O-(4-bromo-2-chlorophenyl) O-ethyl S-propyl phosphorothioate

Genetic toxicity: in vivo

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

Study period:

11 July 1989 to 19 February 1990

Reliability:

1 (reliable without restriction)

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

1990

Report date:

1990

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

OECD Guideline 475 (Mammalian Bone Marrow Chromosome Aberration Test)

Version / remarks:

(1983)

Deviations:

no

Test guideline 2

Qualifier:

according to guideline

Guideline:

EU Method B.12 (Mutagenicity - In Vivo Mammalian Erythrocyte Micronucleus Test)

Version / remarks:

(1984)

Deviations:

no

Test guideline 3

Qualifier:

according to guideline

Guideline:

EPA OTS 798.5395 (In Vivo Mammalian Cytogenics Tests: Erythrocyte Micronucleus Assay)

Version / remarks:

(1987)

Deviations:

no

GLP compliance:

yes

Type of assay:

micronucleus assay

Test material

Test material information

Constituent 1

Reference substance name:

O-(4-bromo-2-chlorophenyl) O-ethyl S-propyl phosphorothioate

EC Number:

255-255-2

EC Name:

O-(4-bromo-2-chlorophenyl) O-ethyl S-propyl phosphorothioate

Cas Number:

41198-08-7

Molecular formula:

C11H15BrClO3PS

IUPAC Name:

4-bromo-2-chlorophenyl ethyl (propylsulfanyl)phosphonate

Test material form:

liquid

Test animals

Species:

mouse

Strain:

other: TRif: MAGF, SPF

Sex:

male/female

Administration / exposure

Route of administration:

oral: gavage

Duration of treatment / exposure:

single admin

Frequency of treatment:

once

Post exposure period:

16, 24, 48hr (16hr data discounted and not report due to insufficient sample time)

Doses / concentrations

Remarks:

Doses / Concentrations:50, 100, 200 mg/kgBasis:nominal conc.

No. of animals per sex per dose:

5 animals/sex/gp

Control animals:

yes, concurrent vehicle

Examinations

Tissues and cell types examined:

Micronuclei within polychromatic erthyrocytes (PCE) analysed for endpoint assessment and PCE and normochromatic erthyrocyte cells analysed for toxicity assessment

Results and discussion

Test results

Sex:

male/female

Genotoxicity:

negative

Toxicity:

no effects

Vehicle controls validity:

valid

Negative controls validity:

not applicable

Positive controls validity:

valid

Any other information on results incl. tables

RANGE-FINDING TEST:

Four males were dosed at 160, 200, 1000 and 5000 mg/kg. Animals were sacrificed at 3 days post the end of dosing. The following deaths were observed 0/4, 1/4, 4/4 and 4/4 respectively. The MTD was determined to be 160 mg/kg, however, in spite of the death observed a maximum dose of 200 mg/kg was selected for the micronucleus assay.

 

MICRONUCLEUS ASSAY

Five animals/sex/group were dosed using a dose volume of 20 mL/kg. Vehicle was 0.5% CMC.

 

Clinical observations:

No data reported

 

PCE ratio:

No evidence of cytotoxicity was observed.

 

Micronucleated polychromatic erythrocytes (MN PCE):

Analysis of the mean MN PCE group data from the first experiment indicated that there was no statistically significant increases MN PCE frequency compared to concurrent control values for either sex. Individual animal and group mean MN PCE frequencies were consistent with both the concurrent vehicle control values and the historical control. Positive control treatment induced the appropriate response

 

In the second experiment, whilst a significant increase (p<0.05) in MN PCE was observed for both male and female animals dosed at 50 mg/kg, this was due MNPCE values in both control groups being particularly low, with the increases not deemed biologically relevant. Furthermore, the slight increases observed were not accompanied by a decrease in %PCE values.

 

Table 7.6.2 -1: Summary of micronucleus results in male and female mice (24 and 48hr sample)

Dose group	Sex	Harvest time (h)	Mean %MN PCE/1,000 PCE	Mean %PCE
Vehicle	male	24	0.08	47
	female	24	0.14	45
Vehicle	male	48	0.08	46
	female	48	0.00	45
200	male	24	0.12	48
	female	24	0.08	39
200	male	48	0.06	40
	female	48	0.16	38
CPA	male	24	1.80	44
	female	24	2.48	42

 

Table 7.6.2 -2: Summary of micronucleus results in male and female mice (48hr sample)

Dose group	Sex	Harvest time (h)	Mean %MN PCE/1,000 PCE	Mean %PCE
Vehicle	male	48	0.02	45
	female	48	0.06	44
50	male	48	0.12*	49
	female	48	0.16*	46
100	male	48	0.08	45
	female	48	0.08	44
200	male	48	0.14	46
	female	48	0.08	47
CPA	male	24	1.54*	48
	female	24	0.88*	46

# Vehicle control,0.5% CMC(20 mL/kg body weight); positive control, cyclophosphamide (64 mg/kg)

* p<0.05

Applicant's summary and conclusion

Conclusions:

Interpretation of results (migrated information): negativeBased on the results from this study CGA 15’324 tech did not exhibit in vivo mammalian genotoxicity in male or female mouse bone marrow cells when tested up to a dose of 200 mg/kg (considered to exceed the MTD).

Executive summary:

In a bone marrow micronucleus assay usingTif: MAG., SPF mice, a single administered gavage dose of CGA 15'324 tech was administered to groups of male and female animals, employing a dose volume of 20 mL/kg. Doses were selected from a pilot toxicity study where four male mice were dosed at 160, 200, 1000 and 5000 mg/kg. The maximum tolerated dose was deemed to be 160 mg/kg, however, for an unexplained reason the maximum dose selected for the micronucleus assay was 200 mg/kg, with further doses of 50 and 100 mg/kg.

 

Negative control groups were treated with vehicle only (0.5% CMC), and positive control groups were treated with cyclophosphamide (CPA, 64 mg/kg). Mouse bone marrow was sampled at 24 and 48 hours after dosing for the vehicle, positive control and the highest dose group and again at 48hrs for the vehicle, positive control and all dose groups. A further sample time of 16 hours was also utilised, however as this sample time is considered too early, data from this sample time point has not been reported. Slides of bone marrow cells were prepared from five animals/sex/time point (where available) for each group and scored for the occurrence of micronucleated polychromatic erythrocytes (MN PCE) and PCE/total erythrocyte ratios.

 

One female dosed at 200 mg/kg died within the 48 hour treatment period (2^nd sample time) died prior to the scheduled necropsy. There were no marked decreases in mean PCE/total erythrocyte ratio observed for any of the CGA 15’324 tech treated groups compared to the vehicle control group for either time points.

 

Analysis of the mean MN PCE group data from the first experiment indicated that there was no statistically significant increases MN PCE frequency compared to concurrent control values for either sex. Individual animal and group mean MN PCE frequencies were consistent with both the concurrent vehicle control values and the historical control. Positive control treatment induced the appropriate response

 

In the second experiment, whilst a significant increase (p<0.05) in MN PCE was observed for both male and female animals dosed at 50 mg/kg, this was due MNPCE values in both control groups being particularly low, with the increases not deemed biologically relevant. Furthermore, the slight increases observed were not accompanied by a decrease in %PCE values Positive control treatment induced the appropriate response.

 

Based on the results from this study CGA 15’324 techdid not exhibit in vivo mammalian genotoxicity in male or female mouse bone marrow cells when tested up to a dose of 200 mg/kg (considered to exceed the MTD).