Chapter 12

Question 1

toxicant

Answer 1

a substance that acts as a poison to humans or wildlife

Question 2

toxicity

Answer 2

the degree to harm a chemical substance can inflict

Question 3

toxicology

Answer 3

the scientific field that examines the effects of poisonous chemicals and other agents on humans and other organisms

Question 4

toxin

Answer 4

a toxic chemical stored or manufactured in the tissues of living organisms. for example, a chemical that plants use to ward off hervibors or that insects use to deter predators

Question 5

environmental toxicology

Answer 5

the study of toxicants that come from or are distributed into the environment, including the study of health effects on humans, animals, and other ecosystems

Question 6

mutagen

Answer 6

a toxicant that causes mutations in the DNA of organisms

Question 7

teratogen

Answer 7

a toxicant that causes harm to the unborn, resulting in birth defects

Question 8

carcinogen

Answer 8

a chemical or type of radiation that causes cancer

Question 9

allergen

Answer 9

a toxicant that over activates the immune system, causing an immune response when one is not necassary

Question 10

endocrine disrupters

Answer 10

a toxicant that interferes with the endocrine (hormone) system

Question 11

pathway inhibitor

Answer 11

a toxicant that interrupts vital biochemical processes in organisms by blocking one or more steps in important biochemical pathways. compounds in the herbicide atrazine kill plants by blocking key components in the process of photosynthesis

Question 12

neurotoxin

Answer 12

a toxicant that assaults the nervous system. neurotoxins include heavy metals, pesticides, and some chemical weapons developed for use in war

Question 13

acute exposure

Answer 13

exposure to a toxicant occurring in high amounts for short periods of time

Question 14

chronic exposure

Answer 14

exposure for ling periods of time to a toxicant occurring in low amounts

Question 15

bioaccumilation

Answer 15

the buildup of toxicants in the tissues of an animal

Question 16

biomagnification

Answer 16

the magnification of the concentration of toxicants on an organism caused by its consumption of other organisms in which toxicants have bioaccumulated

Question 17

case history

Answer 17

medical approach involving the observation and analysis of individual patients

Question 18

epidemiological study

Answer 18

a study that involves large-scale comparisons among groups of people, usually contrasting a group known to have been expected to some toxicant and a group that has not

Question 19

dose response analysis

Answer 19

a set of experiments that measure the response of test animals to different doses of toxicants. the response is generally quantified by measuring the proportion of animals exhbiting negative effects

Question 20

dose

Answer 20

the amount of toxicant a test animal recieves in a dose response test

Question 21

response

Answer 21

the type or magnitude of negative effects on animal exhibits in response to a dose of toxicant in a dose-response analysis

Question 22

threshold dose

Answer 22

the amount of a toxicant at which it begins to affect a population of test animals

Question 23

LD50 (lethal dose-50%)

Answer 23

the amount of a toxicant it takes to kill 50% of a population of test animals

Question 24

ED50 (effective dose-50%)

Answer 24

the amount of a toxicant it takes to affect 50% of a population of test animals

Question 25

dose response curve

Answer 25

a curve that plots the response of test animals to different doses of a toxicant, as a result of dose-response analysis

Question 26

synergistic effects

Answer 26

a interactive effect (as of toxicants) that is more than or different from the simple sum of their constituent effects

Question 27

risk assessment

Answer 27

the quantitative measurement of risk, together with the comparison of risks involved in different activities or substances

Question 28

risk management

Answer 28

the process of considering information from scientific risk assessment i light of economic, social, and political needs and values, in order to make decisions and design strategies to minimize risk

Question 29

risk

Answer 29

the mathematical probability that some harmful outcome (death, environmental or economic loss) will come from a given action, event, or substance

Question 30

REACH (registration, evaluation, authorization,and restriction of chemicals)

Answer 30

program of the EU that shifts the burden of proof for testing chemical safety from national governments to industry and requires that a chemical substance produced over 1 metric ton per year be registered with the new European chemical agency REACH

Question 31

toxic substances control act

Answer 31

a 1976 US law that directs the environmental protection agency to monitor thousands of industrial chemicals and gives the EPA authority to regulate and ban substances that pose excessive risk