Butyl carbamate

Genetic toxicity: in vivo

Administrative data

Endpoint:

in vivo mammalian somatic cell study: cytogenicity / erythrocyte micronucleus

Type of information:

experimental study

Adequacy of study:

key study

Study period:

5 Feb 2020 - 23 March 2020

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2020

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 474 (Mammalian Erythrocyte Micronucleus Test)

Version / remarks:

2016

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Type of assay:

mammalian erythrocyte micronucleus test

Test material

Test material information

Constituent 1

Reference substance name:

Butyl carbamate

EC Number:

209-751-0

EC Name:

Butyl carbamate

Cas Number:

592-35-8

Molecular formula:

C5H11NO2

IUPAC Name:

butyl carbamate

Test material form:

liquid

Test animals

Species:

mouse

Strain:

NMRI

Details on species / strain selection:

source: Charles River Laboratories, Sulzfeld, Germany

Sex:

female

Details on test animals or test system and environmental conditions:

Housing: single
Cage Type: Makrolon Type II / III, with wire mesh top
Bedding: granulated soft wood bedding
Feed: 2018C Teklad Global 18% protein rodent diet
(certified), ad libitum
Water: tap water, ad libitum
Environment: temperature 22 + 2°C
relative humidity approx. 45-65%
artificial light 6.00 a.m. - 6.00 p.m.
ventilation: at least eight air changes per hour

Administration / exposure

Route of administration:

oral: gavage

Vehicle:

PEG 400

Details on exposure:

The animals received the test item, the vehicle or the positive control item once orally

Duration of treatment / exposure:

once by gavage

Frequency of treatment:

single administration

Post exposure period:

24 and 48 h

Doses / concentrations

Doses / concentrations 1

Dose / conc.:

0 mg/kg bw (total dose)

Remarks:

negative control

Doses / concentrations 2

Dose / conc.:

125 mg/kg bw (total dose)

Remarks:

low dose group

Doses / concentrations 3

Dose / conc.:

250 mg/kg bw (total dose)

Remarks:

mid dose group

Doses / concentrations 4

Dose / conc.:

500 mg/kg bw (total dose)

Remarks:

high dose group

No. of animals per sex per dose:

6 females

Control animals:

yes, concurrent vehicle

Positive control(s):

40 mg/kg bw Cyclophosphamide

Examinations

Tissues and cell types examined:

Evaluation of the slides was performed using NIKON microscopes with 100x oil immersion objectives. At least 4000 polychromatic erythrocytes (PCE) per animal were analysed for micronuclei. To describe a cytotoxic effect the ratio between polychromatic and normochromatic erythrocytes was determined in the same sample and expressed in polychromatic erythrocytes per total erythrocytes. The analysis was performed with coded slides.

Evaluation criteria:

The study is considered valid as the following criteria are met:
- the concurrent negative control is considered acceptable for addition to the laboratory historical control database (should ideally be within the 95% control limits of the distribution of the historical negative control database)
- at least 5 animals per group could be evaluated.
- the appropriate number of doses and cells were analysed.
- PCE to erythrocyte ratio is not less than 20% of the negative control.
- The positive control shows a statistically significant increase of micronucleated PCEs compared to the negative control and is compatible to those in the historical positive control database.

Statistics:

Statistical significance at the five per cent level (p < 0.05) was evaluated by means of the non-parametric Mann-Whitney test using the validated statistical program RScript Wilcoxon_2.Rnw.
The Holm-Bonferroni Adjustment method was used to correct for the Familiywise error rate of multiple comparisons.

Results and discussion

Test results

Key result

Sex:

female

Genotoxicity:

negative

Toxicity:

yes

Remarks:

clinical The observed systemic toxicity at the tested doses is indicative for a systemic distribution of the test item. Thus, bioavailability of the test item under the tested conditions is assumed.

Vehicle controls validity:

valid

Negative controls validity:

valid

Positive controls validity:

valid

Applicant's summary and conclusion

Conclusions:

After treatment with the test item the number of PCEs was not substantially decreased as compared to the mean value of PCEs of the vehicle control thus indicating that Butyl carbamate did not exert any cytotoxic effects in the bone marrow. In comparison to the corresponding vehicle controls there was no biologically relevant or statistically significant enhancement increase in the frequency of the detected micronulclei at any preparation interval after administration of the test item and with any dose level used.
The concurrent positive control (40 mg/kg b.w. cyclosphosphamide administered orally) was used as positive controldid which induced a substantial increase in cells with micronuclei, demonstrating the test procedure is valid.

Executive summary:

In conclusion, it can be stated that under the experimental conditions reported, the test item Butyl carbamate did not induce micronuclei as determined by the micronucleus test with bone marrow cells of the mouse. Therefore, Butyl carbamate is considered to be non-genotoxic in this in vivo micronucleus assay.