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EC number: 701-122-3 | CAS number: 106185-75-5
Table 1: Mean cell numbers (as determined by Hemacytometer) during a 96-hour continuous exposure of the freshwater green alga, Selenastrum capricornatum, to the test item under static test conditions
Measured concentrations (mg/L)
Mean cell number (x104) /mLa
a: Values are mean of triplicate test chambers.
b: Percent inhibition is determined against the vehicle control at 96 -hours as: %inhibition = ((cells/mL of vehicle control - cells/mL of treatment)/ (cells/mL of vehicle control)) x 100
c: Replicate C was an outlier and was not included in the mean calculation
d: Significant reduction in growth compared to the vehicle control (α = 0.05)
Table 2: Calculated EC50values based on mean measured concentrations for the freshwater green alga,Selenastrum capricornatum, exposed to the test item under static conditions
EC50value (mg a.i/L)
95% confidence limit (mg a.i/L)
a: greater than the highest concentration tested
b: Root Mean Square Error. Smaller values indicate a better fit of the regression line. The minimum possible value is 0.0
Table 3: Daily cell counts of the freshwater green alga, Selenastrum capricornutum, during a 96-hour static exposure to the test item
Mean measured concentrations (mg/L)
Cells per mL (x104)
In a 96 hour acute toxicity study, the cultures of Selenastrum capricornatum were exposed to the test item at measured concentrations of 0 (control and vehicle control), 0.44, 0.80, 1.2, 2.6, 3.6 mg a.i./L under static conditions in accordance with the EPA OPPTS 850.5400 guideline. The EC50 and NOEC values based on cell density were 2.5 and 0.44 mg a.i./L, respectively. The % growth inhibition in the treated algal culture as compared to the vehicle control ranged from 12 to 56.
There were no compound-related phytotoxic effects.
This toxicity study is considered as acceptable and satisfies with the guidelines requirements for freshwater green alga toxicity study.
Test Organism: Freshwater green alga, Selenastrum capricornatum
Test Type (Flowthrough, Static, Static Renewal): static
96-hr EC50: 2.5 mg a.i./L 95% C.I.: 2.1 to 2.8 mg a.i./L
96-hr NOEC: 0.44mg a.i./L
Endpoint(s) Effected: inhibition growth
The substance exhibits an 96h-EC50 for freshwater algae of 2.5 mg/L and a 96h-NOEC of 0.44 mg/L.
One experimental study and one QSAR are available to determine the toxicity to aquatic algae.
In a 96-hour acute toxicity study, cultures of Selenastrum capricornatum were exposed to Super Radjanol at nominal concentrations of 0, 0.65, 1.3, 2.5, 5.0, 10.0 mg/L under static conditions in accordance with the EPA OPPTS 850.5400 guideline. The concentrations of the test item (with and without algae) were determined by HPLC at the start and at the end of the test. The NOEC and EC50 values based on growth rate were 0.44 and 2.5 mg/L, respectively.
This toxicity study is classified as acceptable and satisfies the guideline requirement for growth inhibition of algae study.
A QSAR model was used to predict the inhibition of growth to algae of the test item 2-ethyl-4-(2,2,3-trimethyl-3-cyclopenten-1-yl)-(2E)-buten-1-ol. This QSAR has been validated to be compliant with the OECD recommendations for QSAR modeling (OECD, 2004) and predicts the endpoint value which would be expected when testing the substance under experimental conditions in a laboratory following Guideline for Testing of Chemicals No. 201, "Freshwater Alga and Cyanobacteria, Growth Inhibition Test" (1), referenced as Method C.3 of Commission Regulation No. 440/2008 (2). The first criterion predicted was the NOECr (No Observed Effect Concentration for specific growth rate), a tested concentration which is expected to cause no effect on intrinsic rate of growth of the test system within a period of 72 hours. The other predicted criterion was the ErC50(Median Effective Concentration for specific growth rate), a statistically derived concentration which is expected to cause 50% inhibition of intrinsic rate of growth of the test system within a period of 72 hours.
The QSAR models are based on validated data for a training set of 40 chemicals derived from 72-hour ErC50and 31 chemicals derived from 72-hour NOECr test on algae, for which the concentrations of the test item had been determined by chemical analyses over the test period.
The 72h-ErC50 of 2-ethyl-4-(2,2,3-trimethylcyclopent-3-en-1-yl)but-2-en-1-ol to algae was predicted as 1.4 mg/L.
The 72h-NOErC of 2-ethyl-4-(2,2,3-trimethylcyclopent-3-en-1-yl)but-2-en-1-ol to algae was predicted as 0.49 mg/L.
This toxicity study is considered acceptable and satisfies the guideline requirements for growth inhibition of algae study.
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