GASES AND VAPORS

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GASES AND VAPORS

• A chemical substance where all the molecules are
  not connected within any sort of structure and so
  are free to move completely at random, colliding
  with one another and exchanging energy between
  one another (i.e., in thermal motion).

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WHAT MAKES CHEMICALS IN THE ENVIRONMENT HARMFUL?

• Reactions with living cells that may modify
  normal functions or otherwise cause changes,
  resulting in damage and structural (including
  DNA) defects
• Cancer a particular concern but only one among
  many

3
RADIATION

• Definition energy that may be propagated through
  air or some other medium, or through a vacuum
• electromagnetic
• fundamental particles
• Ionizing versus non-ionizing

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ELECTROMAGNETIC ENERGY

• Radiation in the form of quanta emitted during
  energy transitions in atoms or molecules-
• at the atomic level
• at the nuclear level
• ? visible light, UV, X-rays, gamma rays.

5
PARTICLE ENERGY

• Nuclear particles released during radioactive
  decay of unstable atoms (radionuclides)-
• alpha-particles (2 protons, 2 neutrons He)
• beta-particles (1 electron)
• neutrons (no charge)

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WHAT MAKES RADIATION HARMFUL?

• Energy transmitted during collisions with cells
  may cause changes, resulting in damage and
  structural (including DNA) defects.
• Cancers a particular concern.

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BIOLOGICAL AGENTS

• Microorganisms
• viruses, bacteria, fungi, etc. ? infection,
  allergic reactions, etc.
• Toxins of biological origin
• bites or stings ? inflammation, intoxication,
  allergic reactions, etc.
• Allergens from plants
• certain plants ? dermatitis, rhinitis, asthma
• Protein allergens from animals
• certain animals ? allergic reaction

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BIOLOGICAL AGENTS

• Toxins
• Exotoxins
• Toxins secreted by the organism
• Endotoxins
• toxins produced by a microorganism that are
  retained within the cell, and is released - in
  the form of very fine particulate matter - when
  the cell dies and disintegrates

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Endotoxin

• A Gram-negative bacterium.   Electron micrograph
  of Escherichia coli (a), together with a
  schematic representation of the location of
  lipopolysaccharide (LPS endotoxin) in the
  bacterial cell wall (b) and the architecture of
  LPS (c). provided by M. Rhode, German Research
  Centre for Biotechnology, Braunschweig, Germany.

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WHAT MAKES BIOLOGICAL AGENTS HARMFUL?

• Allergic Reactions
• Repeated exposures resulting in recognition and
  sensitization of the immune system to foreign
  substances (most often proteins) derived from
  microorganisms, plants, or animals
• Inflammatory response on re-exposure typically
  results in asthma if inhaled or dermatitis if
  skin contact

Dust Mite
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WHAT MAKES BIOLOGICAL AGENTS HARMFUL?

• Infection
• Invasion of microrganisms in which conditions are
  favorable for growth, production of toxins and
  damage to tissue

Giardia
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PHYSICAL AGENTS

• Thermal stress (hot, cold)
• Vibration (direct transmission of mechanical
  energy)
• Noise (radiation of mechanical energy)

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WHAT MAKES PHYSICAL AGENTS HARMFUL?

• Mechanical or thermal energy transmitted to
  cellular or larger-scale systems, resulting in
  damage

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CLASSIFICATION OF ENVIRONMENTS

• AIR vs WATER vs FOOD
• AMBIENT/ENVIRONMENTAL vs OCCUPATIONAL
• INDOOR vs OUTDOOR

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DISPERSAL OF CHEMICAL AND BIOLOGICAL AGENTS

• Sources
• defined in terms of what is emitted and where,
  and its strength
• Sinks
• locations within which the agent may reside and
  accumulate after emission
• Receptors (or targets)
• the exposed population

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The Continuum From Emission of a Contaminant
(adverse agent) to a Health Effect
Potential dose to body
Transport and transformation
Contaminant source emissions
Accumulation in environment
Human contact exposure
Early expression of disease
Internal dose
Health Effect
Biologically effective dose
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Environmental exposure pathways I
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The Continuum From Emission of a Contaminant
(adverse agent) to a Health Effect
Potential dose to body
Transport and transformation
Contaminant source emissions
Accumulation in environment
Human contact exposure
Early expression of disease
Internal dose
Health Effect
Biologically effective dose
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Environmental exposure pathways II
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. . . . PEOPLE . . .
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ENVIRONMENTAL EXPOSURES INFLUENCED BY HUMAN
BEHAVIOR AND THE SOCIAL ENVIRONMENT?. . . .
and vice-versa? . . . .