Registration Dossier

Administrative data

Key value for chemical safety assessment

Effects on fertility

Description of key information
Gene expression associated with developmental toxicity: No repression of genes in the testicular mal-development pathway
Link to relevant study records
Reference
Endpoint:
reproductive toxicity, other
Type of information:
read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
key study
Justification for type of information:
REPORTING FORMAT FOR THE ANALOGUE APPROACH
A brief overview of the read-across study is reported below. Detailed information on the read-across justification is included in the read-across study report available in the "Attached justification" field. Please also refer to this report for the list of tools used in the assessment.

1. HYPOTHESIS FOR THE ANALOGUE APPROACH
The present read-across study falls within the RAAF scenario 2, i.e. analogue approach based on the hypothesis that different compounds are supposed to cause the same type of effects as a result of structural similarity.
In the current study, TM8, TOTM and TM8-10 were selected as source chemicals for the read-across prediction of reproductive and developmental toxicity for the UVCB target substance TM9. In particular, the sources TM8 and TOTM are mono-constituent substances, while the source TM8-10 and the target TM9 are UVCB substances. It is highlighted that the constituents of the target TM9, the sources TM8 and TOTM, and the constituents of the source TM8-10 belong to the same “pool” of structurally related constituents. Thus, according to the RAAF guidance for UVCB and MCSs5, structural similarity as a basis for the read-across may be assumed. Supporting information to further justify the analogue approach is provided by comparing the source and target substances in terms of mechanistic similarity, physico-chemical properties and ADME profile.

Additional details can be found in the attached read-across study report.

2. SOURCE AND TARGET CHEMICAL(S) (INCLUDING INFORMATION ON PURITY AND IMPURITIES)
Please refer to section 1.2 (general information/composition) of both target and source's IUCLID dossiers, and to the attached read-across study report.

3. ANALOGUE APPROACH JUSTIFICATION
Structural Similarity: Overall, the target TM9 exhibits high structural similarity toward the source substances TM8, TOTM and TM8-10. Minimal differences were identified among the analysed compounds due to the branching and lengths of the alkyl chains, however it is acknowledged that all of the functional groups and structural fragments of the target TM9 are represented by the source substances, which possess both linear and branched alkyl chains (as the target TM9) and cover almost the entire range of chain lengths from C8 to C10 (except for TM9 constituent 3, which possesses one C11 alkyl chain). It is then concluded that the target TM9 is included in the chemical space defined by the source compounds, thus reducing the uncertainty associated with structural similarity.

Concluding, the target and source substances exhibit high structural similarity. Uncertainty associated with structural similarity was assessed to be low.

Mechanistic similarity: The target and source compounds exhibited high mechanistic similarity. No structural alerts were identified in all target and source compounds by any of the profilers under consideration. This suggests that target and source compounds did not match the structural criteria specified in the boundaries of each profiling scheme. In particular, an unlikely binding to the estrogen-receptors (ER) interacting site was predicted for all chemicals, based on their high molecular weight (> 500 Da). Furthermore, no protein binding nor retinoic acid receptor binding alerts were found in all target and source compounds by the OECD QSAR Toolbox profilers. Additionally, no known precedent reproductive and developmental toxic potential was predicted by the DART scheme for target and source chemicals.
Finally, the OECD QSAR Toolbox HESS profiler for Repeated dose toxicity identified the phthalate ester alert in the target and the source compounds. It is further described in the profiler that it was found that toxicity induced by phthalate esters depends on their alkyl side-chain length. It was reported that phthalates with alkyl side-chain lengths from C4 to C6 produce similarly sever reproductive effects in experimental animals It is highlighted, that the profiler is characterised by a low rank of reliability (“Rank C” – i.e., toxicity mechanism not well known, category boundary experientially defined by using the repeated-dose toxicity (RDT) database test data).

Concluding, the target and source substances exhibited high mechanistic similarity. However, the uncertainty associated with mechanistic similarity was assessed as medium, due to limitations associated with the endpoint type.

Physico-chemical similarity:From the analysis and comparison of experimental and in silico predicted physico-chemical data, no major differences are noted between target and source substances. As expected from their chemical structure, which is characterised by rather long chains of carbon atoms, all of the analysed structures were both experimentally and predicted to be highly hydrophobic and insoluble, with LogKow values greater than 8 and water solubility (experimental and predicted) below 1 mg/L. Since no dissociating groups are found in both structures, pH has no influence on LogKow, water solubility, and ADME properties. Lastly, volatilisation is not expected to occur for all substances (boiling point greater than 150 °C, vapour pressure lower than < 500 Pa).
Concluding, the target and the source compounds exhibited high similarity in terms of their physico-chemical profile. Specifically, very high hydrophobicity, low water solubility, and no volatilisation potential were observed in target and source compounds. The uncertainty associated with PC similarity was assessed to be low.


