Registration Dossier

Toxicological information

Genetic toxicity: in vivo

Currently viewing:

Administrative data

Endpoint:
in vivo mammalian somatic cell study: cytogenicity / erythrocyte micronucleus
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
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: GLP compliant (except for minor deviations listed below), guideline study, available as unpublished report, no restrictions, fully adequate for assessment.

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2009
Report Date:
2009

Materials and methods

Test guidelineopen allclose all
Qualifier:
according to
Guideline:
OECD Guideline 474 (Mammalian Erythrocyte Micronucleus Test)
Deviations:
yes
Remarks:
The identity and stability of test material was not in compliance with GLP regulations. The lot number was not available. The identity, strength, purity, composition and purity of positive control was not performed at HLS.
Qualifier:
according to
Guideline:
EPA OPPTS 870.5395 (In Vivo Mammalian Cytogenetics Tests: Erythrocyte Micronucleus Assay)
Principles of method if other than guideline:
A 13-week whole-body inhalation toxicity study in rats with neurotoxicity assessments and in vivo genotoxicity assessments
GLP compliance:
yes
Type of assay:
micronucleus assay

Test material

Reference
Name:
Unnamed
Type:
Constituent
Details on test material:
- Name of test material (as cited in study report): liquefied petroleum gas (LPG)
- Substance type: industrial gas
- Supplier: ChevronTexaco Energy Research & Technology Company, 100 Chevron Way, Richmond, CA 94802, USA
- Physical state: colourless gas or liquid in pressurized cylinders
- Analytical purity: 100% LPG
- Lot/batch No.: 120701-01
- Composition of test material, percentage of components (weight %): methane 0.012%, ethane 1.809%, propane & propylene 93.513%, n-butane 2.854%, n-pentane 0.064%, isobutane 1.246%, neopentane 0.003%, isopentane 0.404%, 2,3-dimethylbutane 0.006%, cyclopentane <0.001%, isobutene 0.038%, 1,3-butadiene <0.001%, t-2-butene 0.009%, c-2-butene 0.007%, 3-methyl-1-butene 0.004%, 1-pentene 0.014%, 2-methyl-1-butene 0.005%, t-2-pentene 0.003%, c-2-pentene 0.003%, 2-methyl-2-butene 0.005%, benzene <0.001%
- Expiration date of the lot/batch: 31 December 2007
- Storage condition of test material: Ambient conditions in an outside solvent shed except when in use in the inhalation laboratory.


Test animals

Species:
rat
Strain:
other: Sprague-Dawley CD
Sex:
male/female
Details on test animals and environmental conditions:
TEST ANIMALS
- Species: Albino rats (Outbred) VAF/Plus®, Sprague-Dawley derived (CD®), Crl:CD®(SD)IGS BR
- Source: Charles River Laboratories, Kingston, New York 12484, USA
- Age at study initiation: Approximately 8 weeks
- Weight at study initiation: Males mean 280 g (range 243-308 g); females mean 209.1 g (range 187-231 g)
- Fasting period before study: None
- Housing: Individually in stainless steel suspended cages with wire mesh floors and fronts.
- Diet: Certified Rodent diet No 5002 (PMI Nutrition International, St Louis, Missouri, USA) ad libitum
- Water: Municipal water ad libitum
- Acclimation period: Approximately 2 weeks

ENVIRONMENTAL CONDITIONS
- Temperature: 17-25°C
- Humidity: 22-99%
- Air changes (per hr): Not reported
- Photoperiod: 12 hrs dark / 12 hrs light

IN-LIFE DATES: From: 20 April 2005 To: 27 July 2005

Administration / exposure

Route of administration:
inhalation: gas
Vehicle:
- Vehicle(s)/solvent(s) used: air
Details on exposure:
GENERATION OF TEST ATMOSPHERE / CHAMBER DESCRIPTION
- Exposure apparatus: Stainless steel and glass whole body exposure chambers with a volume of approximately 1000 L
- Method of holding animals in test chamber: Individually housed in stainless steel, wire mesh cages within the exposure chamber, with the placement of animals in chambers rotated weekly to ensure uniform exposure.
- Generation: Pre-study trials had evaluated the optimal set of conditions and equipment that generated a stable and uniform atmosphere at the target exposure levels. Test substance flowed from cylinder into a copper tubing coil, maintained in a warm water bath. From the coil the test substance flowed through a metering valve to a mass flowmeter and then via tubing to the turret of the exposure chamber, where it was mixed with room air.
- Temperature, humidity in exposure chamber: 19-28°C, 22-61%
- Air flow rate: Operated at a minimum rate of 203 L/min. Final airflow set to provide at least one air change /5 mins (12/hour) and a T99 equilibrium time of at most 23 mins.
- Oxygen level: at least 19%
- Animal loading factor: below 5%
- Method of particle size determination: yes. Samples drawn for 20 secs at a flow rate of 5 L/min. MMAD, GSM and total mass concentration were calculated.
- Treatment of exhaust air: coarse filter, a HEPA filter and activated charcoal

