Hexachlorocyclopentadiene

Genetic toxicity: in vivo

Administrative data

Endpoint:

in vivo mammalian germ cell study: cytogenicity / chromosome aberration

Type of information:

experimental study

Adequacy of study:

key study

Study period:

1978

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

comparable to guideline study with acceptable restrictions

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

1978

Report date:

1978

Materials and methods

Test guideline

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 478 (Genetic Toxicology: Rodent Dominant Lethal Test)

Deviations:

yes

Remarks:

Information on bodyweight and toxicity signs not recorded

GLP compliance:

no

Type of assay:

rodent dominant lethal assay

Test material

Test material information

1

Reference substance name:

Hexachlorocyclopentadiene

EC Number:

201-029-3

EC Name:

Hexachlorocyclopentadiene

Cas Number:

77-47-4

Molecular formula:

C5Cl6

IUPAC Name:

hexachlorocyclopentadiene

Test material form:

liquid

Test animals

Species:

mouse

Strain:

CD-1

Details on species / strain selection:

Random bred male and female mice

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Charles River Breeding Laboratories, Inc., Protage, Michigan
- Age at study initiation: at least 8 weeks
- Assigned to test groups randomly: yes
- Housing: Males housed individually and females housed in pairs (except when mating) in shoe box cages on AB-SORB-DRI bedding.
- Diet: Purina Lab Chow ad libitum
- Water: ad libitum
- Acclimation period: 2 weeks

ENVIRONMENTAL CONDITIONS
- Photoperiod: 12 hour light/dark cycle

Administration / exposure

Route of administration:

oral: gavage

Vehicle:

- Vehicle(s)/solvent(s) used: DMSO

Duration of treatment / exposure:

Male mice exposed to several dose levels of test compound over 5 days

Frequency of treatment:

Daily

Post exposure period:

Rested for 2 days following treatment, then mated weekly for 7 weeks.

Doses / concentrations

Doses / concentrations 1

Dose / conc.:

1 mg/kg bw/day (nominal)

Doses / concentrations 2

Dose / conc.:

0.3 mg/kg bw/day (nominal)

Doses / concentrations 3

Dose / conc.:

0.1 mg/kg bw/day (nominal)

No. of animals per sex per dose:

10 random bred mice assigned to 1 of 5 groups. Three groups received different dose levels of hexachlorocyclopentadiene; a fourth group received only the solvent; a fifth group received a known mutagen as the positive control. Following treatment, each male was mated with 2 virgin females which were replaced weekly for 7 weeks.

Control animals:

yes, concurrent vehicle

yes, sham-exposed

yes, historical

Positive control(s):

Triethylenemelamine (TEM)
- Justification for choice of positive control(s):
- Route of administration: single intraperitoneal injection

Examinations

Details of tissue and slide preparation:

CRITERIA FOR DOSE SELECTION: Range finding studies were conducted to calculate dose information. LD50, LD5 and LD1 concentrations were computer generated based on the preliminary study. The high dose level was selected from these data; 1/3rd and 1/10th of the high dose were used as the intermediate and low dose levels respectively.

TREATMENT AND SAMPLING TIMES: Male mice were exposed to the test compound for 5 days then mated over the entire period of spermatogenesis to unexposed virgin females. At mid-pregnancy the females were killed and scored for number of living and dead implants, as well as fertility level.

METHOD OF ANALYSIS: The number of dead and living fetuses, resorption sites, and total implantation sites were recorded. Data were analysed for statistical significance. Results were compared to data from control animals and used to determine the degree of induced dominant lethality.

Evaluation criteria:

Dominant lethality is determined from:
a) a mutation index derived from dead to total implants; or
b) the number of dead implants per pregnant female

Statistics:

See attached background material.

Results and discussion

Test results

Key result

Sex:

male/female

Genotoxicity:

negative

Toxicity:

yes

Remarks:

A preliminary test was performed in order to determine the toxicity of the substance and adapt the final doses selected

Vehicle controls validity:

valid

Negative controls validity:

valid

Positive controls validity:

valid

Additional information on results:

RESULTS OF RANGE-FINDING STUDY
- Dose range: 50 mg/kg to 5000 mg/kg (first trial). 7.6 mg/kg to 76 mg/kg (second trial).
- Clinical signs of toxicity in test animals: Mortality occurred at all the doses investigated. All animals died at 76 mg/kg and above.

Any other information on results incl. tables

See attached background material for full results table.

Applicant's summary and conclusion

Conclusions:

Hexachlorocyclopentadiene was not active in this Mouse Dominant Lethal Assay.

Executive summary:

A mouse dominant lethal assay was performed to determine the potential of the assay to induce structural and numerical chromosome aberrations according to a method similar to the OECD Tetsing Guideline 478 (non-GLP) with deviations.

Hexachlorocyclopentadiene was tested for toxicity over a range of 50 mg/kg to 5,000 mg/kg. Based on this toxicity and acute LD50 level of 76 mg/kg was calculated. The high dose was selected as the LD50 and concentrations of 25.3 mg/kg and 7.6 mg/kg were employed as the two lower doses levels. These concentrations proved to be too toxic for a five-day exposure since all ten animals died before five days. A second LD50 was calculated and identified 1 mg/kg as the high dose and 1/3 and 1/10 of the LD50 levels for the study.

The test material was examined for its ability to induce dominant lethality in mice treated with 0.1, 0.3 and 1.0 mg/kg bw/d for five days.

There was no evidence for significant dominant lethal activity by Hexachlorocyclopentadiene in mice. All data were within the concurrent and historical control levels. The positive control compound produced the expected dominant lethal effects in the first three mating weeks. Hexachlorocyclopentadiene was not active in the Mouse Dominant Lethal Assay conducted as part of this evaluation.