Registration Dossier

Administrative data

Endpoint:
extended one-generation reproductive toxicity - basic test design (Cohorts 1A, and 1B without extension)
Type of information:
experimental study planned
Justification for type of information:
Testing Proposal_OECD 443

TESTING PROPOSAL ON VERTEBRATE ANIMALS
[Please provide information for all of the points below. The information should be specific to the endpoint for which testing is proposed. Note that for testing proposals addressing testing on vertebrate animals under the REACH Regulation this document will be published on the ECHA website along with the third party consultation on the testing proposal(s).]

NON-CONFIDENTIAL NAME OF SUBSTANCE:
- Name of the substance on which testing is proposed to be carried out: N,N'-dimethylbenzylamin (CAS 103-83-3)

- Name of the substance for which the testing proposal will be used [if different from tested substance]: not applicable

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 studies: There are 2 sub-acute oral studies available which are performed according the respective guideline and in which the test substance was applied by gavage to male and female rats in dosages of 0, 6, 30, 150, 200 mg/kg bw/day (BG Chemie 1988, 1990) or 0, 50, 100, 200, 400 mg/kg bw/day (MHLW 1997), respectively. In addition, rats of the control group and rats treated with 200 and 400 mg/kg bw/day were observed after termination of treatment for further 2 weeks (recovery group, MHLW 1997).
Mortalities of both males and females receiving 400 mg/kg were observed from week 2. Miosis and salivation was observed in those rats receiving 200 and 400 mg/kg bw/day. The 150 mg/kg bw/day males had slightly higher testis weights than the controls. However, there was no histopathological correlate. In male and female animals dosed with 100 mg/kg bw/day miosis was the only observed finding. There were no differences between controls and male and female rats dosed with 50, 30 or 6 mg/kg bw/day. Thus, the overall NOAEL is considered to be 150 mg/kg bw/day.
In an OECD TG 414 study pregnant female rats received orally 0, 35, 75 and 150 mg/kg bw/day by gavage on gestation day 5 -19. All females were terminated on gestation day 20 and cesarian section was performed to evaluate the developing organism.
At the highest dose of 150 mg/kg bw/day females gained markedly less body weight (by 41 % compared to control) and a reduction (-13 %) in overall food consumption. Fertility index and gestation index was calculated to be 100 % in all treated animals including control animals. Post mortem, no macroscopic abnormalities were observed. Thus, due to the reduced weight gain at 150 mg/kg bw/day the NOAEL (maternal toxicity) is considered 75 mg/kg bw/day.
No treatment related effects were detected in foetal viability (male and female), or in foetal weights (male and females), or in growth and development. Sex ratio was in the normal range. No treatment related effects were detected on fetal external findings.
No treatment-related effects were detected on skeletal development (including osseous and cartilaginous tissue) and none in the type and incidence of skeletal or visceral findings in fetuses from females treated with 150, 75 or 35 mg/kg bw/day.
A teratogenic effect of treatment was not evident up to and including the highest dose level (150 mg/kg bw/day).
Thus, the NOEL (No Adverse Effect Level) for reproductive and developmental toxicity is considered to be 150 mg/kg bw/day.
In conclusion, despite general toxicity (body weight reduction) in female rats at 150 mg/kg bw/day there is no evidence that the substance shows developmental toxicity.

- Available non-GLP studies: (no data available).

- Historical human data: (no data available).

- (Q)SAR: (no reliable data available; there is no QSAR model available which is accepted by ECHA for the endpoint developmental toxicity). According to DART profiler of the QSAR Toolbox 4.3.1. N,N-dimethylbenzylamine is not a developmental or reproductive toxicant. Additional information of the outcome of the QSAR Toolbox 4.3.1 see ‘Grouping and read-across´.

- In vitro methods: (no reliable data available; there are no in vitro methods available which are accepted by ECHA for the endpoint developmental toxicity).

