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Diss Factsheets
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EC number: 200-070-4 | CAS number: 50-89-5
- 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
![](https://echa.europa.eu/o/diss-blank-theme/images/factsheets/A-REACH/factsheet/print_toxicological-information.png)
Repeated dose toxicity: oral
Administrative data
- Endpoint:
- sub-chronic toxicity: oral
- Type of information:
- migrated information: read-across from supporting substance (structural analogue or surrogate)
- Adequacy of study:
- key study
- Reliability:
- 2 (reliable with restrictions)
- Rationale for reliability incl. deficiencies:
- other: See read-across justification attached.
Data source
Reference
- Reference Type:
- publication
- Title:
- Unnamed
- Year:
- 2 007
Materials and methods
Test guideline
- Qualifier:
- equivalent or similar to guideline
- Guideline:
- OECD Guideline 408 (Repeated Dose 90-Day Oral Toxicity Study in Rodents)
- Deviations:
- no
- GLP compliance:
- yes
- Limit test:
- no
Test material
- Test material form:
- solid: crystalline
- Details on test material:
- - Name of test material: L-Thymidine
Constituent 1
Test animals
- Species:
- rat
- Strain:
- other: Crl:CD(SD) BR
- Sex:
- male/female
Administration / exposure
- Route of administration:
- oral: gavage
- Vehicle:
- CMC (carboxymethyl cellulose)
- Remarks:
- 0.5 % (wt/vol)
- Duration of treatment / exposure:
- Six month treatment with three month interim sacrifice and one month recovery groups (control and high dose group)
- Frequency of treatment:
- Daily
Doses / concentrations
- Remarks:
- Doses / Concentrations:
0, 250, 500, 1000 mg/kg bw/day
Basis:
actual ingested
- No. of animals per sex per dose:
- 10/sex/group for control and treatment groups and 5/sex/recovery group
- Control animals:
- yes, concurrent vehicle
Examinations
- Observations and examinations performed and frequency:
- Repeat-dose toxicity was evaluated based on mortality; clinical observations; body weight; food consumption; ophthalmology; clinical pathology, including hematology, coagulation, and chemistry; and/or macroscopic and microscopic pathology.
- Sacrifice and pathology:
- GROSS PATHOLOGY: Yes
HISTOPATHOLOGY: Yes
Results and discussion
Results of examinations
- Clinical signs:
- no effects observed
- Mortality:
- no mortality observed
- Body weight and weight changes:
- no effects observed
- Food efficiency:
- no effects observed
- Ophthalmological findings:
- no effects observed
- Haematological findings:
- no effects observed
- Clinical biochemistry findings:
- no effects observed
- Organ weight findings including organ / body weight ratios:
- no effects observed
- Gross pathological findings:
- no effects observed
- Histopathological findings: non-neoplastic:
- no effects observed
- Details on results:
- In the 6-month repeat-dose toxicity study with 3-month interim sacrifice in rats, six rats in total were found dead (one control male, two males dosed at 500 mg/kg/day, and two females dosed at 1,000 mg/kg/day) or sacrificed for humane reasons (one male dosed at 1,000 mg/kg/day). Except for one male dosed at 500 mg/kg/day that was found dead on day 161 and whose cause of death was undetermined, the cause of death for the remaining four rats was considered to be gavage related. The male dosed at 1,000 mg/kg/day that was sacrificed for humane reasons on study day 133 was diagnosed with widespread lymphoma, a common spontaneous tumor. None of these deaths was attributed to the test item. Treatment had no adverse effects on food consumption, but some dosed rats had intervals of increased food intake. This transient increased appetite was not considered evidence for toxicity from the test item. Ophthalmic examinations of rats in all dose groups did not identify any treatment-related changes; there were some age-related changes. Hematology data did not indicate toxicity from the test item after 92 days (3 months), 176 days (6 months), or 204 days (1-month recovery). There were no conclusive findings from the clinical chemistry data to indicate evidence for toxicity at any interval. Mean absolute and relative organ weights were somewhat variable but failed to demonstrate a clear pattern for toxicity from the test item. No macroscopic or microscopic morphological changes were associated with test item exposure. The NOAEL was reported to be 1,000 mg/kg/day.
Effect levels
- Dose descriptor:
- NOAEL
- Effect level:
- 1 000 mg/kg bw/day (nominal)
- Based on:
- test mat.
- Sex:
- male/female
- Basis for effect level:
- other: No treatment related adverse effects observed up to the highest dose (limit dose) tested.
Target system / organ toxicity
- Critical effects observed:
- not specified
Applicant's summary and conclusion
- Conclusions:
- No treatment related adverse effects were noted in this 6-month repeat-dose toxicity study with 3-month interim sacrifice in rats, including recovery groups. The NOAEL for males and females was determined to be 1000 mg/kg bw/day (limit dose).
- Executive summary:
A study was carried out similar or equivalent to OECD Guideline 408 (Repeated Dose 90-Day Oral Toxicity in Rodents) using L-Thymidine. The read-across approach to the L-isomer of the nucleoside is justified.
A total of 10 males and 10 females was dosed at 0, 250, 500 and 1000 mg/kg bw/day (up to the limit dose) for six month with three month interim sacrifice and one month recovery groups (control and high dose group). Repeat-dose toxicity was evaluated based on mortality; clinical observations; body weight; food consumption; ophthalmology; clinical pathology, including hematology, coagulation, and chemistry; and/or macroscopic and microscopic pathology.
In the 6-month repeat-dose toxicity study with 3-month interim sacrifice in rats, none of the observed deaths was attributed to the test item. Treatment had no adverse effects on food consumption, but some dosed rats had intervals of increased food intake. Ophthalmic examinations of rats in all dose groups did not identify any treatment-related changes. Hematology data did not indicate toxicity from the test item after 92 days (3 months), 176 days (6 months), or 204 days (1-month recovery). There were no conclusive findings from the clinical chemistry data to indicate evidence for toxicity at any interval. Mean absolute and relative organ weights were somewhat variable but failed to demonstrate a clear pattern for toxicity from the test item. No macroscopic or microscopic morphological changes were associated with test item exposure. The NOAEL was determined to be 1000 mg/kg/day.
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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