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Diss Factsheets

Ecotoxicological information

Toxicity to aquatic plants other than algae

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Administrative data

Link to relevant study record(s)

toxicity to aquatic plants other than algae
Type of information:
experimental study
Adequacy of study:
supporting study
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: guideline study; restricted by non-GLP and minor deficiencies in reporting
according to guideline
OECD Guideline 221 (Lemna sp. Growth Inhibition Test)
GLP compliance:
not specified
Analytical monitoring:
Test organisms (species):
Lemna minor
Details on test organisms:
- Common name: duckweed
- Strain:
- Source (laboratory, culture collection): ECT Oekotoxikologie (Floersheim, Germany)
- Age of inoculum (at test initiation):
- Method of cultivation: 20 ± 1 °C, photoperiod: 24 h with 6000-6500 lx

- Acclimation period: several week
- Culturing media and conditions (same as test or not): same as test
- Any deformed or abnormal cells observed: no
Test type:
Water media type:
Limit test:
Total exposure duration:
7 d
Test temperature:
20 ± 1 °C
Nominal and measured concentrations:
nominal: control, 1.0, 2.5, 5.0, 10.0, and 20.0 mg/L
Details on test conditions:
- Incubation chamber used: yes/no
- Test vessel: 250 mL beaker (Ø 10.5 cm)
- Type (delete if not applicable): open / closed
- Material, size, headspace, fill volume: glass, 200 mL test medium
- Type of cover:
- Aeration:
- Agitation: yes/no
- Type of flow-through (e.g. peristaltic or proportional diluter):
- Renewal rate of test solution (frequency/flow rate):
- Control end cells density:
- No. of colonies per vessel:
- No. of fronds per colony: 12
- No. of vessels per concentration (replicates): 3
- No. of vessels per control (replicates): 6
- No. of vessels per vehicle control (replicates): -

- Standard medium used: yes/no
- Detailed composition if non-standard medium was used:

SEDIMENT USED (for rooted aquatic vascular plants)
- Origin:
- Textural classification (% sand, %silt and clay):
- organic carbon (%):
- Geographic location:

- Source/preparation of dilution water:
- Total organic carbon:
- Particulate matter:
- Metals:
- Pesticides:
- Chlorine:
- Alkalinity:
- Ca/mg ratio:
- Conductivity:
- Culture medium different from test medium:
- Intervals of water quality measurement:

- Sterile test conditions: yes/no
- Adjustment of pH:
- Photoperiod: 24 h light
- Light intensity and quality: 6000-6500 lux

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
- Determination of frond number: [manual counting / computerized image analysis]
- Determination of biomass: [dry weight / fresh
- Determination of frond area:
- Other:

- Test concentrations: no data
- Results used to determine the conditions for the definitive study: no data
Reference substance (positive control):
not specified
Key result
7 d
Dose descriptor:
Effect conc.:
3.94 mg/L
95% CI:
>= 1.95 - <= 7.98
Nominal / measured:
Conc. based on:
test mat.
Basis for effect:
growth rate
Results with reference substance (positive control):
no data
Reported statistics and error estimates:
D'Agostino, Pearson, Kolmogorov-Smirnov, and Barlett's test for check of normality and homogeneity of variance of dataset
significance by one-way ANOVA followed by Dunnett's multiple comparison test -> normal distribution; or otherwise Kruskal-Wallis followed by Dunn's posttest
For two samples test: normal distribution: Fisher's exact test for quantal data or unpaired t-test, otherwise: Mann-Whitney test
For determination of effect concentrations: log-transformation and non-linear regression (significance level p< 0.05)
Validity criteria fulfilled:
Based on experimental observations an EC10 (7d)=3.94 mg/L for 1H-Benzotriazole was calculated. As toxicity to aquatic plants is not a standard requirement according to the REACH Annexes the information was considered as reliable and used as supporting information for the assessment of the aquatic toxicity of Benzotriazole.
Executive summary:

Effects of 1H-Benzotriazole on growth of Lemna minor were examined according OECD guideline 221. Fronds of Lemna were exposed to five different concentrations and number and abnormalities, like discolorations or necrotic tissues etc., were recorded daily. In addition to the inhibition of the growth rate decreasing size of the fronds with gradient concentration was observed.

Description of key information

EC10 value based on experimental observations in an OECD 221 study with Lemna minor.

Key value for chemical safety assessment

EC10 or NOEC for freshwater plants:
3.94 mg/L

Additional information