PUBH 6011 FINAL EXAM QUESTIONS AND ANSWERS
VERIFIED 100% CORRECT
Exposure pattern influencing dose response - ANSWER- acute toxicity:
happens quickly
- usually after 1 dose
- include death, CNS effects, irritation, etc.
Chronic:
- result of prolonged exposure, usually lower doses than acute
- organ damage, cancer
- eventually it will build up to a point where the adverse effect occurs
frequently little relationship between the two
Pharmacokinetics influencing dose response - ANSWER- can differ by
species, sex, age, nutrition, disease, enzyme induction (prior exposure)
- how the body responds to a specific dose/exposure
DDT LD50 in rats - ANSWER- - newborn rats have a higher tolerance
for DDT
- the lower the LD50, the more toxic the chemical is (bc it takes less of
it to have effects)
- age influences toxicity/response in either direction
Species and strain in dose response - ANSWER- - can differ between
strains due to different mechanisms of action/different receptors
between species
- common to assume that humans are the most sensitive when studying
and use the most sensitive species to begin studying the chemical
,LD50 - ANSWER- - dose (mg/kg) lethal to 50% of test animals
- determined orally, through inhalation or by dermal exposure
LC50 - ANSWER- - concentration (in ppm or mass/volume) lethal to
50% of test animals
- something in the water, air, etc. where you can measure the
concentration in the environment
Subchronic/chronic tox testing - ANSWER- - concerned with long term
exposure to lower doses
- test for damage to certain organs
- damage to functional systems (neuro, immuno, etc.)
- test for carcinogenicity
Mechanic studies - ANSWER- - study of potential models of action in
lab animals (in vivo) or with isolated tissues, cells or components (in
vitro)
strengths:
- compound specific info
- understanding biology should improve
problems:
- difficult to rule out alternative theories
- lack necessary data for humans
Assessing risks - ANSWER- - personal: risk of walking, driving, etc.
- public health
- occupational health: setting workplace standards
- architects: risk of structure injuring people, earthquakes
- medical: risk of side effects from new drugs
- dept of transportation: traffic, hazardous material transport
,actuarial risks - ANSWER- - based on experience with the same risk
- predictions made with great deal of precision
- diseases, auto accidents, etc.
modeled risks - ANSWER- - based on data and theory
- predictions subject to uncertainty
- cancer risk from chemicals, climate change, etc.
- don't have data exactly on what we are interested in/may not predict
exactly
Risk assessment paradigm - ANSWER- - hazard identification: which
adverse effects?
- dose-response: how much does it take?
- exposure assessment: how much do people take in?; usually the level
that you would manage at bc you can't change the toxicity of the thing
itself
- risk characterization: estimate magnitude of risk and uncertainty
Hazard identification - ANSWER- - physical/chemical properties
- epidemiology
- toxicology
- asks what harmful effects is the agent capable of causing?
Types of adverse effects - ANSWER- - acute toxicity
- irritation
- corrosivity
- sensitization
- repeated dose toxicity
- mutagenicity
- carcinogenicity
- toxicity for reproduction
, IARC Carcinogen Classification - ANSWER- - organization of WHO,
mission to review the evidence for carcinogenicity of chemicals
- human evidence is almost always epi data
- always none, inadequate, sufficient, limited evidence
Exposure assessment - ANSWER- - how much of the substance of
concern are people exposed to?
- what are the sources of exposure?
Exposure and dose - ANSWER- exposure: air breathed, water ingested,
dermal contact; usually measured as concentration
dose: quantity taken into the body
- administered dose: amount taken into the body (ie pill)
- absorbed dose: crosses a biological barrier into the body
Measuring and modeling exposure - ANSWER- measured:
- more precise
- more expensive
- source must be present
modeled:
- rely on models using chemical and climate information
- require many assumptions
- models imprecise and rarely validated
- allow better incorporation of time into exposure estimates
exposure pathways - ANSWER- - inhalation, absorption, ingestion
- air, soil, water, diet
VERIFIED 100% CORRECT
Exposure pattern influencing dose response - ANSWER- acute toxicity:
happens quickly
- usually after 1 dose
- include death, CNS effects, irritation, etc.
