Aims of Total Exposure Health

True prevention will be achieved when all relevant exposures are measured and controlled, regardless of where they occur, and sensitive or genetically at-risk subpopulations are provided exposure limits that protect them. TEH provides the new framework to use the technological and medical advancements and apply them to the exposure science that IHs and EHS practice. There are no other professions specifically bringing these formerly disparate science professions together. IHs and EHS are in the ideal professions to bring the data from these disciplines together and apply them in practice. IHs already use the data from all these sciences to apply exposure limits to humans, and they serve a large percentage of the exposed population, the workers, regularly. With the risk to relevancy looming as fewer workers are exposed and fewer are exposed above exposure limits, it becomes increasingly important to provide exposure-based disease prevention to those individuals at risk due to increased sensitivity wherever exposed and whether or not they are workers.

The Totals Explained

The terms Total, Worker, Exposure, and Health are often heard in various combinations: Total Worker Health® (TWH), Total Worker Exposure (TWE), and TEH are the three most interrelated and confused in the practice of IH today. Each of these totals has overlapping areas of concern which is the primary reason there is confusion. The key to describing the differences is to think of the population which is covered by the term, the exposures that are covered by the term and, finally, the preventive health practices which are incorporated into the definition.

Total Worker Health®

Chapter 4 of this volume by Tamers et al. provides a comprehensive review of TWH and contains a figure that lists the issues relevant to TWH from the National Institute for Occupational Safety and Health (NIOSH) of the Centers for Disease Control and Prevention (CDC). NIOSH defines Total Worker Health® (TWH) as policies, programs, and practices that integrate protection from work-related safety and health hazards with promotion of injury and illness prevention efforts to advance worker well-being (NIOSH 2015). The most important consideration from an exposure standpoint is that TWH needs IHs and EHS who are participating in the process to define which exposures are included. The limitations imposed by TWH only

TABLE 1.1

Areas of Concern—TWH

require the exposures to impact workers. This then allows for and expects exposures that occur external to the workplace under the “Built Environmental Supports” and “Community Supports” categories, namely healthy community design, healthy housing, safe and clean environment, and quality healthcare. TWH does not specifically or separately categorize precision medicine, but under the quality healthcare category, the practice of medicine is increasingly adding precision health to medical care. Precision health, which includes genomic health, is also covered later in this volume in the “Advances in Toxicology” section, and the quickly expanding scientific fields identified as “-omics” are becoming increasingly important to the professional community seeking to provide quality healthcare. TWH does not cover non-workers in its definition but does cover psychosocial factors to provide flexible work arrangements such as working from home, work-life programs, housing, green spaces, productive aging, and health information privacy which are all significant parts of the non-work environment and have exposure aspects. See Table 1.1.

Total Worker Exposure (TWE)

Originally coined by the American Industrial Hygiene Association (AIHA; www. aiha.org), TWE was established as a content priority (i.e., focus area) of AIHA. There is not much formally written about TWE, but it is used in both the TWH and IH communities. TWE takes the classic at-work exposure concerns, which IHs have seen as part of the application of industrial hygiene, and adds the exposures to the worker primarily from the environment and from work not associated with the primary employer. See Table 1.2. In a TWE delivery model of IH, the IH professional takes special care to identify and include exposures that occur during the working day but not from the work itself (the at-work environment). Some examples of these types of exposures are personal smoking, chemical exposures from ambient air when there is infiltration from a waste plume under a slab at a workplace, airborne exposures from nearby industrial operations, radiation from natural sources such as the

TABLE 1.2

Areas of Concern—TWE

sun and radon, ingestion exposures from water sources, and hand-to-mouth environmental contamination transfer. TWE also considers exposures that are received from multiemployer individuals who receive exposures from the multiple jobs they hold. TWE could include exposures in an alternative work environment such as a home office worker or a worker without an office such as a truck driver or a salesperson. For these workers, TWE attempts to capitalize on the increased availability (lower cost, ease of collections, etc.) of sensors to gain exposure data on these alternative work environments. Just as in TWH, it is important to understand what TWE does not specifically include. First, it does not include exposures from locations that are not at a workplace; therefore, it only covers the workforce but not other members of society. TWE gathers exposure data and then applies an exposure profile of all related work exposures to the standard exposure limits established using population- based statistics commonly referred to as occupational exposure limits (OELs).

