Octan-2-one

Toxicity to aquatic algae and cyanobacteria

Link to relevant study record(s)

Reference

Endpoint:

toxicity to aquatic algae and cyanobacteria

Type of information:

experimental study

Adequacy of study:

key study

Study period:

12-05-2017 - 15-05-2017

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Justification for type of information:

Experimental test result performed using standard test guidelines

Qualifier:

according to guideline

Guideline:

OECD Guideline 201 (Alga, Growth Inhibition Test)

GLP compliance:

no

Analytical monitoring:

not specified

Vehicle:

yes

Details on test solutions:

The solution (100 mg/L) was prepared by dissolving clear yellow coloured liquid in DMSO/ OECD growth medium.

Test organisms (species):

Desmodesmus subspicatus (previous name: Scenedesmus subspicatus)

Details on test organisms:

TEST ORGANISM
- Strain: 86.81 SAG
- Source (laboratory, culture collection): Institute of botany of the ASCR
- Initial biomass concentration: 5x10(3) cells /ml
- Method of cultivation: No data available

ACCLIMATION - No data available

Test type:

static

Water media type:

freshwater

Limit test:

yes

Total exposure duration:

72 h

Remarks on exposure duration:

±1 hour

Hardness:

not specified

Test temperature:

23±2°C

pH:

Without adjustment
The sample concentration at 100 mg/L: pH=8.2 changed to pH=8.5 during the tests
Control: pH=8.3 did not changed during the test

Dissolved oxygen:

not specified

Salinity:

not specified

Conductivity:

not specified

Nominal and measured concentrations:

0 and 100 mg/L

Details on test conditions:

TEST SYSTEM
- Test vessel: 50/ 100 ml Glass vessel
- Type (delete if not applicable): closed (with air permeable stopper)
- Sample volume: 15 ml
- Initial cells density: 5x10(3) cells/ml
- No. of vessels per concentration (replicates): 3

GROWTH MEDIUM
- Standard medium used: yes

OTHER TEST CONDITIONS
- Adjustment of pH: No
- Photoperiod: Continuous
- Light intensity and quality: 6000-8000 lx

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
- Determination of cell concentrations: microscope with counting chamber Cyrus I or electronic particle counter.
- Other: ErC50 was calculated using non-linear regression by the software Prism 4.0

Reference substance (positive control):

yes

Remarks:

Potassium dichromate (K2Cr2O7)

Key result

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

> 100 mg/L

Nominal / measured:

meas. (not specified)

Conc. based on:

test mat.

Basis for effect:

growth rate

Results with reference substance (positive control):

Results with reference substance valid
- EC50: 0.75 mg/L

Reported statistics and error estimates:

Statistics:
p= 0.360
Significant difference= no

Validity criteria fulfilled:

yes

Conclusions:

The median effective concentration (EC50) for the test substance, in Desmodesmus subspicatus was determined to be >100 mg/L on the basis of effects on growth rate in a 72 hour study.

Executive summary:

Aim of this study was to evaluate the nature of chemical test chemical when comes in contact with the test organism Desmodesmus subspicatus (previous name: Scenedesmus subspicatus). Test was conducted according to the OECD guideline 201. The solution (100 mg/L) was prepared by dissolving clear yellow coloured liquid in OECD growth medium.With the test substance one positive control Potassium dichromate (K2Cr2O7) was also run simultaneously. After the exposure of chemical, effect concentration EC50 was calculated using nonlinear regression by the software Prism 4.0. Effect on the growth of algae was determine after an exposure period of 72 hrs.

The median effective concentration (EC50) for the test substance in algae was determined to be >100 mg/L on the basis of growth rate inhibition effects in a 72 hour study. Based on the EC50 value, which indicates that the substance is likely to be non-hazardous to aquatic algae and cannot be classified as as per the CLP classification criteria.

Description of key information

Toxicity to aquatic algae and cyanobacteria:

Aim of this study was to evaluate the nature of chemical test chemical when comes in contact with the test organism Desmodesmus subspicatus (previous name: Scenedesmus subspicatus). Test was conducted according to the OECD guideline 201.The solution (100 mg/L) was prepared by dissolving clear yellow coloured liquid in OECD growth medium.With the test substance one positive control Potassium dichromate (K2Cr2O7) was also run simultaneously. After the exposure of chemical, effect concentration EC50 was calculated using nonlinear regression by the software Prism 4.0. Effect on the growth of algae was determine after an exposure period of 72 hrs.

The median effective concentration (EC50) for the test substance in algae was determined to be >100 mg/L on the basis of growth rate inhibition effects in a 72 hour study. Based on the EC50 value, which indicates that the substance is likely to be non-hazardous to aquatic algae and cannot be classified as as per the CLP classification criteria.

Key value for chemical safety assessment

EC50 for freshwater algae:

100 mg/L

Additional information

Toxicity to aquatic algae and cyanobacteria:

Various experimental study for the target compound were reviewed for toxicity to aquatic algae and cyanobacteria end point which are summarized as below:

 

In an experimental key study,aim of this study was to evaluate the nature of chemical test chemical when comes in contact with the test organism Desmodesmus subspicatus (previous name: Scenedesmus subspicatus). Test was conducted according to the OECD guideline 201.The solution (100 mg/L) was prepared by dissolving clear yellow coloured liquid in OECD growth medium.With the test substance one positive control Potassium dichromate (K2Cr2O7) was also run simultaneously. After the exposure of chemical, effect concentration EC50 was calculated using nonlinear regression by the software Prism 4.0. Effect on the growth of algae was determine after an exposure period of 72 hrs.

