Below are the first 10 and last 10 pages of uncorrected machine-read text (when available) of this chapter, followed by the top 30 algorithmically extracted key phrases from the chapter as a whole.
Intended to provide our own search engines and external engines with highly rich, chapter-representative searchable text on the opening pages of each chapter.
Because it is UNCORRECTED material, please consider the following text as a useful but insufficient proxy for the authoritative book pages.
Do not use for reproduction, copying, pasting, or reading; exclusively for search engines.
OCR for page 12
13
ARTICLE SUMMARIES*
Reviewer: Susan Buchanan
Title: Bruske-Hohlfeld, I., Mohner, M., Ahrens, W., Pohlabeln, H., Heinrich, J., Kreuzer, M.,
Jockel, K.H., and Wichmann, H.E. "Lung cancer risk in male workers occupationally
exposed to diesel motor emissions in Germany." Am J Ind Med. 1999 Oct;36(4):40514.
Abstract: Background: Although in several epidemiological studies exposure to diesel motor emis-
sions (DME) shows an elevated lung cancer risk, it is still controversial whether DME is a
human carcinogen. Methods: In a pooled analysis of two case-control studies on lung can-
cer in Germany a total of 3,498 male cases with histologically or cytologically ascertained
lung cancer and 3,541 male population controls were included. Information about lifelong
occupational and smoking history was obtained by questionnaire. Drivers of lorries, buses,
taxies, diesel locomotives and forklift trucks, bulldozers, graders, excavators, and tractors,
were considered as exposed to DME and their cumulative exposure was estimated. All odds
ratios were adjusted for smoking and asbestos exposure. Results: The evaluation of lung
cancer risk for all jobs with DME-exposure combined showed an odds ratio of OR = 1.43
(95%-CI: 1.231.67). Most pronounced was the increase in lung cancer risk in heavy equip-
ment operators (OR = 2.31 95%-CI: 1.443.70). The risk of tractor drivers increased with
length of employment and reached statistical significance for exposures longer than 30
years (OR = 6.81, 95%-CI: 1.1739.51). The group of professional drivers (e.g., trucks,
buses, and taxies), showed an increased risk only in West Germany (OR = 1.44, 95%-CI:
1. 181.76), but not in East Germany (OR = 0.83, 95%-CI: 0.601.14). DME-exposure in
other traffic-related jobs (e.g., diesel engine locomotive drivers, switchmen, forklift opera-
tors) was associated with an odds ratio of OR = 1.53 (95%-CI: 1.042.24). Conclusions: The
study provides further evidence that occupational exposure to diesel motor emissions is
associated with an increased lung cancer risk.
Methodology: Two case-control studies were pooled for a joint analysis: all patients born in Germany after
1913 and diagnosed with lung cancer between 1988 and 1993 were used in one of the stud-
ies. The other study evaluated residents in 4 regions of Germany who were diagnosed with
lung cancer in 1994. Controls for both studies were selected at random from municipal reg-
istries. A standardized questionnaire was performed in face-to-face interviews to obtain
demographic information and job histories. Exposure to diesel motor exhaust was charac-
terized by years of exposure after evaluating job task descriptions. Lung cancer risk was
calculated according to the cumulated exposure and with respect to job group.
Scope of Work: To estimate lung cancer risk in workers occupationally exposed to diesel motor exhaust.
Sample Size: 3,498 cases and 3,541 controls
Industry Sector: Professional drivers
Major Limitations: Exposure was estimated based on participants' self-reported job task history.
Findings Directly Related Working Conditions (Environmental except sleeper berth)
to HOS (include page
references): Odds ratios were adjusted for smoking and asbestos exposure and showed that professional
drivers had significantly higher rates of lung cancer. Workers of any category who were
exposed to diesel motor exhaust for between 20 and 30 years had significantly higher rates of
lung cancer. Risk increased with increased duration of exposure. And compared with workers
who had never been exposed, those who were exposed had a 43% higher rate of lung cancer.
*Summaries are presented in the order submitted by the researchers.
OCR for page 13
14
"Our study results show an increasing lung cancer risk for professional drivers, adjusted for
smoking and asbestos exposure (Table III), which is similar to the results of most other epi-
demiological studies." (p. 412)
Reviewer's Notes: Though retrospective with estimated exposures, this study, with a large sample population,
showed significant associations between lung cancer and both exposure to diesel exhaust
and a dose-response.
OCR for page 14
15
Reviewer: Susan Buchanan
Title: Colt, J.S., Baris, D., Stewart, P., Schned, A.R., Heaney, J.A., Mott, L.A., Silverman, D.,
and Karagas, M. "Occupation and bladder cancer risk in a population-based case-control
study in New Hampshire." Cancer Causes Control. 2004 Oct;15(8):75969.
Abstract: Objective: To identify occupations with excess bladder cancer risk in New Hampshire,
where bladder cancer mortality rates have been elevated for decades. Methods: Lifetime
occupational histories were obtained from interviews with 424 cases and 645 controls in a
population-based case-control study. Unconditional logistic regression models were used
to estimate odds ratios (OR) and 95% confidence intervals (CI) for each occupation,
adjusted for age and smoking. Analyses by duration of employment were carried out and
interactions with smoking were examined. Results: Male tractor-trailer truck drivers had an
elevated risk for bladder cancer (OR = 2.4, CI = 1.44.1), with a significant positive trend
in risk with increasing duration of employment (P (trend) = 0.0003). Male metal/plastic pro-
cessing machine operators also had a significant excess (OR = 4.9, CI = 1.615.1), attrib-
utable mainly to molding/casting machine operators (OR = 16.6, CI = 2.1131). Elevated
risk was also observed for male fabricators, assemblers, and hand workers (OR = 1.8, CI =
1.03.4). Women in certain sales occupations (sales clerks, counter clerks, and cashiers)
had a significant excess risk (OR = 2.2, CI = 1.33.9) and a significant trend with duration
of employment (P (trend) = 0.016), as did female health service workers (OR = 4.1, CI =
1.610.7; P (trend) = 0.014). There was a positive interaction between smoking and
employment as a health service worker (p = 0.036). Conclusions: These findings are gen-
erally consistent with previous studies. Elevated risks for male molding/casting machine
operators, female sales workers, and female health service workers, especially those with a
history of smoking, require further investigation.
