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Table 1 (continued):
Epidemiological Studies of Exposure to Diesel Exhaust and Lung Cancer Studies
Among Transport (i.e. bus) and Equipment Workers
Reference
Study Design,
Population, and
Exposures
Cases
or
deaths
Effect
Measure
Confidence
Interval a or
P-Value
Comments
Wong et al.
1985
USA
Cohort
Total
By Duration
20 years
All retired members
Normal retired
members
309
10
25
53
58
163
155
86
SMR
0.99
0.45
0.75
1.08
1.02
1.07
1.64*
1.30**
0.88-1.10
N.S.
N.S.
N.S.
N.S.
p = 0.05
p < 0.01
p < 0.05
Cohort consisted of 34,156 male members of a
heavy construction equipment operators union for at
least one year from 1964 through 1978. Mortality
experience was compared with that of the US
white male population. Partial work history was
available for some cohort members through the
union. A random sample of union members was
surveyed to determine smoking habits, and no
significant difference between members and the
general population was found. Work groups
evaluated were considered to have high exposure to
diesel exhaust (scraper operator, bulldozer operator,
backhoe operator and loader operator) or low
exposure (mechanical maintenance workers and
engineers). Overall mortality in the cohort was less
than that in the U.S. male population (SMR 0.81,
95% C.I. 0.79-0.84). Workers were also categorized
by job title and potential exposure, but no significant
risks were observed. Analysis of retirees found an
excess risk for lung cancer* and emphysema.
*Includes also retirements due to ill health.
*Normal retirees are those workers retired at or over
65 and early retirees who reached 65.
Edling et al.
1987
Sweden
Cohort
Bus company
employees
Bus drivers
Bus garage workers
Clerks
6
5
1
0
SMR
0.67
0.69
Not
presented
Cohort consisted of 694 bus garage employees
followed from 1951 through 1983. Men were divided
into three exposure categories (clerks, bus drivers and
bus garage workers). Clerks were assumed to have
had the lowest exposure to diesel exhaust and bus
garage workers the highest.
Authors stated that the power of the study to detect
specific cancers was limited. No data on smoking.
Netterstrom
1988
Denmark
Cohort
Bus drivers 15
SMR
0.87 0.48-1.43
Cohort of 2,465 Danish bus drivers from three
companies during the period 1978 to 1984. Cases
were identified through death and cancer registries.
Death rates were compared with national rates. No
data on smoking were available. Mean value for
employment duration among the lung cancer cases
was 30 years
a 95% Confidence intervals unless noted. N.S.= Not significant. No confidence intervals or p-values
reported in original study. DE = Diesel Exhaust, OR = Odds Ratio, RR = Relative Risk, SIR =
Standardized Incidence Ratio, SMR = Standardized Mortality Ratio
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