Registration Dossier

Administrative data

Endpoint:
in vivo mammalian somatic cell study: cytogenicity / erythrocyte micronucleus
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: well documented GLP study

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
1991
Report Date:
1991

Materials and methods

Test guideline
Qualifier:
according to
Guideline:
EPA OTS 798.5395 (In Vivo Mammalian Cytogenics Tests: Erythrocyte Micronucleus Assay)
GLP compliance:
yes (incl. certificate)
Remarks:
testing lab.
Type of assay:
micronucleus assay

Test material

Reference
Name:
Unnamed
Type:
Constituent
Details on test material:
- Name of the test substance used in the study report: 4-Hydroxyacetophenone (4-HAP) Commercial (C1650)
- purity: > 99%
- Lot/batch No.: FHBB049

Test animals

Species:
mouse
Strain:
ICR
Sex:
male/female
Details on test animals and environmental conditions:
At the initiation of the study, the mice were 6-8 weeks old. Animal body weights were recorded.
Animals were obtained from a source monitored for evidence of parasites, pathogenic respiratory and enteric bacteria, Mycoplasmias, and appropriate murine viruses and were quarantined for no less than 5 days after receipt on 8-13-91 for the pilot study, 8-6-91 for the repeat pilot study, 9-3-91 for the toxicity study and on 10-8-91 for the micronucleus test. Mice for the initial pilot study were received from Altamont, NY instead of Frederick, MD due to availability from the supplier. Mice for the repeat pilot study were 6-9 weeks of age due to availibility of animals in house. These deviations from protocol were documented in the raw data with deviation reports und were concluded by the study director to have no effect on the quality of the study. The mice were observed each working day for signs of illness, unusual food and water consumption, and other conditions of poor health. The animals were judged to be healthy prior to utilization in the assay.
The animals were housed in a facility with a controlled environment of 74±6°F, 50±20% relative humidity, and a 12 hour light/dark cycle.
Mice were group housed up to five per cage in plastic autoclavable cages with filter tops. Hardwood chips were used for bedding. Animals had free access to certified laboratory rodent chow which had been analyzed for environmental contaminants and to tap water.

Administration / exposure

Route of administration:
intraperitoneal
Vehicle:
corn oil
Duration of treatment / exposure:
single treatment
Frequency of treatment:
once
Post exposure period:
single treatment
Doses / concentrations
Remarks:
Doses / Concentrations:
113, 225, 450 mg/kg
Basis:

No. of animals per sex per dose:
5
Control animals:
yes
Positive control(s):
cyclophosphamide

Examinations

Tissues and cell types examined:
bone marrow
Details of tissue and slide preparation:
Before the start of the mutagenicity assay, a pilot study and a range-finding study were performed. In the pilot study one group of each five ICR mice of either sex and four groups of two males each were used. The test substance was administered by ip injection to male and female mice at 2500 mg/kg bw and to male mice at 1, 10, 100 and 1000 mg/kg bw (at a volume of 10 ml test substance vehicle (1% CMC) mixture/kg bw). A repeat pilot study was done with a single dose level of 5000 mg/kg bw given to each 5 male and female mice. Within six days mortality occured in all animals of the 5000 mg/kg group in each two male and female animals of the 2500 mg/kg group and in 2/2 males at 1000 mg/kg bw. Clinically the following signs were noted within 3 hours or later after test substance administration: lethargy, ataxia tremors, convulsions and irregular breathing at 2500 mg/kg, prostration, tremors, lethargy, convulsions and irregular breathing at 5000 mg/kg. All other animals appeared normal throughout the observation period.
Since there were difficulties in maintaining a homogenous suspension of the test substance in CMC, the vehicle was changed to corn oil for the range-finding and the micronucleus assay.
In the range finding test the test substance was administered by ip injections to each 5 male and female mice at dose levels of 391, 625, 1000 and 1600 mg/kg bw. A vehicle control run in parallel. Mortality occurred within 2 days of dose administration in all animals at 1000 and 1600 mg/kg be and in all males and 4/5 females at 625 mg/kg bw. Clinically (signs noted within several hours of dose administration or later) rough hair coat at 391 mg/kg, and prostration, tremors and irregular breathing at 625 and 1000 mg/kg bw. All other surviving animals appeared normal throughout the observation period. The LD50 was calculated to be approx. 574 mg/kg after a 7 day observation period. The high dose for the micronucleus assay was set at 450 mg/kg bw (estimating to be approx. 80% of the LD50 after a 7 day observation period).
Evaluation criteria:
The mean incidence of micronucleated polychromatic erythrocytes must not exceed 5/1000 polychromatic erythrocytes (0.5%) in the negative (vehicle) control. The incidence of micronucleated polychromatic erytrocytes in the positive control group must be significantly increased relative to the negative control.
Statistics:
yes

Results and discussion

Test results
Sex:
male/female
Genotoxicity:
negative
Toxicity:
no effects
Vehicle controls validity:
valid
Negative controls validity:
valid
Positive controls validity:
valid
Additional information on results:
Clinical signs which occurred on the days following dose administration included: lethargy, rough hair coat and hunched posture. One male of the high dose was found dead on the third day following treatment and was replaced at the time of bone marrow collection with an animal from the replacement group that was also dosed with 450 mg/kg bw. With respect to the incidence of micronucleated polychromatic erythrocytes, no change in the ratio of polychromatic erythrocytes to total erythrocytes was apparent in test substance-treated animals when compared to vehicle control-treated animals. No significant increase of micronucleated polychromatic erythrocytes/1000 polychromatic erythrocytes was noted in males and females, regardless of dose level or bone marrow collection time.

Applicant's summary and conclusion

Conclusions:
Interpretation of results (migrated information): negative