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Toxicity to aquatic plants other than algae

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toxicity to aquatic plants other than algae
Type of information:
experimental study
Adequacy of study:
weight of evidence
Study period:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
comparable to guideline study with acceptable restrictions
Cross-referenceopen allclose all
Reason / purpose for cross-reference:
reference to same study
Reason / purpose for cross-reference:
reference to other study

Data source

Reference Type:
study report

Materials and methods

Test guideline
no guideline followed
Principles of method if other than guideline:
Vegetative shoots of Elodea canadensis were allowed to grow at four different test concentrations in a replicated aquatic community (model ecosystem) for 28 d. Growth and productivity of Elodea were recorded and NOEC was calculated.
GLP compliance:
Pre-GLP study

Test material

Constituent 1
Chemical structure
Reference substance name:
Benzenesulfonic acid, C10-13-alkyl derivs., sodium salts
EC Number:
EC Name:
Benzenesulfonic acid, C10-13-alkyl derivs., sodium salts
Cas Number:
Molecular formula:
Not applicable for UVCB
sodium 4-undecylbenzenesulfonate
Constituent 2
Reference substance name:
Linear alkylbenzene sulfonate
Linear alkylbenzene sulfonate
Details on test material:
- Name of test material: Two LAS test materials were used in this study:
1. 14C-radiolabeled C12LAS (pure C12 chainlength) (GTS72922), and
2. Unlabelled C11.6 LAS (comprised of C10,C11,C12,C13 chainlengths) (GTS72923)
- Substance type: Pure active substance
- Physical state: Not reported
- Specific activity: 831 µCi/mmole
- Locations of the label: uniformly labeled with 14 C in the benzene ring
- Stability under test conditions: Not reported
- Storage condition of test material: Not reported

Sampling and analysis

Analytical monitoring:
Details on sampling:
Please see the section below. The study report does not include details about sampling.

Test solutions

Details on test solutions:
PREPARATION AND APPLICATION OF TEST SOLUTION: Preparation of test solutions is not reported. The test concentrations were delivered to the duplicate test vessels by a modified Mount and Brungs 1 L proportional diluter.

Test organisms

Test organisms (species):
other: Elodea canadensis
Details on test organisms:
- Common name: Elodea
- Strain: Not reported
- Source (laboratory, culture collection): Not reported
- Age of inoculum (at test initiation): vegetative shoots (10 cm long)
- Method of cultivation: Not reported

- Acclimation period: 3 d
- Culturing media and conditions (same as test or not): Not reported
- Any deformed or abnormal cells observed: Not reported

Study design

Test type:
Water media type:
Limit test:
Total exposure duration:
28 d
Post exposure observation period:

Test conditions

120 mg/L CaCO3
Test temperature:
21 ± 2°C
Mean pH: 8.1 ± 0.2
Dissolved oxygen:
Mean Dissolved Oxygen Concentration (DOC): 7.8 mg/L (ranged, 7.0-9.0)
Nominal and measured concentrations:
Nominal test concentrations were: 0, 0.5, 1.0, 2.0, and 4.0 mg/L. MBAS and radiometric counts confirmed the expected nominal concentrations. Two figures in the study report show the confirmation of nominal test concentrations, but details not provided.
Details on test conditions:
- Incubation chamber used: Not reported
- Test vessel: Aquaria containing 2.5 cm of natural lake sediment
- Type: Open
- Material: 19 L glass
- Type of cover: Not reported
- Aeration: No (test was flow-through)
- Agitation: No
- Type of flow-through: Proportional diluter
- Renewal rate of test solution: 8 replacement volumes/d
- Control end cells density: Not reported
- No. of shoots per vessel: 8 vegetative shoots
- No. of frond per colony: Not reported
- No. of vessels per concentration (replicates): Two
- No. of vessels per negative control (replicates): Two :
- No. of vessels per vehicle control (replicates): Not applicable

- Standard medium used: No
- Detailed composition if non-standard medium was used: Not reported

SEDIMENT USED (for rooted aquatic vascular plants)
- Origin: Winton Lake, Cincinnati, Ohio
- Textural classification (% sand, %silt and clay): Not reported
- organic carbon (%): Not reported
- Geographic location: Cincinnati, Ohio

