ROUTES OF EXPOSURE Flashcards
about _________ chemicals are used worldwide
70,000
chemical industry introduces _____ to ________ new chemicals each year.
200 to 1,000
Trace amounts of toxic chemicals are present in ___
food, air, and drinking water
Exposure to toxic substances occurs through the three major routes
- skin (dermal absorption)
- respiratory tract (inhalation)
- digestive tract (ingestion)
Contact with the skin is the most common path of toxic substance exposure
dermal absorption
outer layer of skin
epidermis
The outermost layer is
stratum corneum (carnified layer)
structure that determines the rate of absorption of substances through the epidermis
stratum corneum (carnified layer)
The inner layer of the skin is sometimes referred to as the ____
true skin
in animal hides, this is the layer that turns to leather when chemically processed
dermis (inner layer)
source of oxygen and of nutrients for the epidermis.
dermis (inner layer)
The hair follicles, sweat glands, and sebaceous (oil) glands are found in this layer
dermis (inner layer)
These structures play a limited role in the absorption of substances across the
skin
dermis (inner layer)
This layer provides a cushion for the underlying structures and allows the skin to move to some extent.
Subcutaneous fatty tissue
factors affecting dermal absorption of toxic substance
condition of skin, chemical make up of substance, increasing concentration of toxic substance or exposure time
effective barrier to absorption of some toxic chemicals
intact stratum corneum (epidermis)
not easily absorbed through intact, healthy skin (such as cadmium, lead,
mercury, and chromium
inorganic chemicals and substance
________dissolved in water do not easily penetrate the skin because the skin is impermeable to water
organic chemicals
easily absorbed through the
epidermis
organic solvents (paint thinner, gasoline)
easiest and fastest means of exposure to toxic substances because toxic substances are readily absorbed in the respiratory tract.
inhalation
the __________ of respiratory tract is NOT effective in preventing absorption of toxic substances into the
body.
lining
The respiratory tract consists of the ____
nasal passages, trachea (windpipe), larynx (voicebox), and lungs.
usually occurs accidentally or unknowingly
ingestion
digestive tract consists of ____
mouth, esophagus (food canal), stomach, intestine (large and small).
affect the absorption of toxic substances
physical and chemical factors
affected because of the structure of the body and the length of time food containing the substance remains in the body
absorption
common point of contact for toxic substances
eye
The primary point of contact for toxic substances is the ____
cornea
The outer layer of the eye is made up of connective tissue called the _____
sclera
middle layer of the eye is called ____
choroid
forms the iris
choroid
innermost layer of eyes that produces images
retina
compartments within the eye contain a fluid-like substance is called ____
aqueous humor
transparent jelly-like substance is called ____
vitreous humor
All nutrients and oxygen must diffuse through the _____in the back of cornea to repair the damaged tissue.
aqueous humor
into a vein injections
Intravenous injections
into the muscle
Intramuscular injections
into the abdominal cavity
Intra peritoneal injections
into the skin
Intradermal injections
under the skin
Subcutaneous injections
generally produce the greatest effect and the most rapid response when inserted directly into the bloodstream
toxic chemicals
exposure to a chemical for 24 hours or less
acute
exposure to a chemical for more than 3 months.
chronic
exposure to a chemical for 1 month or less
sub-acute
exposure to a chemical between 1 to 3 months
sub-chronic
seen at or near the body part or parts where exposure occurred
local effects
The ______ in the organ is
dependent on the absorption, distribution, biotransformation, and excretion of the substance
concentration
occurs when a substance is changed from one form to
another, which may also change the toxic properties of the substance
biotransformation
The ________ at which a toxic substance is removed from the body determines whether it will have a toxic effect.
rate (speed)
The main way a chemical is excreted from the human body is through the _____
urine
also important in removing certain chemicals from the body.
kidneys, lungs and liver
liminates the greatest number of toxins than any other
tissue/organ
kidney
eliminate substances that are in the gaseous phase, like carbon
dioxide
lungs
removes substances like lead or DDT (pesticide) by excreting them into
bile
liver
all substances are poisonous there is non that is not poisonous (true or false)
true
right dose dufferentiates a poison and a remedy (true or false)
true
most common path of toxic substance exposure
contact with skin
easy penetrates the stratum corneum and moves quickly through the other layers of the skin and is rapidly absorbed into the bloodstream
malathion
does not esasily penetrate the stratum corneum so the rate of absorption is much slower
DDT
can increase the rate or amount of material absorbed
increasing concentration of toxic substance or the exposure time
factors affecting the dermal absorption of toxic substance
condition of the skin, chemical makeup of the toxic substance, increasing concentration of toxic substance or exposutre time
