Chlorimuron ethyl

Genetic toxicity: in vitro

Administrative data

Endpoint:

in vitro gene mutation study in bacteria

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

test procedure in accordance with national standard methods

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

1993

Report date:

1993

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

other: Mutagenicity Test in Industrial Safety and Health Law (1991), Ministry of labor of Japan, Japan Industrial Safety and Health Association, Tokyo.

Deviations:

no

Principles of method if other than guideline:

The reverse mutation test was done by preincubation method.

GLP compliance:

yes

Type of assay:

bacterial reverse mutation assay

Test material

Test material information

Constituent 1

Reference substance name:

ethyl 2-({[(4-chloro-6-methoxypyrimidin-2-yl)carbamoyl]amino}sulfonyl)benzoate

EC Number:

618-690-2

Cas Number:

90982-32-4

Molecular formula:

C15H15ClN4O6S

IUPAC Name:

ethyl 2-({[(4-chloro-6-methoxypyrimidin-2-yl)carbamoyl]amino}sulfonyl)benzoate

Test material form:

solid

Details on test material:

- Purity: 98.5%

Method

Species / strain

Species / strain 1

Species / strain / cell type:

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

Species / strain 2

Species / strain / cell type:

E. coli WP2 uvr A

Metabolic activation:

with and without

Metabolic activation system:

Rat liver homogenate

Test concentrations with justification for top dose:

Dose finding test: 0, 156, 313, 625, 1250, 2500 & 5000 µg/plate
Main study: 0.02 to 313 µg/plate for Salmonella strains; 313 to 5000 µg/plate for Escherichia strain

Vehicle / solvent:

- Vehicle used: DMSO

Controls

Negative solvent / vehicle controls:

yes

Remarks:

DMSO

Positive controls:

yes

Positive control substance:

9-aminoacridine

sodium azide

N-ethyl-N-nitro-N-nitrosoguanidine

other: 2-aminoanthracene and 2-(2-furyl)-3-(5-nitro-2-furyl)acrylamide

Details on test system and experimental conditions:

The reverse mutation test was done by preincubation method.
Stock cultures of tester strains were inoculated against the liquid growth medium and grown with shaking at 37°C for 8 hours. Densities of the fresh bacterial cultures were measured with turbidometer. 0.1 ml of a test solution, a 0.1 ml aliquot of one of the bacterial suspensions and 0.5 ml of either S9 mix for assay with metabolic activation or 0.1 M sodium-phosphate buffer (pH 7.4) for assay without metabolic activation were mixed in a sterilized test tube and incubated with gentle shaking at 37°C for 20 min. After preincubation, 2 ml of molten top agar was added to this mixture and then poured onto a minimal glucose agar plate. When the agar overlay solidified, these plates were incubated at 37°C for 48 hours. Two plates per one dose level were used for each assay. Revertant colonies were counted with the eye or a colony counter. The presence of the background lawn was observed using a stereoscopic microscope and microbial growth was checked.

Evaluation criteria:

The test substance is positive in this assay when the mean number of revertants is more than double of the negative control value and when it increases significantly dose-dependent.

Results and discussion

Test results

Key result

Species / strain:

other: S. typhimurium strains TA1535, TA1537, TA98, TA100 and E. coli WP2 uvrA

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

cytotoxicity

Vehicle controls validity:

valid

Positive controls validity:

valid

Additional information on results:

RANGE-FINDING STUDIES:
Preliminary tests with the highest dose level of 5000 µg per plate showed that microbial toxicity was observed against the S. typhimurium strains, but not against the E. coli strain. Based on these results, seven dose levels including the dose level to cause the microbial growth inhibition were selected for the S. typhimurium strains. For the Escherichia coli strain five dose level of 313 to 5000 µg per plate were selected.

Any other information on results incl. tables

Results of the main test (1st test) without S9 mix

Test substance concentration (µg/plate)	Number of revertants (number of colonies/plate)
	Base-pair change type			Frameshift type
	TA100	TA1535	WP2 uvrA-	TA98	TA1537
Solvent control	88	9	15	11	8
0.02		5
0.04		10
0.08		8			6
0.15		12		11	2
0.3		5		8	4
0.6		4		13	2
1.2		0		8	3
2.4				7	1
4.9	44			6	1
9.8	43			0
20	35
39	26
78	0
156	0
313	0		15
625			14
1250			17
2500			18
5000			15
Positive control	AF-2	NaN3	ENNG	AF-2	9-AA
Concentration (µg/plate)	0.01	0.5	2	0.1	80
Number of revertants	591	308	513	216	683

Results of the main test (1st test) with S9 mix

Test substance concentration (µg/plate)	Number of revertants (number of colonies/plate)
	Base-pair change type			Frameshift type
	TA100	TA1535	WP2 uvrA-	TA98	TA1537
Solvent control	59	7	22	22	7
0.02
0.04		11
0.08		9			9
0.15		12		25	5
0.3		10		19	2
0.6	58	3		13	2
1.2	58	0		15	0
2.4	25	0		7	0
4.9	10			5	0
9.8	8			0
20	0
39	0
78
156
313			20
625			22
1250			19
2500			17
5000			21
Positive control	2-AA	2-AA	2-AA	2-AA	2-AA
Concentration (µg/plate)	1	2	10	0.5	2
Number of revertants	1420	322	914	319	270

Results of the main test (2nd test) without S9 mix

Test substance concentration (µg/plate)	Number of revertants (number of colonies/plate)
	Base-pair change type		Frameshift type
	TA100	TA1535	TA98	TA1537
Solvent control	67	5	12	8
0.02		5
0.04		5
0.08		4		5
0.15		5	9	5
0.3		5	12	3
0.6		2	9	3
1.2	65	0	8	0
2.4	52		3	0
4.9	49		0
9.8	27		0
20	40
39	41
78	0
Positive control	AF-2	NaN2	AF-2	9-AA
Concentration (µg/plate)	0.01	0.5	0.1	80
Number of revertants	298	259	319	571

Results of the main test (2nd test) with S9 mix

Test substance concentration (µg/plate)	Number of revertants (number of colonies/plate)
	Base-pair change type		Frameshift type
	TA100	TA1535	TA98	TA1537
Solvent control	73	12	24	10
0.02
0.04		8
0.08		6		7
0.15		6	20	6
0.3	78	4	18	5
0.6	58	4	15	3
1.2	42	2	13	0
2.4	36	0	15	0
4.9	38		8	0
9.8	21		0
20	0
Positive control	2-AA	2-AA	2-AA	2-AA
Concentration (µg/plate)	1	2	0.5	2
Number of revertants	1135	355	609	217

Applicant's summary and conclusion

Conclusions:

The test substance was not mutagenic when tested in S. typhimurium and E. coli strains, with and without metabolic activation system.

Executive summary:

The test substance was examined for the mutagenicity in bacterial assays using five different bacterial strains of Salmonella typhimurium TA98, TA100, TA1535, TA1537, and Escherichia coli WP2 uvrA. The test was performed at five to seven dose levels of 0.02 to 5000 µg per plate. The number of revertants induced by the test substance in each strain was less than double of the solvent control value.

These findings led the conclusion that the test substance is not mutagenic under the test conditions employed.