Mercury

Genetic toxicity: in vivo

Administrative data

Endpoint:

in vivo mammalian germ cell study: cytogenicity / chromosome aberration

Remarks:

Type of genotoxicity: chromosome aberration

Type of information:

migrated information: read-across based on grouping of substances (category approach)

Adequacy of study:

key study

Study period:

no data available

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Well documented publication with some restriction: material and methods not described in detail

Data source

Reference

Reference 1

Reference Type:

publication

Title:

Effect of chlorophyllin on mercuric chloride-induced clastogenicity in mice.

Author:

Ghosh, A.K.; et al.

Year:

1991

Bibliographic source:

Food and Chemical Toxicology, 29(11):777–779.

Reference 2

Reference Type:

publication

Title:

Mammalian in vivo cytogenetic assay. Analysis of chromosome aberrations in bone marrow cells.

Author:

Preston, R.J.; et al.

Year:

1987

Bibliographic source:

Muatation Research 189, 157-165

Materials and methods

Test guideline

Qualifier:

equivalent or similar to guideline

Guideline:

other: Mamallian in vivo cytogenetic assays. Analysis of chromosome aberrations in bone marrow cells. (Preston, R.J.; et al., 1987, Mutation Research 189: 157-165)

Deviations:

not specified

GLP compliance:

no

Type of assay:

chromosome aberration assay

Test material

Test material information

Constituent 1

Reference substance name:

Mercury chloride

EC Number:

231-430-9

EC Name:

Mercury chloride

Cas Number:

7546-30-7

IUPAC Name:

mercury dichloride

Constituent 2

Reference substance name:

Mercury dichloride

EC Number:

231-299-8

EC Name:

Mercury dichloride

Cas Number:

7487-94-7

IUPAC Name:

mercury dichloride

Details on test material:

- Name of test material (as cited in study report): mercury chloride
- Molecular formula (if other than submission substance): HgCl2
- Physical state: solid
No further details are given.

Test animals

Species:

mouse

Strain:

Swiss

Sex:

male

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Swiss albino inbred mice were obtained from the Departmental animals house.
- Age at study initiation: 8-10 weeks
- Weight at study initiation: 25-28 g
- Housing: in cages
- Diet: standard diet
- Water: ad libitum

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 28 +/- 2
- Humidity (%): 60 +/- 5
- Photoperiod: 12 hours dark/light cycle
No further details are given.

Administration / exposure

Route of administration:

oral: gavage

Vehicle:

Vehicle(s)/solvent(s) used: distilled water

Details on exposure:

No further information available.

Duration of treatment / exposure:

single treatment

Frequency of treatment:

once

Post exposure period:

Animals were killed 24 hours after exposure.

Doses / concentrations

Doses / concentrations 1

Remarks:

Doses / Concentrations:
3.0 mg/kg body weight
Basis:
nominal in water
2.2 mg/kg bw Hg

Doses / concentrations 2

Remarks:

Doses / Concentrations:
6.0 mg/kg body weight
Basis:
nominal in water
4.4 mg/kg bw Hg

Doses / concentrations 3

Remarks:

Doses / Concentrations:
12.0 mg/kg body weight
Basis:
nominal in water
8.9 mg/kg bw Hg

No. of animals per sex per dose:

5 animals were used for each dose.

Control animals:

yes

Positive control(s):

Cyclophosphamide:
- Justification for choice of positive control(s): according to the followed guideline
- Route of administration: intraperitoneal
- Doses / concentrations: 25 mg/kg body weight

Examinations

Tissues and cell types examined:

Bone marrow

Details of tissue and slide preparation:

CRITERIA FOR DOSE SELECTION:
- Doses were equivalent to 1/40, 1/20 and 1/10 of the LD50 determined in the strain of mice used.

TREATMENT AND SAMPLING TIMES ( in addition to information in specific fields): no further details.