ADME similarity: From the main results of the in-silico ADME analysis, a rather similar ADME profile was noted between the target TM9 and the sources TM8, TOTM, and TM10 (as for TM8-10).
Based on the predicted ADME data, target and source compounds exhibited a similar profile of highly lipophilic and poorly soluble substances, with a good passive absorption, a negligible oral bioavailability, a moderate first-pass metabolism, and high affinity to extravascular tissues. The experimental data available for the source TOTM showed that little of this substance was absorbed in a toxicokinetic study, since 75% of the initial dose was excreted in faeces, and 86% of which was TOTM unchanged. TOTM was found to be partially hydrolyzed in the gastro-intestinal tract to 2-ethylhexanol (2-EH) and the corresponding di-ester and, following further hydrolysis, the mono-ester. A low accumulation potential was also concluded for TOTM in the same study.
Based on the predicted physico-chemical and ADME properties, no major variations in the ADME profile of the target TM9 are expected due to interactions among target’s constituents.
Concluding, target and source compounds exhibited high similarity in terms of their predicted ADME profile. Overall, the uncertainty associated with ADME similarity was assessed to be low.



Potential metabolic products:Following the analysis of the simulated first level metabolites it is anticipated that all UVCB TM9 target’s constituents and source TM8, TOTM, TM10 (as for TM8-10) compounds have common biotransformation products resulting from Phase I metabolic reactions, including aromatic carboxylation and hydrolysis of the carboxylic acid esters. Predicted metabolites mainly include di-esters (benzene-1,2,4-tricarboxylic acid esterified by two alkyl chains (C8-C11)) and linear or branched alcohols (C8-C11) derived from the hydrolysis of one of the alkyl rich linear or branched substituents. In the 2nd level metabolism further hydrolysis and Phase II metabolism was predicted. With a very low odds ration primary alcohol oxidation was predicted resulting in e.g. a nonanol converted into nonanoic acid. Predicted metabolites were profiled also in terms of the OECD QSAR Toolbox and ACD/Percepta profilers relevant for reproductive and developmental toxicity. The profilers Estrogen receptor binding, rtER Expert System, Retinoid acid receptor binding, Development and Reproductive Toxicity (DART) scheme and Repeated dose HESS were applied. Based on these profilers, all compounds, target and source’s parent and metabolites are non estrogen receptor binder due to MW>500 and are non-classifiable according to rules for retinoic acid receptor binding. As for the DART scheme some metabolites from the target constituents and from the source TOTM were identified as “Beta alkyl substituted alcohols”, which are known to have precedent reproductive and developmental toxic potential. Metabolites from all parent compounds (target and sources) resulting from hydroxylation, were assigned to the group of salicylates. Finally, based on the HESS profiler forRepeated Dose toxicity, all hydroxylated and diester metabolites from the target constituents and the source compounds were identified as phthalate esters relating to testicular toxicity (Rank C).

Concluding, the target and source substances exhibited high similarity in terms of their potential metabolites. In particular, the fact that all substances are likely to undergo to ester hydrolysis find confirmation in experimental toxicokinetic studies. The predicted metabolites showed high structural and mechanistic similarity. Thus, the uncertainty associated with the identification of potential metabolic products was assessed to be low.


Source experimental data: Reporductive and developmental toxicity data were available for the source compounds TM8, TOTM and TM8-10. Study reports were reported to be reliable without or with restrictions (Klimisch score 1 or 2), most of them being GLP-compliant. Some repeated Dose Oral Toxicity in Rodents were considered as supporting studies, as they included aspects relevant for reproductive toxicity evaluation.

