Octylphosphonic acid

Genetic toxicity: in vivo

Administrative data

Endpoint:

in vivo mammalian cell study: DNA damage and/or repair

Type of information:

experimental study

Adequacy of study:

key study

Study period:

No data

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Cross-reference

Cross-reference 1

Reason / purpose for cross-reference:

reference to same study

Cross-reference 2

Reason / purpose for cross-reference:

reference to other study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

1997

Report date:

1997

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

OECD Guideline 486 (Unscheduled DNA Synthesis (UDS) Test with Mammalian Liver Cells in vivo)

Deviations:

no

Test guideline 2

Qualifier:

according to guideline

Guideline:

EU Method B.39 (Unscheduled DNA Synthesis (UDS) Test with Mammalian Liver Cells In Vivo)

Deviations:

no

Principles of method if other than guideline:

Not applicable.

GLP compliance:

yes (incl. QA statement)

Type of assay:

unscheduled DNA synthesis

Test material

Test material information

Constituent 1

Reference substance name:

Octylphosphonic acid

EC Number:

225-218-5

EC Name:

Octylphosphonic acid

Cas Number:

4724-48-5

Molecular formula:

C8H19O3P

IUPAC Name:

octylphosphonic acid

Test material form:

other: liquid

Details on test material:

Name in study report: Octylphosphonic Acid

Test animals

Species:

rat

Strain:

Sprague-Dawley

Sex:

male

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Strain: Alpk:APfSD
- Source: Rodent Breeding Unit (RBU), Zeneca, Alderley Park, Macclesfield, Cheshire
- Age at study initiation: 6-8 weeks
- Weight at study initiation: 215-277 g
- Fasting period before study: 6 hours or overnight
- Housing: individually
- Diet (e.g. ad libitum): ad libitum
- Water (e.g. ad libitum): ad libitum
- Acclimation period: at least 5 days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 21 +/- 3
- Humidity (%): 30-70
- Air changes (per hr): not available
- Photoperiod (hrs dark / hrs light): 12:12

IN-LIFE DATES: from 4 October 2004 to 14 December 2004

Administration / exposure

Route of administration:

oral: gavage

Vehicle:

- Vehicle(s)/solvent(s) used: corn oil
- Justification for choice of solvent/vehicle: acceptable solubility and non-toxicity to the animals
- Concentration of test material in vehicle: 10 ml/kg bw

Details on exposure:

PREPARATION OF DOSING SOLUTIONS: an individual stock emulsion of the test substance was prepared in corn oil for each group of animals.

DIET PREPARATION
- Rate of preparation of diet (frequency): not applicable
- Mixing appropriate amounts with (Type of food): not applicable
- Storage temperature of food: not applicable

Duration of treatment / exposure:

2 and 16 hours

Frequency of treatment:

once

Post exposure period:

not applicable

Doses / concentrations

Remarks:

Doses / Concentrations:
2000, 3200 mg/kg
Basis:
actual ingested

No. of animals per sex per dose:

4 (males only)

Control animals:

yes

Positive control(s):

2 hours preparation interval: DMH (N,N'-dimethylhydazinedihydrochloride)
- Justification for choice of positive control(s): validated for this assay
- Route of administration: oral gavage
- Doses / concentrations: 40 mg/kg bw / 10 ml/kg bw

16 hours preparation interval: 2-acetylaminofluorene
2 hours preparation interval: DMH (N,N'-dimethylhydazinedihydrochloride)
- Justification for choice of positive control(s): validatd for this assay
- Route of administration: oral gavage
- Doses / concentrations: 100 mg/kg bw / 10 ml/kg bw

Examinations

Tissues and cell types examined:

primary hepatocytes

Evaluation criteria:

a) Mean net nuclear grain counts for all test substance treated animals of less than zero - NEGATIVE.
b) In this laboratory no vehicle control animal has given a mean net nuclear grain count of greater than zero (Kennelly et al, 1995) and therefore such a value would be considered to represent a biologically significant departure from the norm. An occurrence of a mean net nuclear grain count of zero or above in a test substance treated animal is, therefore, considered to be indicative of a UDS response in that animal. Reproducibility of such a response in animals treated concurrently and in an independent experiment is necessary before concluding that the test substance is positive.
c) Where an individual animal has given rise to a mean net nuclear grain count of at least zero, but this is not fully reproducible, this may require further investigation.

Statistics:

not required.