- Weight of evidence: (no data available; in an test according to OECD TG 407 and GLP groups of male and female Crl:CD(SD)BR rats received N,N-dimethylbenzylamine in corn oil by daily oral gavage at nominal dose levels of 6, 30 or 150 mg/kg bw/day. A further group of the same size received corn oil alone and served as control.
There were no effects observed in female reproductive organs. In males at the highest dose groups the mean absolute and relative testis weight was slightly increased when compared to the respective control. However, there was no histopathological correlate and therefore these effects were not considered to be of toxicological relevance. Thus, the NOAEL (reproductive organs) was determined to be 150 mg/kg bw/day for male and female rats (BG Chemie 1988).
N,N-dimethylbezylamine was given by gavage to male and female Crj:CD (SD) rats in doses of 0 (corn oil), 40, 100, 200, 400 mg/kg bw/day diluted in corn oil over a period of 28 days. In addition, animals of the control group and animals treated with 200 and 400 mg/kg bw/day were observed after termination of treatment for further 2 weeks (recovery group). No effects on reproductive organs were observed up to the highest test dose. Thus, the NOAEL (reproductive organs is determined to be 400 mg/kg bw/day (MHLW 1997).
The available data of 2 sub-acute studies are not sufficient to replace an EOGRTS study according to OECD TG 443.
A weight of evidence consideration is therefore not feasible.

- Grouping and read-across: The QSAR Toolbox 4.3.1 has proposed 17 compounds (Empiric: Organic functional groups after sub-categorisation) for a read-across. Two of them seems suitable for a read-across due to their near structural similarity to the target compound.
The compounds are CAS no. 4788-37-8 (N-Ethyl-N-methylbenzylamine) and CAS no. 772-54-3 (N,N-diethylbenzylamine).
CAS no. 4788-37-8 has a methy and an ethyl substituent instead of methyl substituents at the N-atom.
CAS no. 772-54-3 has ethyl substituents instead of methyl substituents at the N-atom.
For both substances no toxicological data for repeated dose toxicity and developmental toxicity were found. Therefore, a read-across is based on the absence of toxicological data for these endpoints not possible.
The other compounds proposed by the QSAR Toolbox 4.3.1 are structurally more different to the target compound. Additionally, no toxicological data for these compounds are available in the QSAR Toolbox 4.3.1.

- Substance-tailored exposure driven testing [if applicable]: not applicable.

- Approaches in addition to above [if applicable]: not applicable.

- Other reasons [if applicable]: not applicable.

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:
There is no EOGRTS study available.

According to COMMISSION REGULATION (EU) 2015/282 of 20 February 2015 amending Annexes VIII, IX and X to Regulation (EC) No 1907/2006 of the European Parliament and of the Council on the Registration, Evaluation, Authorisation and Restriction of Chemicals (REACH) as regards the Extended One-Generation Reproductive Toxicity Study in Annex 8.7.3 an Extended One-Generation Reproductive Toxicity Study (B.56 of the Commission Regulation on test methods as specified in Article 13(3) or OECD 443), basic test design (cohorts 1A and 1B without extension to include a F2 generation), one species, most appropriate route of administration, having regard to the likely route of human exposure is a standard information requirement.
An Extended One-Generation Reproductive Toxicity Study with the extension of cohort 1B to include the F2 generation shall be proposed by the registrant or may be required by the Agency in accordance with Article 40 or 41, if:
(a) the substance has uses leading to significant exposure of consumers or professionals, taking into account, inter alia, consumer exposure from articles, and
(b) any of the following conditions are met:
— the substance displays genotoxic effects in somatic cell mutagenicity tests in vivo which could lead to classifying it as Mutagen Category 2, or
— there are indications that the internal dose for the substance and/or any of its metabolites will reach a steady state in the test animals only after an extended exposure, or
— there are indications of one or more relevant modes of action related to endocrine disruption from available in vivo studies or non-animal approaches.

