4,4'-cyclohexylidenedi-o-cresol

Bioaccumulation: aquatic / sediment

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

bioaccumulation in aquatic species: fish

Data waiving:

exposure considerations

Justification for data waiving:

the study does not need to be conducted because direct and indirect exposure of the aquatic compartment to the substance is unlikely

Justification for type of information:

JUSTIFICATION FOR DATA WAIVING
Information requirement 9.3.2. (bioaccumulation in aquatic species) is waived on the basis of exposure-based waiving. More specifically - in accordance with Section 3 of REACH Annex XI, testing in accordance with Annex IX and X may be omitted on the basis of substance-tailored exposure-driven testing.
Exposure-based waiving is considered justified based on the following rationale:
• The registrant does not supply the substance (as a reacted monomer in polymers) to the EU and has never supplied the substance in unreacted form to the EU. Furthermore, there are no co-registrants and hence there is currently no substance supply to the EU;
• Previously, the registrant has only ever supplied the substance to the EU in the form of the substance being a reacted monomer in imported polymers. In this historic case, the substance was permanently embedded within the polymer matrix throughout its entire life cycle. Hence, there was no substance release (either to man or the environment) during its past life cycle. Indeed, it would not have been reasonable to expect that there would have been any substance exposure to workers, the general public or the environment following normal and reasonably foreseeable conditions of use. Furthermore, when the substance was previously supplied as a reacted monomer in polymers, the relevant polymers were handled according to the conditions set out in Article 18(4)(a) to (f) during all manufacturing and production stages including the waste management of the substance during these stages;
• The likelihood of depolymerization (and back-formation) of the polymer to the substance monomer is negligible;
• A hypothetical, worst-case exposure based on previous EU use of the polymer demonstrates the absence of or no significant exposure to the registered substance throughout the lifecycle of the polymer. This exposure assessment has been conducted even though the EU supply level for the substance is zero, even though the substance has only ever been supplied as a reacted monomer in previously imported polymers, and even though analysis of residual levels in the previously imported polymer have been determined to be below 0.1 %.
• There have never been any professional or consumer uses of the substance.

A more detailed justification of these points is included in the attached justification document. Please also refer to the various assessment reports as included in section 13.2.

Furthermore, in accordance with section 9.3.2 of Column 2 of REACH Annex IX, it is considered justified to omit the bioaccumulation in aquatic species since direct and indirect exposure of the aquatic compartment is unlikely. Since direct and indirect exposure of the aquatic compartment is unlikely, the use of vertebrate animals to further investigate this endpoint is therefore not considered to be ethical.

Additionally, although the log Kow value is very slightly above the log Kow ≤3 cut-off criterion given in Column 2 (experimental value 3.1), it is considered that the log Kow value is sufficiently low so as to suggest that the substance is not likely to bioaccumulate. Supporting data is also included to help address this endpoint. In a study performed according to OECD Test Guideline 305 C (Cyprinus carpio), 28-day bioconcentration factors (BCFs) of 86 and 73 L/kg were reported when DMBPC was tested at initial aqueous concentrations of 0.01 and 0.001 mg/L, respectively (Iizuka, 2003).

Overall, it is therefore considered justified to omit a study to obtain further information on bioaccumulation in aquatic species as included under section 9.3.2. of REACH Annex IX.

Reference 2

Endpoint:

bioaccumulation in aquatic species: fish

Type of information:

experimental study

Adequacy of study:

supporting study

Reliability:

4 (not assignable)

Rationale for reliability incl. deficiencies:

abstract

Remarks:

Only Abstract was translated to English so unable to provide/determine study details.

Qualifier:

according to guideline

Guideline:

OECD Guideline 305 C (Bioaccumulation: Test for the Degree of Bioconcentration in Fish)

Deviations:

no

GLP compliance:

not specified

Radiolabelling:

not specified

Details on sampling:

Samples of water and fish were analysed on study days 7, 14, 21, 26 and 28.

Vehicle:

not specified

Details on preparation of test solutions, spiked fish food or sediment:

no data

Test organisms (species):

Cyprinus carpio

Details on test organisms:

Average body weight: 2.15 ± 0.28 g
Average body length: 5.8 ± 0.4 cm

Route of exposure:

aqueous

Test type:

flow-through

Water / sediment media type:

natural water: freshwater

Total exposure / uptake duration:

4 wk

Hardness:

no data

Test temperature:

25.0 ± 0.7°C

pH:

no data

Dissolved oxygen:

6.7 – 7.4 mg/L

TOC:

no data

Salinity:

no data

Details on test conditions:

Test aquarium: Glass aquarium (50 L)
Flow rate: 648 L/day

Nominal and measured concentrations:

0.01 and 0.001 mg/L (Nominal)

Reference substance (positive control):

not specified

Details on estimation of bioconcentration:

no data

Lipid content:

4 %

Time point:

start of exposure

Lipid content:

4.2 %

Time point:

end of exposure

Type:

BCF

Value:

86

Basis:

not specified

Calculation basis:

steady state

Remarks on result:

other: A steady state was established on the 14th day and thereafter

Remarks:

Conc.in environment / dose:0.01 mg/L

Type:

BCF

Value:

73

Basis:

not specified

Calculation basis:

steady state

Remarks on result:

other: A steady state was established on the 14th day and thereafter

Remarks:

Conc.in environment / dose:and 0.001 mg/L

Details on results:

Appearance of test fish was normal by aquarium-side observations.

