with a stock solution of 100 mg/l applying 2 days of magnetic stirring to ensure maximum solubility in test medium. The resulting solution was slightly hazy with a floating layer and test substance droplets. Collection of the water phase by siphoning or centrifugation was not an option considering the specific gravity of the test substance. After the stirring period the mixture was therefore filtered through a paper filter(ca. > 5 µm). The filtrate was very slightly hazy.

A limit test was performed exposing exponentially growing algal cultures to a filtered (ca. 5µm) HATCOL 3331 solution prepared at a loading rate of 100 mg/I and a blank-control. The initialcell density was 10E4 cells/ml. The total test period was 72 hours. Samples for determination of actual exposure concentrations were taken at the start, after 24 hours of exposure and at theend of the test period.

Analysis of the samples showed that average exposure concentrations were at or above thesolubility limit of HATCOL 3331 (I.e. < 0.2 mg/l).

The study met the acceptability criteria prescribed by the protocol and was considered valid.

HATCOL 3331 induced no inhibition of cell growth or reduction of growth rate in Selenastrum capricornutum at the concentration obtained in a filtered solution prepared at a loading rate of 100 mg/l, corresponding to an average exposure concentration of 0.22-0.79 mg/I (NOEC).

Due to the very low solubility of HATCOL 3331 in water, concentration levels that might be toxic for algae could not be reached.

Endpoint:
toxicity to aquatic algae and cyanobacteria
Type of information:
experimental study
Adequacy of study:
key study
Study period:
14 to 17 October 2003
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: Study performed in accordance with OECD & EU test guidelines in compliance with GLP.
Qualifier:
according to
Guideline:
OECD Guideline 201 (Alga, Growth Inhibition Test)
Deviations:
not specified
Qualifier:
according to
Guideline:
EU Method C.3 (Algal Inhibition test)
Deviations:
not specified
GLP compliance:
yes
Analytical monitoring:
yes
Details on sampling:
During the final test duplicate samples were taken from all concentrations and the blank-control.
Frequency: at t=0 h, t=24 hand t=72 h
Volume: 5ml
Storage: Not applicable, samples were analysed on the day of 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 and the end of the test period.
Vehicle:
no
Details on test solutions:
The standard test procedures required generation of test solutions, which contained completely dissolved test substance concentrations or stable and homogeneous mixtures or dispersions.
The testing of concentrations that would disturb the test system were prevented as much as possible (e.g. film of the test substance on the water surface).
HATCOL 3344 is a clear colourless liquid with a purity of 96.9%. The water solubility of HATCOL 3344 at 20.0 ± 0.8°C was determined to be < 2.0x10E-4g/l (pH was 7.4) using the flask method (NOTOX Project 365535).
All test solutions with a loading rate at or above 1.0 mg/l were prepared separately (loading rates of 1.0, 10 and 100 mg/l). These supersaturated solutions were stirred for two days to reach maximum solubility. After the stirring period the 100 mg/l loading rate contained a test substance floating layer and test substance particles, the 10 mg/l loading rate contained test substance particles and the 1.0 mg/l loading rate was observed to be clear and colourless.
Collection of the water phase by siphoning or centrifugation was not an option considering the specific gravity of the test substance (see also NOTOX Project 365535). After the stirring period all three mixtures were therefore filtered through a paper filer (Schleicher and Schuell 604) to remove the larger undissolved test substance particles (ca. > 5µm). Finally a ten-fold dilution was prepared from the filtrate prepared at a loading rate of 1.0 mg/l and indicated as 0.1 mg/l.
All test solutions were clear and colourless.
After preparation, volumes of 50 ml were added to each replicate of the respective test concentration. Subsequently, adequate volumes of an algal suspension were added to each replicate providing a cell density of 10E4 cells/ml.
Test organisms (species):
Pseudokirchneriella subcapitata (previous names: Raphidocelis subcapitata, Selenastrum capricornutum)
Details on test organisms:
Species: Selenastrum capricomutum, 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.
Test type:
static
Water media type:
freshwater
Limit test:
yes
Total exposure duration:
72 h
Post exposure observation period:
No post exposure observation period specified in the study report.
Hardness:
No specified in the study report.
Test temperature:
The temperature of the test medium was 23.4 °C at the start of the test. During the exposure period the temperature measured in the temperature control vessel was maintained between 23.3 and 24.0 °C, and complied with the requirements as laid down in the protocol (21-25°C, constant within 2°C).
pH:
6.5 – 9.7
pH remained within the limits prescribed by the protocol (pH: 6.0-9.0, not varying by more than 1.5 unit). Exceptions were the blank-control and the lowest test concentration, which had a pH above 9.0 at the end of the test period. Since this deviation could be related to a relatively
Dissolved oxygen:
Not specified in the study report.
Salinity:
Not specified in the study report.
Nominal and measured concentrations:
The concentrations of HATCOL 3344 were determined by Gas Chromatography with mass spectrometric detection (GC-MS). The test substance consisted of a mixture of molecules with different molecular weights, which differed in water solubility, resulting in a number of peaks in the chromatogram of the test substance solutions. It was not possible to determine which molecule was responsible for the toxicological response, if any. Furthermore, since not all components were quantifiable in the calibration chromatograms, it was not possible to determine the concentration of the total test substance. Therefore, the toxicological evaluation was based on the water-soluble fraction at the loading rate. In addition, the actual concentration was estimated from the two largest peaks (peaks 1 and 2) observed in the chromatograms of HATCOL 3344.
The analytical results showed that the filtered solution prepared at a loading rate of 100 mg/l had an initial concentration of 0.65 mg/l (when based on peak 1) or was below the limit of quantification (i.e. below 0.1 mg/l, when based on peak 2). The filtered solution prepared at a loading rate of 10 mg/l had an initial concentration of 0.12 mg/l (when based on peak 1) or was below the limit of quantification (i.e. below 0.1 mg/l, when based on peak 2). After 24 and 72 hours of exposure both test concentrations had decreased below the limit of quantification (based on both peaks). The lower test concentrations were below the limit of quantification from the start of exposure (based on both peaks).
The average exposure concentration at a loading rate of 100 mg/l, based on peak 1, was 0.18 mg/l, while the average exposure concentration at a loading rate of 10 mgl1, based on peak 1, was 0.08 mg/l. Hence, the average exposure concentration at loading rates of 10 and 100 mg/l approximated the solubility limit of HATCOL 3344 (i.e. < 0.2 mg/l. The observed decrease was probably a consequence of this extremely low solubility.
Details on test conditions:
Test concentrations
HATCOL 3344: 5 µm filtered solutions prepared at loading rates of 1.0, 10 and 100 mg/l and a ten-fold dilution of the filtrate prepared at a loading rate of 1.0 mg/l.
Controls: Test medium without test substance or other additives (blank-control).
Replicates: 3 replicates of each test concentration. 6 replicates of the blank-control. 2 replicates of the highest concentration without algae. 1 replicate of the lower test concentrations without algae. 1 extra replicate of each solution for sampling purposes.

Test procedures and conditions
Test duration: 72 hours
Test type: Static
Test vessels: 100 ml, all-glass, containing 50 ml of test medium
Medium: M2
Cell density: An initial cell density of 1 x 10E4 cells/ml.
Illumination: Continuously using TLD-Iamps of the type 'Cool-white' of 30 Watt, with a light intensity within the range of 78 to 111 µE.mE-2.sE-1.
Incubation: During incubation the algal cells were kept in suspension by continuous shaking.

Measurements
pH: At the beginning and at the end of the test. The pH of the solutions should preferably not deviate by more than 1.5 units during the test.
Temperature of medium: Continuously in a temperature control vessel.

Recording of cell densities: At the beginning of the test, cells were counted by microscope, using a counting chamber.
Thereafter cell densities were determined by spectrophotometric measurement of samples at 720 nm using a Varian Cary 50 single beam spectrophotometer with immersion probe (pathlength =20 mm). Varian Nederland BV., Houten, The Netherlands. Algal medium was used as blank. In order to correct for turbidity one control, without algae, was measured for the 100 mg/l loading rate at each time interval and also for the 10 mg/l loading rate at the end of the test period.
Reference substance (positive control):
yes
Remarks:
Potassium dichromate
Key result
Duration:
72 h
Dose descriptor:
NOELR
Effect conc.:
0.1 mg/L
Nominal / measured:
meas. (initial)
Conc. based on:
test mat.
Basis for effect:
growth rate
Details on results:
Final test
Measured test substance concentrations: The concentrations of HATCOL 3344 were determined by Gas Chromatography with mass spectrometric detection (GC-MS). The test substance consisted of a mixture of molecules with different molecular weights, which differed in water solubility, resulting in a number of peaks in the chromatogram of the test substance solutions. It was not possible to determine which molecule was responsible for the toxicological response, if any. Furthermore, since not all components were quantifiable in the calibration chromatograms, it was not possible to determine the concentration of the total test substance. Therefore, the toxicological evaluation was based on the water-soluble fraction at the loading rate. In addition, the actual concentration was estimated from the two largest peaks (peaks 1 and 2) observed in the chromatograms of HATCOL 3344.
The analytical results showed that the filtered solution prepared at a loading rate of 100 mg/l had an initial concentration of 0.65 mg/l (when based on peak 1) or was below the limit of quantification (i.e. below 0.1 mg/l, when based on peak 2). The fitlered solution prepared at a loading rate of 10 mg/l had an initial concentration of 0.12 mg/l (when based on peak 1) or was below the limit of quantification (i.e. below 0.1 mg/l, when based on peak 2). After 24 and 72 hours of exposure both test concentrations had decreased below the limit of quantification (based on both peaks). The lower test concentrations were below the limit of quantification from the start of exposure (based on both peaks).
The average exposure concentration at a loading rate of 100 mg/l, based on peak 1, was 0.18 mg/l, while the average exposure concentration at a loading rate of 10 mg/l, based on peak 1, was 0.08 mg/l. Hence, the average exposure concentration at loading rates of 10 and 100 mg/l approximated the solubility limit of HATCOL 3344 (i.e. < 0.2 mg/l. The observed decrease was probably a consequence of this extremely low solubility.