The median effective concentration (EC50) for the test substance in algae was determined to be >100 mg/L on the basis of growth rate inhibition effects in a 72 hour study. Based on the EC50 value, which indicates that the substance is likely to be non-hazardous to aquatic algae and cannot be classified as as per the CLP classification criteria.

While in supporting study, short term toxicity to Pseudokirchneriella subcapitata study was carried out for 48 hrs . The test chemical used for the study was 99% pure. The conc. of test chemical 2-Octanone(CAS no. 111-13-7)used for the study was in the range of 10.3 – 49.4 mg/l. Stock solutions of test chemical was prepared in foil-wrapped glass containers. The test organism used for the study is Pseudokirchneriella subcapitata (formerly known as Selenastrum capricornutum, UTEX 1648). Before starting the experiment, stock solution was freshly prepared and its concentration was analyzed using a HPLC analyzer. The alga Pseudokirchneriella subcapitata(formerly known as Selenastrum capricornutum, UTEX 1648) was grown in a 4-Ltransparent chemostat incubator. The growth medium wascontinuously supplied by a variable-speed pump. Air agitation was used to achieve adequate mixing. The chemostatreactors were placed in a constant-temperature room at24±1°C. Light intensity was set at 65mEm-2s-1(±10%).Growth medium composition is basically the same as that described by the EPA bottle technique. However, NaNO3, K2HPO4, and EDTA contents were reduced to 12.75, 0.52 mg/L, and 30mg/L, respectively. The dilution rate (D) for the chemostat was set at 0.25/day. Toxicity testing was conducted after the algal incubator has reached the steady state by transferring adequate amounts of algal suspension, dilution water (with growth medium), and test chemical into 300-mL BOD bottles. The BOD bottles were completely filled up with no headspace left. Water seal was provided to ensure a closed test environment. The bottles were then placed on an orbital shaker operated at 100 rpm. Temperature and light intensity used for the study was 24 ± 1°C and 65 µEm-2s-1(± 10%). After 48 hrs of test duration, the EC50 value was calculated based on the dissolved oxygen production and algal growth rate.

In the toxicity experiment, the dilution water was stripped by nitrogen gas to reduce the dissolved oxygen level. In addition, the N2 gas contained 0.5% carbon dioxide as an extra carbon source. The DO level at the beginning of the test was approximately 1–3 mg/L. The initial inoculated cell density in the test vessel was 15,000 cells/mL

Algal cell density was measured by electronic particle counting (Coulter Multisizer). Probit analyses were applied to obtain the concentration–response relationships and EC50 values. Based on the dissolved oxygen production by organism and growth rate of test organism Pseudokirchneriella subcapitata, the EC50 value was found to be 32.9 mg/l and 41.2 mg/l, respectively.

 

In a supporting study from peer reviewed journal , short term toxicity to Pseudokirchneriella subcapitata study was carried out for 48 hrs. The test organism used for the study is Pseudokirchneriella subcapitata, UTEX 1648. Before commencing the experiment, stock solution was freshly prepared and its concentration was analyzed using a HPLC (HPLC; 2996 Photodiode Array Detector; Waters, Milford, MA, USA). Algal inoculum was withdrawn from a chemostat operated under steady state and transferred into 300 ml, biochemical oxygen demand (BOD) test bottles together with dilution water (with growth medium) and test chemical. The BOD bottles were completely filled, with no headspace left. A water seal was provided to ensure a close-test environment. The BOD bottles were then placed on an orbital shaker operated at 100 rpm. Temperature and light intensity were kept at 24 ± 1°C and 65 µEm-2s-1 (±10%), respectively. After 48 hrs of test duration, the EC50 value was calculated algal growth rate. The inhibition rate on the net increase of algal cell density was calculated. Probit analysis was used for determining the EC50 values. The population density of the algae was determined using an electronic particle counter. Based on the cell density of test organism Pseudokirchneriella subcapitata, the EC50 value was found to be 32.20 mg/l.

 

Another short term toxicity to Pseudokirchneriella subcapitata study was carried out for 48 hrs . The test organism used for the study is Pseudokirchneriella subcapitata. The test chemical (2-Octanone) concentrations used in the study are in the form of nominal concentrations. Toxicity tests were conducted using the 300-ml biochemical oxygen demand (BOD) test bottles, with no headspace left. A water seal was provided to ensure a closed-test environment. All tests were conducted in triplicate with test duration of 48 h. Three different endpoints were used to analyze the toxic effects of various organic compounds: dissolved oxygen (DO) production, algal growth rate (GR), and the net production of algal cell density (final cell density-initial cell density, biopopulation). One-tail Dunnett’s procedure was applied for the estimation of NOEC and LOEC values at 5% level of significance. NOEC was defined as the toxicant concentration which caused no significant difference compared to the test controls, with respect to all test endpoints (i.e., DO production, growth rate, and biopopulation). The EC10 value was determined using the best-fit-model approach. Regression analyses were performed by using MINITAB (Ver14.2, MINITAB, StateCollege, PA, USA) to establish prediction models for NOEC and EC10. In addition to this, leave- one-out cross-validation was carried out to test the significance of each prediction model. Based on various effects such as biopopulation and dissolved oxygen production of test substance 2-octanone on Pseudokirchneriella subcapitata, the 48 hrs NOEC, LOEC, EC10 and EC50 value was found to be 10.3, 24.7, 21.3 and 32.2 mg/l, respectively.

 

Thus, based on the reported results for target chemical (study report and from peer reviewed journals), it can be observed that the EC50 value is found to be between 32.2 - > 100 mg/L. Although the data from peer reviewed journals indicate the substance to be low toxic to aquatic algae but considering the reliability and authenticity of the study report, the test substance is considered to be Not classified as per the CLP criteria.