Results and discussion

Test results

Sex:

male

Genotoxicity:

negative

Toxicity:

no effects

Vehicle controls validity:

valid

Negative controls validity:

not applicable

Positive controls validity:

valid

Additional information on results:

RESULTS OF RANGE-FINDING STUDY
- Dose range: 2000-5000 mg/kg
- Solubility: soluble in corn oil vehicle
- Clinical signs of toxicity in test animals: 4/5 mortalities at 5000 mg/kg. No mortality or clinical signs at 3200 mg/kg

Any other information on results incl. tables

Summary of Data

Treatment	Dose (mg/kg)	Number of animals	Mean N	SD	Mean C	SD	Mean (N-C)	SD	Mean % cells in repair
2 hours
Corn oil	10 ml/kg	2	5.6	3.1	8.6	4.2	-3.0	1.1	1
OPA	2000	5	4.3	1.4	7.2	2.6	-2.9	1.2	0
	3200	5	5.3	1.8	9.1	2.3	-3.7	0.6	1
DMH.2HCl	30	2	20.5	10.6	6.8	3.3	13.7	7.3	82
16 hours
Corn oil	10 ml/kg	2	4.0	0.5	7.9	0.6	-3.9	1.1	0
OPA	2000	5	3.9	0.6	7.1	1.7	-3.1	1.3	0
	3200	5	4.0	0.6	7.0	1.3	-3.0	0.7	0
DMH.2HCl	30	2	20.1	0.3	6.6	0.8	13.5	1.2	82

 

N: mean nuclear grain count

C: mean cytoplasmic grain count

(N-C): mean net nuclear grain count

SD: standard deviation

 

Individual Animal Data

 

Experiment 1 (16 hours)

Treatment	Dose (mg/kg)	Animal number	Mean N	Mean C	Mean (N-C)	SE	% cells in repair
Corn oil	10 ml/kg	1	4.4	7.56.4	-3.1	0.3	0
OPA	2000	3	3.6	6.4	-2.8	0.3	0
	2000	4	4.4	6.4	-2.0	0.4	1
	2000	5	3.2	5.1	-1.9	0.3	0
	3200	6	3.2	5.3	-2.0	0.3	0
	3200	7	4.0	6.9	-2.9	0.4	0
DMH.2HCl	30	8	19.9	7.3	12.6	1.2	80

 

Experiment 2 ( hours)

Treatment	Dose (mg/kg)	Animal number	Mean N	Mean C	Mean (N-C)	SE	% cells in repair
Corn oil	10 ml/kg	10	3.4	5.7	-2.3	0.3	1
OPA	2000	12	3.0	4.4	-1.4	0.2	0
	2000	13	2.8	4.9	-2.0	0.3	0
	2000	14	4.3	7.3	-3.0	0.4	0
	3200	15	4.0	7.0	-3.0	0.4	1
	3200	16	3.5	6.9	-3.4	0.3	0
DMH.2HCl	30	18	13.0	4.5	8.6	0.9	70

 

Experiment 3 (16 hours)

Treatment	Dose (mg/kg)	Animal number	Mean N	Mean C	Mean (N-C)	SE	% cells in repair
Corn oil	10 ml/kg	19	3.7	8.3	-4.6	0.4	0
OPA	2000	21	4.1	7.9	-3.8	0.5	0
	2000	22	4.6	9.5	-4.9	0.5	0
	3200	23	5.0	8.6	-3.7	0.4	1
	3200	24	3.7	6.5	-2.8	0.3	0
	3200	25	4.0	7.7	-3.7	0.4	0
DMH.2HCl	30	26	20.4	6.1	14.3	1.2	83

 

Experiment 4 ( hours)

Treatment	Dose (mg/kg)	Animal number	Mean N	Mean C	Mean (N-C)	SE	% cells in repair
Corn oil	10 ml/kg	29	7.8	11.6	-3.8	0.5	0
OPA	2000	30	5.7	10.3	-4.6	0.4	0
	2000	31	5.7	9.3	-3.5	0.4	0
	3200	32	7.9	12.4	-4.5	0.5	0
	3200	33	5.2	9.1	-3.8	0.4	0
	3200	34	6.1	10.1	-4.0	0.5	1
DMH.2HCl	30	36	28.1	9.2	18.9	1.3	93

N: nuclear grain count

C: cytoplasmic grain count

(N-C): net nuclear grain count

SE: standard error

Applicant's summary and conclusion

Conclusions:

negative
Under the conditions of test, OPA did not induce DNA repair (as measured by unscheduled DNA synthesis) in the rat liver in vivo.

Executive summary:

Octylphosphonic acid was evaluated, using an autoradiographic technique, for its ability to induce unscheduled DNA synthesis (UDS) in the liver of AlplcAPfSD rats. A single oral dose was given to groups of male rats at dose levels of 2000 and 3200 mg/kg. The latter dose level used represents the maximum tolerated dose (MTD) for male rats based on patterns of clinical signs and lethalities over a four day observation period. Two sampling times, 2 hours and 16 hours post-dose were used and 2 independent experiments were carried out at each time point.

The values recorded for the mean net nuclear grain counts and the percentage of cells in repair clearly show that OPA did not induce DNA repair, as measured by UDS, at either dose level or sampling time investigated. The test system positive control, 1,2-dimethylhydrazine dihydrochloride, induced marked increases in UDS, compared to the vehicle control values, thus demonstrating the sensitivity of the test system to a known genotoxin.

Under the conditions of test, OPA did not induce DNA repair (as measured by unscheduled DNA synthesis) in the rat liver in vivo.