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

Short-term toxicity to aquatic invertebrates

Link to relevant study record(s)

Reference

Endpoint:

short-term toxicity to aquatic invertebrates

Type of information:

experimental study

Adequacy of study:

key study

Study period:

1991-09-17 - 1991-09-19

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 a guideline issued by the German Environmental Protection Agency ("Bestimmung der Schwimmunfähigkeit beim Wasserfloh (determination of immobilization of daphnids) -Daphnia magna-" (EC 0, EC 50, EC 100; 24 Stunden; statisches System) Verfahrensvorschlag: Umweltbundesamt Berlin, Stand Mai 1984) on the registered substance itself. The method is to be considered scientifically reasonable with minor deficiencies in documentation. Also, there is a notable deviation of the analytically determined concentrations (via DOC content) from the nominal ones. However, this deviation is documented and allows an adapted assessment.

Qualifier:

according to guideline

Guideline:

other: "Bestimmung der Schwimmunfähigkeit beim Wasserfloh (determination of immobilization of daphnids) -Daphnia magna-" (EC 0, EC 50, EC 100; 24 Stunden; statisches System) Verfahrensvorschlag: Umweltbundesamt Berlin, Stand Mai 1984

Deviations:

no

GLP compliance:

yes

Analytical monitoring:

yes

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Method: Weighing-in directly
- Evidence of undissolved material (e.g. precipitate, surface film, etc): yes

Test organisms (species):

Daphnia magna

Details on test organisms:

TEST ORGANISM
- Common name: "Wasserfloh" (Daphnia)
- Strain: Daphnia magna Straus, parthenogenetic females, Klonzucht des Bundesgesundheitsamtes Berlin
- Source: Laborzucht der (Laboratory breeding of) Bayer AG Leverkusen
- Age at study initiation (mean and range, SD): 6-24 h

Test type:

static

Water media type:

freshwater

Limit test:

yes

Total exposure duration:

48 h

Post exposure observation period:

no data

Hardness:

15.1°dH

Test temperature:

20.3°C - 20.6°C

pH:

7.6-8.0

Dissolved oxygen:

8.2 - 8.2 mg/L

Nominal and measured concentrations:

Nominal: 0, 1000 mg/L
Measured: 0, 25.4 mg/L

Details on test conditions:

TEST SYSTEM
- Test vessel: cylindric
- Material, size, headspace, fill volume: diameter 4 cm, height 6.5 cm, 20 ml fill volume
- Aeration: not aerated
- No. of organisms per vessel: 10
- No. of vessels per concentration (replicates): 2

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: synthetic dilution water according to Elendt (1990)
- Culture medium different from test medium: No

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) : Number of immobilized Daphnids after 24h and 48h.

TEST CONCENTRATIONS
- Test concentrations: 0, 1000 mg/L

Reference substance (positive control):

yes

Remarks:

Potassium dichromate

Duration:

24 h

Dose descriptor:

EC0

Effect conc.:

>= 1 000 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mobility

Duration:

24 h

Dose descriptor:

EC50

Effect conc.:

> 1 000 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mobility

Duration:

48 h

Dose descriptor:

EC0

Effect conc.:

>= 1 000 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mobility

Key result

Duration:

48 h

Dose descriptor:

EC50

Effect conc.:

> 1 000 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mobility

Duration:

48 h

Dose descriptor:

EC0

Effect conc.:

>= 25.4 mg/L

Nominal / measured:

meas. (not specified)

Conc. based on:

other: recalculation from DOC measurement

Basis for effect:

mobility

Remarks on result:

other: DOC determined after 48h test duration

Duration:

48 h

Dose descriptor:

EC50

Effect conc.:

> 25.4 mg/L

Nominal / measured:

meas. (not specified)

Conc. based on:

other: recalculation from DOC measurement

Basis for effect:

mobility

Remarks on result:

other: DOC determined after 48h test duration

Details on results:

- Behavioural abnormalities: no changes in mobility
- Any observations (e.g. precipitation) that might cause a difference between measured and nominal values: A turbid suspension was observed upon preparation of the test solution.
- Effect concentrations exceeding solubility of substance in test medium: 1000 mg/kg

Results with reference substance (positive control):

- Other: See tables

Validity criteria fulfilled:

yes

Remarks:

controls gave the appropriate results

Conclusions:

The study was conducted under GLP according to a guideline issued by the German Environmental Protection Agency ("Bestimmung der Schwimmunfähigkeit beim Wasserfloh (determination of immobilization of daphnids) -Daphnia magna-" (EC 0, EC 50, EC 100; 24 Stunden; statisches System) Verfahrensvorschlag: Umweltbundesamt Berlin, Stand Mai 1984) on the registered substance itself. The method is to be considered scientifically reasonable with minor deficiencies in documentation. 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, Daphnia magna Straus. Taking into account the determined effect values after 48h, based on nominal concentrations, i.e. EC0 ≥ 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.
A substance-specific analysis and hence specific verification of the actual concentrations was not performed. As already mentioned, via DOC analysis the solved fraction of the test item as well as possible metabolites were determined. These DOC values were 0 resp. 21 mg/L, corresponding to 25.4 mg/L of Phenol, 2,2'-methylenebis-(6-cyclohexyl-4-methyl). Hence, the analytical EC0 can be considered as ≥ 25.4 mg/L. Considering the analytical concentrations and available endpoints for an acute toxicity study, the substance does not need to be classified as acutely hazardous to daphnids nor as aquatic chronic cat. 1, or 2.
Taking into account however the water solubility of 0.034 mg/L at 20°C (GLP study, shake flask method), the determined EC0 is above the water solubility of the substance. Taking furthermore into account the fact that the substance is not readily biodegradable (0% (ThOD) in 28 days, OECD TG 301 F) and a logPow > 4.3 (GLP, partition coefficient determination), the safety net classification as aquatic chronic category 4 is triggered.
In summary, on the grounds of the obtained results, Phenol, 2,2'-methylenebis-(6-cyclohexyl-4-methyl) does not need to be classified as acutely toxic according to Regulation (EC) No. 1272/2008, based on nominal concentrations, and would need to be classified as aquatic chronic category 4 based on the estimated actual ones considering water solubility, logPow and lacking biodegradation.

Executive summary:

The 48h acute toxicity of Phenol, 2,2'-methylenebis-(6-cyclohexyl-4-methyl) to Daphnia magna Straus was studied under static conditions. Daphnids were exposed to control and test chemical at a nominal concentration of 1000 mg/L for 48h. Immobilization was observed daily. The 48h EC₅₀was >1000 mg/L (nominal), corresponding to analytical 25.4 mg/L (DOC determination).

Based on the results of this study, Phenol, 2,2'-methylenebis-(6-cyclohexyl-4-methyl) would need to be classified as aquatic chronic category 4 according to Regulation (EC) No. 1272/2008.

This study is classified as acceptable and satisfies the guideline requirements for an acute toxicity study with freshwater invertebrates.

Description of key information

Short-term toxicity to aquatic invertebrates: EC50(48h) > 1000 mg/l, EC0(48h) ≥ 1000 mg/l (nominal) for Daphnia magna (UBA Vorschrift, determination of immobilization of daphnids, May 1984, static, GLP)

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates

Effect concentration:

1 000 mg/L

Additional information

The chosen endpoint is the only available study. The study was conducted under GLP according to a guideline issued by the German Environmental Protection Agency ("Bestimmung der Schwimmunfähigkeit beim Wasserfloh (determination of immobilization of daphnids) -Daphnia magna-" (EC 0, EC 50, EC 100; 24 Stunden; statisches System) Verfahrensvorschlag: Umweltbundesamt Berlin, Stand Mai 1984) on the registered substance itself. The method is to be considered scientifically reasonable with minor deficiencies in documentation. 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, Daphnia magna Straus. Taking into account the determined effect values after 48h, based on nominal concentrations, i.e. EC0≥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.

Taking into account however the water solubility of 0.034 mg/L at 20°C (GLP study, shake flask method), the determined EC0 is above the water solubility of the substance. Taking furthermore into account the fact that the substance is not readily biodegradable (0% (ThOD) in 28 days, OECD TG 301 F) and a logPow > 4.3 (GLP, partition coefficient determination), the safety net classification as aquatic chronic category 4 is triggered.

In summary, on the grounds of the obtained results, Phenol, 2,2'-methylenebis-(6-cyclohexyl-4-methyl) does not need to be classified as acutely toxic according to Regulation (EC) No. 1272/2008, based on nominal concentrations, and would need to be classified as aquatic chronic category 4 based on the estimated actual ones considering water solubility, logPow and lacking biodegradation.