4. DATA MATRIX
In the read-across analysis, TM8, TOTM and TM8-10 was selected as source chemical for the target TM9. The similarity assessment, which consisted of a comparison of structural, mechanistic, physicochemical, ADME and metabolism profiles, showed that the sources TM8, TOTM and TM8-10 and the target TM9 are sufficiently similar to justify the read-across approach.
The data matrix is included in the attached report.
Reason / purpose:
read-across source
Remarks:
TM8 Screening study
Reason / purpose:
read-across source
Remarks:
TOTM Screening study
Reason / purpose:
read-across source
Remarks:
TM8 90 day Repeated dose
Reason / purpose:
read-across source
Remarks:
TOTM 90 day repeated dose
Reason / purpose:
read-across source
Remarks:
TM8 developmental toxicity
Reason / purpose:
read-across source
Remarks:
TOTM developmental toxicity
Reason / purpose:
read-across source
Remarks:
TM8-10 developmental toxicity
Qualifier:
according to
Guideline:
other: ECHA, 2015: Read-Across Assessment Framework (RAAF).
Qualifier:
according to
Guideline:
other: ECHA, 2017: Read-Across Assessment Framework (RAAF). Considerations on multi-constituent substances and UVCBs.
Specific details on test material used for the study:
EC: 941-303-6
Type: UVCB substance
Key result
Dose descriptor:
NOEL
Effect level:
500 mg/kg bw/day (nominal)
Based on:
other: Source TM8
Sex:
male/female
Basis for effect level:
other: Absence of effects on reproductive performance or sex organs
Remarks on result:
other:
Remarks:
Read-across
Key result
Dose descriptor:
NOEL
Effect level:
100 mg/kg bw/day (nominal)
Based on:
other:
Remarks:
Source TOTM
Sex:
male
Basis for effect level:
other: Histopathology; sperm characterization, numbers & ratio of sertoli cells in males given 1000 mg/kg/day TOTM & reduced numbers of spermatids in animals given 300 mg/kg/day
Remarks on result:
other:
Remarks:
Read-across
Key result
Dose descriptor:
NOEL
Effect level:
1 000 mg/kg bw/day (nominal)
Based on:
other: Source TOTM
Sex:
female
Basis for effect level:
other: see "Remark"
Remarks on result:
other:
Remarks:
Read-across
Key result
Dose descriptor:
NOAEL
Generation:
F1
Effect level:
500 mg/kg bw/day (nominal)
Based on:
other: Source TM8
Sex:
male/female
Basis for effect level:
other: Absence of effects on pup weight; sex ratio; survival index; viability index
Key result
Dose descriptor:
NOEL
Generation:
F1
Effect level:
1 000 mg/kg bw/day (nominal)
Based on:
other: Source TOTM
Sex:
male/female
Basis for effect level:
viability
Critical effects observed:
no
Reproductive effects observed:
not specified
Conclusions:
Reproductive and developmental toxicity experimental studies in rodents were available for the source TM8, TOTM and TM8-10. The studies were assessed as adequate for the read-across prediction for the target TM9. Based on the read-across study presented, it is concluded that the reproductive and developmental toxicity data available for the source TM8, TOTM and TM8-10 could be used to support the assessment of TM9.
Executive summary:

This study was designed to generate read-across predictions ofreproductive and developmental toxicityfor the UVCB TM9. The target TM9 is an esterification products of 1,3-dioxo-2-benzofuran-5-carboxylic acid and nonan-1-ol, C9 linear alkyl rich and is to be used for its safety assessment in the regulatory framework of REACH.

The target is composed by nine main constituents (one mono-constituent and eight UVCB substances for about 50 structures), which share a common core structure, i.e. benzene-1,2,4-tricarboxylic acid, esterified by linear and/or branched C8-C11 alkyl chains (C9 rich). In the present assessment, 15 of these substances were selected as representative compounds of the target TM9.

In theread-across analysis,three sources of experimental data were selected, the mono-constituents TM8 and TOTM, and the UVCB TM8-10. The target and source substances belong to the same “pool” of structurally related constituents, since they share a common core structure, i.e. benzene-1,2,4-tricarboxylic acid, esterified by linear and/or branched C8-C11 alkyl chains. Thus, according to the RAAF guidance for UVCBs, structural similarity as a basis for the read-across may be assumed.The similarity assessment, which consisted of a comparison of structural, mechanistic, physicochemical, ADME and metabolism profiles, showedthat the three sourcesand the targetTM9are sufficiently similar to justify the read-across approach. Experimental reproductive and developmental toxicity studies were available for three sources. Additionally, 90-day repeated dose toxicity studies for TM8 and TM8-10 assessing some reproductive parameters, were available as supporting studies.

QSAR predictions for endpoints relevant for reproductive and developmental toxicity were performed for the target substance TM9 (considering the 15 representative compounds). Both positive and negative predictions were generated, according to the different endpoints and species; most of the predictions were assessed as borderline reliable. These QSAR predictions were not used to further support the read-across prediction for reproductive and developmental toxicity since assessed of limited relevance, thus are not contributing to reduce the read-across uncertainty.

