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 120
123
HEALTH EFFECTS REFERENCES REVIEW
EXECUTIVE SUMMARY ficient reason to be concerned about a possible link between
long hours and physical health outcomes such as cardiovas-
The purpose of Part I of this synthesis was to provide infor- cular disease and diabetes. Several investigations of the acute
mation that clearly discussed in a scientific, experimental, biochemical effects of acute sleep restriction supported this
qualitative, and quantitative way the relationship between the concern due to the increase in risk factors for diabetes and
hours a person works, drives, and the structure of the work obesity and an additional study noted that self-reported daily
schedule (on-duty/off-duty cycles, time on task, especially short sleep duration was associated with an increase in the
time in continuous driving, sleep time, etc.) and the impact rate of diabetes.
on the health of truck drivers. The issues of cardiovascular
disease, cancer, musculoskeletal disorders, gastrointestinal
disorders, reproductive health effects, and the effects of PROCESS AND METHODOLOGY
vibration and noise were reviewed in this part. Part II covers
additional articles on lung cancer and the health effects of Literature Search Source and Terms
short sleep duration.
In Part II, the research team reviewed additional available FMCSA provided a list of 266 references cited in public
information provided with respect to data relevant to driver comments on the advanced NPRM.
health potentially associated with the 2003 HOS Regulations.
FMCSA provided a list of 266 references included in com-
ments on the proposed rules. After review of the titles or Selection Criteria
abstracts, 256 were judged to cover matters that were either
The original list provided by the FMCSA contained 266
previously reviewed in Part I or were outside the scope of
articles. Those not deemed appropriate by title (not relating
Part II, which focused solely on health effects, and not on the
to health effects) were eliminated, although the fatigue sec-
fatigue effects discussed in a later section of this review. The tion of Part II includes those references relating to fatigue
research team focused on references which utilized a scien- effects. The preliminary draft list then included 73 articles.
tific approach in analyzing new data. Ten references were Those not pertaining to health effects of truck driving or a
chosen and summarized based on the relevance of the article related exposure, duration of work shift or duration of sleep
to the health effects of the changes in HOS for truck drivers. were then removed from the list. Several citations taken
This review excluded articles that evaluated the health impact from lay press websites and those already reviewed in Part I
of shift work. were also eliminated. Articles on shift work were likewise
As stated in Part I, the literature indicates that lung cancer not included unless they specifically addressed short sleep
is likely caused by exposures to diesel exhaust and the longer duration.
that exposure lasts the more likely it is that a cancer will The remaining ten references were summarized by a pri-
develop. Additional evidence for this association was found mary reviewer based on the validity of the methodology, the
in the additional material reviewed yet tempered with respect relevance of the studied population to truck driving, and the
to truck drivers with the understanding that substantial expo- quality of the statistical analysis of health outcomes. These
sure misclassification may have occurred in job-derived were abstracted and summarized in the format prescribed by
exposure estimates. FMCSA. The three end points covered by these new refer-
An additional article (not included in Part I) on the rela- ences were (1) lung cancer, (2) WBV, and (3) the health effects
tionship of whole body vibration (WBV) and self-reported of short sleep duration.
low back pain again identified an association, although the
association was weak.
Finally, an additional study (not included in Part I) sug- REVIEW OF REFERENCES
gested that, in contrast to prior results, short sleep duration,
as low as 4.5 hours, may not affect mortality. Yet, the litera- The summaries are divided into the following subsections:
ture on sleep duration and health concludes that there is suf- lung cancer, WBV, and health effects of short sleep duration.
OCR for page 121
124
Lung Cancer tion compared with previously reviewed studies of exposed
workers.
Three articles addressed the association of lung cancer
and exposure to diesel exhaust. A case-control study using
a survey of the general population in Sweden (Gustavsson
et al. 2000) found a positive association as well as a dose- Health Effects of Short Sleep Duration
response relationship.
A large study using data from 1.1 million questionnaires
Two additional reports were reviewed that evaluated the
(Kripke et al.) investigated the mortality associated with short
strength of the methodologies of existing studies on the rela-
sleep duration and found that the best survival was experi-
tionship of truck driving to lung cancer. An extensive feasi-
enced by those reporting a usual sleep duration of 7 hours.
bility study conducted by the Health Effects Institute Diesel
When controlled for co-variants, the mortality risk associated
Epidemiology Working Group (Garshick et al. 2002) demon-
with short sleep all but disappeared, suggesting in contrast to
strates with its pilot data that long-haul drivers have a low
prior studies that short sleep duration, as low as 4.5 hours,
exposure to diesel exhaust compared with dock workers and
may not affect mortality.
suggests that new diesel technology may be an explanation.
A review of the literature on sleep duration and health
They also note that estimating exposure based on job alone, as
(Alvarez 2004) concludes that the metabolic changes asso-
is done in many studies, may give highly misclassified expo-
ciated with short-term sleep deprivation may provide a
sure assignments. Similarly, in an analysis of the risk assess-
potential mechanism for the effects of long-term sleep depri-
ment data by the same panel (HEI 1999), recommendations
vation on health. An extensive review of the literature on
were made regarding Quantitative Risk Assessment (QRA)
long working hours by the United Kingdom Safety Labora-
based on the current studies available. The research team con-
tory (White 2003) only briefly includes the health effects of
cluded that the railroad worker cohort study (Garshick 1988,
long hours. It concludes that there is sufficient reason to be
a secondary reference in Part I) has limited utility for quali-
concerned about a possible link between long hours and
tative risk assessment, but that the Steenland article (1998)
physical health outcomes such as cardiovascular disease and
also reviewed for Part I is potentially useful based on a QRA
diabetes.
approach.
Three studies addressed the metabolic changes which may
The report, Diesel and Health in America: the Lingering
result from acute sleep restriction. A controlled study of sleep
Threat, from the Clean Air Task Force in February 2005 mod-
restriction in healthy volunteers (Spiegel 1999) showed car-
eled the health effects of the current diesel fleet on the U.S.
bohydrate intolerance, and cortisol and thyrotropin abnor-
population as a whole (Schneider and Hill 2005). Despite the
malities similar to those seen in patients with type 2 diabetes
necessary assumptions inherent in this type of report, this
and aging. On the other hand, a survey study of sleep dura-
study concludes that increasing the weekly working hours of
tion with a sleep-lab component (Taheri 2004) did not find an
drivers is likely to increase their risk of cancer with the under-
association between sleep duration and insulin or glucose.
standing that new trucks, through changes in engine and cab
However, two hormones which control appetite were both
design, will mitigate this affect due to reduction in exposure.
found to be abnormal in sleep-deprived participants.
Finally, large survey study of self-reported sleep duration
WBV Effects and incidence of diabetes (Ayas et al. 2003), found a signifi-
cantly elevated risk of diabetes in those sleeping 5 hours per
In addition to the articles reviewed for Part I on the effects night which disappeared when elevated Body Mass Index
of WBV, one article reviewed for Part II (Palmer et al. 2003) (BMI) (a known risk factor for diabetes) was not controlled
showed a weak association between estimated vibration dose for. As BMI or obesity may itself be associated with short
and low back pain. However, this was a survey of the general sleep duration based on the studies of acute sleep deprivation,
population and vibration dose was estimated from self report this may not be an appropriate control as the effect may be
of vehicle use; both factors may explain the weaker associa- mediating rather than confounding.
