Appendix D - Dossier (PDF) - Tera

date: 20–JUL–2005
5. Toxicity Substance ID: 71–43–2
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publication.
Source: Deutsche Shell Chemie GmbH Eschborn
06–JAN–1997 (797)
Remark: This is a report from the Commission of the European
Communities which develops a scientifically based
occupational exposure limit for benzene. Presented in this
report are preliminary results of an unpublished study of
the influence of low level benzene exposures on the blood
cells (Van Damme et al., 1991). The study examined all
employees at a petrochemical plant who were working at the
end of 1988 and had at least 5 haematological examinations
during 1967–1988. There were 484 employees with a total of
17,404 blood samples. Based on exposure data from
1978–1988, more of the workers were exposed to benzene
levels higher than 6.4 mg/m3 (2 ppm) since 1971. The
results of this study suggest an increased prevalence of
leucopenia (defined as < 4000 cells/uL) for exposures of
0.64 to 1.92 mg/m3 (0.2 to 0.6 ppm) which is well below
no–effect level estimates of 64 mg/m3 (20 ppm) for WBC
effects reported by other investigators, (Kipen et al.,
1989; Townsend et al., 1978; Fishbeck et al., 1978; Tsai et
al., 1983; Collins et al., 1991). However, this study has
not appeared in the published literature and it conflicts
with the other published studies cited above.
Source: Deutsche Shell Chemie GmbH Eschborn
06–JAN–1997 (179)
Remark: This ia a letter–to–the–editor which suggests that Kipen’s
et al. (1991) conclusions regarding decreasing benzene
exposures and increasing WBC and RBC counts were flawed
because pre–employment data showed a similar increase in
WBCand RBC counts during 1940–48. Hornung et al.’s (1991)
regression analysis of pre–employment counts predicted an
increase of 16 counts/month compared to the 33 counts/month
observed in the Kipen et al. (1988) data. Hornung et al.
(1991) commented that a plot of monthly RBC and WBC counts
showed an upward shift between July and August, 1947.
WhileHornung et al. (1991) do not offer a reason for the
shift, they call into question a benzene effect on the
counts as reported by Kipen. Kipen et al. (1991) replied
that they thought the trend in pre–employment WBC counts
shown by Hornung et al. (1991) might have a low r2 (which
is
a measure of the proportion of variance explained) value
(theysuggested 0.04), while r2 for WBC counts found in the
Kipen et al. (1988) study was 0.88. Kipen et al. (1991)
argued that the negligible trend reported by Hornung et al.
(1991) actually verified the contention that the decrease
in
WBC counts was not the result of gradual or sudden changes
in laboratory techniques over the nine year span.
Source: Deutsche Shell Chemie GmbH Eschborn
06–JAN–1997 (523)
Appendix D: Benzene SIDS Dossier
– 701/957 –