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► Med Misc 57 > Scientific Foundations: Toxicology > Flashcards

Scientific Foundations: Toxicology Flashcards

1
Q

Target organ

A

The organ that is selectively affected by a harmful agent

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2
Q

Five criteria that must all be present to make a chemical toxic

A
  1. Its properties make it capable of producing harm
  2. It is present in sufficient amount
  3. It is present for sufficient time
  4. It is delivered by an exposure route that allows it to be absorbed
  5. It reaches the target body organ
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3
Q

Toxic agents can be classified by…

A

Their form of action on biologic systems

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4
Q

Types of toxic agents

A
  1. Asphyxiants
  2. Corrosives
  3. Irritants
  4. Sensitizers
  5. Carcinogens
  6. Mutagens
  7. Teratogens
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5
Q

Asphyxiants

A

Deprive the body tissue of oxygen

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6
Q

Types of asyphixiants

A
  1. Simple

2. Chemical

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7
Q

Simple asphyxiants

A

Displace oxygen and cause suffocation

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8
Q

Examples of simple asphyxiants

A
  1. Carbon dioxide
  2. Nitrogen
  3. Argon
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9
Q

Chemical asphyxiants

A

Prevent oxygen use by the cell, even when enough oxygen might be present

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10
Q

Examples of chemical asphyxiants

A
  1. Carbon monoxide

2. Cyanide

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11
Q

Corrosives

A

Cause irreversible tissue death

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12
Q

Examples of corrosives

A
  1. Ozone

2. Acid

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13
Q

Irritants

A

Cause temporary, but sometimes severe inflammation of the eyes, skin or respiratory tract

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14
Q

Example of irritant

A

Ammonia

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15
Q

Sensitizer

A

Cause allergic reactions after repeated exposure

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16
Q

Examples of sensitizers

A
  1. Nickel

2. Toluene diisocyanate (TDI)

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17
Q

Carcinogens

A

Are capable of causing cancer

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18
Q

Examples of carcinogens

A
  1. Asbestos
  2. Coal tar
  3. Vinyl chloride monomer
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19
Q

Mutagens

A

Toxins that cause changes to the genetic material of cells that can be passed on to future generations

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20
Q

Examples of human mutagens

A
  1. Ethylene oxide

2. Ionizing radiation

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21
Q

Teratogens

A

Cause malformations in an unborn child

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22
Q

Examples it teratogens

A
  1. Organic mercury compounds
  2. Ionizing radiation
  3. Some pharmaceuticals
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23
Q

Formaldehyde is what type of toxic agent?

A
  1. Irritant to eyes
  2. Irritant to respiratory tract
  3. Irritant to skin
  4. Sensitizer
  5. Carcinogen
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24
Q

Dose

A

Amount of agent that reaches target organ and is usually impossible to determine accurately

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25
Q

Dose is estimated by…

A
  1. Measuring the amount administered
  2. Measuring the amount in the environment which the person was exposed
  3. Measuring biomarkers in body tissues
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26
Q

Vapors of gases are expressed as…

A

Parts per million (ppm)

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27
Q

Solids (ie dusts or fumes) are expressed…

A

According to their weight per volume of air

Usually milligrams per cubic meter (mg/m3)

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28
Q

Higher concentrations of substances are absorbed in ——— amounts

A

Greater

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29
Q

Longer or more frequent periods of exposure lead to ——– absorbed doses

A

Greater

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30
Q

Acute exposure

A

Occurs when exposure in short term and absorption is fairly rapid

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31
Q

Chronic exposure

A

Refers to longer duration or repeated periods of contact

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32
Q

—— toxic exposures tend to be at higher levels, and —— exposures occur at lower concentrations

A

Acute

Chronic

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33
Q

Examples of workplace guidelines

A

Threshold limit values

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34
Q

Examples of workplace standards

A

Permissible exposure limits

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35
Q

Guidelines and standards indicate…

A

Upper limits of exposure concentrations that are not felt to pose a danger to workers who are exposed over normal work hours

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36
Q

Published limits —– be viewed as definitely “safe” levels

A

Cannot

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37
Q

Why guidelines and standards may be controversial

A
  1. Lack of scientific data
  2. Lack if agreement over levels associated with health effects
  3. Reality that levels that protect most individuals may not affect susceptible groups
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38
Q

Three major routes of exposure

A
  1. Inhalation
  2. Cutaneous
  3. Ingestion
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39
Q

The most common route of exposure in the occupational environment

A

Inhalation

40
Q

Where does most inhalation absorption take place

A

Alveoli

41
Q

Why does most inhalation absorption take place in the alveoli

A

Blood flow is high and close to inhaled air

42
Q

Common substance absorbed via inhalation route

A
  1. Gas

2. Particulate

43
Q

Size range of particulate that can be absorbed via inhalation

A

1-10 microns in diameter

44
Q

Absorption is influenced by

A
  1. Rate of respirations

2. Depth of respirations

45
Q

Individuals performing ——– may absorb substances at a higher rate

A

Heavy physical labor

46
Q

Target organ of most inhaled toxins

A

Lungs

47
Q

Examples of substances that gain entry through the lungs but have their effects elsewhere in the body

