Reaction mass of cyclohexanol and cyclohexanone

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

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

study well documented, meets generally accepted scientific principles, acceptable for assessment

Remarks:

Test performance meets generally accepted ecotoxicological standards. A gas tight system was used to prevent volatility losses. Care was taken to prevent CO2 limitation. Substance concentration was measured.

Principles of method if other than guideline:

Acute toxicity test with green algae. The CO2 concentration in the gas phase of the test vessel was determined using GC/TCD (Thermal conductivity detector).

GLP compliance:

no

Analytical monitoring:

yes

Details on sampling:

- Sampling: The effective concentrations of the compounds in the alga culture were determined using GC/ECD (electron capture detector) analysis of extracts at the end of the assay.

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION
- Eluate: no
- Controls: yes, a blank control and a toxicity control was tested in parallel
- Evidence of undissolved material (e.g. precipitate, surface film, etc): no
- To test non-volatile compounds, weII-defined stock solutionstration in distilled water and dilution series were prepared and added to an equal volume of double concentrated test medium. To run tests with volatile compounds, saturated solutions in growth medium were prepared. Defined aliquots of these solutions were added to the medium.

Test organisms (species):

Chlamydomonas reinhardtii

Details on test organisms:

TEST ORGANISM
- Common name: Green Alga
- Strain: 11-32a
- Source (laboratory, culture collection): SAG
- Age of inoculum (at test initiation): 7 days
- Method of cultivation: static in bipartite vessels, gas tight


ACCLIMATION
- Culturing media and conditions (same as test or not): Precultures and test cultures were grown in the medium for unicellular algae according to Kuhl (1962). Incubation of all cultures was done in an Orbital Incubator (Gallenkamp). The cultures were shaken permanently with a frequency of 120 rpm. They were illuminated from above with 130 µE/m2 s-1 without light dark cycle. The temperature was maintained at 20±1°C.

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

72 h

Reference substance (positive control):

yes

Remarks:

copper sulphate CuSO4

Duration:

72 h

Dose descriptor:

EC10

Effect conc.:

3.56 mg/L

Nominal / measured:

meas. (not specified)

Conc. based on:

test mat.

Basis for effect:

growth rate

Remarks on result:

other: 0.4-7.93 (C.I. 95%)

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

32.9 mg/L

Nominal / measured:

meas. (not specified)

Conc. based on:

test mat.

Basis for effect:

growth rate

Remarks on result:

other: 17.7-85.6 (C.I. 95%)

Executive summary:

An experimental study according to was conducted to assess the toxicity of cyclohexanone to aquatic algae. The test organism Chlamydomonas reinhardtii was exposed to cyclohexanone for 72 h. The EC50 after 72 h was 32.9 mg/l and the EC10 3.56 mg/l. As Basis for the effect the growth rate was used. The test performance meets generally accepted ecotoxicological standards. A gas tight system was used to prevent volatility losses. Care was taken to prevent CO2 limitation. The Substance concentration was measured.

Description of key information

The values for the reaction mass were derived from the values of the single components. The EC50 (72h) for cyclohexanone (32.9 mg/l) was lower than the value for cyclohexanol (>500 mg/l). Therefore, it is the more sensitive endpoint and was chosen to derive the EC50 and EC10 for the mixture. Assuming a worst-case scenario the EC50 (72h) for the reaction mass is 32.9 mg/l and the EC10 (72h) 3.56 mg/l.

 

Key value for chemical safety assessment

EC50 for freshwater algae:

32.9 mg/L

EC10 or NOEC for freshwater algae:

3.56 mg/L

Additional information

 

No experimental study with the mixture was conducted. Since there are reliable experimental studies for the single components of the mixture, the most sensitive value of both can be used to derive the value for the mixture assuming a worst-case scenario.

An experimental study according to DIN 38412 Part 9 was conducted to assess the toxicity of the single component cyclohexanol to aquatic algae. The test organism Desmodesmus subspicatus was exposed to the nominal concentrations 0.08, 0.03, 0.12, 0.49, 1.95, 7.81, 31.25, 125.0 and 500.0 mg/L for 96 h. The EC50 after 72 h was >500 mg/l and the NOEC 0.03 mg/l. After 96 h an EC50 of 483.82 mg/l was measured. As Basis for the effect the growth rate was used (BASF, 1988).

To assess the toxicity of cyclohexanone, as the second single component, to aquatic algae an experimental study according to was conducted. The test organism Chlamydomonas reinhardtii was exposed to cyclohexanone for 72 h. The EC50 after 72 h was 32.9 mg/l and the EC10 3.56 mg/l. As Basis for the effect the growth rate was used. The test performance meets generally accepted ecotoxicological standards. A gas tight system was used to prevent volatility losses. Care was taken to prevent CO2 limitation. The Substance concentration was measured (Brack & Rottler 1994).

The EC50 (72h) for cyclohexanone (32.9 mg/l) was lower than the value for cyclohexanol (>500 mg/l). Therefore, it is the more sensitive endpoint and is chosen to derive the EC50 and EC10 for the mixture. Assuming a worst-case scenario the EC50 (72h) for the reaction mass is 32.9 mg/l and the EC10 (72h) 3.56 mg/l.