Methodology: This study is part of a larger population-based case-control study evaluating risk factors for
bladder cancer in New Hampshire. This paper reports on the occupational data. New Hamp-
shire residents diagnosed with bladder cancer between July 1994 and June 1998 were iden-
tified from the state cancer registry. Controls were selected from the Department of Trans-
portation population lists and matched for age and gender. Participants underwent a detailed
in-home interview and information on job history was collected. Odds ratios were calcu-
lated adjusting for age and smoking status.
Scope of Work: To identify high-risk occupations in New Hampshire, where bladder cancer mortality rates
have been elevated for decades, and to re-examine occupations that have been found to be
associated with bladder cancer in previous studies.
Sample Size: 424 cases, 645 controls
Industry Sector: Tractor-trailer truck drivers
Major Limitations: This study excludes cases which did not survive to the time of the interview, such as those
with rapidly growing or late diagnosed cancers (e.g., most severe cases). This would be a
positive bias if another factor produced a more aggressive picture than driving exposure and
a negative bias if the reverse was true. Exposure duration had only 2 categories: employed
as truck driver <5 years or 5 years.
Findings Directly Related Driver Health (General)
to HOS (include page
references): Tractor-trailer truck drivers had an excess bladder cancer odds ratio of 2.3, which was sig-
nificant. See Table 2. There was a positive trend of increasing risk with duration of employ-
ment. See Table 3. Duration of employment was categorized by <5 year or 5 years. "In
OCR for page 15
16
our study, bladder cancer risk was higher among men who drove trucks typically fueled by
diesel (tractor-trailers) than among drivers of other types of trucks, and there was no
increase for taxicab or bus drivers. Thus, our study supports the possibility of diesel expo-
sure as the putative factor." (p. 765)
Reviewer's Notes: This study was chosen from several that have shown significant odds ratios for bladder can-
cer in truck drivers (see secondary references). Although the characterization of exposure
was limited, it was the most recent study published on this issue. It showed both a positive
association between truck driving and bladder cancer and a dose-response trend between
drivers exposed 5 years compared with those with exposure for <5 years.
OCR for page 16
17
Primary Reviewer: Susan Buchanan
Complete Title: Guo, J., Kauppinen, T., Kyyronen, P., Heikkila, P., Lindbohm, M.L., and Pukkala, E. "Risk of
esophageal, ovarian, testicular, kidney and bladder cancers and leukemia among Finnish work-
ers exposed to diesel or gasoline engine exhaust." Int J Cancer. 2004 Aug 20;111(2):28692.
Abstract: Occupational exposure to diesel exhaust has been classified as probably carcinogenic and
occupational exposure to gasoline engine exhaust as possibly carcinogenic to humans. Ear-
lier results concerning cancers other than lung cancer are scarce and inconsistent, and
exposure-response relations have seldom been reported. We followed up a cohort of all eco-
nomically active Finns born between 1906 and 1945 for 30 million person-years during
19711995. Incident cases of esophageal cancer (n = 2,198), ovarian cancer (5,082), testicu-
lar cancer (387), kidney cancer (7,366), bladder cancer (8,110) and leukemia (4,562) were
identified through a record linkage with the Finnish Cancer Registry. Occupations from the
population census in 1970 were converted to exposures to diesel and gasoline engine exhausts
with a job-exposure matrix (FINJEM). Cumulative exposure (CE) was calculated as product
of prevalence, level and estimated duration of exposure. The relative risk of cancer for expo-
sure categories in relation to the unexposed group was calculated using the Poisson regres-
sion model and adjusted for confounders. An increasing relative risk for ovarian cancer was
observed with the increasing CE of diesel exhaust (p for trend = 0.006). The relative risk in
the highest CE category was 3.69 (95% CI = 1.389.86). For gasoline engine exhaust, the rel-
ative risk was significantly increased only in the middle CE category (1.70; 95% CI =
1.112.62). Slight elevations of relative risk for bladder and kidney cancers were found at the
lowest exposure level of engine exhausts, largely attributable to drivers. No effect of the expo-
sures was observed for the other cancers. This study suggests an exposure-response relation
between diesel exhaust and ovarian cancer. Copyright 2004 Wiley-Liss, Inc.
Methodology: The study cohort comprised all economically active Finns born between 1906 and 1945.
The incident cases of esophageal cancer, ovarian cancer, testicular cancer, kidney cancer,
bladder cancer, and leukemia, diagnosed between 1971 and 1995 among persons born
between 1906 and 1945 were extracted from the Finnish Cancer Registry. A job-exposure
matrix was created on the basis of the census occupation and a national job-exposure matrix
(FINJEM). The exposure estimates were based on exposure measurements, hazard surveys,
and the judgments of 20 Finnish occupational hygienists. Since the exposure to diesel
exhaust decreased in most occupations between 1945 and 1984, cumulative exposure was
estimated for 5-year birth cohorts. Cumulative exposure to diesel exhaust was categorized
into three categories: lowest, middle, and highest, in mg/m3-years. Risk ratios were con-
trolled for cancer-specific confounding factors: socioeconomic status, cigarette smoking,
alcohol consumption, body mass index (BMI), number of children (for women), and occu-
pational exposure to ionizing radiation and aromatic hydrocarbon solvents.
