Appendix D - Dossier (PDF) - Tera

date: 20–JUL–2005
5. Toxicity Substance ID: 71–43–2
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ppm). As part of our R&D program for evaluation of cancer
predictive values of biomarkers for genotoxic effects of
occupational exposure to chemical human carcinogens, we
performed cytogenetic studies in 114 Bulgarian workers from
4 different chemical plants, chronically exposed to
benzene,
and in a control group of 68 persons. Study subjects were
divided into 4 groups: controls and subjects exposed to
1.1–1.7 ppm; 2.3–4.7 ppm and 7–24 ppm benzene. The
cytogenetic biomarkers studied in peripheral lymphocytes
(Ly) included chromosome aberrations (CA) and micronuclei,
analyzed by the cytokinesis block (CB) MN assay. A
significant 3 fold increase in the frequency of the
percentage aberrant cells was found in workers of the
lowest
exposure group only (2.3 ± 1.7 vs 0.67 ± 0.7 in controls)
with an "exposure response" relationship. Age, smoking, and
duration of exposure had no effect on the levels of CA. A
highly significant 4–5 fold increase in the frequency of
MN–binucleated Ly (BN–Ly) and MN in BN–Ly was found in all
exposure groups. This increase was significantly correlated
with age and duration of exposure in the medium exposure
group. Based on the cytogenetic damage revealed in workers
exposed to low levels of benzene (1.1–1.7 ppm) an increased
carcinogenic risk was predicted and lowering of the
national
occupational exposure standard for benzene to 0.31 ppm was
proposed.
Cytogenetic biomarkers used in occupational surveillance
programs: A report from ongoing Bulgarian cytogenic
studies
of workers exposed to benzene.
Source: EXXON Biomedical Sciences East Millstone, NJ
Reliability: (4) not assignable
03–NOV–1998 (784)
Remark: ABSTRACT: The purpose of the National Exposure Registry is
to assess the long–term health consequences to a general
population from long–term, low–level exposures to specific
substances in the environment. This study investigates the
health outcomes of 1,143 persons (1,127 living, 16
deceased)
living in south central Texas who had documented
environmental exposure to benzene (up to 66ppb)in tap
water.
As with all subregistries, face–to–face interviews were
used
to collect self–reported information for 25 general health
status questions. Using computer–assisted telephone
interviewing, the same health questions were asked 1 year
(Follow–up 1, F1) and 2 years later (Followup 2, F2). The
health outcome rates for Baseline and Followup 1 and 2 data
collections for the Benzene Subregistry were compared with
national norms, that is, the National Health Interview
Survey (NHIS) rates. For at least one of the three
reporting
Appendix D: Benzene SIDS Dossier
– 714/957 –