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3BACKGROUND Commercial truck, bus, and motorcoach drivers are expected to continually maintain full cognitive alertness while driving, and to sustain safe operating practices on our roadways, even during long highway trips. For decades there has been a common belief that many drivers in search of countermeasures to drowsy driving have taken to ingesting various chemical substances that might assist them in combating driver fatigue. Drivers occasionally may take a variety of psychoactive drugs, medications, sleep-inducing hypnotics, wakefulness-promoting stimulants, and a proliferation of other chemicals casually labeled as dietary and nutritional or health food supplements. Drivers do this to obtain adequate sleep during their off-duty hours or to boost their energy and prompt alertness while driving. The concern has been whether or not the individual or interactive and synergistic effects of such chemicals adversely affect their driving alertness, fatigue, performance, or health (Krueger CMV driver fatigue and wellness train-the-trainer experiences, 1996â2006; Krueger 2003, 2010). Additionally, physicians and other health care providers legitimately prescribe various medications to drivers for treat- ment of diseases, illnesses, and a myriad of medical problems, including insomnia or sleep disorders. Commercial motor vehicle (CMV) drivers also may take a wide variety of over- the-counter (OTC) medications to self-treat their ailments, whether medically diagnosed or not. Drivers are known to consume medications to alleviate or ameliorate such physio- logical conditions as allergies, rhinitis, being overweight or obese, musculoskeletal discomfort, or for a variety of other medical conditions, including attempts at cessation of tobacco use and smoking. Of particular concern is the belief that even while taking medications to treat ailments some commercial drivers may also ingest various chemicals as contained in nutritional supplements (beverages, food bars, etc.) in an effort to boost energy levels, enhance alertness, or combat driver fatigue. Two recent TRB publications identifying data gaps in truck and bus safety research determined that science-based information is needed to judge how drivers consuming such chemical substances affect their own driving alertness and performance, their sleep hygiene, fatigue management, and several basic health practices. A TRB Research Circular (Knipling 2007) presents a chapter on commercial driver health, wellness, and fitness (Krueger et al. 2007), and TRB CTBSSP Synthesis 15: Health and Wellness Programs for Commercial Drivers (Krueger et al. 2007b) identified the need for increased research on these topics. While developing the nationâs second ten-year plan for a National Occupational Research Agenda, the National Institute for Occupational Safety and Health also identified the need for research to determine the relationship between the use of chemical sub- stances by commercial drivers and any resultant short- and long-term health consequences or safety implications of such practices (National Institute for Occupational Safety and Health 2010). As a result of this heightened attention to commercial drivers partaking of chemical substances, this synthesis project was initiated to provide information on the relationship between the use of psychoactive chemicals and driver performance, safety, and health. OBJECTIVES AND SCOPE There were four principal objectives for this synthesis: 1. To present a synopsis of a sizeable portion of the scientific literature on a wide variety of psychoactive chemical substances that sometimes are consumed by commercial drivers, particularly insofar as the sub- stances may affect driver performance. 2. To provide an extensive bibliographic reference listing of published literature on these topics. 3. To administer a survey questionnaire to a small con- venience sample of medical examiners inquiring about their anticipated actions with respect to their assessment of chemical substances pertinent to conduct Commercial Driver Medical Examinations (CDMEs). 4. To survey a sampling of motor carrier officials regard- ing their company policies about drivers using chemi- cal substances. This synthesis study identified available information and research needs relating to the use of chemical substances by commercial drivers and is intended to provide up-to-date information to inform decision making for near-, mid-, and long-range planning of research and educational outreach programs. CHAPTER ONE INTRODUCTION
METHODOLOGY AND APPROACH Literature Review This synthesis provides a narrative review and description of much of what is known from the scientific literature about psychoactive chemicals that some commercial drivers at times ingest, and reports on the known and probable effects of such chemicals on operator performance, safety, and health. These substances include many prescription and self-administered medications, sleep-inducing hypnotics, wakefulness-promoting stimulants, and a large number of products best labeled as dietary and nutritional supple- ments, many of which contain psychoactive agents and are readily available over the counter in grocery and drug stores and at convenience stores located at fueling rest stops along the U.S. highways. Reports identified and reviewed included: â¢ Scientific journal articles presenting results of experi- ments involving psychoactive substances and equipment operator performance, as well as laboratory studies of generic performance and skill tests having a direct relationship to driving behavior (i.e., studies of drug effects on reaction time, psychomotor tracking, vigilance, judgment, decision making, and so on); â¢ Occupational health and safety reports pertaining directly to chemical substance use by transportation operators (commercial drivers, aviators, and others) and their performance; â¢ Rules and advisory guidelines from FMCSA published and available for use by the public and by CDMEs; â¢ Documents in the widely dispersed government- sponsored technical report literature, especially those of federal research organizations such as the U.S. military medical research and civil aeromedical research labora- tories, the National Institutes of Health research institutes, and public health centers (e.g., National Institute of Drug Abuse); and â¢ A variety of professional scientific publications, text- book chapters, committee reports, symposia proceedings, position papers, and others that are largely produced outside the refereed journal literature. Also provided as Appendix B is a brief analytical review of the medical and performance research that supports the current operational policy statements of the several U.S. military services, each of which permits selective, limited- time, operational use of psychoactive chemical substances to be taken by military personnel under highly controlled military circumstances. Such state-of-the-art/practice research portends the potential, but with significant accompanying cautions, for employing psychoactive chemicals for operational fatigue countermeasures in other work settings. It also anticipates discussion