1-(2,4-dichlorophenyl)ethan-1-one

Genetic toxicity: in vitro

Administrative data

Endpoint:

in vitro gene mutation study in bacteria

Type of information:

experimental study

Adequacy of study:

key study

Study period:

18 May 1994 - 24 June 1994

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study with acceptable restrictions

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

1994

Report date:

1994

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 471 (Bacterial Reverse Mutation Assay)

Deviations:

yes

Remarks:

Only 4 strains tested

GLP compliance:

yes

Type of assay:

bacterial reverse mutation assay

Test material

Test material information

Constituent 1

Reference substance name:

1-(2,4-dichlorophenyl)ethan-1-one

EC Number:

218-780-8

EC Name:

1-(2,4-dichlorophenyl)ethan-1-one

Cas Number:

2234-16-4

Molecular formula:

C8H6Cl2O

IUPAC Name:

1-(2,4-dichlorophenyl)ethan-1-one

Test material form:

solid: crystalline

Method

Species / strain

Species / strain / cell type:

S. typhimurium TA 1535, TA 1537, TA 98 and TA 100

Metabolic activation:

with and without

Metabolic activation system:

S9 mix

Vehicle / solvent:

- Vehicle(s)/solvent(s) used: DMSO.

Controls

Untreated negative controls:

yes

Negative solvent / vehicle controls:

yes

Positive controls:

yes

Positive control substance:

9-aminoacridine

2-nitrofluorene

sodium azide

other: 2-aminoanthracene: +S9 (all strains)

Details on test system and experimental conditions:

METHOD OF APPLICATION: in agar (plate incorporation)
Top agar was prepared for the Salmonella strains by mixing 100 mL agar with 10 mL of a 0.5 mM histidine-biotin solution. The following ingredients were added (in order) to 2 mL molten top agar at approx. 45 ºC: 0.1 mL of an overnight nutrient broth culture of the bacterial tester strain, 0.1 mL test compound solution and 0.5 mL S9 mix (if required) or buffer. After mixing, the liquied was poured into a pretidish with minimal agar. After incubation for approximately 48 hours at approx. 37 ºC in the dark, colonies (his+ revertants) were counted. Two independent studies were performed.

DURATION
- Expression time (cells in growth medium): 48 hours

SELECTION AGENT (mutation assays): histidine

NUMBER OF REPLICATIONS: 3

DETERMINATION OF CYTOTOXICITY
- Method: Reduced rate of spontaneously occuring colonies and the visible thinning of the bacterial lawn (evaluated microscopically).

Evaluation criteria:

A test article is classified mutagenic if either of the following conditions under a) and b) is achieved:
a) a test article produces at least a 2-fold increase in the mean number of revertants per plate of at least one of the tester strains over the man number of revertants per plate of the appropriate vehicle control at complete bacterial background lawn.
b) a test article induces a dose-related increase in the mean number of revertants per plate of at least one of the tester strains over the mean number of revertants per plate of the appropriate vehicle control in at least two to three concentrations of the test article at complete bacterial background lawn.

Results and discussion

Test results

Key result

Species / strain:

S. typhimurium, other: TA100, TA1535, TA1537, TA98

Metabolic activation:

with and without

Genotoxicity:

positive

Remarks:

TA100 (+S9), TA98 (+S9)

Cytotoxicity / choice of top concentrations:

cytotoxicity

Remarks:

2500 and 5000 µg/plate (+/-S9)

Vehicle controls validity:

valid

Untreated negative controls validity:

valid

Positive controls validity:

valid

Additional information on results:

In the absence of the metabolic activation system the test compound did not induce a dose dependent increase in the number of revertant colonies with any of the tester strains. In the presence of metabolic activation, the test compound resulted in relevant increases in the number of revertant colonies with the Salmonella strains TA98 and TA100. The substance was concluded to be mutagenic in these bacterial test systems in the presence of an exogenous metabolizing system.

TEST-SPECIFIC CONFOUNDING FACTORS
- Precipitation: No precipitation was observed up to the highest investigated dose of 5000 µg/plate.

RANGE-FINDING/SCREENING STUDIES:

HISTORICAL CONTROL DATA (with ranges, means and standard deviation and confidence interval (e.g. 95%)
- Positive historical control data:
- Negative (solvent/vehicle) historical control data:

ADDITIONAL INFORMATION ON CYTOTOXICITY:
- Measurement of cytotoxicity used: The test compound was tested at doses of 4 to 5000 µg/plate and proved to be toxic to most of the bacterial strains at a dose of 2500 µg/plate and above. Thinning of the bacterial lawn and a reduction in the number of colonies were observed at this dose. In the cytotoxic experimient with the dilution of Salmonell strain TA100 the test compound proved to be toxic at a dose of 500 µg/plate in the absence and 1000 µg/plte in the presence of a metabolic activation system and above.

