Registration Dossier

Administrative data

Endpoint:
in vivo mammalian somatic cell study: cytogenicity / bone marrow chromosome aberration
Remarks:
Type of genotoxicity: chromosome aberration
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Comparable to guideline study with acceptable restrictions.

Data source

Referenceopen allclose all

Reference Type:
secondary source
Title:
Unnamed
Year:
1983
Reference Type:
publication
Title:
Unnamed
Year:
1983
Report Date:
1983
Reference Type:
secondary source
Title:
In vivo Bone Marrow Chromosome Study in Rats (Inhalation exposure)
Author:
Farrow M.G., and Cortina, T.
Year:
1983
Bibliographic source:
cited in: EPA, Health and Environmental effects profile for maleic anhydride, 06/1986

Materials and methods

Test guideline
Qualifier:
equivalent or similar to
Guideline:
OECD Guideline 475 (Mammalian Bone Marrow Chromosome Aberration Test)
Deviations:
yes
Remarks:
(purity of the test substance was not known, positive controls were not used, only 50 cells per animal were analyzed)
GLP compliance:
no
Type of assay:
chromosome aberration assay

Test material

Reference
Name:
Unnamed
Type:
Constituent
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:
other: Sprague-Dawley albino rats
Sex:
male/female
Details on test animals 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 (%): 36-45
- Photoperiod (hrs dark / hrs light): 12/12


Administration / exposure

Route of administration:
inhalation
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 / concentrationsopen allclose all
Remarks:
Doses / Concentrations:
0, 1, and 100 mg/m³ (0, 0.25, and 25 ppm)
Basis:
other: target concentration
Remarks:
Doses / Concentrations:
0, 9.7, 140 mg/m³
Basis:
nominal conc.
Remarks:
Doses / Concentrations:
0, 2.3, 33 mg/m³
Basis:
analytical conc.
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 valid:
yes
Positive controls valid:
not examined

Any other information on results incl. tables

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:
Interpretation of results (migrated information): negative
Under the conditions of this study, Maleic Anhydride is not considered to be clastogenic at any of the levels tested.