Inhibition of cell growth and reduction of growth rate: Inhibition of cell growth was 25% at loading rates of 1.0 and 10 mg/l and increased to 87% at a loading rate of 100 mg/l. No inhibition of cell growth was observed at a loading rate of 0.1 mg/l. Statistically significant inhibition of cell growth was found at loading rates of 1.0 mg/l and higher (Tukey test, α = 0.05).
Growth rates were in the range of the controls at the loading rate of 0.1 mg/l during the 72-hour test period. Reduction of growth rate was ca. 6% at loading rates of 1.0 and 10 mg/l and increased to 43% at a loading rate of 100 mg/l. Statistically significant reduction of growth rate was found at loading rates of 1.0 mg/l and higher (Tukey test, α = 0.05).

Determination of effect concentrations: Since the effects at the filtered solutions prepared at loading rates of 1.0 and 10 mg/l were approximately the same, EC-values were based only on the results at the filtered solutions prepared at loading rates of 10 and 100 mg/l and have to be considered as indicative.

Experimental conditions: pH remained within the limits prescribed by the protocol (pH: 6.0-9.0, not varying by more than 1.5 unit). Exceptions were the blank-control and the lowest test concentration, which had a pH above 9.0 at the end of the test period. Since this deviation could be related to a relatively high rate of algal growth it was not considered to have affected the validity criteria of the test.
Note that the test substance appeared to have an effect on the pH of the M2-medium at the start of the test. However, during exposure pH increased in all vessels, indicating that the initial pH reduction did not affect growth to a large extent.
The temperature of the test medium was 23.4°C at the start of the test. During the exposure period the temperature measured in the temperature control vessel was maintained between 23.3 and 24.0°C, and complied with the requirements as laid down in the protocol (21-25°C, constant within 2°C).
Results with reference substance (positive control):
Selenastrum capriconutum, strain: NIVA CHL 1. Fresh water algal growth inhibition test with potassium dichromate (NOTOX Project 381869).
Algae were exposed for a period of 72 hours to K2Cr2O7(POTASSIUM DICHROMATE) concentrations of 0.18, 0.32, 0.56, 1.0, 1.8 and 3.2 mg/l and to a blank-control. The initial cell density was 1.0 x 104 cells/ml.
Results:
Overview of % inhibition in cell growth and % reduction of growth rate In the reference test:
Concentration Total cell growth: Growth rate:
K2Cr2O7 Mean Area Inhibition Interval Reduction
(mg/l) 0-72h % 0-72h %
Blank-control 2342.68 0.06742
0.18 2290.52 2.2 0.06740 0.0
0.32 2068.32 11.7 0.06584 2.4
0.56 1328.36 43.3 0.05953 11.7
1.0 328.48 86.0 0.03535 47.6
1.8 49.20 97.9 0.00000 100.0
3.2 24.08 99.0 0.00000 100.0

Under the conditions of the reference study with Selenastrum capricomutum, potassium dichromate inhibited cell growth and reduced growth rate of this fresh water algae species at nominal concentrations of 0.56 mg/l and higher.
The EC50 for cell growth inhibition (EBC50: 0-72h) was 0.59 mg/l with a 95 % confidence interval ranging from 0.38 to 0.92 mg/l. The ISO-Standard gives a range for the EC50 for cell growth inhibition from 0.20 to 0.75 mg/l based on 16 inter-laboratory tests. Hence, the EBC50: 0-72h for the present batch is within this range.
The EC50 for growth rate reduction (ERC50: 0-72h) was 0.89 mg/l with a 95 % confidence interval ranging from 0.56 to 1.4 mg/l. The ISO-Standard gives a range for the EC50 for cell growth inhibition from 0.60 to 1.03 mg/l based on 16 inter-laboratory tests. Hence, the ERC50: 0-72h for the present batch is within this range.
Reported statistics and error estimates:
Not specified in the study report

Table 1 Mean cell densities (x 104cells/ml) during the final test

Loading rate Hatcol 3344 (mg/l)

Exposure time (hours)

0

24

48

72

Blank-control

1.0

5.5

41.0

174.7

0.1

1.0

5.6

43.9

171.5

1.0

1.0

5.1

31.1

129.7

10

1.0

5.9

33.0

124.2

100

1.0

2.7

7.8

19.0

 

Table 2 Percentage inhibition of cell growth during the final test

Loading rate Hatcol 3344 (mg/l)

Cell growth (0-72hrs)

Mean area (A)

Inhibition (%)

Blank-control

3153.98

 

0.1

3187.60

-1.1

1.0

2364.48

25.0

10

2364.64

25.0

100

420.68

86.7

 

Table 3 Percentage reduction of growth rate at different time intervals during the final test

Loading rate Hatcol 3344 (mg/l)

Mean growth rate

µ (0-24 hrs)

Reduction (%)

µ (0-48 hrs)

Reduction (%)

µ (0-72 hrs)

Reduction (%)

Blank-control

0.07110

 

0.07728

 

0.07168

 

0.1

0.07197

-1.2

0.07881

-2.0

0.07138

0.4

1.0

0.06772

4.7

0.07159

7.4

0.06752

5.8

10

0.07376

-3.7

0.07283

5.7

0.06697

6.6

100

0.04162

41.5

0.04264

44.8

0.04091

42.9

 

Table 4 Effect parameters

Parameter

Loading rate HATCOL 3344 (mg/l)

95%-confidence Interval

Observed NOELR

0.1

 

72h EBL10

*

*

72h EBL50

25

19-35

72h ERL10

12

10-15

72h ERL50

>100

 

*Could not be calculated using log-linear regression

 

Table 5 pH levels recorded during the final test

Loading rate Hatcol 3344 (mg/l)

Exposure time (hours)

0

72

Blank-control

8.4

9.5

0.1

8.3

9.7

1

8.1

8.8

10

7.8

8.6

100

6.5

7.8

 

Validity criteria fulfilled:
yes
Conclusions:
The EL50 for cell growth inhibition (EBL50: 0-72h) was 25 mg/l with a 95 % confidence interval ranging from 19 to 35 mg/l.
The EL50 for cell growth inhibition (EBL10: 0-72h) could not be determined using log-linear regression.
As growth rate is derived from the slope under the growth curve in a logarithmic plot, the measure of the specific growth rate is preferable over biomass following from the mathematical nature of exponential growth.
The EL50 for growth rate reduction (ERL50: 0-72h) was beyond the range tested.
The EL10 for growth rate reduction (ERL10: 0-72h) was 12 mg/l with a 95 % confidence interval ranging from 10 to 15 mg/l.
The NOELR for both cell growth inhibition and growth rate reduction was 0.1 mg/l.
Executive summary:

Selenastrum capricorutum. Fresh Water Algal Growth Inhibition Test with HATCOL 3344.

The study procedures described in this report were based on the ISO International Standard8692, 1989. In addition, the procedures were designed to meet the test methods and validitycriteria of the EEC directive 92169. Part C.3, 1992 and the OECD guideline No. 201, 1984.

HATCOL 3344 is a clear colourless liquid with a purity of 96.9%. The water solubility of HATCOL 3344 at 20.0 ± 0.8°C was determined to be < 2.0x10e-4 g/l (pH was 7.4) using the flask method (NOTOX Project 365535).

All test solutions with a loading rate at or above 1.0 mg/l were prepared separately (loadingrates of 1.0, 10 and 100 mg/I). These supersaturated solutions were stirred for two days toreach maximum solubility. Collection of the water phase by siphoning or centrifugation was not an option considering the specific gravity of the test substance (see also NOTOX Project 365535). After the stirring period all three mixtures were therefore filtered through a paper filter (Schleicher and Schuell 604, ca. > 5µm). Finally a ten-fold dilution was prepared from the filtrate prepared at a loading rate of 1.0 mg/l. All test solutions were clear and colourless.

A final test was performed exposing exponentially growing algae to 5 µm filtered solutions prepared at loading rates of 1.0, 10 and 100 mg/l and in addition to a ten-fold dilution of the filtrate prepared at a loading rate of 1.0 mg/l for a period of 72 hours. Samples for analytical confirmation of actual exposure concentrations were taken from all test solutions at the start, after 24 hours of exposure and at the end of the test.

Analysis of the samples showed that the average exposure concentration in the WAFs prepared at loading rates of 10 and 100 mg/l approximated the solubility limit of HATCOL 3344 (i.e. < 0.2 mg/l). However, since not all components were quantifiable in the calibration chromatograms, it was not possible to determine the concentration of the total test substance. Therefore, the toxicological evaluation was based on loading rates.

In the controls, cell density increased by an average factor of > 16 within 3 days. Temperature and pH remained within the ranges prescribed by the protocol, except for the pH of the blank-control and the lowest test concentration, which increased above 9.0 at the end of the test period. Since this deviation could be related to a relatively high rate of algal growth it was not considered to have affected the validity criteria of the test.