Scope of Work: To assess the risk of leukemia and cancers of the esophagus, ovary, testis, kidney and blad-
der suspected to be associated with engine exhausts.
Sample Size: 2,198 cases of esophageal cancer, 5,082 cases of ovarian cancer, 387 cases of testicular can-
cer, 7,366 cases of kidney cancer, 8,110 cases of bladder cancer, and 4,562 cases of leukemia
Industry Sector: Truck drivers; no further characterization
Major Limitations: Exposure data not specific to individual cases
Findings Directly Related Driver Health (General)
to HOS (include page
references): Standard incidence ratios of all six types of cancer in truck drivers were all greater than 1.0
and leukemia was statistically significant (Table II). Relative risks for cancers in occupations
OCR for page 17
18
exposed to high, middle, or low levels of engine exhaust were significant for high cumula-
tive exposure to diesel exhaust and ovarian cancer (Table III). Relative risks for high or mid-
dle cumulative exposures were all insignificant for esophageal cancer, testicular cancer and
leukemia. Kidney and bladder cancer were associated with low exposures. "Applying more
sophisticated analysis to the same data, the present study revealed a positive exposure-
response relation between ovarian cancer and diesel exhaust." (p. 290) "In the present study,
we did not observe any positive exposure-response relations between engine exhausts and
the other 5 cancers." (p. 290)
Reviewer's Notes: This study addresses general causality as well as dose-response. Relative risks for all six
types of cancer were greater than 1. Regarding dose-response, this was a negative study
except for the interesting association between ovarian cancer and high cumulative exposure
to diesel exhaust.
OCR for page 18
19
Reviewer: Susan Buchanan
CompleteTitle: Jansen, N., Kant, I., van Amelsvoort, L., Nijhuis, F., and van den Brandt, P. "Need for
recovery from work: evaluating short-term effects of working hours, patterns and sched-
ules." Ergonomics. 2003 Jun 10;46(7):66480.
Abstract: In this paper working hours, patterns, and work schedules of employees were evaluated in
terms of need for recovery from work. Self-administered questionnaire data from employ-
ees of the Maastricht Cohort Study on Fatigue at Work (n = 12,095) were used. Poisson
regression analyses and multivariate logistic regression analyses revealed that higher work-
ing hours a day and working hours a week generally went together with more need for
recovery from work. Overtime work was associated with higher need for recovery from
work in both genders. Both male and female three-shift or irregular shift workers had higher
odds of elevated need for recovery compared with day workers. When additionally control-
ling for work-related factors, need for recovery levels among shift workers substantially low-
ered. This study clearly showed that working hours and schedules are associated with need
for recovery from work, with different associations for men and women. The associations
between work schedules and need for recovery from work were very interrelated with other
work-related factors. Future studies could further investigate the possibility that (a) shift
work might function as a proxy of other work-related factors that explain the different lev-
els in need for recovery from work or (b) job demands are perceived higher among shift
workers and may therefore lead to more need for recovery from work.
Methodology: Data from a baseline questionnaire from a large study on fatigue at work was used. Partic-
ipants were employees of 45 different companies in The Netherlands. Three populations
were studied: A. day employees only, B. day workers with vocation-level education only,
and C. workers with 26 to 35 hr/wk of work, which would include those working on 5-shift
systems. The Need for Recovery scale used was derived from the Dutch Experience and
Assessment of Work questionnaire. The scale was derived using statements such as "I find
it hard to relax at the end of a working day" and "My job causes me to feel rather exhausted
at the end of a working day."
Scope of Work: The present study was designed to describe the magnitude of associations between work-
ing hours and need for recovery from work.
Sample Size: Population A: 5170, Population B: 2167, Population C: 815
Industry Sector: n/a
Major Limitations: No information on occupation. Healthy worker effect might be seen in workers who choose
to work shifts. This would underestimate the effect.
Findings Directly Related Recovery/Restart Periods
to HOS (include page
references): In men, continuous Need for Recovery scores were significantly associated with working
more than 40 hr per week compared with fewer hours per week, working 9 to 10 hr per day
compared with working fewer hours per day, and working overtime frequently. Working
25 hr per week was also significant. These results were controlled for age, disease, job
characteristics of physical, emotional, and psychological demands. Using dichotomous out-
come for Need for Recovery (highest quartile vs. lowest quartile), results in men showed
significant associations between high need for recovery and working 9 to 10 hr per day,
working more than 40 hr per week, and working frequent overtime. No dose-response
analyses were performed. Regarding shift work, three-shift workers were significantly more
likely to need recovery time from work than day workers.
OCR for page 19
20
Author's conclusion: "The study showed that high working hours a day and high working
hours a week generally went together with a higher need for recovery, confirming our
hypothesis that day workers with many working hours a week report more need for recov-
ery from work compared to employees working less hours a week. Extension of the work-
ing day, in terms of overtime work, was particularly associated with more need for recov-
ery in both men and women." (p. 674)
Reviewer's Notes: This study, with a large sample, showed significant need for recovery from work in those
working 9 to 10 hr a day, more than 40 hr per week, and overtime.
OCR for page 20
21
Reviewer: Susan Buchanan
Complete Title: Miyamoto, M., Shirai, Y., Nakayama, Y., Gembun, Y., and Kaneda, K. "An epidemio-
logic study of occupational low back pain in truck drivers." J Nippon Med Sch. 2000
Jun;67(3):18690.
