The Scope of Occupational and Environmental Health

The specialties of occupational and environmental medicine deal with health issues that relate to exposures in occupational (work) settings and/or are due to contact with environmental factors, conditions, and changes. The occurrence of occupational and industrial diseases is estimated to be approximately 900,000 illness cases per year with a broad spectrum of manifestations. However, these occupational diseases continue to be under-recognized. The focus is the environmental determinants of noninfectious diseases in the workplace and non-occupational environmental exposures resulting in disease.

Examples of issues included in this focus are:

Increased cancer risk from radon in indoor air; Neurological dysfunction from exposure to lead in house dust and drinking water; The consequences of measurable body burdens of halogenated organic compounds (dioxin, PCBs); The possible neurotoxic and carcinogenic effects of food additives; The health effects of global warming and ozone depletion; and Epidemic and pandemic implications of infectious diseases (HIV/AIDS, Tuberculosis, Hanta Virus, Ebola Virus, West Nile Encephalitis Virus, Mad Cow Disease).

The responsibilities of the healthcare and safety professions are to raise the level of suspicion for workplace disease, develop skills in taking occupational and environmental exposure histories, and establish routine access to occupational health resources.

Occupational and environmental medicine is defined operationally by the following principles:

The expression of most environmentally caused diseases is the same as those of non-environmental origin. Many diseases of occupational or environmental cause are multi-factorial. The effects of occupational and environmental exposures occur after a latent period interval following an exposure. The dose of an exposure to an agent is a strong predictor of the likelihood and type of effect. Host variability, the substantially different response(s) by organisms of the same species (for example humans) to the same exposures, is a significant factor.

Occupational and industrial problems encompass both occupational injuries and occupational diseases. The occupational diseases can have environmental determinants, be non-infectious in origin, be exposure driven, and have components of risk due to the susceptibilities of the host. The magnitude of their consequences is underscored by the following statements.

1) Quantifying risk levels due to environmental exposures in a given population presents major methodology difficulties. 2) According to the Environmental Protection Agency (EPA) Indoor Air Quality (IAQ) is one of the top five health risks in the United States today. 3) It is estimated that 75% of cancers in the United States are avoidable, and are largely due to environmental factors.

The core disciplines involved include safety, healthcare and medicine, public health, toxicology, epidemiology, and industrial hygiene. Toxicology is the study of the adverse effects of substances on living organisms, and the assessment of the probability of their occurrence. Of note is the concept of the dose-response relationship. This concept was framed in the 15th century by Paracelsus in his statement, “All substances are poisons; there is none which is not. Only the dose differentiates a poison from a remedy.” The effect(s) on the organism result from the factors of bio-availability (the amount of active material in the exposure medium that can result in an effect), absorption (the process by which the active material enters the tissue of the organism or contacts the surface and penetrates the organism), distribution (the spread of the absorbed material to target-effect sites), bio-transformation (the mechanisms and the rate of these processes that transform the material to a less or non-toxic form or into products that are themselves toxic to the organism), and elimination (removal from the organism). Epidemiology is the systematic method of identifying hazards and quantifying the magnitude of risk. It evaluates the patterns of occurrence of a phenomenon across a population such as a disease across the human population. Such studies can be complex and therefore require great care in data collection and interpretation. They depend on quality of the data, reliability of the methodology, and validity of the interpretation. Industrial hygiene is the health profession devoted to the recognition, evaluation, and control of environmental standards.

Human Impacts

It is necessary to determine if any associations exist between the agent (material) and the disease. Using an epidemiological study as a tool for drawing conclusions about causation once the agent is recognized, allows for the role of the agent (contributing, inciting, and/or sustaining) to be categorized. At times several agents contribute in concert to the outcome for the organism, whereas individually they do not result in the effect. This is called synergism of agents. The role of the host is a major contributor to the result and the contributions played by host variability, host defense mechanisms, and host susceptibilities are vital factors.

Human exposure to agents can occur in, around, and passing through a specific environment. Those functioning around an exposure environment may become at-risk due to prolonged small dose exposure to an agent. Materials can be carried out of the exposure environment on clothing and on the body itself, into environments where others (family members) can become exposed. Adverse responses to these materials include: irritative manifestations, allergic reactions, acute and chronic toxicity including death, and carcinogenicity (the development of malignant tumors, cancer). Specific pollutants occurring in both indoor and outdoor environments are of major concern and include chemicals, cleansers, fumigants, biological/microbial infectious agents and contaminants, and hazardous substances. Environmental design and control: furnishings; occupant activities; HVAC (heating, ventilating, and air conditioning) design, operation, and maintenance; house keeping practices; pesticide applications; and physical-structural impacts, all play significant roles in the extent and degree of exposure.

The various types of biological infectious and contaminant agents are listed in Table 2 along with their potential roles that can affect a host.

