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Toxicity to aquatic algae and cyanobacteria

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toxicity to aquatic algae and cyanobacteria
Type of information:
experimental study
Adequacy of study:
supporting study
Study period:
1982-09-17 To 1982-10-01
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Comparable to guideline study with acceptable restrictions
Reason / purpose:
reference to same study
according to
other: Payne AG, Hall RH, 1979, in Aquatic Toxicology, ASTM, STP 667, pp. 171-180; and US EPA, 1978, The Selenastrum capricornutum Printz algal assay. Deviations, reliability, and validity will be evaluated using the USEPA OPPTS 850.5400 (1996) guideline.
Principles of method if other than guideline:
Not applicable
GLP compliance:
not specified
Analytical monitoring:
Details on sampling:
- Concentrations: Not available
- Sampling method: Not available
- Sample storage conditions before analysis: Not available
Details on test solutions:
- Method: A primary stock solution of X0235.01 was prepared by adding a weighed amount of test material to algal growth medium and other stock solutions were prepared by serial dilution. A growth medium control was conducted concurrently and contained no test material. All test concentrations, except 1,000 ppm, were prepared by pipeting 1 milliliter (m2) of the appropriate stock solution to each test flask. The 1,000 ppm test concentration was prepared by adding 50ml of primary stock solution to each test flask.
- Eluate: Not applicable
- Differential loading: Not applicable
- Controls: AAP medium
- Chemical name of vehicle (organic solvent, emulsifier or dispersant): Not applicable
- Concentration of vehicle in test medium (stock solution and final test solution(s) including control(s)): Not available
- Evidence of undissolved material (e.g. precipitate, surface film, etc): None
Test organisms (species):
Microcystis aeruginosa
Details on test organisms:
- Common name: Green algae
- Strain: Not available
- Source (laboratory, culture collection): University of Texas at Austin, Austin, Texas
- Age of inoculum (at test initiation): Not available
- Method of cultivation:

- Acclimation period: Not available
- Culturing media and conditions (same as test or not): Same as test
- Any deformed or abnormal cells observed: Not available
Test type:
Water media type:
Limit test:
Total exposure duration:
120 h
Remarks on exposure duration:
96 hour results reported here
Post exposure observation period:
Yes (9 days)
Not available
Test temperature:
Static bioassays were conducted at 24 ± 1 °C in water bath
Not available
Dissolved oxygen:
Not available
Not applicable
Nominal and measured concentrations:
Nominal laboratory exposure concentrations based on active ingredient were control, 0.01, 0.05, 0.1, 0.5, 1.0 and 1,000mg/L
No measurements of test concentrations.
Details on test conditions:
- Test vessel:
- Type (delete if not applicable): open / closed: Not available
- Material, size, headspace, fill volume: Test containers were 125-ml flasks with 50 ml of test medium
- Aeration: Not available
- Type of flow-through (e.g. peristaltic or proportional diluter): Not applicable
- Renewal rate of test solution (frequency/flow rate): Not available
- Initial cells density: 1x10(5) cells/ml
- Control end cells density: 18.5x10(5) cells/ml
- No. of vessels per concentration (replicates): 3
- No. of vessels per control (replicates): 3

- Standard medium used: Yes, AAP nutrient medium

- Source/preparation of dilution water: Regular Algal Assay Procedure (AAP) medium prepared with deionized water
- Total organic carbon: Not available
- Particulate matter: Not available
- Metals: Not available
- Pesticides: Not available
- Chlorine: Not available
- Alkalinity: Not available
- Ca/mg ratio: Not available
- Conductivity: Not available
- Culture medium different from test medium: No
- Intervals of water quality measurement: Not available

- Sterile test conditions: Yes
- Adjustment of pH: Not applicable
- Photoperiod: Not available
- Light intensity and quality: Approximately 2,000 lux

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
- Determination of cell concentrations: Hemacytometer
- Cell counts were made on day 0,2,3,4,5.