Abstract: The factors involved in occupational LBP occurring in professional drivers were investi-
gated epidemiologically with questionnaires (92 items) including LBP symptoms, personal
factors and occupational factors. The responses of 153 of 181 truck drivers who work in a
large chemical industry corporation were analyzed after they had completely filled in ques-
tionnaires. As analysis of the results shows, the prevalence of LBP in 1 month of the sur-
vey was 50.3%. Correlating among data of personal factors and LBP, the prevalence of LBP
was significantly higher in the drivers (odds ratio of 2.7) who answered "yes" to the item
"shortage of spending time with family" than in the drivers who did not answer yes. The
occupational factors, working load and working environment showed no correlation with
the prevalence of LBP. In contrast, 3 items of the working format related significantly to
the prevalence of LBP: irregular duty time (odds ratio of 3.0), short resting time (2.4), and
long driving time in a day (2.0). Eighty-one of the 153 drivers (52.9%) pointed out the rela-
tionship between LBP and work, especially work which involves vibration or road shock.
Our results and the results from previously published studies suggested that vibration is an
obvious risk factor for LBP. From the viewpoint of prophylaxis, an improvement in work-
ing conditions reduces the incidence of drivers' LBP to some extent.
Methodology: Truck drivers who work for a large chemical industry corporation completed questionnaires.
The questionnaire had 92 items with sections on LBP symptoms, personal factors, and occu-
pational factors including working load, working environment, and working format.
Scope of Work: To investigate by use of questionnaires, the prevalence of LBP symptoms and its risk fac-
tors among truck drivers.
Sample Size: 153 completed questionnaires
Industry Sector: Truck drivers, no further characterization
Major Limitations: No information on participant recruitment. Were they volunteers who might be more likely
to have symptoms? No information was given on job types or exposures of participants.
They all worked for the same company so one might not be able to generalize these results.
Details on risk factors were lacking: what do irregular duty time and short resting time mean
exactly? Self-reported symptoms of back pain may not indicate medical condition.
Findings Directly Related Driver Health (General)
to HOS (include page
references): Lack of sleeping time was a risk factor for LBP but was not significant. Working load and
working environment factors were not significant, although some associations were posi-
tive. Two working format factors were significant: irregular duty time and short resting
time. Insignificant but positive working format factors were long driving time in a day, long
driving time in a week, long working time in a day, irregular meal time, and long working
time in a week. (See Table 4, p. 189.)
Reviewer's Notes: Despite the limitations noted above, this was a decent sized sample showing a significant
relationship between LBP and irregular duty time and short resting time. Several other
working format factors showed positive associations but were not significant. Overall this
study suggests a relationship between driving hours in a day and LBP.
OCR for page 21
22
Reviewer: Susan Buchanan
Complete Title: Magnusson, M.L., Pope, M.H., Wilder, D.G., and Areskoug, B. "Are occupational drivers at
an increased risk for developing musculoskeletal disorders?" Spine. 1996 Mar 15;21(6):7107.
Abstract: Study Design: This study analyzed the role of exposure to driving and other covariates in
reports of back, neck, and shoulder pain and resultant disability. Cohorts in Sweden and the
United States were compared. Objectives: To establish the effect of mechanical and psy-
chosocial factors in reporting back, neck, and shoulder pain and work loss. Summary of
Background Data: There are numerous reports of a positive relationship between back pain
and driving. However, exposure data are minimal. The influence of job satisfaction has not
been assessed. Methods: The physical factors affecting reports of back, neck, and shoulder
pain were investigated in a two-country cohort study of bus and truck drivers and sedentary
workers. Vibration exposure was obtained by directly measuring the vibration imposed on
the driver during a typical work day. Lifting exposure was attained by questionnaire. Cumu-
lative exposure was computed based on work history. Musculoskeletal health information
was based on a modified Nordic questionnaire, and other questionnaires recorded the phys-
ical and psychosocial aspects of the work environment. Results: Of the sample, 50%
reported LBP, with no difference between countries. The highest risk factors (odds ratios)
for back and neck pain were long-term vibration exposure, heavy lifting, and frequent lift-
ing. A combination of long-term vibration exposure and frequent lifting carried the highest
risk of LBP. Work loss from LBP was influenced by perceived job stress. Conclusions:
Vibration (resulting from driving) and lifting cause back, neck, and shoulder pain, whereas
inability to work seems affected by stress at work.
Methodology: Participants were recruited by personal contact with workers in several companies in Ver-
mont and in Gothenburg, Sweden, who were male truck drivers or bus drivers. Sedentary
workers served as the control group. Musculoskeletal health information was based on
modified Nordic questionnaires (a standardized questionnaire used to assess musculo-
skeletal symptoms.) Another questionnaire had detailed questions about the work environ-
ment and the amount of lifting, sitting, standing, and driving on the job. Vibration levels
during representative driving conditions were measured. The summed products of "aver-
age acceleration" × "exposure duration" represented the daily vibration dose for that
driver. Long-term vibration exposure was calculated as the product of daily exposure dose
and years on the job as drivers.
Scope of Work: To compare the effect of exposure to vibration on drivers' back, neck, and shoulder pain
with those of control subjects in cohorts in two countries.
Sample Size: U.S.: 124, Sweden: 241
Industry Sector: Bus drivers and truck drivers; no further detail given
Major Limitations: Did not explain recruitment nor any detail on the participants. Did not measure awkward
postures and seated exposure.
Findings Directly Related Working Conditions (Environmental except sleeper berth)
to HOS (include page
references): "American truck drivers had a significantly higher daily exposure (to vibration) than bus
drivers." (p. 9 of 16) "Those who reported LBP had a significantly higher total long-term
vibration exposure than those who did not report LBP in those aged 35 to 45 years. Long-
term exposure to vibration (equal to the vibration exposure over years in the profession)
OCR for page 22
23
was the strongest predictor of length of sick leave because of LBP." (p. 9-10 of 16) "Sig-
nificant single risk factors were . . . long-term vibration exposure." (p. 11 of 16)
Reviewer's Notes: Because this study did not elaborate on sampling and recruiting methods, it is difficult to
judge its validity; however, results show that long-term exposure to vibration was a signif-
icant risk factor for LBP.