TEST ATMOSPHERE
- Brief description of analytical method used: Infrared spectrophotometer (IR) 4 times per chamber per day. Gas chromatography (GC) used to characterise at least 5 major components (comprising at least 90% by weight of test substance) once/week/chamber to show test substance stability and comparison between neat test substance and test atmospheres.
- Samples taken from breathing zone: yes
Duration of treatment / exposure:
13 weeks
Frequency of treatment:
6 hours/day, 5 days/week
Post exposure period:
Approximately 18-24 hours
Doses / concentrationsopen allclose all
Remarks:
Doses / Concentrations:
0, 1000, 5000, 10000 ppm
Basis:
other: target conc.
Remarks:
Doses / Concentrations:
0.0 ± 0.0, 1019 ± 58, 5009 ± 174, 9996 ± 261 ppm
Basis:
analytical conc.
No. of animals per sex per dose:
5/sex/group of the main study animals were used for micronucleus assessment together with 5/sex/group as positive controls
Control animals:
yes, sham-exposed
Positive control(s):
cyclophosphamide monohydrate (CP)
- Route of administration: intraperitonael injection
- Doses / concentrations: 40 mg/kg bw
- supplied by: Sigma Aldrich, Inc., 3050 Spruce St., St Louis, MO 63103, USA

Examinations

Tissues and cell types examined:
Bone marrow from the right femur
Details of tissue and slide preparation:
5 rats/sex/group, were exposed to liquified petroleum gas by inhalation at exposure levels of 0, 1000, 5000 or 10000 ppm for a 13 week (5 days per week) exposure period. A group of non-exposed (5/sex) positive control animals (40 mg/kg cyclophosphamide, injected ip with a 4.0 mg/mL solution @ 10 mg/kg, within 24 hours prior to sacrifice) were also dosed. The test animals were sacrificed under carbon dioxide anaesthesia. The time
between last exposure and tissue harvest was approximately 18 to 24 hours. The right femurs were removed and sampled. Unstained slides were prepared and stained (Acridine orange) and evaluated using a fluorescent microscope for determination of micronucleus response.
Evaluation criteria:
Incidences of micronucleated immature erythrocytes were calculated.
Statistics:
Results obtained for each treatment group were compared with control results using non-parametric statistical methods with sexes combined. For incidences of micronucleated immature erythrocytes, exact one-sided p-values were calculated by permutation. Comparison of several dose levels was made with the concurrent control using the Linear by Linear Association test for trend in a step-down fashion if significance is detected. For inter-group comparisons a straightforward permutation test was used. For assessment of effects on the proportion of immature erythrocytes, equivalent permutation tests based on rank scores were used i.e. exact versions of Wilcoxon's sum of ranks test and Jonckheere's test for trend.

Results and discussion

Test results
Sex:
male/female
Genotoxicity:
negative
Toxicity:
not specified
Negative controls validity:
valid
Positive controls validity:
valid
Additional information on results:
After 13 weeks of exposure, there were no treatment-related differences in micronucleus incidence.

Applicant's summary and conclusion

Conclusions:
Interpretation of results (migrated information): negative
After 13 weeks of exposure of rats to liquified petroleum gas, there were no treatment-related differences in micronucleus incidence at concentrations up to 10000 ppm, compared to the air control animals. The no observed adverse effect concentration (NOAEC) was 10000 ppm.
Executive summary:

This study was designed to assess the potential inhalation toxicity of liquified petroleum gas (LPG) when administered via whole-body exposures to rats for 13 weeks. The assessment included routine toxicology parameters as well as detailed evaluations of genotoxicity parameters.

Sprague-Dawley CD® rats were exposed for six hours per day to 0 (air control), 1000, 5000 or 10000 ppm of LPG for 5 days per week for 13 consecutive weeks (highest exposure concentration was selected for safety reasons and approximated 50% of the lower explosive limit).

At the end of the treatment period, all animals were euthanized and necropsied and the incidences of micronucleated immature erythrocytes were calculated in 5 males & females per dose concentration.

After 13 weeks of exposure of rats to liquified petroleum gas, there were no treatment-related differences in micronucleus incidence at concentrations up to 10000 ppm, compared to the air control animals. The no observed adverse effect concentration (NOAEC) was 10000 ppm.