In the present read-across study, an overall low uncertainty was associated with similarity justification. However, the following issues are highlighted: i) the endpoint to read-across does not have yet well-defined mechanistic bases (high-tier endpoint, ii) ADME assessment was mainly based on simulated data; iii) identification of potential metabolites and related structural and mechanistic profiles was mainly based onin silicopredictions. The main uncertainties associated with the read-across argument were related to the following issues: i) endpoint-type, ii) no bridging studies among the source and target substances.

Concluding, the read-across from the reproductive and developmental toxicityexperimental studies in rats, which areavailable forthe source substances TM8 and TOTM and TM8-10, are likely to predict the reproductive and developmental toxicity potential of the target substance TM9 and are considered as adequate to fulfil the information requirement of Annex VIII 8.7 of the REACH Regulation.

Effect on fertility: via oral route
Endpoint conclusion:
no adverse effect observed
Dose descriptor:
NOAEL
500 mg/kg bw/day
Study duration:
subacute
Species:
rat
Effect on fertility: via inhalation route
Endpoint conclusion:
no study available
Effect on fertility: via dermal route
Endpoint conclusion:
no study available
Additional information

In a repeat-dose toxicity combined with a screening study of reproductive toxicity on a structurally similar trimellitate, the linear alcohol ester side chains of the molecule being C8 rather than C9 of the registered substance, no significant effect on reproductive ability, organ weight or histopathology of the ovary, delivery or maternal behaviour was apparent. The NOEL for reproductive / developmental toxicity was considered to be 500 mg/kg/day for both parents and offspring, the highest dose examined. An OECD screening study of reproductive toxicity on another trimellitate, this with C8 branched alcohol ester side chains, revealed no functional changes in fertility or reproductive performance although histopathological examination revealed reduced spermatocytes & spermatids in the testes of males given the substance at doses of 300 and 1000 mg/kg/day. The NOELs for systemic toxicity were considered to be 100 & 1000 mg/kg/day for males & females respectively. The NOEL for reproductive / developmental toxicity is considered to be 1000 mg/kg/day for offspring.It is noted that, in a repeat dose toxicity study of 90 -days duration, approximately double that of the screening study, the testicular effects described above were not seen.

An extended one generation reproductive toxicity study is required in accordance with Section 8.7.3 of Column 1, Annex IX. It is proposed to waive the need to conduct this study on the basis of the fact that well-conducted OECD 421 reproductive/developmental toxicity screening studies and data from subchronic repeat dose toxicity studies show no functional effect on the reproductive performance of both male and female rats. These studies provide adequate data to demonstrate the potential toxicity to reproduction of the substance to humans and to derive relevant DNELs for oral exposure. Furthermore, it is well known that, for this class of substance, the principle reproductive toxicity potential is towards the developing male testes. This aspect of the toxicological profile has been studied adequately using RNA transcriptional profiling in an assay that subscribes to the principle of the 3R’s.


Short description of key information:
Reproductive toxicity - Rat: NO(A)EL - 500 mg/kg/day

Justification for selection of Effect on fertility via oral route:
Studies are available on two structural analogues of the registered substance, the selected study being that on the closest structural analogue to the registered substance.

Effects on developmental toxicity

Description of key information
Developmental toxicity - Rat: NO(A)EL 1000 mg/kg/day
Link to relevant study records
Reference
Endpoint:
developmental toxicity
Type of information:
read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
key study
Justification for type of information:
REPORTING FORMAT FOR THE ANALOGUE APPROACH
A brief overview of the read-across study is reported below. Detailed information on the read-across justification is included in the read-across study report available in the "Attached justification" field. Please also refer to this report for the list of tools used in the assessment.

1. HYPOTHESIS FOR THE ANALOGUE APPROACH
The present read-across study falls within the RAAF scenario 2, i.e. analogue approach based on the hypothesis that different compounds are supposed to cause the same type of effects as a result of structural similarity.
In the current study, TM8, TOTM and TM8-10 were selected as source chemicals for the read-across prediction of reproductive and developmental toxicity for the UVCB target substance TM9. In particular, the sources TM8 and TOTM are mono-constituent substances, while the source TM8-10 and the target TM9 are UVCB substances. It is highlighted that the constituents of the target TM9, the sources TM8 and TOTM, and the constituents of the source TM8-10 belong to the same “pool” of structurally related constituents. Thus, according to the RAAF guidance for UVCB and MCSs5, structural similarity as a basis for the read-across may be assumed. Supporting information to further justify the analogue approach is provided by comparing the source and target substances in terms of mechanistic similarity, physico-chemical properties and ADME profile.