OCR for page 37
38
Reviewer: Susan Buchanan
Complete Title: Boffetta, P. and Silverman, D.T. "A meta-analysis of bladder cancer and diesel exhaust
exposure." Epidemiology. 2001 Jan;12(1):12530.
Abstract: The aim of this study is to review and summarize the available epidemiologic studies of
bladder cancer and occupational exposure to diesel exhaust. We retrieved relevant studies
and abstracted their characteristics and results. We assessed the heterogeneity of the results
to decide whether to perform a fixed-effects model meta-analysis. We identified 35 relevant
studies. No overall meta-analysis was performed because of heterogeneity in results.
Results of railroad workers (N = 14) suggested an increased occurrence of bladder cancer,
but we did not conduct a meta-analysis. The summary relative risk (RR) among truck driv-
ers was 1.17 (95% CI = 1.061.29, 15 studies) and that among bus drivers was 1.33 (95%
CI = 1.221.45, 10 studies). Ten studies considered diesel exhaust exposure based on a job
exposure matrix or a similar approach; the summary relative risk for these studies was 1.13
(95% CI = 1.001.27). A positive dose-response relationship was suggested by 10 of the
12 studies that provided relevant information. The summary relative risk for high diesel
exposure was 1.44 (95% CI = 1.181.76). There was some evidence of publication bias,
however, with a lack of small studies with null or negative results. Our review suggests that
exposure to diesel exhaust may increase the occurrence of bladder cancer, but the effects
of misclassification, publication bias, and confounding cannot be fully taken into account.
Methodology: Searched epidemiologic literature for studies on cancer after exposure to diesel exhaust and
for studies on occupational risk factors for bladder cancer. Concentrated on 5 occupational
groups including truck drivers.
Scope of Work: To summarize available results of epidemiologic studies of the association between occu-
pational exposure to diesel exhaust and occurrence of urinary bladder cancer.
Sample Size: 29 studies on bladder cancer and exposure to diesel exhaust
Industry Sector: Truck drivers, no further characterization
Major Limitations:
Findings Directly Related Working Conditions (Environmental except sleeper berth)
to HOS (include page
references): Fifteen results were available for truck drivers. Exposure was characterized by either years
of employment or job exposure matrix. For exposure to diesel exhaust characterized as
"high," relative risk was 1.44 and significant. For "any exposure," relative risk was 1.23 and
significant. See Table 5. "Out of 12 results for `heavy exposure,' 10 were higher than their
corresponding results for `any exposure,' and only one of the remaining was lower." (p. 129)
Reviewer's Notes: Meta-analysis showing positive evidence for increased risk of bladder cancer among truck
drivers with "any exposure" to diesel exhaust. Truck drivers with "high" exposure were sig-
nificantly more likely to have bladder cancer than those with lower levels of exposure.
OCR for page 38
39
Reviewer: Susan Buchanan
Complete Title: Lings, S. and Leboeuf-Yde, C. "Whole-body vibration and low back pain: a systematic, crit-
ical review of the epidemiological literature 19921999." Int Arch Occup Environ Health
(2000);73: 290297.
Abstract: Objectives: A previous extensive review of the literature including that from the middle of
1992 concluded that WBVs may contribute to low back pain, but that the exposure-response
relationship had not been clarified. We reviewed the literature of the past 7 years to find out:
(i) whether there is evidence in the recent epidemiological literature for a causal associa-
tion between WBV and LBP, and (ii) if there is evidence in the recent literature for a dose-
response relationship between WBV and LBP. Methods: All relevant epidemiological arti-
cles, which were obtained through a search in the databases MEDLINE, OSH-ROM, and
TOXLINE, and through personal communication, were reviewed independently by the two
authors, using a checklist. Results: Twenty-four original articles concerning the association
between WBV and the lower back were retained for use. Only seven articles passed our pre-
determined quality criteria. Of the seven reports, one showed increased frequency of lum-
bar prolapse in occupational drivers, and six showed LBP to be more frequent in WBV-
exposed groups. Only two of the four articles reporting on dose showed a dose-response
association. Conclusions: Despite the lack of definite evidence, we found sufficient reasons
for the reduction of WBV-exposure to the lowest possible level. If new knowledge is to be
produced, good prospective studies with repeated measurements of exposure, analyses of
work postures, and clear definitions and subgroupings of LBP are needed. Other research
in this field should be given up, and the resources used for more important issues, as the
size of the problem of WBV is probably on the decrease because of the technical prophy-
lactic developments that are already in progress.
Methodology: Literature review of MEDLINE, OSH-ROM, and TOXLINE of all original epidemiologi-
cal articles published from 1992-1999. They were reviewed by the two authors, indepen-
dently using predetermined quality criteria.
Scope of Work: To conduct a review of the literature on WBV and LBP since the issue was last reviewed
in 1992. Questions addressed were: Is there evidence for a definite association between
WBV and LBP? Is there evidence for a dose-response relationship between WBV and LBP?
Sample Size: 24 original reports were identified: 21 passed initial screening, 7 studies fulfilled at least
5 of the 6 quality criteria.
Industry Sector: Various
Major Limitations: Authors seemed a little opinionated, may have had an agenda
Findings Directly Related Working Conditions (Environmental except sleeper berth)
to HOS (include page
references): Six reports showed LBP to be more frequent in study groups and one showed increased fre-
quency of hospitalization for disc herniation in drivers. Of the four studies on dose-response,
two showed an association. ". . . despite at least 24 epidemiological publications address-
ing the question, the evidence still remains weak." (p. 291)
Authors' conclusion: "The six reports that best fulfilled our quality criteria were predomi-
nantly in favour of a positive association between WBA and LBP . . . Hence it can still be
concluded that here is probably an association between WBV and LBP," ( but not causal-
OCR for page 39
40
ity) "Existing knowledge yields sufficient reasons for reducing exposure to the lowest pos-
sible level." (p. 296)
Reviewer's Notes: Although the authors give mixed conclusions about the effect of WBV on LBP, most of the
studies included in the literature review found positive associations. However, evidence for
dose-response was weak.