Any other information on results incl. tables

First experiment: 

 

Strain	+S9/-S9	Dose (µg/plate)	Mean (3)	SD	Ratio	Bacterial lawn
TA100	+S9	0	138.3	18.9
		4	141.7	14.0	1.0
		20	356.7	16.0	1.1
		100	200.3	11.1	1.4
		500	489.7	68.3	3.5
		2500	115.7	11.5	0.8	None
		5000	1.0	0.0	0.0	None
TA100	-S9	0	121.0	12.5
		4	118.7	8.1	1.0
		20	113.0	5.3	0.9
		100	129.0	7.0	1.1
		500	124.7	3.2	1.0
		2500	57.7	15.5	0.5	Incomplete
		5000	0.3	0.6	0.0	None
TA1535	+S9	0	9.7	2.9
		4	12.7	1.5	1.3
		20	12.0	1.7	1.2
		100	11.7	2.1	1.2
		500	12.3	5.9	1.3
		2500	4.0	1.0	0.4	None
		5000	0.3	0.6	0.0	None
TA1535	-S9	0	7.7	0.9
		4	13.0	3.5	1.7
		20	8.3	0.6	1.1
		100	7.7	2.5	1.0
		500	9.7	3.8	1.3
		2500	0.3	0.6	0.0	None
		5000	0.0	0.0	0.0	None
TA1537	+S9	0	17.7	1.5
		4	15.3	0.6	0.9
		20	16.3	4.2	0.9
		100	20.3	1.5	1.1
		500	19.3	4.0	1.1
		2500	3.0	1.0	0.2	Incomplete
		5000	1.0	0.0	0.1	None
TA1537	-S9	0	17.7	1.2
		4	17.3	2.5	1.0
		20	22.7	0.6	1.3
		100	15.7	5.1	0.9
		500	14.7	4.0	0.8
		2500	2.7	2.1	0.2	None
		5000	0.0	0.0	0.0	None
TA98	+S9	0	29.7	11.2
		4	37.7	6.0	1.3
		20	34.0	5.2	1.1
		100	38.0	8.7	1.3
		500	5.7	3.5	1.8
		2500	2.0	1.0	0.1	Incomplete
		5000	0.0	0.0	0.0	None
TA98	-S9	0	23.3	2.3
		4	27.3	10.1	1.2
		20	29.0	4.0	1.2
		100	27.3	4.5	1.2
		500	34.0	7.5	1.5
		2500	3.3	1.5	0.1	None
		5000	0.0	0.0	0.0	None

 

Strain	+S9/-S9	Dose (µg/plate)	Mean (3)	SD	Ratio	Bacterial lawn
TA100	+S9	Solvent	138.3	18.9
		Negative	146.0	14.7	1.1
		Positive	2473.0	89.5	17.9
TA100	-S9	Solvent	121.0	12.5
		Negative	155.7	7.5	1.3
		Positive	667.3	44.1	5.5
TA1535	+S9	Solvent	9.7	2.9
		Negative	13.0	5.9	1.3
		Positive	129.3	9.6	13.3
TA1535	-S9	Solvent	7.7	0.6
		Negative	7.0	1.0	0.9
		Positive	290.3	21.9	37.7
TA1537	+S9	Solvent	17.7	1.5
		Negative	15..7	2.1	0.9
		Positive	411.3	43.4	23.2
TA1537	-S9	Solvent	14.7	1.2
		Negative	15.7	3.2	0.9
		Positive	151.3	12.7	8.5
TA98	+S9	Solvent	29.7	11.2
		Negative	27.0	5.3	0.9
		Positive	2446.3	202.4	82.4
TA98	-S9	Solvent	23.3	2.3
		Negative	24.3	3.2	1.0
		Positive	901.7	102.0	38.7

Second experiment:

