Appendix D - Dossier (PDF) - Tera

date: 20–JUL–2005
5. Toxicity Substance ID: 71–43–2
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an association between lymphocyte hyperploidy and urinary
excretion of benzene metabolites was present in Chinese
workers whereas no association was present in the Estonian
group. A subset of Chinese workers also showed an
association between increased hyperploidy and airborne
benzene exposures > 38 mg/m3 benzene (8–hr TWA).
04–MAR–2003 (319)
Type: Cytogenetic assay
Species: mouse Sex: male
Strain: CD–1
Route of admin.: inhalation
Exposure period: 6 weeks
Doses: o.1 or 1.0 ppm
Result: ambiguous
Method: other
Year: 1988
GLP: no
Test substance: no data
Remark: chromosomal aberration test with lung macrophages
Source: German rapporteur
Flag: Risk Assessment
21–AUG–2000 (57)
Type: other: role of topoisomerase II in benzene–related DNA damage
Method: IN VITRO TOPOISOMERASE INHIBITION ASSAYS
Inhibition of topoisomerase II was followed using gel
electrophoresis to visualise monomers released from isolated
mitochondrial DNA after incubation with benzene metabolites
(commercial kit: TopoGEN). Experiments were performed in
duplicate, in the presence and in the absence of a horse
radish peroxidase system (HRPS; used to activate
metabolites).
Appendix D: Benzene SIDS Dossier
BINDING STUDIES USING ISOLATED TOPOISOMERASE II
[14C]–Phenol was converted to reactive metabolites using a
horse radish peroxidase system and mixed with topoisomerase
II, in the absence or presence of additional glutathione.
Topoisomerase proteins containing bound radioactivity were
separated using SDS–polyacrylamide gel electrophoresis
(SDS–PAGE) and accelerator mass spectrometry (AMS) used to
characterise bound [14C]phenol equivalents.
STUDIES USING HUMAN HL–60 CELLS
HL–60 cells (from a human promyelocytic leukemic cell line)
were incubated with various concentrations of benzene
metabolites and cell viability followed for up to 48 hr. The
results were used to estimate doses at which topoisomerase
II inhibition would be likely to occur. In a subsequent
series of experiments, HL–60 cells were incubated with
biphenol (500 uM), hydroquinone (50 uM), catechol (500 uM)
or benzenetriol (100 uM) and HRPS, and topoisomerase II
extracted and its activity assayed using a commercial kit.
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