of whether such chemical substances would ever 4 be usable in practice in select commercial transportation applications. The literature review presented here is of the narrative type. It describes and appraises previous work, but does not specify methods by which any particular studies cited were identified, selected, and/or evaluated. Many of the citations are from scientific peer-reviewed journals. Many textbook chapters cited were written by leading scientists in their fields, whose knowledge of decades of their own and their peersâ published works lends credibility to their synopsis on select topics. The choice of which articles to cite in this narrative review was largely determined by the synthesis teamâs judg- ment that a particular reference explicated the points being made or provided an alternative or clarifying viewpoint that the reader can seek out to suit his or her own interest in the topic. This review does not appraise all available research that may be relevant to a particular topic, but it does attempt to focus on key points and findings while citing numerous additional identified published studies in an extensive web-only Refer- ence section (Appendix D), plus a web-only Bibliography (Appendix E) of citations that are useful, but not directly cited in the text. This narrative presents an overview and some discussion of previous experimental and analytical works, selected because they explain effects of psychoactive chemicals (drugs, medications, supplements, and so on) on operator performance, particularly drug effects on psychomotor tracking, reaction time, judgment, and decision-making performanceâall directly related to driving performance. The review suggests current gaps in knowledge on these topics. The information contained in the review can assist in developing a rationale for proposing new research that still remains to be accomplished. It also may be used to scope the types of interventions avail- able to be included in more thorough analyses of the issues raised in the problem statements described earlier. Bibliography of References Cited and Additional Literature During the extensive search for, review, and critique of numerous scientific references for this synthesis, it became apparent that a great number of reports on psychoactive drugs and chemicals and performance are available (some previous review articles examined cite dozens, even hundreds of studies). Many of the reports identified here appear directly related to the task at hand, whereas many others only provide additional background or are only tangentially related. In both cases, the articles and reports are widely scattered. The references (web-only Appendix D) contain all of those citations actually cited in this report. It was deemed appropriate to provide at least a bibliographic listing of related citations in the belief that presenting them together in a single listing might save other researchers significant search time when
5looking for additional publications pertinent to these topics. The Bibliography (web-only Appendix E) lists those citations determined to be sufficiently related to effects of psycho- active substances on performance and health to warrant including, that are not specifically mentioned in the text, but that could provide additional background. Survey of Medical Examiners Performing Commercial Driver Medical Examinations The synthesis team distributed a survey questionnaire about medications and drugs to a small convenience sample of 23 medical providers who administer CDMEs to commer- cial drivers seeking medical qualification and certification to drive commercial vehicles. The questionnaire was administered in two western geographical regions of the United States: 15 medical examiner responses were obtained in a Salt Lake City, Utah, survey; and 8 medical examiners were surveyed in Reno, Nevada. The questionnaire asked these medical examiners about: â¢ Their anticipated certification decisions regarding chem- ical substances identified while performing medical qualification exams of CMV drivers, â¢ Their role in providing medical advice about driver alertness and combating fatigue, â¢ Their advice on the use of and identifiable hazards associated with ingesting chemical substances in the workplace, and â¢ Advice they might or might not give to CMV drivers and to their employers. In particular, providers were asked about the certification actions and information resources relied on in making driver certification decisions. The survey questions asked of med- ical examiners also solicited suggestions for improvements in the administration and conduct of occupational medicine and CDME practices concerning use of chemical substances by drivers, and about the health and safety implications attached thereto. A summary of the questionnaire results is presented in chapter six of this synthesis report. Survey of Commercial Carrier Policies on Driver Use of Chemical Substances A structured interview questionnaire for use by CMV stake- holders (predominately truck carrier fleet managers, safety advocates, and other company officials) was administered to elicit key information about current policies, applications, and programs involving the use, or restriction of use, of psychoactive chemical substances by commercial drivers. The survey questionnaire asked specific questions about fleet managersâ knowledge base, and about current company policies regarding driver use of stimulants, hypnotics, and nutritional supplements. The survey was sufficiently open- ended to gather information about experiences with current approaches, procedures, and safety policies in place, to identify problems, and to elicit proposed solutions regarding the use of chemical substances in the commercial transportation industries. Survey questions were specifically designed to cover the scope and objectives outlined previously. The survey questionnaire for motor carrier company officials was distributed by members of the American Transportation Research Institute (ATRI) to (1) the American Trucking Associations (ATA) Safety and Loss Prevention Management Council, (2) a Health and Wellness working group within that council, and (3) several wellness clinics located at travel centers that target over-the-road drivers. The participants consisted of safety and human resource personnel within the trucking industry, including motor carriers and allied profes- sionals (e.g., motorcoach companies and health and wellness clinics). Motor carrier representatives were invited to partic- ipate by e-mail, which included an Internet link on ATRIâs website where respondents could gain access to the online version of the Chemical Effects Survey. There were 31 company responses. These companies employed a range of from 10 to a maximum of 6,200 drivers, with a company average of more than 800 drivers. Most respondents were truck carrier firms. The survey also netted responses from one commercial driver training company and one charter bus company. The specific questions posed in the survey are depicted in the context of the presentation of the results along with summary statistics for the surveys, and are described in chapter seven of this report.