Additional details can be found in the attached read-across study report.

2. SOURCE AND TARGET CHEMICAL(S) (INCLUDING INFORMATION ON PURITY AND IMPURITIES)
Please refer to section 1.2 (general information/composition) of both target and source's IUCLID dossiers, and to the attached read-across study report.

3. ANALOGUE APPROACH JUSTIFICATION
Structural Similarity: Overall, the target TM9 exhibits high structural similarity toward the source substances TM8, TOTM and TM8-10. Minimal differences were identified among the analysed compounds due to the branching and lengths of the alkyl chains, however it is acknowledged that all of the functional groups and structural fragments of the target TM9 are represented by the source substances, which possess both linear and branched alkyl chains (as the target TM9) and cover almost the entire range of chain lengths from C8 to C10 (except for TM9 constituent 3, which possesses one C11 alkyl chain). It is then concluded that the target TM9 is included in the chemical space defined by the source compounds, thus reducing the uncertainty associated with structural similarity.

Concluding, the target and source substances exhibit high structural similarity. Uncertainty associated with structural similarity was assessed to be low.

Mechanistic similarity: The target and source compounds exhibited high mechanistic similarity. No structural alerts were identified in all target and source compounds by any of the profilers under consideration. This suggests that target and source compounds did not match the structural criteria specified in the boundaries of each profiling scheme. In particular, an unlikely binding to the estrogen-receptors (ER) interacting site was predicted for all chemicals, based on their high molecular weight (> 500 Da). Furthermore, no protein binding nor retinoic acid receptor binding alerts were found in all target and source compounds by the OECD QSAR Toolbox profilers. Additionally, no known precedent reproductive and developmental toxic potential was predicted by the DART scheme for target and source chemicals.
Finally, the OECD QSAR Toolbox HESS profiler for Repeated dose toxicity identified the phthalate ester alert in the target and the source compounds. It is further described in the profiler that it was found that toxicity induced by phthalate esters depends on their alkyl side-chain length. It was reported that phthalates with alkyl side-chain lengths from C4 to C6 produce similarly sever reproductive effects in experimental animals It is highlighted, that the profiler is characterised by a low rank of reliability (“Rank C” – i.e., toxicity mechanism not well known, category boundary experientially defined by using the repeated-dose toxicity (RDT) database test data).

Concluding, the target and source substances exhibited high mechanistic similarity. However, the uncertainty associated with mechanistic similarity was assessed as medium, due to limitations associated with the endpoint type.

Physico-chemical similarity:From the analysis and comparison of experimental and in silico predicted physico-chemical data, no major differences are noted between target and source substances. As expected from their chemical structure, which is characterised by rather long chains of carbon atoms, all of the analysed structures were both experimentally and predicted to be highly hydrophobic and insoluble, with LogKow values greater than 8 and water solubility (experimental and predicted) below 1 mg/L. Since no dissociating groups are found in both structures, pH has no influence on LogKow, water solubility, and ADME properties. Lastly, volatilisation is not expected to occur for all substances (boiling point greater than 150 °C, vapour pressure lower than < 500 Pa).
Concluding, the target and the source compounds exhibited high similarity in terms of their physico-chemical profile. Specifically, very high hydrophobicity, low water solubility, and no volatilisation potential were observed in target and source compounds. The uncertainty associated with PC similarity was assessed to be low.


ADME similarity: From the main results of the in-silico ADME analysis, a rather similar ADME profile was noted between the target TM9 and the sources TM8, TOTM, and TM10 (as for TM8-10).
Based on the predicted ADME data, target and source compounds exhibited a similar profile of highly lipophilic and poorly soluble substances, with a good passive absorption, a negligible oral bioavailability, a moderate first-pass metabolism, and high affinity to extravascular tissues. The experimental data available for the source TOTM showed that little of this substance was absorbed in a toxicokinetic study, since 75% of the initial dose was excreted in faeces, and 86% of which was TOTM unchanged. TOTM was found to be partially hydrolyzed in the gastro-intestinal tract to 2-ethylhexanol (2-EH) and the corresponding di-ester and, following further hydrolysis, the mono-ester. A low accumulation potential was also concluded for TOTM in the same study.
Based on the predicted physico-chemical and ADME properties, no major variations in the ADME profile of the target TM9 are expected due to interactions among target’s constituents.
Concluding, target and source compounds exhibited high similarity in terms of their predicted ADME profile. Overall, the uncertainty associated with ADME similarity was assessed to be low.



