Dibromomethane

Genetic toxicity: in vitro

Administrative data

Endpoint:

in vitro gene mutation study in bacteria

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

comparable to guideline study with acceptable restrictions

Cross-reference

Cross-reference 1

Reason / purpose for cross-reference:

exposure-related information

Reference

Endpoint:

in vivo insect germ cell study: gene mutation

Type of information:

experimental study

Adequacy of study:

weight of evidence

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

comparable to guideline study with acceptable restrictions

Reason / purpose for cross-reference:

exposure-related information

Reason / purpose for cross-reference:

exposure-related information

Qualifier:

no guideline followed

Principles of method if other than guideline:

Flies were kept in flasks containing approximately 8 ml of standard Drosophila melanogaster medium into which the desired amount of test material (non-specified purity, DBM) was injected through a rubber septum. The SLRL tests were carried out with treated adult male Drosophila melanogaster flies of a wild-type strain (Berlin K) that were 1-3 days old at the beginning of treatment. The treated males were mated with 3 virgin females of the Base strain and subsequently re-mated every 2 or 3 days with 3 fresh virgins up to a maximum of 5 such mating periods (broods). After short-term exposure, this mating procedure allows the separate sampling of germ-cell populations treated at different stages of their development.

GLP compliance:

no

Type of assay:

Drosophila SLRL assay

Species:

Drosophila melanogaster

Sex:

male/female

Vehicle:

standard Drosophila medium

Details on exposure:

Groups of 20-25 flies were kept in 1160 ml flasks containing approximately 8 ml of standard Drosophila medium into which the desired amount of test material (non-specified purity, DBM) was injected through a rubber septum. When treatment times exceeded 48 hours, the vessels were flushed every 2 or 3 days (fresh medium was given in the case of adult treatment) and a new dose of test material was introduced. The SLRL tests were carried out with treated adult male Drosophila melanogaster flies of a wild-type strain (Berlin K) that were 1-3 days old at the beginning of treatment. The treated males were mated with 3 virgin females of the Base strain and subsequently re-mated every 2 or 3 days with 3 fresh virgins up to a maximum of 5 such mating periods (broods). After short-term exposure, this mating procedure allows the separate sampling of germ-cell populations treated at different stages of their development.

Tissues and cell types examined:

For the detection of SLRL mutations, the standard scheme was performed.

Sex:

male/female

Genotoxicity:

negative

The results given at the table below demonstrate the number of mortalities per number of chromosomes test in each mating period (brood) and in total.

Frequencies of sex-linked recessive mortalities after treatment with DBM

	Expose. Time	Conc. (mg/m3)	Brood A nl/nchr^#%l	Brood B nl/nchr  %l	Brood C nl/nchr  %l	Brood D nl/nchr  %l	Brood E nl/nchr  %l	Brood A-E nl/nchr  %l
DBM	6h	60.2	0/396      0	1/386  0.26	1/396  0.25	0/394     0	0/392     0	2/1964  0.1

^#Number of lethal/number of chromosomes tested

Conclusions:

Interpretation of results: negative. DBM is not mutagenic when evaluated in the Drosophila melanogaster sex-linked recessive lethal test.

Executive summary:

In order to detect the occurrence of mutations, both point mutations and small deletions, in the germ line of an insect, the sex-linked recessive lethal (SLRL) test using Drosophila melanogaster was conducted.The inhalation route was selected by analogy to the human exposure situation.

Groups of 20-25 flies were kept in 1160 ml flasks containing approximately 8 ml of standard Drosophila medium into which the desired amount of test material (non-specified purity, DBM) was injected through a rubber septum. When treatment times exceeded 48 hours, the vessels were flushed every 2 or 3 days (fresh medium was given in the case of adult treatment) and a new dose of test material was introduced. The SLRL tests were carried out with treated adult male Drosophila melanogaster flies of a wild-type strain (Berlin K) that were 1-3 days old at the beginning of treatment. The treated males were mated with 3 virgin females of the Base strain and subsequently re-mated every 2 or 3 days with 3 fresh virgins up to a maximum of 5 such mating periods (broods). After short-term exposure, this mating procedure allows the separate sampling of germ-cell populations treated at different stages of their development. Upon long-term exposure, however, one may expect accumulation of damage according to the specific sensitivities of the stages through which the cells have proceeded during treatment. For the detection of SLRL mutations, the standard scheme was performed.

