ingestion handout gfa
TRANSCRIPT
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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.