Chapter 5 - Toxicology Flashcards
Toxicology
study of the adverse effects of chemicals on living organisms
toxicity
degree to which a substance can harm an exposed organism
hazard
the potential for a substance to cause harm (toxicity plus exposure)
risk
quantitative measurement or estimate of a hazard
poisen
substance that is harmful to an organism
xenobiotic
substance found in an organism but which is not normally produced or expected to be present in it
dose response theory
increasing dose, increasing response
tolerance
increased ability to withstand exposure
chronic exposure
long term exposure
acute exposure
short term - minutes, hours, days
NOEL
no observed effect level
NOAEL
no observed adverse effect leel
LOEL
lowest observed effect level
LOAEL
lowest observed adverse effect level
latency period
period of time between exposure and onset of symptoms
LD50
lethal dose, amount of material (normally liquids or solid) that kills 50% of laboratory animals
LC50
lethal concentration . amount of material (normally air-borne concentrations) that kill 50% of laboratory animals
IDLH
immediately dangerous to life and health
Routes of entry
Inhalation, Ingestion, Absorption, Percutaneous and Intravenous Injections
Chemical combinations - additive
combined effect of chemicals equal to sum of each chemical acting independently
Chemical combinations - antagonistic
when combined the two chemical interfere with each other
Chemical combinations - synergistic
combined effect of two chemicals is much greater than the sum of the effect of each agent acting independently
chemical combinations- potentiating
one substance does not have a toxic effect on a certain organ system, however, when combined with another chemical, the combination can have a toxic effect
carcinogen
substance or agent known to cause cancer, carcinogens to do not adhere to dose response curve
caocarcinogen
these agents, when applied immediately before or with a genotoxic carcinogen, enhance the oncogenic (cancerous) effect of the agent
epigenetic
changes in phenotype or gene expression caused by mechanisms other than changes in the underlying DNA sequence
genotoxic
materials known to be potentially mutagenic and carcinogenic in nature. They act by directly altering the DNA
mutagen
physical or chemical agent that changes the genetic material (usually DNA) of an organism and thus increases the frequency of mutagens above the natural background level
teratogens
an agent that can disturb the development of an embryo or fetus
Four stages of cancer
initiation, latency period, promotion, progression
Cancer initiators
Can be reactive with DNA
Can require drug metabolizing enzymes in the body which make them available to cause changes in DNA
often specific to particular tissue , types or species
effects are irreversible
Cancer promotion
When mutation occurs as result of initiator, promoter compounds promote the proliferation of the cell, giving rise to a large number of daughter cells containing mutation
progression
transformation of a benign tumor to a neoplasma and to malignancy
Types of poisens
hepatoxin (liver or blood), nephrotoxin (kidneys), neurotoxin (nervous system)