trans-(5RS,6SR)-6-amino-2,2-dimethyl-1,3-dioxepan-5-ol

Toxicity to aquatic algae and cyanobacteria

Link to relevant study record(s)

Reference

Endpoint:

effects on growth of green algae

Type of information:

experimental study

Adequacy of study:

key study

Study period:

Jul - Sep 1994

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 201 (Freshwater Alga and Cyanobacteria, Growth Inhibition Test)

Version / remarks:

1984

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

no

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Method: For the stock solution 1.254 g were dissolved in 500 mL demineralized water. This solution was used for the highest concentration.
- Controls: 1 control, six replicates
- Concentration of vehicle in test medium (stock solution and final test solution(s) or suspension(s) including control(s)): This stock solution was diluted to arrive at the test concentrations 1000 mg/L, 500 mg/L and 250 mg/L. 80 mL of the respective solutions were filled into the test vessels.
- Test concentration separation factor: 2

Test organisms (species):

Desmodesmus subspicatus (previous name: Scenedesmus subspicatus)

Details on test organisms:

TEST ORGANISM
- Common name: green algae
- Strain: Non-axenic strain
- Source: obtained from '"Sammlung von Algenkulturen, Universität Göttingen", Germany.
- Age of inoculum (at test initiation): 72 h
- Method of cultivation: The preculture was incubated for 72 hours in an incubator shaker apparatus at 23 °C After the incubation period the cell concentration of the algae was measured, and the pre-culture was diluted to 10000 cells/ mL with demineralized water.

ACCLIMATION
- Acclimation period: 3 days
- Culturing media and conditions (same as test or not): conditions are identical
- Any deformed or abnormal cells observed: None

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

72 h

Test temperature:

23 °C

pH:

8.2 to 10.2

Details on test conditions:

TEST SYSTEM
- Type of flow-through (e.g. peristaltic or proportional diluter):
- Renewal rate of test solution (frequency/flow rate):
- Initial cells density: 10000/ mL
- Control end cells density: 64280 cells/ mL (highest concentration)
- No. of organisms per vessel: 10000
- No. of vessels per concentration (replicates): 3
- No. of vessels per control (replicates): 6

GROWTH MEDIUM
- Standard medium used: yes

EFFECT PARAMETERS MEASURED
- Determination of cell concentrations: Cell densities are measured in a microcell counter. Cell densities are recorded at 24-hour intervals.

Reference substance (positive control):

no

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

1 620 mg/L

Nominal / measured:

meas. (initial)

Conc. based on:

test mat.

Basis for effect:

cell number

Key result

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

814 mg/L

Nominal / measured:

meas. (initial)

Conc. based on:

test mat.

Basis for effect:

biomass

Details on results:

- Exponential growth in the control (for algal test): yes
- Any stimulation of growth found in any treatment: No
- Other: The EbC50 and ErC50 values differed by a factor of approximately 2. The guideline does not provide information on whether the biomass or the growth rate is more relevant for the interpretation of the data. The pH increased in the control vessels to a significant degree, which can be assumed to be caused by the large growth of the algae population. The changes in the determined pH-range were unavoidable and were not considered to have an impact on the conduct of the test and the results were not influenced.

 

Validity criteria for the measurement of the algae toxicity

Target condition according to guideline:	Actual condition according to the study:	Validity criteria met:
The biomass in the control cultures should have increased exponentially by a factor of at least 16 within the 72-hour test period. This corresponds to a specific growth rate of 0.92 day^-1. This criterion may not be met when species that grow slower than those listed in Annex 2 of OECD TG 201 are used. In this case, the test period should be extended to obtain at least a 16-fold growth in control cultures, while the growth has to be exponential throughout the test period. The test period may be shortened to at least 48 hours to maintain unlimited, exponential growth during the test as long as the minimum multiplication factor of 16 is reached.	During the test, the biomass in the control increased exponentially by a factor >16	Yes
The mean coefficient of variation for section-by-section specific growth rates (days 0-1, 1-2 and 2-3, for 72-hour tests) in the control cultures must not exceed 35%. This criterion applies to the mean value of coefficients of variation calculated for replicate control cultures.	The mean coefficent of variation for section-by-section specific growth rates in the control was <4%	Yes
The coefficient of variation of average specific growth rates during the whole test period in replicate control cultures must not exceed 7% in tests with Pseudokirchneriella subcapitata and Desmodesmus subspicatus. For other less frequently tested species, the value should not exceed 10%.	The coefficent of variation of average specific growth rates (0-72h) in the control was <2%	Yes
The cultures should be maintained at a temperature in the range of 21 to 24°C, controlled at ± 2°C.	The cultures were maintained at a temperature of 23 °C	Yes

Validity criteria fulfilled:

yes

Remarks:

See 'Any other information on results incl. tables'.

Conclusions:

The test substance has an inhibitory, concentration-dependent effect on the growth of Scenedesmus subspicatus. The EbC50 (biomass) was 814 mg/L, and the ErC50 (growth rate) was 1620 mg/L.

Executive summary:

The study was performed to assess adverse effects of the test substance on the growth (=increase in cell density) and the growth rate (=rate of increase in cell density with time) of the planktonic freshwater algal species Desmodesmus subspicatus over several generations. The study was conducted to the OECD Guideline for Testing of Chemicals No 201 'Alga, Growth Inhibition Test'. Exponentially growing algal cells were exposed for a period of 72 hours of the test substance dissolved in water. The cell densities were measured at 24-hour intervals. Inhibition of the algal population was measured as reduction in growth (index b) and growth rate (index r), relative to control cultures grown under identical conditions. Recovery rates correspond to 97.2% of nominal values at 0 hours and correspond to 97.3% of nominal values at 72 hours, respectively. The test substance produced a clear inhibitory effect on the growth of the test organism that was related to test substance concentration. The EbC50 (biomass) was 814 mg/L and the ErC50 (growth rate) was 1620 mg/L.

Description of key information

The study was performed to assess adverse effects of the test substance on the growth (=increase in cell density) and the growth rate (=rate of increase in cell density with time) of the planktonic freshwater algal species Desmodesmus subspicatus over several generations. The study was conducted to the OECD Guideline for Testing of Chemicals No 201 'Alga, Growth Inhibition Test'. Exponentially growing algal cells were exposed for a period of 72 hours of the test substance dissolved in water. The cell densities were measured at 24-hour intervals. Inhibition of the algal population was measured as reduction in growth (index b) and growth rate (index r), relative to control cultures grown under identical conditions. Recovery rates correspond to 97.2% of nominal values at 0 hours and correspond to 97.3% of nominal values at 72 hours, respectively. The test substance produced a clear inhibitory effect on the growth of the test organism that was related to test substance concentration. The EbC50 (biomass) was 814 mg/L and the ErC50 (growth rate) was 1620 mg/L.

Key value for chemical safety assessment

EC50 for freshwater algae:

1 620 mg/L