Due to the fact that test concentrations below or approximating the water solubility level of HATCOL 5236 could not be analysed as these were below the limit of quantification, a different approach was followed for the calculation of EC and NOEC-values.

To this respect the following text quoted from the OECD guidance on classification of chemicals is applicable: 'Many substances covered by the classification scheme are in fact mixtures, for which measurement of exposure concentrations is difficult, and in some cases impossible.

Substances such as petroleum distillate fractions, polymers, substances with significant levels of impurities, etc can pose special problems since the toxic concentration is difficult to define and impossible to verify. Typical testing procedures often rely on the formation of a Water Soluble Fraction WSF) or Water Accommodated Fraction WAF) and data are reported in termsof loading rates. These data may be used in applying the classification criteria.' (Organization for Economic Co-operation and Development (OECO), OECO guidance document on the use of the harmonised system for the classification of chemicals which are hazardous for the aquatic environment, OECD series on testing and assessment number 27, July 23,2001).

HATCOL 3344 reduced growth rate of Selenastrum capricornutum significantly at loading rates of 1.0 mg/l and higher.

The Table below gives the effect parameters based on loading rates.

Parameter

Loading rate HATCOL 3344 (mg/l)

95%-confidence Interval

Observed NOELR

0.1

 

72h-EBL10

*

*

72h-EBL0

25

19-35

72h ERL10

12

10-15

72h ERL50

>100

 

*Could not be calculated using log-linear regression.

As growth rate is derived from the slope under the growth curve in a logarithmic plot, the measure of the specific growth rate is preferable over biomass following from the mathematical nature of exponential growth.

Endpoint:
toxicity to aquatic algae and cyanobacteria
Type of information:
experimental study
Adequacy of study:
key study
Study period:
06 May 2003 to 13 October 2003
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: Study performed in accordance with OECD & EU test guidelines in compliance with GLP.
Qualifier:
according to
Guideline:
OECD Guideline 201 (Alga, Growth Inhibition Test)
Deviations:
not specified
Qualifier:
according to
Guideline:
EU Method C.3 (Algal Inhibition test)
Deviations:
not specified
GLP compliance:
yes
Analytical monitoring:
yes
Details on sampling:
During the final test duplicate samples were taken from all concentrations and the blank-control.
Frequency: at t=0 h and t=72 h
Volume: 5ml
Storage: Not applicable, samples were analysed on the day of 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 and the end of the test period.
Vehicle:
no
Details on test solutions:
The standard test procedures required generation of test solutions which contained completely dissolved test substance concentrations or stable and homogeneous mixtures or dispersions.
The testing of concentrations that would disturb the test system were prevented as much as possible (e.g. film of the test substance on the water surface).
HATCOL 5236 is a clear pale yellow liquid with a purity of 97.6%. The water solubility of
HATCOL 5236 at 20.0 ± 0.8°C was determined to be < 2.0x10e-4 g/l using the flask method (NOTOX Project 365041 ).
All test solutions with a loading rate at or above 1.0 mg/l were prepared separately. These supersaturated solutions were stirred for two days to reach maximum solubility. After the stirring period the mixtures contained a test substance floating layer and test substance particles.
Collection of the water phase by siphoning or centrifugation was not an option considering the specific gravity of the test substance {see also NOTOX Project 365041 ). After the stirring period the mixtures were therefore filtered through a paper filter (Schleicher and Schuell 604) to remove the larger undissolved test substance particles (ca.> 5 µm). Finally a ten-fold dilution was prepared from the filtrate prepared at a loading rate of 1.0 mg/l and indicated as 0.1 mg/l.
All test solutions were clear and colourless, except for the two highest test concentrations, which were very slight to slightly hazy/cloudy, respectively. Note that the blank-control received the same treatment. After preparation, volumes of 50 ml were added to each replicate of the respective test concentration. Subsequently, adequate volumes of an algal suspension were added to each replicate providing a cell density of 10e4 cells/ml.
Test organisms (species):
Pseudokirchneriella subcapitata (previous names: Raphidocelis subcapitata, Selenastrum capricornutum)
Details on test organisms:
Species: Selenastrum caprtcomutum, 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.

Stock culture: Algae stock cultures were started by inoculating growth medium with algal cells from a pure culture on agar. The suspensions were continuously aerated and exposed to light in a climate room at a temperature of 23±2°C.
Light intensity: 60 to 120 µE/m2/s when measured in the photosynthetically effective wavelength range of 400 to 700 nm.

Stock culture medium: M1; formulated using Milli-Ro water (tap-water purified by reverse osmosis; Millipore Corp., Bedford, Mass., USA) with the following composition:
NaNO3 500 mg/l
K2HPO4 40 mg/l
MgSO4•7H2O 76 mg/l
Na2CO3•10H2O 54 mg/l
C6H8O7•H2O 6 mg/l
NH4NO3 330 mg/l
CaCl2•H2O 36 mg/l
C8H5FeO7•xH2O 6 mg/l
H3BO3 2.9 mg/l
MnCl2•4H2O 1.81 mg/l
ZnCl2 0.11 mg/l
CUSO4•5H2O 0.08 mg/l
(NH4)5Mo7O24•4H2O 0.018 mg/l

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 2.104 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 180-Standard "Algal growth inhibition test" Nov. 1989; 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 80 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 (254 mg CaCO3/l)
pH 8.3 ± 0.2
Test type:
static
Water media type:
freshwater
Limit test:
yes
Total exposure duration:
72 h
Post exposure observation period:
No post exposure observation period specified in the study report.
Hardness:
Hardness (Ca+Mg) 0.24 mmol/l (254 mg CaCO3/l)
Test temperature:
The temperature of the test medium was 23.4°C at the start of the test. During the exposure period the temperature measured in the temperature control vessel was maintained between 22.1 and 22.9°C, and complied with the requirements as laid down in the protocol (21-25°C, constant within 2°C).
pH:
pH: 6.0-9.0, not varying by more than 1 unit.
Dissolved oxygen:
No specified in the study report.
Salinity:
No specified in the study report.
Nominal and measured concentrations:
Measured test substance concentrations
The concentrations of HATCOL 5236 were determined by Gas Chromatography with mass spectrometric detection (GC-MS). The test substance consisted of a mixture of molecules with different molecular weights, which differed in water solubility, resulting in a number of peaks in the chromatogram of the test substance solutions. It was not possible to determine which molecule was responsible for the toxicological response, if any. Furthermore, since not all components were quantifiable in the calibration chromatograms, it was not possible to determine the concentration of the total test substance. Therefore, the toxicological evaluation was based on the water-soluble fraction at the loading rate. In addition, the actual concentration was estimated from the two largest peaks (peaks 1 and 2) observed in the chromatograms of HATCOL 5236.
The analytical results showed that the filtered solution prepared at a loading rate of 100 mg/l had an initial concentration of 1.4 mg/l (when based on peak 1) or 0.34 mg/l (when based on peak 2). After 72 hours of exposure the test concentration had decreased below the limit of quantification (i.e. below 0.1 mg/l, based on both peaks). The lower test concentrations were below the limit of quantification from the start of exposure (based on both peaks).
The average exposure concentration at a loading rate of 100 mg/l, based on peak 1, was 0.27 mg/l, while the average exposure concentration, based on peak 2, was 0.13 mg/l. Hence, the average exposure concentration at a loading rate of 100 mg/l remained above or approximated the solubility limit of HATCOL 5236 (i.e. < 0.2 mg/l). The observed decrease was probably a consequence of this extremely low solubility. Since toxicologically relevant test concentrations could not be analysed, biological results were based on loading rates.
Details on test conditions:
TEST CONCENTRATIONS
HATCOL 5236: 5 µm filtered solutions prepared at loading rates of 1.0, 10 and 100 mg/l and a ten-fold dilution of the filtrate prepared at a loading rate of 1.0 mg/l.
Controls: Test medium without test substance or other additives (blank-control).
Replicates: 3 replicates of each test concentration. 6 replicates of the blank-control. 2 replicates of the highest concentration without algae. 1 replicate of the lower test concentrations without algae.

TEST PROCEDURE AND CONDITIONS
Test type: Static
Test vessels: 100 ml, all-glass
Medium: M2
Cell density: An initial cell density of 1 x 104 cells/ml.
Test duration: 72 hours
Illumination: Continuously using TLD-lamps of the type 'Cool-white' of 30 Watt, with a light Intensity within the range of 76 to 105 µE.m-2.s-1
Incubation: 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:
NOELR
Effect conc.:
0.1 mg/L
Nominal / measured:
meas. (initial)
Conc. based on:
test mat.
Basis for effect:
growth rate
Key result
Duration:
72 h
Dose descriptor:
NOELR
Effect conc.:
0.1 mg/L
Nominal / measured:
meas. (initial)
Conc. based on:
test mat.
Basis for effect:
biomass
Details on results:
Inhibition of cell growth and reduction of growth rate: Inhibition of cell growth increased with increasing loading rates of HATCOL 5236 from 1.0 mg/l upwards resulting in 93% inhibition at a loading rate of 100 mg/l. Statistically significant inhibition of cell growth was found at loading rates of 1 a mg/l and higher (Tukey test: a=0.05).
Growth rates of algae exposed to loading rates of 1 0 mg/l and higher were increasingly reduced. Statistically significant reduction of growth rate was found at loading rates of 10 mg/l and higher (Tukey test: 0=0.05).
HATCOL 5236 is a mixture of pentaerythritol-bound fatty acids with each molecule containing four chains of fatty acids with various length. Fatty acids can be absorbed by algae and possibly even be metabolised. At the lowest test concentration algal cells had significantly grown during the test period when compared to the blank-control..
The 'roughly' filtered solutions prepared at loading rates of 10 and 100 mg/l were emulsions of micro-scale droplets. The presence of these droplets could have influenced algal cells causing inhibition of cell growth.

