2,2'-methylenebis[6-cyclohexyl-p-cresol]

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:

1991-10-14 - 1991-10-17

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

test procedure in accordance with national standard methods with acceptable restrictions

Remarks:

The study was conducted under GLP according to DIN 38 412 part 9 on the registered substance itself. The method is to be considered scientifically reasonable with minor deficiencies in documentation, but the available information allows the conclusion that the test was properly conducted. Also, the test item showed precipitation in the test vessels.

Qualifier:

according to guideline

Guideline:

other: DIN 38 412 Teil 9, Bestimmung der Hemmwirkung von Wasserinhaltsstoffen auf Grünalgen (Scenendesmus-Zellvermehrungs-Hemmtest) (L9), May 1989

Deviations:

no

GLP compliance:

yes

Analytical monitoring:

no

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Method: Weighing-in directly
- Controls: inoculum, in culture medium, and dilution water
- Evidence of undissolved material (e.g. precipitate, surface film, etc): precipitate as sediment and particles on surface

Test organisms (species):

Desmodesmus subspicatus (previous name: Scenedesmus subspicatus)

Details on test organisms:

TEST ORGANISM
- Common name: green algae
- Strain: Scenedesmus subspicatus CHODAT
- Source (laboratory, culture collection): Pflanzenphysiologisches Institut der Universität, 3400 Göttingen, Germany
- Method of cultivation: In laboratory for water biology (WV-Umweltschutz) in light cabinet (PVP) at 23 ± 2 °C and a photosynthetically effective radiant flux density of 120 Micro-Einstein / m² * s; weekly inoculation of stem cultures

ACCLIMATION
- Any deformed or abnormal cells observed: none noted

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

72 h

Post exposure observation period:

none

pH:

8.5 - 11.1

Nominal and measured concentrations:

0, 320, 1000 mg/L (nominal)

Details on test conditions:

TEST SYSTEM
- Test vessel: Erlenmeyer flask
- Material, size, headspace, fill volume: 300 ml total volume, 100 ml fill volume
- Initial cells density: 10,000 cells/ml
- Control end cells density: 771.000 cells/ml

GROWTH MEDIUM
- Standard medium used: according to chapter 12.1 of DIN 38 412 part 9

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: deionized water, additionally treated with Millipore system

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
- Determination of cell concentrations: Microcellcounter Sysmex F-300 (Digitana), daily
- Chlorophyll measurement: no

TEST CONCENTRATIONS
- Test concentrations: 0, 320, 1000 mg/ml

Reference substance (positive control):

no

Duration:

72 h

Dose descriptor:

EC10

Effect conc.:

> 1 000 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

biomass

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

> 1 000 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

biomass

Duration:

72 h

Dose descriptor:

EC10

Effect conc.:

> 1 000 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

> 1 000 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Details on results:

- Exponential growth in the control (for algal test): yes
- Observation of abnormalities (for algal test): none noted
- Any observations (e.g. precipitation) that might cause a difference between measured and nominal values: In all testing solutions unsolved fractions of the test item remained as sediment resp. swam on the surface of the test medium.
- Effect concentrations exceeding solubility of substance in test medium: 320, 1000 mg/L

Validity criteria fulfilled:

not specified

Conclusions:

The study was conducted under GLP according to DIN 38 412 part 9 on the registered substance itself. The method is to be considered scientifically reasonable with minor deficiencies in documentation, but the available information allows the conclusion that the test was in general properly conducted. Hence, the results can be considered as reliable to assess the effects of Phenol, 2,2'-methylenebis-(6-cyclohexyl-4-methyl) to aquatic organisms, here, green algae.
Taking into account the determined effect values after 72h with regard to growth rate and biomass, based on nominal concentrations, i.e. EC10 ≥ 1000 mg/L, and EC50 > 1000 mg/L, the test item does not need to be classified as hazardous to the aquatic environment according to Regulation (EC) No. 1272/2008, neither acute nor long-term.
As noted in the test report, the test item was not completely solved in any of the test solutions. This implies that the actual concentrations are below the nominal ones. Since no concrete numbers are available, a classification as aquatic chronic should be considered. Water solubility was determined as 0.034 mg/L, triggering hence classification as aquatic chronic cat. 4.

Executive summary:

In an 72 hour acute toxicity study, the cultures of Scenedesmus subspicatus CHODAT were exposed to Phenol, 2,2'-methylenebis-(6-cyclohexyl-4-methyl) at nominal concentrations of 0, 320, and 1000 mg/L under static conditions in accordance with the DIN 38 412 part 9. The EC₁₀and EC₅₀ values based on growth rate and biomass were >1000 mg/L (nominal).

There were no compound related phytotoxic effects noted.

This toxicity study is classified as acceptable.

Description of key information

Toxicity to algae: EC10 > 1000 mg/L, EC50 > 1000 mg/L (nominal) for Scenedesmus subspicatus CHODAT (DIN 38 412 part 9, static)

Key value for chemical safety assessment

EC50 for freshwater algae:

1 000 mg/L

EC10 or NOEC for freshwater algae:

1 000 mg/L

Additional information

The chosen endpoint is the only available study. It was conducted under GLP according to DIN 38 412 part 9 on the registered substance itself. The method is to be considered scientifically reasonable with minor deficiencies in documentation, but the available information allows the conclusion that the test was in general properly conducted. Hence, the results can be considered as reliable to assess the effects of Phenol, 2,2'-methylenebis-(6-cyclohexyl-4-methyl) to aquatic organisms, here, green algae.

The results were, based on nominal concentrations, EC10 >1000 mg/L, and EC50 > 1000 mg/L, which do not trigger classification as hazardous to the aquatic environment according to Regulation (EC) No. 1272/2008, neither acute nor long-term.

Taking into account the determined water solubility of 0.034 mg/L, the safety net classification as acquatic chronic 4 is triggered.

There is no indication that the study and hence the result and conclusions are not reliable, and so no additional data is required, no data gaps were identified.