Urea

Genetic toxicity: in vivo

Administrative data

Endpoint:

in vivo mammalian somatic cell study: cytogenicity / bone marrow chromosome aberration

Type of information:

experimental study

Adequacy of study:

supporting study

Reliability:

3 (not reliable)

Rationale for reliability incl. deficiencies:

other: Published study; non-standard method. The study is poorly reported and its value/relevance l imited by the extreme dose level used, which is well in excess of the currently accepted limit dose.

Data source

Reference

Reference 1

Reference Type:

publication

Title:

Randomness of chromosome breaks in bone marrow cells of fertilizer-fed mice, Mus musculus.

Author:

Chaurasia O.P.

Year:

1991

Bibliographic source:

Cytobios 67(268):7–12.

Reference 2

Reference Type:

review article or handbook

Title:

Toxicological review of urea (CAS No. 57-13-6) In support of Summary Information on the Integrated Risk Information System (IRIS)

Author:

U.S. Environmental Protection Agency

Year:

2011

Materials and methods

GLP compliance:

not specified

Type of assay:

mammalian bone marrow chromosome aberration test

Test material

Test material information

Constituent 1

Reference substance name:

Urea

EC Number:

200-315-5

EC Name:

Urea

Cas Number:

57-13-6

Molecular formula:

CH4N2O

IUPAC Name:

urea

Details on test material:

It is assumed that the purity is 100%

Test animals

Species:

mouse

Strain:

Swiss

Remarks:

albino (Mus musculus)

Sex:

male

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Age at study initiation: 7-to 10-week-old

Administration / exposure

Route of administration:

oral: feed

Duration of treatment / exposure:

5-7 days

Frequency of treatment:

daily

Post exposure period:

Bone marrow samples were collected seven days after the last treatment.

Doses / concentrations

Dose / conc.:

500 other: mg/kg-day

Remarks:

fed with urea (500 mg/kg-day) for 5–7 days

Examinations

Tissues and cell types examined:

bone marrow

Results and discussion

Test results

Sex:

male

Genotoxicity:

positive

Remarks on result:

other: urea was capable of inducing chromosome aberrations

Applicant's summary and conclusion

Conclusions:

Chaurasia (1991) and Chaurasia and Sinha (1987) conducted in vivo experiments in 7-to 10-week-old male Swiss albino mice fed with urea (500 mg/kg-day) for 5–7 days. Bone marrow samples were collected seven days after the last treatment and a minimum of 100 metaphases were examined. Both studies showed that urea was capable of inducing chromosome aberrations (CA). Among several types of CA found, chromatid breaks were the most frequent. The authors concluded that urea may be a potent clastogen.

Executive summary:

Urea induced chromosome and chromatid breaks in the metaphase chromosomes of bone marrow cells of fertilizer-fed Swiss albino mice, Mus musculus. The breaks caused by urea were non-randomly distributed, since they were more frequent in the longer chromosomes than in the smaller ones, and more common in the distal region than in the juxtacentrometric and median regions.