Experimental conditions: pH remained within the limits prescribed by the protocol (pH: 6.0-9.0, not varying by more than 1 unit). Note that the test substance appeared to have an effect on the pH of the M2-medium at the start of the test. However, during exposure this effect was straightened out.
The temperature of the test medium was 23.4°C at the start of the test. During the exposure period the temperature measured in the temperature control vessel was maintained between 22.1 and 22.9°C, and complied with the requirements as laid down in the protocol (21-25°C, constant within 2°C).

The EL50 for total cell growth inhibition (EBL50: 0-72h) was 8.0 mg/l with a 95% confidence interval ranging from 3.5 to 19 mg/l.
The EL10 for total cell growth Inhibition (EBL10: 0-72h) was 0.71 mg/l with a 95% confidence interval ranging from 0.28 to 1.80 mg/l.
As growth rate is derived from the slope under the growth curve in a logarithmic plot, the measure of the specific growth rate is preferable over biomass following from the mathematical nature of exponential growth. In addition total cell growth is depended on growth rate, whereas growth rate is independent from cell density during exponential cell growth as was the case in the present test for all concentrations. For evaluation of the results and for classification of the test substance it is therefore advised to use growth rate rather than total cell growth.
The EL50 for growth rate reduction (ERL50: 0-72h) was 47 mg/l with a 95% confidence interval ranging from 9.9 to 230 mg/l.
The EL10 for growth rate reduction (ERL10: 0-72h) was 2.0 mg/l with a 95% confidence interval ranging from 0.41 to 9.6 mg/l.
The NOELR for both cell growth inhibition and growth rate reduction was 1.0 mg/l.
Results with reference substance (positive control):
This reference test was carried out to check the sensitivity of the test system used by NOTOX to Potassium dichromate (Merck, Art. 4864, Batch K28974764).
Algae were exposed for a period of 72 hours to K2Cr20 7 concentrations of 0.18, 0.32, 0.56, 1.0, 1.8 and 3.2 mg/l and to a blank-control. The initial cell density was 1.0 x 104 cells/ml.
Under the conditions of the reference study with Selenastrum capricomutum, potassium dichromate inhibited cell growth of this fresh water algae species at nominal concentrations of 0.56 mg/l and higher and reduced growth rate at 1.0 mg/l and higher.
The EC50 for cell growth inhibition (ERC50: 0-72h) was 0.73 mg/l with a 95% confidence interval ranging from 0.45 to 1.2 mg/l. The historical ranges of the 72h EC50 for growth inhibition lie between 0.49 and 1.4 mg/l. Hence, the ERC50: 0-72h for the present batch corresponds with this range.
The EC50 for growth rate reduction (ERC50: 0-72h) was 1.2 mg/l with a 95% confidence interval ranging from 0.90 to 1.6 mg/l. The historical ranges for growth rate reduction lie between 0.82 and 2.3 mg/l. Hence, the ERC50: 0-72h for the present batch corresponds with this range.
Reported statistics and error estimates:
ACCEPTABILITY OF THE TEST
1. In the controls, cell density increased by an average factor of > 16 within 3 days.
2. Further, test conditions (temperature and pH) remained within the ranges prescribed by the protocol.
DETERMINATION OF EL-VALUES
The EL-values with respective 95% confidence intervals have been calculated from growth inhibition and growth rate reduction versus the log of the loading rate curves.

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

Loading rate Hatcol 5236 (mg/l)

Exposure time (hours)

0

24

48

72

Blank-control

1.0

2.7

12.5

45.4

0.10

1.0

3.6

20.8

81.8

1.0

1.0

3.7

10.1

36.0

10

1.0

2.4

7.6

20.2

100

1.0

1.3

1.7

3.9

 

Percentage inhibition of cell growth during the final test

Loading rate Hatcol 5236 (mg/l)

Cell growth (0-72 hrs)

Mean area (A)

Inhibition (%)

Blank control

849.28

 

0.10

1507.28

-77.5

1.0

702.80

17.2

10

421.76

50.3

100

59.76

93.0

 

Percentage reduction of growth rate at different time intervals during the final test

Loading rate Hatcol 5236 (mg/l)

Mean growth rate

µ (0-24 hrs)

Reduction (%)

µ (0-48 hrs)

Reduction (%)

µ (0-72 hrs)

Reduction (%)

Blank control

0.04045

 

0.05251

 

0.05285

 

0.10

0.05360

-32.5

0.06320

-20.3

0.06115

-15.7

1.0

0.05404

-33.6

0.04811

8.4

0.04971

5.9

10

0.03616

10.6

0.04224

19.6

0.04168

21.1

100

0.00980

75.8

0.01125

78.6

0.01903

64.0

 

pH levels recorded during the final study

Loading rate Hatcol 5236 (mg/l)

Exposure time (hours)

0

72

Blank control

8.2

8.0

0.10

8.2

8.8

1.0

8.1

7.9

10

7.1

7.7

100

6.5

7.4

 

EL-values for growth inhibition

Loading rate

X

Y

Slope:

37.8580

 

(mg/l)

Log conc. (mg/l)

Inhibition (%)

Intercept:

15.6588

0.10

*

-81.1

Multiple R:

0.9874

0.10

*

84.8

n = number of observations:

9

0.10

*

-66.5

 

1.0

0.000

7.9

Regression line: Y = 37.86X + 15.56

 

1.0

0.000

22.8

 

1.0

0.000

21.0

Prediction of X values based in known Y values

10

1.000

54.4

Known Y Inhibition (%)

10Xreg(mg/l)

10X95% -(mg/l)

10X95%+(mg/l)

10

1.000

50.6

10

1.000

46.0

10

0.71

0.28

1.80

100

2.000

95.0

25

1.76

0.73

4.28

100

2.000

92.4

50

8.07

3.45

18.91

100

2.000

91.5

100

168.98

65.88

433.44

*Not included in the calculations

 

EL-values for growth rate reduction

Loading rate

X

Y

Slope:

29.0289

 

(mg/l)

Log conc. (mg/l)

Inhibition (%)

Intercept:

1.3333

0.10

*

-16.8

Multiple R:

0.9614

0.10

*

-16.7

n = number of observations:

9

0.10

*

-13.6

 

1.0

0.000

2.9

Regression line: Y = 29.03X + 1.33

 

1.0

0.000

8.1

 

1.0

0.000

6.8

Prediction of X values based in known Y values

10

1.000

23.8

Known Y Inhibition (%)

10Xreg(mg/l)

10X95% -(mg/l)

10X95%+(mg/l)

10

1.000

20.4

10

1.000

19.3

10

1.99

0.41

9.61

100

2.000

65.9

25

6.54

1.42

30.00

100

2.000

63.4

50

47.48

9.87

228.49

100

2.000

62.7

 

 

 

 

*Not included in the calculations

 

Overview of % inhibition in cell growth and % reduction of growth rate in the reference test

Concentration K2Cr2O7(mg/l)

Total cell growth:

Growth rate:

Mean area

Inhibition

Interval

Reduction

0-72h

%

0-72h

%

Blank-control

2273.92

 

0.06422

 

0.18

2185.92

3.9

0.06409

0.2

0.32

2299.84

-1.1

0.06558

-2.1

0.56

1443.54

36.5

0.05836

9.1

1.0

475.60

79.1

0.03771

41.3

1.8

169.96

92.5

0.01811

71.8

3.2

107.64

95.3

0.01207

81.2

 

Validity criteria fulfilled:
yes
Conclusions:
The EL50 for total cell growth inhibition (EBL50: 0-72h) was 8.0 mg/l with a 95% confidence interval ranging from 3.5 to 19 mg/l.
The EL10 for total cell growth Inhibition (EBL10: 0-72h) was 0.71 mg/l with a 95% confidence interval ranging from 0.28 to 1.80 mg/l.
The EL50 for growth rate reduction (ERL50: 0-72h) was 47 mg/l with a 95% confidence interval ranging from 9.9 to 230 mg/l.
The EL10 for growth rate reduction (ERL10: 0-72h) was 2.0 mg/l with a 95% confidence interval ranging from 0.41 to 9.6 mg/l.
The NOELR for both cell growth inhibition and growth rate reduction was 1.0 mg/l.
Executive summary:

Selenastrum capricomutum, Fresh Water Algal Growth Inhibition Test with HATCOL 5236.

 

The study procedures described in this report were based on the ISO International Standard 6341, 1996. In addition, the procedures were designed to meet the test methods and validity criteria of the EEC directive 92/69, Part C.3, 1992 and the OECD guideline No. 201 Part I, 1984.

 

HATCOL 5236 is a clear pale yellow liquid with a purity of 97.6%. The water solubility of HATCOL 5236 at 20.0± 0.8°C was determined to be< 2.0x10 -4g/l using the flask method (NOTOX Project 365041).

 

All test solutions with a loading rate at or above 1.0 mg/l were prepared separately. These supersaturated solutions were stirred for two days to reach maximum solubility. After the stirring period the mixtures contained a test substance floating layer and test substance particles. Collection of the water phase by siphoning or centrifugation was not an option considering the specific gravity of the test substance. After the stirring period the mixtures were therefore filtered through a paper filter (ca.> 5 µm). In addition a ten-fold dilution was prepared from the filtrate prepared at a loading rate of 1.0mg/l. All test solutions were clear and colourless, except for the two highest test concentrations, which were very slight to slightly hazy, respectively.

