Registration Dossier
Registration Dossier
Data platform availability banner - registered substances factsheets
Please be aware that this old REACH registration data factsheet is no longer maintained; it remains frozen as of 19th May 2023.
The new ECHA CHEM database has been released by ECHA, and it now contains all REACH registration data. There are more details on the transition of ECHA's published data to ECHA CHEM here.
Diss Factsheets
Use of this information is subject to copyright laws and may require the permission of the owner of the information, as described in the ECHA Legal Notice.
EC number: 700-330-1 | CAS number: 433733-92-7
- 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
Endpoint summary
Administrative data
Link to relevant study record(s)
- Endpoint:
- basic toxicokinetics
- Type of information:
- other: theoretical approach
- Adequacy of study:
- other information
- Study period:
- January 2009
- Reliability:
- 1 (reliable without restriction)
- Rationale for reliability incl. deficiencies:
- test procedure in accordance with generally accepted scientific standards and described in sufficient detail
- Justification for type of information:
- The compiler evaluated the substance based on available studies.
- Objective of study:
- other: toxicokinetic assessment
- Qualifier:
- no guideline followed
- Principles of method if other than guideline:
- The compiler evaluated the substance based on available studies.
- GLP compliance:
- not specified
- Remarks:
- not applicable
- Radiolabelling:
- other: not applicable
- Preliminary studies:
- See below
- Key result
- Test no.:
- #1
- Observation:
- not determined
- Key result
- Test no.:
- #1
- Toxicokinetic parameters:
- other: not applicable
- Conclusions:
- Interpretation of results: bioaccumulation potential cannot be judged based on study results
For risk assessment purposes the following absorption factors were derived:
oral absorption factor: 50%
dermal absorption factor: 100%
inhalation absorption factor: 50%
Reference
The relatively low molecular weight of Anhydrothymidine (240.2) and high water solubility are favourable for oral absorption. In general, ionisation may impair uptake, since compounds need to pass the lipid membranes in the gastrointestinal wall (1). Since there is no pKa in the logarithm range of 1-12 (calculation), ionisation is not expected. However, log Kow is not favourable for passive diffussion. It is therefore unlikely that Anhydrothymidine will be completely absorbed from the gastrointestinal tract. For risk assessment purposes the oral absorption of Anhydrothymidine is therefore set at 50% as a worst case assumption for route-to-route extrapolation. The results of the toxicity studies do not provide reasons to deviate from this proposed oral absorption factor.
Although the relatively small molecular weight is indicative for wide distribution and high water solubility support diffussion through aqueous channels and pores, the log Pow < 0 (-1.97) is not indicative for distribution into cells. The physical/chemical characteristics are not indicative for bioaccumulation.
Absorbed Anhydrothymidine might undergo Phase I and Phase II biotransformation (2). Because of the high water solubility and the relatively low molecular weight, Anhydrothymidine will be excreted mainly via urine, and possibly also via the bile.
Based on the particle size of Anhydrothymidine, particles with an aerodynamic diameter < 100µm which have the potential to be inhaled, are present (59.71%). Particles with an aerodynamic diameter below 1- 5 µm (0.97% - 7.24%) will settle in the tracheobranchial or pulmonary regions, whereas particles with an aerodynamic diameter above 1 – 5 µm mainly settle in the nasopharyngeal region. The high water solubility of Anhydrothymidine indicates that it will disolve into the mucus lining of the respiratory tract and transported out of the respiratory tract. The log Pow < 0 indicates a low potential for absorption directly across the respiratory tract epithelium. For risk assessment purposes the inhalation absorption of Anhydrothymidine is set at 50% as a worst case assumption.
Anhydrothymidine being a water soluble solid with a moderate molecular weight of 240.2 g/mol has the potential for dermal absorption. However, its high water solubility (797 g/l) and log Pow below -1 (-1.97) do not favour dermal absorption. The physical/chemical parameters do not meet the criteria for 10% dermal absorption as given in the TGD (3) (MW > 500 and log Pow < -1), and therefore 100% dermal absorption as default value has to be taken. It is, however, generally accepted that dermal absorption is lower compared to oral absorption. The 100% dermal absorption derived from physical/chemical properties of the substance should therefore be considered a worst case assumption and for risk assessment purposes a lower dermal absorption value might be more appropriate.
Based on the present available data, no additional conclusions can be drawn on the distribution, metabolism and excretion of Anhydrothymidine after dermal and inhalatory absorption.
References:
1.Amidon GL. Mechanistic approach to understanding the factors affecting drug absorption: a review of fundamentals. J Clin Pharmacol 2002; 42: 620-43.
2. ECB EU Technical Guidance Document on Risk Assessment, 2003
3. A. Parkinson. In: Casarett and Doull’s Toxicology, The basic science of poisons. Sixth edition. Ed. C.D. Klaassen. Chapter 6: Biotransformation of xenobiotics. McGraw-Hill, New York, 2001
Description of key information
Interpretation of results: bioaccumulation potential cannot be judged based on study results
For risk assessment purposes the following absorption factors were derived:
oral absorption factor: 50%
dermal absorption factor: 100%
inhalation absorption factor: 50%
Key value for chemical safety assessment
- Absorption rate - oral (%):
- 50
- Absorption rate - dermal (%):
- 100
- Absorption rate - inhalation (%):
- 50
Additional information
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.