Benzene, (1-methylethyl)-, oxidized, polyphenyl residues

Genetic toxicity: in vivo

Administrative data

Endpoint:

in vivo mammalian somatic cell study: cytogenicity / erythrocyte micronucleus

Remarks:

Type of genotoxicity: chromosome aberration

Type of information:

other: read-across from most toxic ingredient

Adequacy of study:

weight of evidence

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: see 'Remark'

Remarks:

Study is comparable to OECD 474 with acceptable restrictions (party limited documentation, e.g. no details on test substance, vehicle, concentration of phenol in vehicle; data taken from a poster presented at the 42nd Annual Meeting of the Society of Toxicology, 09. - 13.03.2003 in Salt Lake City, Utah, USA)

Data source

Reference

Reference 1

Reference Type:

publication

Title:

Hypothermia following treatment of mice with phenol is not reversed by thermoregulatory support: implications for micronucleus (MN) formation

Author:

Spencer PJ, Grundy JG, Gollapudi BB, Waechter JM, Gingell RR, Dimond SS, Dunn BJ

Year:

2003

Bibliographic source:

Toxicologist 72: 207

Reference 2

Reference Type:

other: poster presentation

Title:

Hypothermia following treatment of mice with phenol cannot be reversed by thermoregulatory support: implications for micronucleus (MN) formation

Author:

Spencer PJ, Grundy JG, Gollapudi BB, Waechter JM, Gingell RR, Dimond SS, Dunn BJ

Year:

2003

Bibliographic source:

Poster presented at the 42nd Annual Meeting of the Society of Toxicology, 09. - 13.03.2003 in Salt Lake City, Utah, USA

Materials and methods

Test guideline

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 474 (Mammalian Erythrocyte Micronucleus Test)

Deviations:

no

GLP compliance:

not specified

Type of assay:

micronucleus assay

Test material

Test material information

Constituent 1

Reference substance name:

Phenol

EC Number:

203-632-7

EC Name:

Phenol

Cas Number:

108-95-2

Molecular formula:

C6H6O

IUPAC Name:

phenol

Test material form:

solid: crystalline

Details on test material:

No details given

Test animals

Species:

mouse

Strain:

CD-1

Sex:

male/female

Details on test animals or test system and environmental conditions:

8 week old male & female CD1 mice, housed in standard environment or a supported environment.

Standard environment
Housing: hanging wire cages
Room temperature/humidity: 21-23°C/40-60%

Thermoregulatory support conditions
Housing: plastic “shoebox” style cages with corn cob bedding & a small nesting hut, warming blanket at 30°C placed under half of the cage
Room temperature/humidity: 28-30°C/27-47%

No further data

Administration / exposure

Route of administration:

intraperitoneal

Vehicle:

no data

Details on exposure:

No details

Duration of treatment / exposure:

single injection

Frequency of treatment:

sigle application

Post exposure period:

24 or 48 h

Doses / concentrations

Remarks:

Doses / Concentrations:
0 or 300 mg/kg bw
Basis:
no data

No. of animals per sex per dose:

Data on MN induction: not documented (but presumably surving mice, see Table below on mortality).
Data on mortality: 10 mice per sex in control and 24 mice per sex in treated group.

Control animals:

yes, concurrent vehicle

Positive control(s):

120 mg/kg bw cyclophosphamide monohydrate (only males)

Examinations

Tissues and cell types examined:

Body temperature measured 0, 24, 48 h after application.
Mortality rate recorded.
MN per/1000 PCE determined in preparations of the bone marrow tissue 24 or 48 h after application.

Details of tissue and slide preparation:

No details

Evaluation criteria:

No data

Statistics:

Statistical analysis performed (no details except level of significance, a<0.05).

Results and discussion

Test results

Sex:

male/female

Genotoxicity:

positive

Toxicity:

yes

Vehicle controls validity:

valid

Positive controls validity:

valid

Additional information on results:

Body Temperature (BT) of CD1 Mice after Phenol Treatment
Standard Environment: in males and females the BT decreased to ca. 31.5°C 24 h after application of 300 mg/kg bw; BT of 29°C in males and ca. 30.5 in females were measured 48 h after application. At the same time only a slight decrease in BT of ca. 1°C was detected in male and female mice using thermoregulative support.