Bioconcentration factors (BCF)

Exposure Level (mg/L)	Exposure period
	7 days	14 days	21 days	26 days	28 days
0.01	31	101	78	69	90
	15	94	95	89	72
0.001	49	60	71	65	95
	31	58	73	73	94

 

Validity criteria fulfilled:

not specified

Conclusions:

The steady-state bioconcentration factors of DMBPC (BCF 95) were 86 in Level 1 (0.01 mg/L) and 73 in level 2 (0.001 mg/L).

Executive summary:

The potential of the test substance to bioaccumulate was investigated in a study conducted in accordance with the standardised guideline OECD 305 C.

DMBPC was tested at initial aqueous concentrations of 0.01 and 0.001 mg/L in common carp (Cyprinus carpio) for 28 days. The test was carried out in freshwater under flow-through conditions at a flow rate of 648 L/day. A steady state was established on the 14th day and thereafter.

Samples of water and fish were analysed on study days 7, 14, 21, 26 and 28. The concentrations of DMBPC were determined by HPLC. The lipid content was determined to be 4 and 4.2 % at the start and end of exposure, respectively.

The steady-state bioconcentration factors of DMBPC (BCF 95) were 86 in Level 1 (0.01 mg/L) and 73 in level 2 (0.001 mg/L). These BCFs indicate that DMBPC has a low potential to bioaccumulate/bioconcentrate.

Description of key information

The endpoint bioaccumulation in aquatic species is waived in accordance with Section 3 of REACH Annex XI (substance-tailored exposure-driven testing) due to a demonstrable lack of exposure to the substance in the EU to either man or the environment.

 

In accordance with column 2 of REACH Annex IX (information requirement 9.3.2) is additionally waived since direct and indirect exposure of the aquatic compartment is unlikely.

 

Additionally, although the log Kow value is very slightly above the log Kow ≤3 cut-off criterion given in Column 2 (experimental value 3.1), it is considered that the log Kow value is sufficiently low so as to suggest that the substance is not likely to bioaccumulate. Supporting data is also included to help address this endpoint. In a study performed according to OECD Test Guideline 305 C (Cyprinus carpio), 28-day bioconcentration factors (BCFs) of 86 and 73 L/kg were reported when DMBPC was tested at initial aqueous concentrations of 0.01 and 0.001 mg/L, respectively.

 

Overall, it is therefore considered justified to omit a study to obtain further information on bioaccumulation in aquatic species as included under section 9.3.2. of REACH Annex IX.

Key value for chemical safety assessment

BCF (aquatic species):

86 L/kg ww

Additional information

In a supporting study performed according to OECD Test Guideline 305 C testing common carp (Cyprinus carpio), 28-d bioconcentration factors (BCFs) of 86 and 73 L/kg were reported when DMBPC was tested at initial aqueous concentrations of 0.01 and 0.001 mg/L, respectively (Institute of Ecotoxicology, Ltd., 2003). These BCFs indicate that DMBPC has a low potential to bioaccumulate/ bioconcentrate. However, the original study report is in Japanese and only the abstract has been provided in English; therefore, a thorough assessment of study reliability could not be completed and the study was awarded a reliability score of 4 in accordance with the criteria set forth by Klimisch et al. (1997). An experimentally-determined log Kow of 3.1 (RCC Ltd., 2001g) supports the conclusion that DMBPC has low potential to bioaccumulate/bioconcentrate.

Taken together, these data support the argument that DMBPC is not bioaccumulative in aquatic/benthic species.

References:

Iizuka, N. 2003. Test on the degree of bioaccumulation of DMBPC in carp, Cyprinus carpio. Testing laboratory: Institute of Ecotoxicology, Ltd., Saitama City, Japan. Report no.: E4 -02030 -D28. Owner company: Anonymous. Report date: 2002 -10 -17.

Tognucci, A. 2001b. Determination of Partition Coefficient (n-Octanol/Water) of DMBPC. Testing laboratory: RCC Ltd., Itingen, Switzerland. Report no.: 798344. Owner company: Anonymous. Report date: 2001-07-05.