Isobutyl acrylate

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:

16.07.2001-13.11.2001

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2001

Report date:

2001

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 474 (Mammalian Erythrocyte Micronucleus Test)

GLP compliance:

yes (incl. QA statement)

Type of assay:

micronucleus assay

Test material

Test material information

Constituent 1

Reference substance name:

Isobutyl acrylate

EC Number:

203-417-8

EC Name:

Isobutyl acrylate

Cas Number:

106-63-8

Molecular formula:

C7H12O2

IUPAC Name:

isobutyl acrylate

Specific details on test material used for the study:

- Name of test material: Isobutyl acrylate
- Lot/batch No.: S 122-01-GA

Test animals

Species:

mouse

Strain:

NMRI

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: RCC Ltd. Biotechnology and Animal Breeding Division; CH-4414 Fuellinsdorf
- Age at study initiation: 8-10 weeks
- Weight at study initiation: males: mean 44.9 g; females: mean 33.6 g
- Housing: single
- Diet: pelleted standard diet, ad libitum
- Water: Tap water ad libitum



ENVIRONMENTAL CONDITIONS
- Temperature (°C): 24 +/- 4
- Humidity (%): 30-70
- Photoperiod (hrs dark / hrs light): 12/12

Administration / exposure

Route of administration:

intraperitoneal

Vehicle:

- Vehicle/solvent used: olive oil, O1500, Sigma-Aldrich Vertriebs-GmbH
- Amount of vehicle: 10 mL/kg

Duration of treatment / exposure:

single injection; harvesting of cells 24 and 48 hours after administration of test substance

Frequency of treatment:

single treatment

Doses / concentrations

Doses / concentrations 1

Dose / conc.:

250 mg/kg bw/day (nominal)

Remarks:

males/ 24 hours harvesting

Doses / concentrations 2

Dose / conc.:

500 mg/kg bw/day (nominal)

Remarks:

males/ 24 hours harvesting

Doses / concentrations 3

Dose / conc.:

1 000 mg/kg bw/day (nominal)

Remarks:

males/ 24 hours harvesting

Doses / concentrations 4

Dose / conc.:

1 000 mg/kg bw/day (nominal)

Remarks:

males/ 48 hours harvesting

Doses / concentrations 5

Dose / conc.:

312.5 mg/kg bw/day (nominal)

Remarks:

female/ 24 hours harvesting

Doses / concentrations 6

Dose / conc.:

625 mg/kg bw/day (nominal)

Remarks:

female/ 24 hours harvesting

Doses / concentrations 7

Dose / conc.:

1 250 mg/kg bw/day (nominal)

Remarks:

female/ 24 hours harvesting

Doses / concentrations 8

Dose / conc.:

1 250 mg/kg bw/day (nominal)

Remarks:

female/ 48 hours harvesting

No. of animals per sex per dose:

5

Control animals:

yes, concurrent vehicle

yes, historical

Positive control(s):

cyclophosphamide, 40 mg/kg bw, i.p.

Examinations

Tissues and cell types examined:

bone marrow

Details of tissue and slide preparation:

CRITERIA FOR DOSE SELECTION:
Dose selection: on basis of the results from a pre-experiment.

TREATMENT:
10 animals per group were evaluated for micronuclei. At least 2000 polychromatic erythrocytes (PCE) per animal were scored. Cytotoxicity was evaluated by the ratio of polychromatic to normochromatic erythrocytes (determined in the same samples as used for micronuclei scoring).

Evaluation criteria:

A test substance is classified as mutagenic if it induces either a dose-related increase in the number of micronucleated polychromatic erythrocytes, which clearly exceeds the negative control range or a relevant positive response for at least one of the test points.
Statistical methods (nonparametric Mann-Whitney test) can be used as an aid in evaluating the results. However, the primary point of consideration is the biological relevance of the results.
A test substance producing neither a dose-related increase in the number of micronucleated polychromatic erythrocytes nor a positive response at any of the test points is considered non-mutagenic in this system.

Statistics:

A non-parametric Mann-Whitney-Test was performed.

Results and discussion

Test results

Key result

Sex:

male/female

Genotoxicity:

negative

Toxicity:

yes

Remarks:

Clinical signs in the high dose animals

Vehicle controls validity:

valid

Negative controls validity:

not examined

Positive controls validity:

valid

Additional information on results:

RESULTS OF RANGE-FINDING STUDY
- Dose range: male: 0, 1250 mg/kg bw; female: 0, 1500 mg/kg bw
- Clinical signs of toxicity in test animals: In the dose range-finder pre-experiment, 1250 mg/kg bw i.p. were lethal to both tested male animals. In females, 1500 mg/kg bw i.p. were lethal for 1 of 2 animals.

RESULTS OF DEFINITIVE STUDY
The test item did not induce micronuclei at any dose level or any harvesting time used in this study. It was considered non-clastogenic and non-aneugenic in this assay.
The mean number of normochromatic erythrocytes was not increased after treatment with the test substance as compared to the controls, indicating that the test item had no cytotoxic effect on the bone marrow. The positive control substance induced a distinct increase of micronuclei.
- Clinical signs of toxicity in test animals: males at 1000 mg/kg bw: reduced spontaneous activity, eyelid closure, apathy, prostrate position. females at 1250 mg/kg bw: reduced spontaneous activity, eyelid closure, apathy, prostrate position. 1000 mg/kg bw induced clear signs of toxicity in 7 male animals (reduced activity, eyelid closure, apathy, prostrate position). In females, at 1250 mg/kg bw clear signs of toxicity were observed in 7 female animals (reduced activity, eyelid closure, apathy, prostrate position).

Any other information on results incl. tables

Summary of Micronucleus Test Results

Males

Test group	dose (mg/kg bw)	sampling time (h)	PCEs with micronuclei (‰)	range	PCE / NCE
vehicle	0	24	1.20	2 - 3	2000 / 1965
test substance	250	24	0.60	0 - 3	2000 / 1888
test substance	500	24	0.60	0 - 3	2000 / 2141
test substance	1000	24	1.20	1 - 4	2000 / 2371
positive control	40	24	14.90	17 - 36	2000 / 1771
vehicle	0	48	0.00	0 - 0	2000 / 2022
test substance	1000	48	0.40	0 - 2	2000 / 2642

Females:

Test group	dose (mg/kg bw)	sampling time (h)	PCEs with micronuclei (‰)	range	PCE / NCE
vehicle	0	24	0.10	0 - 1	2000 / 1965
test substance	312.5	24	0.50	0 - 3	2000 / 1888
test substance	625	24	0.40	0 - 3	2000 / 2141
test substance	1250	24	0.20	0 - 2	2000 / 2371
positive control	40	24	12.10	11 - 43	2000 / 1771
vehicle	0	48	0.00	0 - 0	2000 / 2022
test substance	1250	48	0.10	0 - 21	2000 / 2642