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EHS 3310 > Environmental Toxicology (16) > Flashcards

Environmental Toxicology (16) Flashcards

1
Q

**Toxicology:

A

the science of poisons; the study of the adverse effects of chemical, physical, or biological agents on living organisms

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2
Q

Toxicologist:

A

scientist who has received extensive training in order to investigate in living organisms the adverse effects of xenobiotics and assess the probability of their occurrence

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3
Q

Xenobiotic:

A

a foreign substance taken into the body; can be beneficial or toxic (pharmaceuticals vs. lead)

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4
Q

Three factors that determine a substance’s risk on the ATSDR Priority List:

A

frequency, toxicity, potential for human exposure

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5
Q

9 Fields of toxicology:

A

mechanistic, descriptive, regulatory, forensic, clinical, environmental, ecotoxicological, reproductive, developmental

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6
Q

mechanistic toxicology:

A

identifies the cellular, biochemical, and molecular mechanisms by which chemicals exert toxic effects on living organisms; detailed descriptions of how a chemical works; from the time it might be absorbed to the time when the adverse health effects take effect

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7
Q

descriptive toxicology:

A

concerned directly with toxicology testing; find the test that will suffice to give us the necessary information; provides information for safety evaluation and regulatory requirements

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8
Q

regulatory toxicology:

A

determines whether a chemical poses a sufficiently low risk to be marketed for a stated purpose and establishes standards for the amounts of chemicals permitted in ambient air, industrial atmospheres, and drinking/recreational waters; EPA, NIOSH, etc.

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9
Q

forensic toxicology:

A

focuses primarily on the medicolegal aspects the harmful effects of chemicals on humans and animals; think Law and Order

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10
Q

clinical toxicology:

A

concerned with diseases caused by or uniquely associated with toxic substances; encompasses expertise in the specialties of medical toxicology, applied toxicology, and clinical poison information

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11
Q

environmental toxicology:

A

focuses on the impacts of chemical pollutants in the environment on biological organisms, specifically studying the impacts of chemicals on nonhuman organisms such as fish, birds, and terrestrial animals

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12
Q

ecotoxicology:

A

study of the release of toxic pollutants into the environment, especially into aquatic systems, by focusing on how these toxicants ay become distributed within food chains and by measuring the toxic responses made within a particular ecosystem to such pollutants

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13
Q

reproductive toxicology:

A

examines the association between chemicals or physical agents and adverse effects upon the reproductive system [we can have this for various organ systems, e.g. a cardiovascular toxicologist]

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14
Q

developmental toxicology:

A

studies the effects of natural and man-made chemicals (some classified as teratogens) on prenatal development or postnatally until the time of puberty

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15
Q

teratogen:

A

substance which causes birth defects

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16
Q

Paracelsus

A

father of toxicology; said that specific chemicals are responsible for the toxicity of plant or animal poisons; documented that bodily response depended on dose received of a substance; contributed the notion of target organ specificity of chemicals

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17
Q

Who said it? “All substances are poisons; there is none which is not a poison. The right dose differentiates a poison and a remedy.”

A

Paracelsus

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18
Q

Orfila

A

founder of toxicology; described in detail types of poisons and their bodily effects; demonstrated the effects of poisons on specific organs through analysis during autopsies

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19
Q

toxicity:

A

the degree to which something is capable of producing deleterious effects, which is related to its physical and chemical properties; can be acute or chronic

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20
Q

poison:

A

any agent capable of producing an immediate deleterious response in a biological system when experienced in small amounts

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21
Q

toxic agent:

A

very generally, a material or factor that can be harmful to biological systems

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22
Q

**toxin:

A

a toxic substance made by living organisms (reptiles, insects, plants, microorganisms)

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23
Q

**toxicant:

A

toxic substances that are man-made or result from anthropogenic (human) activity

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24
Q

systematic toxin:

A

affects the entire body or many organs rather than a specific site

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25
Q

organ toxin:

A

affects only a specific tissue or organ(s) without producing damage to the body as a whole

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26
Q

dose (and the three parts to consider):

A

the amount of substance administered at one time (consider number of doses, frequency, and total time of treatment)

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27
Q

common units for dose measurement

A

mg/kg, also mg/L, mg/g, mg/m3, ppm, ppb, ppt

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28
Q

exposure dose:

A

amount of a xenobiotic encountered in the environment

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29
Q

absorbed dose:

A

actual amount of exposed dose that enters the body

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30
Q

administered dose:

A

quantity administered usually orally or by injection

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31
Q

total dose:

A

sum of all individual doses

32
Q

fractionating (and why used):

A

breaking up a dose (decreases the probability that the total dose will cause toxicity)

33
Q

external dose:

A

dose acquired by contact with contaminated environmental sources

34
Q

internal dose:

A

portion of a substance that becomes internalized in the body through ingestion, absorption, injection, or other means

35
Q

biologically effective dose:

A

the portion of the internal dose that is required to cause a health outcome

36
Q

LD50:

A

Lethal-Dose 50- the dosage causing death in 50% of exposed animals

37
Q

**dose-response:

GUARANTEED IMPORTANT– go back to slides as well

A

a type of correlative relationship between the characteristics of the exposure and spectrum of resulting effects; based on observed data from experimental animal, human clinical, and cell studies

