4,4'-bis(diethylamino)benzophenone

Genetic toxicity: in vivo

Administrative data

Endpoint:

in vivo mammalian somatic cell study: cytogenicity / erythrocyte micronucleus

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2003-03-19 to 2003-02-07

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Cross-reference

Reason / purpose for cross-reference:

read-across: supporting information

Reference

Endpoint:

in vivo mammalian somatic cell study: cytogenicity / erythrocyte micronucleus

Type of information:

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

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Justification for type of information:

REPORTING FORMAT FOR THE ANALOGUE APPROACH

1. HYPOTHESIS FOR THE ANALOGUE APPROACH
The following functional groups are common across the target and source substances: Aryl groups, Amine groups, and Carbonyl groups. It is the scientific hypothesis of this read-across justification that the presence of these functional groups dictates the mutagenic potential of the target substance. The target and sources substances all pass Lipinski’s rule of five and are therefore considered to have the potential to be absorbed into the body via the oral route. The breakdown products within the body are likely to be similar, or the same, as shown in the table below.
Breakdown products:

Source substance (4-Phenyl Benzophenone) - Benzophenone, Toluene, Hippuric acid or ortho-Cresol
Source substance (2-hydroxy-1-(4-(4-(2-hydroxy-2-methylpropionyl) benzyl) phenyl)-2-methylpropan-1-one) - Isobutyraldehyde + H2O, Benzyl benzene
Source substance (4,4'-bis(dimethylamino)benzophenone) - Benzophenone, Dimethylamine (x2)

Target substance - Benzophenone, Diethylamine (x2)

The target and source substances are expected to degrade in a similar way within the body and are expected to generate similar if not the same major metabolites. The molecular weight of the target and source substances are similar and are all below 500 daltons. There is some variation in the results of water solubility and partition coefficient between the target and source substances, this is not expected to impact the potential for genetic toxicity. Both the target and source substances pass Lipinski’s rule of five indicating that they may be orally absorbed and therefore are available within the body and may act in a genetically toxic way.


2. SOURCE AND TARGET CHEMICAL
The source and target substances are composed of the same functional groups bound together in similar ways. The molecular weight of the target and source substances are similar and they are expected to be absorbed in the body in similar ways. The breakdown products of the substance are expected to be the same or very similar and are expected to have the same potential for genetic toxicity.
The target and source substances contain very low levels of unidentified impurities. These impurities are considered not to affect the classification and labelling of the substance due to the very low levels at which they occur. No information on impurities present in the source test materials was available in the literature sources.
The impact of “impurities” is therefore considered not to affect the reliability of the read-across prediction.

3. ANALOGUE APPROACH JUSTIFICATION
Due to the similarities of the source and target substance with regards to physico-chemical properties, Lipinski’s rule of 5, and the fact that the target substance is expected to breakdown into structurally similar molecules in the body, the target substance is expected to behave in a substantially similar manner to the source substance.
The target substance is therefore predicted to be non-mutagenic in the in vivo OECD 476 study when conducted in the mammalian cells. By extension, the target substance is considered not to fulfil the criteria for mutagenicity under the Classification, Labelling, and Packaging (CLP) regulation (1272/2008).

4. DATA MATRIX
See appended full justification document.

Reason / purpose for cross-reference:

read-across source

Qualifier:

according to guideline

Guideline:

OECD Guideline 474 (Mammalian Erythrocyte Micronucleus Test)

Version / remarks:

adopted on 1997-07-21

Deviations:

no

Qualifier:

according to guideline

Guideline:

EU Method B.11 (Mutagenicity - In Vivo Mammalian Bone-Marrow Chromosome Aberration Test)

Deviations:

no

Sex:

male/female

Genotoxicity:

negative

Toxicity:

no effects

Vehicle controls validity:

valid

Negative controls validity:

not examined

Positive controls validity:

valid

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2003

Report date:

2003

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

OECD Guideline 474 (Mammalian Erythrocyte Micronucleus Test)

Version / remarks:

adopted on 1997-07-21

Deviations:

no

Test guideline 2

Qualifier:

according to guideline

Guideline:

EU Method B.11 (Mutagenicity - In Vivo Mammalian Bone-Marrow Chromosome Aberration Test)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Type of assay:

micronucleus assay

Test material

Test material information

Constituent 1

Reference substance name:

-

EC Number:

444-860-9

EC Name:

-

Cas Number:

474510-57-1

Molecular formula:

C21 H24 O4

IUPAC Name:

2-hydroxy-1-(4-(4-(2-hydroxy-2-methylpropionyl) benzyl) phenyl)-2-methylpropan-1-one

Test animals

Species:

mouse

Strain:

