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Toxicological information

Genetic toxicity: in vivo

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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-referenceopen allclose all
Reason / purpose for cross-reference:
reference to same study
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 guidelineopen allclose all
Qualifier:
according to guideline
Guideline:
OECD Guideline 486 (Unscheduled DNA Synthesis (UDS) Test with Mammalian Liver Cells in vivo)
Deviations:
no
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

Constituent 1
Chemical structure
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.