long chain alkyl thio carbamide metal complex

Genetic toxicity: in vitro

Administrative data

Endpoint:

in vitro cytogenicity / chromosome aberration study in mammalian cells

Remarks:

Type of genotoxicity: chromosome aberration

Type of information:

migrated information: read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

key study

Study period:

9 February to 12 April 1999

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Guideline study, to GLP, on related material

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

1999

Report date:

1999

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 473 (In Vitro Mammalian Chromosome Aberration Test)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Type of assay:

in vitro mammalian chromosome aberration test

Test material

Test material information

Constituent 1

Details on test material:

- Name of test material (as cited in study report): NB 6786-35
- Substance type: technical product
- Physical state: black viscous liquid
- Analytical purity: 94 ± 2% (based on a calculational method)
- Impurities (identity and concentrations): no data
- Composition of test material, percentage of components: tris(dicocodithiocarbamato) tris(μ-sulfido) (μ3-thio)-triangulotrimolybdenum (IV) dicocothiocarbamate
- Lot/batch No.: NB 6786-35
- Storage condition of test material: room temperature in dark

Method

Target gene:

not applicable

Species / strain

Species / strain / cell type:

lymphocytes: human

Details on mammalian cell type (if applicable):

not applicable

Additional strain / cell type characteristics:

not applicable

Metabolic activation:

with and without

Metabolic activation system:

post-mitochondrial fraction derived from the liver of Aroclor 1254-induced rats (S-9)

Test concentrations with justification for top dose:

Study 1 (without S9): 0, 39.06, 78.13, 156.25, 312.5, 625, 1250, 2500 and 5000 μg/ml
(with S9): 0, 50, 100, 150, 200, 250, 300, 400, 600 and 800 μg/ml

Study 2 (without S9): 0, 125, 250, 750, 1000, 2000, 3000 and 4000 μg/ml
(with S9): 0, 50, 100, 150, 200, 250, 300, 400, 600 and 800 μg/ml

Vehicle / solvent:

- Vehicle(s)/solvent(s) used: culture medium
- Justification for choice of solvent/vehicle: insoluble in water and acetone, but soluble in culture medium to about 10 mg/ml

Controls

Controls 1

Untreated negative controls:

no

Negative solvent / vehicle controls:

yes

Remarks:

culture medium

True negative controls:

no

Positive controls:

yes

Positive control substance:

mitomycin C

Remarks:

without S9

Migrated to IUCLID6: 0.1 μg/ml

Controls 2

Positive controls:

yes

Positive control substance:

cyclophosphamide

Remarks:

with S9

Migrated to IUCLID6: 6 μg/ml

Details on test system and experimental conditions:

METHOD OF APPLICATION: in medium

DURATION
- Exposure duration: (study 1): 3 hr both with and without S9;
(study 2): 3 hr with S9, 21 hr without S9
- Fixation time (start of exposure up to fixation or harvest of cells): 21 hr


SPINDLE INHIBITOR (cytogenetic assays): Colcemid
STAIN (for cytogenetic assays): 10% Giemsa

NUMBER OF REPLICATIONS: duplicate cultures

NUMBER OF CELLS EVALUATED: 100 per culture (200 per dose level)

DETERMINATION OF CYTOTOXICITY
- Method: mitotic index

OTHER EXAMINATIONS:
- Determination of polyploidy: yes
- Determination of endoreplication: no data

Evaluation criteria:

The assay was considered positive if statistically significant increases (P < 0.01) in the frequency of aberrations were observed at one or more concentrations and the increases were reproducible between the replicate cultures

Statistics:

Fisher exact test

Results and discussion

Test results

Species / strain:

lymphocytes: human

Metabolic activation:

with and without

Genotoxicity:

negative

Cytotoxicity / choice of top concentrations:

cytotoxicity

Vehicle controls validity:

valid

Untreated negative controls validity:

not examined

Positive controls validity:

valid

Additional information on results:

RANGE-FINDING/SCREENING STUDIES: study 1 was a range-finding study

COMPARISON WITH HISTORICAL CONTROL DATA: historical data on spontaneous levels and positive controls for January 1997 to December 1998 given in report

ADDITIONAL INFORMATION ON CYTOTOXICITY: see Table 1

Based on the mitotic indices the dose levels selected for metaphase analysis were:
Study 1: 1250, 2500 and 5000 μg/ml (without S9)
78.13, 156.25 and 312.5 μg/ml (with S9)
Study 2: 2000, 3000 and 4000 μg/ml (without S9)
400, 600 and 800 μg/ml (with S9)

There was no increase in polyploidy in treated cultures compared to the vehicle control.

