Registration Dossier

Ecotoxicological information

Sediment toxicity

Currently viewing:

Administrative data

Endpoint:
sediment toxicity
Type of information:
experimental study planned (based on read-across)
Study period:
maximum of 65 days
Justification for type of information:
Long-term toxicity to sediment organisms (Annex X, Section 9.5.1.; Test method: Sediment-water Chironomid toxicity using spiked sediment, OECD TG 218)

NON-CONFIDENTIAL NAME OF SUBSTANCE:
Name of the substance on which testing is proposed to be carried out: Cashew Nutshell Extract, Decarboxylated, Distilled (Distilled Grade) and Cashew Nutshell Extract, Decarboxylated, Distillation Residue (Distillation Residue Grade)
Name of the substance for which the testing proposal will be used [if different from tested substance]: Cashew Nutshell Extract, Decarboxylated (Technical Grade)
CONSIDERATIONS THAT THE GENERAL ADAPTATION POSSIBILITIES OF ANNEX XI OF THE REACH REGULATION ARE NOT ADEQUATE TO GENERATE THE NECESSARY INFORMATION [please address all points below]:
Available GLP and non-GLP studies
There is no existing reliable (GLP or non-GLP) data on the long-term toxicity of Cashew Nutshell Extract, Decarboxylated (Technical Grade) to sediment organisms. Technical grade has a log Kow = >6.2 with the logKow values for the different forms of cardanol and cardol predicted from the OECD QSAR Toolbox being from 8.37 to 8.96 and 7.89 to 8.46 respectively. Since the logkow values for the substance as a whole and for individual constituents exceed the threshold of log Kow = 3 it is considered to have the potential to sorb to particulate matter including bed sediments. It is also noted that the substance is not readily degradable, but may be ultimately biodegradable, in a robust OECD Guideline 310 Study [CO2 in sealed vessels (Headspace Test)] which showed a 69.3% loss based on CO2 production after 28 days. On this basis for any fraction either passing through the STP or potentially entering a surface water directly, will potentially not be degraded within a short period of time limiting losses of the sediment concentrations. The risk assessment suggests that there may be a remaining risk to sediment dwelling invertebrates. The information on this endpoint is not available for the registered substance, but needs to be present in the registration dossier to meet the information requirements.
Historical human data
Historical human data is not relevant to the assessment of the long-term toxicity to sediment organisms.
(Q)SAR
It has not been possible to provide reliable predictions of the long-term toxicity to sediment organisms exposed to Technical grade because appropriate models are not available in the OECD QSAR Toolbox.
In-vitro methods
The application of in vitro methods is not relevant to the assessment of the long-term toxicity to sediment organisms.
Grouping and read-across
It is not proposed that a test will be carried out on the registered Cashew Nutshell Extract, Decarboxylated, (Technical grade), but rather that appropriate tests will be carried out on two source substances Cashew Nutshell Extract, Decarboxylated, Distilled (Distilled grade) and Cashew Nutshell Extract, Decarboxylated, Distillation Residue (Distillation Residue grade) with the required data for Technical grade being interpolated by read-across. In this context interpolation is “the estimation of a value for a member of the group using measured values from other members on both sides of that member within the defined group spectrum”.
The justification for the read-across approach results from the commonality of the constituents and functional groups in the three grades and the common modes of action for specific localised endpoints that are manifest in physico-chemical, environmental fate and toxicological properties that are similar or follow a regular pattern as a result of structural similarity. Further details on the justification for using the interpolation based read-across approach are given in the accompanying document “Report on the development of an updated grouping and read-across rationale for the three grades of processed Cashew Nutshell extract”. The following points are relevant:
• The three grades are manufactured using a common process in which the unprocessed cashew nutshell extract is heated to produce Cashew Nutshell Extract, Decarboxylated (Technical grade), Subsequent distillation does not result in the formation of any new constituents in the resulting Distilled and Distillation Residue grades, but rather changes in the proportion of certain constituents relative to those present in Technical grade.

• In all the three grades the proportions of three out of the five key constituents namely the low boilers, C17 phenolics and high boilers (cardol and 2-methylcardol) are similar. Whilst the lightest, lower molecular weight non-polymeric constituents (such as cardanol) and the highest molecular weight polymeric constituents vary between grades Technical grade compositionally lies between Distilled and Distillation Residue grades.