Potential metabolic products:Following the analysis of the simulated first level metabolites it is anticipated that all UVCB TM9 target’s constituents and source TM8, TOTM, TM10 (as for TM8-10) compounds have common biotransformation products resulting from Phase I metabolic reactions, including aromatic carboxylation and hydrolysis of the carboxylic acid esters. Predicted metabolites mainly include di-esters (benzene-1,2,4-tricarboxylic acid esterified by two alkyl chains (C8-C11)) and linear or branched alcohols (C8-C11) derived from the hydrolysis of one of the alkyl rich linear or branched substituents. In the 2nd level metabolism further hydrolysis and Phase II metabolism was predicted. With a very low odds ration primary alcohol oxidation was predicted resulting in e.g. a nonanol converted into nonanoic acid. Predicted metabolites were profiled also in terms of the OECD QSAR Toolbox and ACD/Percepta profilers relevant for reproductive and developmental toxicity. The profilers Estrogen receptor binding, rtER Expert System, Retinoid acid receptor binding, Development and Reproductive Toxicity (DART) scheme and Repeated dose HESS were applied. Based on these profilers, all compounds, target and source’s parent and metabolites are non estrogen receptor binder due to MW>500 and are non-classifiable according to rules for retinoic acid receptor binding. As for the DART scheme some metabolites from the target constituents and from the source TOTM were identified as “Beta alkyl substituted alcohols”, which are known to have precedent reproductive and developmental toxic potential. Metabolites from all parent compounds (target and sources) resulting from hydroxylation, were assigned to the group of salicylates. Finally, based on the HESS profiler forRepeated Dose toxicity, all hydroxylated and diester metabolites from the target constituents and the source compounds were identified as phthalate esters relating to testicular toxicity (Rank C).

Concluding, the target and source substances exhibited high similarity in terms of their potential metabolites. In particular, the fact that all substances are likely to undergo to ester hydrolysis find confirmation in experimental toxicokinetic studies. The predicted metabolites showed high structural and mechanistic similarity. Thus, the uncertainty associated with the identification of potential metabolic products was assessed to be low.


Source experimental data: Reporductive and developmental toxicity data were available for the source compounds TM8, TOTM and TM8-10. Study reports were reported to be reliable without or with restrictions (Klimisch score 1 or 2), most of them being GLP-compliant. Some repeated Dose Oral Toxicity in Rodents were considered as supporting studies, as they included aspects relevant for reproductive toxicity evaluation.