Mortality
A significant increase in lethality in phenol-treated mice with thermoregulatory support was observed (see Table below) which might indicate a protective role of hypothermia against lethality.

Micronuclei (MN) induction
Thermoregulatory support did not prevent MN induction in phenol-treated mice at 24 h post-dosing but at 48 h post-dosing.
The frequency of MN-PCE increased at 48 h as compared to the frequency at 24 h in phenol-treated unsupported mice. A slight but not significant increase in MN occurred in the thermoregulatory supported control male mice at 24 h but not 48 h. BT measurement at 0, 24 and 48 h did not allow full characterization of BT profiles.

Any other information on results incl. tables

Mortality in phenol-treated mice

Dose in mg/kg bw	Mortality in males	Mortality in females
	Unsupported thermoregulation
0	0/10	0/10
300	5/24	1/24
-	Supported thermoregulation
0	1/10	0/10
300	15/24	14/24

MN formation in phenol-treated mice

Dose in mg/kg bw (sex)	Post exposure interval in hours	MN per/1000 PCE
		Unsupported	Supported
0 (m)	24	2.1 ± 1.8	5.0 ± 3.1
300 (m)	24	10.8 ± 8.5*	9.3 ± 4.4*
0 (f)	24	2.5 ± 2.0	3.6 ± 1.0
300 (f)	24	11.3 ± 9.3*	20.6 ± 7.4*
0 (m)	48	1.1 ± 0.4	3.2 ± 2.0
300 (m)	48	18.3 ± 1.8*	3.0 ± 2.4
0 (f)	48	2.4 ± 1.4	1.8 ±1.2
300 (f)	48	17.8 ± 14.3*	6.1 ± 3.1
Positive control	24	79.9 ± 20.1	-

*: alpha <= 0.05

Applicant's summary and conclusion

Conclusions:

Interpretation of results (migrated information): other: threshold dependent chromosome mutagenic activity
Thermoregulatory support prevented the induction of mirconuclei measured 48 h after application of phenol. Initial sustained hypothermia in phenol-treated animals was not prevented by thermoregulatory support and likely accounts for the increase in micronuclei at 24 h.
Authors comment: Distinguishing the role of hypothermia in the induction of micronuclei from direct action of phenol/metabolites with the cellular target(s) by providing thermoregulatory support is unlikely.

Executive summary:

Study is comparable to OECD 474 with acceptable restrictions (party limited documentation).

The authors evaluated the effects of thermoregulatory support on the induction of micronuclei in the bone marrow of phenol-treated mice. Doses of phenol that did not induce substantial hypothermia in mice were not associated with an increase frequency of micronuclei ( see Spencer et al., 2007, in this Section). It should be shown in this study that the prevention of hypothermia will inhibit the induction of micronuclei in the bone marrow of phenol-treated mice. Mice housed in standard environment or under thermoregulatory support conditions received a single injection of i.p. 0 or 300 mg/kg bw and bone marrow was prepared 24 or 48 h after application. In unsupported males and females the body temperature (BT) decreased to ca. 31.5°C 24 h after application; BT of 29°C in males and ca. 30.5 in females were measured 48 h after application. Only a slight decrease in BT of ca. 1°C was detected at the same time in male and female mice using thermoregulative support. The mortality rate was increased in supported mice. Thermoregulatory support did not prevent MN induction in phenol-treated mice at 24 h post-dosing but at 48 h post-dosing. BT measurement at 0, 24 and 48 h did not allow full characterization of BT profiles. Therefore, additional experiments were conducted on the effectiveness of thermoregulatory support (BT measured every 5 minutes). Also in mice receiving thermoregulatory support a dose of 300 mg/kg bw resulted in an initial decrease in BT (min. 32.5°C) reaching average BT again after approx. 3 h.

Conclusion: Thermoregulatory support prevented the induction of mirconuclei measured 48 h after application of phenol. Initial sustained hypothermia in phenol-treated animals was not prevented by thermoregulatory support and likely accounts for the increase in micronuclei at 24 h.