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:
Following a decision of the EU Ombudsman of 11 September 2015 (1606/2013/AN), ECHA has been separately requesting companies who propose tests involving vertebrate animals to show that they have fully considered alternative methods before concluding that a new animal test is necessary. This means that after 21 June 2017, a dossier with a proposal to test on vertebrate animals needs to have documented considerations of alternatives for each proposed vertebrate study to pass the completeness check.

TESTING PROPOSAL ON VERTEBRATE ANIMALS

NON-CONFIDENTIAL NAME OF SUBSTANCE:
- Name of the substance on which testing is proposed to be carried out: Dimethylamine (CAS 124-40-3)
- Name of the substance for which the testing proposal will be used: Dimethylamine (CAS 124-40-3)

CONSIDERATIONS THAT THE GENERAL ADAPTATION POSSIBILITIES OF ANNEX XI OF THE REACH REGULATION ARE NOT ADEQUATE TO GENERATE THE NECESSARY INFORMATION:
- Available GLP studies: there are no GLP studies concerning Toxicity to reproduction available.
- Available non-GLP studies: there are no GLP studies concerning Toxicity to reproduction available.
- Historical human data: there is only limited information in humans available (supporting study in section developmental toxicity/ teratogenicity dealing with human milk)
- (Q)SAR: there are no QSARs concerning the toxicity to reproduction available for dimethylamine or its read-across substances.
- In vitro methods: there are no in vitro results available for the endpoint toxicity to reproduction for dimethylamine or its read-across substances
- Weight of evidence: there are no weight-of-evidence data available for the endpoint toxicity to reproduction for dimethylamine or its read-across substances.
- Grouping and read-across: there are no grouping or read-across data available for dimethylamine or its read-across substances for the endpoint toxicity to reproduction. Only in section developmental toxicity / teratogenicity there is data available for the read-across substance DMA-HCl which is here used as supporting data in addition to the key studies undertaken with the test substance dimethylamine.
- Substance-tailored exposure driven testing: not applicable
- Approaches in addition to above: not applicable
- Other reasons: 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 animal derived data available addressing the toxicity to reproduction of dimethylamine (no GLP, no non-GLP). Furthermore, there is only limited historical human data available. In detail, this refers to one existing publication investigating volatile aliphatic amines in both human breast milk and preterm and term amniotic fluid. Although the evidence presently is indirect and does not establish a causal relationship between gastric amines and circulating gastrin levels in newborn infants, the data does support the possibility that the presence of these amino acid metabolites in the stomach may contribute to the hypergastrinemia recorded in the developing fetus / neonate during the periods before and after parturition. This information is, however, not suitable to fulfill the requirements, as it dose not provide information on possible associations between exposure to a chemical and adverse effects on reproduction. In addition, there is no data derived from dimethylamine itself or suitable read-across substances which can be used in a weight-of-evidence approach to fulfill the requirements for toxicity to reproduction. Neither QSAR approaches nor in vitro methods are available which might have been suitable to be used to fulfill the requirements for this endpoint. However, the available methods are currently anyways not sufficient to address the complex endpoints on reproductive toxicity to replace an animal test and are in general only useful to support grouping and read-across approaches or to be used in an weight-of-evidence approach. Finally, there is no data available for the read-across substances (the methylamines Monomethylamine (MMA) and Trimethylamine (TMA), which allow "vertical" read-across, the ethyl analogues Diethylamine (DEA, CAS 109-89-7), Diisopropylamine (DIPA, CAS 108-18-9), Dibutylamine (DBA, CAS 111-92-2) and Dipropylamine (DPeA, CAS 2050-92-2) which allow “horizontal” read-across). Therefore, as none of the general and specific adaption rules in column 2 provide possibilities for omitting the testing and testing is technically feasible, there is no other option to adequately fulfill the requirements than to conduct the extended one generation reproductive toxicity study with dimethylamine.

FURTHER INFORMATION ON TESTING PROPOSAL IN ADDITION TO INFORMATION PROVIDED IN THE MATERIALS AND METHODS SECTION:
- Details on study design / methodology proposed: The registrants propose the following EOGRTS study design:
- Test animals: rats
- Exposure route: inhalation (gas) as the inhalative route of exposure will be more suitable for gaseous members of the alkyl amine category or category members with short alkyl chains. Furthermore, the testing conditions shall also reflect the most likely and most relevant exposure routes as much as possible.
- Premating exposure duration 10 weeks to cover the full spermatogenesis and folliculogenesis before the mating
- Dose selection based on a dose range finder
- Basic design with Cohort 1 A and 1B (without extended reproduction toxicity cohort 1B as the conditions for this are not met, please refer to the justification given below "Justification of study design")
- Exclusion of the developmental neurotoxicity Cohorts 2A and 2B, as the conditions for this are not met, please refer to the justification given below under"Justification of study design".
- Exclusion of the developmental immunotoxicity Cohort 3, as the conditions for this are not met, please refer to the justification given below under "Justification of study design".
- However, the registrants may expand the study after initiation base on new information indicating a concern which needs to be addressed. The justification for the expansion must be documented.