Table 2. Biological Agents

Pollen: allergens, irritation Bacteria: infection, toxins Molds/Fungi: allergens, mycotoxins, infection Viruses: infection

Some molds/fungi can be hazardous. They produce spores and mycotoxins. Mycotoxins cause allergic responses by sensitization and spores can cause: Organic Dust Toxic Syndrome (ODTS), hypersensitivity pneumonitis, asthma, allergic rhinitis, and pulmonary mycosis (invasive fungal infection of the lungs). Mycotoxin target organs include: lung, liver, kidney, skin, mucus membranes, eyes, nose, sinuses, base of the brain irritation, gastrointestinal tract, and mycotoxins can be carcinogenic. Fungi of concern include: Cryptostroma, Fusarium (mycotoxin associated with flu-like symptoms), Mucor, Stachybotrys (mycotoxin associated with flu-like symptoms), and Aspergillus. Molds/fungi breed in stagnant water in air conditioning ducts, drain pans, humidifiers, ceiling tiles, carpeting, and insulation. In considering models of environmental exposure (residential and occupational), disorders associated with indoor buildings have been the subject of recent concern by workers, residential building occupants, the insurance industry, and the legal profession in the litigation arena. Sick Building Syndrome (SBS) is an acute condition of office workers with no specific cause resulting from exposure to chemicals released and which become concentrated in the air due primarily to low ventilation rates. Symptoms include irritation of mucus membranes, dry or itchy skin, headache, dizziness, lethargy, fatigue, nausea, and sensitivity to odors. Building Related Illnesses (BRI) are acute exposure conditions with specifically defined causes. Volatile Organic Compounds (VOCs) are exposures to defined chemicals released from synthetic materials such as office products, furniture, building materials (formaldehyde released from wood products and foam insulation). The chemicals released become concentrated due to low ventilation rates. Outdoor sources can contribute through the entry of outdoor air, vehicle exhaust pollutants, malfunction of plumbing vents, and other nearby sources of contamination.

Evaluating the Impact

The goals of any diagnostic and therapeutic strategies are: to identify the cause(s) along with any relationship(s) of the disease to the occupational or residential environment; to develop a plan and institute approaches that will result in reversal, reduction, and/or amelioration of the resulting problem(s); and to prevent any recurrence. The basic mechanisms available to accomplish these goals include:

the history of the structure and the environment; the history of the exposed and affected individual(s); examination; laboratory and confirmatory evaluations; therapeutic interventions; and remediation.

The important considerations defined by the history are presented in Table 3.

Table 3. Historical Considerations About the Affected Individual

Lifetime work/employment/job information Military information Exposures   Type, odors, visible growth Dose Location Temporal relationship of symptoms/signs to the specific environment with decrease and/or resolution when out of that environment Symptoms among co-workers, contacts, family, or others Non-occupational exposures   Home Hobbies Recreational Activities Recurrence – seasonal, temperature, humidity changes Manifestations related to biological agents –   rhinitis, nasal congestion, pharangitis, cough, wheezing, asthma, dyspnea, lung disease, conjunctival irritation, headache, dizziness, lethargy, fatigue, malaise, nausea, vomiting, anorexia, cognitive impairment, personality changes, rash, fever, chills, myalgia

A similar specific evaluation employing the mechanisms defined above is necessary to evaluate the exposure environment and the structure.

Laboratory and confirmatory evaluations as defined in Table 4 are important before instituting any therapeutic and prevention interventions.

 

Table 4. Laboratory and Confirmatory Considerations

Quantitative Immunoglobulins: IgG, IgM, IgD, IgE RAST (Radioallergosorbent Testing) – blood serum is against relevant antigens Skin Testing Nasal Smear for Eosinophils Pulmonary Function Testing (PFTs) Bronchoprovacative Testing Chest X-Rays Complete Blood Count (CBC) with Differential Count, Total Eosinophil Count Fungal Antibodies Skin Biopsy

Therapeutic and Prevention Strategies

Treatment must be applied to the structures and the environments as it is to the affected organisms/humans/hosts. This treatment approach must include symptomatic relief, disease control, a plan for appropriate corrective actions, remediation, and occupant protection.

Prevention is guided by the practical admonition, “Pay Now or Pay Later.” It embodies education, communication, exposure control, and environmental observation (case identification, trend monitoring, health effects surveillance, and hazard surveillance). It necessitates educational outreach to create understanding of the bio-environmental issues and their consequences by healthcare providers, industrial health and safety directors, environmental specialists, insurance company executives and adjusters, government officials and lawmakers, and attorneys. Insurance companies should be educated to understand the subtleties of multi-faceted and specialized claims related to the spectrum of bio-environmental problems. Attorneys and judges require education to understand the complex technical and scientific issues involved. It is of paramount importance to develop community understanding of these factors. Community awareness and education utilizing materials that are educationally sound and effective is a societal imperative for the twenty-first century.

Responsible planning needs to be initiated and incorporate constructive approaches such as The Health of Structures^©. This concept is a positive approach requiring a team effort involving varying disciplines (healthcare professionals, toxicologists, epidemiologists, biologists, industrial hygienists, engineers, architects, builders, renovators, remediators, planners, regulators, government, insurance professionals, and legal professionals) with their varying priorities, who must be educated to appreciate and respond to these major public health issues. The varying languages of these disciplines must reach out for common meaning and understanding that leads to common direction and purpose.

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