Strain	+S9/-S9	Dose (µg/plate)	Mean (3)	SD	Ratio	Bacterial lawn
TA100	+S9	0	157.0	19.0
		20	172.3	1.5	1.1
		100	216.3	34.0	1.4
		300	274.7	21.5	1.7
		500	487.3	18.3	3.1
		1000	582.3	122.6	3.7
		2500	7.3	3.5	0.0	Incomplete
		5000	0.3	0.6	0.0	Incomplete
TA100	-S9	0	119.0	11.5	1.1
		4	133.7	6.1	1.1
		20	127.7	5.9	1.1
		100	129.7	10.2	1.1
		500	127.3	10.1	1.1
		2500	2.3	2.3	0.0	None
		5000	0.0	0.0	0.0	None
TA1535	+S9	0	13.3	3.2
		4	10.7	3.5	0.9
		20	14.7	3.2	1.1
		100	15.3	4.2	1.2
		500	11..3	1.5	0.8
		2500	3.3	1.5	0.2	Incomplete
		5000	0.0	0.0	0.0	Incomplete
TA1535	-S9	0	11.0	4.4
		4	8.3	0.6	0.8
		20	9.7	0.6	0.9
		100	12.3	2.5	1.1
		500	9.7	2.9	0.9
		2500	6.7	4.7	0.6	None
		5000	0.0	0.0	0.0	None
TA1537	+S9	0	12.0	2.6
		4	12.7	2.9	1.1
		20	16.3	3.2	1.4
		100	15.3	6.7	1.4
		500	15.0	1.7	1.3
		2500	4.0	1.0	0.3	Incomplete
		5000	0.0	0.0	0.0	Incomplete
TA1537	-S9	0	13.0	4.6
		4	11.0	4.6	0.8
		20	14.7	4.7	1.1
		100	16.7	1.5	1.3
		500	11.3	4.9	0.9
		2500	0.0	0.0	0.0	None
		5000	0.0	0.0	0.0	None
TA98	+S9	0	25.7	5.0
		20	38.3	6.1	1.5
		100	36.7	3.2	1.4
		300	53.0	7.0	2.1
		500	59.3	11.0	2.3
		1000	90.7	12.2	3.5
		2500	10.0	0.0	0.4	Incomplete
		5000	0.0	0.0	0.0	Incomplete
TA98	-S9	0	26.0	6.6
		4	24.7	5..8	1.0
		20	30.0	7.0	1.2
		100	32.0	8.7	1.2
		500	28.0	6.6	1.1
		2500	0.0	0.0	0.0	None
		5000	0.0	0.0	0.0	None

  

Strain	+S9/-S9	Dose (µg/plate)	Mean (3)	SD	Ratio	Bacterial lawn
TA100	+S9	Solvent	157.0	19.0
		Negative	158.3	6.7	1.0
		Positive	2198.0	103.1	14.0
TA100	-S9	Solvent	119.0	11.5
		Negative	143.0	7.9	1.2
		Positive	674.3	59.5	5.7
TA1535	+S9	Solvent	13.3	3.2
		Negative	13.3	3.1	1.0
		Positive	121.7	4.7	9.2
TA1535	-S9	Solvent	11.0	4.4
		Negative	10.7	4.7	1.0
		Positive	397.0	33.4	36.1
TA1537	+S9	Solvent	12.0	2.6
		Negative	15.3	5.5	1.3
		Positive	375.7	12.3	31.3
TA1537	-S9	Solvent	13.0	4.6
		Negative	20.0	1.0	1.5
		Positive	165.0	20.5	12.7
TA98	+S9	Solvent	25.7	5.0
		Negative	37.0	5.6	1.4
		Positive	2032.7	180.0	79.1
TA98	-S9	Solvent	26.0	6.6
		Negative	29.0	5.6	1.1
		Positive	1125.7	33.7	43.3

Applicant's summary and conclusion

Conclusions:

The substance was concluded to be mutagenic to Salmonellya typhimurium TA100 and TA98 in the presence of an exogenous metabolizing system.

Executive summary:

A bacterial reverse mutation assay (Ames test) was performed according to the OECD Guideline 471 (GLP study). Salmonella typhimurium strains TA100, TA1535, TA1537 and TA98 were exposed up to 5000 µg/plate test item in DMSO, both with and without metabollic activation. A plate incorporation method was used. After incubation for approximately 48 hours at approx. 37 ºC in the dark, colonies (his+ revertants) were counted. Two independent studies were performed (3 replicates/dose). Control plates without mutagen showed that the number of spontaneous reventant colonies was similar to that described in the literature. All the positive control compounds gave the expected increase in the number of reventant colonies. The test item poved to be toxic to most of the bacterial strains at a dose of 2500 µg/plate and above. In the cytotoxic experiment with the dilution of the Salmonella strain TA100 the test item proved to be toxic at a dose of 500 µg/plate (-S9) and 1000 µg/plate (+S9) and above. Test item did not show a dose dependent increase in the number of revertants in any of the bacterial strains without metabolic activation (-S9). In the presence of metabolic activation (+S9), relevant increases in the number of revertant colonies with the Salmonella strains TA100 and TA98 were observed. Based on these results, the substance was concluded to be mutagenic to Salmonellya typhimurium TA100 and TA98 in the presence of an exogenous metabolizing system.