EAYH Lecture 4 Sept 8 - EAYH Lecture 4 General Aspects of...

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EAYH Lecture 4 9/8/11 General Aspects of Environmental Exposures and Epidemiology Environmental Exposure Exposure: any condition which provides an opportunity for an external environmental agent to enter the body through various transport mechanisms Distinction between exposure and dose exposure is “outside” the body. POTENTIAL for things to enter the body. dose is “inside” the body. Amount/concentration once it gets inside. Vectors for Exposure vs. Route of Exposure air (via lungs) food (via GI tract) soil (via GI tract and skin) water (via GI tract and skin) Exposure Parameters Time acute (short period of time) vs. chronic (long period of time) more concerned about low dose, chronic exposures to harm human health Location outdoors vs. indoors vector route air-inhalation water/food – ingestion soil-dermal; ingestion Exposure studies reveal that people come into contact with toxic volatile organic compounds and pesticides more indoors than outside . Most people's exposure to breathable particles during the day is higher than ambient levels in the air (either indoors or outside), because moving about stirs up a “personal cloud.” – Scientific American National Report on Human Exposure to Environmental Chemicals (CDC) NHANES-- taking blood samples of people throughout the country to figure out: Are exposure levels increasing or decreasing over time? Are public health efforts to reduce exposure working? Do certain groups of people have higher levels of exposure than other groups? Issues in Understanding “Exposure” Distinction between agents and vectors agents are what is in vectors (chemicals, etc.) Time activity patterns what did the agent do in environment with time? What is it's behavior? What did host do in environment with time?
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The host is PEOPLE. What activities did you do? Homogeneous vs heterogeneous exposures mixed exposure scenario makes it difficult to quantitate putative agent – hard to determine exactly what people were exposed to Factors influencing biodistribution – once it gets inside of us, we all handle exposures differently same exposure may not yield the same dose Exposure Assessment Characterization of exposure setting Identification of exposure pathway ( vector ) Quantification of exposure measurement outside body, measurement of how much enters body, etc. exposure = intensity x frequency x duration Assessing Exposure and Health: The Science of Quantifying this Relationship Exposure Assessment: the quantification of human engagement with environmental contaminants Why do it? To evaluate the potential relationship between exposure to the environmental
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EAYH Lecture 4 Sept 8 - EAYH Lecture 4 General Aspects of...

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