Ingestion Handout GFA

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    Ingestion

    Exposure

    G. Armecin

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    Learning Objectives

    Learn the basic physiology of the

    gastrointestinal tract

    Transport mechanisms

    Describe the various pathways of ingestionexposures and selected contaminants

    Dietary ingestion water and food

    Non-dietary ingestion

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    Gastrointestinal Tract: Physiology

    What are the parts of the GI tract?

    What are the phases of regulation

    of GI tract?

    How does the GI tract absorbednutrients and

    other materials?

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    Gastrointestinal Tract: Physiology

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    Gastrointestinal Tract: Physiology

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    Gastrointestinal Tract: Physiology

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    Gastrointestinal Tract: Physiology

    Epithelial Layer: GI tractEpithelial Layer: Skin

    Epithelial Layer: Respiratory tract

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    Gastrointestinal Tract: Physiology

    LumenEpithelium of small intestine

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    Gastrointestinal Tract: Physiology

    Goblet cell

    Epithelial cell

    Capillaries

    Lacteal

    Vein

    Artery

    Lamina propria

    Nerve

    Villi of the Small Intestine

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    Transport Mechanisms

    Lets watch this:

    http://www.youtube.com/watch?v=kfy92hdaAH0&feature=related

    Active transport Passive transport

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    Water and Food Ingestion

    Humans ingest between 0.9-2.1 L of water and

    within 0.5-1.25 kg of food per day

    USEPA (1997) suggests using 2 L/day and 1 kg/daywhen modeling human exposure to drinking water

    and food intake, respectively

    Can you identify contaminants that we can beexposed through water and/or food ingestion?

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    Contaminants in Water and Food

    Biological Contaminants Bacteria, Viruses, Parasites, Protozoans

    Chemical Contaminants Pesticides

    Organosphosphates

    Atrazine

    Metals Calcium chloride

    Lead

    Arsenic

    Mercury

    Cadmium

    Copper

    VOCs Trihalomethanes (THM), Trichloroethance (TCE) and Tetrachloroethylene

    (PERC)

    Organic compounds PCBs, PCDEs, Phthalates

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    Health Effects of Dietary Contaminants

    Contaminant Health Effects

    Bacteria Vibrio cholerae (cholera), E. coli (diarrhea)

    Protozoa Entamoeba hystolytica(diarrhea)

    Parasite E. vermicularis( insomnia, irritability)

    Virus Coronavirus (cough, gastrointestinal symptoms)

    Atrazine Reproductive effects, cancer

    Lead Cognitive development

    Arsenic Anemia, leukopenia, death

    Cadmium Kidney, bone and pulmonary damages

    Mercury Desquamation

    Selenium Endocrine disruption

    VOCs Liver and kidney diseases

    Phthalates Endocrine disruption

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    Maximum Contaminant Limit (USEPA)

    Contaminant MCL Average Daily Dose* Note

    Atrazine 3 ppb < 0.05 g/kg body

    weight/day

    If concentration >1 ppb,

    monitoring program

    should be set up

    Lead 15 ppb < 0.05 g/kg body

    weight/day

    Arsenic 10 ppb < 0.03 g/kg body

    weight/day

    Chloroform

    (THM)

    100 ppb 3 g/kg body weight/day

    TCE 200 ppb 6g/kg body weight/dayPERC 5 ppb 0.2g/kg body weight/dayMetals in food+ < 0.5 g/kg body weight/day

    * assuming 70 kg body weight, 2 L of water/day+ assuming 70 kg body weight, 1 kg food intake/day

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    Non-dietary Ingestion

    The types of non-dietary ingestion are hand-to-mouth, soil

    ingestion, inhalation followed by clearance and swallowing and

    inadvertent ingestion.

    Children are the most at-risk of non-dietary ingestionbecause of their pica behavior.

    In the literature, other high risk groups from inadvertent

    ingestion of chemicals are workers in industrial plants.