Total Exposure Health(TEH)

TEH considers exposure from four primary areas: Occupational, Environmental, Lifestyle, and Clinical (Figure 1.1). TEH does not limit its use to workers alone, although workers do comprise a significant portion of the population which benefits. IHs often find themselves applying their exposure collection and knowledge in environmental and community exposure positions and work closely with EHS. This is because the knowledge needed to be a good IH exposure scientist is nearly the

FIGURE 1.1 Exposures relevant to TEH.

TABLE 1.3

Areas of Concern—TEH

same as being an environmental or community exposure scientist, e.g., EHS. The differences are in a few sampling methods and the way the laws treat the exposures from a regulatory standpoint. The TEH framework acknowledges this skill and envisions its use to combine the workplace environmental exposures and work exposures together for the worker (like in TWE). Likewise, IHs have the expertise to collect and assess exposures from the full environment, a person’s lifestyles (at home and hobbies), and clinical exposures and adds these when at relevant levels to impact prevention of disease. TEH likewise addresses the need to capture exposures for the non-working population similar to how community health and EH communities apply exposure science to a community, but TEH then adds in exposures from lifestyle (home and hobby) and clinical testing and treatment (Table 1.3). Finally, TEH considers individual proclivity to disease when possible. Genetically, every human is different and has the potential to respond differently to an exposure. Present guidelines do not account for this genetic predisposition but instead use population-based limits to protect the majority population which potentially overprotect one population subset and underprotect another population subset. TEH, therefore, of the three frameworks includes the greatest population set, the greatest exposure set and acknowledges and uses the latest medical understanding of individuality and precision medicine to deliver true primary prevention.

TEH Exposures of Concern

It is a common misunderstanding that under TEH, every exposure must be identified. While this would certainly be the optimum, it is not possible. Total exposure, therefore, represents as many exposures as can be identified and have the potential to be relevant. Relevancy, as mentioned earlier, can be because they are additive to other exposures and this total must be considered. Relevancy also considers exposures which may be more concerning at low levels for an individual but not for a population overall. IHs and EHS already consider some of these relative exposures such as exposure concerns for breastfeeding mothers and mothers to be, individuals with compromised or reduced organ function (e.g., liver or lung), and/or individuals with a chemical hypersensitivity (e.g., formaldehyde or isocyanates). Relevant exposures not currently addressed by the practicing IH and EHS are genetic predisposition or proclivity to negative effects from an exposure.

The different exposures which can be part of the total may or may not be easily obtained and readily available. Those easy to obtain can, of course, still be used. For the exposures which are more difficult to obtain, new tools and techniques are being developed, and the IH and EHS communities need to recognize and be ready to use these new sources. Another chapter in this volume discusses silicone wristbands as just one example of a new tool available to gather exposures. These wristbands collect volatile organic chemicals at a low cost and deliver a simplified way to measure exposures at multiple time intervals. One interval can be selected as the workday, and another interval can record non-working hours and easily provide a total exposure for a large number of organic chemicals. The practicing IH and EHS may not readily imagine all the exposures which occur and should be considered in TEH. To begin to appreciate the expanded possibilities that are becoming available, each of the four primary exposure areas is now discussed in detail.

Occupational

TEH as a framework includes all the current IH exposure practices and uses the established exposure limits and associated regulatory standards. For more information, Chapter 5 by Yamamoto provides a comprehensive review of current IH exposure practices. TEH acknowledges and expects the use of regulated standards since there need to be guidelines employers can follow to know that the population of workers under their management are being taken care of to a recognized standard. Using recognized minimum standards for SEGs is still possible. However, with the desire to move toward more personalized medicine and with the increased ability to collect exposure data with smaller, cheaper, and more easily used sensors, the TEH framework that provides individual exposures is preferred. Exposures for at-home workers are not likely to be from their actual work processes, so these exposures would be captured under a different category. Exposures from work at a second employer may be available if the second employer has a quality IH program. Often the secondary forms of employment do not have this type of monitoring, and in these cases, these exposures are best handled as exposures based on lifestyle.

