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Please be aware that this old REACH registration data factsheet is no longer maintained; it remains frozen as of 19th May 2023.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

Toxicological information

Toxicity to reproduction: other studies

Currently viewing:

Administrative data

toxicity to reproduction: other studies
Type of information:
experimental study
Adequacy of study:
other information
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
study well documented, meets generally accepted scientific principles, acceptable for assessment

Data source

Reference Type:
Tellurium-induced neuropathy: a model for reversible reductions in myelin protein gene expression
Toews A.D., Lee S.Y., Popko B. and Morell P.
Bibliographic source:
Journal of Neuroscience Research 26:501-507.

Materials and methods

Principles of method if other than guideline:
- Principle of test: rat model to study temporaly demyeinisation of periferial nerves, followed by a period of rapid remyelinisation.
- Short description of test conditions: pre-pubertal rats are fed for 7 days Te-supplemented chow, and followed up for 30 days.
- Parameters analysed / observed: RNA isolation and analysis for myelin-specific proteins (Po and MBP)
GLP compliance:
Type of method:
in vivo

Test material

Specific details on test material used for the study:
elemental tellurium powder (60 mesh, Alfa Products, Davers , MA, USA)

Test animals

Details on test animals or test system and environmental conditions:
Animals were weaned at day 17 and exposed to tellurium from day 20-27 (7 days)
The animals were kept in rooms at constant temeperature of 21+/-2°C, with relative humidity of 50+/-10%, with a 12h light /dark cycle.

Administration / exposure

Route of administration:
oral: feed
Details on exposure:
Purina milled rodent chaw was mixed with 1.1% Tellurium by weight containing some corn oil to prevent separation.
The supplemented chaw was availbable ad libitum from Day 20 fro 7 days.,
Duration of treatment / exposure:
7 days
Frequency of treatment:
continous availibility ad libitum.
Duration of test:
30 days + first 7 days exposure.
No. of animals per sex per dose:
4-9 animals / for each evaluation point ( = day 1, 3, 5, 9, 15 and 30)
Control animals:
yes, concurrent vehicle
Details on study design:
Animals were exposed for 7 days and tissue as retreived for analysis on day 1, 3, 5, 9, 15 and 30.

Three separate groups of samples, each derived from separate groups of 7-8 litters, were analyzed.
At each time point, sciatic nerves (that portion distal to the L5 dorsal root ganglion and proximal to the popliteal fossa) were excised and the epineurial/perineurial sheath was removed and discarded; the remaining endoneurial tissue was immediatelyfrozen.
For analysis nerves from 4-9 rats were pooled.

Results and discussion

Observed effects

Exposure to tellurium resulted in a marked increasein total RNA in sciatic nerve. Levels were near normal after 1 day of tellurium exposure but were elevated approximately 3- to 4-fold after 5 days of tellurium exposure. Total RNA levels subsequently decreased and were near normal by 15 days following initiation of tel- lurium exposure.
Most of the increase in total RNA could be accounted for by ribosomal RNA,

Any other information on results incl. tables

Although tellurium blocks cholesterol synthesis in all tissues, including brain, demyelination occurs only in the PNS. Levels of mRNA for MBP did not decrease in brain stem (there was actually a slight increase) as a consequence of exposure to tellurium, indicating that the decreased message levels for myelin proteins seen in sciatic nerve are not the direct result of inhibition of cholesterol synthesis or accumulation of squalene.

Applicant's summary and conclusion

From this paper only the relevant information and results, that could have an impact on the reproductive function are included in this summary.

This study does give any evidence that tellurium might impair the reproductive toxicity function.
Executive summary:

The authours suggest that the sequence of metabolic events in sciatic nerve following tellurium treatment initially involves inhibition of the conversion of squalene to 2,3-epoxysqualene, and that this block in the cholesterol biosynthesis pathway results, either directly or indirectly, in the inhibition of the synthesis of myelin components and breakdown of myelin

But although cholesterol is a precursor for steroid production in the gonads, denovo synthesis is not the rate limiting step in steroidogenesis as cholesterol can be obtained from other sources.