- Source/preparation of dilution water: The dilution water was carbon and reverse-osmosis filtered well water
- Total organic carbon: Not reported
- Particulate matter: Not reported
- Metals (mg/L): Zinc: <0.001; Lead: <0.01; Iron: <0.05; Copper: <0.001,
- Nitrate (mg/L): <0.05
- Pesticides: Not reported
- Chlorine: Not reported
- Alkalinity: Not reported
- Ca/mg ratio: Not reported
- Conductivity: Not reported
- Culture medium different from test medium: No
- Intervals of water quality measurement: Twice weekly
- Other: Temperature was monitored continuously with a recording thermograph

- Sterile test conditions: Not reported
- Adjustment of pH: Not reported
- Photoperiod: Not reported
- Light intensity and quality: Not reported

EFFECT PARAMETERS MEASURED: Includes growth (as total length) and productivity (as ash-free dry weight) of the Elodea at the end of 28 d exposure period. Amount of 14C-LAS taken up by the plant was measured by combustion analysis.
- Determination of frond number: Not reported
- Determination of biomass: Yes, dry weight
- Determination of frond area: Not reported

NEGATIVE CONTROL PERFORMED: Yes (received only filtered well water)

- Sampling frequency: Only on Day 28, as sampling of test species was not done during exposure period.
- Sampling method: For the amount of 14C-LAS taken up by the plant, triplicate samples of the test species were taken at 28 d sampling period, rinsed, dried at 30°C for 24 h, and weighed in tared plancets prior to combustion analyses for radiometric counting of 14C-LAS content
- Sample storage conditions before analysis: For 14C-LAS analysis, samples were dried at 30°C for 24 h before analysis

Reference substance (positive control):

Results and discussion

Effect concentrations
Key result
28 d
Dose descriptor:
Effect conc.:
>= 4 mg/L
Nominal / measured:
Conc. based on:
act. ingr.
Remarks on result:
other: Nominal concentration confirmed by analytical measurement.
Details on results:
- Any visual signs of phytotoxicity (abnormalities): Not reported
- Decrease in frond size: Not reported
- Necrosis / chlorosis: Not reported
- Sinking of fronds: Not reported
- Other: The growth and productivity was not inhibited at any test concentration, including the highest (4.0 mg/L).
- Any stimulation of growth found in any treatment: Growth throughout the exposure period approximately doubled the initial biomass of the vegetative shoots used at the start of the exposure (Initial biomass = 37 mg ashed-free dry weight; overall mean for all treatment concentrations = approx. 72 mg ashed-free dry weight). Overlap of 95% confidence limits for all treatments with unexposed control production confirms the lack of LAS effects throughout the exposure period.
- Any observations (e.g. precipitation) that might cause a difference between measured and nominal values: Not reported
- Effect concentrations exceeding solubility of substance in test medium: No
- Bioconcentration factor: Mean bioconcentration factor 629.5 based on a wet weight basis
Results with reference substance (positive control):
Positive control was not included in the study.
Reported statistics and error estimates:
Not reported

Applicant's summary and conclusion

Validity criteria fulfilled:
not applicable
The 28 d NOEC of C12 LAS to Elodea canadensis in a model ecosystem study was > 4 mg/L.
Executive summary:

The long term toxicity of C12 LAS (linear alkylbenzene sulfonate) to the aquatic plant (Elodea canadensis) was evaluated in a 28 day model ecosystem flow-through test. The nominal test concentrations were 0, 0.5, 1.0, 2.0, and 4.0 mg/L, confirmed by analytical measurements.

The growth and productivity of the Elodea was recorded after the exposure period of 28 d.

Growth inhibition was not observed even at highest tested concentration (4 mg/L). Growth throughout the exposure period approximately doubled the initial biomass of the vegetative shoots used at the start of the exposure.  The initial biomass was 37 mg ashed-free dry weight; the overall mean for all treatment concentrations was 72 mg ashed-free dry weight. Overlap of 95% confidence limits for all treatments with unexposed control production confirmed the lack of LAS effects throughout the exposure period.

Hence, the NOEC was found to be >4 mg/L.