N-[(triethoxysilyl)methyl]cyclohexylamine

Toxicity to aquatic algae and cyanobacteria

Administrative data

Endpoint:

toxicity to aquatic algae and cyanobacteria

Type of information:

experimental study

Adequacy of study:

key study

Study period:

April 26 - Aug 12, 2004

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2004

Report date:

2004

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 201 (Alga, Growth Inhibition Test)

Version / remarks:

adopted June 7, 1984

Deviations:

no

GLP compliance:

yes

Test material

Test material information

Constituent 1

Reference substance name:

-

EC Number:

454-780-6

EC Name:

-

Cas Number:

27445-54-1

Molecular formula:

Hill formula: C12H27NO2Si CAS formula: C12H27NO2Si

IUPAC Name:

Cyclohexyl-((diethoxy-methyl-silanyl)-methyl)-amine

Test material form:

liquid

Sampling and analysis

Analytical monitoring:

yes

Test solutions

Vehicle:

no

Details on test solutions:

Since the test item hydrolyses in water very quickly, in the present test the hydrolysis products were tested, according to the draft guidance document on aquatic toxicity testing of difficult substances. Therefore, the highest concentration of 100 mg/I was prepared by dosing 99,5 mg test item into 995 mL test water and stirred for about 24 hours at room temperature. Thus, the main part of the test item were hydrolysis products.
Then, adequate volumes of the stock solution were diluted with test water to prepare the test concentrations.

Test organisms

Test organisms (species):

Desmodesmus subspicatus (previous name: Scenedesmus subspicatus)

Details on test organisms:

Species:
Desmodesmus subspicatus CHODAT, Strain No. 86.81 SAG
Origin:
The algae were supplied by the "Sammlung von Algenkulturen, Pflanzenphysio10gisches Institut der Universitiit G6ttingen", 37073 G6ttingen, Germany.
Breeding Conditions:
The algae were cultivated in the laboratories of IBACON understandardised conditions according to the test guidelines.
Toxic Standard:
For the evaluation of the quality of the algae and the experimental conditions the substance potassium dichromate p.A. is tested at least twice a year to demonstrate satisfactory test conditions

Study design

Test type:

static

Water media type:

other: Reconstituted water: In deionised water (conductivity < 5 µScm-1) analytical grade salts were added to following nominal concentrations:

Limit test:

no

Total exposure duration:

72 h

Test conditions

Hardness:

0.24 mmol/L (= 24 mg/L) as CaCO3

Test temperature:

23°C

pH:

pH 8.0 to 8.2 at test start
pH 8.3 to 10.5 at test end
This increase of the pH during the test was obviously caused by the CO2-consumption of the algae due to their rapid growth respectively their high densities (although the test media have been intensively stirred)

Salinity:

not applicable

Conductivity:

< 5 µScm-1

Nominal and measured concentrations:

0.05, 0.19, 0.67, 2.33, 8.16, 28.57 and 100 mg test item/L and a control (test water was used without addition of the test item)
At the start ofthe test in the analysed test media 86 % ofthe nominal test concentrations were found. After 72 hours test duration 87 % of the nominal values were determined. Thus, during the test period of 72 hours the algae were exposed to 86 % of the nominal values. Therefore, all reported results are related to nominal concentrations of the test item.

Details on test conditions:

Test Conditions:
- 23°C water temperature
- Light Regime: continuous illumination
- Light Intensity: 7780 Lux (mean value), range: 7470 to 7990 Lux (minimum and maximum value of measurements at 6 places distributed over the experimental area at the surface of the test media). This illumination was achieved by fluorescent tubes installed above the test flasks.
Test Units:
- Erlenmeyer flasks of 50 mL volume with 50 mL test medium. Each test unit was uniquely identified with the study number, treatment and replicate number.
Course of the test:
- Introduction of Algae: The test was started (0 hours) by inoculation of a biomass of 10000 algal cells per mL test medium. These cells were taken from an exponentially growing pre-culture, which was set up 4 days prior to the test start at the same conditions as in the test.
- The test was performed with three replicates per test concentration and six replicates in the control. Volumes of 50 mL algal suspension per replicate were continuously stirred by magnetic stirrers in 50 mL Erlenmeyer flasks. They were covered with glass dishes. The flasks were incubated in a water bath.
- Additionally, one replicate per test concentration was prepared without algae to provide as "blank" for the spectrophotometrical measurements. The additional replicates were incubated under the same conditions as described above. These blank values were subtracted from the absorption measured in the samples containing algae in order to eliminate absorption caused by test item.

Reference substance (positive control):

no

Results and discussion

Effect concentrations

Effect concentrations 1

Key result

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

40.71 mg/L

Nominal / measured:

nominal

Conc. based on:

other: test mat. / but exposure is to hydrolysis products

Basis for effect:

growth rate

Effect concentrations 2

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

2.33 mg/L

Nominal / measured:

nominal

Conc. based on:

other: test mat. / but exposure is to hydrolysis products

Basis for effect:

growth rate

Details on results:

At the nominal concentration of 0.05 to 8.16 mg/L no remarkable observations were made. At the two highest test concentrations of nominal 28.57 and 100 mg/L the test medium was turbid after 72 hours.
At the microscopic examination of the shape of the algal cells after 72 hours test period no difference was observed between the algae growing in the test concentration of nominal 100 mg test itemIL and the algal cells in the control. Thus, the shape of the algal cells growing at least up to this test concentration was obviously not affected.

Applicant's summary and conclusion

Validity criteria fulfilled:

yes

Conclusions:

A 72 h EC50 of 40.71 mg/L, and a 72 h NOEC of 2.33 mg/L have been determined for the effects of the test substance on growth rate of Desmodesmus subspicatus. The results are expressed relative to nominal concentrations of the test substance. However, the substance is subject to rapid hydrolysis and under the test conditions it is therefore likely that exposure will have been to its hydrolysis products.