- Spacing factor for test concentrations: 2-5 (except for the highest test concentration of 1000 mg/L)
- Justification for using less concentrations than requested by guideline: Not applicable
- Range finding study: no
Reference substance (positive control):
96 h
Dose descriptor:
Effect conc.:
0.91 mg/L
Nominal / measured:
Conc. based on:
act. ingr.
Basis for effect:
cell number
Remarks on result:
other: 95%CL: 0.84- 10mg/L
Details on results:
- Exponential growth in the control (for algal test): Yes (18.5x growth)
- Observation of abnormalities (for algal test): Not available
- Any stimulation of growth found in any treatment: Not available
- Any observations (e.g. precipitation) that might cause a difference between measured and nominal values: None
- Effect concentrations exceeding solubility of substance in test medium: None
Results with reference substance (positive control):
Not applicable
Reported statistics and error estimates:
The EC50 values were calculated using the following three statistical methods: moving average angle analysis, Probit analysis, and binominal probability. The results of the moving average angle method were used to report the EC50 values.

Comparison was also made to in situ studies conducted in which lake water was bottled and suspended in Lake Acton (Ohio) for 3 hour periods. The mean 3-h EC50(photosynthesis) for the in situ studies was 3.4 mg/L (0.5-8.0 mg/L).Using the acute to chronic ratio calculation (documented in Annex 3 of the LAS SIAR), the EC50/3 for Microcystis is 0.3 mg/L.   The NOEC normalized by van de Plassche et al. (1999) to C11.6LAS was 0.35 mg/L. 

Validity criteria fulfilled:
In a 96 hour algae growth inhibition test, the EC50 of LAS to Microcystis aeruginosa was 0.91 mg/L.
Executive summary:

In a 96 hour algae growth inhibition test, the green algae Microcystis aeruginosa was exposed to Linear Alkylbenzene Sulfonate (C11.9 LAS) in accordance with USEPA OPPTS 850.5400. The nominal test concentrations were 0 (control), 0.01, 0.05, 0.1, 0.5, 1.0 and 1,000 mg a.i./L.

The 96 hour EC50, based on cell number, was 0.91 mg a.i./L (0.84 -10.0). The NOEC is estimated to be 0.35 mg/L for C11.6 LAS (van de Plassche et al., 1999).

This algal growth inhibition test satisfies the guideline requirements of the USEPA OPPTS 850.5400.

Description of key information

Four key studies are used to characterize the toxicity of LAS to aquatic algae. In the first study (Lewis 1986; Lewis and Hamm 1986; Larson and Schaeffer 1982; van de Plassche et al 1999), the toxicity of the test substance to aquatic algae was evaluated. Pseudokircheneriella subcaptitata, formerly Selenastrum capricornutum, was exposed to the test substance for 96 hrs and the cell density measured. The 96 hr NOEC was 0.5 mg/l, the LOEC was 1 mg/L, and the EC50 was 29.0 mg/L based on cell density. When normalized to C11.6LAS, the NOEC value becomes 0.58 mg/L. Similarly, in a second algae growth inhibition test (Ward 1982; van de Plassche et al 1999), the green algae Microcystis aeruginosa was exposed to C11.9LAS for 96 hours. Nominal test concentrations were 0 (control), 0.01, 0.05, 0.1, 0.5, 1.0 and 1,000 mg a.i./L. The resultant 96 hour EC50, based on cell number, was 0.91 mg a.i./L. The NOEC normalized for C11.6LAS is estimated to be 0.35 mg/L.

In a third study (Scholz 1992), Scenedesmus subspicatus was exposed to concentrations of 0, 0.6, 2.4, 10, 40, or 160 mg/L of C11.6LAS for 72 hours. The 72-hr NOEC was 2.4 mg/L, the EbC50 was 47.3 mg/L, and the ErC50 was 127.9 mg/L for algae. Normalization is not required since the compound tested was already C11.6LAS. Similarly, in a fourth study (Muehlberg 1984), the algae Chlorella kessleri was exposed to concentrations of 0, 0.01, 0.03, 0.1, 0.3, 1, 3, 10, 30, 100, 300, and 1000 mg/L (nominal) of C11.6LAS for 15 days. The resultant NOEC was 3.1 mg/L active ingredient, and the LOEC was 10 mg/L active ingredient. Again, no normalization is required because the study was conducted on C11.6LAS.

Key value for chemical safety assessment

EC50 for freshwater algae:
7.39 mg/L
EC10 or NOEC for freshwater algae:
0.268 mg/L

Additional information