Registration Dossier

Administrative data

Endpoint:
in vivo mammalian germ cell study: cytogenicity / chromosome aberration
Remarks:
Type of genotoxicity: chromosome aberration
Type of information:
read-across based on grouping of substances (category approach)
Adequacy of study:
key study
Study period:
1977
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: The study was not conducted according to guideline/s and GLP, but the report contains sufficient data for interpretation of study results
Justification for type of information:
Please see read across justification document.
Cross-referenceopen allclose all
Reason / purpose:
reference to same study
Reason / purpose:
reference to other study

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
1977

Materials and methods

Test guideline
Qualifier:
no guideline followed
Principles of method if other than guideline:
Similar to: Buckton, K.E. and B. J. Evans. Methods for the Analysis of Human Chromosome Aberrations. World Health Organization, Geneva (1973).
GLP compliance:
no
Remarks:
pre-GLP
Type of assay:
other: cytogenetic effects on rat bone marrow cells

Test material

Reference
Name:
Unnamed
Type:
Constituent
Test material form:
solid: particulate/powder
Remarks:
migrated information: powder
Details on test material:
Dowfax Surfactant XD-8390
Purity: 92.5% active
Appearance: fine hydroscopic powder
Composition: 92.5% active, 5.4% NaCl, 2.1% Na2SO4 and 7.5 ppm iron

Test animals

Species:
rat
Strain:
Sprague-Dawley
Sex:
male/female
Details on test animals and environmental conditions:
Groups of 5 Sprague-Dawley (Spartan substrain) rats/sex

Administration / exposure

Route of administration:
oral: feed
Vehicle:
None- Undiluted, dried material
Details on exposure:
The Dowfax 8390 surfactant identified as XD-8390 is a 36% aqueous solution of disodium hexadecyldiphenyl oxide disulfonate.
For incorporation in the diet of rats, the solution was dried to a fine hydroscopic powder which contained 92.5% active ingredient, 5.4% NaCl, 2.1% Na2S04 and 7.5 ppm iron. The test diets were prepared weekly with the concentration of powdered XD-8390 adjusted according to the rate of food consumption and body weight change to maintain the designated dose levels on a mg/kg body weight/day basis.

For this cytogenetic study, five groups of 5 male Sprague-Dawley (Spartan substrain) rats and five groups of 5 female rats were fed diets (Purina Laboratory Chow) containing amounts of XD-8390 calculated to provide dosages of 0, 50, 100, 200 or 600 mg/kg body weight per day for 90 days.
Duration of treatment / exposure:
90 days
Frequency of treatment:
Daily
Post exposure period:
None
Doses / concentrations
Remarks:
Doses / Concentrations:
0, 50, 100, 200 or 300 mg/kg/day
Basis:
nominal in diet
No. of animals per sex per dose:
5
Control animals:
yes, plain diet
Positive control(s):
No

Examinations

Tissues and cell types examined:
Bone marrow cells
Details of tissue and slide preparation:
After the 90-day treatment, bone marrow cells fromall the rats were processed. The methods used for the chromosome analysis are similar to those described in ''Methods for the Analysis of Human Chromosomal Aberrations" published by the World Health Organization.

The slides were coded so that the identity of the animal was unknown to the scorer. The plan was to score 50 metaphase spreads per animal, and only diploid (2n=42) or 2n-1 cells were scored.

Cell Collection and Preparation
1. The rats were injected intraperitoneally with colchicine (0.4 mg/kg) four hours before being decapitated. The head of the femur was removed and the bone marrow was aspirated using a 10 cc syringe and a 20 gauge needle.
2. The bone marrow cells were mixed in 10 ml Hank's balanced salt solution using a disposable pipette.
3. The cells were centrifuged at 2000 RPM for 10 minutes.
4. The Hank's balanced salt solution was removed and 10 ml of 0.4% KC1 was added to the tubes. They were then incubated for 20 minutes in a 37C water bath. ( Critical )
5. The cells were then centrifuged for 10 minutes at 2000 RPM .
6. The supernatant was removed and a 3:l methanol/acetic acid fixative was used to resuspend the cells.
7 . The cells were then stored at 4C for later preparation of slides.

B. Slide Preparation
1. Centrifuge as in A-3 above, decant the fixative and add fresh 3:1 fixtive.
2. Remove the slides and place approximately 5 drops of a cell suspension on a slide; pass the slide through a flame. The slides were then dried on a warming plate at 60°.
3. The slides were rinsed gentley in distilled H20 and were placed in Giemsa stain for 10 minutes. Dehydration was through 2 acetone washes, 2 acetone-xylol changes. The slides were coverslipped from xylol using Harleco Synthetic Resin (HSR) as a mounting medium and were dried in an oven overnight.
Evaluation criteria:
The plan was to score 50 metaphase spreads per animal, and only diploid (2n=42) or 2n-1 cells were scored.
Statistics:
None

Results and discussion

Test results
Sex:
male/female
Genotoxicity:
negative
Toxicity:
not specified
Vehicle controls validity:
valid
Negative controls validity:
valid
Positive controls validity:
not examined
Additional information on results:
A careful analysis of 50 metaphase spreads from each of the 25 male rats revealed no chromosomal aberrations among the 1250 cells examined. Analysis of 1244 spreads from the 25 female rats revealed only one aberration (a chromatid break) in one animal at the 100 mg/kg dose level. Although this abnormality was found in atreated animal, it is probably inconsequential because in similar studies with this strain of rats, 27 of 3750 cells (0.72%) from 100 untreated control rats contained one or more abnormalities. When this strain of rats was treated with a potent mutagen (triethylene-melamine), 55% of the bone marrow cells contained abnormal chromosomes.

Any other information on results incl. tables

None

Applicant's summary and conclusion

Conclusions:
Interpretation of results (migrated information): negative
No significant difference was found in the aberration rate of metaphase chromosomes of the treated and control animals.
Executive summary:

INTRODUCTION: This cytogenetic study was conducted as a supplement to a subchronic toxicity study to determine if chromosomal aberrations are induced in rats ingesting DOWFAX XD-8390 at various concentrations in the diet for 90 days.

MATERIALS AND METHODS: Five groups of 5 male Sprague-Dawley rats and five groups of 5 female rats were fed diets containing amounts of DOWFAX XD-8390 calculated to provide dosages of 0, 50, 100, 200 or 600 mg/kg bw per day for 90 days. After the 90-day treatment, bone marrow cells from all rats were processed. The slides were coded. The plan was to score 50 metaphase spreads per animal, and only diploid (2n=42) or 2n-1 cells were scored.

RESULTS AND DISCUSSION: A careful analysis of the 50 metaphase spreads from each of the 25 male rats revealed no chromosomal aberrations among the 1250 cells examined. Analysis of the 1244 spreads from the 25 female rats revealed only one aberration (a chromatid break) in one animal at the 100 mg/kg dose level. Although this abnormality was found in a treated animal, it is inconsequential because of historical control data in similar studies with this strain of rat, where 27 of 3750 cells (0.72%) from 100 untreated control rats contained one or more abnormalities. When this strain of rat was treated with a potent mutagen (triethylenemelamine), 55% of the bone marrow cells contained normal chromosomes.

SUMMARY: The cytogenetic effects of DOWFAX Surfactant XD-8390 were determined on bone marrow cells of rats fed diets containing sufficient quantity of the test material to provide doses of 0, 50, 100, 200 or 600 mg/kg bw/day for 90 days. No significant difference was found in the aberration rate of metaphase chromosomes of the treated and control animals.