Astatkie Zikarge, MD, MPH, Environmental Health, Texas Southern University, College of Pharmacy and Health Sciences, 3100 Cleburne, Houston, TX 77004, 7133137231, zikarge_ax@tsu.edu

We live in a complex world of potentially hazardous chemicals where the risk of exposure is determined by lifestyle, occupation, and individual susceptibility. Today’s medical care has shifted towards a risk-based holistic approach following the public health paradigm of disease prevention, health promotion /maintenance, environmental protection and surveillance. Exposure assessment is a significant part of the overall risk assessment and management strategy along with hazard identification, risk characterization, dose-response assessment, risk communication, perception and management. General medical practitioners neither have the time nor the necessary discipline to undertake a comprehensive exposure history of their patients. As a result many chronic diseases go undiagnosed or improperly treated. This presentation is designed to help practitioners develop the habit of assessing exposure history routinely to avoid these pitfalls. Environmental exposure assessment is a systematic process of estimation of the magnitude, frequency, duration, and route of exposure to environmental hazards as well as the size and nature of the affected population. The environments from where risks originate can be conveniently classified as residential, occupational, recreational, ambient, outer space or exotic. Each environmental entity poses a special exposure issue to be considered. Only the occupational environment is more fully regulated by exposure standards while partial regulation is in effect over the air, water, and food environments. The remaining sources are completely unregulated and have increasingly become major concerns of exposure. In the same way, exposure agents are traditionally classified as heavy metals, organic solvents, pesticides/herbicides and radionuclides. Among them, environmental lead, radon, endocrine disruptors, metal fumes and organic vapors are major concerns. Unique patterns of toxidromes of each class are helpful in risk estimation. Inhalation, percutaneous absorption, and ingestion (in this order) are major routes of environmental exposure. The major target organs affected are, therefore, the respiratory tract, the skin, and the enterohepatic system. Toxicants, which enter the general circulation after biotransformation, may pose special concerns to the nervous system, the immune system and the urogenital tract. Organ specific mutagenesis, carcinogenesis, and teratogenesis can also be adverse outcomes of environmental exposure. Estimation of risk is a difficult task largely because no one individual is confined to a single environment, nor to a single agent or concentration. Exposure is often to a mixture of compounds in small doses over a long period of time. This situation may allow interaction of the agents within the host additively, synergistically, or antagonistically. The host may also detoxify and neutralize the agents or repair the subsequent damage. The host may also show extreme sensitivity to the smallest concentration of the agent based on its antigenic, enzymatic, or chromosomal polymorphism. In addition to environmental monitoring, increasingly biomarkers of exposure, response/effect and susceptibility are exploited in clinical medicine to qualitatively and quantitatively assess the exposure specificity, sensitivity, burden, and predicative value of these parameters. Physicians should constantly seek understanding of how these resources can be applied to his/her clinical practice to increase his/her skills of exposure assessment. All health care practitioners should also be aware of the larger environmental issues of today within which exposure occurs including but not limited to the green house effect, stratospheric ozone layer depletion, acid precipitation, and photochemical smog.

Learning Objectives: This presentation is intended to provide participants with an increased awareness of the contribution of environmental exposure to disease causation or exasperation of pre-existing medical conditions. Taking an exposure history is an extended part of the comprehensive medical diagnostic strategy for which an average busy practitioner neither has the time nor the discipline to undertake. The major objective of this presentation is, therefore, to help the medical practitioner develop a habit of taking a thorough environmental exposure history and put a multidimensional perspective to his/her patient’s illness. This is the way Ramazzini, the father of environmental/occupational medicine, intended it, modern preventive medicine demands it, and is a prudent approach to holistic patient care. At the end of the presentation, participants are expected to

• Define the terms risk, hazard, and toxicity.
• Recognize the systematic risk assessment/management paradigm.
• Identify the major environments of concern and organize the potential exposure hazards
• Distinguish the major routes of exposure and target organs of response.
• Assemble major illnesses primarily related to environmental exposure.
• Identify susceptible segments of a population to specific exposures.
• Exploit and determine the appropriate biomarkers of exposure, response or susceptibility
• Estimate the exposure risk from industrial hygiene or environmental surveillance data.
• Relate exposure risk to exposure standards and compute margin of safety. 1
• Appraise global environmental issues impacted by human activities.

Keywords: Environmental Exposures,

Presenting author's disclosure statement:
I do not have any significant financial interest/arrangement or affiliation with any organization/institution whose products or services are being discussed in this session.