OCR for page 40
41
Reviewer: Peter Orris
Complete Title: Jensen, Marianne V. Tuchsen, F., and Orhede, E. "Prolapsed Cervical Intervertebral Disc
in Male Professional Drivers in Denmark, 19811990: A Longitudinal Study of Hospital-
izations." Spine 1996, October 21(20): 23522355.
Abstract: Study Design: This study of professional drivers is a part of a longitudinal record linkage
study of all economically active men in Denmark, identified on January 1, 1981. Informa-
tion about the main occupation was identified in 1980. The cohort was followed for first
hospitalization with prolapsed cervical intervertebral disc until December 31, 1990. Objec-
tives: To examine the risk of prolapsed cervical intervertebral disc in all Danish professional
drivers, and to analyze exposures of the male drivers in a sample of all Danish male drivers.
Methods: A standardized hospitalization ratio was calculated for each subgroup of drivers
using all economically active people as the standard. Additional exposure information was
extracted from a national survey on work environment. Almost all men in occupations
involving professional driving had a statistically significant elevated risk of being hospi-
talized with prolapsed cervical intervertebral disc. Conclusions: Professional driving is a
risk factor for prolapsed cervical intervertebral disc.
Methodology: Methods: This study of professional drivers is a part of a longitudinal record linkage study
of all economically active men in Denmark, identified on January 1, 1981. Information
about the main occupation was identified in 1980. The cohort was followed for first hospi-
talization with prolapsed cervical intervertebral disc until December 31, 1990. A standard-
ized hospitalization ratio was calculated for each subgroup of drivers using all economi-
cally active people as the standard. Additional exposure information was extracted from a
national survey on work environment.
Scope of Work: Only a few studies on occupation and prolapsed cervical intervertebral disc have been pub-
lished. These studies suggest that professional driving may be a risk factor for development
of prolapsed cervical intervertebral disc. Drivers are exposed to WBVs, heavy lifting, and
a sedentary position. Other potential exposures are accelerations and decelerations and
whiplash accidents. Such exposures may be involved in the causation of prolapsed cervical
intervertebral disc.
Sample Size: 1.3 million economically active men in Denmark
Industry Sector: Various
Major Limitations: Unable to separate WBV from other musculoskeletal stressors on drivers
Findings Directly Related Driver Health (General)
to HOS (include page
references): Almost all men in occupations involving professional driving had a statistically significant
elevated risk of being hospitalized with prolapsed cervical intervertebral disc.
Reviewer's Notes: An objective prospective study identifying professional driving as a risk factor for the
development of prolapse of a cervical intervertebral disc.
OCR for page 41
42
Reviewer: Susan Buchanan
Complete Title: Gustavsson, P., Plato, N., Hallqvist, J., Hogstedt, C., Lewne, M., Reuterwall, C., and
Scheele, P. "A population-based case-referent study of myocardial infarction and occupa-
tional exposure to motor exhaust, other combustion products, organic solvents, lead, and
dynamite. Stockholm Heart Epidemiology Program (SHEEP) Study Group." Epidemiol-
ogy. 2001 Mar;12(2):2228.
Abstract: This case-control study investigated the risk of MI from occupational exposure to motor
exhaust and other combustion products. We identified first-time, nonfatal MIs among men
and women 45 to 70 years of age in Stockholm County from 1992 through 1994. We
selected referent subjects from the population to match the demographic characteristics of
the cases. A lifetime history of occupations was obtained by questionnaire. The response
rate was 81% for the cases and 74% for the referents, with 1,335 cases and 1,658 referents
included in the study. An occupational hygienist assessed occupational exposures, coding
the intensity and probability of exposure for each subject. We adjusted relative risk esti-
mates for tobacco smoking, alcohol drinking, hypertension, diabetes mellitus (DM), being
overweight, and physical inactivity at leisure time. The relative risk of MI was 2.11 (95%
CI = 1.233.60) among those who were highly exposed and 1.42 (95% CI = 1.051.92)
among those who were intermediately exposed to combustion products from organic mate-
rial. We observed an exposure-response pattern, in terms of both maximum exposure inten-
sity and cumulative dose. Exposure to dynamite and organic solvents was possibly associ-
ated with an increased risk. The other exposures were not consistently associated with MI.
Methodology: Case-control study of first-time MI. Cases were identified from intensive care units in
Stockholm County. Controls were selected from a computerized population register and
were matched according to sex, age, and hospital catchment area. Subjects completed ques-
tionnaires on occupational history. A job exposure matrix was created by industrial hygien-
ists using unpublished and published occupational hygiene reports, personal contacts and
professional experience to quantify intensity of exposure using estimated exposure preva-
lence within each occupation (in terms of annual average of 8-hr work day exposures to
motor exhaust.) Relative risks were adjusted for smoking, alcohol intake, hypertension,
weight, DM, and physical inactivity.
Scope of Work: To investigate the risk of MI from occupational exposure to motor exhaust and other com-
bustion products.
Sample Size: 1,335 case and 1,658 controls
Industry Sector: Did not specify
Major Limitations: Those who survived MI were interviewed. Those not surviving were excluded (history of
exposure not taken from surviving family members). Exposures to exhaust were estimated,
not measured. Did not control for cholesterol results. Did not specify type of exhaust.
Findings Directly Related Working Conditions (Environmental except sleeper berth)
to HOS (include page
references): (Actual journal page numbers are not given in this on-line document.) Working conditions:
There was a non-significant elevation of relative risk of MI with moderate exposure to
motor exhaust. No dose response trend was seen. There was a significantly increased rela-
tive risk of MI with high or intermediate exposure to combustion products, (besides motor
OCR for page 42
43
exhaust). The same results were found when cumulative exposure was estimated. (See
Tables 2 and 4.)