A
  1. Solvents

2. Carbon monoxide

48
Q

Skin provides a —— to most substances

A

Barrier

49
Q

Skin’s effectiveness as a barrier varies according to…

A
  1. Condition
  2. Site
  3. Properties of the chemical agent
50
Q

Modes of cutaneous entry

A
  1. Cross the epidermal layer
  2. Enter through hair follicles
  3. Trauma of injection or impalement
51
Q

Substances that penetrate skin most freely

A

Gases

52
Q

Substances that penetrate skin less freely than gases

A

Liquids

53
Q

Substances that do not penetrate the skin

A
  1. Solids that are insoluble in water

2. Fats

54
Q

Longer contact promotes ——— of absorption

A

Higher levels

55
Q

Factors that can promote a substances further absorption

A

Damage to epidermal cells by chemicals or trauma, such as abrasions

56
Q

——–or ——- can trap substances and lead to longer exposure periods

A
  1. Clothing

2. Gloves

57
Q

Least common route of entry in the occupational setting

A

Ingestion

58
Q

Ingestion increases in importance in cases of other types of environmental exposure such as…

A
  1. Food
  2. Water
  3. Substances encountered through hand-mouth activity
59
Q

——–, if ingested can have a direct adverse effect on the gastrointestinal tract

A

Caustic or irritant chemicals

60
Q

Some ingested toxins act —— following absorption

A

Systemically

61
Q

Smoking or eating at work sites can lead to consumption of toxins by way of contaminated…

A
  1. Hands
  2. Food
  3. Smoking materials
62
Q

Dose-response relationship

A

Describes the relationship between the level of exposure (dose) and the resulting toxic effects (response) in a susceptible population of humans or experimental animals

63
Q

Higher doses are generally associated with….

A

Responses in a greater proportion of individuals

64
Q

Identification of a dose-response relationship lends support to a theory that….

A

A substance causes a given effect

65
Q

——– provide a basis for evaluating a chemical’s relative toxicity

A

Dose-response curves

66
Q

Terms that describe toxicity of a substance

A
  1. Lethal dose, 50% (LD50)

2. Lethal concentration, 50% (LC50)

67
Q

Lethal dose, 50%

A

Dose that produces death in 50% of a group of experimental animals

68
Q

Lethal concentration, 50%

A

Concentration that produces death in 50% of a group of experimental animals

69
Q

LD50 and LC50 indices are —— for more toxic agents

A

Smaller

70
Q

LD50 of acetone

A

5,340 mg/kg

71
Q

LD50 of hydrogen cyanide

A

0.5mg/kg

72
Q

Type of study that is useful in providing information about potential toxic effects or target organs of a substance in humans

A

Animal studies

73
Q

When are the effects of toxins with long latency periods apparent?

A

May not be apparent until years after the exposure

74
Q

Work related exposures commonly consist of chemical ——

A

Mixtures

75
Q

Why are work related exposures to chemical mixtures a concern?

A

Because interactive effects may occur with two or more concurrent exposures

76
Q

Types of interactive effects

A
  1. Synergistic effects
  2. Antagonism
  3. Potentiation
77
Q

Synergistic effects

A

Caused by exposure to more than one toxin that surpass the sum of the separate effects of those toxins

78
Q

Antagonism between toxins results in…

A

An overall effect that is less than the sum of their separate effects

79
Q

Potentiation

A

Means that a chemical has no adverse effect on its own, but its presence increases the effect of another substance or makes that substance capable of exerting an effect

80
Q

Potentiation is often seen with….

A

Carcinogens

81
Q

Once toxins are absorbed, their fate in the body….

A

Varies

82
Q

Excretion

A

Involves the elimination of a material from the body

83
Q

Some chemicals are excreted unchanged into…

A
  1. Expired air
  2. Urine
  3. Feces
  4. Bile
  5. Perspiration
84
Q

Other avenues of excretion include:

A
  1. Milk
  2. Spinal fluid
  3. Saliva
  4. Hair
85
Q

Most chemicals and their metabolic products are excreted through..

A

The kidney/urine pathway

86
Q

Transformation

A

A process that results in a substance being changed in some way

87
Q

Chemicals may be transformed into substances that can be excreted by a process called

A

Biotransformation

88
Q

Products of biotransformation may ——– or ——- than their parent chemical

A

Either less toxic or more toxic

89
Q

This rate can affect individual susceptibility to a toxin.

A

The rate at which a person metabolizes a subsance

90
Q

Many agents are not metabolized or excreted immediately, but instead are….

A

Deposited in body tissue and slowly released and excreted over time

91
Q

Half-life

A

The term that describes the time it takes for one half of the total absorbed amount to be eliminated from the body

92
Q

The length of half-life depends on:

A
  1. The agent

2. The tissue in which it is stored

93
Q

Half-life of lead in bone

A

20 years

94
Q

Half-life of lead in blood

A

25-30 days

95
Q

Toxicology

A

The study of the adverse effects of chemicals on biological systems

► Med Misc 57 (49 decks)

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