Responses obtained from the negative and positive controls demonstrated that the system was capable of detecting chemicals that caused chromosomal damage.

Any other information on results incl. tables

Table 1. Summary of results

Exposure period (hr)	S9 mix	Concentration of test substance (μg/ml)	Cells with CAs excluding gaps (%)	Cells with CAs including gaps (%)	Mitotic index (%)
Study 1
3	-	0	0	1.0	100
		1250	0.5	1.5	94
		2500	0	3.0	78
		5000	0.5	1.0	37
		0.1 mitomycin C	13.5***	20.0***	-
3	+	0	0	1.0	100
		78.13	0.5	2.0	93
		156.25	1.0	2.0	114
		312.5	0	0.5	29
		6 cyclophosphamide	10.5***	19.5***	-
Study 2
21	-	0	0.5	0.5	100
		2000	0.5	1.0	92
		3000	0.5	1.5	85
		4000	1.0	2.0	58
		0.1 mitomycin C	13.5***	21.0***	-
3	+	0	0.5	0.5	100
		400	0.5	1.0	96
		600	0.5	1.5	81
		800	1.0	2.0	59
		6 cyclophosphamide	10.5***	17.0***	-

*** P <0.001

 

 

 

Applicant's summary and conclusion

Conclusions:

Interpretation of results (migrated information):
negative

In a GLP study conducted according to OECD guideline 473, EC# 434-650-5 - a substance structurally and chemically similar to EC# 457-3320-2 - showed no ability to induce chromosome aberrations or polyploidy in primary cultures of human lymphocytes, when tested at up to 800 or 5000 μg/ml with or without S9, respectively.

Executive summary:

In a GLP study conducted according to OECD guideline 473, the ability of EC# 434-650-5 (tris(dicocodithiocarbamato) tris(μ-sulfido) (μ3-thio)-triangulotrimolybdenum (IV) dicocothiocarbamate), a substance structurally and chemically similar to EC# 457-320-2, to cause chromosome aberrations was assessed in cultures of human lymphocytes.

Lymphocytes, obtained from healthy male volunteers, were grown in culture medium for 48 hr before the addition of the test substance, in the presence and absence of a rat liver metabolic activation fraction (S9). Two independent studies were carried out. In the first, up to 5000 or 800 μg/ml were incubated without or with S9, respectively, for 3 hr, before removal of the test substance and a further 18 hr incubation. In the second study up to 4000 or 800 μg/ml were incubated without or with S9, respectively, but in this case the cultures without S9 were exposed to the test substance for the entire 21 hr incubation period. Cell division was stopped in metaphase 2 hr before the end of the incubation period, after which the cells were fixed, stained with Giemsa and slides prepared. The proportion of mitoses (mitotic index) per 1000 cells were recorded and used to select the dose levels for scoring of chromosome aberrations. One hundred metaphases were scored for each duplicate culture.

No statistically significant increases in the number of chromosome aberrations or induction of polyploidy were observed with the test substance compared to the vehicle controls. Cytotoxicity was apparent as shown by the decrease in the mitotic indices of the treated cells at the higher dose levels, both with and without S9. The positive controls gave the expected response demonstrating the sensitivity of the test system.

In conclusion, EC# 434-650-5 showed no ability to induce chromosome aberrations or polyploidy in primary cultures of human lymphocytes, when tested at up to 800 or 5000 μg/ml with or without S9, respectively.

In view of the structural and chemical similarities, it is considered that the results of this study can be used for read-across to EC# 457-320-2.