Acetophenone

Genetic toxicity: in vitro

Administrative data

Endpoint:

in vitro cytogenicity / chromosome aberration study in mammalian cells

Type of information:

experimental study

Adequacy of study:

key study

Study period:

from 04-AUG-2006 to 25-MAY-2007

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2007

Report date:

2007

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 473 (In Vitro Mammalian Chromosomal Aberration Test)

GLP compliance:

yes (incl. QA statement)

Type of assay:

in vitro mammalian chromosome aberration test

Test material

Test material information

Constituent 1

Reference substance name:

Acetophenone

EC Number:

202-708-7

EC Name:

Acetophenone

Cas Number:

98-86-2

Molecular formula:

C8H8O

IUPAC Name:

1-phenylethanone

Details on test material:

- Name of test material (as cited in study report): acetophenone
- Physical state: liquid
- Analytical purity: 99.36 %
- Purity test date: 2006-06-21
- Lot/batch No.: E38/06

Method

Species / strain

Species / strain / cell type:

Chinese hamster lung fibroblasts (V79)

Metabolic activation:

with and without

Metabolic activation system:

phenobarbital/ß-naphthoflavone induced rat liver S9

Test concentrations with justification for top dose:

- S9: 32.3 - 517.5 µg/mL
+ S9: 64.7 - 1100 µg/ml

Vehicle / solvent:

- Vehicle(s)/solvent(s) used: ethanol
- Justification for choice of solvent/vehicle: solubility

Controls

Untreated negative controls:

no

Negative solvent / vehicle controls:

yes

Positive controls:

yes

Positive control substance:

other: without S9: ethylmethane sulfonate; with S9: cyclophosphamide

Details on test system and experimental conditions:

METHOD OF APPLICATION: in medium

DURATION
- Exposure duration: without S9: 4, 18, 28 hrs; with S9: 4 hrs
- Fixation time (start of exposure up to fixation or harvest of cells): 18 or 28 hrs

SPINDLE INHIBITOR (cytogenetic assays): colcemid
STAIN (for cytogenetic assays): Giemsa

NUMBER OF REPLICATIONS: duplicates, verification by repeat assays

NUMBER OF CELLS EVALUATED: 200 metaphases per test concentration

DETERMINATION OF CYTOTOXICITY
- Method: mitotic index

OTHER EXAMINATIONS:
- Determination of polyploidy: yes

Evaluation criteria:

Clastogenicity: positive test result if structural chromosome aberrations excluding gaps are higher than the range of the historical control of 0.0 - 4.0 %, and either a concentration related or significant increase (p<0.05) of structural chromosome aberrations is observed
Aneugenicity: positive test result if numerical chromosome aberrations are higher than the range of the historical control of 0.0 - 5.6 %

Statistics:

Fisher's exact est

Results and discussion

Test results

Test results 1

Species / strain:

Chinese hamster lung fibroblasts (V79)

Metabolic activation:

with

Genotoxicity:

positive

Remarks:

induction of structural chromosomal aberrations

Cytotoxicity / choice of top concentrations:

cytotoxicity

Vehicle controls validity:

valid

Positive controls validity:

valid

Test results 2

Species / strain:

Chinese hamster lung fibroblasts (V79)

Metabolic activation:

without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

cytotoxicity

Vehicle controls validity:

valid

Positive controls validity:

valid

Additional information on results:

TEST-SPECIFIC CONFOUNDING FACTORS
- Effects of pH: not affected
- Effects of osmolality: not affected
- Precipitation: at >= 513 µg/mL both without and with S9

RANGE-FINDING/SCREENING STUDIES:
no cytotoxicity up to 1035 µg/mL after 4 hr treatment; clear cytotoxicity at >= 517.5 µg/mL after 24 hr treatment

COMPARISON WITH HISTORICAL CONTROL DATA:
without S9: Experiment IA: single signifcant increase of aberrant cells after 4 hr-treatment and 18 hr-preparation interval at 32.2 µg/mL, however, the aberration rate of 2.0 % was clearly within the historical control range; therefore regarded to be of no biological relevance
with S9: increases of aberrant cells exceeding the laboratory's control range were observed in experiment IA, IIA and IIB (see Table)

RANGE-FINDING/SCREENING STUDIES:
precipitation of test substance at >= 513 µg/mL both without and with S9; no cytotoxicity up to 1035 µg/mL after 4 hr treatment; clear cytotoxicity at >= 517.5 µg/mL after 24 hr treatment

COMPARISON WITH HISTORICAL CONTROL DATA:
without S9: single signifcant increase after 4 hr-treatment and 18 hr-preparation interval at 32.2 µg/mL, however, the aberration rate of 2.0 % was clearly within the historical control range; therefore regarded to be of no biological significance

ADDITIONAL INFORMATION ON CYTOTOXICITY:
without S9 after 4 hr treatment at 129.4 µg/mL, after 18 hr treatment at 517.5 µg/mL, after 28 hr treatment at 258.8 µg/mL; with S9 after 4 hr treatment at >= 900 µg/mL

Any other information on results incl. tables

Table: Significant changes of structural chromosomal aberrations after treatment with acetophenone in the presence of metabolic activation

Experiment	Test concentration (µg/mL)	% aberrant cells excluding gaps	Significance level p-value	% aberrant cells with exchanges
Experiment IA	Solvent control	1.5	-	1.0
	64.7	4.0	0.070	1.5
	129.4	5.0 *	0.027	1.5
	258.8	4.5 *	0.044	0.5
Experiment IB (Repeat)	Solvent control	2.5	-	1.0
	100.0	3.0	0.386	0.5
	200.0	3.0	0.386	0.0
	300.0	3.5	0.288	0.5
Experiment IIA	Solvent control	1.5	-	1.0
	258.8	3.0	0.169	0.0
	517.5	2.5	0.252	0.0
	1035.0	9.5 *	< 0.001	9.5 ^§
Experiment IIB (Repeat)	Solvent control	0.5	-	0.0
	900	10.0 *	< 0.001	5.5 ^§
	1000	38.0 *	< 0.001	14.0 ^§
	1100	20.0 *	< 0.001	7.5 ^§

* effect of statistical significance and exceeding the historical control range

^§ effect exceeding the historical control range

As the significant effect of experiment IA was not repeatable in experiment IB , it was regarded as biologically not relevant.

The significant increase of structural aberrations in experiment IIA at 1035 µg/mL was confirmed at doses of 900 to 1100 µg/mL in experiment IIB. Distinct increases in the number of cells with exchanges provided additional evidence for a clastogenic potential.

Applicant's summary and conclusion

Conclusions:

Interpretation of results (migrated information):
negative without metabolic activation
positive with metabolic activation

A clastogenic potential of acetophenone is indicated in the presence of metabolic activation by S9 mix by the induction of structural chromosomal aberrations which is confirmed by increased frequencies of exchanges.

Executive summary:

In a chromosomal aberration test with V79 cells according to OECD Guideline 473, a clastogenic potential of acetophenone is indicated in the presence of metabolic activation by S9 mix by the repeatable induction of structural chromosomal aberrations (test concentrations of 900 µg/mL and higher), which is confirmed by increased frequencies of exchanges. There was no biologically relevant increase of structural aberrations in the absence of metabolic activation nor were there any increased frequencies of polyploid cells.