(VCCEP) Tier 1 Pilot Submission for BENZENE - Tera

dose response was demonstrated in this study for either cumulative exposure or frequency of
peak exposures.
Canadian petroleum workers were studied in a retrospective mortality study by Schnatter et al.
(1993). Consistent with other refinery and petroleum worker studies, there was no significantly
elevated increase in AML reported, nor evidence of a dose-response between leukemia risk and
any measure of benzene exposure (Schnatter et al., 1996a,c). However, an elevated SMR of
3.87 (95% CI; 1.06–9.92) was reported for AML for tank truck drivers employed for more than
1 year (Schnatter et al., 1993). Cumulative exposures of benzene in this cohort were estimated
to be as high as ~220 ppm-years (Schnatter et al., 1996a,c).
Wen et al. (1983) evaluated 16,880 employees who worked at the Port Arthur, Texas, refinery
from 1937 through 1978. An SMR for all leukemia combined was reported to be 1.14 (no
statistically significant increased risk).
One small study by McCraw et al. (1985) reported a statistically elevated SMR for AML in
refinery workers. A second small case-control study by Sathiakumar et al. (1995) also reported
an elevated OR for AML in oil and gas production workers, although no exposure data were
included. However, in the Sathiakumar study, an elevated SMR was not seen in refinery
workers. In addition to the studies described in this section, multiple independent refinery and
petrochemical studies have been conducted and consistently report a non-elevated SMR for
AML or leukemia (Theriault et al., 1979; Naumann et al., 1993; Raabe et al., 1998; Marsh et al.,
1991; Wong et al., 1986; Dagg et al., 1992; Satin et al., 1996; Thomas et al., 1982; Austin et al.,
1986; Divine et al., 1987; Austin et al., 1983). Taken collectively, the scientific literature is
consistent in its demonstration that refinery workers do not have an elevated risk of developing
AML, and suggests that a threshold exists for AML induction by benzene exposure.
6.1.11 Service Station Attendants and Vehicle Mechanic Epidemiology
Lynge et al. (1997) conducted a cancer incidence study in 19,000 service station workers
exposed frequently to benzene-containing materials (gasoline) and found no increased risk of
developing AML. This investigation was carried out in various Scandinavian countries and
included service station attendants employed prior to 1972. There were no self-service stations
in existence at this time; therefore, all gasoline was pumped by the attendants (increasing their
potential for exposure). This cohort was exposed to average benzene levels estimated to be
~0.15–0.3 ppm. The benzene content in European gasoline at that time was between 2% and
10%, with an average value of at least 5%.
Schwartz (1987) conducted a small proportionality mortality ratio (PMR) analysis of deaths
among gasoline service attendants and automobile mechanics. There was no elevation in
mechanics and a slight increase in gasoline workers for all leukemias combined (ICD 204-207).
The problems associated with PMR analysis are well documented. Lagorio et al. (1994) also
conducted a small mortality study of filling station attendants and reported no increase in total
leukemias. Lindquist et al. (1991) reported an elevated risk in all acute leukemias (including
ALL) to professional drivers exposed to gasoline and diesel. However, other authors observed
no relationship between leukemia risk and occupational exposure as a professional driver
(Lindquist et al., 1991; Lagorio et al., 1994; Wong et al., 1999, 1993).
Another large, independent study of petroleum distribution workers with potential exposures to
gasoline found no increase in total leukemia (SMR = 0.89) and no statistically significant
increase in AML (SMR = 1.50; 95% CI 0.80–2.57 (Wong et al., 1993). In a nested case-control
Benzene VCCEP Submission
March 2006
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