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Chapter 2: Human Exposure to Chemicals
Human Health Risk Assessment study cards Baylor University
20
Environmental Studies
Undergraduate 4
02/27/2013

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Term
Most susceptible contact sites and target organs
Definition
MAJOR ROUTES
1. skin --> percutaneous
2. lungs --> respiratory
3. mouth --> digestive

MINOR ROUTES
1. rectal
2. vaginal
3. parental
Term
Crucial physiological elements to the study of human exposure to chemicals
Definition
1. skin
2. vascular system
3. respiratory system
4. digestive system
5. circulatory system
6. liver
7. kidneys
Term
skin
Definition
--highly organized
--serves as a protective barrier
--dynamic living tissue whose pemeability may change
--stratum corneum major barrier to absorption
--permeability coefficient (Kp) key in estimating dermal absorption
Term
vascular system
Definition
--represents the blood stream
--distributor of absorbed chemicals
--to become part of circulation, a contaminant must penetrate to the dermis
Term
respiratory system
Definition
--prime site for absorption and distribution
--inhaled air enters the lungs and encounters a huge area of tissue that allows exchange of gas in the lungs with gas in the blood
--suspended particles present a unique problem in that they tend to collect on the bronchial tubes and interfere with gas exchanges
Term
digestive system
Definition
--absorption occurs in the stomach and intestines (most important is the small intestine)
--can have some absorption in the stomach, but mostly in the small intestine
--large intestine stores undigested/unaborbed food for excretion later
Term
circulatory system
Definition
--distribution and removal of chemicals after absorption
--very important route of distribution
--the human body contains 3-6 liters of blood (adults typically have 5-6 liters)
Term
liver
Definition
--filter for blood
--control system for levels of chemicals
--place where toxic substances can be transformed via detoxification reactions
--most important in facilitating chemical transformations
Term
kidneys
Definition
--blood passing through deposits substances not needed by the body
--these are generally separated and excreted in the urine
--kidney facilitates excretion from the body
Term
target organ toxicity
Definition
1. hematotoxicity (blood cell toxicity)
2. hepatotoxicity (toxic effects in the liver)
3. nephrotoxicity (toxic effects in the kidney)
4. neurotoxicity (toxic effects to the nervous system)
5. dermatotoxicity (adverse effects produced by toxicants in the skin)
6. pulmonotoxicity (disease states in the respiratory system resulting from inhalation of toxicants
Term
Inhalation exposures
Definition
--indoor air (volatile constituents and fugitive dust)
--outdoor air (volatile constituents and fugitive dust)
Term
ingestion exposures
Definition
--drinking water, swimming, soil ingestion, crop consumption, dairy and meat consumption, seafood consumption
Term
dermal exposures
Definition
--showering, swimming, soil contact
Term
airborne chemical toxicants
Definition
--can travel great distances (DDT in beluga whales in the Arctic)
--chemical concentrations are a combination of ground-level concentration and dilution factor
--some contaminants have a direct effect on the body's ability to transport oxygen
Term
chemicals in water
Definition
--surface water contamination given high priority early on
--groundwater contamination is the "hidden" pollution problem
--another "hidden" water problem is eutrophication
Term
chemicals on land
Definition
--contamination in soils can impact several other environmental matrices (migration, volatilization, runoff)
--exposures via direct inhalation of vapors or respirable particles, dermal absorption, ingestion, food chain (crops grown in contaminated soils, grazing activities, dairy), leaching into waterways, uptake in aquatic organisms
Term
chemicals in food
Definition
--major source of human exposure to chemicals
--dietary exposures are a function of consumption and chemical concentration
--complex to estimate chemical amounts in food
Term
public health and socio-economic implications
Definition
--potential exposures are enough for public outcry
--reduction of life expectancy
--reduced quality of life
--averted by carefully implementing risk management strategies or corrective action
Term
General nature of human health effects
Definition
MAJOR CATEGORIES
1. carcinogenicity
2. genetic and chromosomal mutation (heritable)
3. developmental toxicity and teratogenesis
4. reproductive toxicity
5. neurotoxicity
6. alterations of immunobiological homeostasis
7. congenital abnormalities
Term
assessing public health risks
Definition
1. problem definition
2. identification of the principal hazards
3. design of sampling and analysis programs
4. collection or reporting lab results for further evaluation
5. analysis of results
6. interpretation
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