"We found some indications of an increased risk of MI in association with exposure to
motor exhaust, but no firm evidence of an exposure-response relation."
Reviewer's Notes: The results are suggestive of increasing MI risk with cumulative exposure to motor exhaust.
OCR for page 43
44
Reviewer: Susan Buchanan
Complete Title: Chen, J.C., Dennerlein, J.T., Shih, T.S., Chen, C.J., Cheng, Y., Chang, W.P., Ryan, L.M.,
and Christiani, D.C. "Knee pain and driving duration: a secondary analysis of the Taxi Driv-
ers' Health Study." Am J Public Health. 2004 Apr;94(4):57581.
Abstract: Objectives: We explored a postulated association between daily driving time and knee pain.
Methods: We used data from the Taxi Drivers' Health Study to estimate 1-year prevalence
of knee pain as assessed by the Nordic musculoskeletal questionnaire. Results: Among
1,242 drivers, the prevalence of knee pain, stratified by duration of daily driving (6,
>6 through 8, >8 through 10, and >10 hr), was 11%, 17%, 19%, and 22%, respectively.
Compared with driving 6 or fewer hr per day, the odds ratio of knee pain prevalence for driv-
ing more than 6 hr per day was 2.52 (95% CI = 1.364.65) after adjustment for socioeco-
nomic, work-related, and personal factors in the multiple logistic regression. Conclusions:
The dose-related association between driving duration and knee pain raises concerns about
work-related knee joint disorders among professional drivers.
Methodology: Taxi drivers in Taipei city were recruited during free government physical exams. Ques-
tionnaires were completed which included information on daily driving hours, among other
work factors, and presence of knee pain in the previous 12 months.
Scope of Work: To test the hypothesis that prolonged driving is associated with increased knee pain among
taxi drivers.
Sample Size: 1,242 taxi drivers (of at least 1 years' duration)
Industry Sector: Taxi drivers
Major Limitations: Used self-reports of knee pain. Presence of pain does not necessarily indicate a medical
condition.
Findings Directly Related Shifts/Time of Day/Circadian
to HOS (include page
references): Workers with >10 hr of daily driving had significantly increased risk of knee pain. There
was a dose response in history of knee pain and daily driving times of 6 hr, 6 to 8 hr, 8 to
10 hr, and >10 hr (all significant) when controlled for age, gender, BMI, income, other
demographics, and physical exertion during work and leisure time, and professional senior-
ity. No associations were found between knee pain and vehicle manufacturers or engine
sizes. Authors' conclusion: "Our exploratory analyses of the TDHS (Taxi Drivers' Health
Study) baseline data revealed a strong and robust association between long driving times
and knee pain. The public health impact of work-related knee pain among professional driv-
ers could be substantial."
Reviewer's Notes: Agree with previous quote.
OCR for page 44
45
Reviewer: Susan Buchanan
Complete Title: Barton, J. and Folkard, S. "Advancing Versus Delaying Shift Systems." Ergonomics
1993;36(1-3):5964.
Abstract: Two-hundred sixty-one shift workers from a range of UK industrial and service organiza-
tions took part in a study to determine the impact of the direction of shift rotation on the
health and well-being of the individuals concerned. All the systems were continuous, rotat-
ing over three shifts. Systems were classified according to whether they delayed (i.e.,
rotated in a forward direction) or advanced (i.e., rotated in a backward direction). In addi-
tion, advancing systems were divided into those which incorporated a quick return (i.e., a
break of only 8 hr when changing from one shift to another) and those which did not. The
results add some support for the use of delaying as opposed to advancing systems, and high-
light the detrimental affects of incorporating a quick return into an advancing system.
Methodology: All subjects completed the Standard Shift Work Index. ANCOVA was performed to deter-
mine the effect of the direction of shift rotation on each outcome measure.
Scope of Work: To examine the relative effect of advancing or delaying systems on shift workers.
Sample Size: A total of 261 industrial and service shift workers from a range of occupations took part in
the study
Industry Sector: Shift workers from steel industry, power industry, post office, police force, and air traffic
control officers
Major Limitations: There was no information given on the sampling method, whether the participants were vol-
untary or randomly selected.
Findings Directly Related Shifts/Time of Day/Circadian
to HOS (include page
references): Compared with the delayed rotating shift system, workers on the advancing system were
significantly more likely to complain of digestive and cardiovascular disorders, chronic
fatigue, and cognitive anxiety. (See Table 1, p. 61.)
"Comparing advancing systems with and without a quick return produced few significant
differences, yet overall, it was the former who reported poorer physical health." (p. 63)
"In conclusion it would appear that the critical feature may not be related entirely to the
direction of rotation but to a combination of direction and the length of break when chang-
ing from one shift to another." (p. 64)
Reviewer's Notes: This article adds to the body of literature associating a change in sleep schedule (a.k.a. cir-
cadian rhythm) with GI and cardiovascular effects.
OCR for page 45
46
Reviewer: Susan Buchanan
Complete Title: Morgan, L., Arendt, J., Owens, D., et al. "Effects of the endogenous clock and sleep time
on melatonin, insulin, glucose and lipid metabolism." J Endocrin 1998;157:443451.
Abstract: This study was undertaken to determine whether the internal clock contributes to the hor-
mone and metabolic responses following food, in an experiment designed to dissociate
internal clock effects from other factors. Nine female subjects participated. They lived
indoors for 31 days with normal time cues, including the natural light and darkness cycles.
For 7 days they retired to bed from 0000 to 0800. They then underwent a 26-hr `constant
routine' (CR) starting at 0800 h, being seated awake in dim light with hourly 88 Kcal drinks.