NMRI

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: RCC Ltd., Biotechnology and Animal Breeding Division, CH-4414 Rossdorf, Switzerland
- Age at start of acclimization: 8-10 weeks
- Weight at study initiation: males mean value 33.39 g and females mean value 27.13 g
- Assigned to test groups randomly: yes
- Fasting period before study: Approximately 18 hours before treatment the animals received no food but water ad
libitum
- Housing: Individuelly in Makrolon type- 1 cages
- Diet: pelleted standard diet, ad libitum (ALTROMIN 1324, D-32791 Lage/Lippe, Germany)
- Water: tap water, ad libitum, (Gemeindewerke, D-64380 Rossdorf, Germany)
- Acclimation period: minimum 5 days

ENVIRONMENTAL CONDITIONS
- Temperature: 22 ± 3 "C
- Humidity (%): 22 - 70 %
- Photoperiod: artificial light 6.00 a.m. - 6.00 p.m.

IN-LIFE DATES: From: To: 2003-01-04 until 2003-02-07

Administration / exposure

Route of administration:

oral: gavage

Vehicle:

Corn oil

Details on exposure:

PREPARATION OF DOSING SOLUTIONS: Not detailed

Duration of treatment / exposure:

Single dose

Frequency of treatment:

Once

Post exposure period:

Sampling of the bone marrow was done 24 hours after treatment (to animals administered with 500, 1000, and 2000 mg/kg bw.of the test item) and 48 hours after treatment (to animals administered with 2000 mg/kg bw)
acute toxic symptoms were examined at intervals of around 1 h, 2-4 h, 6 h, 24 h, 30 h, and 48 h after administration of the test item.

Doses / concentrations

Doses / concentrations 1

Dose / conc.:

500 mg/kg bw/day (nominal)

Doses / concentrations 2

Dose / conc.:

1 000 mg/kg bw/day (nominal)

Doses / concentrations 3

Dose / conc.:

2 000 mg/kg bw/day (nominal)

No. of animals per sex per dose:

10 animals (5 males, 5 females) per dose

Control animals:

yes, concurrent vehicle

Positive control(s):

Cyclophosphamide - 40 mg/kg b.w

Examinations

Tissues and cell types examined:

Erythrocyres from the bone marrow

Details of tissue and slide preparation:

- The femora were removed, the epiphyses were cut off and the marrow was flushed out with fetal calf serum, using a syringe. The cell suspension was centrifuged at 1500 rpm (390 x g) for 10 minutes and the supernatant was discarded. A small drop of the resuspended cell pellet was spread on
a slide. The smear was air-dried and then stained with May-Grunwald. Cover slips were mounted with EUKITT. At least one slide was made from each bone marrow sample
- Evaluation of the slides was performed using NIKON microscopes with 100 x oil immersion objectives. At least 2000 polychromatic erythrocytes (PCE) were analysed per animal for micronuclei. To describe a cytotoxic effect the ratio between polychromatic and total erythrocytes was determined in the same sample and expressed in polychromatic erythrocytes per 2000 erythrocytes. The analysis was performed with coded slides.

Evaluation criteria:

A test item was classified as mutagenic if it induced either a dose-related increase or a clear increase in the number of micronucleated polychromatic erythrocytes in a single dose group. Statistical methods (nonparametric Mann-Whitney test were used as an aid in evaluating the results. However, the primary point of consideration is the biological relevance of the results.
A test item that fails to produce a biological relevant increase in the number of micronucleated polychromatic erythrocytes is considered non-mutagenic in this system.

Statistics:

Nonparametric Mann-Whitney test

Results and discussion

Test results

Sex:

male/female

Genotoxicity:

negative

Toxicity:

no effects

Vehicle controls validity:

valid

Negative controls validity:

not examined

Positive controls validity:

valid

Additional information on results:

- After treatment with the test item the number of PCEs was not substantially decreased as compared to the mean value of PCEs of the vehicle control thus indicating that the test item did not exert any cytotoxic effects in the bone marrow
- In comparison to the corresponding vehicle controls there was no biologically relevant or statistically significant enhancement in the frequency of the detected micronuclei at any preparation interval after administration of the test item and with any dose level used
- Cyclophosphamide (positive control) administered orally was used as positive control which showed a substantial increase of induced micronucleus frequency.

Applicant's summary and conclusion

Conclusions:

Interpretation of results (migrated information): negative

Executive summary:

In this guideline (OECD 476) study conducted with GLP certification, the test material (EC 444-860-9) was determined not to be genotoxic. The test was conducted on mice (10 mice per sex per dose), with the substance administered via gavage in a single dose (nominal concentrations: 500, 1000 and 2000 mg/kg bw). The bone marrow of the test subjects was sampled at 24 and 48 hours. The results of the study indicate that the test material does not meet the criteria to be considered mutagenic under the EU Classification, Labelling, and Packaging (CLP) regulation (1272/2008).