An Extended One-Generation Reproductive Toxicity Study including cohorts 2A/2B (developmental neurotoxicity) and/or cohort 3 (developmental immunotoxicity) shall be proposed by the registrant or may be required by the Agency in accordance with Article 40 or 41, in case of particular concerns on (developmental) neurotoxicity or (developmental) immunotoxicity justified by any of the following:
— existing information on the substance itself derived from relevant available in vivo or non-animal approaches (e.g. abnormalities of the CNS, evidence of adverse effects on the nervous or immune system in studies on adult animals or animals exposed prenatally), or
— specific mechanisms/modes of action of the substance with an association to (developmental) neurotoxicity and/or (developmental) immunotoxicity (e.g. cholinesterase inhibition or relevant changes in thyroidal hormone levels associated to adverse effects), or
— existing information on effects caused by substances structurally analogous to the substance being studied, suggesting such effects or mechanisms/modes of action.
Other studies on developmental neurotoxicity and/or developmental immunotoxicity instead of cohorts 2A/2B (developmental neurotoxicity) and/or cohort 3 (developmental immunotoxicity) of the Extended One-Generation Reproductive Toxicity Study may be proposed by the registrant in order to clarify the concern on developmental toxicity.

In the 28 day study conducted by MHLW (MHLW 1997) organ weight analyses revealed increases in absolute spleen weights in males receiving 200 mg/kg (but not 400 mg/kg). Slight decreases in absolute spleen weights and absolute and relative thymus weights were noted in males receiving 400 mg/kg. However, there is no dose response relationship concerning the spleen weights and the decreases in thymus weights were not statistically relevant. The histopathological examination of the thymus was unremarkable (spleen not investigated in this study but unremarkable in the Chemie (1988, 1990) study).
Brain weights were not affected up to 400 mg/kg in males and females. Thyroid was not investigated.
In the subacute study reported by BG Chemie (1988, 1990) spleen, thymus, thyroid and brain weights were not examined. Macroscopic examination at necropsy revealed that these organs were not affected by treatment.
In the histopathological examination there were no findings of any unusual nature or incidence suggestive of target organ toxicity (incl. spleen, thymus, thyroid and brain ).
Based on the available data an extension to include the F2 generation or cohorts 2A/2B (developmental neurotoxicity) and/or cohort 3 (developmental immunotoxicity) is not justified.

N,N‘-Dimethylbenzylamin (CAS 103-83-3) is a liquid at room temperature (melting point of -75 °C, boiling point of 180 °C) with a low vapour pressure of 213.57 Pa (20 °C). Therefore, the oral route is the most relevant route of exposure.
Consequently, an extended one-generation reproductive toxicity - basic test design (Cohorts 1A, and 1B without extension) with oral application is proposed.

Since the sub-chronic study and the developmental toxicity study will investigate fertility and developmental endpoints, it is proposed to conduct the studies mentioned in the testing proposals sequentially and to start with the OECD TG 408, afterwards to conduct the OECD TG 414 and finally the OECD TG 443.

Data source

Materials and methods

Test guideline
Qualifier:
according to
Guideline:
OECD Guideline 443 (Extended One-Generation Reproductive Toxicity Study)
Justification for study design:
Since the sub-chronic study and the developmental toxicity study will investigate fertility and developmental endpoints, it is proposed to conduct the studies mentioned in the testing proposals sequentially and to start with the OECD TG 408, afterwards to conduct the OECD TG 414 and finally the OECD TG 443.

The study design of the EOGRTS study will be determined according to the results of the OECD TG 408 and OECD TG 414 study.