DETAILS OF SLIDE PREPARATION:
- Bone marrow chromosomes were prepared following a standard protocol: colchicine (4 mg/kg body weight; i.p.), hypotonic (1% sodium citrate), fixative (1:3 glacial acetic acid/ethanol) and flame drying.
- The slides were stained in diluted Giemsa stain.

METHOD OF ANALYSIS:
- 50 perfect metaphase plates were scored randomly per animal for chromosomal aberrations, and 1000 cells were scored for the mitotic index.
- All aberrations (chromatid gap, chromosome gap, chromatid break, chromosome break and rearrangement) were considered equal, irrespective of the number of events involved.
- The results are expressed as percentages of aberrant metaphase cells excluding gaps (%DC), and numbers of aberrations per cell excluding gaps (CA/cell).

Evaluation criteria:

no data

Statistics:

For all statistical analyses, the level of significance was established at P<0.05. A one-tailed trend test was performed to observe the effects of HgCl2. A one-way ANOVA test followed by Duncan's multiple range test was carried out to detect significant differences among different treatment protocols. Student's t-test was used to compare the mitotic index in the different sets of experiments.

Results and discussion

Test results

Sex:

male

Genotoxicity:

positive

Remarks:

HgCl2 at dose of 3, 6 and 12 mg/kg bw increased the frequency of CA (chromatid and isochromatid gaps, chromatid breaks). The number and percentage of damaged cells as well as the CA per cell were dose-dependently increased.

Toxicity:

yes

Remarks:

The mitotic indices were significantly and dose related decreased over the dose range investigated.

Vehicle controls validity:

valid

Negative controls validity:

not examined

Positive controls validity:

valid

Additional information on results:

No further details on results are available.

Any other information on results incl. tables

Table: Total chromosomal aberrations recorded following oral treatment of mice with mercury chloride.

Concentration [mg/kg body weight]	Total chromosomal aberrations						DC% (mean ± SEM)	CA/cell (mean ± SEM)	Mitotic index (mean ± SD)
	G’	G*	B’	B*	RR	DC
0	3	0	2	0	0	2	0.80 ± 0.49	0.008 ± 0.004	4.34 ± 0.11
3	18	1	9	0	1	10	4.0 ± 0.89	0.04 ± 0.008	3.78 ± 0.39§*
6	19	5	12	0	1	13	5.2 ± 1.01	0.052 ± 0.01	2.52 ± 0.19**
12	23	2	16	0	2	18	7.2 ± 0.79	0.072 ± 0.007	1.9 ± 0.48***
Positive control (25 mg/kg bw)	39	2	282	2	15	109	43.6 ± 9.53	1.188 ± 0.343	1.76 ± 0.44***

G’ and G* = chromatid and isochromatid gaps, respectively; B’ and B* = chromatid and chromosome breaks, respectively; RR = chromosomal arrangement; DC = damaged cells; SEM = standard error of the mean; SD = standard deviation.

§ = significant positive dose response obtained (P<0.001, one-tailed trend test).

* = indicates significant reductions in mitotic index compared with the negative control (* = P<0.05; ** = P<0.01 and *** = P<0.001; Student’s t-test).

Applicant's summary and conclusion

Conclusions:

Interpretation of results (migrated information): positive
Under the described test conditions and according to the given information the test substance mercury chloride showed mutagenic activity in the chromosome aberration test at all dose levels investigated.

Executive summary:

To evaluate the potential of mercury chloride to induce chromosome aberration in bone marrow cells, male mice were treated once with three different doses of the substance (per oral). The results showed that HgCl₂ at dose levels of 3, 6 and 12 mg/kg bw ( 2.2, 4.4 and 8.9 mg/kg bw/d Hg) increased the frequency of chromosomal aberrations (chromatid and isochromatid gaps, chromatid breaks). The number and percentage of damaged cells as well as the chromosomal aberrations per cell were dose-dependently increased. The mitotic indices were significantly and dose related decreased over the dose range investigated.