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EC number: 269-929-9 | CAS number: 68391-11-7 The complex combination of polyalkylated pyridines derived from coal tar distillation or as high-boiling distillates approximately above 150°C (302°F) from the reaction of ammonia with acetaldehyde, formaldehyde or paraformaldehyde.
- Life Cycle description
- Uses advised against
- Endpoint summary
- Appearance / physical state / colour
- Melting point / freezing point
- Boiling point
- Density
- Particle size distribution (Granulometry)
- Vapour pressure
- Partition coefficient
- Water solubility
- Solubility in organic solvents / fat solubility
- Surface tension
- Flash point
- Auto flammability
- Flammability
- Explosiveness
- Oxidising properties
- Oxidation reduction potential
- Stability in organic solvents and identity of relevant degradation products
- Storage stability and reactivity towards container material
- Stability: thermal, sunlight, metals
- pH
- Dissociation constant
- Viscosity
- Additional physico-chemical information
- Additional physico-chemical properties of nanomaterials
- Nanomaterial agglomeration / aggregation
- Nanomaterial crystalline phase
- Nanomaterial crystallite and grain size
- Nanomaterial aspect ratio / shape
- Nanomaterial specific surface area
- Nanomaterial Zeta potential
- Nanomaterial surface chemistry
- Nanomaterial dustiness
- Nanomaterial porosity
- Nanomaterial pour density
- Nanomaterial photocatalytic activity
- Nanomaterial radical formation potential
- Nanomaterial catalytic activity
- Endpoint summary
- Stability
- Biodegradation
- Bioaccumulation
- Transport and distribution
- Environmental data
- Additional information on environmental fate and behaviour
- Ecotoxicological Summary
- Aquatic toxicity
- Endpoint summary
- Short-term toxicity to fish
- Long-term toxicity to fish
- Short-term toxicity to aquatic invertebrates
- Long-term toxicity to aquatic invertebrates
- Toxicity to aquatic algae and cyanobacteria
- Toxicity to aquatic plants other than algae
- Toxicity to microorganisms
- Endocrine disrupter testing in aquatic vertebrates – in vivo
- Toxicity to other aquatic organisms
- Sediment toxicity
- Terrestrial toxicity
- Biological effects monitoring
- Biotransformation and kinetics
- Additional ecotoxological information
- Toxicological Summary
- Toxicokinetics, metabolism and distribution
- Acute Toxicity
- Irritation / corrosion
- Sensitisation
- Repeated dose toxicity
- Genetic toxicity
- Carcinogenicity
- Toxicity to reproduction
- Specific investigations
- Exposure related observations in humans
- Toxic effects on livestock and pets
- Additional toxicological data
Basic toxicokinetics
Administrative data
- Endpoint:
- basic toxicokinetics
- Type of information:
- other: Expert Statement
- Adequacy of study:
- key study
- Reliability:
- 2 (reliable with restrictions)
- Rationale for reliability incl. deficiencies:
- other: see 'Remark'
- Remarks:
- Read-across from supporting substance Substance: 5-ethyl-2-methylpyridine CAS no.: 104-90-5 EC no.: 203-250-0 Read-across justification Pyridine, alkyl derivatives is a substance of Unknown or Variable Composition, Complex Reaction Products, or Biological Materials (UVCB, subtype 2). The substance is not a discrete chemical, but characterized by a variety of structures. The substance 2-ethyl-4-methylpyridine (CAS no. 26091-11-2) and its isomer 5-ethyl-2-methylpyridine (MEP, CAS no. 104-90-5) were selected as representative model structures (Environment Canada, 2011). Both model structures are major constituents of Pyridine, alkyl derivatives. All are high-boiling distillates above 150 °C. Using 1,3,5-Trioxane, 2,4,6-trimethyl- (Paracetaldehyde, CAS no. 123-63-7) and Ammonia (CAS no. 7664-41-7) as starting materials the substances are produced in a Acetic acid (CAS no. 64-19-7) catalyzed fluid-phase reaction. Whilst Pyridine, alkyl derivatives result directly from the reaction, the two model constituents are isolated by further extraction and purification. Compared to the UVCB substance the selected structures show similar physical-chemical, toxicological and ecotoxicological properties. Most characteristically is the high boiling point > 170 °C. A data matrix covering all available endpoints was previously published and is included in section 13 (Environment Canada, 2011). The available data on the UVCB substance and selected model constituents reveals similar properties. In general, the classification and labeling of the model constituents is comparable to that of the UVCB substance. Neither the model constituents nor the UVCB substance are considered PBT or vPvB substances. In summary, the read-across between the UVCB substance and the model constituent MEP is justified.
Data source
Reference
- Reference Type:
- other: Expert statement
- Title:
- Unnamed
- Report date:
- 2012
Materials and methods
Test guideline
- Qualifier:
- no guideline required
- Principles of method if other than guideline:
- Assessment of the toxicokinetic behavior of the substance to the extent that can be derived from the relevant available information.
- GLP compliance:
- no
Test material
- Test material form:
- gas under pressure: refrigerated liquefied gas
- Details on test material:
- - Name of test material: Pyridine, alkyl derivs.