4. DATA MATRIX
In the read-across analysis, TM8, TOTM and TM8-10 was selected as source chemical for the target TM9. The similarity assessment, which consisted of a comparison of structural, mechanistic, physicochemical, ADME and metabolism profiles, showed that the sources TM8, TOTM and TM8-10 and the target TM9 are sufficiently similar to justify the read-across approach.
The data matrix is included in the attached report.
Reason / purpose:
read-across source
Remarks:
TM8
Reason / purpose:
read-across source
Remarks:
TOTM
Reason / purpose:
read-across source
Remarks:
TM8-10
Reason / purpose:
read-across source
Remarks:
TM8
Qualifier:
according to
Guideline:
other: ECHA, 2017: Read-Across Assessment Framework (RAAF). Considerations on multi-constituent substances and UVCBs.
Qualifier:
according to
Guideline:
other: ECHA, 2015: Read-Across Assessment Framework (RAAF).
Specific details on test material used for the study:
EC: 941-303-6
TYPE: UVCB
Key result
Dose descriptor:
LOAEL
Effect level:
1 000 mg/kg bw/day (nominal)
Based on:
other: Source TM8
Basis for effect level:
body weight and weight gain
food consumption and compound intake
Remarks on result:
other:
Remarks:
Read-across
Key result
Dose descriptor:
NOAEL
Effect level:
1 050 mg/kg bw/day (nominal)
Based on:
other: Source TOTM
Basis for effect level:
other: overall effects
Remarks on result:
other:
Remarks:
Read-across
Key result
Dose descriptor:
LOAEL
Effect level:
1 000 mg/kg bw/day (actual dose received)
Based on:
other: Source TM8-10
Basis for effect level:
body weight and weight gain
food consumption and compound intake
gross pathology
Remarks on result:
other:
Remarks:
Read-across
Key result
Dose descriptor:
NOAEL
Effect level:
1 000 mg/kg bw/day (nominal)
Based on:
other: Source TM8
Sex:
not specified
Basis for effect level:
other: Lack of treatment related effects
Remarks on result:
other:
Remarks:
Read-across
Key result
Dose descriptor:
NOAEL
Effect level:
1 050 mg/kg bw/day (nominal)
Based on:
other: Source TOTM
Remarks:
pre-natal developmental
Sex:
male/female
Basis for effect level:
reduction in number of live offspring
changes in sex ratio
fetal/pup body weight changes
changes in litter size and weights
changes in postnatal survival
external malformations
skeletal malformations
visceral malformations
other: Lack of significant effects in above parameters
Remarks on result:
other:
Remarks:
Read-across
Key result
Dose descriptor:
NOAEL
Effect level:
500 mg/kg bw/day (nominal)
Based on:
other: Source TOTM
Remarks:
postnatal
Sex:
male
Basis for effect level:
other: Retained areolar region PND 13, no longer present PND 18
Remarks on result:
other: Read-across
Key result
Dose descriptor:
NOAEL
Effect level:
1 000 mg/kg bw/day (actual dose received)
Based on:
other: Source TM8-10
Sex:
male/female
Basis for effect level:
other: Lack of significant effects on developmental toxicity
Remarks on result:
other: Read-across
Abnormalities:
no effects observed
Developmental effects observed:
no
Conclusions:
Reproductive and developmental toxicity experimental studies in rodents were available for the source TM8, TOTM and TM8-10. The studies were assessed as adequate for the read-across prediction for the target TM9. Based on the read-across study presented, it is concluded that the reproductive and developmental toxicity data available for the source TM8, TOTM and TM8-10 could be used to support the assessment of TM9.
Executive summary:

This study was designed to generate read-across predictions ofreproductive and developmental toxicityfor the UVCB TM9. The target TM9 is an esterification products of 1,3-dioxo-2-benzofuran-5-carboxylic acid and nonan-1-ol, C9 linear alkyl rich and is to be used for its safety assessment in the regulatory framework of REACH.

The target is composed by nine main constituents (one mono-constituent and eight UVCB substances for about 50 structures), which share a common core structure, i.e. benzene-1,2,4-tricarboxylic acid, esterified by linear and/or branched C8-C11 alkyl chains (C9 rich). In the present assessment, 15 of these substances were selected as representative compounds of the target TM9.

In theread-across analysis,three sources of experimental data were selected, the mono-constituents TM8 and TOTM, and the UVCB TM8-10. The target and source substances belong to the same “pool” of structurally related constituents, since they share a common core structure, i.e. benzene-1,2,4-tricarboxylic acid, esterified by linear and/or branched C8-C11 alkyl chains. Thus, according to the RAAF guidance for UVCBs, structural similarity as a basis for the read-across may be assumed.The similarity assessment, which consisted of a comparison of structural, mechanistic, physicochemical, ADME and metabolism profiles, showedthat the three sourcesand the targetTM9are sufficiently similar to justify the read-across approach. Experimental reproductive and developmental toxicity studies were available for three sources. Additionally, 90-day repeated dose toxicity studies for TM8 and TM8-10 assessing some reproductive parameters, were available as supporting studies.

QSAR predictions for endpoints relevant for reproductive and developmental toxicity were performed for the target substance TM9 (considering the 15 representative compounds). Both positive and negative predictions were generated, according to the different endpoints and species; most of the predictions were assessed as borderline reliable. These QSAR predictions were not used to further support the read-across prediction for reproductive and developmental toxicity since assessed of limited relevance, thus are not contributing to reduce the read-across uncertainty.

In the present read-across study, an overall low uncertainty was associated with similarity justification. However, the following issues are highlighted: i) the endpoint to read-across does not have yet well-defined mechanistic bases (high-tier endpoint, ii) ADME assessment was mainly based on simulated data; iii) identification of potential metabolites and related structural and mechanistic profiles was mainly based onin silicopredictions. The main uncertainties associated with the read-across argument were related to the following issues: i) endpoint-type, ii) no bridging studies among the source and target substances.

Concluding, the read-across from the reproductive and developmental toxicityexperimental studies in rats, which areavailable forthe source substances TM8 and TOTM and TM8-10, are likely to predict the reproductive and developmental toxicity potential of the target substance TM9 and are considered as adequate to fulfil the information requirement of Annex VIII 8.7 of the REACH Regulation.

