Chloramide

Genetic toxicity: in vivo

Administrative data

Endpoint:

in vivo mammalian somatic cell study: cytogenicity / bone marrow chromosome aberration

Remarks:

Type of genotoxicity: chromosome aberration

Type of information:

experimental study

Adequacy of study:

key study

Study period:

no data

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Comparable to guideline study with acceptable restrictions.

Data source

Reference

Reference Type:

publication

Title:

Evaluation of Chemicals used for drinking water disinfection for production of chromosomal damage and sperm-head abnormalities in mice.

Author:

Meier J.R., Bull R.J., Stober J.A., and Cimino M.C.

Year:

1985

Bibliographic source:

environmental Mutagenesis 7: 201-211

Materials and methods

Test guideline

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 475 (Mammalian Bone Marrow Chromosome Aberration Test)

Deviations:

yes

Remarks:

four animals per group instead of five. First prelevement at 6 hours after the treatment instead of 12-18h.

GLP compliance:

no

Type of assay:

chromosome aberration assay

Test material

Test material information

Constituent 1

Reference substance name:

Chloramide

EC Number:

234-217-9

EC Name:

Chloramide

Cas Number:

10599-90-3

Molecular formula:

ClH2N

IUPAC Name:

chloranamine

Details on test material:

Monochloramine (NH2Cl) solutions were prepared by slowly adding the NaOCl stock solution to 1.5 M NH4OH in a molar ratio 1:1. The concentration of chlorine was determine by iodometric titration (Method 409A) [American Public Health Association, 1975]. Solutions of chlorine for dosing animals were prepared by adjusting the pH with 2.5 N HCl to either 8.5 (predominant chlorine species: OCl-) or 6.5 (predominant chlorine species: HOCl), and diluting with distilled H2O to concentrations of 200 mg/l, 100 mg/l, and 40 mg/l in chlorine equivalents.

Test animals

Species:

mouse

Strain:

Swiss

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Charles River Breeding Laboratories, Inc.
- Age at study initiation: 8-11 week
- Weight at study initiation: no data
- Assigned to test groups randomly: yes
- Fasting period before study: no data
- Housing: animals, were group housed, separated by sex and by treatment group
- Diet: ad libitum
- Water : ad libitum
- Acclimation period: no data

ENVIRONMENTAL CONDITIONS
- Temperature (°C): no data
- Humidity (%): no data
- Air changes (per hr): no data
- Photoperiod (hrs dark / hrs light): no data

IN-LIFE DATES: no data

Administration / exposure

Route of administration:

oral: gavage

Vehicle:

- Vehicle(s)/solvent(s) used: deionized water

Details on exposure:

Animals were dosed by oral gavage with 1 ml of test solution on a subchronic regimen (five daily administration approximately 24hr apart). Concurrent negative controls received deionized water, the diluent of the test solutions. Positive controls were also included to ensure that the assay were working properly. Generally these were also concurrent. The intraperitoneal (IP) route was used for administration of the positive control chemicals since this route was found to be suitable for eliciting consistent, effective responses in all assays employed. In addition to the subchronic dosing regimen an acute administration was also employed in this assay.

Duration of treatment / exposure:

Five daily administrations approximately 24hr appart or an acute administration.

Frequency of treatment:

daily for the subchronic assay or one-time administration for the acute assy

Post exposure period:

Animals dosed acutely were sacrificed 6, 24, and 48 hr after exposure; animals dosed subchronically were sacrificed 6 hr after the last exposure.

Doses / concentrations

Remarks:

Doses / Concentrations:
0, 50, 100 and 200 mg/l
Basis:
nominal in water

No. of animals per sex per dose:

4

Control animals:

yes, concurrent no treatment

Positive control(s):

triethylenemelamine (1 mg/kg in 0.9 % saline)

Examinations

Tissues and cell types examined:

Bone marrow cells

Details of tissue and slide preparation:

DETAILS OF SLIDE PREPARATION:
After the last dose administration, animals were killed with CO2 or by cervical dislocation and the tibiae excised. The marrow was flushed from the bone into centrifuge tubes containing 3 ml of fetal calf serum. The marrow obtained in Hanks' balanced salt solution was treated, after centrifugation, successively with hypotonic (0.075 M) KCl and with fixative (3:1 methanol:acetic acid). After storage of the fixed material at 4°C for at least overnight, slides were prepared and stained with 5-10 % Giemsa at pH 6.8.