Constituent 1
- Radiolabelling:
- no
Results and discussion
Toxicokinetic / pharmacokinetic studies
- Details on absorption:
- 5 Ethyl 2 methylpyridine is a colorless, clear liquid with characteristic, unpleasant odor. The substance has a molecular weight of 121.18 g/mol, exerts a vapor pressure of 1.853 hPa at 20 °C, a log Pow of 2.1 and is very soluble in water with 12000 mg/L at 20 °C. Based on the determined vapor pressure the substance may volatilize and thus be potentially inhaled as a vapor. However, the very high water solubility, relatively low log octanol water partition coefficient and low molecular weight suggest greater potential for absorption across the skin and gastrointestinal tract.
Upon oral administration uptake of 5-Ethyl-2-methylpyridine is limited by its potential for ionization in neutral and acidic environments (pKa = 6.51). However, due to its low molecular weight and high water solubility the substance has potential to pass through aqueous pores or passage across membranes, e.g. with the bulk passage of water. Based on the results obtained in acute oral toxicity testing (LD50 = 710 mg/kg bw) absorption may occur.
Following inhalation of vapor or aerosols 5-Ethyl-2-methylpyridine may be absorbed directly across the respiratory tract epithelium. Due to the high water solubility and low molecular weight there is also potential for absorption through aqueous pores. Based on the inhalation toxicity data (2.67 mg/L) absorption via the lungs may occur.
Upon exposure to the skin the substance ionization may limit passage across biological membranes. However, the substance has some potential for dermal absorption due to its high water solubility and logPow of 2.39. Based on the acute dermal toxicity data dermal absorption may occur. - Details on distribution in tissues:
- Following uptake and becoming bioavailable 5-Ethyl-2-methylpyridine and its metabolites are likely to distribute throughout the blood and intracellular compartments of the organism. Distribution may be limited by the rate of diffusion across membranes. No specific target tissue is known. Based on logPow and the calculated bioaccumulation factor (BCF = 1.244, Epiwin, v4.0) bioaccumulation is not expected.
- Details on excretion:
- Based on its molecular weight, water solubility and pKa the parent compound 5-Ethyl-2-methylpyridine is likely to be excreted via the urine. Depending on the degree of conjugation, some metabolites may be excreted via bile and faeces. However, the likely predominant pathway for excretion is urine.
Metabolite characterisation studies
- Metabolites identified:
- no
- Details on metabolites:
- There is no experimental data on the metabolism of 5-Ethyl-2-methylpyridine. Phase I reactions catalysed by cytochrome P450 or flavin containing monooxygenase may introduce polar groups into the molecule. Phase II conjugation reactions may add charged species such as glutathione (GSH), sulfate, glycine, or glucuronic acid, rendering the molecule less toxic. Based on data available for pyridine and alkylpridines, oxidation of the nitrogen atom and all the carbon atoms of the pyridine ring are likely. Further, heterocyclic nitrogen atoms can be candidates for methylation and, thus, N-methylation, even though less common, may also occur.
It is unlikely that metabolism will render the parent compound or its degradation products more toxic. This assumption is supported by results obtained in a sub-acute repeated dose toxicity test as well as an in vitro Ames test, two chromosome aberration tests and a HPRT assay without and with metabolic activation. In all three assays no significant increases in toxicity were noted, in the presence of a rodent microsomal S9-fraction. This clearly indicates that formation of reactive metabolites is unlikely.
Applicant's summary and conclusion
- Conclusions:
- Interpretation of results (migrated information): no bioaccumulation potential based on study results
The main routes of exposure for 5-Ethyl-2-methylpyridine are through inhalation of vapors and skin/eye contact with liquid. Following uptake the parent compound and its metabolites may be distributed throughout the organism. Bioaccumulation is considered not likely. Metabolism may render the substance more polar and less toxic before excretion. There is no indication for the formation of more toxic metabolites. Elimination of parent and degradation products is most likely via urine and to a lesser extent via bile and faeces. - Executive summary:
The toxicokinetic assessment was carried out with 5-ethyl-2-methylpyridine (MEP, CAS no.: 104-90-5, EC no.: 203-250-0). The read-across between the UVCB substance and the model constituent is justified. The toxicokinetic behavior of the substance was assessed to the extent that can be derived from the relevant available information. The main routes of exposure for 5-Ethyl-2-methylpyridine are through inhalation of vapors and skin/eye contact with liquid. Following uptake the parent compound and its metabolites may be distributed throughout the organism. Bioaccumulation is considered not likely. Metabolism may render the substance more polar and less toxic before excretion. There is no indication for the formation of more toxic metabolites. Elimination of parent and degradation products is most likely via urine and to a lesser extent via bile and faeces.
Information on Registered Substances comes from registration dossiers which have been assigned a registration number. The assignment of a registration number does however not guarantee that the information in the dossier is correct or that the dossier is compliant with Regulation (EC) No 1907/2006 (the REACH Regulation). This information has not been reviewed or verified by the Agency or any other authority. The content is subject to change without prior notice.
Reproduction or further distribution of this information may be subject to copyright protection. Use of the information without obtaining the permission from the owner(s) of the respective information might violate the rights of the owner.
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