• For all the physico-chemical parameters for which measured data are available the values estimated for the target substance Technical grade from the results generated in tests on the source substances Distilled and Distillation Residue grade are consistent with the actual measured values for Technical grade. The consistency of the estimated and measured values for these endpoints for Technical grade indicate that the read-across approach is appropriate and that reliable results can be generated by interpolation from the source substances (Distilled and Distillation Residue grades). In particular, there is consistency for the key physico-chemical parameters which are relevant to the long-term toxicity of the constituents of the three grades in sediment organisms namely: water solubility and octanol-water partition coefficient (logKow). The three grades show consistent octanol-water partition coefficients (logKow >6.2 in all cases) and low water solubilities (0.2 to 0.3 mg/l).

• The environmental fate properties of aerobic biodegradation and soil absorption (log Koc) for the three grades of processed cashew nutshell extract follow a regular pattern as a result of structural similarity, supporting the interpolation-based read-across approach. The observed log Koc values for Technical and Distilled Residue grade are the same (logKoc values of 4.4 -5.7). This endpoint has been waived for Distilled grade (as defined in Column 2 of Annex VIII of the REACH Regulation) because the substance decomposes rapidly as evidenced by the data from a Ready Biodegradability Study - Closed Bottle Test (OECD 301D). However, a logKoc value of 5.12 has been estimated from a logKow value of 6.2 using the Quantitative Structure Activity Relationship for calculating Koc from Kow for non-polar hydrophobic organics (log Koc =0.81 x logKow + 0.1) given in the Technical Guidance Document on Risk Assessment (EU, 1996).
As compositionally Technical grade lies between Distilled and Distillation Residue grades testing of the source substances will provide data on the degree to which the differences in the chemical composition (in terms of the lower molecular weight cardanols and higher molecular weight polymeric constituents) affect long-term toxicity to sediment organisms. The resulting read-across to Technical grade by interpolation is considered as an appropriate adaptation to the standard information requirements of Annex IX 9.5.1. of the REACH Regulation, in accordance with the provisions of Annex XI, 1.5 of the REACH Regulation. The use of data from two source substances (Distilled and Distilled Residue grades) to read-across to Technical grade is considered to provide greater confidence in the predicted data for the target substance.

CONSIDERATIONS THAT THE SPECIFIC ADAPTATION POSSIBILITIES OF ANNEXES VI TO X (AND COLUMN 2 THEREOF) OF THE REACH REGULATION ARE NOT ADEQUATE TO GENERATE THE NECESSARY INFORMATION:
Section 9.5.1 of Annex X of REACH states that “Long-term toxicity testing shall be proposed by the registrant if the results of the chemical safety assessment indicates the need to investigate further the effects of the substance and/or relevant degradation products on sediment organisms. The choice of the appropriate test(s) depends on the results of the chemical safety assessment”.
The current Risk Characterisation exercise for Technical grade within the Chemical Safety Report indicates that there is a potential risk to freshwater and marine sediments from certain exposure scenarios. However, the perceived risk may be a consequence of the rather precautionary PNECs for freshwater and marine water sediments which have been derived using the Equilibrium Partitioning approach in the absence of experimental data.
The data for Technical grade will be used to refine the PNECsediment, for freshwater and marine sediments which is consistent with the specific adaptation possibilities in Column 2 of Section 9.5.1 of REACH Annex X.
FURTHER INFORMATION ON TESTING PROPOSAL IN ADDITION TO INFORMATION PROVIDED IN THE MATERIALS AND METHODS SECTION:
It is proposed that the studies on the source substances Distilled and Distillation Residue grades will be carried out according to OECD Test Guideline 218 “Sediment-Water Chironomid Toxicity using Spiked Sediment” and to GLP. This study will assess the effects of prolonged exposure of Distilled and Distillation Residue grades to the sediment-dwelling larvae of the freshwater dipteran Chironomus sp. First instar chironomid larvae will be exposed to at least five concentrations of the test chemical in sediment-water systems. The test substances will be spiked into the sediment and first instar larvae will be subsequently introduced into test beakers in which the sediment and water concentrations have been stabilised. Chironomid emergence and development rate will be measured at the end of the test. The maximum exposure duration is 28 days for C. riparius, C. yoshimatsui, and 65 days for C. tentans. Larval survival and weight may also be measured after 10 days if required (using additional replicates as appropriate). The study report will include the development time and the total number of fully emerged midges (sex and number are recorded daily), the observation of any abnormal behaviour the number of visible pupae that have failed to emerge and any egg masses deposition. The testing will be supported by appropriate analytical confirmation of the exposure concentrations of key constituents such as cardanol and cardol.

Data source

Materials and methods

Test guideline
Qualifier:
according to
Guideline:
OECD Guideline 218 (Sediment-Water Chironomid Toxicity Test Using Spiked Sediment)

Test material

Reference
Name:
Unnamed
Type:
Constituent

Results and discussion

Applicant's summary and conclusion