Evaluation criteria:

A mitotic index was determined by scoring the number of cells in mitosis based on at least 500 cells. Fifty metaphase spreads were scored for each animal where possible for structural and numerical aberrations. Numerical aberrations included cells showing either hyperploidy or polyploidy. Strutural aberrations included chromosome and chromatid breaks, chromatid deletions, fragments, translocations, triradials, quadriradials, pulverized chromosomes, pulverized cells, complex rearrangements, ring chromosomes, dicentric chromosomes, and minute chromosomes. Four endpoints were evaluated for statistically significant differences between the response at each treatment level and the concurrent negative control. The endpoints were (1) number of structural aberrations present per animal, (2) number of numerical aberrations present per animal, (3) percentage of cells with at least one structural aberration present per animal, and (4) percentage of cells with two or more structural aberrations per animal.Data for male anf female animals were analyzed both separately and combined.

Statistics:

A Student's t-test was used to test for differences between each treatment level and the current negative control. A significant level of 0.01 was used to indicate a positive response.

Results and discussion

Test results

Sex:

male/female

Genotoxicity:

negative

Toxicity:

not specified

Vehicle controls validity:

valid

Negative controls validity:

not examined

Positive controls validity:

valid

Additional information on results:

RESULTS OF DEFINITIVE STUDY
-- Types of structural aberrations for significant dose levels (for Cytogenetic or SCE assay): Negative

Applicant's summary and conclusion

Conclusions:

Interpretation of results (migrated information): negative
Under the conditions of this test, Monochloramine gave no significant increases in the number of strutural or numerical abberations for either pooled or individual sex data.

Executive summary:

The present study was carried out to determine whether monochloramine induce genotoxic effects following oral administration to mice. Then, a mouse bone marrow cytogenetics assay was conducted. Four males and four females were used for each treatment group (3 dose levels of the test solution and controls). Doses of 0, 50, 100 and 200 mg/l (nominal in water). Animals were dosed by oral gavage with 1 ml of test solution on a subchronic regimen (five daily administration approximately 24 hr apart.) or on a single acute dose administration. Concurrent negative controls received deionized water, the diluent of the test solutions. Positive controls were also included to ensure that the assays were working properly. The positive control was 1 mg/kg triethylenemelamine (TEM) in 0.9 % saline, administered via the intraperitoneal route as a one-time (acute) administration concurrently with the 24 hr acute component of the study.Three hours prior to sacrifice, animals were injected IP with 4.0 mg/kg colchicine to collect mataphases. Six hours after the last (fifth) dose administration (subchronic dosing) or 6, 24, and 48 hr (acute dosing), animals were killed and bone marrow were harvested. A mitotic index was determined by scoring the number of cells in mitosis based on at least 500 cells. Fifty metaphase spreads were scored for each animal where possible for structural and numerical aberrations. Numerical aberrations included cells showing either hyperploidy or polyploidy. Strutural aberrations included chromosome and chromatid breaks, chromatid deletions, fragments, translocations, triradials, quadriradials, pulverized chromosomes, pulverized cells, complex rearrangements, ring chromosomes, dicentric chromosomes, and minute chromosomes. Four endpoints were evaluated for statistically significant differences between the response at each treatment level and the concurrent negative control. The endpoints were (1) number of structural aberrations present per animal, (2) number of numerical aberrations present per animal, (3) percentage of cells with at least one structural aberration present per animal, and (4) percentage of cells with two or more structural aberrations per animal. Data for male anf female animals were analyzed both separately and combined. Under the conditions of this test, Monochloramine gave no significant increases in the number of strutural or numerical abberations for either pooled or individual sex data. The positive control chemical, TEM, induced a significant increases in both structural and numerical chromosomal aberrations relative to control.