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Toxicological information

Genetic toxicity: in vivo

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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:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: see 'Remark'
Remarks:
Conducted in compliance with OECD Principles of Good Laboratory Practice (GLP), United States Food and Drug Administration GLP Regulations, United States Environmental Protection Agency GLP Standards, the United Kingdom GLP Compliance Programme, and the Japanese GLP Standard.

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
1999
Report Date:
1999

Materials and methods

Test guideline
Qualifier:
no guideline followed
Principles of method if other than guideline:
Male and female ICR mice were dosed by oral gavage with 0, 500, 1000, or 2000 mg/kg Bisphenol A. Bone marrow cells were collected at 24 or 48 hours after treatment and were examined microscopically for the presence of micronucleated polychromatic erythrocytes.
GLP compliance:
yes
Type of assay:
micronucleus assay

Test material

Reference
Name:
Unnamed
Type:
Constituent
Test material form:
solid: granular
Details on test material:
- opaque, white, granular solid
- purity: 99.1 % (according to accompanying documentation)

Test animals

Species:
mouse
Strain:
ICR
Sex:
male/female
Details on test animals and environmental conditions:
TEST ANIMALS
- Source: Harlan Sprague Dawley, Inc. (Frederick, Maryland, United States)
- Age at study initiation: 6 to 8 weeks
- Weight at study initiation: males, 28.9 - 35.5 g; females, 26.2 - 32.2 g
- Assigned to test groups randomly: no, distributed according to body weight
- Fasting period before study: no
- Housing: Mice of the same sex were housed up to five per cage in plastic autoclavable cages maintained on stainless steel racks. Heat-treated hardwood chips were used for bedding.
- Diet: ad libitum, certified laboratory rodent chow (Harlan TEKLAD certified Rodent 7012C) which had been analyzed for environmental contaminants
- Water: ad libitum, tap water
- Acclimation period: At least 5 days


ENVIRONMENTAL CONDITIONS
- Temperature (°C): 68-80
- Humidity (%): 30-70
- Photoperiod: 12 hours light/12 hours dark

Administration / exposure

Route of administration:
oral: gavage
Vehicle:
Corn oil
Details on exposure:
Mice were assigned to seven experimental groups of five males and five females each according to a computer-generated program which is based on distribution according to body weight. The BPA-vehicle mixture, vehicle alone, or positive control were administered by oral gavage at a constant volume of 20 mL/kg body weight. All mice were weighed immediately prior to dose administration and the dose volume was based on individual body weights.
Duration of treatment / exposure:
Single administration by oral gavage
Frequency of treatment:
Single adminstration
Post exposure period:
24 or 48 hours
Doses / concentrations
Remarks:
Doses / Concentrations:
0, 500, 1000, or 2000 mg/kg
Basis:
nominal conc.
No. of animals per sex per dose:
10 for vehicle controls and highest test dose (2000 mg/kg); 5 for the low and mid test doses (500 and 1000 mg/kg) and the positive controls
Control animals:
yes, concurrent vehicle
Positive control(s):
Cyclophosphamide at 50 mg/kg

Examinations

Tissues and cell types examined:
Bone marrow erythrocytes
Details of tissue and slide preparation:
Bone marrow cells were isolated from femurs and suspensions of cells were spread on glass slides. Two slides were prepared from each mouse. Slides were fixed in methanol, stained with May-Gruenwald-Giemsa, and permanently mounted.
Evaluation criteria:
2000 polychromatic erythrocytes per slide were scored for the presence of micronuclei. The number of micronucleated normochromatic erythrocytes in the field of 2000 polychromatic erythrocytes was enumerated and the proportion of polychromatic to total erythrocytes was recorded per 1000 erythrocytes.

A positive response was induced if a dose-responsive increase in micronucleated polychromatic erythrocytes was observed and one or more doses were statistically elevated relative to the vehicle control at any sampling time. If a single treament group was significantly elevated at one sacrifice time with no evidence of a dose-response, the assay was considered suspect of unconfirmed positive and a repeat assay recommended. A negative response was determined if no statistically significant increase in micronucleated polychromatic erythrocytes above the concurrent vehicle control was observed at any sampling time.

The criteria for a valid test were described as follows: The mean incidence of micronucleated polychromatic erythrocytes must not exceed 5/1000 polychromatic erythrocytes (0.5%) in the vehicle control group. The incidence in the positive control group must be significantly increased relative to the vehicle control group.
Statistics:
The incidence of micronucleated polychromatic erythrocytes was determined for each mouse and treatment group. Statistical significance was determined using the Kastenbaum-Bowman tables which are based on the binomial distrubution.

Results and discussion

Test results
Sex:
male/female
Genotoxicity:
negative
Toxicity:
yes
Vehicle controls validity:
valid
Negative controls validity:
not examined
Positive controls validity:
valid
Additional information on results:
No mortality occurred at any dose level during the course of the study. Lethargy was noted in 2 of 5 male mice and 1 of 5 female mice at 500 mg/kg and in all mice at 1000 and 2000 mg/kg. Piloerection was observed in all mice at 1000 and 2000 mg/kg.

Reductions of 15 to 24% in the ratio of polychromatic erythrocytes to total erythrocytes were observed in male and female dose groups 24 hours after treatment with all doses of BPA. Reductions of 26% and 36% were observed in male and female mice, respectively, 48 hours after treatment with 2000 mg/kg BPA.

The number of micronucleated polychromatic erythrocytes per 2000 polychromatic erythrocytes in BPA-treated groups was not increased relative to their respective vehicle controls in either males or females, regardless of dose level or bone marrow collection time (p>0.05).

Applicant's summary and conclusion

Conclusions:
Interpretation of results (migrated information): negative
The authors concluded that under the conditions of the assay, BPA was negative in the micronucleus test using male and female ICR mice.
Executive summary:

Male and female ICR mice were dosed by oral gavage with 0, 500, 1000, or 2000 mg/kg BPA. Bone marrow cells were collected at 24 or 48 hours after treatment and were examined microscopically for the presence of micronucleated polychromatic erythrocytes. No mortality occurred at any dose level during the course of the study. Lethargy was noted in 2 of 5 male mice and 1 of 5 female mice at 500 mg/kg and in all mice at 1000 and 2000 mg/kg. Piloerection was observed in all mice at 1000 and 2000 mg/kg. Reductions of 15 to 24% in the ratio of polychromatic erythrocytes to total erythrocytes were observed in male and female dose groups 24 hours after treatment with all doses of BPA. Reductions of 26% and 36% were observed in male and female mice, respectively, 48 hours after treatment with 2000 mg/kg BPA. The number of micronucleated polychromatic erythrocytes per 2000 polychromatic erythrocytes in BPA-treated groups was not increased reltive to their respective vehicle controls in either males or females, regardless of dose level or bone marrow collection time (p>0.05).