38
Q

ED

A

effective dose

39
Q

TD

A

toxic dose

40
Q

Therapeutic index (TI)

A

compares the therapeutically effective dose (ED) to the toxic dose (LD); generally LD50/ED50

41
Q

Margin of Safety (MOS):

A

often used to denote the safety of a drug; LD01/ED99; bigger is better

42
Q

Adverse effect levels (2):

A

NOAEL: no observed adverse effect level
LOAEL: lowest observed adverse effect level

43
Q

**Four steps of exposure to xenobiotics:

A
  1. absorption
  2. distribution
  3. metabolism
  4. excretion
    (ADME)
44
Q

absorption:

A

from the site of exposure to the body

45
Q

distribution:

A

from bloodstream to the targeted tissues and organs (central compartment = blood and plasma) (the target organ of toxicity is often not the site of the highest concentration)

46
Q

first-pass effect:

A

chemicals absorbed in the intestine go to the liver first, before entering systematic circulation

47
Q

metabolism:

A

chemicals undergo biotransformation (conversion)

48
Q

excretion:

A

agent (may no longer be toxic) from the tissues/organs out of the body

49
Q

direct effect (response to xenobiotic):

A

an immediate impact upon the cells and tissues of the body or upon specific target organs

50
Q

indirect effect (response to xenobiotic):

A

a change in the function of the body’s biochemical processes

51
Q

toxicokinetics

A

the quantitation of the time course of toxicants in the body during the processes of absorption, distribution, biotransformation, and
excretion or clearance of toxicants; a reflection of how the body handles
toxicants as indicated by the plasma concentration of that xenobiotic at various time points

52
Q

toxicodynamics

A

the molecular, biochemical, and physiological effects of toxicants or their metabolites in biological systems; the result of the interaction of the
biologically effective dose of the ultimate (active) form of the toxicant with a molecular target

53
Q

local effect:

A

damage at the site where a chemical comes into contact with the body

54
Q

systemic effect:

A

adverse effect associated with generalized distribution of the chemical throughout the body by the bloodstream to internal organs

55
Q

target organ effect

A

some chemicals may confine their effects to specific organs such as the liver, lungs, heart, kidneys, or nervous system

56
Q

**Factors that affect responses to a target agent

A
  1. form and innate chemical activity (e.g. Cr-3 and Cr-6)
  2. mode, route, and site of entry
  3. length and duration of exposure
  4. individual responses to toxic exposures (age, sex, species, health status, genetic background, medications, tobacco and alcohol use, pregnancy, allergy)
    * *5. effects of chemical mixtures (could be additive, synergistic, antagonistic, potentiation)
  5. latency and delayed responses
  6. methods of testing
57
Q

**Additive:

GUARANTEED

A

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

(e. g. tranquilizer and alcohol)
* *most common**

58
Q

**Synergism:

GUARANTEED

A

the combined effect of exposures to two or more chemicals is greater than the sum of their individual effects
(e.g. cigarette smoke + radon)

59
Q

**Antagonistic:

GUARANTEED

A

two chemicals administered together interfere with each other’s actions or one interferes with the action of the other, thus their combined effect is less than the sum of their individual effects
basis for most antidotes

60
Q

**Potentiation:

GUARANTEED

A

one chemical that is not toxic causes another chemical to become more toxic
(e.g. CCl3’s effects enhanced greatly by rubbing alcohol)

61
Q

Latency:

A

the time period between initial exposure and a measurable response (seconds to decades)

62
Q

Possible subject types (3):

A
  1. volunteers who have had normal or accidental exposures
  2. animals exposed purposely (in vivo)
  3. cells derived from human, animal, or plant sources (in vitro)
63
Q

**Methods of testing for toxicity (3):

Most common?

A
  1. animal studies
  2. epidemiologic studies (most common)
  3. clinical trials
64
Q

**Acute toxicity:

A

occurs almost immediately, usually a single dose or series of doses received within 24 hours

65
Q

**Subacute toxicity:

A

resulting from exposures of less than 1 month

66
Q

**Subchronic toxicity:

A

results from repeated exposure for months

67
Q

**Chronic toxicity:

A

cumulative damage that takes several months to years to become recognized

68
Q

**Carcinogenicity:

A

a complex, multistage process of abnormal cell growth and differentiation that can lead to cancer

69
Q

Three steps of carcinogenicity:

A
  1. initiation (normal cell undergoes irreversible changes)
  2. promotion (initiated cells are stimulated to progress to cancer)
  3. progression
70
Q

**Developmental toxicity:

A

pertains to adverse toxic effects to the prenatal development or postnatally until the time of puberty

71
Q

Embryolethality:

A

failure to conceive, spontaneous abortion, or stillbirth

72
Q

Embryotoxicity:

A

growth retardation or delayed growth of specific organ systems

73
Q

Teratogenicity:

A

irreversible conditions that leave permanent birth defects in live offspring

74
Q

**Genetic toxicity:

A

results from damage to DNA and altered gene expression (mutagenesis)

75
Q

Mutation vs mutagen

A

mutation: genetic change
mutagen: agent causing the genetic change

EHS 3310 (10 decks)

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