Chapter 2: Dose Responses

Question 1

What is a hazard

Answer 1

the intrinsic properties of a toxicant or toxicant mixture

(the actual danger something poses)

Question 2

What is Risk?

Answer 2

Risk refers to the probability of an adverse outcome based on exposure to hazardous toxicant(s).

Question 3

Are all hazardous toxicants likely to cause harm?

Answer 3

No, many hazardous toxicants are quite hazardous, but the risk of being harmed by them is fairly small.

Question 4

What is Risk assessment?

Answer 4

Characterization of the probability of potentially adverse health effects from human (or other animals!) exposures to hazardous agents.

Question 5

what is Risk management?

Answer 5

Process by which policy actions are chosen to control hazards.

Question 6

Epidemiology

Answer 6

studies the patterns, causes, and effects of health and
disease conditions in defined populations

Question 7

What is the trouble with correlations?

Answer 7

A “real” correlation is a statistical test that tells you whether two
variables are changing together. This is NOT a cause-and-effect relationship! Correlation does not indicate causation!

Question 8

What is structure activity modelling?

Answer 8

do chemicals look like a known toxicant? based on the similarities in the chemical structures between one known chemical structure and one known, sec an make an educated guess on how the unknown reacts with the body

Question 9

What is a bioassay?

Answer 9

Quantitative estimation of the intensity or concentration of a biologically active chemical, measured via some biological response under standardized conditions

Question 10

What are some common animals used in bioassays?

Answer 10

mammals - rats, mice, guinea pigs, monkeys
fish - goldfish, fathead minnows, zebrafish
invertebrates - cladocerans, amphiphods

Question 11

What are the goals of toxicity testing?

Answer 11

1. Determine the range of doses over which the toxic responses are produced.
2. Identify the nature of the responses to a toxicant.
3. Extrapolate these results for risk assessment analyses for human exposure.

Question 12

What are the uses of bioassays in environmental toxicology?

Answer 12

1. Determine of the most sensitive species or life stage for
   different organisms (ie- does it affect birds more or fish).
2. Compare effects of different toxicants on a single organism.
3. Compare effects of other environmental factors that modify the effects of the toxicant.
4. Determine the maximum level of a toxicant that may occur in
   the environment without causing biological change (max does to not have an effect)

Question 13

Who was Paracelsus and what were his principles?

Answer 13

Paracelsus was a Swiss physician, and his principles stated that one should make a distinction between the therapeutic and toxic properties of chemicals, which are not always distinguishable except by dose.

Question 14

What is the significance of dose-response relationships in toxicology?

Answer 14

Dose-response relationships help to quantify the relationships between the exposure concentration (dose) and a defined endpoint (response).

Question 15

How are dose-response relationships often represented?

Answer 15

Dose-response relationships are often represented graphically, as a dose-response curve.

Question 16

What is the purpose of dose-response assessments?

Answer 16

The purpose of dose-response assessments is to quantify the relationship between the dose of a substance and the adverse effects it can cause.

Question 17

What is the first step in toxicity testing?

Answer 17

The first step in toxicity testing is often to determine the dose-response relationship of a substance.

Question 18

What does Paracelsus mean when he says that the therapeutic and toxic properties of chemicals are not always distinguishable except by dose?

Answer 18

Paracelsus means that a substance can have both beneficial and harmful effects, depending on the dose at which it is taken.

Question 19

Why is it important to make a distinction between the therapeutic and toxic properties of a substance?

Answer 19

It is important to make a distinction between the therapeutic and toxic properties of a substance because a substance can have both beneficial and harmful effects, depending on the dose at which it is taken.

Question 20

What does LC50 mean?

Answer 20

lethal concentration that would affect 50% of the populations

Question 21

What does LD50 mean?

Answer 21

lethal dose that would affect 50% of the population

Question 22

Dose response curves will change based on what? and what is the order of effectiveness?

Answer 22

route of exposure. injection, inhalation, ingestion, dermal

Question 23

How does the speed of the response change?

Answer 23

the speed of response is related to how quickly a toxicant can get into the blood stream.