Environment

Environmental exposures occur all the time. An individual experiences environmental exposure simply by being present in a particular environment. Common environmental exposures are chemicals in drinking water, ambient air with the potential to have waste products or naturally occurring chemicals (РМЮ, PM2.5, ozone, mercury, etc.), solar radiation, and naturally occurring radioactive materials (radon). Less common environmental exposures can be infiltration of a living or working space’s air from an underground chemical plume, pesticide, or fungicide overspray from farming operations, naturally occurring hazardous materials like asbestos deposits, heavy metal-laden soils (ingestion or inhalation), noise from nearby aircraft operations, traffic corridor and traffic congestion exposures, and many more. These exposures can be identified in several ways. The EHS in the EH community collects data on many exposures of concern, and these are documented and published. The IH can get this data from the internet easily and apply it to an individual. The specific quantification of exposure is not available through these data sources, but estimates are possible. If the exposure is relevant, then specific testing can be done to measure an individual’s exposure.

Lifestyle

Lifestyle exposures include exposures that apply to people due to the specific aspects of their living situations and the hobbies or activities they choose. Many lifestyle exposures can approach exposure levels which would be experienced in an occupational setting. For example, some hobbies which have noise exposure in excess of the exposure limits are attending concerts, listening to music with headphones, playing an instrument, volunteering as a firefighter, going to a bar, and flying a private plane. Hobbies involving vehicles and engines such as engine repair, car racing, motorcycle riding, and car restoration can have noise and vibration issues. Artistic hobbies such as spray paint art which uses volatile organic compounds (VOCs), woodworking which generates dust and VOCs, and stained-glass art which can cause ingestion of lead from hand-to-mouth contact all can have exposures of concern.

Secondary jobs can have exposures of concern such as noise for bartenders and musicians, chemicals from farm jobs, and radiation and biological hazards in medical positions. Finally, exposures can be from lifestyle choices. Some examples of these types of exposures are noise and exhaust gases from a long and congested commute, noise from mowing a large yard or caring for a crying baby, gardening which increases exposure to solar radiation, usage of pesticides and herbicides, and maintenance of a household with potentially toxic chemicals. These exposures may or may not exceed an exposure limit on their own, but they definitely add to the overall daily exposure. An IH can be practicing TEH if he or she asks about these types of exposures and considers them when applying the exposure limits. The IH can go beyond present recognized exposure guidelines with more targeted questioning of individual choices, collect some exposure data to quantify the additional exposures, and consider the additional exposures when applying controls. The important thing is not to ignore these exposures as they can be significant.

Clinical

Clinical exposures are often completely ignored by practicing IHs. There are a number of reasons why this occurs. The first reason is privacy. Under the Health Insurance Portability and Accountability Act (HIPAA), medical information is private and releasable only when specific permission is given by the individual whom the information is about and there is a medical need. While there can be a medical need from an exposure standpoint, IHs are not connected well to the medical community other than through the occupational health function. While the health community has the needed information, it is reasonable for the IH to feel the wall of privacy prevents him or her from having any information. The second primary reason clinical exposures are ignored is that clinical testing to provide medical care is considered a fact-of-life and of limited duration and not taking place at work anyway. Therefore, under normal IH practice, a worker regularly monitored for ionizing radiation exposure receives a clinically necessary medical X-ray without any concern about the additive exposure.

Pharmaceuticals also represent a clinical exposure, and these are more likely to be longer term or ongoing. Pharmaceuticals, by their very design, are bioactive.

Drugs can impact the organ functions of the kidneys and liver which are key to detoxifying and eliminating chemicals that enter the body. There are hundreds of drugs with ototoxic properties that encompass nearly every drug class (Bisht and Bist 2011) and can be a cause of hearing loss beyond noise-induced hearing loss (NIHL). For these exposures, the IH community needs to work with the medical community to ensure that the standards being developed for innovative medicine, such as electronic health records, can integrate clinical and nonclinical exposures to inform the conversation between patient and provider and provide recommended practices to protect the patient.

The onset of pregnancy is a good example of a present integration where informed dialogue is beneficial; a provider tells a patient there are special actions that should be taken to protect the health of the baby. The patient now in TEH terms is a member of society who chooses to reduce personal exposures, such as limiting her alcohol intake, and has the option to inform her employer and ask for additional monitoring or altered work or additional protections to decrease the risks to the pregnancy.