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Please be aware that this old REACH registration data factsheet is no longer maintained; it remains frozen as of 19th May 2023.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

Additional toxicological data

Currently viewing:

Administrative data

additional toxicological information
Type of information:
experimental study
Adequacy of study:
disregarded due to major methodological deficiencies
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Meets generally accepted scientific standards, well documented and acceptable for assessment.

Data source

Reference Type:
Inhibition of mouse testicular DNA synthesis by mutagens and carcinogens as a potential simple mammalian assay for mutagenesis.
Friedman MA and Staub J
Bibliographic source:
Mutat Res 37: 67-76

Materials and methods

Type of study / information:
chemoprevention (inhibition of mutagenicity)
Principles of method if other than guideline:
Male mice were treated orally with NaNO2 either alone or in combination with methylurea. Three hours after treatment, each mouse received [³H]thymidine and was killed 30 minutes later. The testes were removed and homogenized. DNA synthesis was determined as potential indicator in drug evaluation.

Test material

Constituent 1
Chemical structure
Reference substance name:
EC Number:
EC Name:
Cas Number:
Molecular formula:
Details on test material:
- Name of test material (as cited in study report): methylurea
- no data on purity of the compound

Results and discussion

Any other information on results incl. tables

Sodium nitrite and methylurea, when administered alone, induced a slight  inhibition of [3H]thymidine uptake, but not statistically significant  from the control.
However, when administered in combination, both chemicals induced significant inhibition of [3H]thymidine uptake.
Combinations of methylurea (2000 mg/kg) and sodium nitrite (150 mg/kg) administered p.o. resulted in gastric synthesis of nitrosomethylurea and inhibited testicular DNA synthesis by 83%. Combinations of methylurea and sodium nitrite of 1000 and 100 mg/kg respectively inhibited DNA synthesis by 75%.
The non-carcinogenic sodium nitrate (NaNO3) in combination with methylurea had no statistically significant effect.

According to the authors, the importance of inhibition of thymidine uptake as a toxic function of carcinogenic or mutagenic chemicals is difficult to interpret.
This response may not be a mutagenic event but a cytotoxic one. However, since all test substances were active acutely, there also appears to be an S-phase component to their toxicity.

Applicant's summary and conclusion