Dose-Response Relationships

Question 1

the characteristic of exposure and the spectrum of toxic effects come together as

Answer 1

dose-response relationship

Question 2

two types of dose response relationships

Answer 2

individual dose-response relationship

quantal dose-response relationship

Question 3

describes the response of and individual organism to varying doses of a chemical

Answer 3

individual dose relationship

Question 4

characterizes the distribution of individual responses to different does in a population of individual organisms

Answer 4

quantal dose relationship

Question 5

bell shaped curve

Answer 5

normal frequency distribution

Question 6

the reason for normal distribution

Answer 6

differences in susceptibility to chemicals among individuals

Question 7

animals responding to the left end of the curve are

Answer 7

hypersusceptible

Question 8

animals responding to the right end of the curve are

Answer 8

resistant

Question 9

the minimally ED of any chemical that evokes a stated all or none response is the ___which cannot be determined experimentally

Answer 9

threshold dose

Question 10

units of NED are converted by the addition of five to the value to avoid negative numbers

Answer 10

probit units

Question 11

50% of the population will show an effect from a chemical

Answer 11

ED50

Question 12

50% of the population will show a toxic dose from a chemical

Answer 12

TD50

Question 13

50% of the population will die from exposure to a chemical

Answer 13

LD50

Question 14

the “graded” dose relationship in an individual over the entire dose range is actually

Answer 14

U-shaped

Question 15

the region of the dose response relationship for essential nutrients is commonly referred to as

Answer 15

deficiency

Question 16

there is considerable evidence to suggest that some nonnuritional toxic substances may also impart beneficial or stimulatory effects at low doses but that at high doses they produce adverse effects

Answer 16

hormesis

Question 17

factors to consider when talking about the threshold concept

Answer 17

test population size
time periods
endpoints
ED01 vs NOAEC

Question 18

important assumptions for generating proper dose-response curves

Answer 18

effects are caused by dosed chemical
magnitude of response is actually related to dose
response can be quantified reliable

Question 19

three assumptions that cover “magnitude of response is actually related to the dose”

Answer 19

there is a target site with which the chemical interacts
response is related to concentration at target site
concentration at target site is related to dose

Question 20

the ratio of the dose required to produce a toxic effect to the dose needed to elicit the desired therapeutic response

Answer 20

therapeutic index

Question 21

the larger the ratio the ____the relative safety

Answer 21

greater

Question 22

use the ED99 for the desired effect and the TD1 for the undesired effect

Answer 22

Margin of Safety (MOS)

Question 23

a chemical produces injury to one kind of living matter without harming another form of life even though the two may exist in intimate contact

Answer 23

selective toxicity

Question 24

generally the first toxicity test performed on a new chemical is

Answer 24

acute toxicity

Question 25

5 objectives of acute toxicity

Answer 25

1. provide estimate for intrinsic toxicity of a substance
2. provide information on target organs
3. identify species differences and susceptible species
4. establish the reversibility of the toxic response
5. provide information that will assists the design and dose selection for longer term studies

Question 26

performed to obtain information on the toxicity of a chemical after repeated administration

Answer 26

subacute toxicity

Question 27

common duration for subchronic testing

Answer 27

90 days

Question 28

principle goals of subchronic testing

Answer 28

establish the NOAEC

further identify and characterize specific organ(s) affected by the test compound

Question 29

use to establish regulatory values for acceptable pollutant levels

Answer 29

reference dose

Question 30

uses all the experimental data to fit 1 or more dose-response curves

Answer 30

benchmark dose

Question 31

performed similarly to subchronic studies except that the period of exposure is longer than three months

Answer 31

chronic toxicity

Question 32

dose that suppresses body weight gain slightly

Answer 32

maximum tolerable dose