 

A final test was performed exposing exponentially growing algae to 5µm filtered solutions prepared at loading rates of 1.0, 10 and 100mg/l and a ten-fold dilution of the filtrate prepared at a loading rate of 1.0 mg/l for a period of 72 hours. Samples for analytical confirmation of actual exposure concentrations were taken from all test solutions at the start and at the end of the test.

 

Analysis of the samples showed that the average exposure concentration in the WAF prepared at a loading rate of 100mg/l was at above or approximated the solubility limit of HATCOL 5236 (i.e.<0.2 mg/l). Since toxicological relevant test concentrations could not be analysed, biological results were based on loading rates.

 

The study met the acceptability criteria prescribed by the protocol and was considered valid.

 

Due to the fact that test concentrations below or approximating the water solubility level of HATCOL 5236 could not be analysed as these were below the limit of quantification, a different approach was followed for the calculation of EC and NOEC-values.

To this respect the following text quoted from the OECD guidance on classification of chemicals is applicable: 'Many substances covered by the classification scheme are in fact mixtures, for which measurement of exposure concentrations is difficult, and in some cases impossible. Substances such as petroleum distillate fractions, polymers, substances with significant levels of impurities, etc can pose special problems since the toxic concentration is difficult to define and impossible to verify. Typical testing procedures often rely on the formation of a Water Soluble Fraction (WSF) or Water Accommodated Fraction (WAF) and data are reported in terms of loading rates. These data may be used in applying the classification criteria.' (Organization for Economic Co-operation and Development (OECD), OECD guidance document on the use of the harmonised system for the classification of chemicals which are hazardous for the aquatic environment, OECD series on testing and assessment number 27, July 23, 2001).

 

HATCOL 5236 reduced growth rate of Sefenastrum capricamutum significantly at loading rates of 10 mg/l and higher.

The EL50 for total cell growth inhibition (EBL50:0·72h) was 8.0 mg/l with a 95% confidenceinterval ranging from 3.5 to 19 mg/l.

The EL10 for total cell growth inhibition (EBL10:0·72h) was 0.71 mg/l with a 95% confidence interval ranging from 0.28 to 1.80 mg/l.

 

As growth rate is derived from the slope under the growth curve in a logarithmic plot, themeasure of the specific growth rate is preferable over biomass following from the mathematical nature of exponential growth. In addition total cell growth is depended on growth rate, whereasgrowth rate is independent from cell density during exponential cell growth as was the case inthe present test for all concentrations. For evaluation of the results and for classification of thetest substance it is therefore advised to use growth rate rather than total cell growth.

 

The EL50 for growth rate reduction (ERL50:0-72h) was 47 mg/l with a 95% confidence interval ranging from 9.9 to 230 mg/l.

The EL10 for growth rate reduction (ERL10:0-72h) was 2.0 mg/l with a 95% confidence interval ranging from 0.41 to 9.6 mg/l.

 

The NOELR for both cell growth inhibition and growth rate reduction was 1.0 mg/l.

Endpoint:
toxicity to aquatic algae and cyanobacteria
Type of information:
experimental study
Adequacy of study:
supporting study
Study period:
25 - 28 Oct 2005
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: GLP-Guideline study with acceptable restrictions
Qualifier:
equivalent or similar to
Guideline:
OECD Guideline 201 (Alga, Growth Inhibition Test)
GLP compliance:
yes
Specific details on test material used for the study:
Details on properties of test surrogate or analogue material (migrated information):PHYSICO-CHEMICAL PROPERTIES- Water solubility (under test conditions): Insoluble
Analytical monitoring:
no
Vehicle:
no
Details on test solutions:
PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)- Method: Water Accommodated Fraction (WAF): A nominal 1000 mg/L stock solution was prepared in culture medium by the WAF method. The stock solution was prepared by stirring the test material in dilution water for 20 hours, followed by settling for 4 hours. The aqueous layer was then removed for testing. The test solutions were prepared by adding the 1000 mg/L stock solution to culture medium water in appropriate quantities to obtain the desired concentrations for the test.
Test organisms (species):
Pseudokirchneriella subcapitata (previous names: Raphidocelis subcapitata, Selenastrum capricornutum)
Details on test organisms:
TEST ORGANISM- Strain: CCAP 278/4- Source (laboratory, culture collection): Culture Collection of Algae and Protozoa, Institute of Freshwater Ecology, Windermere Laboratory- Age of inoculum (at test initiation): Pre-culture growing in exponential phase- Method of cultivation: Temperature: 23 ± 2 °C, Illumination: 6000 - 10000 lux continuous white light, shaking: 200 rpm, culture medium: according to OECD giudelines. Sterile nutrient stock solution were prepared and added to the dilution water to obtain the culture medium.
Test type:
static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
72 h
Test temperature:
test start: 22.5test end: 21.5
pH:
test start: 7.4 - 7.6test end: 7.2 - 7.3
Nominal and measured concentrations:
Nominal: 0, 100, 180, 320, 560, 1000 mg/L
Details on test conditions:
TEST SYSTEM- Test vessel: - Material, size, headspace, fill volume: 250 mL conical flasks filled with 100 mL test medium- Initial cells density: 10000 cells/mL- Control end cells density: 153.89 x 10 exp 4 cells/mL- No. of vessels per concentration (replicates): 3- No. of vessels per control (replicates): 6TEST MEDIUM / WATER PARAMETERS- Source/preparation of dilution water: Deionised water sterilised by autoclaving at 120°C for 30 minutes- Culture medium different from test medium: No- Intervals of water quality measurement: The pH and temperature were measured on the pooled replicates for each test and control solution immediately prior to initiating the test and at the end of the full 72 hour test period. OTHER TEST CONDITIONS- Sterile test conditions: yes- Adjustment of pH: Yes, to 8.0 ± 0.2- Photoperiod: Continuous light- Light intensity and quality: 6000 - 10000 lux white lightEFFECT PARAMETERS MEASURED (with observation intervals if applicable) : - Determination of cell concentrations: The cell density was determined at 24, 48 and 72 hours on a small volume removed from each replicate flask. The cell counts were made using a haemocytometer and microscope. TEST CONCENTRATIONS- Range finding study - Test concentrations: 1000 mg/L - Results used to determine the conditions for the definitive study: EC50 as being approx. 1000 mg/L.
Reference substance (positive control):
no
Key result
Duration:
72 h
Dose descriptor:
EL50
Effect conc.:
> 1 000 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth rate
Remarks on result:
other: WAF loading rate
Key result
Duration:
72 h
Dose descriptor:
EL10
Effect conc.:
> 1 000 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth rate
Remarks on result:
other: WAF loading rate
Key result
Duration:
72 h
Dose descriptor:
EL50
Effect conc.:
> 1 000 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
biomass
Remarks on result:
other: WAF loading rate
Details on results:
- Exponential growth in the control (for algal test): Yes
Reported statistics and error estimates:
The inhibition of growth was calculated using both the biomass integral (area under the growth curve) and the growth rate method.The EL50 values were estimated where possible using a logarithm-linear or logarithm-probit plot of concentration and percent growth inhibition.

The test substance showed to be of low toxicity to Pseudokirchneriella subcapitata. The inhibiton for the WAF loading rate of 1000 mg/L after 72h by biomass integral was 18% and by growth rate 2%. Therefore, the 72 hour EL50 was estimated as > 1000 mg/L using the biomass integral and also by growth rate calculation. Because of the serial dilution from the highest concentration (1000 mg/L), only the 1000 mg/L test concentration was valid and could be used for evaluation of toxicity of the test substance. Without chemical analytics of the diluted concentrations, no information about the exact test concentration could be stated.

Table 1: Cell density measurements (Mean initial cell density: 1 x 10 exp 4 cells/ml)

Concentration [mg/L]

Replicate No.

Cell density measurements [cells/mL x 10 exp 4]

24 hours

48 hours

72 hours

0

1

2

3

4

5

6

3.00

2.67

2.67

2.33

1.67

2.00

37.00

30.33

27.33

41.33

28.00

33.67

149.33

157.33

150.67

148.67

168.00

149.33

Mean

2.39

32.94

153.89

100

1

2

3

2.00

3.33

3.67

42.67

47.00

38.33

166.67

165.33

140.00

Mean

3.00

42.67

157.33

180

1

2

3

2.67

3.33

2.67

34.33

30.67

28.67

164.00

182.67

158.67

Mean

2.89

31.22

168.45

320

1

2

3

1.33

2.67

1.67

37.33

30.00

25.33

168.00

172.33

164.33

Mean

1.89

30.89

168.22

560

1

2

3

2.67

3.00

1.67

30.67

24.67

20.00

129.33

144.00

168.67

Mean

2.45

25.11

147.33

1000

1

2

3

2.33

1.33

1.67

22.33

24.00

19.67

140.00

136.00

136.67

Mean

1.78

22.00

137.56

 