Effect on developmental toxicity: via oral route
Endpoint conclusion:
no adverse effect observed
Dose descriptor:
LOAEL
1 000 mg/kg bw/day
Effect on developmental toxicity: via inhalation route
Endpoint conclusion:
no study available
Effect on developmental toxicity: via dermal route
Endpoint conclusion:
no study available
Additional information

A developmental toxicity study in the rat, extended to permit an assessment of post-natal development, conducted on a structurally similar trimellitate, the linear alcohol ester side chains of the molecule being C8 to C10 rather than C9 of the registered substance, found no exposure related developmental toxic effects, findings being limited to indicators of maternal toxicity.On the basis of the results obtained, 300 mg/kg/day was considered the NOAEL for maternal toxicity and 1000 mg/kg/day the NOAEL for embryo-foetal effects.

In a study on another trimellitate, this with C8 branched alcohol ester side chains, no treatment-related effects indicative of maternal toxicity and no effects on offspring body weights or litter viability were observed. No developmental (teratogenic) effects were observed and there were no effects upon sexual maturation or development of the reproductive tract in male or female offspring that were attributed to treatment. No effects levels were:

NOEL maternal toxicity: 1050 mg/kg/day

NOEL pre-natal developmental toxicity: 1050 mg/kg/day

NOEL post-natal evaluation of offspring: 500 mg/kg/day; LOAEL: 1050 mg/kg/day (slight increase in retained areolar region in males treated at 1050 mg/kg/day post-natal Day 13, no longer present post-natal day 18 and slightly higher increase in displaced testes compared to controls although the observed incidence was within the range of historical control data).

It is considered that for this class of substance, by association with phthalate esters, the principle concern regarding developmental toxicity is towards the developing male testes. This aspect of the toxicological profile has been studied in detail using RNA transcriptional profiling in an assay that subscribes to the principle of the 3R’s.


Justification for selection of Effect on developmental toxicity: via oral route:
Studies are available on two structural analogues of the registered substance, the selected study being that on the closest structural analogue to the registered substance.

Toxicity to reproduction: other studies

Additional information

Studies on structurally similar trimellitates, one with the linear alcohol ester side chains of the molecule being C8 to C10 rather than C9 of the registered substance and another with C8 branched alcohol ester side chains, examined the effects on gene expression associated with developmental toxicity in male rat foetal testes by transcriptional profiling. The outcome of these studies indicate that the substances do not cause repression of genes in the testicular mal-development pathway indicating that they are unlikely to cause testicular dysgenesis in rats as is seen with some phthalate esters.

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Justification for classification or non-classification

Studies of reproductive have revealed no functional changes in fertility or reproductive performance other than, in a screening study of reproductive toxicity, reduced spermatocytes & spermatids in the testes of males given a trimellitate with C8 branched alcohol ester side chains at doses of 300 or 1000 mg/kg/day. Such effects were not apparent with this substance at dose levels as high as 1000 mg/kg/day in a sub-chronic study of 90 days duration, the duration of exposure being approximately double that of the screening study. Studies of effects on gene expression associated with developmental toxicity in male rat foetal testes by transcriptional profiling indicate that the substances do not cause repression of genes in the testicular mal-development pathway, indicating that the substances are unlikely to cause testicular dysgenesis in rats. A pre- and post-natal developmental toxicity study with a trimellitate containing C8 branched alcohol ester side chains revealed no effects on developmental toxicity at a dose level of 500 mg/kg/day. At the higher dose level of 1050 mg/kg/day a slight increase in retained areolar region was observed in males on post-natal Day 13 which was no longer present post-natal day 18. A slightly higher increase in displaced testes compared to controls was also seen although the observed incidence was within the range of historical control data. A similar study with a trimellitate containing linear alcohol ester side chains of C8 to C10 length (rather than C9 of the registered substance), found no exposure related developmental toxic effects, findings being limited to indicators of maternal toxicity. In this study the NOAEL for embryo-foetal effects was regarded as being 1000 mg/kg/day.

In accordance with Regulation (EC) No. 1272/2008 effects such as small changes in semen parameters or in the incidence of spontaneous defects in the foetus, small changes in the proportions of common foetal variants such as are observed in skeletal examinations, or in foetal weights, or small differences in postnatal developmental assessments are considered to be of low or minimal toxicological significance insufficient to warrant classification.