DBM is not mutagenic when evaluated in the Drosophila melanogaster sex-linked recessive lethal test.

Cross-reference 2

Reason / purpose for cross-reference:

exposure-related information

Reference

Endpoint:

genetic toxicity in vivo, other

Remarks:

DNA binding study in mammalians

Type of information:

experimental study

Adequacy of study:

weight of evidence

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

test procedure in accordance with generally accepted scientific standards and described in sufficient detail

Reason / purpose for cross-reference:

exposure-related information

Reason / purpose for cross-reference:

exposure-related information

Qualifier:

no guideline followed

Principles of method if other than guideline:

Rats and mice were treated i.p. with (14)C-dichloromethane, -dibromomethane, -1,2-dichloroethane, or -1,2-dibromoethane [5 mg (kg body weight)(-1)], and livers and kidneys were collected to rapidly isolate DNA. The DNA was digested using a procedure designed to minimize processing time, because some of the potential dihalomethane-derived DNA-glutathione (GSH) adducts are known to be unstable, and the HPLC fractions corresponding to major adduct standards were separated and analyzed for (14)C using accelerator mass spectrometry

GLP compliance:

not specified

Species:

rat

Strain:

Fischer 344

Details on species / strain selection:

also tested in mice strain B6C3F1

Sex:

male/female

Details on test animals or test system and environmental conditions:

2 males/dose/timepoint; Mice: 2/sex/timepoint; 24 control animals used but number/species and strain not stated.

Route of administration:

intraperitoneal

Vehicle:

Phosphate buffered saline

Frequency of treatment:

Once.

Post exposure period:

Animals sacrificed at 1 and 8 hrs after administration (method of sacrifice not stated). Kidneys and livers were removed with approximately 100 mg of each used for DNA
isolation and analysis.

Dose / conc.:

5 other: mg/kg/bw

Remarks:

(= 69 μCi/kg bw)

No. of animals per sex per dose:

Rats: 2 males/dose/timepoint; Mice: 2/sex/timepoint; 24 control animals used but number/species and strain not stated.

Control animals:

yes

Tissues and cell types examined:

Kidneys and livers

Sex:

male/female

Genotoxicity:

negative

Toxicity:

not specified

Vehicle controls validity:

valid

Negative controls validity:

valid

Positive controls validity:

valid

Conclusions:

None of four known (in vitro) GSH-DNA adducts was detected at a level of >2/10(8) - detection limit -DNA bases from dibromomethane

Data source

Reference

Reference Type:

publication

Title:

HPV1 TEST RULE STUDY – DATA ADEQUACY ASSESSMENTSRC TR-10-066 HPV1 TEST RULE STUDY – DATA ADEQUACY ASSESSMENT - Dibromomethane, CAS No. 74-95-3

Author:

Environmental Science Center
SRC, Inc

Year:

2010

Bibliographic source:

https://chemview.epa.gov/chemview/

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 471 (Bacterial Reverse Mutation Assay)

GLP compliance:

not specified

Type of assay:

bacterial reverse mutation assay

Test material

Test material information

1

Reference substance name:

Dibromomethane

EC Number:

200-824-2

EC Name:

Dibromomethane

Cas Number:

74-95-3

Molecular formula:

CH2Br2

IUPAC Name:

dibromomethane

Method

Species / strain

Species / strain / cell type:

other: TA97,TA98,TA100,TA104

Metabolic activation:

with and without

Test concentrations with justification for top dose:

0,10,25,50,100,250,500,1000 µg/plate

Vehicle / solvent:

DMSA

Controls

Untreated negative controls:

yes

Positive controls:

yes

Results and discussion

Test results

Test results 1

Species / strain:

other: TA97,TA98,TA100,TA104

Metabolic activation:

with

Genotoxicity:

positive

Cytotoxicity / choice of top concentrations:

not specified

Vehicle controls validity:

valid

Untreated negative controls validity:

valid

Positive controls validity:

valid

Test results 2

Species / strain:

other: TA98,TA100,TA104

Metabolic activation:

without

Genotoxicity:

positive

Cytotoxicity / choice of top concentrations:

not specified

Vehicle controls validity:

valid

Untreated negative controls validity:

valid

Positive controls validity:

valid