According to COMMISSION REGULATION (EU) 2015/282 of 20 February 2015 amending Annexes VIII, IX and X to Regulation (EC) No 1907/2006 of the European Parliament and of the Council on the Registration, Evaluation, Authorisation and Restriction of Chemicals (REACH) as regards the Extended One-Generation Reproductive Toxicity Study in Annex 8.7.3 an Extended One-Generation Reproductive Toxicity Study (B.56 of the Commission Regulation on test methods as specified in Article 13(3) or OECD 443), basic test design (cohorts 1A and 1B without extension to include a F2 generation), one species, most appropriate route of administration, having regard to the likely route of human exposure is a standard information requirement.
An Extended One-Generation Reproductive Toxicity Study with the extension of cohort 1B to include the F2 generation shall be proposed by the registrant or may be required by the Agency in accordance with Article 40 or 41, if:
(a) the substance has uses leading to significant exposure of consumers or professionals, taking into account, inter alia, consumer exposure from articles, and
(b) any of the following conditions are met:
— the substance displays genotoxic effects in somatic cell mutagenicity tests in vivo which could lead to classifying it as Mutagen Category 2, or
— there are indications that the internal dose for the substance and/or any of its metabolites will reach a steady state in the test animals only after an extended exposure, or
— there are indications of one or more relevant modes of action related to endocrine disruption from available in vivo studies or non-animal approaches.

An Extended One-Generation Reproductive Toxicity Study including cohorts 2A/2B (developmental neurotoxicity) and/or cohort 3 (developmental immunotoxicity) shall be proposed by the registrant or may be required by the Agency in accordance with Article 40 or 41, in case of particular concerns on (developmental) neurotoxicity or (developmental) immunotoxicity justified by any of the following:
— existing information on the substance itself derived from relevant available in vivo or non-animal approaches (e.g. abnormalities of the CNS, evidence of adverse effects on the nervous or immune system in studies on adult animals or animals exposed prenatally), or
— specific mechanisms/modes of action of the substance with an association to (developmental) neurotoxicity and/or (developmental) immunotoxicity (e.g. cholinesterase inhibition or relevant changes in thyroidal hormone levels associated to adverse effects), or
— existing information on effects caused by substances structurally analogous to the substance being studied, suggesting such effects or mechanisms/modes of action.
Other studies on developmental neurotoxicity and/or developmental immunotoxicity instead of cohorts 2A/2B (developmental neurotoxicity) and/or cohort 3 (developmental immunotoxicity) of the Extended One-Generation Reproductive Toxicity Study may be proposed by the registrant in order to clarify the concern on developmental toxicity.

In the 28 day study conducted by MHLW (MHLW 1997) organ weight analyses revealed increases in absolute spleen weights in males receiving 200 mg/kg (but not 400 mg/kg). Slight decreases in absolute spleen weights and absolute and relative thymus weights were noted in males receiving 400 mg/kg. However, there is no dose response relationship concerning the spleen weights and the decreases in thymus weights were not statistically relevant. The histopathological examination of the thymus was unremarkable (spleen not investigated in this study but unremarkable in the Chemie (1988, 1990) study).
Brain weights were not affected up to 400 mg/kg in males and females. Thyroid was not investigated.
In the subacute study reported by BG Chemie (1988, 1990) spleen, thymus, thyroid and brain weights were not examined. Macroscopic examination at necropsy revealed that these organs were not affected by treatment.
In the histopathological examination there were no findings of any unusual nature or incidence suggestive of target organ toxicity (incl. spleen, thymus, thyroid and brain ).
Based on the available data an extension to include the F2 generation or cohorts 2A/2B (developmental neurotoxicity) and/or cohort 3 (developmental immunotoxicity) is not justified.

N,N‘-Dimethylbenzylamin (CAS 103-83-3) is a liquid at room temperature (melting point of -75 °C, boiling point of 180 °C) with a low vapour pressure of 213.57 Pa (20 °C). Therefore, the oral route is the most relevant route of exposure.
Consequently, an extended one-generation reproductive toxicity - basic test design (Cohorts 1A, and 1B without extension) with oral application is proposed.

Test material

Reference
Name:
Unnamed
Type:
Constituent
Details on test material:
no data specified

Results and discussion

Applicant's summary and conclusion