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EC number: 270-695-5 | CAS number: 68476-55-1
- Life Cycle description
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- Endpoint summary
- Appearance / physical state / colour
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- Additional physico-chemical information
- Additional physico-chemical properties of nanomaterials
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- Endpoint summary
- Stability
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- Environmental data
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- Ecotoxicological Summary
- Aquatic toxicity
- Endpoint summary
- Short-term toxicity to fish
- Long-term toxicity to fish
- Short-term toxicity to aquatic invertebrates
- Long-term toxicity to aquatic invertebrates
- Toxicity to aquatic algae and cyanobacteria
- Toxicity to aquatic plants other than algae
- Toxicity to microorganisms
- Endocrine disrupter testing in aquatic vertebrates – in vivo
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- Toxicological Summary
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- Specific investigations
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- Additional toxicological data

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:
- migrated information: read-across from supporting substance (structural analogue or surrogate)
- Adequacy of study:
- key study
- Reliability:
- 2 (reliable with restrictions)
- Rationale for reliability incl. deficiencies:
- other: GLP status unknown, near guideline study, published in peer reviewed literature, adequate for assessment.
Data source
Reference
- Reference Type:
- publication
- Title:
- Chloroprene and isoprene: cytogenetic studies in mice
- Author:
- Tice RR et al
- Year:
- 1 988
- Bibliographic source:
- Mutagenesis 3 (2), 141-146
Materials and methods
Test guideline
- Qualifier:
- according to guideline
- Guideline:
- OECD Guideline 474 (Mammalian Erythrocyte Micronucleus Test)
- GLP compliance:
- not specified
- Type of assay:
- micronucleus assay
Test material
- Reference substance name:
- Isoprene
- EC Number:
- 201-143-3
- EC Name:
- Isoprene
- Cas Number:
- 78-79-5
- Molecular formula:
- C5H8
- IUPAC Name:
- 2-methylbuta-1,3-diene
- Reference substance name:
- 2-methyl-1,3-butadiene
- IUPAC Name:
- 2-methyl-1,3-butadiene
- Details on test material:
- Purity > 98% (Goodyear Tire and Rubber Co., Akron, OH, USA)
Constituent 1
Constituent 2
Test animals
- Species:
- mouse
- Strain:
- B6C3F1
- Sex:
- male
- Details on test animals or test system and environmental conditions:
- TEST ANIMALS
- Source: National Toxicology Program's production colonies (Simonsen Laboratories, Gilroy, CA, USA)
- Age at study initiation: 5-7 week
- Housing: Individually in polycarbonate cages for the first 5 days and in stainless steel racks in Hazleton 2000 inhalation chambers thereafter.
- Diet: ad libitum (except during exposure)
- Water: ad libitum
- Acclimation period: 2 weeks
ENVIRONMENTAL CONDITIONS
- Temperature: 20-24°C
- Humidity: 50 ± 15%
- Air changes (per hr): no data
- Photoperiod: 12(hrs dark / 12hrs light
IN-LIFE DATES: not reported
Administration / exposure
- Route of administration:
- inhalation
- Vehicle:
- Vehicle(s)/solvent(s) used: air
- Details on exposure:
- TYPE OF INHALATION EXPOSURE: whole body
TEST ATMOSPHERE
- Brief description of analytical method used: The chamber concentration of isoprene was monitored at 30 min intervals by gas chromatography to a detection limit of 0.02 ppm. - Duration of treatment / exposure:
- 6 hours/day for 12 days
- Frequency of treatment:
- 3 exposure days, followed by 2 non-exposure days, followed by 5 exposure days, followed by 2 non-exposure days, followed by 4 exposure days.
Doses / concentrations
- Remarks:
- Doses / Concentrations:
0, 438, 1750, 7000 ppm
Basis:
nominal conc.
- No. of animals per sex per dose:
- 15
- Control animals:
- yes, sham-exposed
Examinations
- Statistics:
- The number of micronucleated erythrocytes (MN) were summed across animals within each group and analyzed for increasing trend by a one-tailed trend test (p<0.05). For data exhibiting a significant trend, pairwise comparisons between each exposure group and the concurrent control were performed using a one-tailed Pearson Chi square test to determine the minimal effective dose.
Results and discussion
Test results
- Sex:
- male
- Genotoxicity:
- positive
Any other information on results incl. tables
NOAEL
(NOEL): <
438 ppm
LOAEL (LOEL): 438
ppm
Exposure to isoprene for 6 h/day for 12 days induced a statistically
significant increase in the frequency of MN-PCEs and NCEs in male mice
at all exposure levels tested. The
frequencies of MN-PCEs were 2.00, 12.00, 15.60 and 16.93 at 0, 438,
1750, and 7000 ppm. The responses at the 1750 and 7000 ppm levels both
were greater than the 438 ppm level, but not statistically different
from each other. There
also was a dose-related decrease in the percentage of PCEs, a measure of
the rate erythropoiesis (3.91, 3.00, 2.87, and 1.64 at 0, 438, 1750 and
7000 ppm). There
were no significant clinical signs or mortality.
Applicant's summary and conclusion
- Conclusions:
- Interpretation of results (migrated information): positive
Isoprene was found to be genotoxic to mouse bone marrow in vivo by inducing increased MN in the peripheral blood of male mice. Suppression of erythropoiesis was suggested by decreased percentage of PCEs. - Executive summary:
Groups of 15 male B6C3F1 mice were exposed for 6 hour/day for 12 days to 0, 438, 1750 and 7000 ppm isoprene. Exposure to isoprene induced significant increases at all concentrations in the levels of micronucleated polychromatic erythrocytes (PCE) and of micronucleated normochromoatic erythrocytes in peripheral blood. In addition, a significant lengthening of the bone marrow average generation time and a significant decrease in the percentage of circulating PCE was detected. The dose-response curve for micronuclei induction was non-linear, appearing to saturate at 1750 ppm.
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