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Please be aware that this old REACH registration data factsheet is no longer maintained; it remains frozen as of 19th May 2023.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

Genetic toxicity: in vitro

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Administrative data

in vitro cytogenicity / micronucleus study
Type of genotoxicity: genome mutation
Type of information:
experimental study
Adequacy of study:
key study
Study period:
from 2011-07-11 till 2011-11-25
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: Guideline study with GLP and without any deviations.

Data source

Reference Type:
study report
Report date:

Materials and methods

Test guideline
according to guideline
other: OECD guideline 487 for the testing of chemicals: In Vitro Mammalian Cell Micronucleus Test (MNvit); adopted 22 July 2010.
GLP compliance:
yes (incl. QA statement)
Type of assay:
in vitro mammalian cell micronucleus test

Test material

Constituent 1
Chemical structure
Reference substance name:
Methylphosphonic acid, compound with amidinourea (1:1)
EC Number:
EC Name:
Methylphosphonic acid, compound with amidinourea (1:1)
Cas Number:
Molecular formula:
Phosphonic acid, P-methyl-, compd. with N-(aminoiminomethyl)urea (1:1)
Details on test material:
technical product


Target gene:
The assay thus has the potential to detect the activity of both clastogenic and aneugenic chemicals.
Species / strain
Species / strain / cell type:
primary culture, other: binucleated human lymphocytes
Details on mammalian cell type (if applicable):
Blood samples were obtained by venapuncture from a young healthy, non-smoking individual (32 years old) with no known recent exposures to genotoxic chemicals or radiation.
Metabolic activation:
with and without
Metabolic activation system:
S9-mix (based on Aroclor 1254-induced rat liver homogenate (03 March 2010) fraction (S9) and cofactors)
Test concentrations with justification for top dose:
final concentration in the culture medium of 1981 μg/ml (10 mmol/l; limit dose) 1000, 500, 250, 125 and 62.5 μg/ml.
Untreated negative controls:
culture medium
Negative solvent / vehicle controls:
solvent of technical product is water
Positive controls:
Indirect acting positive control (clastogen): Cyclophosphamide; Direct acting positive control (clastogen): Mitomycin C; Aneugenic positive control substance: Vinblastine s
Details on test system and experimental conditions:
In the presence of PHA-L, aliquots of 0.5 ml of whole blood in 4.5 ml culture medium, were incubated for 48 hours at 37ºC in humidified air containing 5% CO2. The incubation was carried out in sterile screw-capped (loose) centrifuge tubes. After the 48-hour incubation period, the cells were exposed to different concentrations of the test substance, in both the presence and absence of the S9-mix.

In the first test, in both the presence and absence of metabolic activation (S9-mix), the treatment time was 4 hours (pulse treatment) and the recovery time 20 hours after the end of treatment. In the second test, in which metabolic activation was absent, the treatment time was 20 hours (continuous treatment) and the recovery time was 28 hours after the end of treatment. In all treatment groups, the cells were exposed to the test substance at concentrations ranging from 62.5 to 1981 μg/ml. In both the first and second test, the maximum final concentration in the culture medium was 1981 μg/ml, which corresponded to 10 mmol/l (i.e. the limit dose). Cytotoxicity was calculated from the Cytokinesis-Block Proliferation Index (CBPI). Based on cytotoxicity, three dose levels were selected for micronuclei analysis. Cyclophosphamide, a clastogenic compound which requires metabolic activation, was used as positive control in the presence of S9-mix. A known clastogenic compound (Mitomycin C) and a known aneugenic compound (Vinblastine sulphate) were used as positive controls in the absence of S9-mix.

Results and discussion

Test results
Species / strain:
Metabolic activation:
with and without
MPAAU was neither clastogenic nor aneugenic to cultured human lymphocytes
Cytotoxicity / choice of top concentrations:
In the 1st test (w/wo S9-mix) and in the 2nd test (wo S9-mix) the test substance was only slightly toxic (10% and 15%, respectively) to the cells at the highest dose level (1981 µg/ml, 10 mmolar, limit concentration) analysed.
Vehicle controls validity:
not applicable
Untreated negative controls validity:
Positive controls validity:
Remarks on result:
other: strain/cell type: binucleated human lymphocytes
Migrated from field 'Test system'.

Applicant's summary and conclusion

Interpretation of results (migrated information):
negative w/wo metabolic activation

From the results obtained in two in vitro micronucleus tests it is concluded that, under the conditions used in this study, the test substance MPAAU was neither clastogenic nor aneugenic to cultured human lymphocytes.