Endpoint:
toxicity to aquatic algae and cyanobacteria
Type of information:
experimental study
Adequacy of study:
supporting study
Study period:
start date 26-02-2008
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Guideline study with acceptable restrictions (no test substance purity mentioned, no detailed description of exprimental conditions, positive control not reported, raw data lacking).
Qualifier:
according to
Guideline:
OECD Guideline 201 (Alga, Growth Inhibition Test)
Qualifier:
according to
Guideline:
other: OECD Guideline 23 (Aquatic Toxicity Testing of Difficult Substances and Mixtures)
GLP compliance:
no
Analytical monitoring:
no
Vehicle:
no
Details on test solutions:
PREPARATION AND APPLICATION OF TEST SOLUTION - Method: Water Accommodated Fraction (WAF) method: A aqueous solution was saturated with test substance and was stirred moderately for 68 hours by magnetic stirring with a 4 hours of settling period afterwards. The aqueous phase containing WAF was used to perform the test.
Test organisms (species):
Pseudokirchneriella subcapitata (previous names: Raphidocelis subcapitata, Selenastrum capricornutum)
Details on test organisms:
TEST ORGANISM- Common name: Green algae- Source (laboratory, culture collection): Microbiotests Inc., Nazareth, Belgium- The algae were prepared and conditioned by the supplier in alginate beads and were stored at 4 ± 3 °C until use- Lot number: SC131107
Test type:
static
Water media type:
freshwater
Limit test:
yes
Total exposure duration:
72 h
Post exposure observation period:
none
Hardness:
no data
Test temperature:
23 ± 2 °C
pH:
Test begin: 8.1 ± 0.2Test end: 8.9 in control, 9.4 in testing solution
Dissolved oxygen:
no data
Nominal and measured concentrations:
WAF containing 1.011 g/L
Details on test conditions:
TEST SYSTEM- Initial cells density: 10000 cells/mL- Control end cells density: 2794985 cells/mLGROWTH MEDIUM- Standard medium used: yesTEST MEDIUM / WATER PARAMETERS- Source/preparation of dilution water: according to OECD 201OTHER TEST CONDITIONS- Adjustment of pH: no- Photoperiod: continued light- Light intensity and quality: lateral lighting (white continued light, with spectra from 400 nm to 700 nm and intensity about 8000 LuxEFFECT PARAMETERS MEASURED (with observation intervals if applicable): growth inhibition after 24, 48 and 72 h- Determination of cell concentrations: Measurement of the optical density at 670 nm, which was checked by counting with microscope.
Reference substance (positive control):
not specified
Key result
Duration:
72 h
Dose descriptor:
EL50
Effect conc.:
> 1 000 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth rate
Remarks on result:
other: WAF loading rate
Details on results:
- Exponential growth in the control (for algal test): yes- Observation of abnormalities (for algal test): The microscopical examination of the algal cells at test ending confirmed the identity of the organism and revealed that the cells were normal in the test solution (i.e., no cell discoloration was noticed).- The EL50 (72 h) was determined as > 1000 mg/L. The highest observed algae growth inhibition was 15.5%. Overall, the mean algae growth inhibition was 7.9%.- The test item did not produce any particular effect during testing. No technical problem occurred during testing.
Results with reference substance (positive control):
no data
Reported statistics and error estimates:
no data
Validity criteria fulfilled:
yes
Endpoint:
toxicity to aquatic algae and cyanobacteria
Type of information:
experimental study
Adequacy of study:
supporting study
Study period:
29 Feb - 02 Mar 2007
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Guideline study with acceptable restrictions
Qualifier:
according to
Guideline:
OECD Guideline 201 (Alga, Growth Inhibition Test)
Deviations:
no
Qualifier:
according to
Guideline:
EU Method C.3 (Algal Inhibition test)
GLP compliance:
no
Analytical monitoring:
no
Vehicle:
no
Details on test solutions:
PREPARATION AND APPLICATION OF TEST SOLUTION- Method: Water Accomodated Fraction (WAF): A concentration of 100 mg/L of the test substance was moderately stirred in algal medium for 24 h at room temperature. After this incubation time, the undissolved materials were removed by sterile filtration (0.45 µm) to obtain a sterile test substance solution for the algal growth test. The resulting water accommodated fraction was used in the test.
Test organisms (species):
Desmodesmus subspicatus (previous name: Scenedesmus subspicatus)
Details on test organisms:
TEST ORGANISM- Strain: 86.81 SAG- Source: obtained from the collection of Algal Cultures, Institute of Freshwater Ecology, University of Göttingen, Göttingen, Germany Age of inoculum (at test initiation): Exponentially growing liquid preculture were used to inoculate sterile test flasks.- Method of cultivation: 250 mL flask containing 100 mL of sterile OECD medium inoculated with cell material from axenic slope culture, continuous illumination from warm white fluorescent tubes (8500 - 9000 lux), temperature: 22 ± 0.2 °C thermocontrolled room, periodically conducted reference test with potassium dichromate.
Test type:
static
Water media type:
freshwater
Limit test:
yes
Total exposure duration:
72 h
Hardness:
not stated
Test temperature:
22 ± 0.2 °C
pH:
8.0 ± 0.2
Nominal and measured concentrations:
Nominal: 100 mg/L
Details on test conditions:
TEST SYSTEM- Test vessel: Erlenmeyer flask- Material: glass; Size: 250 mL; Fill volume: 100 mL - Initial cells density: 10000 - 20000/mL- No. of vessels per concentration: 3- No. of vessels per control: 5TEST MEDIUM / WATER PARAMETERS- Source/preparation of dilution water: OECD medium- Culture medium different from test medium: no- Intervals of water quality measurement: Temperature was determined in a control flask at the start and at the end of the test. The pH was determined in 1 control flask after sterilization before the test and in all test vessels at the end of the test. Observations of mis-shapen cells and cell-debris were made after 24, 48 and 72 h test duration.OTHER TEST CONDITIONS- Photoperiod: continuous- Light intensity and quality: warm white fluorescent tubes (8500-9000 lux)EFFECT PARAMETERS MEASURED: Algal growth was recorded after 24, 48 and 72 h test duration.- Determination of cell concentrations: using a spectrophotometer (680 nm wavelength). Aliquots of 5 mL were removed from each test substance served as controls. The starting cell density was determined using a counting chamber.
Reference substance (positive control):
no
Key result
Duration:
72 h
Dose descriptor:
EL50
Effect conc.:
> 100 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth rate
Remarks on result:
other: EL50 (24-72h)
Key result
Duration:
72 h
Dose descriptor:
EL0
Effect conc.:
>= 100 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
growth rate
Remarks on result:
other: EL0 (24-72h)
Key result
Duration:
72 h
Dose descriptor:
EL50
Effect conc.:
> 100 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
biomass
Remarks on result:
other: EL50 (24-72h)
Key result
Duration:
72 h
Dose descriptor:
EL0
Effect conc.:
>= 100 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
biomass
Remarks on result:
other: EL0 (24-72h)
Details on results:
- Exponential growth in the control: yes- Observation of abnormalities: no

At the WAF loading rate of 100 mg/L no inhibition with respect to algal growth rate and algal cell growth (area under growth curve) compared to the untreated controls were observed. The no-observed-effect concentration for growth rates (ErL0) and biomass production (EbL0) with respect to the loading rate was ≥ 100 mg/L. The EL50 -value was conducted as EL50 (24 -72 h). But the EL50 can also be stated as EL50 (72 h) > 100 mg/L for the algal growth rate and algal cell growth.

Table 1: Cell concentration (A680) in individual test cultures after 24, 48 and 72 h of exposure to the test material. ((b) = Mean absorbance (A680))

Nominal concentration [mg/L]

Code

Cell concentration (A680)

0 h (b)

24 h

48 h

72 h

Control

A

B

C

D

E

0.008

0.008

0.008

0.008

0.008

0.033

0.038

0.038

0.036

0.040

0.228

0.222

0.208

0.212

0.233

0.685

0.733

0.676

0.624

0.694

100

A

B

C

0.008

0.008

0.008

0.040

0.038

0.044

0.224

0.207

0.207

0.700

0.631

0.675

 

Endpoint:
toxicity to aquatic algae and cyanobacteria
Type of information:
experimental study
Adequacy of study:
supporting study
Study period:
21 Jul - 24 Aug 1995
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: see 'Remark'
Remarks:
GLP Guideline study with acceptable restrictions: The light intensity exceeded the guideline requirements of 3870 to 4730 lux. The intensity ranged from 4559 to 5118 lux during the study. This minor deviation is not believed to have had any adverse effects on the study.
Qualifier:
according to
Guideline:
OECD Guideline 201 (Alga, Growth Inhibition Test)
Deviations:
yes
Remarks:
The light intensity exceeded the guideline requirements of 3870 to 4730 lux. The intensity ranged from 4559 to 5118 lux during the study.
GLP compliance:
yes
Analytical monitoring:
yes
Details on sampling:
- Concentrations: control; 1000 mg/L treatment
- Sampling method: Samples were removed from the treatment and the control on day 0 and at termination of the study.
Vehicle:
no
Details on test solutions:
PREPARATION AND APPLICATION OF TEST SOLUTION
- Method: Individual treatment solutions (WAF) were prepared by adding the appropriate amount of the test substance to 1 L of algal nutrient media. The vessels were closed with cotton gauze stoppers to minimize evaporation and/or volatilization.The solutions were mixed at ≤ 10% vortex on magnetic stirplates with Teflon coated stirbars for approx. 24 hours. The 1000 mg/L treatment solution appeared slightly cloudy with undissolved test material floating on the surface. All remaining treatment solutions appeared clear with undissolved test material floating on the surface. After mixing, the solutions were allowed to settle for approx. one hour before the WAFs were removed through the outlet at the bottom of the aspirator bottle.
- Evidence of undissolved material: Once prepared, no test substance insolubility was observed in the WAF solutions during the study.
Test organisms (species):
Scenedesmus capricornutum
Details on test organisms:
TEST ORGANISM
- Strain: 1648
- Source: cultured in the Environmental Toxicology and Chemistry Laboratory of Exxon Biomedical Sciences Inc. Initial strain provided by the Department of Botany, University of Texas
- Age of inoculum: Algae were taken from stock cultures in their log phase of growth (culture date: 19 Jul 1995).
- Method of cultivation: Algae are cultured in algal nutrient media prepared with distilled water and reagent grade chemicals. Culturesd were held at 24 ± 2 °C under continuous illumination.