They then lived on an imposed 27-hr day for a total of 27 days. A second 26-hr CR, start-
ing at 22 hr was completed. During each CR salivary melatonin and plasma glucose, triglyc-
eride (TAG), non-essential fatty acids (NEFA), insulin, gastric inhibitory peptide (GIP) and
glucagons-like peptide-1 (GLP-1) were measured hourly. Melatonin and body temperature
data indicated no shift in the endogenous clock during the 27-hr imposed schedule. Post-
prandial NEFA, GIP and GLP-1 showed no consistent effects. Glucose, TAG, and insulin
increased during the night in the first CR. There was a significant effect of both the endoge-
nous clock and sleep for glucose and TAG, but not for insulin. These findings may be rel-
evant to the known increased risk of cardiovascular disease amongst shift workers.
Methodology: Subjects were observed for 31 days and were required to live on an imposed 27-hr day cycle.
Activity was monitored with wrist monitors and rectal temps were recorded. Blood levels
for triacylglycerol, insulin, and glucagon-like peptide. Salivary melatonin was measured.
Scope of Work: To determine to what extent the internal clock contributes to the hormonal and metabolic
responses following a meal.
Sample Size: 9 female undergraduates
Industry Sector: n/a
Major Limitations: Testing was performed in experimental conditions which might not reflect real life scenarios.
Findings Directly Related Shifts/Time of Day/Circadian
to HOS (include page
references): "Dissociation of the internal clock and sleep in the second constant routine leads to a
dampening of the peak response to glucose and the appearance of two comparable peaks,
suggesting a `spreading' of glucose intolerance such that it occurs at two periods of the
day." (p. 448449) "The present study has shown for the first time that the length of wake-
fulness also has an effect on glucose tolerance, independent of any circadian rhythm or
sleep itself." (p. 449)
Reviewer's Notes: This group previously reported that immediately after a simulated 9-hr advance, such as
might be found in rotating shift work, postprandial insulin and glucose responses to a stan-
dard mixed meal were significantly greater than to the same meal at the same external clock
time before the phase shift. The changes were suggestive of insulin resistance, a risk factor
for cardiovascular disease.
This study takes this issue a step further and tries to separate out the possible effect of a cir-
cadian rhythm change. Results showed that insulin resistance indeed worsened with a
longer sleep-wake cycle but was independent of changes in the internal clock or circadian
rhythm.
OCR for page 46
47
Reviewer: Susan Buchanan
Complete Title: Scott, A. "Shift Work and Health." Primary Care Dec 2000;27(4):10571078.
Abstract: Night work and rotating shift work disrupt the circadian timing system. This disruption may
produce significant deleterious symptoms in some workers. Certain medical conditions may
be aggravated by shift-work scheduling, and shift workers are at increased risk of experi-
encing cardiovascular, GI, and reproductive dysfunction. Vulnerable individuals may
develop clinical depression when working shifts. Primary care practitioners may intervene
by providing medical surveillance and education programs for shift-working patients and
their families.
Methodology: Written as a chapter with 166 references. It is not original research but is an excellent review
of the current literature up to 2000.
Scope of Work: This is a chapter on Occupational and Environmental Medicine in a hard bound journal. It
offers an overview of circadian rhythms and the health effects of night work and sleep depri-
vation, and offers a review of specific medical disorders associated with shift work.
Sample Size: n/a
Industry Sector: n/a
Major Limitations: This is not original research. It assumes validity of its references.
Findings Directly Related Shifts/Time of Day/Circadian:
to HOS (include page
references): Circadian rhythm: ". . . each time the work schedule rotates, for a period of time after the
time shift, the circadian system will be in a desynchronized state." (p. 1059)
Shift-work intolerance: "Up to 20% of shift workers may have a disproportionate number
of symptoms of illness when assigned to chronobiologically poorly designed shift-work
schedules involving night work." (p. 1061) "Specific factors that affect shift work tolerance
include: . . . rotating or fixed, number of nights worked consecutively, frequency of week-
ends off, length of shift and starting time, overtime requirements, predictability of sched-
ule." (p. 1061)
GI Disorders: "Gastrointestinal dysfunction is common in shift workers. . . . Some studies
have not found an increased incidence of peptic ulcer disease in shift workers, but the
majority of studies addressing this outcome have. Including non-English reports, 16 of
24 studies evaluating PUD and shift work found shift workers to be at greater risk of devel-
oping PUD than day workers. . . . Circadian rhythm disruption also contributes to shift-
work related GI dysfunction." (p. 1062)
Cardiovascular morbidity: "Although there are studies that have not found changes in lipid
profiles related to shift work, a recent thorough review of this research concluded that the
better studies do indicate that shift workers have somewhat higher levels of cholesterol as
well as triglycerides." "Although early studies concluded shift work was not associated with
an increase in CVD, most of the more recent, better epidemiologically designed studies
have found an increased risk of CVD." (p. 1063)
Reproductive Health: Studies quoted showed shift work and rotating shift work to be asso-
ciated with higher prematurity rate, low birth weight, spontaneous abortion, and decreased
fertility rate." (p. 1064-65)
OCR for page 47
48
Exacerbation of Medical Disorders: "Shift work also may aggravate certain medical disorders
related to circadian rhythm disruption, psychosocial stress, or sleep deprivation. Conditions
that may be exacerbated or aggravated by irregular schedules or night work and are therefore
potential contraindications for shift work include: GI disorders, DM, epilepsy, cardiovascu-
lar disease, psychiatric disorders, sleep disorders, reproductive dysfunction." (p. 1066)
Reviewer's Notes: This chapter, with 166 references, confirms the multiple health issues related to shift work
and rotating shift work including GI, cardiovascular, and reproductive health.
