Maleic anhydride

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:

weight of evidence

Study period:

1983-03-14 to 1983-06-02

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

comparable to guideline study with acceptable restrictions

Data source

Reference

Reference 1

Reference Type:

study report

Title:

Unnamed

Year:

1983

Report date:

1983

Reference 2

Reference Type:

review article or handbook

Title:

Maleic Anhydride and Maleic Acid, SIDS Initial Assessment Report For SIAM 18

Author:

OECD SIDS

Year:

2004

Bibliographic source:

OECD SIDS Initial Assessment Report For SIAM 18, Paris, France, 20-23 April 2004

Materials and methods

Test guideline

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 475 (Mammalian Bone Marrow Chromosome Aberration Test)

Deviations:

yes

Remarks:

(positive controls were not used, only 50 cells per animal were analyzed)

GLP compliance:

no

Type of assay:

chromosome aberration assay

Test material

Test material information

Constituent 1

Reference substance name:

Maleic anhydride

EC Number:

203-571-6

EC Name:

Maleic anhydride

Cas Number:

108-31-6

Molecular formula:

C4H2O3

IUPAC Name:

2,5-dihydrofuran-2,5-dione

Details on test material:

- Name of test material (as cited in study report): Maleic anhydride
- Physical state: crystalline briquettes
- Analytical purity: 100% active ingredient was assumed
- Stability under test conditions: Under the conditions of the assay, the compound was assumed to be stable.
- Storage condition of test material: room temperature

Test animals

Species:

rat

Strain:

Sprague-Dawley

Remarks:

albino

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Charles River
- Housing: individually
- Diet: ad libitum (except during the exposure period)
- Water: ad libitum (except during the exposure period)
- Acclimation period: 19 days


ENVIRONMENTAL CONDITIONS
- Temperature (°C): 21-27
- Humidity (%): 32-66
- Photoperiod (hrs dark / hrs light): 12/12

Administration / exposure

Route of administration:

inhalation

Vehicle:

- Vehicle(s)/solvent(s) used: none

Details on exposure:

GENERATION OF TEST ATMOSPHERE / CHAMBER DESCRIPTION
- Exposure apparatus: Atmospheres were generated by heating maleic anhydride in flasks and transporting the vapors with nitrogen gas to 5 m³ glass and stainless steel chambers.
- Temperature, humidity in air chamber: 23-25°C, 36-45%
- Air flow rate: 1 L/min


TEST ATMOSPHERE
- Brief description of analytical method used: Atmospheric concentrations were monitored five times during the exposure period with two methods: 1. chamber samples were bubbled through distilled water and maleic acid was determined by a HPLC method; 2. chamber samples were drawn through a glass tube filled with p-Anisidine coated with XAD-resin beads, and the maleic anhydride derivative was determined by HPLC (methods provide a measure of total maleic (maleic acid plus maleic anhydride converted to maleic acid) and maleic anhydride).
- Samples taken from breathing zone: yes (5 times in 6 hours)

Duration of treatment / exposure:

6 hrs

Frequency of treatment:

once

Post exposure period:

Sacrifice at 6, 24, and 48 hours.

Doses / concentrations

Doses / concentrations 1

Dose / conc.:

0 mg/m³ air (nominal)

Doses / concentrations 2

Dose / conc.:

1 mg/m³ air (nominal)

Remarks:

analytical concentration range: 1.66 - 3.06 mg/m³; average concentration of 2.34 mg/m³.

Doses / concentrations 3

Dose / conc.:

100 mg/m³ air (nominal)

Remarks:

analytical concentration range: 20.43 - 49.29 mg/m³; average concentration of 33.30 mg/m³.

No. of animals per sex per dose:

15

Control animals:

yes, concurrent no treatment

Positive control(s):

none

Examinations

Tissues and cell types examined:

Bone marrow cells were collected and processed for analysis.

Details of tissue and slide preparation:

SAMPLING TIMES: Five animals per sex per group were killed 6, 24 or 48 hours following termination of exposure.


DETAILS OF SLIDE PREPARATION: Bone marrow cells were removed by aspiration from both femurs of rat immediately after sacrifice. Subsequently, the cells were fixed, dropped on slides and stained. Two slides were prepared for each animal and analyzed by an individual who was unfamiliar with the animals identity. Generally, fifty cells in metaphase were examined from each rat that provided analyzable cells.


METHOD OF ANALYSIS: The following parameters were calculated for each animal: numbers and type of chromosomal aberrations, mitotic index, chromosome number, and vernier location each metaphase containing damage .

Statistics:

The mean mitotic indices, mean modal numbers, percent aberrant cells and the total number of aberrations per animal for each group were statistically compared using the Kruskal-Wallis nonparametric analysis of variance and nonparametric all pairwise group comparison.

Results and discussion

Test results

Sex:

male/female

Genotoxicity:

negative

Toxicity:

no effects

Negative controls validity:

valid

Positive controls validity:

not examined

Additional information on results:

No deaths occurred during the study but all treated animals were sluggish during exposure and many of the high-dose group had squinted eyes and bloody encrusted nose. One hour after exposure, all rats in the high dose group appeared sluggish and there was a bloody crust around the nose of four males and six females. No evidence of toxicity in the bone marrow cells were observed. There were no treatment-related effects on the frequency of chromosomal aberrations at any of the times examined. A statistically significant increase (p=0.022) in chromosome number was observed in the low-dose animals at 6 hours and in the high-dose animals at 24 hours (p=0.045); these were not considered treatment-related. None of the rats had polyploid or aneuploid cells and none had consistently abnormal chromosome numbers.

Applicant's summary and conclusion

Conclusions:

In this study, under the given conditions, maleic anhydride is not considered to be clastogenic at any of the dose levels tested.

Executive summary:

In a Sprague-Dawley albino rats bone marrow chromosomal aberration assay (equivalent to OECD Guideline 475), 15 rats/sex/concentration were treated via inhalation route with maleic anhydride (100 % purity). at concentrations of 0, 1 or 100 mg/m³. Bone marrow cells were harvested at 6, 24- and 48-hours post-treatment.

There were signs of toxicity during the study. All treated animals were sluggish during exposure and many of the high-dose group had squinted eyes and bloody encrusted nose. One hour after exposure, all rats in the high dose group appeared sluggish and there was a bloody crust around the nose of four males and six females. However, no evidence of toxicity in the bone marrow cells were observed. There were no treatment-related effects on the frequency of chromosomal aberrations at any of the times examined. A statistically significant increase (p=0.022) in chromosome number was observed in the low-dose animals at 6 hours and in the high-dose animals at 24 hours (p=0.045); these were not considered treatment-related. None of the rats had polyploid or aneuploid cells and none had consistently abnormal chromosome numbers.

This study is classified as acceptable with some restrictions ( purity of the test substance was not known and positive controls were not used) and satisfies the requirement for Test Guideline OECD 475 for in vivo cytogenetic mutagenicity data.