Chronic:
- result of prolonged exposure, usually lower doses than acute
- organ damage, cancer
- eventually it will build up to a point where the adverse effect occurs
frequently little relationship between the two
Pharmacokinetics influencing dose response - ANSWER- can differ by
species, sex, age, nutrition, disease, enzyme induction (prior exposure)
- how the body responds to a specific dose/exposure
DDT LD50 in rats - ANSWER- - newborn rats have a higher tolerance
for DDT
- the lower the LD50, the more toxic the chemical is (bc it takes less of
it to have effects)
- age influences toxicity/response in either direction
Species and strain in dose response - ANSWER- - can differ between
strains due to different mechanisms of action/different receptors
between species
- common to assume that humans are the most sensitive when studying
and use the most sensitive species to begin studying the chemical
,LD50 - ANSWER- - dose (mg/kg) lethal to 50% of test animals
- determined orally, through inhalation or by dermal exposure
LC50 - ANSWER- - concentration (in ppm or mass/volume) lethal to
50% of test animals
- something in the water, air, etc. where you can measure the
concentration in the environment
Subchronic/chronic tox testing - ANSWER- - concerned with long term
exposure to lower doses
- test for damage to certain organs
- damage to functional systems (neuro, immuno, etc.)
- test for carcinogenicity
Mechanic studies - ANSWER- - study of potential models of action in
lab animals (in vivo) or with isolated tissues, cells or components (in
vitro)
strengths:
- compound specific info
- understanding biology should improve
problems:
- difficult to rule out alternative theories
- lack necessary data for humans
Assessing risks - ANSWER- - personal: risk of walking, driving, etc.
- public health
- occupational health: setting workplace standards
- architects: risk of structure injuring people, earthquakes
- medical: risk of side effects from new drugs
- dept of transportation: traffic, hazardous material transport
,actuarial risks - ANSWER- - based on experience with the same risk
- predictions made with great deal of precision
- diseases, auto accidents, etc.
modeled risks - ANSWER- - based on data and theory
- predictions subject to uncertainty
- cancer risk from chemicals, climate change, etc.
- don't have data exactly on what we are interested in/may not predict
exactly
Risk assessment paradigm - ANSWER- - hazard identification: which
adverse effects?
- dose-response: how much does it take?
- exposure assessment: how much do people take in?; usually the level
that you would manage at bc you can't change the toxicity of the thing
itself
- risk characterization: estimate magnitude of risk and uncertainty
Hazard identification - ANSWER- - physical/chemical properties
- epidemiology
- toxicology
- asks what harmful effects is the agent capable of causing?
Types of adverse effects - ANSWER- - acute toxicity
- irritation
- corrosivity
- sensitization
- repeated dose toxicity
- mutagenicity
- carcinogenicity
- toxicity for reproduction
, IARC Carcinogen Classification - ANSWER- - organization of WHO,
mission to review the evidence for carcinogenicity of chemicals
- human evidence is almost always epi data
- always none, inadequate, sufficient, limited evidence
Exposure assessment - ANSWER- - how much of the substance of
concern are people exposed to?
- what are the sources of exposure?
Exposure and dose - ANSWER- exposure: air breathed, water ingested,
dermal contact; usually measured as concentration
dose: quantity taken into the body
- administered dose: amount taken into the body (ie pill)
- absorbed dose: crosses a biological barrier into the body
Measuring and modeling exposure - ANSWER- measured:
- more precise
- more expensive
- source must be present
modeled:
- rely on models using chemical and climate information
- require many assumptions
- models imprecise and rarely validated
- allow better incorporation of time into exposure estimates
exposure pathways - ANSWER- - inhalation, absorption, ingestion
- air, soil, water, diet