ACCLIMATION
- Culturing media and conditions: same as test
Test type:
static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
96 h
Remarks on exposure duration:
± 1 h
Hardness:
not stated
Test temperature:
22.8 ± 0.8 °C
pH:
7.4 (test inition)
8.7 - 9.0 (test end)
Nominal and measured concentrations:
Nominal: 1000 mg/L, 500 mg/L, 250 mg/L, 125 mg/L and 62.5 mg/L ( loading rate WAFs)
Details on test conditions:
TEST SYSTEM
- Test vessel: Erlenmeyer flask
- Type: closed with cotton gauze stoppers
- Material: glass; Size: 125 mL; Fill volume: 80 mL
- Initial cells density: 10000 cells/mL
- Control end cells density: 4300000 cells/mL
- No. of vessels per concentration: 4
- No. of vessels per control: 4
-other: Each test flask was placed on a shaker table (100 rpm) for the duration of the study to keep the algae in suspension and facilitate the transfer of carbon dioxide.

GROWTH MEDIUM
- Standard medium used: yes, according to guideline: EPA-600/9-78-018

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: reverse osmosis dialyzed well water
- Culture medium different from test medium: no
- Intervals of water quality measurement: Temperature was continuously monitored. The pH was measured on day 0 and at termination.

OTHER TEST CONDITIONS
- Sterile test conditions: yes
- Photoperiod: continuous illumination
- Light intensity and quality: 4599 - 5118 lux (provided by cool-white fluorescent bulbs; oscillation rate: 100 oscillations/min.)

EFFECT PARAMETERS MEASURED: Cell densities were monitored after 24, 48, 72 and 96 h test duration.
- Determination of cell concentrations: Turner filter fluorimeter
Reference substance (positive control):
no
Key result
Duration:
72 h
Dose descriptor:
NOELR
Effect conc.:
>= 1 000 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Remarks:
(WAF)
Basis for effect:
growth rate
Key result
Duration:
72 h
Dose descriptor:
EL50
Effect conc.:
> 1 000 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Remarks:
(WAF)
Basis for effect:
growth rate
Details on results:
- Exponential growth in the control: yes
- Observation of abnormalities: no
- Unusual cell shape: no
- Colour differences: no
- Flocculation: no
- Adherence to test vessels: no
- Aggregation of algal cells: no

The TOC results indicate that the level of test substance in the WAF was at or near the level of organic carbon in the control. This result confirmes the low water solubility of the test substance (table 1). Therefore, the effect values are determined in relation to the nominal test substance concentration.

Table 1: Results of TOC analysis

Loading level [mg/L]

Total organic carbon [mg/L]*

0 h

4 h

control

5.4 ± 0.5

5.5 ± 0.6

1000 mg/L

6.7 ± 0.7

4.2 ± 1.2

*: triplicate TOC measurements on each sample

Table 2: Mean cell concentrations

Loading level [mg/L]

Mean cell concentration [cells/mL]

0 h

24 h

48 h

72 h

96 h

Control

1.0E4

2.6E4

2.1E5

1.3E6

4.3E6

62.5

1.0E4

2.5E4

1.6E5

9.1E5

3.6E6

125

1.0E4

2.6E4

1.8E5

1.1E6

3.8E6

250

1.0E4

2.5E4

1.7E5

1.0E6

3.7E6

500

1.0E4

2.8E4

2.0E5

1.2E6

3.6E6

1000

1.0E4

2.8E4

2.1E5

1.2E6

3.6E6

Endpoint:
toxicity to aquatic algae and cyanobacteria
Type of information:
experimental study
Adequacy of study:
supporting study
Study period:
30 Jul - 03 Aug 2007
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: see 'Remark'
Remarks:
GLP - Guideline study, tested with the source substance Fatty acids, C16-18 (even numbered), esters with pentaerythritol (CAS 85116-93-4). According to the ECHA guidance document “Practical guide 6: How to report read-across and categories (March 2010)”, the reliability was changed from RL1 to RL2 to reflect the fact that this study was conducted on a read-across substance.
Qualifier:
according to
Guideline:
EPA OPPTS 850.5400 (Algal Toxicity, Tiers I and II)
GLP compliance:
yes (incl. certificate)
Remarks:
Staatliches Gewerbeaufsichtsamt Hildesheim
Analytical monitoring:
yes
Details on sampling:
- Concentrations: The highest loading level and control were analytically verified at the beginning and end of the test via GC-MS.
Vehicle:
no
Details on test solutions:
PREPARATION AND APPLICATION OF TEST SOLUTION
- Method: Water Accomodated Fraction (WAF): Stock solutions of 10, 30 and 100 mg/L were prepared by directly adding appropriate amounts of test substance to dilution water. The stock solutions were shaken with 20 rpm for 24 h at room temperature. After a separation phase of at least 30 min the WAF was taken from the homogenous liquid phase.
Test organisms (species):
Pseudokirchneriella subcapitata (previous names: Raphidocelis subcapitata, Selenastrum capricornutum)
Details on test organisms:
TEST ORGANISM
- Common name: Pseudokirchneriella subcapitata
- Strain: HINDAK
- Source: Sammlung von Algenkulturen (SAG), Pflanzenphysiologisches Institut der Universität Göttingen, Germany
- Age of inoculum: A three day old preculture was used as inoculum.
- Method of cultivation: Fresh stocks were prepared every month on Z-Agar. Light intensity was 35-70 µE/m2*s for 24 h per day. Nutrient
medium Z according to Lüttge et al. (1994) was used as culture medium.

Test type:
static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
96 h
Test temperature:
21.4 - 22.8
pH:
7.44 - 10.11
Nominal and measured concentrations:
Nominal: 10, 30 and 100 mg/L
Measured (100mg/L WAF): 108.3 µg/L at test start; 34.9 µg/L at test end
Measured (control): < limit of quantification
Details on test conditions:
TEST SYSTEM
- Test vessel: Erlenmeyer flasks
- Type: closed with cotton wool plugs
- Size: 250 mL; Fill volume: 100 mL
- Initial cells density: 5134 cells/mL
- Control end cells density: 2655237 cells/mL (mean of 6 values)
- No. of vessels per concentration: 3
- No. of vessels per control: 6

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: Threefold concentrated medium of the OPPTS guideline (3xAAP medium)
- Intervals of water quality measurement: pH at the beginning and end, water temperature hourly, room temperature continously, light intesity prior to the test start

OTHER TEST CONDITIONS
- Sterile test conditions: yes
- Photoperiod: 24 hrs light
- Light intensity and quality: 66.5 µE/m2*s ± 10%

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
- Determination of cell concentrations: Chlorophyll-a-fluorescence excitation at 435 nm, emission at 685 nm. Each replicate was measured 6-fold,
value (flash) no. 3-6 were used for calculation.
The cell density was measured at the beginning of the test (after application) and every 24h.
- Other: At the start and the end of the incubation the cells were checked for unusual cell shape, colour differences in chloroplast morphology,
flocculation, adherence of algae to test containers and aggregation of alga cells.

TEST CONCENTRATIONS
- Range finding study
- Test concentrations: 1, 10 and 100 mg/L
- Results used to determine the conditions for the definitive study: yes, specific growth rate inhibition was 14% at 100 mg/l (nominal) and yield
inhibition 60% at 100 mg/l (nominal)
Reference substance (positive control):
yes
Remarks:
Potassium dichromate
Key result
Duration:
72 h
Dose descriptor:
EL10
Effect conc.:
> 100 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Remarks:
(WAF)
Basis for effect:
growth rate
Key result
Duration:
72 h
Dose descriptor:
EL50
Effect conc.:
> 100 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Remarks:
(WAF)
Basis for effect:
growth rate
Key result
Duration:
96 h
Dose descriptor:
EL10
Effect conc.:
> 100 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Remarks:
(WAF)
Basis for effect:
growth rate
Key result
Duration:
72 h
Dose descriptor:
EL50
Effect conc.:
> 100 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Remarks:
(WAF)
Basis for effect:
biomass
Key result
Duration:
72 h
Dose descriptor:
EL10
Effect conc.:
50.7 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Remarks:
(WAF)
Basis for effect:
biomass
Remarks on result:
other: 39.0 - 70.2 mg/L
Key result
Duration:
96 h
Dose descriptor:
EL10
Effect conc.:
50.7 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Remarks:
(WAF)
Basis for effect:
biomass
Remarks on result:
other: 39.0-70.2 mg/L
Details on results:
- Exponential growth in the control: Yes
Results with reference substance (positive control):
- Results with reference substance valid? Yes
- EC50: 0.86 (72h, growth rate), 0.46 (72h, cell number)
Reported statistics and error estimates:
EC10, EC20 and EC50 value of growth rate and yield inhibition after 96h were calculated by sigmoidal dose-response regression.
Calculation of confidence intervals EC10, EC20 and EC50 values were carried out using standard procedures according to Clopper and Pearson
(1934).

Table 1: Cell densities

Nominal loading level [mg/l]

Replicate No.

