2 - toxicology

Question 1

what is toxicology

Answer 1

the study of adverse SYSTEMIC effects of chemicals on living organisms

Question 2

what is a toxicant

Answer 2

a chemical that does SYSTEMIC damage

Question 3

what is a poison

Answer 3

reserved now for special class of toxicants that need only a small dose to cause death

Question 4

founder of modern toxicology

Answer 4

paracelsus

Question 5

paracelsus’ main contribution

Answer 5

dose response relationship - the observation that the effects of a poison are related to the strength of its dose

he also was the first to publish a description of the symptoms of chronic mercury poisoning, and developed a chemotherapy treatment using mercury to treat syphillis

Question 6

why is arsenic called a heavy metal

Answer 6

has a high molecular weight

Question 7

is arsenic poisonous by itself

Answer 7

no, arsenious oxide or arsenic trioxide are poisonous

however, there are two non-poisonous variants called arsenobetaine and arsenocholine which is found in shellfish, cod, and haddock

Question 8

what was ramazzini’s contribution

Answer 8

he was concerned with the diseases of workers, listed the illnesses and diseases occurring in many occupations

he was an epidemiologist who studied occupational medicine

Question 9

poison is dependent on

Answer 9

the “sufficient quantity” - all things are poisons, the dose defines the poison

Question 10

rammazzini used ___ to treat malaria

Answer 10

the bark of a cinchona tree

Question 11

ecotoxicology

Answer 11

concerned with the release of toxic pollutants into the environment, especially aquatic systems, by examining how they become distributed within the food chains

Question 12

spectrum of toxic dose

Answer 12

describes the toxicity or hazards that are related to exposure to a particular chemical

Question 13

dose response curve components

Answer 13

x axis = dose in mg per kg

y axis = response %

NOAEL = no-observed adverse effect level

LOAEL = lowest observed adverse effect level

ED50 = dose which causes an effect in 50% of population - median effective dose

LD50 = causes death in 50% of population - median lethal dose

Question 14

toxic agent

Answer 14

a material/factor that can be harmful to biological (human) systems

Question 15

toxicity

Answer 15

the degree to which something is poisonous, related to a material’s physical and chemical properties

low-toxicity means you can ingest large quantities with little effect

high-toxicity means you even small quantities can cause large effects

Question 16

toxicant

Answer 16

toxic substances which are man-made or result from human activity

Question 17

toxin

Answer 17

usually refers to a toxic substance made by living organisms

Question 18

hazard

Answer 18

the inherent capability of an agent or a situation to have an adverse effect. a factor or exposure that may adversely affect health.

Question 19

what information is required to identify and categorize a chemical hazard

Answer 19

physical and chemical properties - organic and inorganic

setting and nature - where would you encounter the hazard

CEPA 1999 - Canadian environmental protection act

Question 20

threshold toxicant

Answer 20

assumes there is harm at a particular level of exposure

those for which the critical effect is not considered to be cancer or heritable mutations

Question 21

non-threshold

Answer 21

substances for which the critical effect is carcinogenesis - assumes that there is some probability of harm to human health at any level of exposure

Question 22

describe a population dose-response curve

Answer 22

• S shaped/sigmoidal curve which demonstrates the relationship of observed responses in a population to varying levels of some substance

Question 23

what does the flat portion at the beginning of a dose-response curve represent

Answer 23

suggests that at low levels of some substances, an increase in dose produces no effect

this is referred to as the subthreshold phase

Question 24

relationship between potency and LD50

Answer 24

a smaller LD50 indicates a more potent substance

Question 25

define threshold in a dose-response curve

Answer 25

the threshold is the lowest dose at which a particular response may occur

Question 26

maximum response/plateau/ceiling effect

Answer 26

point at which increases in dose no longer produce an increase in response

Question 27

relationship between height of maximum response and efficacy

Answer 27

slopes whose plateau is higher up on the y axis (higher maximum response) are more efficient

Question 28

what does slope indicate on a dose-response curve

Answer 28

how sharply the response changes with an increase in dose steep slope suggests significant changes in response even with small dose variations steeper curves are more toxic

Question 29

potency and dose response curve

Answer 29

look at the location of the whole curve along the x axis (dose axis)

Question 30

acute

Answer 30

single exposure for less than 24 hours

Question 31

subacute

Answer 31

exposure for one month or less

Question 32

subchronic

Answer 32

exposure for 1-3 months

Question 33

chronic exposure

Answer 33

3+ months

Question 34

additive chemical mixtures

Answer 34

combination of two chemicals produce an effect that is equal to their individual effects added together

Question 35

synergism

Answer 35

the combined effect of exposures to two or more chemicals is greater than the sum of their individual effects

Question 36

potentiation

Answer 36

one chemical that is not toxic causes another chemical to become more toxic

Question 37

coalitive interaction

Answer 37

when several agents that have no known toxic effects interact to produce a toxic effect

Question 38

antagonism

Answer 38

two chemicals administered together interfere with each other's actions, or one interferes with the action of the other

Question 39

chemical allergy

Answer 39

an immunologically mediated adverse reaction to a chemical resulting from previous sensitization a chemical or a structurally similar one

Question 40

latency

Answer 40

time period between initial exposure and a measurable response

Question 41

risk assessment

Answer 41

a process for identifying adverse consequences and their associated probability

Question 42

list some factors that affect responses to a chemical

Answer 42

concentration route/site of exposure duration/frequency of exposure dose drug interactions individual sensitivity

Question 43

exposure route with the fastest speed of effect

Answer 43

blood stream

Question 44

T/F - many carcinogens are believed to have a latency period of 10-40 years

Answer 44

true

Question 44

three aspects of risk with regard to toxicology

Answer 44

risk assessment - science-based - hazard identification, dose-response assessment, exposure assessment, risk characterization risk management - policy based risk communication

Question 45

risk managment

Answer 45

consists of actions taken to control exposures to toxic substances in the environment

Question 46

T/F - exposure assessment is the weakest aspect of risk assessment

Answer 46

true - methods are unable to provide adequate quantitative information about human exposures

Question 47

what two factors are considered when assessing level of contact for those who live near a discharge location

Answer 47

location of nearby populations daily human activities that influence how often people come in contact with the chemical

Question 48

what three factors are used to determine level of contact for consumer product or worker exposures

Answer 48

frequency of use duration use conditions

Question 49

risk characterization integrates what three things

Answer 49

hazard identification dose-response assessment exposure assesment

Question 50

what kind of summary would you present to a policymaker to decide if a risk is sufficient and needs to be addressed

Answer 50

risk characterization summary

Question 51

descriptive tox

Answer 51

gathering information on a chemical and how it would cause illness or death through animal studies

Question 52

mechanistic tox

Answer 52

delineating how toxic substances cause their effects

Question 53

regulatory tox

Answer 53

gathering and evaluating evidence to create evidence based standards for safe exposure limits