Data source

Materials and methods

Test guidelineopen allclose all
Qualifier:
according to
Guideline:
OECD Guideline 443 (Extended One-Generation Reproductive Toxicity Study)
Qualifier:
according to
Guideline:
EU Method B.56 (Extended One-Generation Reproductive Toxicity Study)
GLP compliance:
yes
Limit test:
no
Justification for study design:
SPECIFICATION OF STUDY DESIGN FOR EXTENDED ONE-GENERATION REPRODUCTION TOXICITY STUDY WITH JUSTIFICATIONS:

- Premating exposure duration for parental (P0) animals: 10 weeks (according to ECHA Guidance, the starting point for deciding on the length of premating exposure period should be ten weeks to cover the full spermatogenesis and folliculogenesis before the mating, allowing meaningful assessment of the effects on fertility)
- Basis for dose level selection: preliminary dose range finder (the highest dose level shall aim to induce some toxicity to allow comparison of effect levels and effects of reproductive toxicity with those of systemic toxicity)
- exclusion of extension of Cohort 1B (the conditions to include the extension of Cohort 1B are currently not met (please also refer to the summary of effects observed depicted below)
- Termination time for F2: not applicable
- exclusion of developmental neurotoxicity Cohorts 2A and 2B (No triggers for the inclusion of Cohorts 2A and 2B (developmental neurotoxicity) were identified, please also refer to the summary of effects observed depicted below)
- exclusion of developmental immunotoxicity Cohort 3 (No triggers for the inclusion of Cohort 3 (developmental immunotoxicity) were identified, please also refer to the summary of effects observed depicted below)
- Route of administration: inhalation (gas)
- Other considerations, e.g. on choice of species, strain, vehicle and number of animals: not applicable


Background information used to conclude on the study design:
- Uses and exposure assessment for professional workers and consumers: no consumer uses identified, several professional uses identified, which do not lead to significant exposure
- Genotoxicity: the substance has been shown to be not genotoxic (negative results in a bacterial reverse mutation assay (Ames test); negative results in an multiple-endpoint mutagenesis test with Chinese hamster ovary cells; negatvie results In an in vivo Mammalian Chromosome Aberration Assay; and in conclusion no classification as mutagenic)
- Bioaccumulaiton: there are no indications that an extended exposure durcation is needed to reach the steady state kinetics, as the substance has been shown to have a very low potential for bioaccumulation in aquatic and terrestrial organisms. The very low Bioconcentration factor (BCF = 3.2), derived based on an octanol-water coefficient of only -0.71 (BASF, 1988), clearly shows that persistence of the test substance in environmental compartments or organisms can be ruled out.
- Repeated-dose toxicity: The olfactory sensory cell is highly sensitive to the toxic effects of DMA, with minor lesions being produced in rodents even at the current threshold limit value of 10 ppm. A LOAEC can be set at 10 ppm (18.7 mg/m³), since only a few animals were affected with slight alterations.
- Neurotoxicity: there is no data avaialble which rises a concern for dimethylamine and its potential to induce neurotoxicity (please also refer to the summary of effects observed depicted below)
- Immunotoxicity: there is no data avaialble which rises a concern for dimethylamine and its potential to induce immunotoxicity (please also refer to the summary of effects observed depicted below)
- Endocrine effects and modes of action: there is no data available which rises a concern for dimethylamine and its potential to induce endocrine effects (please also refer to the summary of effects observed depicted below). The available repeated dose toxicity and reproductive toxicity studies do not provide indication of endocrine disrupting modes of action. Furthermore, no data rising concerns related to endocrine disruption is available which is derived from in vivo assays, from non-animal approaches for prediction to (endocrine disrupting modes of action, from eco-toxicity testing for predicting endocrine (disrupting) modes of action.

The available results for dimethylamine and its read-across substances can be summarised as follows:
The results of two chronic inhalation studies and two recent GLP guideline developmental studies showed that the target substance does not to produce adverse effects on reproductive organs or tissues and therefore no concern exists in relation with reproductive performance. In details, the toxicity of Dimethylamine was investigated in F-344 rats and B6C3F1 mice following a one-year inhalation exposure to 0, 10, 50, or 175 ppm (Buckley et al., 1985). After 6 or 12 month exposure period, animals were sacrificed and their organs and tissues, including reproductive organs, were examined for gross abnormalities. Any gross lesions were then collected and examined histopathologically. The only treatment-related changes were concentration-related lesions in the nasal passages: the respiratory epithelium and olfactory epithelium. The study results were confirmed by another chronic two-year inhalation study in F-344 rats (Gross et al., 1987). The only treatment-related lesions were abnormalities related to destruction of the nasal tissues. In the OECD 414 drinking water study conducted with Dimethyl hydrochloride (CAS 506-59-2) and rats, the NOAEL for maternal toxicity was 300 mg/kg bw/d, mid dose, based on decreased food consumption and salivation after treatment in the high dose dams (1000 mg/kg bw/d) (BASF, 2009). No test substance-related and/or biologically relevant differences with regard to conception rate, mean number of corpora lutea, implantation sites, pre- and postimplantation loss and resorptions (total, early and late) were observed. At necropsy, no test substance-related findings were observed in the dams. Reproductive organs examined grossly were similar to those of controls. The NOAEL for prenatal developmental toxicity was 1000 mg/kg bw/d because there was no evidence of an adverse effect of the test compound on fetal morphology. In the OECD 414 inhalation study with Dimethylamine and rabbits, there were no treatment-related effects on reproductive performance and morphology and histology of reproductive organs of dams (WIL Research, 2016). Gravid uterine weights in all treatment groups were similar to controls. Intrauterine growth and survival were unaffected by test substance exposure at all exposure levels. Parameters evaluated included post implantation loss, live litter size, mean fetal body weights, and fetal sex ratios. Mean numbers of corpora lutea and implantation sites were similar across all groups.

Test material

Reference
Name:
Unnamed
Test material form:
gas

Test animals

Species:
rat
Sex:
male/female

Administration / exposure

Route of administration:
inhalation: gas

Results and discussion

Applicant's summary and conclusion