Cell densities [cells/ml]

0 hours

24 hours

48 hours

72 hours

96 hours

100

1
2
3

5134
5134
5134

21575
21821
20140

87524
94391
110176

467614
517224
546539

1904254
1918604
1935004

Mean

5134

21179

97364

510459

1919287

30

1
2
3

5134
5134
5134

19095
21534
20468

98409
109684
101074

550434
616854
541414

2804204
2625854
2463904

Mean

5134

20366

103056

569567

2631321

10

1
2
3

5134
5134
5134

21268
21309
23687

136129
125059
90414

677124
821444
592254

2957954
2496704
2761154

Mean

5134

22088

117201

696941

2738604

Control

1
2
3

4

5

6

5134
5134
5134

5134
5134

5134

18664
24322
17455
19997
21370
21678

93079
129159
95744
111939
103124
96769

646989
887454
708694
682044

798894

613369

2244554

2090804

2828804

2664804

3275704

2826754

Mean

5134

20581

104969

722907

2655237

 

Table 2: Evaluation after 96 h

Nominal loading level [mg/L]

Replicate No.

Yield

Inhibition of yield [%]

Growth rate [d-1]

Rate-related inhibition [%]

100

1

2

3

1899120

1913470

1929870

28.34

27.80

27.18

1.479

1.481

1.483

5.15

5.03

4.89

Mean

1914153

27.77

1.481

5.02

30

1

2

3

2799070

2620720

2458770

-5,62

1.11

7.22

1.576

1.559

1.543

-1.06

0.00

1.02

Mean

2626187

0.90

1.559

-0.01

10

1

2

3

2952820

2491570

2756020

-11.42

5.98

-4.00

1.589

1.547

1.572

-1.91

0.81

-0.81

Mean

2733470

-3.15

1.569

-0.64

Control

1

2

3

4

5

6

2239420

2085670

2823670

2659670

3270570

2821620

 

1.520

1.502

1.578

1.563

1.615

1.578

 

Mean

2650103

 

1.559

 

 

Description of key information

Key values determined using OECD guideline 201 and EU test standard C3.

Key value for chemical safety assessment

EC50 for freshwater algae:
0.22 mg/L
EC10 or NOEC for freshwater algae:
0.1 mg/L

Additional information

HATCOL 3331

The batch of HATCOL 3331 tested was a clear colourless liquid with a purity of 97.3% and the substance was not completely soluble in test medium at the concentration tested.

Preparation of test solutions started with a stock solution of 100 mg/l applying 2 days of magnetic stirring to ensure maximum solubility in test medium. The resulting solution was slightly hazy with a floating layer and test substance droplets. Collection of the water phase by siphoning or centrifugation was not an option considering the specific gravity of the test substance. After the stirring period the mixture was therefore filtered through a paper filter(ca. > 5 µm). The filtrate was very slightly hazy.

A limit test was performed exposing exponentially growing algal cultures to a filtered (ca. 5µm) HATCOL 3331 solution prepared at a loading rate of 100 mg/I and a blank-control. The initial cell density was 104cells/ml. The total test period was 72 hours. Samples for determination of actual exposure concentrations were taken at the start, after 24 hours of exposure and at the end of the test period.

 

Analysis of the samples showed that average exposure concentrations were at or above the solubility limit of HATCOL 3331 (I.e. < 0.2 mg/l).

HATCOL 3331 induced no inhibition of cell growth or reduction of growth rate in Selenastrum capricornutum at the concentration obtained in a filtered solution prepared at a loading rate of 100 mg/l, corresponding to an average exposure concentration of 0.22-0.79 mg/I (NOEC).

Due to the very low solubility of HATCOL 3331 in water, concentration levels that might be toxic for algae could not be reached.

 

HATCOL 3344

HATCOL 3344 is a clear colourless liquid with a purity of 96.9%.

All test solutions with a loading rate at or above 1.0 mg/l were prepared separately (loading rates of 1.0, 10 and 100 mg/I). These supersaturated solutions were stirred for two days to reach maximum solubility. Collection of the water phase by siphoning or centrifugation was not an option considering the specific gravity of the test substance. After the stirring period all three mixtures were therefore filtered through a paper filter (Schleicher and Schuell 604, ca. > 5µm). Finally a ten-fold dilution was prepared from the filtrate prepared at a loading rate of 1.0 mg/l. All test solutions were clear and colourless.

A final test was performed exposing exponentially growing algae to 5 µm filtered solutions prepared at loading rates of 1.0, 10 and 100 mg/l and in addition to a ten-fold dilution of the filtrate prepared at a loading rate of 1.0 mg/l for a period of 72 hours. Samples for analytical confirmation of actual exposure concentrations were taken from all test solutions at the start, after 24 hours of exposure and at the end of the test.

 

Analysis of the samples showed that the average exposure concentration in the WAFs prepared at loading rates of 10 and 100 mg/l approximated the solubility limit of HATCOL 3344 (i.e. < 0.2 mg/l). However, since not all components were quantifiable in the calibration chromatograms, it was not possible to determine the concentration of the total test substance. Therefore, the toxicological evaluation was based on loading rates.

Due to the fact that test concentrations below or approximating the water solubility level of HATCOL 3344 could not be analysed as these were below the limit of quantification, a different approach was followed for the calculation of EC and NOEC-values.

 

HATCOL 3344 reduced growth rate of Selenastrum capricornutum significantly at loading rates of 1.0 mg/l and higher.

 

HATOL 5236

HATCOL 5236 is a clear pale yellow liquid with a purity of 97.6%.

All test solutions with a loading rate at or above 1.0 mg/l were prepared separately. These supersaturated solutions were stirred for two days to reach maximum solubility. After the stirring period the mixtures contained a test substance floating layer and test substance particles. Collection of the water phase by siphoning or centrifugation was not an option considering the specific gravity of the test substance. After the stirring period the mixtures were therefore filtered through a paper filter (ca.> 5 µm). In addition a ten-fold dilution was prepared from the filtrate prepared at a loading rate of 1.0mg/l. All test solutions were clear and colourless, except for the two highest test concentrations, which were very slight to slightly hazy, respectively.

A final test was performed exposing exponentially growing algae to 5µm filtered solutions prepared at loading rates of 1.0, 10 and 100mg/l and a ten-fold dilution of the filtrate prepared at a loading rate of 1.0 mg/l for a period of 72 hours. Samples for analytical confirmation of actual exposure concentrations were taken from all test solutions at the start and at the end of the test.

 

Analysis of the samples showed that the average exposure concentration in the WAF prepared at a loading rate of 100mg/l was at above or approximated the solubility limit of HATCOL 5236 (i.e.<0.2 mg/l). Since toxicological relevant test concentrations could not be analysed, biological results were based on loading rates.

 

Due to the fact that test concentrations below or approximating the water solubility level of HATCOL 5236 could not be analysed as these were below the limit of quantification, a different approach was followed for the calculation of EC and NOEC-values.

 

HATCOL 5236 reduced growth rate of Selenastrum capricamutum significantly at loading rates of 10 mg/l and higher.

The EL50 for total cell growth inhibition (EBL50:0·72h) was 8.0 mg/l with a 95% confidence interval ranging from 3.5 to 19 mg/l.

The EL10 for total cell growth inhibition (EBL10:0·72h) was 0.71 mg/l with a 95% confidence interval ranging from 0.28 to 1.80 mg/l.

As growth rate is derived from the slope under the growth curve in a logarithmic plot, the measure of the specific growth rate is preferable over biomass following from the mathematical nature of exponential growth. In addition total cell growth is depended on growth rate, whereas growth rate is independent from cell density during exponential cell growth as was the case in the present test for all concentrations. For evaluation of the results and for classification of the test substance it is therefore advised to use growth rate rather than total cell growth.

The EL50 for growth rate reduction (ERL50:0-72h) was 47 mg/l with a 95% confidence interval ranging from 9.9 to 230 mg/l.

The EL10 for growth rate reduction (ERL10:0-72h) was 2.0 mg/l with a 95% confidence interval ranging from 0.41 to 9.6 mg/l.

The NOELR for both cell growth inhibition and growth rate reduction was 1.0 mg/l.

CAS 11138 -60 -6

The first study with CAS 11138-60-6 conducted in accordance with OECD Guideline 201 determined a no-observed-effect concentration for growth rate (ErL0) of ≥ 100 mg/L and an ErL50 > 100 mg/L (WAF loading rate).

In the second study with CAS 11138-60-6 conducted in accordance with OECD Guideline 201, the 72h EL50 (WAF loading rate, based on growth rate) was determined to be > 1000 mg/L.

CAS 91050 -88 -3

In the study with CAS 91050-88-3 conducted in accordance with OECD Guideline 201, the 72h EL50 (WAF loading rate, based on growth rate) was determined to be > 1000 mg/L.

CAS 189200-42-8

The study with fatty acids, C8-10 mixed esters with dipentaerythritol, isooctanoic acid, pentaerythritol and tripentaerythritol was performed according to OECD 201 under GLP conditions (Febbo, 1995). The green algae Scenedesmus capricornutum was exposed to nominal concentrations of 62.5 mg/L, 125 mg/L, 250 mg/L, 500 mg/L and 1000 mg/L. The test solution was prepared by adding the appropriate amount of test substance with subsequent stirring and sampling of the aqueous portions (WAFs) through the outlet at the bottom of the vessels. No inhibition of growth of Scenedesmus capricornutum up to the limit of water solubility was observed resulting in an EL50 > 1000 mg/L (nominal). A NOELR of ≥ 1000 mg/L was determined based on effects on growth rate.